Classifications

• • 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
  • F01L9/00—Valve-gear or valve arrangements actuated non-mechanically
  • F01L9/20—Valve-gear or valve arrangements actuated non-mechanically by electric means
• • 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
  • F01L13/00—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations
  • F01L13/06—Modifications of valve-gear to facilitate reversing, braking, starting, changing compression ratio, or other specific operations for braking

Definitions

• the present invention relates to methods and apparatus for actuating an engine valve in an internal combustion engine to achieve a compression-release braking event, a bleeder type engine braking event, and/or an internal exhaust gas recirculation (EGR) event.
• EGR exhaust gas recirculation
• the exhaust valves may be selectively opened to convert, at least temporarily, a power producing internal combustion engine into a power absorbing air compressor.
• a piston travels upward during its compression stroke, the gases that are trapped in the cylinder are compressed. The compressed gases oppose the upward motion of the piston.
• at least one engine valve that communicates with the exhaust manifold may be opened to release the compressed gases, preventing the energy stored in the compressed gases from being returned to the engine on the subsequent expansion down-stroke. In doing so, the engine develops retarding power to help slow the vehicle down.
• the engine valves are typically driven by fixed profile cams, more specifically, by one or more fixed lobes on each of the cams.
• the use of fixed profile cams makes it difficult to adjust the timing and/or magnitude of the engine valve lift needed to optimize engine performance for various engine operating conditions, such as different engine speeds during engine braking.
• Common rail systems may provide virtually limitless adjustment to valve timing because the source of high pressure hydraulic fluid is constantly available for valve actuation. Because common rail systems theoretically may provide almost infinite variation in valve timing, they may be used to carry out almost any type of engine valve event, such as intake, exhaust, compression-release braking, bleeder braking, or exhaust gas recirculation (EGR), so long as the valve being actuated has communication with the appropriate manifold (i.e. the intake or exhaust manifold). Accordingly, given sophisticated and high speed control over the application of this hydraulic pressure, a common rail system should be able to deliver valve actuation on demand for a variety of valve events, as well as provide some control over lift and duration.
• EGR exhaust gas recirculation
• a second significant challenge that arises from the use of common rail systems for engine valve actuation is the potential for failure of the system.
• An hydraulic system suffers from vulnerability to failure as a result of fluid leakage. The greater the extent of leakage prevention measures, the more expensive the system becomes.
• Failure of a common rail system to deliver engine braking and/or EGR would not in and of itself be catastrophic since the vehicle could certainly be operated without these features, albeit sub-optimally. Loss of main intake or main exhaust valve events, however, cannot be tolerated because it results in the complete failure of the engine. Accordingly, there is a need for a common rail system that is responsible only for engine braking and/or EGR valve events, but is not required for main intake or main exhaust engine valve events.
• an innovative engine valve actuation system for engine braking and/or exhaust gas recirculation comprising: a high pressure hydraulic fluid source; a fluid pressure reduction device connected to the high pressure hydraulic fluid source; a hydraulic fluid control valve connected to the fluid pressure reduction device; and an engine valve actuator connected to the hydraulic fluid control valve.
• the present invention is an engine valve actuation system comprising: a high pressure hydraulic fluid passage; a high pressure hydraulic fluid source; a fluid pressure reduction device connected to the hydraulic fluid source through the high pressure hydraulic fluid passage; a low pressure hydraulic fluid passage; a hydraulic fluid control valve connected to the fluid pressure reduction device through the low pressure hydraulic fluid passage; an actuator hydraulic fluid passage; and an engine valve actuator for producing an engine valve event, the engine valve actuator communicating with the hydraulic fluid control valve through the actuator hydraulic fluid passage.
• the present invention is a method for actuating an engine valve in an internal combustion engine to produce an engine valve event.
• the method may comprise the steps of: providing hydraulic fluid to a fluid pressure reduction device; reducing the pressure of the hydraulic fluid from a first pressure to a second pressure; selectively applying the hydraulic fluid at the second pressure to an engine valve actuator; and actuating the engine valve to produce the engine valve event.
• FIG. 1 is a block diagram of an engine valve actuation system according to a first embodiment of the present invention.
• Fig. 2 is a block diagram of an engine valve actuation system according to a second embodiment of the present invention.
• Fig. 3 is a schematic diagram of an engine valve actuation system according to a third embodiment of the present invention.
• FIG. 4 is a block diagram of an engine valve actuation system according to a fourth embodiment of the invention.
• FIG. 5 is a schematic diagram of an engine valve actuation system according to a fifth embodiment of the invention.
• valve actuation system 10 for an internal combustion engine
• the valve actuation system 10 may comprise: a high pressure hydraulic fluid source 100; a fluid pressure reduction device 300 connected to the high pressure hydraulic fluid source 100; a hydraulic fluid control valve 400 connected to the fluid pressure reduction device 300; and an engine valve actuator 600 connected to the hydraulic fluid control valve 400 for actuating an engine valve 700.
• the engine valve 700 may comprise a dedicated braking valve. It is contemplated, however, that the engine valve 700 may comprise an exhaust valve, and/or an intake valve.
• valve actuation system 10 may further comprise an accumulator 500 connected to the hydraulic fluid control valve 400; and a low pressure hydraulic fluid tank 200 connected to the high pressure fluid source 100.
• the valve actuation system 10 includes a high pressure fluid source 100, such as may be used to supply a common rail fuel injection system.
• a high pressure fluid source 100 such as may be used to supply a common rail fuel injection system.
• the hydraulic electronic unit injection (HEUI) system sold by Navistar International is one example of such a common rail fuel injection system.
• the high pressure fluid source 100 may include a high pressure pump 110, a pressure regulator 120, and a high pressure plenum 130.
• the high pressure fluid pump 110 may draw hydraulic fluid, such as diesel fuel, from a low pressure tank 200.
• the fluid pressure provided by pump 110 may be on the order of several thousand (e.g. 3000) psi.
• High pressure fluid sources 100 are known in the art for fuel injection systems.
• the pressure provided by the high pressure fluid source 100 may be indicated by pressure P1.
• the high pressure fluid provided by the source 100 may be used, not only to provide fuel injection, but also to provide a motivating source for engine braking operation.
• One advantage of using the high pressure fluid source, such as source 100, for engine braking is that it is already resident in the engine.
• pressurized fluid from the high pressure fluid source 100 may be provided through a high pressure line 140 to a pressure reducing device 300.
• the pressure reducing device 300 preferably may reduce the pressure of the fluid by approximately a magnitude, and more preferably to a level of approximately 300 psi.
• the reduced pressure fluid may be provided through line 310 to a control valve 400.
• the pressure provided by the pressure reducing device 300 may be indicated by pressure P2.
• the pressure reducing device 300 may comprise a pressure reducing valve.
• the pressure reducing device 300 may comprise a directly- operated pressure reducing valve, a two-way pilot-operated pressure reducing valve, and/or any other known pressure reducing valve.
• other pressure reducing devices adapted to reduce the pressure of the fluid from the high pressure fluid source 100 are considered to be within the scope and spirit of the present invention.
• the control valve 400 may include a valve body 410 and a controller 420.
• the valve body 410 is preferably a 3/2 directional control valve and may include internal passages that connect a first port 412 with a second port 414, and a third port 416 with a fourth port 418.
• the valve body 410 may be biased into a default position by a control valve spring 430.
• the internal passages in the valve body 410 may connect the brake actuator line 440 with an accumulator 500.
• the accumulator 500 may be replaced with a vent or a fluid return line that connects the control valve 400 to the low pressure tank 200.
• the controller 420 may be used to translate the valve body 410 so that fluid flows to and from the brake actuator line 440.
• the valve body 410 may be translated linearly toward the control valve spring 430.
• the controller 420 may be any suitable device for translating the valve body 410 at high speed. It is appreciated that the controller 420 may be a hydraulic, hydroelectric, mechanical, piezoelectric, or electromagnetic (e.g. solenoid) device.
• the controller 420 preferably is capable of translating the valve body 410 at least once, and preferably more than once per engine cycle.
• the controller 420 is preferably controlled by an electrical signal issued by an engine control module (ECM) (not shown).
• ECM engine control module
• the ECM may include a microprocessor, and may be connected to sensors linked to other engine components, such as for example, the engine cylinder, the exhaust manifold, the intake manifold, or any other engine component, to control the controller 420.
• the brake actuator line 440 provides fluid communication between the control valve 400 and the engine valve actuator 600.
• the engine waive actuator 600 includes a fluid chamber 610, an actuator piston 620 disposed to slide in the fluid chamber, and a return spring 630.
• the return spring 630 is shown inside of the fluid chamber 610, however, it is appreciated that the return spring may be provided at any location between the engine valve actuator 600 and the engine cylinder (not shown). The return spring 630 may even be provided as a return spring for the dedicated brake valve 700 since return of the dedicated brake valve 700 to its up most position will also return the actuator piston 620 to its up most position.
• the actuator piston 620 may terminate in an engine valve head, or alternatively, actuate an engine valve 700 dedicated to the braking and/or exhaust gas recirculation function.
• the engine valve 700 provides selective communication between an engine cylinder 720 and an exhaust manifold 710.
• the return spring 630 may bias the actuator piston 620 toward the upper end of the fluid chamber 610. In this position the dedicated engine valve 700 is closed.
• the control valve 400 may assume two primary positions under the influence of the controller 420.
• a first position of the control valve 400 corresponds to the condition in which no engine braking and/or exhaust gas recirculation is desired, i.e. the dedicated engine valve 700 is closed.
• the controller 420 maintains the valve body 410 in the position shown in Fig. 3.
• the first port 412 of the valve body 410 communicates with the brake actuator line 440 and the second port 414 communicates with the accumulator 500.
• the valve body 410 provides communication between the fluid chamber 610 and the accumulator 500.
• Fluid pressure in the accumulator 500 is low, and, accordingly, the dedicated engine valve return spring (which may be spring 630) can displace the actuator piston 620 upward to push fluid out of the fluid chamber 610 and into the accumulator 500. No new fluid may flow into the fluid chamber 610 to displace the actuator piston 620 downward because the control valve 400 is not in a position in which it provides communication between the reduced pressure line 310 and the brake actuator line 440.
• the dedicated engine valve return spring which may be spring 630
• the actuator piston 620 may be displaced downward to actuate the dedicated engine valve 700 as a result of application of reduced pressure fluid from the control valve 400 on the actuator piston.
• the dedicated engine valve is open and gas is free to flow between the engine cylinder associated with the dedicated engine valve and the exhaust manifold.
• the system may be turned "on" for braking, EGR, or other valve actuation duty by applying reduced fluid pressure from the pressure reducing device 300 to the reduced pressure line 310.
• the controller 420 may be instructed to translate the valve body 410 downward. This downward translation causes the third port 416 of the valve body to align with the reduced pressure line 310, and the fourth port 418 to align with the brake actuator line 440.
• the valve body 410 provides fluid communication between the reduced pressure line 310 and the brake actuator line 440. This communication causes the brake actuator piston 620 to translate downward and open the engine valve 700 for an engine braking or exhaust gas recirculation event.
• the foregoing cycle of opening and closing the engine valve 700 may be carried out as quickly as the controller 420 can cause the fluid chamber 610 to drain and refill. It is apparent that the speed of the system will depend upon the speed and size of the control valve 400, the size and length of the brake actuator line 440 and the viscosity of the working fluid. Accordingly, it may be advantageous to locate the control valve 400 as close as possible to the fluid chamber 610 to improve the response time of the system. For some embodiments of the invention, It is desired that the system be capable of more than one engine valve event per engine cycle, and that the system provide an almost infinite variety of timing selections for the opening, closing, and duration of braking and EGR events.
• the system need not always be operated at a high speed to provide beneficial results.
• the system 10 could be used to provide partial or full cycle bleeder braking during times that braking noise is a concern (in a town or city), and to provide compression release type braking at other times when noise is of less concern.
• a reduced fluid pressure (i.e., on the order of 300 psi as opposed to 3000 psi) for the actuation of the dedicated engine braking valve 700 may provide several advantages.
• Advantages realized during braking and/or EGR include the fact that a high-speed trigger valve used as control valve 400 may be easier to make and more reliable because it need only handle reduced pressure fluid.
• the use of reduced pressure fluid may also reduce the impact load and seating velocity of the braking components and make such loads and velocities more controllable.
• the use of reduced pressure fluid may reduce fluid leakage and vibration of the braking system, and make the overall system more compact.
• Advantages realized during positive power include near infinite variation of valve timing to provide internal EGR tailored to engine speed and/or load.
• the system 10 could also be modified to provide cooled internal EGR since the exit passage for the dedicated valve can be different from that for the main exhaust valves and a cooler can be provided in the dedicated passage.
• FIG. 5 An alternative embodiment of the present invention is shown in Fig. 5, in which like reference numerals refer to like elements.
• the engine valve actuator 600 is provided by an electromagnetic actuator 690.
• the system of Fig. 5 may be operated similarly to the system shown in Fig. 3.
• the electromagnetic actuator 690 may comprise a highspeed solenoid valve capable of actuating the engine valve 700 at a rate of at least once per engine cycle. In another embodiment, the electromagnetic actuator 690 may comprise a low-speed solenoid valve. Other embodiments of the engine valve actuator 600, including, but not limited to, a piezoelectric actuator are considered within the scope and spirit of the present invention.
• the dedicated engine valve 700 for engine braking and EGR may be smaller than the main exhaust valve and may need less force to open it. Once the valve is fully open, the flow area through the valve is controlled by the annular gap between the bore and the valve stem, and even less force may be needed to keep the valve open.
• embodiments of the methods and apparatus of the present invention may be adapted for two-stroke engine braking, in which the normal engine exhaust and intake valve events are modified, as well as four-stroke engine braking.
• the present invention cover all such modifications and variations of the invention, provided they come within the scope of the appended claims and their equivalents.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Valve Device For Special Equipments (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)
• Exhaust-Gas Circulating Devices (AREA)

Applications Claiming Priority (3)

Publications (1)

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• 2003
  • 2003-01-30 KR KR10-2004-7011884A patent/KR20040094419A/ko not_active Application Discontinuation
  • 2003-01-30 EP EP03735064A patent/EP1483484A2/de not_active Withdrawn
  • 2003-01-30 US US10/353,717 patent/US20030140876A1/en not_active Abandoned
  • 2003-01-30 JP JP2003564398A patent/JP2005516144A/ja active Pending
  • 2003-01-30 CN CNB038075997A patent/CN100379951C/zh not_active Expired - Fee Related
  • 2003-01-30 WO PCT/US2003/002634 patent/WO2003064820A2/en active Application Filing

Non-Patent Citations (1)

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