EP4069959A1 - Hydraulic control system for a variable compression ratio engine - Google Patents
Hydraulic control system for a variable compression ratio engineInfo
- Publication number
- EP4069959A1 EP4069959A1 EP20841973.9A EP20841973A EP4069959A1 EP 4069959 A1 EP4069959 A1 EP 4069959A1 EP 20841973 A EP20841973 A EP 20841973A EP 4069959 A1 EP4069959 A1 EP 4069959A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- hydraulic
- hydraulic control
- engine
- chambers
- control system
- 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.)
- Withdrawn
Links
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- 238000007906 compression Methods 0.000 title claims abstract description 52
- 239000012530 fluid Substances 0.000 claims abstract description 50
- 238000004891 communication Methods 0.000 claims abstract description 24
- 238000002485 combustion reaction Methods 0.000 claims description 35
- 238000006073 displacement reaction Methods 0.000 claims description 9
- 230000008878 coupling Effects 0.000 claims description 7
- 238000010168 coupling process Methods 0.000 claims description 7
- 238000005859 coupling reaction Methods 0.000 claims description 7
- 230000000903 blocking effect Effects 0.000 abstract description 3
- 238000007599 discharging Methods 0.000 abstract 1
- 239000003921 oil Substances 0.000 description 53
- 230000008859 change Effects 0.000 description 14
- 238000005461 lubrication Methods 0.000 description 10
- 125000006850 spacer group Chemical group 0.000 description 9
- 230000006641 stabilisation Effects 0.000 description 5
- 238000011105 stabilization Methods 0.000 description 5
- 230000010355 oscillation Effects 0.000 description 4
- 230000000750 progressive effect Effects 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
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- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000036316 preload Effects 0.000 description 3
- 230000002441 reversible effect Effects 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000010354 integration Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 239000010705 motor oil Substances 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000011001 backwashing Methods 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005553 drilling Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 230000008929 regeneration Effects 0.000 description 1
- 238000011069 regeneration method Methods 0.000 description 1
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- 230000000087 stabilizing effect Effects 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D15/00—Varying compression ratio
- F02D15/02—Varying compression ratio by alteration or displacement of piston stroke
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
- F02B75/045—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of a variable connecting rod length
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B75/00—Other engines
- F02B75/04—Engines with variable distances between pistons at top dead-centre positions and cylinder heads
- F02B75/048—Engines with variable distances between pistons at top dead-centre positions and cylinder heads by means of a variable crank stroke length
Definitions
- the present invention relates to the field of variable compression ratio engines. It relates in particular to a hydraulic system for controlling said rate, supplied by the engine lubrication circuit, which system is provided with an independent means of pressurizing the oil ensuring an average hydraulic pressure in the hydraulic control circuit constantly greater than engine lubrication pressure during engine operation.
- Variable compression ratio engines are known in which the said rate control system, operating individually for each combustion cylinder, is based on a hydraulic cylinder.
- the continuous rate VCRi engine developed by the applicant, and the so-called two-rate connecting rod systems developed in particular by the FEV or AVL companies.
- VCRi engine operates at pressures of up to 300 bars, while two-rate connecting rod systems can operate at pressures of up to more than 2000 bars.
- Oil is a compressible fluid, especially since it is loaded with gas (engine oil is conventionally aerated between 5% and 30% depending on the operating conditions).
- This elasticity measured by the isostatic modulus of elasticity (otherwise called bulk modulus), results in a modification of the position of the control cylinder as a function of the force applied, which causes oscillations in the system, leading to an amplification of the forces by dynamic effect, and adversely affects the precision desired for the control of the compression ratio.
- the company FEV (“2-step variable compression ratio System development & industrialization”, 2 nd International FEV ConfInter, Feb 7-8, 2019) proposes to use a special distributor to ensure the pressure increase in the hydraulic chamber of the control system, by pumping effect.
- a rate change which will result in the opening of the distributor, will drop the pressure in the control system to the supply pressure (lubrication circuit): this implies that the module of The isostatic elasticity of the oil will not be optimal at least for a few cycles, which may lead to temporary overloads of the kinematics (amplification phenomena due to shocks).
- Document JP2003 / 322036 proposes a mechanism for a variable compression ratio engine comprising electrical means for controlling the control shaft in rotation and a hydraulic holding means making it possible to reduce the forces applied to the control means and avoiding to supply them continuously with energy.
- Document FR2914951 proposes an electro-hydraulic device for controlling a closed loop of a control cylinder for an engine with a variable compression ratio.
- the present invention provides an alternative solution to those of the state of the art, remedying all or part of the aforementioned drawbacks. It relates in particular to a hydraulic control system comprising a control cylinder and a hydraulic control circuit, and the architecture of which makes it possible to increase the average pressure in the hydraulic chambers of the control cylinder to values greater than the lubrication pressure. , and typically greater than 20 bars, and to maintain said average pressure during changes in the compression ratio of the engine.
- the invention relates to a hydraulic control system for a variable compression ratio engine comprising:
- control cylinder comprising a piston and a body in which two hydraulic chambers of equivalent sections are defined on either side of the piston, said piston being able to move in the body to control the compression ratio of the engine
- a hydraulic control circuit comprising at least one conduit connecting the two hydraulic chambers to one another, and a controlled fluidic distribution device to establish or block fluidic communication between said chambers,
- the hydraulic control system is remarkable in that:
- the hydraulic control circuit comprises:
- the control cylinder comprises a return device tending to bring said cylinder to a length corresponding to a maximum compression ratio of the engine.
- the hydraulic control system makes it possible to supply the hydraulic control circuit by means of a low pressure oil supply, typically connected to the engine lubrication circuit (low pressure, between 2 and 6 bars for example. ), thanks to the conduit connecting at least one of the hydraulic chambers and a low pressure oil supply. It also makes it possible to increase the average pressure in the hydraulic chambers of the control cylinder to values greater than the lubrication pressure, and typically greater than 20 bars, due to the presence of the first non-return valve which allows the rewashing of the hydraulic circuit when the combustion and / or inertia forces applied to the jack sequentially cause pressure drops in the chamber connected to the supply.
- the hydraulic control system makes it possible to maintain this average pressure, typically greater than 20 bars, in the hydraulic chambers, during the rate change operation.
- the presence of the first regwashing non-return valve prevents the hydraulic control circuit from dropping down to low supply pressure, by isolating it from said supply whatever the operating conditions of the engine.
- the rate change linked to the displacement of the piston in the body of the control cylinder, is defined by the controlled fluid distribution device which manages the circulation and transfer of oil from one chamber to the other, and thus the piston position. The accuracy of the rate setting is thus improved because the hydraulic control system operates in pressure ranges above the stabilization pressure of the bulk module.
- the hydraulic control system according to the invention makes it possible to regulate the average pressure in the hydraulic chambers and it allows the effective attainment of the variable compression ratios between minimum rate and maximum rate, as well as an effective rate change, that is to say with a good dynamic, between minimum rate and maximum rate, or vice versa.
- the pipe fitted with the relief valve connects the oil discharge and the chamber, among the two hydraulic chambers, which is not subjected to combustion forces from the engine,
- the return device is placed in the chamber, among the two hydraulic chambers, which undergoes combustion forces from the engine,
- the hydraulic control circuit is carried by the body of the control cylinder;
- the controlled fluid distribution device is actuated by an electrical control circuit
- the controlled fluid distribution device is actuated by a hydraulic control circuit
- the fluidic distribution device comprises a two-position controlled shutter, one position of which blocks the fluidic communication between the two chambers and the other position allows fluidic communication between the two chambers, in both directions of circulation;
- the hydraulic control circuit comprises at least two conduits connecting the two hydraulic chambers to each other, and in which the fluid distribution device comprises two controlled two-position shutters and two oriented valves, a first shutter and a first oriented valve being carried by a first duct, to block or allow the circulation of oil from the first chamber to the second chamber, and a second shutter and a second oriented valve being carried by a second duct, to block or allow the circulation of oil from the second bedroom to the first bedroom;
- Each controlled shutter is arranged along a transverse axis, normal to a longitudinal axis of displacement of the piston in the body of the control cylinder;
- the piston of the control cylinder is intended to be connected to a return member of a movable coupling of the engine, and the body of the control cylinder is intended to be connected to a fixed part of the engine.
- Figure 1 shows a curve relating the isostatic modulus of elasticity of oils to pressure
- Figure 2 shows a block diagram of a hydraulic control system according to a first embodiment, according to the invention
- Figures 3a and 3b respectively show a block diagram of a hydraulic control system according to a second embodiment, according to the invention, and various options for the rest position of the fluid distribution device in a hydraulic control system according to the second embodiment;
- Figures 4a and 4b show curves illustrating the operation of a control system according to the state of the art, with pressure drop at each rate change and respectively without and with oil backwashing of the hydraulic control system;
- Figures 6a, 6b, 6c, 6d, 6e show a particular example of implementation of the hydraulic control system, according to the second embodiment of the invention.
- FIG. 7 shows a mobile coupling and a system for controlling the variable compression ratio in an engine according to the state of the art
- Figure 8 shows a side view of a mobile coupling and a hydraulic control system of a variable compression ratio engine, said system being in accordance with the invention.
- the present invention relates to a hydraulic control system 3 for a variable compression ratio engine, two embodiments of which are illustrated respectively in FIG. 2 and in FIG. 3a.
- the control system 3 comprises a control cylinder 30 comprising a piston 30a and a body 30b in which two hydraulic chambers 31, 32 of equivalent sections are defined on either side of the piston 30a.
- a control cylinder 30 comprising a piston 30a and a body 30b in which two hydraulic chambers 31, 32 of equivalent sections are defined on either side of the piston 30a.
- Figures 2 and 3a are schematic and do not illustrate the equivalent nature of the sections of the two chambers 31, 32.
- Said piston 30a is able to move in the body 30b, which modifies the length of the cylinder and defines (or in other words, controls) the compression ratio of the engine.
- control system 3 could be integrated into a connecting rod of variable length, directly connected to the combustion piston and to the crankshaft of an engine with variable combustion rate. It can also be integrated into a VCRi type control jack. Finally, as will be described in more detail in one example below, such a control system 3 can be integrated into a VC-T type engine (for “variable compression - turbo”) described in document EP2787196.
- the hydraulic control system 3 also comprises a hydraulic control circuit 37 whose role is in particular to supply the hydraulic chambers 31, 32 of the control cylinder 30 with oil and to manage the transfer of oil from one chamber to 1 '. other.
- the hydraulic control circuit 37 comprises at least one conduit 37a, 37b, 37c connecting the two hydraulic chambers 31, 32 to one another. Subsequently, this or these conduits 37a, 37b, 37c will be called transfer conduits 37a, 37b, 37c because they allow the circulation of oil from one chamber 31, 32 to the other.
- the hydraulic control circuit 37 also comprises a fluidic distribution device 371a, 372 disposed on said (at least one) transfer duct 37a, 37b, 37c, between the two hydraulic chambers 31, 32.
- the fluidic distribution device 371a, 372 is controlled to establish or block a fluidic communication between said chambers 31, 32; in other words, said device 371a, 372 is controlled to open or close the duct (s) 37a, 37b, 37c connecting the two chambers 31, 32.
- the transfer conduits 37a, 37b, 37c and the fluid distribution device 371a, 372 make it possible to manage the transfer of oil from one hydraulic chamber 31, 32 to the other, and thus to modify the length of the control cylinder 30. , corresponding to a modification of the engine compression ratio.
- the hydraulic control circuit 37 also comprises at least one conduit 37d connecting at least one of the hydraulic chambers 31, 32 to a supply of oil 60 at low pressure.
- a first non-return valve 373 is arranged on said conduit 37d: it only allows the passage of oil from the oil supply 60 to the hydraulic chamber 31, 32, when the pressure in said hydraulic chamber drops below the oil supply pressure. In practice, the oil pressure from the supply 60 is between 2 and 6 bars. Because pipe 37d and the first non-return valve 373 allow the hydraulic circuit to be rewashed with oil 37, they may be called respectively subsequently, rewashing duct 37d and rewashing valve 373.
- the regwashing duct 37d and the regwashing valve 373 are arranged between the oil supply 60 and that of the two hydraulic chambers 32 which is not subjected to the combustion forces of the engine.
- the forces generated by the combustion being greater than those generated by the inertias, the hydraulic chamber 32 will see the greatest depression and the lowest instantaneous pressure, thus improving the regavage.
- the hydraulic control circuit 37 makes it possible to increase the average pressure in the hydraulic chambers 31, 32 of the control cylinder 30 to values greater than the lubrication pressure (low pressure), and typically greater than 20 bars, or even greater than 30. bars. This is made possible by the presence of the rewash valve 373 which allows the introduction of oil into the hydraulic control circuit 37, when the combustion and / or inertia forces applied to the cylinder 30 sequentially cause drops of pressure in the chamber connected to the supply.
- the hydraulic control circuit 37 makes it possible to maintain this average pressure, typically greater than 20 bars, in the hydraulic chambers 31, 32, during the rate change operation.
- the regavage valve 373 prevents the hydraulic control circuit 37 from falling back to the low supply pressure, by isolating it from said supply, whatever the operating conditions of the engine.
- the rate change, linked to the movement of the piston 30a in the control cylinder 30, is defined by the piloted fluid distribution device 371a, 372 which manages the circulation and transfer of oil from a chamber towards the other, and thus the position of the piston 30a in the body 30b of the control cylinder 30.
- FIG. 4a illustrates the operation of a hydraulic control system close to the state of the art, that is to say undergoing a loss of power. pressure during compression ratio changes; in FIG. 4a, the system does not have an oil regeneration function, while in FIG. 4b, the system is provided with it.
- FIG. 5 illustrates the operation of a hydraulic control system according to the present invention, not undergoing a loss of pressure during changes in compression ratio and comprising a function of rewashing the hydraulic chambers 31, 32 with oil.
- the engine In both cases, the engine is operating under conditions of 1000 revolutions per minute and having a maximum pressure in the combustion cylinder of 32 bars.
- the average pressure in the hydraulic chambers is calculated over an engine cycle (0.12 s).
- the rate setpoint is defined as follows: +1 requests an increase in the compression ratio, 0 requests a fixed rate, -1 requests a decrease in the compression ratio.
- the average pressure in the hydraulic chambers always remains below 10 bars.
- the actual compression ratio obtained oscillates very strongly, typically by more than two points, which makes servo-control impossible.
- the average pressure in the hydraulic chambers can reach values greater than 20 bars in a certain control phase but drop with each change in compression ratio.
- the actual compression ratio obtained oscillates strongly, and takes time to stabilize, which makes the control difficult.
- the average pressure in the hydraulic chambers 31, 32 increases during the first engine cycles and remains greater than 20 bars, or even greater than 30 bars, during the compression ratio change operations.
- the compression rate obtained is much more stable (no or few oscillations) and precise.
- the hydraulic control system 3 according to the invention therefore shows very good performance, even on a very lightly loaded operating point (low engine speed, idling).
- the hydraulic control circuit 37 further comprises at least one conduit 37e connecting at least one of the hydraulic chambers 31, 32 to an oil outlet 70.
- a second non-return valve 374 is disposed on said conduit 37e and allows the drain to be drained. hydraulic control circuit 37 when the pressure in said hydraulic chamber 31, 32 exceeds a determined maximum pressure due to the combustion forces and / or inertia of the engine applying to the cylinder (30).
- the 37th duct and the second non-return valve 374 may respectively be named subsequently, 37th drain duct and 374 drain valve. They make it possible to prevent the average pressure in the hydraulic chambers 31, 32 from being too high and that 'it imposes complex sealing solutions in the control cylinder 30.
- the hydraulic control system 3 could nevertheless operate with a hydraulic control circuit 37 devoid of drain pipe 37e and drain valve 374: the particularity of having hydraulic chambers 31,32 of equivalent sections allows the piloting and the 'servo-control of the system 3, regardless of the average pressure in the chambers 31,32.
- This average pressure would increase to a stabilization level corresponding to the stopping of the regavage function (i.e. when the instantaneous pressure in the hydraulic chamber (s) 31.32 connected to the oil supply 60 via the pipe 37d and the rewash valve 373 no longer goes below the supply pressure).
- the stabilized average pressure could be high, typically greater than 500 bars and would require a seal adapted to the maximum instantaneous pressure levels attainable in the hydraulic chambers 31, 32.
- the hydraulic control circuit 37 is carried by the body 30b of the control cylinder 30.
- the conduits 37a, 37b, 37c, 37d, 37e are formed by drilling in said body 30b; the fluid distribution device 371a, 372 and the first and second non-return valves 373,374 are integrated in the body 30b.
- the oil supply 60 is external to the control cylinder 30, it is typically connected to the engine lubrication circuit.
- the control cylinder 30 comprises a return device 34, tending to bring said cylinder 30 to a length corresponding to the maximum compression ratio. Note that depending on the location of the control cylinder 30 in the engine, the maximum compression ratio may correspond to its minimum or maximum length.
- the control jack 30 At low speed, the combustion forces exerted on the control cylinder 30 (tending to bring the system to minimum rate) are greater than the inertia forces (tending to bring the system to maximum rate). Because of the equivalent sections, the control jack 30 therefore has an easier time going to its position corresponding to minimum rate than to its position corresponding to maximum rate, because there is potentially more effort to do so.
- the return device 34 makes it possible to exert an additional effort (in addition to the inertia forces) to increase the speed of change of length of the jack 30 towards the maximum rate and thus not to penalize fuel consumption and pollution emissions. . As illustrated in the examples of Figures 2 and 3a, the return device 34 is arranged in the hydraulic chamber 31 which is subjected to the combustion forces of the engine.
- the hydraulic control system 3 therefore allows the effective attainment of the variable compression ratios between the minimum rate and the maximum rate, as well as an effective rate change, that is to say. say with a good dynamic, between minimum rate and maximum rate, and vice versa.
- the return device 34 (for example a spring) is typically sized to return the control cylinder 30 from the position (length) corresponding to a minimum compression ratio to the position corresponding to a maximum compression ratio, in less than 2 seconds. , under engine speed conditions of about 1000 revolutions per minute. This dimensioning takes into account the pre-load and the stiffness of the return device 34, in line with the calibration of the pressure drop of (or des) transfer conduits 37a, 37b, 37c connecting the two hydraulic chambers 31, 32 together. Of course, the return device 34 must also allow the rate change to the minimum compression ratio, by the combustion forces, with an acceptable dynamic, typically in less than 0.5 to 0.8 seconds, under conditions. engine speed to approximately 1000 revolutions per minute (rpm).
- a hydraulic control system 3 designed for an engine with variable compression ratio (100), of the type illustrated in FIG. 8, and the kinematics of which leads to a maximum force at l end of the control cylinder 30 of 31kN at 1500rpm for a pressure in the combustion cylinder of 120bar, and 10kN for a combustion pressure of 55bar. At 5500rpm, these forces become 40kN for a combustion pressure of 120bar, and 15kN for a combustion pressure of 55bar.
- the diameter of the piston 30a is chosen at 47mm to limit the pressure in the control cylinder 30 to the maximum force.
- the spring 34 has a preload of 200N, and a stiffness of 50N / mm.
- a calibrated orifice of 2mm between the two hydraulic chambers 31, 32, located on the transfer duct 37c allows, in this configuration, a speed of variation from the maximum rate to the minimum rate of 0.35s at 1500rpm, and of 0.17s at 5500rpm.
- a calibrated 1mm orifice, located on duct 37c, allows a rate variation speed of 0.84s at 1500rpm, and 0.53s at 5500rpm.
- the configuration described previously leads to a rate of rise from the minimum rate to the maximum rate of 1.13s at 1500 rpm, and from 0.37s to 5500 rpm, while a 1mm orifice, located on duct 37b, allows a speed of variation from the minimum rate to the maximum rate of 1.9s at 1500rpm and of 0.67s at 5500rpm.
- the fluidic distribution device 371a comprises a two-position controlled shutter, one position of which blocks the fluidic communication between the two chambers 31, 32 and the other position allows the fluidic communication between the two rooms 31,32, in both directions of circulation.
- This first embodiment is based on synchronous operation of the hydraulic control system 3, that is to say that the control of the fluidic distribution device 371a must be synchronized with the engine cycles.
- the control of the fluidic distribution device 371a must be synchronized with the engine cycles.
- the piston 30a to move the piston 30a towards the maximum length of the cylinder 30 (corresponding for example to a minimum compression ratio)
- the reverse principle must be implemented to move the piston 30a towards the minimum length of the cylinder 30 (corresponding for example to a maximum compression ratio
- the controlled fluidic distribution device 371a must be compatible with a very short switching time, typically 1 ms.
- An electro-hydraulic shutter directly installed in the body of the cylinder 30b, could fulfill this function and would require a wired connection between the mobile cylinder 30 and a fixed motor control.
- a purely hydraulic fluid distribution device, as illustrated in FIG. 2, can also be envisaged. In this case, it is necessary to take into account a time delay for the actuation of the device 371a, due to the oil duct connecting the pilot part 80 of said device.
- the hydraulic control circuit 37 comprises at least two transfer conduits 37b, 37c connecting the two hydraulic chambers 31, 32 to one another.
- the fluidic distribution device 372 comprises two piloted shutters 372b, 372c with two positions, and two oriented valves 372b ', 372c'.
- This second embodiment is based on an asynchronous operation of the hydraulic control system 3, that is to say that the control of the fluidic distribution device 372 is independent of the engine cycles.
- the first shutter 372b allows fluid communication between the chambers 31, 32, while the second shutter 372c blocks fluid communication.
- the combustion and / or inertia forces tend to increase the pressure in the upper chamber 31, an oil transfer takes place from the upper chamber 31 to the lower chamber 32; the progressive filling (with the alternation of the engine cycles) of the lower chamber 32 and the progressive emptying of the upper chamber
- the second shutter 372c is placed in a position allowing fluid communication between the chambers 31, 32, while the first obturator 372b is placed in a position blocking fluid communication. It is thus only possible to transfer oil from the lower chamber 32 to the upper chamber 31; the progressive filling (with the alternation of the engine cycles) of the upper chamber 31 and the progressive emptying of the lower chamber
- each shutter 372b, 372c at rest can be chosen in different ways, according to the preferred strategy in failure of the pilot circuit 80.
- the two shutters 372b, 372c at rest block all fluid communication, which freezes the compression ratio at its value in the event of failure of the pilot circuit 80.
- the shutter 372b in its rest position allows fluid communication from the lower chamber 32 to the upper chamber 31, while the shutter 372c, in its rest position, blocks fluid communication in the reverse direction.
- the length of the control cylinder 30 will gradually vary towards its minimum length. If this minimum length corresponds for example to a maximum compression ratio, this option ensures the best performance and the best efficiency of the engine, limiting the pollution caused, but this reduces the range of use of the engine (limitation in speed and / or in charge).
- the shutter 372c in its rest position allows fluid communication from the upper chamber 31 to the lower chamber 32, while the shutter 372b, in its rest position, blocks fluid communication in the reverse direction.
- the length of the control cylinder 30 will gradually vary towards its maximum length. If this maximum length corresponds for example to a minimum compression ratio, this option makes it possible to maintain the performance of the engine (no limitation in speed and / or load) but reduces its efficiency and its output which increases the pollution produced by the engine. engine.
- control circuit 80 the role of which is to control the fluid distribution device 371a, 372 of the control system 3, two variants are proposed.
- the controlled fluid distribution device 371a, 372 is actuated by an external electrical control circuit.
- an electric wire must connect a fixed part of the motor, in which the electrical control circuit is located, and the fluid distribution device 371a, 372 preferably integrated into the control cylinder 30, which constitutes a movable part in the motor. .
- the controlled fluid distribution device 371a, 372 (which is included in the hydraulic control circuit 37) is actuated by a hydraulic circuit. control 80.
- the fluid distribution device 371a, 372 is tilted from a pass position to a blocking position (and vice versa) by means of the pressure of a fluid issuing from said hydraulic control circuit 80
- This fluid can be water, gas or oil.
- the first and second embodiments of the invention presented respectively in Figures 2 and 3a illustrate a hydraulic control circuit 80 essentially external to the control cylinder 30.
- At least one fluidic channel 81 connects the fluidic distribution device 371a, 372 to the pilot circuit 80.
- the latter may for example comprise an electrically actuated pilot valve 82 making it possible to deliver a fluid pressure in the fluidic channel 81 or to block the arrival of fluid in said channel 81, in order to switch the fluidic distribution device 371a, 372 respectively in one or the other of its positions.
- the pilot valve 82 is connected to the engine lubrication circuit, the fluid is then low pressure oil.
- the fluidic distribution device 371a, 372 can be controlled, therefore actuated, directly by the fluid pressure coming from the pilot circuit 80: it will then be necessary for the fluidic channel 81 to allow direct communication between the pilot fluid and said device 371a, 372.
- the fluidic distribution device 371a, 372 could be actuated mechanically, by a force exerted by a mechanical actuating element, the latter being moved by the fluid pressure coming from the pilot circuit 80.
- each controlled shutter 371a, 372b, 372c of the fluid distribution device 371a, 372 is arranged along a transverse axis T, normal to a longitudinal axis L of displacement of the piston 30a in the body 30b of the control cylinder 30.
- a shutter 371a, 372b, 372c may for example be formed by a linear hydraulic slide whose central axis is parallel to the transverse axis T. This orientation avoids the shutter 371a, 372b, 372c to undergo the inertia and / or combustion forces applied to the control cylinder 30, forces which could interfere with the control forces necessary for actuating the shutters.
- FIGS. 6a to 6e A particular example of the implementation of the hydraulic control system 3 will now be described, with reference to FIGS. 6a to 6e.
- This example is based on the second embodiment previously described, that is to say involving a fluid distribution device 372 comprising two piloted shutters 372b, 372c and two oriented valves 372b ', 372c'. It is also based on controlling the fluid distribution device 372 by mechanical actuation.
- control cylinder 30 with its piston 30a movable in the body 30b.
- the piston 30a is extended by a foot 30a 'extending beyond the body 30b according to a longitudinal axis L, and capable of establishing a pivot connection with a mobile element of the engine.
- a first chamber 31 and a second chamber 32 are defined in the body 30b of the control cylinder 30, on either side of the piston 30a which incorporates seals.
- the first chamber 31 (or upper chamber) is called a “high pressure chamber” because it takes up the combustion forces; in contrast, the second chamber 32 (or lower chamber) is called a “low pressure chamber”.
- the respective filling and emptying of the first 31 and of the second 32 chambers modify the length of the control cylinder 30.
- the body 30b of the control cylinder 30 comprises two coaxial side bearings 35 of transverse axis T normal to the longitudinal axis L (FIG. 6b).
- These lateral bearings 35 are intended to establish a pivot connection with a part of the engine (either fixed integral with the engine block, or mobile, depending on the configuration of integration of the hydraulic control system 3 in the engine).
- the lateral position of said bearings 35 makes it possible to compact the control cylinder 30 with respect to a conventional cylinder with the connection points at the ends, thus limiting the bulk in the engine block.
- each lateral bearing 35 has a shoulder 35a to ensure the positioning of the jack 30, along the transverse axis T, in the engine.
- the control cylinder 30 comprises a spacer 52 attached to each side bearing 35 and intended to be integral with the above-mentioned part of the motor (FIG. 6c).
- the connection between the side bearings 35 and the added spacers 52 allows the oscillating movement of the control cylinder 30 necessary for the operation of the control system 3 in the engine 100.
- each added spacer 52 has a cylindrical internal housing, for this purpose. accommodate a side bearing 35.
- the outer casing of the spacer 52 may also be cylindrical. It may nevertheless be advantageous to provide an ovoid outer casing to block any movement of the rotation of the spacer 52 vis-à-vis the part of the engine to which it is fixed.
- the control cylinder 30 comprises a shouldered ring 53 interposed between each side bearing 35 and its attached spacer 51, to limit the friction associated with the oscillation movement of the control cylinder 30 and to partially take up the combustion forces as well as those of inertia undergone by said jack 30.
- the fluidic distribution device 372 of the hydraulic control circuit 37 comprises a first hydraulic spool 372b and a second hydraulic spool 372c, respectively housed in the first lateral bearing 35 and the second lateral bearing 35 of the cylinder 30 (FIG. 6d).
- the two drawers are arranged along the transverse axis T, coaxially with the side bearings 35.
- a movement along the transverse axis T of the first hydraulic spool 372b makes it possible for example to establish a circulation of oil (shown diagrammatically by the black arrows in FIG. 6d) from the first chamber 31 to the second chamber 32, via first passages 37b arranged in the body 30b of the jack 30.
- the movement of the first slide 372b places the first passages 37b leading to the two chambers 31, 32 in communication, and a first non-return valve 372b 'is arranged on said first passages 37b , allowing only a circulation of fluid from the first chamber 31 to the second chamber 32 (FIG. 6e, (i), (ii)).
- a displacement of the second hydraulic spool 372c makes it possible to establish an oil circulation of the second chamber 32 to the first chamber 31, via second passages 37c arranged in the body 30b.
- the movement of the second slide 372c places the second passages 37c leading to the two chambers 31, 32 in communication, and a second non-return valve 372c 'is disposed on said second passages 37c, allowing only a circulation of fluid from the second chamber 32 to the first chamber 31.
- the system 3 implements a hydraulic pilot circuit 80.
- the pilot circuit 80 is supplied with a pressurized fluid (for example, oil) coming from the part of the valve. motor to which the body 30b is connected.
- each hydraulic slide 372b, 372c is intended to be in contact via a ball 803 with a pilot piston 801,802 carried by the attached spacer 52 (FIG. 6c (ii), FIG. 6d).
- Each pilot piston 801,802 can be moved by the oil pressure (shown schematically by the white arrows in FIG. 6e) in the pilot circuit 80, to induce the displacement of the associated hydraulic spool 372b, 372c.
- the oil from this circuit 80 is conveyed via conduits 81 to an internal housing of each attached spacer 52, which housing accommodates the pilot piston 801,802.
- the mechanical contact between the pilot piston 801,802 and the hydraulic spool 372b, 372c is provided by a ball 803, which is capable of accommodating the oscillation of the jack 30 relative to the other connecting parts of the engine, including in particular relative to the pilot piston 801.802.
- This configuration provides a simple and robust solution for the external piloting of the hydraulic control circuit 37 of the system 3.
- the hydraulic control circuit 37 comprises at least one bore 37d and a rewash valve 373, between an oil supply and the lower chamber 32 (FIG. 6e (i), (iii)).
- Regwash valve 373 is configured so as to allow circulation of oil from the oil supply to the second chamber 32, when the pressure in said chamber 32 is lower than the supply pressure.
- the hydraulic control circuit 37 comprises at least one bore 37e and a relief valve 374 between the second hydraulic chamber 32 and the outside of the cylinder 30, so as to evacuate oil from the control circuit 37, when the pressure in said chamber 32 exceeds a determined maximum pressure.
- a relief valve 374 whose opening pressure is greater than 200 bars or 300 bars, to avoid the implementation of complex sealing solutions in the hydraulic control system 3.
- the hydraulic control system 3, and in particular the system 3 according to the aforementioned example of implementation, is particularly suitable for integration into a variable compression ratio engine of the VCT type.
- VCT motor an implementation of which according to the state of the art is illustrated in FIG. 7, comprises two distinct groups of components:
- the control system 2 integrating the control rods 20, the eccentric shaft 22, the levers 23,25, the rod 24 and the electric control means 26.
- the hydraulic control system 3 can replace the aforementioned control system 2, as illustrated in FIG. 8.
- the piston 30a of the control cylinder 30 is intended to be connected, via its foot 30a 'to a return member of a movable coupling of the engine, and the body 30b of the control cylinder 30 is intended to be connected to a fixed part 51 of the engine.
- the hydraulic control system 3 for an engine with variable compression ratio, comprises one or more control ram (s) as described above.
- the mobile coupling 1 of the VCT-type engine 100, integrating the combustion pistons 10, the main connecting rods 11, the return members 12 and the crankshaft 13 can remain unchanged as well as the upper part of the engine.
- the shape of the control jacks 30 is designed to fit into the current size of the engine, thus avoiding increasing the center distance of the engine 100.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1913798A FR3104209B1 (en) | 2019-12-05 | 2019-12-05 | hydraulic control system for a variable compression ratio engine |
PCT/FR2020/052280 WO2021111088A1 (en) | 2019-12-05 | 2020-12-04 | Hydraulic control system for a variable compression ratio engine |
Publications (1)
Publication Number | Publication Date |
---|---|
EP4069959A1 true EP4069959A1 (en) | 2022-10-12 |
Family
ID=69743453
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP20841973.9A Withdrawn EP4069959A1 (en) | 2019-12-05 | 2020-12-04 | Hydraulic control system for a variable compression ratio engine |
Country Status (5)
Country | Link |
---|---|
US (1) | US20230018219A1 (en) |
EP (1) | EP4069959A1 (en) |
CN (1) | CN114930006A (en) |
FR (1) | FR3104209B1 (en) |
WO (1) | WO2021111088A1 (en) |
Family Cites Families (17)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0438121B1 (en) * | 1990-01-17 | 1995-04-05 | Mitsubishi Jidosha Kogyo Kabushiki Kaisha | Variable compression ratio apparatus for internal combustion engine |
JP2003322036A (en) * | 2002-05-07 | 2003-11-14 | Nissan Motor Co Ltd | Variable compression ratio mechanism of internal- combustion engine |
FR2914951B1 (en) * | 2007-04-16 | 2012-06-15 | Vianney Rabhi | ELECTROHYDRAULIC DEVICE FOR CLOSED LOOP DRIVING OF THE CONTROL JACK OF A VARIABLE COMPRESSION RATE MOTOR. |
FR2969705B1 (en) * | 2010-12-23 | 2014-04-04 | Vianney Rabhi | TUBULAR VALVE FOR CONTROLLING AN ENGINE WITH VARIABLE VOLUMETRIC RATIO |
WO2013080674A1 (en) | 2011-11-29 | 2013-06-06 | 日産自動車株式会社 | Variable compression ratio internal combustion engine |
JP6283687B2 (en) * | 2012-12-21 | 2018-02-21 | ボーグワーナー インコーポレーテッド | Variable compression ratio piston system |
CN106574550A (en) * | 2014-07-24 | 2017-04-19 | 博格华纳公司 | Single-supply-port activated connecting rod for variable compression ratio engines |
DE102015001066B3 (en) * | 2015-01-29 | 2015-10-22 | Armin Brunner | Hydraulically adjustable connecting rod |
DE102015203417B4 (en) * | 2015-02-26 | 2016-09-15 | Schaeffler Technologies AG & Co. KG | switching valve |
EP3311015B1 (en) * | 2015-06-18 | 2020-02-05 | AVL List GmbH | Longitudinally adjustable connecting rod |
FR3043720B1 (en) * | 2015-11-17 | 2019-11-08 | MCE 5 Development | VARIABLE VOLUMETRIC RATIO ENGINE |
DE102016208209A1 (en) * | 2016-05-12 | 2017-11-16 | Ford Global Technologies, Llc | Hydraulic compression adjustment |
DE102016120950A1 (en) * | 2016-11-03 | 2018-05-03 | Avl List Gmbh | Connecting rod with encapsulated assembly for length adjustment |
DE102017102313B4 (en) * | 2017-02-07 | 2019-01-10 | Hochschule Heilbronn Technik, Wirtschaft, Informatik | Crankshaft of an internal combustion engine |
FR3063518B1 (en) | 2017-03-01 | 2022-01-07 | MCE 5 Development | DEVICE FOR CONTROLLING THE COMPRESSION RATE OF A VARIABLE COMPRESSOR RATIO ENGINE COMPRISING A TWO-WAY SOLENOID VALVE PROVIDED WITH A SECONDARY FLUID RE-BOOSTING CIRCUIT |
DE102017107718A1 (en) * | 2017-04-10 | 2018-10-11 | Avl List Gmbh | Valve mechanism for a length-adjustable connecting rod |
AT521520B1 (en) * | 2018-11-07 | 2020-02-15 | Avl List Gmbh | System and method for adjusting an effective length of a connecting rod and internal combustion engine |
-
2019
- 2019-12-05 FR FR1913798A patent/FR3104209B1/en not_active Expired - Fee Related
-
2020
- 2020-12-04 WO PCT/FR2020/052280 patent/WO2021111088A1/en unknown
- 2020-12-04 EP EP20841973.9A patent/EP4069959A1/en not_active Withdrawn
- 2020-12-04 CN CN202080091997.XA patent/CN114930006A/en active Pending
- 2020-12-04 US US17/756,952 patent/US20230018219A1/en not_active Abandoned
Also Published As
Publication number | Publication date |
---|---|
WO2021111088A1 (en) | 2021-06-10 |
FR3104209A1 (en) | 2021-06-11 |
US20230018219A1 (en) | 2023-01-19 |
FR3104209B1 (en) | 2022-06-03 |
CN114930006A (en) | 2022-08-19 |
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