EP3121396A1 - System for varying cylinder valve timing in an internal combustion engine - Google Patents
System for varying cylinder valve timing in an internal combustion engine Download PDFInfo
- Publication number
- EP3121396A1 EP3121396A1 EP16275101.0A EP16275101A EP3121396A1 EP 3121396 A1 EP3121396 A1 EP 3121396A1 EP 16275101 A EP16275101 A EP 16275101A EP 3121396 A1 EP3121396 A1 EP 3121396A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- port
- valve
- actuator
- control system
- valve member
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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- 238000002485 combustion reaction Methods 0.000 title claims abstract description 11
- 230000008929 regeneration Effects 0.000 claims abstract description 86
- 238000011069 regeneration method Methods 0.000 claims abstract description 86
- 239000012530 fluid Substances 0.000 claims description 105
- 238000004891 communication Methods 0.000 claims description 85
- 230000004044 response Effects 0.000 claims description 4
- 239000003921 oil Substances 0.000 description 151
- 230000009977 dual effect Effects 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 239000010705 motor oil Substances 0.000 description 5
- 238000003306 harvesting Methods 0.000 description 4
- 230000001172 regenerating effect Effects 0.000 description 4
- 230000002411 adverse Effects 0.000 description 3
- 230000002457 bidirectional effect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000002401 inhibitory effect Effects 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 230000000979 retarding effect Effects 0.000 description 2
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000001050 lubricating effect Effects 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 238000013021 overheating Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L1/00—Valve-gear or valve arrangements, e.g. lift-valve gear
- F01L1/34—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift
- F01L1/344—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear
- F01L1/3442—Valve-gear or valve arrangements, e.g. lift-valve gear characterised by the provision of means for changing the timing of the valves without changing the duration of opening and without affecting the magnitude of the valve lift changing the angular relationship between crankshaft and camshaft, e.g. using helicoidal gear using hydraulic chambers with variable volume to transmit the rotating force
- F01L2001/34423—Details relating to the hydraulic feeding circuit
- F01L2001/34426—Oil control valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/30505—Non-return valves, i.e. check valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/3056—Assemblies of multiple valves
- F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
- F15B2211/3057—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having two valves, one for each port of a double-acting output member
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/30—Directional control
- F15B2211/305—Directional control characterised by the type of valves
- F15B2211/3056—Assemblies of multiple valves
- F15B2211/30565—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve
- F15B2211/3058—Assemblies of multiple valves having multiple valves for a single output member, e.g. for creating higher valve function by use of multiple valves like two 2/2-valves replacing a 5/3-valve having additional valves for interconnecting the fluid chambers of a double-acting actuator, e.g. for regeneration mode or for floating mode
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/70—Output members, e.g. hydraulic motors or cylinders or control therefor
- F15B2211/705—Output members, e.g. hydraulic motors or cylinders or control therefor characterised by the type of output members or actuators
- F15B2211/7058—Rotary output members
Definitions
- the present invention relates to variable cylinder valve timing systems for internal combustion engines, and in particular to apparatus for hydraulically operating an actuator that varies a phase relationship between a crankshaft and a cam shaft.
- Internal combustion engines have a plurality of cylinders containing pistons that are connected to drive a crankshaft.
- Each cylinder has two or more valves that control the flow of air into the cylinder and the flow of exhaust gases therefrom.
- the valves were operated by a cam shaft which is mechanically connected to be rotated by the crankshaft. Gears, chains, or belts have been used to couple the crankshaft to the cam shaft. It is important that the valves open and close at the proper times during the combustion cycle of each cylinder. Heretofore, that valve timing relationship was fixed by the mechanical coupling between the crankshaft and the cam shaft.
- valve timing often was a compromise that produced the best overall operation at all engine operating speeds.
- optimum engine performance can be obtained if the valve timing varies as a function of engine speed, engine load, and other factors.
- computerized engine control it became possible to determine the optimum cylinder valve timing based on current operating conditions and in response adjust that timing accordingly.
- FIG. 1 An exemplary variable cylinder timing system is shown in Figure 1 , in which an engine computer 11 determines the optimum valve timing and applied electric current to a four-way electrohydraulic valve 10 that controls the flow of pressurized oil from a pump 13 to a cam phase actuator 12.
- the pump 13 typically is the conventional one used to send lubricating oil through the engine.
- the cam phase actuator 12 couples the cam shaft 14 to a pulley 16 that is driven by a timing belt which engages another pulley on the crankshaft of the engine.
- a pulley a chain sprocket, a gear, or other device may be employed to mechanically couple the cam shaft 14 to the crankshaft.
- a sensor 15 provides an electrical feedback signal to the engine computer 11 indicating the angular phase of the cam shaft 14.
- the cam phase actuator 12 has a rotor 20 secured to the cam shaft 14.
- the cam phase actuator 12 has four vanes 22 projecting outward into four chambers 25 in the timing belt pulley 16, thereby defining first and second cavities 26 and 28 in each chamber on opposite sides to the respective vane.
- a first port 18 in the actuator manifold 15 is connected by a first passageway 30 to the first cavities 26 and a second passageway 33 couples a second port 19 to the second cavities 28.
- the angular phase relationship between the rotating pulley 16 and the cam shaft 14 can be varied to either advance or retard the cylinder valve timing.
- the electrohydraulic valve 10 When the electrohydraulic valve 10 is energized into the center, or neutral, position, fluid from the pump 10 is fed equally into both the first and second cavities 26 and 28 in each timing pulley chamber 25. The equal pressure on both sides of the rotor vanes 22 maintains the present position of those vanes in the pulley chambers 25.
- the electrohydraulic valve 10 operates in the center position the majority of the time that the engine is running. Note that electric current has to be applied to the electrohydraulic valve 10 to maintain this centered position.
- pressurized oil from the pump 13 is applied to the first port 18 and other oil is exhausted from the second port 19 to a reservoir 17 (e.g., the oil pan). That pressurized oil is conveyed into the first cavities 26, thereby forcing the rotor 20 clockwise with respect to the timing belt pulley 16 and advancing the valve timing.
- pressurized oil from the pump is applied to the second port 19, while oil is exhausted from the first port 18 to the reservoir 17. Now pressurized oil is being sent into the second cavities 28, thereby forcing the rotor 20 counterclockwise with respect to the timing belt pulley 16, which retards the valve timing.
- references herein to directional relationships and movement such as left and right, or clockwise and counterclockwise, refer to the relationship and movement of the components in the orientation illustrated in the drawings, which may not be the same for the components as attached to machinery.
- the term "directly connected” as used herein means that the associated hydraulic components are connected together by a conduit without any intervening element, such as a valve, an orifice or other device, which restricts or controls the flow of fluid beyond the inherent restriction of any conduit.
- components that are said to be “in fluid communication” are operatively connected in a manner wherein fluid flows between those components.
- cam phase actuator 12 requires significant oil pressure and flow from the engine oil pump to overcome the torque profile of the cam shaft and adjust the cam timing.
- electrohydraulic valve 10 consumes electric current while placed into the center position the majority of the engine operating time. It is desirable to reduce hydraulic and electrical energy consumption and thereby improve efficiency of the cam phasing system.
- some embodiments of the invention provide a control system for varying cylinder valve timing of an internal combustion engine.
- the internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft.
- the control system includes a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port.
- the control system further includes a first control valve having a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator.
- the first control valve having a first position in which fluid communication is provided between the first port and the first workport, and having a second position in which fluid communication is provided between the second port and the first workport.
- the control system further includes a second control valve having a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port.
- the second control valve having one position in which fluid communication is provided between the third port and the second workport, and having another position in which fluid communication is provided between the fourth port and the second workport.
- the control system further includes a dynamic regeneration valve configured to enable the cam phase actuator to switch between operating in an oil pressure actuated mode and a cam toque actuated mode when adjusting the rotational phase of the camshaft relative to the crankshaft.
- some embodiments of the invention provide a control system for varying cylinder valve timing of an internal combustion engine.
- the internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft.
- the control system includes a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port.
- the control system further includes a first control valve having a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator.
- the first control valve having a first position in which fluid communication is provided between the first port and the first workport, and having a second position in which fluid communication is provided between the second port and the first workport.
- the control system further includes a second control valve having a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port.
- the second control valve having one position in which fluid communication is provided between the third port and the second workport, and having another position in which fluid communication is provided between the fourth port and the second workport.
- the control system further includes a dynamic regeneration valve configured to switch operation of the cam phase actuator between an oil pressure actuated mode and a cam torque actuated mode based on a pressure at an outlet of the pump.
- a first cam phase control system 40 utilizes oil provided by a conventional oil pump 42 that furnishes oil from a reservoir 44 for lubricating the engine.
- the outlet of the oil pump 42 is connected to first and second control valves 46 and 48.
- Each of the control valves 46 and 48 is an electrohydraulic, on/off or proportional, three-way valve that is operated by a signal from an engine computer 45.
- the engine computer 45 applies a pulse width modulated (PWM) signal to operate an on/off, three-way valve to achieve proportional variation of fluid flow through the valve.
- PWM pulse width modulated
- Each exemplary control valve 46 or 48 includes an integrated check valve 50 or 52, respectively.
- the first control valve 46 has a first port 53 that receives oil from the outlet of the oil pump 42, and has a second port 55 in fluid communication with the reservoir 44 via a return line 56.
- a first path is provided between the first port 53 and a first workport 54.
- a first spring 61 biases the first control valve 46 toward the first position.
- the first check valve 50 allows oil to flow in the first path only from the first port 53 to the first workport 54 and prevents oil from flowing in the opposite direction.
- a first solenoid actuator 63 is activated by an electric current from the engine computer 45, the first control valve 46 moves into a second position. In that second position, the first control valve 46 provides a bidirectional second path between the first workport 54 and the second port 55 and thus to the reservoir 44.
- the second control valve 48 has a third port 57 connected to the outlet of the oil pump 42, and has a fourth port 59 that is connected to the reservoir 44 via the return line 56.
- a third path is provided between the third port 57 and a second workport 58.
- a second spring 62 biases the second control valve 46 toward that one position. Fluid flow through the third path is restricted by the second check valve 52 to only a direction from the third port 57 to a second workport 58.
- Another position of the second control valve 48 provides a bidirectional fourth fluid path between the second workport 58 and the fourth port 59.
- An electric current from the engine controller activates a second solenoid actuator 64 to move the second control valve 48 into that other position.
- the first cam phase control system 40 includes a cam phase actuator 68 for varying the rotational relationship between the crankshaft and the cam shaft of the engine.
- the cam phase actuator 68 is a conventional, hydraulically operated device used for that purpose and may be similar to the actuator shown in Figures 1 and 2 .
- the cam phase actuator 68 has a first actuator port 66 that is directly connected to the first workport 54 of the first control valve 46, and has a second actuator port 70 that is directly connected to the second workport 58 of the second control valve 48.
- the present cam phase control system consumes less energy than the previous system that employed a four-way control valve, as in Figure 1 .
- Prior cam phase actuators also required a locking mechanism to hold the actuator in a fixed position when the cam phasing was not being adjusted.
- the first cam phase control system 40 does not require a locking mechanism, because when the cam phase actuator 68 is not being adjusted, the check valves 50 and 52 hold the oil within the cam phase actuator 68 and prevent the change in the cam phase relationship.
- the first cam phase control system 40 provides bidirectional energy harvesting of cam torque for use in adjusting the cam phasing. This further conserves energy and enables adjustment of the cam phasing at near zero oil supply pressure.
- the first control valve 46 remains de-energized while the second control valve 48 is operated into the position in which the second workport 58 is connected to the fourth port 59 to which the reservoir return line 56 connects.
- This enables pressurized fluid from the oil pump 42 to be fed into the first actuator port 66 and other fluid to be drained from the second actuator port 70 back to the reservoir 44.
- This causes the cam phase actuator 68 to change the phase relationship between crank shaft and the cam shaft and thereby advance the cylinder valve timing.
- engine computer de-energizes the second solenoid actuator 64 which returns the second control valve 48 to the illustrated position in which the adjusted cam phase is maintained.
- the engine cylinder valves exert torque onto the cam shaft that tends to alter the position relationship of the components in the cam phase actuator and thus the phase relationship between the crankshaft and the cam shaft.
- the net torque aids adjusting the cam phase in the desired direction thereby supplementing the adjustment force from the pump pressure.
- the net torque opposes the desired cam phase adjustment.
- the cam shaft torque tends to cause the cam phase actuator 68 to push oil backwards through the first control valve 46 to the oil pump 42. For example such backward flow may occur at low engine speeds, when the pump is producing a low output pressure.
- the first and second check valves 50 and 52 prevent that reverse flow, thereby enabling the system to operate effectively over a wider range of engine conditions, such as low pump output pressure, oil temperatures, and engine speeds.
- the present system takes advantage of the net cam shaft torque in rotational direction that aids adjustment of the cam phasing, while inhibiting the effect of adverse cam torque that opposes the desired cam phase adjustment.
- the present control system harvests the positive cam torque energy, while preventing the adverse effects of the negative cam torque energy.
- This harvesting of cam torque for use in adjusting the cam phasing conserves energy and enables adjustment of the cam phasing at near zero oil supply pressure.
- the first control valve 46 is electrically operated so that the first workport 54 is connected to the second port 55, thereby allowing fluid to be exhausted from the cam phase actuator to the reservoir 44.
- the second control valve 48 is de-energized and thus is biased by the spring 62 into the illustrated position.
- oil from the pump 42 is applied to the second workport 58 and the second actuator port 70 of the cam phase actuator 68.
- the second check valve 52 enables harvesting of the positive cam torque energy while inhibiting the adverse effects of the negative cam torque energy.
- check valves 50 and 52 instead of being integrated into the first and second control valves 46 and 48, could be located outside those valves in the conduits that are connected to the respective first and third ports 53 and 57.
- a second cam phase actuator 72 is provided for the other cam shaft and has actuator ports 74 and 75 connected to the 54 and 58, respectively, of the first and second control valves 46 and 48.
- the first and second cam phase actuators 68 and 72 are similar to the actuator 12 in Figures 1 and 2 , except that the first passageway 30 communicates with the first actuator port and the second passageway 33 communicates with the second actuator port, during only a portion of each rotation of the cam shaft 14.
- the first actuator port 66 in the actuator manifold 76 opens into an arcuate recess 77 that extends 90 degrees around the circumference of the bore in which the rotor 20 rotates.
- a radial aperture 78 in the rotor 20 extends from the outer circumferential surface to first passageway 30 that continues to the first cavities 26.
- the manifold's arcuate recess 77 and rotor's radial aperture 78 are arranged so that they are in fluid communication when the cam shaft is rotationally positioned between 0 degrees and 90 degrees.
- the second actuator port 70 of the first cam phase actuator 68 is similarly arranged to be in fluid communication with the second passageway 33, for the second cavities 28, when the cam shaft is between 0 and 90 degrees.
- One skilled in the art will appreciate that other angles and angle ranges may be used in controlling two or more cam phase actuators.
- the second cam phase actuator 72 has a similar design, except that the arcuate recesses 77 are located so that the first and second actuator ports 74 and 75 communicate with the first and second passageways 30 and 33, respectively, when the cam shaft is between 180 degrees and 270 degrees during each rotation. Because of that angular offset of the arcuate recesses, the first and second cavities 26 and 28 of the first cam phase actuator 68 are actively connected to the control valve workports 54 and 58 at different times during each rotation of the cam shafts than when the first and second cavities 26 and 28 of the second cam phase actuator 72 are actively connected to the control valve workports. This enables the cam shaft phasing provided by the two cam phase actuators 68 and 72 to be controlled separately.
- control valves 46 and 48 are operated by the engine computer to vary the phasing of the first cam phase actuator 68; and when the dual cam shafts are between 180 degrees and 270 degrees, the control valves are operated to vary the phasing of the second cam phase actuator 72.
- a second embodiment of the present control system provides regeneration using fluid being exhausted from the cam phase actuator.
- This regenerative circuit reduces the amount of oil flow required from the pump to only that which is needed to replace fluid that leaks from the cam phase actuator and the control valves into the engine.
- a conventional oil pump 82 feeds fluid from a reservoir 84 (e.g. the engine oil pan) to a pair of electrohydraulic, three-way control valves 86 and 88.
- the outlet of the oil pump 82 is connected to a first port 92 of the first control valve 86, that also has a second port 94 and a first workport 93.
- the first workport 93 is directly connected to a first actuator port 106 of a cam phase actuator 104 and the second port 94 is coupled to a second actuator port 108 by a first regeneration line 100.
- a third check valve 95 allows oil to flow through the first regeneration line 100 only in a direction from second port 94 to the second actuator port 108.
- the outlet of the oil pump 82 also is connected to a third port 96 of the second control valve 88, that has a fourth port 98 and a second workport 97 as well.
- the second workport 97 is directly connected to the second actuator port 108 of the cam phase actuator 104, and the fourth port 98 is coupled to the first actuator port 106 by a second regeneration line 102.
- a fourth check valve 99 permits oil to flow through the second regeneration line 102 only in a direction from fourth port 98 to the first actuator port 106.
- cam phase actuators are provided for each cam shaft and such actuators are coupled to the workports 93 and 97 of the two control valves 86 and 88 in the same manner as for the cam phase actuator 104.
- the second cam phase control system 80 functions the same as the first cam phase control system 40 when the both its control valves 46 and 48 are de-energized.
- the first control valve 86 remains de-energized and the second control valve 88 is electrically operated into the position that connects the second workport 97 to the fourth port 98.
- pressurized oil from the oil pump 82 is applied through the first control valve 86 to the first actuator port 106 of the cam phase actuator 104.
- oil flows out of the second actuator port 108 through the second control valve 88, the fourth check valve 99, and the second regeneration line 102.
- the oil flowing through the second regeneration line 102 combines with the oil from the pump which is flowing out of the first workport 93. Therefore, the oil being exhausted from the second actuator port 108 is supplied in a regenerative manner to the first actuator port 106, thereby reducing the amount of flow required from the oil pump 82 to operate the cam phase actuator 104.
- This hydraulic regeneration reduces the amount energy consumed by the oil pump 82.
- the oil pump 82 does not have to be significantly increased in size, over that required to effectively lubricate the engine, in order for the pump also to supply the second cam phase control system 80.
- the first control valve 86 is energized to the position in which the first workport 93 is connected to the second port 94.
- the second control valve 88 is maintained de-energized to provide a path that conveys pump output oil from the third port 96 to the second workport 97.
- oil exhausting from the first actuator port 106 of the cam phase actuator 104 is fed back in a regenerative manner through the first control valve 86, the third check valve 95 and the first regeneration line 100 to the second actuator port 108. That regenerative flow combines with any additional flow required from the oil pump 82 that is conveyed through the second control valve 88, to actuate the cam phase actuator 104.
- the second embodiment in Figure 5 could be varied by providing regeneration to only one of the actuator ports 106 or 108, but not to the other actuator port.
- the first regeneration line 100 could be replaced by a line connecting the second port 94 of the first control valve 86 to the reservoir 84.
- the flow out of the second port 94 is returned to the reservoir 84, while the flow out of the fourth port 98 of the second control valve 88 still flows through the second regeneration line 102 to the first actuator port 106.
- the net torque acting on the camshaft can be used to provide cam phasing in the desired direction.
- a cam phase control system When operating in a torque actuated mode, a cam phase control system only requires enough oil flow to make up for leakage and, therefore, does not substantially effect the pressure in the main oil galley of an engine.
- the main oil galley of an engine typically located in the engine block, provides a passage way for oil to travel to many of the engine's main components, such as crank shaft bearings, cam gear(s)/bearing(s), and crank rod bearings to name a few.
- drastic changes in pressure in the main oil galley of an engine can result in insufficient oil being delivered to a main component of the engine and cause overheating and/or engine failure.
- a third embodiment of a control system that provides a hybrid cam phase control system 200 that minimizes its impact on the pressure in the main oil galley of an engine by controlling when the hybrid cam phase control system 200 is operating in a cam torque actuated mode or an oil pressure actuated mode, as will be described in great detail below.
- the hybrid cam phase control system 200 can utilize a dynamic regeneration valve 202, shown in Figure 6 , which enables the hybrid cam phase control system 200 to switch between the cam torque actuated mode and the oil pressure actuated mode when adjusting the cylinder valve timing.
- the dynamic regeneration valve 202 includes a housing 204 and a valve member 206 arranged within the housing 204.
- the housing 204 defines a pressure port 208, a regeneration port 210, and a tank port 212.
- the valve member 206 illustrated in Figure 6 is a spool.
- the valve member 206 is configured to be moveable between a first valve member position ( Figure 6 ) where fluid communication between the regeneration port 210 and the tank port 212 is inhibited and a second valve member position where fluid communication is provided between the regeneration port 210 and the tank port 212.
- a regeneration spring 214 biases the valve member 206 towards the first valve member position.
- a force acting on a bottom surface 216 of the valve member 206 will eventually overcome the force of the regeneration spring 214 and the valve member 206 will move from the first valve member position to the second valve member position.
- a conventional oil pump 220 feeds fluid from a reservoir 222 (e.g., the engine oil pan) to a first control valve 224, a second control valve 226, and the dynamic regeneration valve 202.
- the first control valve 224 and the second control valve 226 are each electrohydraulic, three-way control valves operated by a signal from an engine computer 227.
- a first port 228 of the first control valve 224 is in fluid communication with the outlet of the oil pump 220, and a first check valve 230 is arranged between the outlet of the oil pump 220 and the first port 228.
- the first check valve 230 only allows oil to flow from the outlet of the oil pump 220 to the first port 228 and prevents oil from flowing in the opposite direction.
- the first check valve 230 can be arranged within the first control valve 224, similar to check valves 50 and 90 described above.
- the first control valve 224 When the first control valve 224 is in a first position illustrated in Figure 7 , the first control valve 224 provides fluid communication between the first port 228 and a first workport 232.
- the first control valve 224 is biased towards the first position by a first spring 234.
- a first solenoid actuator 236 When a first solenoid actuator 236 is energized by an electric current from the engine computer 227, the first solenoid actuator 236 overcomes the force of the first spring 234 and the first control valve 224 moves into a second position.
- the first control valve 224 In the second position, the first control valve 224 provides fluid communication between the first workport 232 and a second port 238.
- the second port 238 is in fluid communication with the regeneration port 210 of the dynamic regeneration valve 202.
- a third port 240 of the second control valve 226 is in fluid communication with the outlet of the oil pump 220, and a second check valve 242 is arranged between the outlet of the oil pump 220 and the third port 240.
- the second check valve 242 only allows oil to flow from the outlet of the oil pump 220 to the third port 240 and prevents oil from flowing in the opposite direction.
- the second check valve 242 can be arranged within the second control valve 226, similar to check valves 52 and 91 described above.
- the second control valve 226 When the second control valve 226 is in one position, the second control valve 226 provides fluid communication between the third port 240 and a second workport 244. The second control valve 226 is biased towards that one position by a second spring 246.
- a second solenoid actuator 248 When a second solenoid actuator 248 is activated by an electric current from the engine computer 227, the second solenoid actuator 248 overcomes the force of the second spring 246 and the second control valve 226 moves into another position illustrated in Figure 7 . In that other position, the second control valve 226 provides fluid communication between the second workport 244 and a fourth port 250.
- the fourth port 250 is in fluid communication with the regeneration port 210 of the dynamic regeneration valve 202.
- a sensing line 252 provides fluid communication between the pressure port 208 of the dynamic regeneration valve 202 and the outlet of the oil pump 220.
- the pressure at the outlet of the oil pump 220 does not provide a force on the bottom surface 216 of the valve member 206 sufficient to overcome the force of the regeneration spring 214, the valve member 206 is forced into the first valve member position and the dynamic regeneration valve 202 inhibits fluid communication between the regeneration port 210 and the tank port 212 and thus to the reservoir 222.
- the dynamic regeneration valve 202 provides fluid communication between the regeneration port 210 and the tank port 212 and thus to the reservoir 222.
- the hybrid cam phase control system 200 includes a cam phase actuator 254 for varying the rotational relationship between the crankshaft and the cam shaft of the engine.
- the cam phase actuator 254 can be a conventional, hydraulically actuated device similar to the actuator shown in Figures 1 and 2 . Alternatively or additionally, the cam phase actuator 254 can be configured to operate similar to the cam phase actuator 68 shown in Figure 4 and described above.
- the cam phase actuator 254 includes a first actuator port 256 in fluid communication with the first workport 232 and a second actuator port 258 in fluid communication with the second workport 244.
- the hybrid cam phase control system 200 also includes a third check valve 260, a fourth check valve 262, and a re-circulation line 264.
- the third check valve 260 inhibits fluid communication between the first workport 232 and the re-circulation line 264, and also inhibits fluid communication between the first actuator port 256 and the re-circulation line 264.
- the fourth check valve 262 inhibits fluid communication between the second workport 244 and the re-circulation line 264, and also inhibits fluid communication between the second actuator port 258 and the re-circulation line 264.
- the re-circulation line 264 provides fluid communication between the second port 238 and the second actuator port 258, and provides fluid communication between the fourth port 250 and the first actuator port 256.
- the hybrid cam phase control system 200 can adjust the cam phase actuator 254 using either the cam torque actuated mode or the oil pressure actuated mode. Whether the hybrid cam phase control system 200 is operating in the cam torque actuated mode or the oil pressure actuated mode, operation of the first control valve 224 and the second control valve 226 will be the same for the two modes when adjusting the cam phase actuator 254 to advance or retard the cylinder valve timing.
- the first solenoid actuator 236 is de-energized such that the first control valve 224 provides fluid communication between the first port 228 and the first workport 232
- the second solenoid actuator 248 is energized such that the second control valve 226 provides fluid communication between the second workport 244 and the fourth port 250.
- the first solenoid actuator 236 is energized such that the first control valve 224 provides fluid communication between the first workport 232 and the second port 238, and the second solenoid actuator 248 is de-energized such that the second control valve 226 provides fluid communication between the third port 240 and the second workport 244. This enables oil from the oil pump 220 to be fed into the second actuator port 258 and other oil to be drained from the first actuator port 256 back to the reservoir 222.
- the valve member 206 In the oil pressure actuated mode, the valve member 206 is forced into the second valve member position and oil flowing from either the first workport 238 or the second workport 250 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow though the dynamic regeneration valve 202 to the reservoir 222.
- the cam phase actuator 254 is adjusted to advance the cylinder valve timing
- pressurized oil is fed from the pump 220 through the first control valve 224 to the first actuator port 256.
- the oil exhausted from the second actuator port 258 is fed through the second control valve 226 and the dynamic regeneration valve 202 to the reservoir 222, as shown in bold lines in Figure 7 .
- the hybrid cam phase control system 200 When the pressure at the outlet of the oil pump 220, sensed by the sensing line 252, does not provide a force on the bottom surface 216 of the valve member 206 sufficient to overcome the force of the regeneration spring 214, the hybrid cam phase control system 200 will be operating in the cam torque actuated mode and the net force acting on the camshaft will be used to adjust the cam phase actuator 254. In the cam torque actuated mode, the valve member 206 is biased into the first valve member position and oil is re-circulated through the hybrid cam phase control system 200.
- oil from the oil pump 220 can be fed into the first actuator port 256 and oil exhausted from the second actuator port 258 is fed through the second control valve 226, the re-circulation line 264, and the third check valve 260, as shown in bold lines in Figure 8 .
- the oil flowing through the re-circulation line 264 and the third check valve 260 is fed back to the first actuator port 256.
- the oil exhausted from the second actuator port 258 is re-circulated to the first actuator port 256 and the oil pump 220 only needs to supply enough oil to the first port 228 to make up for leakage. This minimizes the effect the hybrid cam phase control system 200 has on the pressure in the reservoir 222 and enables the adjustment of the cam phase actuator 254 at low oil pump pressures.
- a second cam phase actuator 266 is provided for the other cam shaft as shown in Figure 9 .
- the second cam phase actuator 266 includes one actuator port 268 in fluid communication with the first workport 232 and another actuator port 270 in fluid communication with the second workport 244.
- the cam phase actuators 254 and 266 can be designed similar to the cam phase actuators 68 and 72, described above.
- the cam phase actuator 254 can be designed such that the first and second actuator ports 256 and 258 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 0 degrees and 90 degrees.
- the second cam phase actuator can be designed such that the actuator ports 268 and 270 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 180 degrees and 270 degrees.
- the actuator ports 268 and 270 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 180 degrees and 270 degrees.
- angles and angle ranges may be used in controlling two or more cam phase actuators.
- a fourth embodiment of a control system that provides a hybrid cam phase control system 300 that minimizes its impact on the pressure in the main oil galley of an engine by controlling when the hybrid cam phase control system 300 is operating in a cam torque actuated mode or an oil pressure actuated mode, as will be described in great detail below.
- the hybrid cam phase control system 300 can utilize a dynamic regeneration valve 302, shown in Figure 10 , which enables the hybrid cam phase control system 300 to switch between the cam torque actuated mode and the oil pressure actuated mode when adjusting the cylinder valve timing.
- the dynamic regeneration valve 302 includes a housing 304 and a valve member 306 arranged within the housing 304.
- the housing 304 defines a pressure port 308, a regeneration port 310, and a tank port 312.
- the valve member 306 illustrated in Figure 11 is a poppet.
- the valve member 306 is configured to be moveable between a first valve member position ( Figure 11 ) where fluid communication is inhibited between the regeneration port 310 and the tank port 312 and a second valve member position where fluid communication is provided between the regeneration port 310 and the tank port 312.
- a regeneration spring 314 biases the valve member 306 towards the first valve member position.
- the valve member 306 includes a lower surface 316 in fluid communication with the pressure port 308 and central portion 318 in fluid communication with the regeneration port 310.
- the central portion 318 defines a differential area 319.
- a conventional oil pump 320 feeds fluid from a reservoir 322 (e.g., the engine oil pan) to a first control valve 324, a second control valve 326, and the dynamic regeneration valve 302.
- the first control valve 324 and the second control valve 326 are each electrohydraulic, three-way control valves operated by a signal from an engine computer 327.
- a first port 328 of the first control valve 324 is in fluid communication with the outlet of the oil pump 320, and a first check valve 330 is arranged between the outlet of the oil pump 320 and the first port 328.
- the first check valve 330 only allows oil to flow from the outlet of the oil pump 320 to the first port 328 and prevents oil from flowing in the opposite direction.
- the first check valve 330 can be arranged within the first control valve 324, similar to check valves 50 and 90 described above.
- the first control valve 324 When the first control valve 324 is in a first position illustrated in Figure 11 , the first control valve 324 provides fluid communication between the first port 328 and a first workport 332.
- the first control valve 324 is biased towards the first position by a first spring 334.
- a first solenoid actuator 336 When a first solenoid actuator 336 is energized by an electric current from the engine computer 327, the first solenoid actuator 336 overcomes the force of the first spring 334 and the first control valve 324 moves into a second position. In the second position, the first control valve 324 provides fluid communication between the first workport 332 and a second port 338.
- the second port 338 is in fluid communication with the regeneration port 310 of the dynamic regeneration valve 302.
- a third port 340 of the second control valve 326 is in fluid communication with the outlet of the oil pump 320, and a second check valve 342 is arranged between the outlet of the oil pump 320 and the third port 340.
- the second check valve 342 only allows oil to flow from the outlet of the oil pump 320 to the third port 340 and prevents oil from flowing in the opposite direction.
- the second check valve 342 can be arranged within the second control valve 326, similar to check valves 52 and 91 described above.
- the second control valve 326 When the second control valve 326 is in one position, the second control valve 326 provides fluid communication between the third port 340 and a second workport 344. The second control valve 326 is biased towards that one position by a second spring 346. When a second solenoid actuator 348 is activated by an electric current from the engine computer 327, the second solenoid actuator 348 overcomes the force of the second spring 346 and the second control valve 326 moves into another position illustrated in Figure 11 . In that other position, the second control valve 326 provides fluid communication between the second workport 344 and a fourth port 350. The fourth port 350 is in fluid communication with the regeneration port 310 of the dynamic regeneration valve 302.
- a sensing line 352 provides fluid communication between the pressure port 308 of the dynamic regeneration valve 302 and the outlet of the oil pump 320.
- the valve member 306 When the pressure at the outlet of the oil pump 320 does not provide a force on the bottom surface 316 of the valve member 306 sufficient to overcome the force of the regeneration spring 314, the valve member 306 is forced into the first valve member position and the dynamic regeneration valve 302 inhibits fluid communication between the regeneration port 310 and the tank port 312 and thus to the reservoir 322.
- the pressure at the outlet of the oil pump 320 reaches a sufficient level, the force acting on the bottom surface 316 of the valve member 306 overcomes the force of the regeneration spring 314 and the valve member 306 moves to the second valve member position illustrated in Figure 11 .
- the dynamic regeneration valve 302 In the second valve member position, the dynamic regeneration valve 302 provides fluid communication between the regeneration port 310 and the tank port 312 and thus to the reservoir 322.
- the hybrid cam phase control system 300 includes a cam phase actuator 354 for varying the rotational relationship between the crankshaft and the cam shaft of the engine.
- the cam phase actuator 354 can be a conventional, hydraulically actuated device similar to the actuator shown in Figures 1 and 2 . Alternatively or additionally, the cam phase actuator 354 can be configured to operate similar to the cam phase actuator 68 shown in Figure 4 and described above.
- the cam phase actuator 354 includes a first actuator port 356 in fluid communication with the first workport 332 and a second actuator port 358 in fluid communication with the second workport 344.
- the hybrid cam phase control system 300 also includes a third check valve 360, a fourth check valve 362, and a re-circulation line 364.
- the third check valve 360 inhibits fluid communication between the first workport 332 and the re-circulation line 364, and also inhibits fluid communication between the first actuator port 356 and the re-circulation line 364.
- the fourth check valve 362 inhibits fluid communication between the second workport 344 and the re-circulation line 364, and also inhibits fluid communication between the second actuator port 358 and the re-circulation line 364.
- the re-circulation line 364 provides fluid communication between the second port 338 and the second actuator port 358, and also provides fluid communication between the fourth port 350 and the first actuator port 356.
- the hybrid cam phase control system 300 can adjust the cam phase actuator 354 using either the cam torque actuated mode or the oil pressure actuated mode. Whether the hybrid cam phase control system 300 is operating in the cam torque actuated mode or the oil pressure actuated mode, operation of the first control valve 324 and the second control valve 326 will be the same for the two modes when adjusting the cam phase actuator 354 to advance or retard the cylinder valve timing.
- the first solenoid actuator 336 is de-energized such that the first control valve 324 provides fluid communication between the first port 328 and the first workport 332, and the second solenoid actuator 348 is energized such that the second control valve 326 provides fluid communication between the second workport 344 and the fourth port 350.
- This enables oil from the oil pump 320 to be fed into the first actuator port 356 and other oil to be drained from the second actuator port 358 back to the reservoir 322.
- the first solenoid actuator 336 is energized such that the first control valve 324 provides fluid communication between the first workport 332 and the second port 338, and the second solenoid actuator 348 is de-energized such that the second control valve 326 provides fluid communication between the third port 340 and the second workport 344.
- This enables oil from the oil pump 320 to be fed into the second actuator port 358 and other oil to be drained from the first actuator port 356 back to the reservoir 322.
- valve member 306 In the oil pressure actuated mode, the valve member 306 is forced into the second valve member position and oil flowing from either the first workport 338 or the second workport 350 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow though the dynamic regeneration valve 302 to the reservoir 322.
- the cam phase actuator 354 is adjusted to advance the cylinder valve timing
- pressurized oil is fed from the pump 320 through the first control valve 324 to the first actuator port 356.
- the oil exhausted from the second actuator port 358 is fed through the second control valve 326 and the dynamic regeneration valve 302 to the reservoir 322, as shown in bold lines in Figure 11 .
- the valve member 306 is in the second valve member position while the hybrid cam phase control system 300 is operating in the oil pressure assisted mode.
- the differential area 319 defined by the central portion 318 of the valve member 306 enables the valve member 306 to increase or decrease a flow area between the regeneration port 310 and the tank port 312 in response to the pressure at the regeneration port 310.
- the illustrated differential area 319 enables the valve member 306 to increase the flow area between the regeneration port 310 and the tank port 312 as the valve member 306 lifts in response to the pressure spike.
- This functionality of the valve member 306 is illustrated by a regeneration sensing line 365 in Figures 11-14 .
- Figure 12 illustrates, in bold lines, the above described example where the hybrid cam phase control system 300 is operating in the oil pressure actuated mode and the pressure at the regeneration port 310 further forces the valve member 306 to lift and increase the flow area between the regeneration port 310 and the tank port 312.
- the differential area 319 may be designed to either provide additional flow area between the regeneration port 310 and the tank port 312 during a spike in pressure at the regeneration port 310 or provide additional closing of the flow area between the regeneration port 310 and the tank port 312 during a spike in pressure at the regeneration port 310, compared to the differential area 319 illustrated in Figure 10 .
- the differential area 319 can be designed to reduce the resistance of the hydraulic circuit illustrated in Figures 11-14 and provide faster shifting rates by providing additional flow area.
- the differential area 319 can be designed to ensure that the hybrid cam phase control system 300 will default to the oil pressure actuated mode if consistent pressure spikes at the regeneration port 310 stop occurring.
- the hybrid cam phase control system 300 When the pressure at the outlet of the oil pump 320, sensed by the sensing line 352, does not provide a force on the bottom surface 316 of the valve member 306 sufficient to overcome the force of the regeneration spring 314, the hybrid cam phase control system 300 will be operating in the cam torque actuated mode and the net force acting on the camshaft will be used to adjust the cam phase actuator 354. In the cam torque actuated mode, the valve member 306 is biased into the first valve member position and oil is re-circulated through the hybrid cam phase control system 300.
- oil from the oil pump 320 can be fed into the first actuator port 356 and oil exhausted from the second actuator port 358 is fed through the second control valve 326, the re-circulation line 364, and the third check valve 360, as shown in bold lines in Figure 13 .
- the oil flowing through the re-circulation line 364 and the third check valve 360 is fed back to the first actuator port 356.
- the oil exhausted from the second actuator port 358 is re-circulated to the first actuator port 356 and the oil pump 320 only needs to supply enough oil to the first port 328 to make up for leakage. This minimizes the effect the hybrid cam phase control system 300 has on the pressure in the reservoir 222 and enables the adjustment of the cam phase actuator 354 at low oil pump pressures.
- a second cam phase actuator 366 is provided for the other cam shaft as shown in Figure 14 .
- the second cam phase actuator 366 includes one actuator port 368 in fluid communication with the first workport 332 and another actuator port 370 in fluid communication with the second workport 344.
- the cam phase actuators 354 and 366 can be designed similar to the cam phase actuators 68 and 72, described above.
- the cam phase actuator 354 can be designed such that the first and second actuator ports 356 and 358 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 0 degrees and 90 degrees.
- the second cam phase actuator can be designed such that the actuator ports 368 and 370 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 180 degrees and 270 degrees.
- the actuator ports 368 and 370 can be in communication with the first and second passageways 30 and 33 when the cam shaft is rotationally positioned between 180 degrees and 270 degrees.
- angles and angle ranges may be used in controlling two or more cam phase actuators.
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Abstract
Description
- The present invention relates to variable cylinder valve timing systems for internal combustion engines, and in particular to apparatus for hydraulically operating an actuator that varies a phase relationship between a crankshaft and a cam shaft.
- Internal combustion engines have a plurality of cylinders containing pistons that are connected to drive a crankshaft. Each cylinder has two or more valves that control the flow of air into the cylinder and the flow of exhaust gases therefrom. The valves were operated by a cam shaft which is mechanically connected to be rotated by the crankshaft. Gears, chains, or belts have been used to couple the crankshaft to the cam shaft. It is important that the valves open and close at the proper times during the combustion cycle of each cylinder. Heretofore, that valve timing relationship was fixed by the mechanical coupling between the crankshaft and the cam shaft.
- The fixed setting of the valve timing often was a compromise that produced the best overall operation at all engine operating speeds. However, it has been recognized that optimum engine performance can be obtained if the valve timing varies as a function of engine speed, engine load, and other factors. With the advent of computerized engine control, it became possible to determine the optimum cylinder valve timing based on current operating conditions and in response adjust that timing accordingly.
- An exemplary variable cylinder timing system is shown in
Figure 1 , in which anengine computer 11 determines the optimum valve timing and applied electric current to a four-wayelectrohydraulic valve 10 that controls the flow of pressurized oil from apump 13 to a cam phase actuator 12. Thepump 13 typically is the conventional one used to send lubricating oil through the engine. The cam phase actuator 12 couples thecam shaft 14 to apulley 16 that is driven by a timing belt which engages another pulley on the crankshaft of the engine. Instead of a pulley, a chain sprocket, a gear, or other device may be employed to mechanically couple thecam shaft 14 to the crankshaft. Asensor 15 provides an electrical feedback signal to theengine computer 11 indicating the angular phase of thecam shaft 14. - With additional reference to
Figure 2 , the cam phase actuator 12 has arotor 20 secured to thecam shaft 14. The cam phase actuator 12 has fourvanes 22 projecting outward into fourchambers 25 in thetiming belt pulley 16, thereby defining first andsecond cavities first port 18 in theactuator manifold 15 is connected by afirst passageway 30 to thefirst cavities 26 and asecond passageway 33 couples asecond port 19 to thesecond cavities 28. - By selectively controlling the application of engine oil to the first and
second ports pulley 16 and thecam shaft 14 can be varied to either advance or retard the cylinder valve timing. When theelectrohydraulic valve 10 is energized into the center, or neutral, position, fluid from thepump 10 is fed equally into both the first andsecond cavities timing pulley chamber 25. The equal pressure on both sides of therotor vanes 22 maintains the present position of those vanes in thepulley chambers 25. Theelectrohydraulic valve 10 operates in the center position the majority of the time that the engine is running. Note that electric current has to be applied to theelectrohydraulic valve 10 to maintain this centered position. - In another position of the
electrohydraulic valve 10, pressurized oil from thepump 13 is applied to thefirst port 18 and other oil is exhausted from thesecond port 19 to a reservoir 17 (e.g., the oil pan). That pressurized oil is conveyed into thefirst cavities 26, thereby forcing therotor 20 clockwise with respect to thetiming belt pulley 16 and advancing the valve timing. In yet another position ofelectrohydraulic valve 10, pressurized oil from the pump is applied to thesecond port 19, while oil is exhausted from thefirst port 18 to the reservoir 17. Now pressurized oil is being sent into thesecond cavities 28, thereby forcing therotor 20 counterclockwise with respect to thetiming belt pulley 16, which retards the valve timing. - References herein to directional relationships and movement, such as left and right, or clockwise and counterclockwise, refer to the relationship and movement of the components in the orientation illustrated in the drawings, which may not be the same for the components as attached to machinery. The term "directly connected" as used herein means that the associated hydraulic components are connected together by a conduit without any intervening element, such as a valve, an orifice or other device, which restricts or controls the flow of fluid beyond the inherent restriction of any conduit. As also used herein, components that are said to be "in fluid communication" are operatively connected in a manner wherein fluid flows between those components.
- Operation of the cam phase actuator 12 requires significant oil pressure and flow from the engine oil pump to overcome the torque profile of the cam shaft and adjust the cam timing. In addition, the
electrohydraulic valve 10 consumes electric current while placed into the center position the majority of the engine operating time. It is desirable to reduce hydraulic and electrical energy consumption and thereby improve efficiency of the cam phasing system. - In one aspect, some embodiments of the invention provide a control system for varying cylinder valve timing of an internal combustion engine is provided. The internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft. The control system includes a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port. The control system further includes a first control valve having a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator. The first control valve having a first position in which fluid communication is provided between the first port and the first workport, and having a second position in which fluid communication is provided between the second port and the first workport. The control system further includes a second control valve having a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port. The second control valve having one position in which fluid communication is provided between the third port and the second workport, and having another position in which fluid communication is provided between the fourth port and the second workport. The control system further includes a dynamic regeneration valve configured to enable the cam phase actuator to switch between operating in an oil pressure actuated mode and a cam toque actuated mode when adjusting the rotational phase of the camshaft relative to the crankshaft.
- In another aspect, some embodiments of the invention provide a control system for varying cylinder valve timing of an internal combustion engine is provided. The internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft. The control system includes a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port. The control system further includes a first control valve having a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator. The first control valve having a first position in which fluid communication is provided between the first port and the first workport, and having a second position in which fluid communication is provided between the second port and the first workport. The control system further includes a second control valve having a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port. The second control valve having one position in which fluid communication is provided between the third port and the second workport, and having another position in which fluid communication is provided between the fourth port and the second workport. The control system further includes a dynamic regeneration valve configured to switch operation of the cam phase actuator between an oil pressure actuated mode and a cam torque actuated mode based on a pressure at an outlet of the pump.
- The following drawings depict examples of variable cam adjustment systems according to the present invention with the understanding that other components and hydraulic circuits may be employed to implement the present invention.
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FIGURE 1 is a schematic diagram of a previous variable cam adjustment system the included a cam phase actuator. -
FIGURE 2 is a cross section view along line 2-2 inFigure 1 through the cam phase actuator. -
FIGURE 3 is a schematic diagram of a first embodiment of a hydraulic circuit according to the present invention. -
FIGURE 4 is a radial cross section view through a cam phase actuator in the first embodiment. -
FIGURE 5 is a schematic diagram of a second embodiment of a hydraulic circuit according to the present invention. -
FIGURE 6 is a cross-sectional view of a dynamic regeneration valve according to one embodiment of the present invention. -
FIGURE 7 is a schematic view of a third embodiment of a hydraulic circuit according to the present invention operating in an oil pressure actuated mode. -
FIGURE 8 is a schematic view of the hydraulic circuit ofFigure 7 operating in a cam torque actuated mode. -
FIGURE 9 is a schematic view of the hydraulic circuit ofFigure 7 illustrating the use of dual cam shafts. -
FIGURE 10 is a cross-sectional view of a dynamic regeneration valve according to another embodiment of the present invention. -
FIGURE 11 is a schematic view of a fourth embodiment of a hydraulic circuit according to the present invention operating in an oil pressure actuated mode. -
FIGURE 12 is a schematic view of the hydraulic circuit ofFigure 11 illustrating elevated pressure at a regeneration port. -
FIGURE 13 is a schematic view of the hydraulic circuit ofFigure 11 operating in a cam torque actuated mode. -
FIGURE 14 is a schematic view of the hydraulic circuit ofFigure 11 illustrating the use of dual cam shafts. - With initial reference to
Figure 3 , a first camphase control system 40 utilizes oil provided by aconventional oil pump 42 that furnishes oil from areservoir 44 for lubricating the engine. The outlet of theoil pump 42 is connected to first andsecond control valves control valves engine computer 45. In one implementation, theengine computer 45 applies a pulse width modulated (PWM) signal to operate an on/off, three-way valve to achieve proportional variation of fluid flow through the valve. Eachexemplary control valve integrated check valve first control valve 46 has afirst port 53 that receives oil from the outlet of theoil pump 42, and has asecond port 55 in fluid communication with thereservoir 44 via areturn line 56. When thefirst control valve 46 is in a first position as illustrated, a first path is provided between thefirst port 53 and afirst workport 54. Afirst spring 61 biases thefirst control valve 46 toward the first position. Thefirst check valve 50 allows oil to flow in the first path only from thefirst port 53 to thefirst workport 54 and prevents oil from flowing in the opposite direction. When afirst solenoid actuator 63 is activated by an electric current from theengine computer 45, thefirst control valve 46 moves into a second position. In that second position, thefirst control valve 46 provides a bidirectional second path between thefirst workport 54 and thesecond port 55 and thus to thereservoir 44. - The
second control valve 48 has athird port 57 connected to the outlet of theoil pump 42, and has afourth port 59 that is connected to thereservoir 44 via thereturn line 56. In one position of thesecond control valve 48 that is illustrated, a third path is provided between thethird port 57 and asecond workport 58. Asecond spring 62 biases thesecond control valve 46 toward that one position. Fluid flow through the third path is restricted by thesecond check valve 52 to only a direction from thethird port 57 to asecond workport 58. Another position of thesecond control valve 48 provides a bidirectional fourth fluid path between thesecond workport 58 and thefourth port 59. An electric current from the engine controller activates asecond solenoid actuator 64 to move thesecond control valve 48 into that other position. - The first cam
phase control system 40 includes acam phase actuator 68 for varying the rotational relationship between the crankshaft and the cam shaft of the engine. Thecam phase actuator 68 is a conventional, hydraulically operated device used for that purpose and may be similar to the actuator shown inFigures 1 and 2 . Thecam phase actuator 68 has afirst actuator port 66 that is directly connected to thefirst workport 54 of thefirst control valve 46, and has asecond actuator port 70 that is directly connected to thesecond workport 58 of thesecond control valve 48. - When the engine computer is not applying current to the first and
second solenoid actuators control valves springs Figure 3 . In that state, equal pressure from the outlet of theoil pump 42 is applied to bothactuator ports cam phase actuator 68. Because the first andsecond check valves second control valves cam phase actuator 68, the actuator is held in the present phase position, even at slow engine speeds when the pump outlet pressure is low and even when the engine is turned off. Holding the cam phase actuators in the last operating position ensures that appropriate valve timing will be used when the engine is restarted, in spite of an initial slow speed with minimal oil pressure being produced by thepump 42. - De-energizing the first and
second control valves cam phase actuator 68, as occurs the majority of time while the engine is operating, conserves both electrical power and hydraulic energy from the oil pump. Thus, the present cam phase control system consumes less energy than the previous system that employed a four-way control valve, as inFigure 1 . - Prior cam phase actuators also required a locking mechanism to hold the actuator in a fixed position when the cam phasing was not being adjusted. The first cam
phase control system 40 does not require a locking mechanism, because when thecam phase actuator 68 is not being adjusted, thecheck valves cam phase actuator 68 and prevent the change in the cam phase relationship. - With continuing reference to
Figure 3 , the first camphase control system 40 provides bidirectional energy harvesting of cam torque for use in adjusting the cam phasing. This further conserves energy and enables adjustment of the cam phasing at near zero oil supply pressure. - To adjust the
cam phase actuator 68 and advance the cylinder valve timing, thefirst control valve 46 remains de-energized while thesecond control valve 48 is operated into the position in which thesecond workport 58 is connected to thefourth port 59 to which thereservoir return line 56 connects. This enables pressurized fluid from theoil pump 42 to be fed into thefirst actuator port 66 and other fluid to be drained from thesecond actuator port 70 back to thereservoir 44. This causes thecam phase actuator 68 to change the phase relationship between crank shaft and the cam shaft and thereby advance the cylinder valve timing. When the cam phase reaches the desired angle, as detected by a sensor on the cam phase actuator, engine computer de-energizes thesecond solenoid actuator 64 which returns thesecond control valve 48 to the illustrated position in which the adjusted cam phase is maintained. - It should be understood that the engine cylinder valves exert torque onto the cam shaft that tends to alter the position relationship of the components in the cam phase actuator and thus the phase relationship between the crankshaft and the cam shaft. During certain segments of the revolution of the cam shaft, the net torque aids adjusting the cam phase in the desired direction thereby supplementing the adjustment force from the pump pressure. During other revolution segments, the net torque opposes the desired cam phase adjustment. Throughout those latter segments, the cam shaft torque tends to cause the
cam phase actuator 68 to push oil backwards through thefirst control valve 46 to theoil pump 42. For example such backward flow may occur at low engine speeds, when the pump is producing a low output pressure. With the first camphase control system 40, the first andsecond check valves - This harvesting of cam torque for use in adjusting the cam phasing conserves energy and enables adjustment of the cam phasing at near zero oil supply pressure.
- To adjust the
cam phase actuator 68 to retard the cylinder valve timing, thefirst control valve 46 is electrically operated so that thefirst workport 54 is connected to thesecond port 55, thereby allowing fluid to be exhausted from the cam phase actuator to thereservoir 44. At the same time, thesecond control valve 48 is de-energized and thus is biased by thespring 62 into the illustrated position. At that position, oil from thepump 42 is applied to thesecond workport 58 and thesecond actuator port 70 of thecam phase actuator 68. In this state, thesecond check valve 52 enables harvesting of the positive cam torque energy while inhibiting the adverse effects of the negative cam torque energy. - It should be understood with respect to the circuit in
Figure 3 that thecheck valves second control valves third ports - Referring still to
Figure 3 , if the engine has dual cam shafts, a secondcam phase actuator 72 is provided for the other cam shaft and hasactuator ports second control valves cam phase actuators Figures 1 and 2 , except that thefirst passageway 30 communicates with the first actuator port and thesecond passageway 33 communicates with the second actuator port, during only a portion of each rotation of thecam shaft 14. With additional reference toFigure 4 showing details of the firstcam phase actuator 68, thefirst actuator port 66 in theactuator manifold 76 opens into an arcuate recess 77 that extends 90 degrees around the circumference of the bore in which therotor 20 rotates. Aradial aperture 78 in therotor 20 extends from the outer circumferential surface tofirst passageway 30 that continues to thefirst cavities 26. The manifold's arcuate recess 77 and rotor'sradial aperture 78 are arranged so that they are in fluid communication when the cam shaft is rotationally positioned between 0 degrees and 90 degrees. Thesecond actuator port 70 of the firstcam phase actuator 68 is similarly arranged to be in fluid communication with thesecond passageway 33, for thesecond cavities 28, when the cam shaft is between 0 and 90 degrees. One skilled in the art will appreciate that other angles and angle ranges may be used in controlling two or more cam phase actuators. - The second
cam phase actuator 72 has a similar design, except that the arcuate recesses 77 are located so that the first andsecond actuator ports second passageways second cavities cam phase actuator 68 are actively connected to thecontrol valve workports second cavities cam phase actuator 72 are actively connected to the control valve workports. This enables the cam shaft phasing provided by the twocam phase actuators control valves cam phase actuator 68; and when the dual cam shafts are between 180 degrees and 270 degrees, the control valves are operated to vary the phasing of the secondcam phase actuator 72. - Referring to
Figure 5 , a second embodiment of the present control system provides regeneration using fluid being exhausted from the cam phase actuator. This regenerative circuit reduces the amount of oil flow required from the pump to only that which is needed to replace fluid that leaks from the cam phase actuator and the control valves into the engine. - In the second cam
phase control system 80, aconventional oil pump 82 feeds fluid from a reservoir 84 (e.g. the engine oil pan) to a pair of electrohydraulic, three-way control valves oil pump 82 is connected to afirst port 92 of thefirst control valve 86, that also has asecond port 94 and afirst workport 93. Thefirst workport 93 is directly connected to afirst actuator port 106 of acam phase actuator 104 and thesecond port 94 is coupled to asecond actuator port 108 by afirst regeneration line 100. Athird check valve 95 allows oil to flow through thefirst regeneration line 100 only in a direction fromsecond port 94 to thesecond actuator port 108. - The outlet of the
oil pump 82 also is connected to athird port 96 of thesecond control valve 88, that has afourth port 98 and asecond workport 97 as well. Thesecond workport 97 is directly connected to thesecond actuator port 108 of thecam phase actuator 104, and thefourth port 98 is coupled to thefirst actuator port 106 by asecond regeneration line 102. Afourth check valve 99 permits oil to flow through thesecond regeneration line 102 only in a direction fromfourth port 98 to thefirst actuator port 106. - If the engine has multiple cam shafts, separate cam phase actuators are provided for each cam shaft and such actuators are coupled to the
workports control valves cam phase actuator 104. - When the two
control valves phase control system 80 functions the same as the first camphase control system 40 when the both itscontrol valves first control valve 86 remains de-energized and thesecond control valve 88 is electrically operated into the position that connects thesecond workport 97 to thefourth port 98. In this state, pressurized oil from theoil pump 82 is applied through thefirst control valve 86 to thefirst actuator port 106 of thecam phase actuator 104. At the same time, oil flows out of thesecond actuator port 108 through thesecond control valve 88, thefourth check valve 99, and thesecond regeneration line 102. The oil flowing through thesecond regeneration line 102 combines with the oil from the pump which is flowing out of thefirst workport 93. Therefore, the oil being exhausted from thesecond actuator port 108 is supplied in a regenerative manner to thefirst actuator port 106, thereby reducing the amount of flow required from theoil pump 82 to operate thecam phase actuator 104. This hydraulic regeneration reduces the amount energy consumed by theoil pump 82. In addition, theoil pump 82 does not have to be significantly increased in size, over that required to effectively lubricate the engine, in order for the pump also to supply the second camphase control system 80. - Similarly, when it is desired to retard the cylinder valve timing, the
first control valve 86 is energized to the position in which thefirst workport 93 is connected to thesecond port 94. At the same time, thesecond control valve 88 is maintained de-energized to provide a path that conveys pump output oil from thethird port 96 to thesecond workport 97. In this mode of operation, oil exhausting from thefirst actuator port 106 of thecam phase actuator 104 is fed back in a regenerative manner through thefirst control valve 86, thethird check valve 95 and thefirst regeneration line 100 to thesecond actuator port 108. That regenerative flow combines with any additional flow required from theoil pump 82 that is conveyed through thesecond control valve 88, to actuate thecam phase actuator 104. - The second embodiment in
Figure 5 could be varied by providing regeneration to only one of theactuator ports first regeneration line 100 could be replaced by a line connecting thesecond port 94 of thefirst control valve 86 to thereservoir 84. In this variation, the flow out of thesecond port 94 is returned to thereservoir 84, while the flow out of thefourth port 98 of thesecond control valve 88 still flows through thesecond regeneration line 102 to thefirst actuator port 106. - As described above, the net torque acting on the camshaft can be used to provide cam phasing in the desired direction. When operating in a torque actuated mode, a cam phase control system only requires enough oil flow to make up for leakage and, therefore, does not substantially effect the pressure in the main oil galley of an engine. The main oil galley of an engine, typically located in the engine block, provides a passage way for oil to travel to many of the engine's main components, such as crank shaft bearings, cam gear(s)/bearing(s), and crank rod bearings to name a few. Thus, drastic changes in pressure in the main oil galley of an engine can result in insufficient oil being delivered to a main component of the engine and cause overheating and/or engine failure.
- With reference to
Figures 6 and 7 , a third embodiment of a control system that provides a hybrid camphase control system 200 that minimizes its impact on the pressure in the main oil galley of an engine by controlling when the hybrid camphase control system 200 is operating in a cam torque actuated mode or an oil pressure actuated mode, as will be described in great detail below. The hybrid camphase control system 200 can utilize adynamic regeneration valve 202, shown inFigure 6 , which enables the hybrid camphase control system 200 to switch between the cam torque actuated mode and the oil pressure actuated mode when adjusting the cylinder valve timing. Thedynamic regeneration valve 202 includes ahousing 204 and avalve member 206 arranged within thehousing 204. Thehousing 204 defines apressure port 208, aregeneration port 210, and atank port 212. Thevalve member 206 illustrated inFigure 6 is a spool. Thevalve member 206 is configured to be moveable between a first valve member position (Figure 6 ) where fluid communication between theregeneration port 210 and thetank port 212 is inhibited and a second valve member position where fluid communication is provided between theregeneration port 210 and thetank port 212. Aregeneration spring 214 biases thevalve member 206 towards the first valve member position. As the pressure at thepressure port 208 increases, a force acting on abottom surface 216 of thevalve member 206 will eventually overcome the force of theregeneration spring 214 and thevalve member 206 will move from the first valve member position to the second valve member position. - With reference to
Figure 7 , in the hybrid camphase control system 200, aconventional oil pump 220 feeds fluid from a reservoir 222 (e.g., the engine oil pan) to afirst control valve 224, asecond control valve 226, and thedynamic regeneration valve 202. Thefirst control valve 224 and thesecond control valve 226 are each electrohydraulic, three-way control valves operated by a signal from anengine computer 227. Afirst port 228 of thefirst control valve 224 is in fluid communication with the outlet of theoil pump 220, and afirst check valve 230 is arranged between the outlet of theoil pump 220 and thefirst port 228. Thefirst check valve 230 only allows oil to flow from the outlet of theoil pump 220 to thefirst port 228 and prevents oil from flowing in the opposite direction. In another embodiment, thefirst check valve 230 can be arranged within thefirst control valve 224, similar tocheck valves - When the
first control valve 224 is in a first position illustrated inFigure 7 , thefirst control valve 224 provides fluid communication between thefirst port 228 and afirst workport 232. Thefirst control valve 224 is biased towards the first position by afirst spring 234. When afirst solenoid actuator 236 is energized by an electric current from theengine computer 227, thefirst solenoid actuator 236 overcomes the force of thefirst spring 234 and thefirst control valve 224 moves into a second position. In the second position, thefirst control valve 224 provides fluid communication between thefirst workport 232 and asecond port 238. Thesecond port 238 is in fluid communication with theregeneration port 210 of thedynamic regeneration valve 202. - A
third port 240 of thesecond control valve 226 is in fluid communication with the outlet of theoil pump 220, and asecond check valve 242 is arranged between the outlet of theoil pump 220 and thethird port 240. Thesecond check valve 242 only allows oil to flow from the outlet of theoil pump 220 to thethird port 240 and prevents oil from flowing in the opposite direction. In another embodiment, thesecond check valve 242 can be arranged within thesecond control valve 226, similar tocheck valves - When the
second control valve 226 is in one position, thesecond control valve 226 provides fluid communication between thethird port 240 and asecond workport 244. Thesecond control valve 226 is biased towards that one position by asecond spring 246. When a second solenoid actuator 248 is activated by an electric current from theengine computer 227, the second solenoid actuator 248 overcomes the force of thesecond spring 246 and thesecond control valve 226 moves into another position illustrated inFigure 7 . In that other position, thesecond control valve 226 provides fluid communication between thesecond workport 244 and afourth port 250. Thefourth port 250 is in fluid communication with theregeneration port 210 of thedynamic regeneration valve 202. - With continued reference to
Figures 6 and 7 , asensing line 252 provides fluid communication between thepressure port 208 of thedynamic regeneration valve 202 and the outlet of theoil pump 220. When the pressure at the outlet of theoil pump 220 does not provide a force on thebottom surface 216 of thevalve member 206 sufficient to overcome the force of theregeneration spring 214, thevalve member 206 is forced into the first valve member position and thedynamic regeneration valve 202 inhibits fluid communication between theregeneration port 210 and thetank port 212 and thus to thereservoir 222. When the pressure at the outlet of theoil pump 220 reaches a sufficient level, the force acting on thebottom surface 216 of thevalve member 206 overcomes the force of theregeneration spring 214 and thevalve member 206 moves to the second valve member position illustrated inFigure 7 . In the second valve member position, thedynamic regeneration valve 202 provides fluid communication between theregeneration port 210 and thetank port 212 and thus to thereservoir 222. - The hybrid cam
phase control system 200 includes acam phase actuator 254 for varying the rotational relationship between the crankshaft and the cam shaft of the engine. Thecam phase actuator 254 can be a conventional, hydraulically actuated device similar to the actuator shown inFigures 1 and 2 . Alternatively or additionally, thecam phase actuator 254 can be configured to operate similar to thecam phase actuator 68 shown inFigure 4 and described above. Thecam phase actuator 254 includes afirst actuator port 256 in fluid communication with thefirst workport 232 and asecond actuator port 258 in fluid communication with thesecond workport 244. The hybrid camphase control system 200 also includes athird check valve 260, afourth check valve 262, and are-circulation line 264. Thethird check valve 260 inhibits fluid communication between thefirst workport 232 and there-circulation line 264, and also inhibits fluid communication between thefirst actuator port 256 and there-circulation line 264. Thefourth check valve 262 inhibits fluid communication between thesecond workport 244 and there-circulation line 264, and also inhibits fluid communication between thesecond actuator port 258 and there-circulation line 264. There-circulation line 264 provides fluid communication between thesecond port 238 and thesecond actuator port 258, and provides fluid communication between thefourth port 250 and thefirst actuator port 256. - Operation of the hybrid cam
phase control system 200 will be described with reference toFigures 6-8 . It should be understood that the following description of advancing and retarding the cylinder valve timing is for one rotational direction of the crankshaft and, for another rotational direction of the crankshaft, the operation of thefirst control valve 224 and thesecond control valve 226 will be opposite. Thus, the following description is one non-liming example of the operation of the hybrid camphase control system 200. - The hybrid cam
phase control system 200 can adjust thecam phase actuator 254 using either the cam torque actuated mode or the oil pressure actuated mode. Whether the hybrid camphase control system 200 is operating in the cam torque actuated mode or the oil pressure actuated mode, operation of thefirst control valve 224 and thesecond control valve 226 will be the same for the two modes when adjusting thecam phase actuator 254 to advance or retard the cylinder valve timing. - To adjust the
cam phase actuator 254 and advance the cylinder valve timing, thefirst solenoid actuator 236 is de-energized such that thefirst control valve 224 provides fluid communication between thefirst port 228 and thefirst workport 232, and the second solenoid actuator 248 is energized such that thesecond control valve 226 provides fluid communication between thesecond workport 244 and thefourth port 250. This enables oil from theoil pump 220 to be fed into thefirst actuator port 256 and other oil to be drained from thesecond actuator port 258 back to thereservoir 222. - To adjust the
cam phase actuator 254 and retard the cylinder valve timing, thefirst solenoid actuator 236 is energized such that thefirst control valve 224 provides fluid communication between thefirst workport 232 and thesecond port 238, and the second solenoid actuator 248 is de-energized such that thesecond control valve 226 provides fluid communication between thethird port 240 and thesecond workport 244. This enables oil from theoil pump 220 to be fed into thesecond actuator port 258 and other oil to be drained from thefirst actuator port 256 back to thereservoir 222. - Switching between the cam torque actuated mode and the oil pressure actuated mode is governed by the pressure at the outlet of the
oil pump 220. When the pressure at the outlet of theoil pump 220, sensed by thesensing line 252, provides a force on thebottom surface 216 of thevalve member 206 that overcomes the force of theregeneration spring 214, the hybrid camphase control system 200 will be operating in the oil pressure actuated mode and pressurized oil provided by theoil pump 220 will be adjusting thecam phase actuator 254. In the oil pressure actuated mode, thevalve member 206 is forced into the second valve member position and oil flowing from either thefirst workport 238 or the second workport 250 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow though thedynamic regeneration valve 202 to thereservoir 222. For example, when thecam phase actuator 254 is adjusted to advance the cylinder valve timing, pressurized oil is fed from thepump 220 through thefirst control valve 224 to thefirst actuator port 256. The oil exhausted from thesecond actuator port 258 is fed through thesecond control valve 226 and thedynamic regeneration valve 202 to thereservoir 222, as shown in bold lines inFigure 7 . - When the pressure at the outlet of the
oil pump 220, sensed by thesensing line 252, does not provide a force on thebottom surface 216 of thevalve member 206 sufficient to overcome the force of theregeneration spring 214, the hybrid camphase control system 200 will be operating in the cam torque actuated mode and the net force acting on the camshaft will be used to adjust thecam phase actuator 254. In the cam torque actuated mode, thevalve member 206 is biased into the first valve member position and oil is re-circulated through the hybrid camphase control system 200. For example, when the net torque on the cam shaft adjusts thecam phase actuator 254 to advance the cylinder valve timing, oil from theoil pump 220 can be fed into thefirst actuator port 256 and oil exhausted from thesecond actuator port 258 is fed through thesecond control valve 226, there-circulation line 264, and thethird check valve 260, as shown in bold lines inFigure 8 . The oil flowing through there-circulation line 264 and thethird check valve 260 is fed back to thefirst actuator port 256. Thus, the oil exhausted from thesecond actuator port 258 is re-circulated to thefirst actuator port 256 and theoil pump 220 only needs to supply enough oil to thefirst port 228 to make up for leakage. This minimizes the effect the hybrid camphase control system 200 has on the pressure in thereservoir 222 and enables the adjustment of thecam phase actuator 254 at low oil pump pressures. - If the engine has dual cam shafts, a second
cam phase actuator 266 is provided for the other cam shaft as shown inFigure 9 . The secondcam phase actuator 266 includes oneactuator port 268 in fluid communication with thefirst workport 232 and anotheractuator port 270 in fluid communication with thesecond workport 244. In this embodiment, thecam phase actuators cam phase actuators cam phase actuator 254 can be designed such that the first andsecond actuator ports second passageways actuator ports second passageways - With reference to
Figures 10 and 11 , a fourth embodiment of a control system that provides a hybrid camphase control system 300 that minimizes its impact on the pressure in the main oil galley of an engine by controlling when the hybrid camphase control system 300 is operating in a cam torque actuated mode or an oil pressure actuated mode, as will be described in great detail below. The hybrid camphase control system 300 can utilize adynamic regeneration valve 302, shown inFigure 10 , which enables the hybrid camphase control system 300 to switch between the cam torque actuated mode and the oil pressure actuated mode when adjusting the cylinder valve timing. Thedynamic regeneration valve 302 includes ahousing 304 and avalve member 306 arranged within thehousing 304. Thehousing 304 defines apressure port 308, aregeneration port 310, and atank port 312. Thevalve member 306 illustrated inFigure 11 is a poppet. Thevalve member 306 is configured to be moveable between a first valve member position (Figure 11 ) where fluid communication is inhibited between theregeneration port 310 and thetank port 312 and a second valve member position where fluid communication is provided between theregeneration port 310 and thetank port 312. Aregeneration spring 314 biases thevalve member 306 towards the first valve member position. Thevalve member 306 includes alower surface 316 in fluid communication with thepressure port 308 andcentral portion 318 in fluid communication with theregeneration port 310. Thecentral portion 318 defines adifferential area 319. As the pressure at thepressure port 308 increases, a force acting on abottom surface 316 of thevalve member 306 will eventually overcome the force of theregeneration spring 314 and thevalve member 306 will move from the first valve member position to the second valve member position. - With reference to
Figure 11 , in the hybrid camphase control system 300, aconventional oil pump 320 feeds fluid from a reservoir 322 (e.g., the engine oil pan) to afirst control valve 324, asecond control valve 326, and thedynamic regeneration valve 302. Thefirst control valve 324 and thesecond control valve 326 are each electrohydraulic, three-way control valves operated by a signal from anengine computer 327. Afirst port 328 of thefirst control valve 324 is in fluid communication with the outlet of theoil pump 320, and afirst check valve 330 is arranged between the outlet of theoil pump 320 and thefirst port 328. Thefirst check valve 330 only allows oil to flow from the outlet of theoil pump 320 to thefirst port 328 and prevents oil from flowing in the opposite direction. In another embodiment, thefirst check valve 330 can be arranged within thefirst control valve 324, similar tocheck valves - When the
first control valve 324 is in a first position illustrated inFigure 11 , thefirst control valve 324 provides fluid communication between thefirst port 328 and afirst workport 332. Thefirst control valve 324 is biased towards the first position by a first spring 334. When afirst solenoid actuator 336 is energized by an electric current from theengine computer 327, thefirst solenoid actuator 336 overcomes the force of the first spring 334 and thefirst control valve 324 moves into a second position. In the second position, thefirst control valve 324 provides fluid communication between thefirst workport 332 and asecond port 338. Thesecond port 338 is in fluid communication with theregeneration port 310 of thedynamic regeneration valve 302. - A
third port 340 of thesecond control valve 326 is in fluid communication with the outlet of theoil pump 320, and asecond check valve 342 is arranged between the outlet of theoil pump 320 and thethird port 340. Thesecond check valve 342 only allows oil to flow from the outlet of theoil pump 320 to thethird port 340 and prevents oil from flowing in the opposite direction. In another embodiment, thesecond check valve 342 can be arranged within thesecond control valve 326, similar tocheck valves - When the
second control valve 326 is in one position, thesecond control valve 326 provides fluid communication between thethird port 340 and asecond workport 344. Thesecond control valve 326 is biased towards that one position by asecond spring 346. When a second solenoid actuator 348 is activated by an electric current from theengine computer 327, the second solenoid actuator 348 overcomes the force of thesecond spring 346 and thesecond control valve 326 moves into another position illustrated inFigure 11 . In that other position, thesecond control valve 326 provides fluid communication between thesecond workport 344 and afourth port 350. Thefourth port 350 is in fluid communication with theregeneration port 310 of thedynamic regeneration valve 302. - With continued reference to
Figures 10 and 11 , asensing line 352 provides fluid communication between thepressure port 308 of thedynamic regeneration valve 302 and the outlet of theoil pump 320. When the pressure at the outlet of theoil pump 320 does not provide a force on thebottom surface 316 of thevalve member 306 sufficient to overcome the force of theregeneration spring 314, thevalve member 306 is forced into the first valve member position and thedynamic regeneration valve 302 inhibits fluid communication between theregeneration port 310 and thetank port 312 and thus to thereservoir 322. When the pressure at the outlet of theoil pump 320 reaches a sufficient level, the force acting on thebottom surface 316 of thevalve member 306 overcomes the force of theregeneration spring 314 and thevalve member 306 moves to the second valve member position illustrated inFigure 11 . In the second valve member position, thedynamic regeneration valve 302 provides fluid communication between theregeneration port 310 and thetank port 312 and thus to thereservoir 322. - The hybrid cam
phase control system 300 includes acam phase actuator 354 for varying the rotational relationship between the crankshaft and the cam shaft of the engine. Thecam phase actuator 354 can be a conventional, hydraulically actuated device similar to the actuator shown inFigures 1 and 2 . Alternatively or additionally, thecam phase actuator 354 can be configured to operate similar to thecam phase actuator 68 shown inFigure 4 and described above. Thecam phase actuator 354 includes afirst actuator port 356 in fluid communication with thefirst workport 332 and asecond actuator port 358 in fluid communication with thesecond workport 344. The hybrid camphase control system 300 also includes athird check valve 360, afourth check valve 362, and are-circulation line 364. Thethird check valve 360 inhibits fluid communication between thefirst workport 332 and there-circulation line 364, and also inhibits fluid communication between thefirst actuator port 356 and there-circulation line 364. Thefourth check valve 362 inhibits fluid communication between thesecond workport 344 and there-circulation line 364, and also inhibits fluid communication between thesecond actuator port 358 and there-circulation line 364. There-circulation line 364 provides fluid communication between thesecond port 338 and thesecond actuator port 358, and also provides fluid communication between thefourth port 350 and thefirst actuator port 356. - Operation of the hybrid cam
phase control system 300 will be described with reference toFigures 10-13 . It should be understood that the following description of advancing and retarding the cylinder valve timing is for one rotational direction of the crankshaft and, for another rotational direction of the crankshaft, the operation of thefirst control valve 324 and thesecond control valve 326 will be opposite. Thus, the following description is one non-liming example of the operation of the hybrid camphase control system 300. - The hybrid cam
phase control system 300 can adjust thecam phase actuator 354 using either the cam torque actuated mode or the oil pressure actuated mode. Whether the hybrid camphase control system 300 is operating in the cam torque actuated mode or the oil pressure actuated mode, operation of thefirst control valve 324 and thesecond control valve 326 will be the same for the two modes when adjusting thecam phase actuator 354 to advance or retard the cylinder valve timing. - To adjust the
cam phase actuator 354 and advance the cylinder valve timing, thefirst solenoid actuator 336 is de-energized such that thefirst control valve 324 provides fluid communication between thefirst port 328 and thefirst workport 332, and the second solenoid actuator 348 is energized such that thesecond control valve 326 provides fluid communication between thesecond workport 344 and thefourth port 350. This enables oil from theoil pump 320 to be fed into thefirst actuator port 356 and other oil to be drained from thesecond actuator port 358 back to thereservoir 322. - To adjust the
cam phase actuator 354 and retard the cylinder valve timing, thefirst solenoid actuator 336 is energized such that thefirst control valve 324 provides fluid communication between thefirst workport 332 and thesecond port 338, and the second solenoid actuator 348 is de-energized such that thesecond control valve 326 provides fluid communication between thethird port 340 and thesecond workport 344. This enables oil from theoil pump 320 to be fed into thesecond actuator port 358 and other oil to be drained from thefirst actuator port 356 back to thereservoir 322. - Switching between the cam torque actuated mode and the oil pressure actuated mode is governed by the pressure at the outlet of the
oil pump 320. When the pressure at the outlet of theoil pump 320, sensed by thesensing line 352, provides a force on thebottom surface 316 of thevalve member 306 that overcomes the force of theregeneration spring 314, the hybrid camphase control system 300 will be operating in the oil pressure actuated mode and pressurized oil provided by theoil pump 320 will be used to adjust thecam phase actuator 354. In the oil pressure actuated mode, thevalve member 306 is forced into the second valve member position and oil flowing from either thefirst workport 338 or the second workport 350 (depending on whether the cylinder valve timing is being advanced or retarded) is allowed to flow though thedynamic regeneration valve 302 to thereservoir 322. For example, when thecam phase actuator 354 is adjusted to advance the cylinder valve timing, pressurized oil is fed from thepump 320 through thefirst control valve 324 to thefirst actuator port 356. The oil exhausted from thesecond actuator port 358 is fed through thesecond control valve 326 and thedynamic regeneration valve 302 to thereservoir 322, as shown in bold lines inFigure 11 . - As described above, the
valve member 306 is in the second valve member position while the hybrid camphase control system 300 is operating in the oil pressure assisted mode. During this operation, thedifferential area 319 defined by thecentral portion 318 of thevalve member 306 enables thevalve member 306 to increase or decrease a flow area between theregeneration port 310 and thetank port 312 in response to the pressure at theregeneration port 310. For example, if there is a spike in the pressure at theregeneration port 310, the illustrateddifferential area 319 enables thevalve member 306 to increase the flow area between theregeneration port 310 and thetank port 312 as thevalve member 306 lifts in response to the pressure spike. This functionality of thevalve member 306 is illustrated by aregeneration sensing line 365 inFigures 11-14 . In particular,Figure 12 illustrates, in bold lines, the above described example where the hybrid camphase control system 300 is operating in the oil pressure actuated mode and the pressure at theregeneration port 310 further forces thevalve member 306 to lift and increase the flow area between theregeneration port 310 and thetank port 312. - One skilled in the art will appreciate that the
differential area 319 may be designed to either provide additional flow area between theregeneration port 310 and thetank port 312 during a spike in pressure at theregeneration port 310 or provide additional closing of the flow area between theregeneration port 310 and thetank port 312 during a spike in pressure at theregeneration port 310, compared to thedifferential area 319 illustrated inFigure 10 . Thus, thedifferential area 319 can be designed to reduce the resistance of the hydraulic circuit illustrated inFigures 11-14 and provide faster shifting rates by providing additional flow area. Alternatively, thedifferential area 319 can be designed to ensure that the hybrid camphase control system 300 will default to the oil pressure actuated mode if consistent pressure spikes at theregeneration port 310 stop occurring. - When the pressure at the outlet of the
oil pump 320, sensed by thesensing line 352, does not provide a force on thebottom surface 316 of thevalve member 306 sufficient to overcome the force of theregeneration spring 314, the hybrid camphase control system 300 will be operating in the cam torque actuated mode and the net force acting on the camshaft will be used to adjust thecam phase actuator 354. In the cam torque actuated mode, thevalve member 306 is biased into the first valve member position and oil is re-circulated through the hybrid camphase control system 300. For example, when the net torque on the cam shaft adjusts thecam phase actuator 354 to advance the cylinder valve timing, oil from theoil pump 320 can be fed into thefirst actuator port 356 and oil exhausted from thesecond actuator port 358 is fed through thesecond control valve 326, there-circulation line 364, and thethird check valve 360, as shown in bold lines inFigure 13 . The oil flowing through there-circulation line 364 and thethird check valve 360 is fed back to thefirst actuator port 356. Thus, the oil exhausted from thesecond actuator port 358 is re-circulated to thefirst actuator port 356 and theoil pump 320 only needs to supply enough oil to thefirst port 328 to make up for leakage. This minimizes the effect the hybrid camphase control system 300 has on the pressure in thereservoir 222 and enables the adjustment of thecam phase actuator 354 at low oil pump pressures. - If the engine has dual cam shafts, a second
cam phase actuator 366 is provided for the other cam shaft as shown inFigure 14 . The secondcam phase actuator 366 includes oneactuator port 368 in fluid communication with thefirst workport 332 and anotheractuator port 370 in fluid communication with thesecond workport 344. In this embodiment, thecam phase actuators cam phase actuators cam phase actuator 354 can be designed such that the first andsecond actuator ports second passageways actuator ports second passageways - The foregoing description was primarily directed to one or more embodiments of the invention. Although some attention has been given to various alternatives within the scope of the invention, it is anticipated that one skilled in the art will likely realize additional alternatives that are now apparent from disclosure of embodiments of the invention. Accordingly, the scope of the invention should be determined from the following claims and not limited by the above disclosure.
Claims (15)
- A control system for varying cylinder valve timing of an internal combustion engine, the internal combustion engine includes a pump, a reservoir, a crankshaft, and a camshaft; said control system comprising:a cam phase actuator for adjusting a rotational phase of the camshaft relative to the crankshaft and having a first actuator port and a second actuator port;at least one control valve including at least two ports, the at least one control valve to selectively provide fluid communication between one or more of the pump and the first actuator port, the pump and the second actuator port, the first actuator port and the reservoir, and the second actuator port and the reservoir; anda dynamic regeneration valve arranged between one of the at least two ports and the reservoir, wherein the dynamic regeneration valve is configured to switch operation of the cam phase actuator between an oil pressure actuated mode and a cam torque actuated mode based on a pressure at an outlet of the pump.
- The control system as recited in claim 1 wherein the at least one control valve including at least two ports comprises:a first control valve comprising a first port operatively connected to receive fluid from the pump, a second port, and a first workport in fluid communication with the first port of the cam phase actuator, the first control valve having a first position in which fluid communication is provided between the first port and the first workport, and having a second position in which fluid communication is provided between the second port and the first workport; anda second control valve comprising a third port operatively connected to receive fluid from the pump, a fourth port, and a second workport in fluid communication with the second actuator port, the second control valve having one position in which fluid communication is provided between the third port and the second workport, and having another position in which fluid communication is provided between the fourth port and the second workport.
- The control system as recited in claim 2 further comprising a first check valve operatively connected to restrict fluid to flow only in a direction from the pump to the first port, and a second check valve operatively connected to restrict fluid to flow only in a direction from the pump to the third port.
- The control system as recited in claim 2 further comprising a third check valve operatively connected to restrict fluid to flow only in a direction from the second port of the first control valve to the second actuator port.
- The control system as recited in claim 2 further comprising a fourth check valve operatively connected to restrict fluid to flow only in a direction from the fourth port of the second control valve to the first actuator port.
- The control system as recited in claim 1 wherein the dynamic regeneration valve comprises a housing and a valve member received within the housing and moveable between a first valve member position and a second valve member position, the housing defining a pressure port, a regeneration port, and a tank port.
- The control system as recited in claim 6 wherein when the cam phase actuator is operating in the cam torque actuated mode, the valve member is in the first valve member position where fluid communication is inhibited between the regeneration port and the tank port.
- The control system as recited in claim 6 wherein when the cam phase actuator is operating in the oil pressure actuated mode, the valve member is in the second valve member position where fluid communication is provided between the regeneration port and the tank port.
- The control system as recited in claim 6 wherein the valve member is a spool.
- The control system as recited in claim 6 wherein the valve member is a poppet.
- The control system as recited in claim 6 wherein the valve member includes a portion defining a differential area.
- The control system as recited in claim 11 wherein when the valve member is in the second valve member position, the differential area enables the valve member to increase or decrease a flow area between the regeneration port and the tank port in response to changes in the pressure at the outlet of the pump and/or changes in a pressure at the regeneration port.
- The control system as recited in claim 6 wherein the valve member is biased towards the first valve member position by a biasing member.
- The control system as recited in claim 13 wherein when the cam phase actuator is operating in the cam torque actuated mode, the pressure at the outlet of the pump does not provide a force on the valve member sufficient to overcome a force of the biasing member and the valve member is biased towards the first valve member position by the biasing member.
- The control system as recited in claim 13 wherein when the cam phase actuator is operating in the oil pressure actuated mode, the pressure at the outlet of the pump provides a force on the valve member sufficient to overcome a force of the biasing member and the valve member is moved to the second valve member position.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US14/808,685 US9797276B2 (en) | 2013-03-11 | 2015-07-24 | System for varying cylinder valve timing in an internal combustion engine |
Publications (2)
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EP3121396A1 true EP3121396A1 (en) | 2017-01-25 |
EP3121396B1 EP3121396B1 (en) | 2019-09-11 |
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EP16275101.0A Active EP3121396B1 (en) | 2015-07-24 | 2016-07-14 | System for varying cylinder valve timing in an internal combustion engine |
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EP (1) | EP3121396B1 (en) |
JP (1) | JP2017025919A (en) |
CN (1) | CN106368759B (en) |
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AT16251U1 (en) * | 2018-01-22 | 2019-05-15 | Hp3 Real Gmbh | Tamping unit for a tamping machine |
JP2019157853A (en) * | 2018-03-07 | 2019-09-19 | ボーグワーナー インコーポレーテッド | Zero pressure unlocking system for phaser |
CN110966062B (en) * | 2018-09-30 | 2022-09-27 | 现代自动车株式会社 | Control system and control method for hydraulic variable valve |
JP2023503340A (en) * | 2019-11-27 | 2023-01-27 | ピアッジオ エ チ.ソシエタ ペル アチオニ | Camshaft with phasing device for multi-cylinder internal combustion engines with poppet valves |
Citations (4)
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DE19844669A1 (en) * | 1998-09-29 | 2000-03-30 | Linde Ag | Hydrostatic drive system for mechanical excavator maximises operational reliability while minimising power losses |
EP1400661A1 (en) * | 2002-09-19 | 2004-03-24 | BorgWarner Inc. | Spool valve controlled VCT locking pin release mechanism |
WO2007107426A1 (en) * | 2006-03-17 | 2007-09-27 | Hydraulik-Ring Gmbh | Hydraulic circuit, in particular for camshaft adjuster, and corresponding control element |
DE102013213132A1 (en) * | 2013-07-04 | 2015-01-08 | Schaeffler Technologies Gmbh & Co. Kg | Camshaft adjustment device |
Family Cites Families (5)
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JP4459826B2 (en) * | 2005-01-26 | 2010-04-28 | 株式会社デンソー | Valve timing adjustment device |
JP4524672B2 (en) * | 2006-01-10 | 2010-08-18 | アイシン精機株式会社 | Valve timing control device |
CN201218116Y (en) * | 2008-05-27 | 2009-04-08 | 芜湖杰锋汽车动力***有限公司 | Variable valve timing distribution regulating mechanism |
DE102008002461A1 (en) * | 2008-06-17 | 2009-12-24 | Robert Bosch Gmbh | Device for changing the rotational angle position of a camshaft |
DE102011077587A1 (en) * | 2011-06-16 | 2012-12-20 | Schaeffler Technologies AG & Co. KG | Phaser |
-
2016
- 2016-07-14 EP EP16275101.0A patent/EP3121396B1/en active Active
- 2016-07-22 JP JP2016144925A patent/JP2017025919A/en active Pending
- 2016-07-22 CN CN201610584355.9A patent/CN106368759B/en active Active
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19844669A1 (en) * | 1998-09-29 | 2000-03-30 | Linde Ag | Hydrostatic drive system for mechanical excavator maximises operational reliability while minimising power losses |
EP1400661A1 (en) * | 2002-09-19 | 2004-03-24 | BorgWarner Inc. | Spool valve controlled VCT locking pin release mechanism |
WO2007107426A1 (en) * | 2006-03-17 | 2007-09-27 | Hydraulik-Ring Gmbh | Hydraulic circuit, in particular for camshaft adjuster, and corresponding control element |
DE102013213132A1 (en) * | 2013-07-04 | 2015-01-08 | Schaeffler Technologies Gmbh & Co. Kg | Camshaft adjustment device |
Also Published As
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CN106368759A (en) | 2017-02-01 |
JP2017025919A (en) | 2017-02-02 |
EP3121396B1 (en) | 2019-09-11 |
CN106368759B (en) | 2020-08-04 |
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