JP6354477B2 - Vehicle control device - Google Patents

Description

  The present invention relates to a vehicle control device including a torque converter having a lockup mechanism and a variable compression ratio mechanism capable of changing a compression ratio.

  For example, in Patent Literature 1, in the operation region where the lockup clutch is engaged in cooperation with the compression ratio and the lockup mechanism is in the lockup on state, the compression ratio is lowered when the lockup clutch is engaged. Thus, a technique for improving the fuel efficiency of a vehicle by efficiently using the effect of varying the compression ratio is disclosed.

Japanese Patent No. 5146598

  However, in general, the response when the lockup clutch is engaged is better than the response of the variable compression ratio mechanism when changing the compression ratio. Further, as the compression ratio increases, the torque fluctuation of the internal combustion engine during one cycle increases. In other words, in Patent Document 1, the lockup clutch is engaged before the compression ratio is lowered, and there is a risk that a large vehicle vibration may occur due to torque fluctuations of the internal combustion engine.

The vehicle control device of the present invention switches the compression ratio from the high compression ratio to the low compression ratio, and switches the lockup mechanism of the torque converter from the lockup off state to the lockup on state . While controlling the intake valve closing timing of the internal combustion engine away from the bottom dead center until the effective compression ratio of the internal combustion engine taking into account both the response delay and the response delay of the variable valve timing mechanism reaches the target effective compression ratio, When the ignition timing of the internal combustion engine is retarded and the effective compression ratio becomes the target effective compression ratio, the effective compression ratio becomes the target effective compression ratio until the change of the compression ratio by the variable compression ratio mechanism is completed. As described above, by controlling the intake valve closing timing so as to approach the bottom dead center, the torque fluctuation of the internal combustion engine is reduced.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that a big vehicle vibration (buzzing noise) generate | occur | produces due to the torque fluctuation of an internal combustion engine.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the system configuration | structure of the vehicle control apparatus which concerns on this invention. Explanatory drawing which showed typically the schematic structure of the internal combustion engine. Explanatory drawing which showed typically the setting area | region of the compression ratio and the state of a lockup mechanism in an Example. The timing chart which shows an example of the driving | running state in an Example. The flowchart which shows the flow of control in an Example.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram schematically showing a system configuration of a vehicle control device according to the present invention.

  An internal combustion engine 1 mounted on a vehicle (not shown) is connected to an automatic transmission 3 via a torque converter 2 having a lockup mechanism. The torque converter 2 is connected to the output shaft 4 of the internal combustion engine 1. The automatic transmission 3 is connected to the output shaft 5 of the torque converter 2.

  Further, the internal combustion engine 1 has a variable phase timing mechanism 10 that simultaneously delays both the opening timing and closing timing of intake valves (not shown) of each cylinder as the variable valve timing mechanism 10. The phase variable mechanism is already known, for example, in Japanese Patent Application Laid-Open No. 2002-89303 and the like, and a crankshaft 15 which will be described later in terms of the phase of an intake camshaft (not shown) that drives the intake valve to open and close. It is the structure of making it delay with respect to.

  The phase variable mechanism is provided with a sprocket that is rotatable relative to the intake camshaft within a predetermined angle range at one end of the intake camshaft, and the sprocket is connected to a crankshaft 15 described later via a timing chain or a timing belt. It has a linked structure. The valve timing of the intake valve, that is, the phase with respect to the crank angle of the lift central angle of the intake valve is delayed continuously by relatively rotating the intake camshaft and the sprocket using an actuator (not shown) or the like. Thus, the intake valve closing timing is changed.

  The variable valve timing mechanism 10 may be any mechanism that can delay at least the closing timing of the intake valve, and various known variable valve timing mechanisms can be applied.

  The internal combustion engine 1, the torque converter 2 and the automatic transmission 3 are controlled based on a command (signal) from the control unit 6.

  For example, the internal combustion engine 1 is controlled by the control unit 6 so as to obtain an optimum engine torque according to the driving state of the vehicle. The lockup mechanism of the torque converter 2 includes a lockup on state in which a lockup clutch (not shown) is engaged and a state where the internal combustion engine 1 and the automatic transmission 3 are directly connected, and a lockup state in which the lockup clutch is released. It is controlled by the control unit 6 so that the off state can be switched according to the driving state of the vehicle. The automatic transmission 3 is controlled by the control unit 6 so as to obtain an optimum gear position according to the driving state of the vehicle.

  The control unit 6 includes an accelerator opening sensor 7 that detects the opening (depression amount) of an accelerator pedal operated by the driver, and a crank angle sensor 8 that can detect the engine rotational speed together with a crank angle of a crankshaft 15 described later. Signals from various sensors such as an intake cam angle sensor 9 for detecting the phase (conversion angle) of the intake camshaft corresponding to the opening / closing timing of the intake valve are input. The engine load of the internal combustion engine 1 can be detected from the opening degree of the accelerator pedal.

  The control unit 6 can determine whether the lock-up mechanism is in the lock-up on state or the lock-up off state by inputting a signal from the torque converter 2.

  FIG. 2 is an explanatory view schematically showing a schematic configuration of the internal combustion engine 1 described above. In addition to the variable valve timing mechanism 10 described above, the internal combustion engine 1 includes a variable compression ratio mechanism that can change the engine compression ratio by changing the top dead center position of a piston 13 that reciprocates in the cylinder 12 of the cylinder block 11. 14.

  The variable compression ratio mechanism 14 uses a multi-link type piston-crank mechanism in which the piston 13 and the crankpin 16 of the crankshaft 15 are linked by a plurality of links, and is rotatably mounted on the crankpin 16. A lower link 17, an upper link 18 connecting the lower link 17 and the piston 13, a control shaft 19 provided with an eccentric shaft portion 20, and a control link 21 connecting the eccentric shaft portion 20 and the lower link 17. ,have.

  The crankshaft 15 is rotatably supported on the cylinder block 11 by a crank bearing bracket 22.

  One end of the upper link 18 is rotatably attached to the piston pin 23, and the other end is rotatably connected to the lower link 17 by a first connecting pin 24. One end of the control link 21 is rotatably connected to the lower link 17 by the second connecting pin 25, and the other end is rotatably attached to the eccentric shaft portion 20 of the control shaft 19.

  The control shaft 19 is disposed in parallel with the crankshaft 15 and is rotatably supported by the cylinder block 11. Specifically, the control shaft 19 is rotatably supported between the crank bearing bracket 22 and the control bearing bracket 26.

  The control shaft 19 is rotationally driven by an actuator 28 made of an electric motor via a gear mechanism 27, and its rotational position is controlled. The actuator 28 is controlled based on a command from the control unit 6. The control shaft 19 may be rotationally driven by a hydraulic actuator.

  By changing the rotational position of the control shaft 19 by the actuator 28, the position of the eccentric shaft portion 20 that becomes the swing fulcrum of the control link 21 changes. As a result, the posture of the lower link 17 by the control link 21 is changed, and the compression ratio is continuously increased with the piston motion (stroke characteristic) of the piston 13, that is, the change of the top dead center position and the bottom dead center position of the piston 13. Changed to

  In a region where the load of the internal combustion engine 1 is low, the thermal efficiency can be improved and the fuel consumption can be reduced by controlling the compression ratio high. Further, since the knocking is likely to occur in the high load region of the internal combustion engine 1, the compression ratio is controlled to be low.

  Here, when the lock-up mechanism of the torque converter 2 is in the lock-up on state, a so-called booming noise is generated in the passenger compartment due to vibration caused by the torque fluctuation of the internal combustion engine 1. This booming noise increases as the torque fluctuation during one cycle of the internal combustion engine 1 increases. Further, the torque fluctuation during one cycle of the internal combustion engine 1 increases as the compression ratio of the internal combustion engine 1 increases.

  Therefore, when the torque fluctuation during one cycle of the internal combustion engine 1 is large, if the lock-up mechanism of the torque converter 2 is in the lock-up on state, there is a possibility that a loud booming noise may be generated in the vehicle interior.

  Here, the lock-up mechanism of the torque converter 2 has better responsiveness when switching than the responsiveness of the variable compression ratio mechanism 14 when changing the compression ratio.

  Therefore, when the compression ratio of the internal combustion engine 1 is switched from the high compression ratio to the low compression ratio and the lockup mechanism of the torque converter 2 is switched from the lockup off state to the lockup on state, the response of the variable compression ratio mechanism 14 The torque fluctuation of the internal combustion engine 1 is reduced according to the delay.

  As a result, the lockup mechanism of the torque converter 2 does not enter the lockup-on state when the torque fluctuation during one cycle of the internal combustion engine 1 is large, so that the occurrence of vehicle vibration (bumping noise) can be suppressed. it can.

  In the present embodiment, considering the response delay when changing the compression ratio of the variable compression ratio mechanism 14, the compression ratio is switched from the high compression ratio to the low compression ratio, and the lockup mechanism of the torque converter 2 is changed from the lockup off state. When switching to the lock-up on state, the variable valve timing mechanism 10 is controlled so that the intake valve closing timing moves away from the bottom dead center, and the response delay of the variable compression ratio mechanism 14 and the response delay of the variable valve timing mechanism 10 are controlled. The ignition timing of the internal combustion engine 1 is relatively retarded according to the response delay of the effective compression ratio of the internal combustion engine 1 taking both into account. The ignition timing is an ignition timing of an ignition plug (not shown) that ignites an air-fuel mixture in a combustion chamber (not shown) of the internal combustion engine 1, and can be changed with higher responsiveness than the compression ratio.

  In this embodiment, since the intake valve closing timing at the time of high compression ratio is retarded from the bottom dead center, the variable valve timing mechanism 10 is set so that the intake valve closing timing is retarded from the bottom dead center. By controlling, the intake valve closing timing is moved away from the bottom dead center.

  As a result, when the lockup mechanism of the torque converter 2 is switched from the lockup-off state to the lockup-on state, the maximum value of the in-cylinder pressure decreases due to the retard of the ignition timing that is relatively fast in response. Since the torque fluctuation during one cycle is reduced, it is possible to quickly reduce the vehicle vibration (bumping noise) due to the response delay of the compression ratio. Further, since the effective compression ratio of the internal combustion engine 1 is reduced by moving the intake valve closing timing away from the bottom dead center, and the torque fluctuation during one cycle of the internal combustion engine 1 is reduced, the internal combustion engine 1 can be obtained only by retarding the ignition timing. As compared with the case where the torque fluctuation is reduced, it is possible to suppress a decrease in thermal efficiency.

  FIG. 3 is an explanatory diagram schematically showing the compression ratio setting region and the state of the lock-up mechanism of the torque converter 2 in the present embodiment.

  A characteristic line A indicated by a broken line in FIG. 3 is lock-up online. As indicated by an arrow in FIG. 3, when the operating state changes from the region on the left side of the characteristic line A to the region on the right side of the characteristic line A in FIG. 3, the lockup mechanism of the torque converter 2 is in the lockup-off state. To lock-up on status. That is, the high rotation side of the characteristic line A, that is, the region on the right side in FIG. 3 with respect to the characteristic line A is a lock-up on region where the lock-up mechanism of the torque converter 2 is in the lock-up on state. A low rotation side of the characteristic line A, that is, a region on the left side in FIG. 3 with respect to the characteristic line A is a lock-up off region in which the lock-up mechanism of the torque converter 2 is in the lock-up off state. In FIG. 3, as an example in which the operating state changes from the region on the left side of the characteristic line A to the region on the right side of the characteristic line A, when only the engine load decreases, the engine load decreases rapidly and the engine speed It is also conceivable that the engine load decreases slightly, the engine load decreases slightly, and the engine rotation speed increases rapidly. Even when the operation state is in the lock-up on region, the lock-up off state is maintained if the compression ratio is not less than or equal to the allowable compression ratio.

  A characteristic line B indicated by a broken line in FIG. 3 is a lock-up offline located on the lower rotation side than the characteristic line A. When the lock-up mechanism of the torque converter 2 is in the lock-up on state, as indicated by an arrow in FIG. 3, when the operating state changes from the region on the right side of the characteristic line B to the region on the left side of the characteristic line B in FIG. Switch to lock-up off state. That is, the lock-up on state is maintained in the region sandwiched between the characteristic line A and the characteristic line B in FIG. In other words, the region sandwiched between the characteristic line A and the characteristic line B in FIG. 3 is a so-called hysteresis when the lockup mechanism of the torque converter 2 is switched.

  3, the low rotation side of the characteristic line A, that is, the region on the left side in FIG. 3 with respect to the characteristic line A is a high compression ratio operation region in which the compression ratio of the internal combustion engine 1 is set to a predetermined high compression ratio. . In FIG. 3, the high rotation side of the characteristic line A, that is, the region on the right side in FIG. 3 with respect to the characteristic line A is a low compression ratio operation region in which the compression ratio of the internal combustion engine 1 is set to a predetermined low compression ratio. ing.

  When the operation state changes from the low compression ratio operation region to the high compression ratio operation region, the compression ratio is maintained at the low compression ratio in the region sandwiched between the characteristic line A and the characteristic line B in FIG. That is, even if the operating state passes the characteristic line A from the high rotation side to the low rotation side, the compression ratio is maintained at the low compression ratio until the lockup mechanism of the torque converter 2 switches from the lockup on state to the lockup off state. Is done.

  FIG. 3 shows a part of the operation region in which the compression ratio variable control of the internal combustion engine 1 and the lockup mechanism switching control of the torque converter 2 are performed. Regardless of the state of the lockup mechanism, the compression ratio can be set to a low compression ratio in order to avoid knocking or the like. Since the higher the engine speed, the higher the engine speed, the more the noise will be out of the frequency range where the noise (vehicle vibration) is generated. A high compression ratio is also possible.

  FIG. 4 is a timing chart showing an example of an operating state in which the engine rotation speed increases at a substantially constant load and thereafter the engine rotation speed decreases at a substantially constant load. Note that the timing chart shown in FIG. 4 corresponds to an operation state as indicated by an arrow D1 in FIG.

  At time t0, the compression ratio is high and the lockup mechanism of the torque converter 2 is in the lockup off state. At time t1, the operation state enters the low compression ratio operation region and the lockup on region from the high compression ratio operation region and the lockup off region, the compression ratio is switched from the high compression ratio to the low compression ratio, and the torque converter 2 is locked. The up mechanism is switched from the lock-up off state to the lock-up on state.

  Since the change in the compression ratio by the variable compression ratio mechanism 14 causes a response delay with respect to the target value of the effective compression ratio indicated by the broken line, the variable valve timing is set so that the intake valve closing timing moves away from the bottom dead center from time t1. The mechanism 10 is controlled. In this embodiment, since the intake valve closing timing at the time of the high compression ratio is retarded from the bottom dead center, the variable valve timing mechanism 10 is controlled so that the intake valve closing timing is retarded. The intake valve closing timing moves away from the bottom dead center.

  In addition, since the delay of the intake valve closing timing by the variable valve timing mechanism 10 also causes a response delay, the response delay when the compression ratio is changed by the variable compression ratio mechanism 14 and the change of the intake valve closing timing by the variable valve timing mechanism 10 The ignition timing retardation correction is started from time t1 in accordance with the response delay of the effective compression ratio of the internal combustion engine 1 in consideration of the response delay of (retard).

  At time t2, the effective compression ratio reaches the target effective compression ratio, and the ignition timing retardation correction ends. That is, the ignition timing is relatively retarded from time t1 until the effective compression ratio decreases to the target effective compression ratio. From time t2 to time t3, the variable compression ratio mechanism 14 continues to change to a low compression ratio, and the intake valve closing timing is returned to the advance side so that the effective compression ratio becomes substantially constant. At time t3, the change of the compression ratio by the variable compression ratio mechanism 14 is completed, and the retard correction of the intake valve closing timing is completed.

  Time t4 is a timing when the operating state passes the characteristic line B from the high rotation side to the low rotation side. Therefore, at time t4, the lockup mechanism of the torque converter 2 is switched from the lockup on state to the lockup off state, and the compression ratio is switched from the low compression ratio to the high compression ratio. At time t4, since the lockup mechanism of the torque converter 2 is switched to the lockup off state, the intake valve closing timing and the ignition timing are not corrected. At time t5, the compression ratio reaches the high compression ratio.

FIG. 5 is a flowchart showing the control flow of the present embodiment. In S1, the engine speed, the engine load, the state of the lock-up mechanism of the torque converter 2 (whether it is in the lock-up on state or the lock-up off state), the current intake valve closing timing, the current compression ratio, etc. Read various information. In S2, the effective compression ratio is calculated from the current compression ratio and the current intake valve closing timing. In S3, it is determined whether or not the lock-up mechanism of the torque converter 2 is in the lock-up on state. If the lock-up is in the on-state, the process proceeds to S4, and if not, the process proceeds to S9. In S4, the target compression ratio is set to a low compression ratio. In S5, a target effective compression ratio is calculated. Here, the target effective compression ratio is an effective compression ratio at which the vehicle vibration (bumping noise) obtained in advance by experiment or calculation becomes an allowable level. In S6, the current compression ratio is compared with the target compression ratio set in S4. If the current compression ratio is the target compression ratio, the process proceeds to S7, and if the current compression ratio is not the target compression ratio. Proceed to S11. In S7, the retard amount of the intake valve closing timing and the retard amount of the ignition timing are set to zero, and the process proceeds to S8. In S8, the variable compression ratio mechanism 14, the variable valve timing mechanism 10 and the ignition timing are controlled according to the target values.

  In S9, the target compression ratio is set to a high compression ratio. In S10, the retard amount of the intake valve closing timing and the retard amount of the ignition timing are set to zero, and the process proceeds to S8.

  In S11, the retard amount of the intake valve closing timing is calculated from the current compression ratio and the target effective compression ratio. Here, the retard amount of the intake valve closing timing is calculated from the current compression ratio and the target effective compression ratio. Therefore, there is a section in which the retard amount of the intake valve closing timing is increased with a decrease in the compression ratio, such as a section from time t1 to time t2 in FIG. 4, while from time t2 to time t3 in FIG. If the effective compression ratio has decreased to the target effective compression ratio while the compression ratio has not reached the target low compression ratio as in the section, the retard amount of the intake valve closing timing is reduced as the compression ratio decreases. There is also a section that decreases. In S12, the current effective compression ratio is compared with the target effective compression ratio. If the current effective compression ratio is the target effective compression ratio, the process proceeds to S13, and the current effective compression ratio is the target effective compression ratio. If not, the process proceeds to S14. In S13, the retard amount of the ignition timing is set to zero and the process proceeds to S8. In S14, the retard amount of the ignition timing is calculated from the current effective compression ratio and the target effective compression ratio, and the process proceeds to S8.

  In the above-described embodiment, the ignition timing is retarded and the intake valve closing timing is kept away from the bottom dead center in order to reduce torque fluctuation during one cycle of the internal combustion engine 1, but the ignition timing is delayed. It may be possible to perform only turning or only keeping the intake valve closing timing away from the bottom dead center.

  Even if the torque fluctuation in one cycle of the internal combustion engine 1 is reduced only by retarding the ignition timing, the vehicle vibration (bumping noise) due to the response delay of the compression ratio can be quickly reduced.

  Moreover, even if the torque fluctuation during one cycle of the internal combustion engine 1 is reduced only by moving the intake valve closing timing away from the bottom dead center, the torque fluctuation during one cycle of the internal combustion engine 1 is reduced only by retarding the ignition timing. It is possible to suppress a decrease in thermal efficiency as compared with the case where it is made to occur.

DESCRIPTION OF SYMBOLS 1 ... Internal combustion engine 2 ... Torque converter 3 ... Automatic transmission 10 ... Variable valve timing mechanism 14 ... Variable compression ratio mechanism

Claims (1)

A variable compression ratio mechanism capable of changing the compression ratio of the internal combustion engine;
A variable valve timing mechanism capable of changing the intake valve closing timing of the internal combustion engine;
In a vehicle control device having a lock-up mechanism and a torque converter disposed between the internal combustion engine and the transmission,
When switching the compression ratio from the high compression ratio to the low compression ratio and switching the lockup mechanism from the lockup off state to the lockup on state,
The intake valve closing timing of the internal combustion engine is set to the bottom dead center until the effective compression ratio of the internal combustion engine taking into account both the response delay of the variable compression ratio mechanism and the response delay of the variable valve timing mechanism becomes the target effective compression ratio. And the ignition timing of the internal combustion engine is retarded,
When the effective compression ratio becomes the target effective compression ratio, the intake valve closing timing is set at the bottom dead center so that the effective compression ratio becomes the target effective compression ratio until the change of the compression ratio by the variable compression ratio mechanism is completed. A control apparatus for a vehicle, wherein the torque fluctuations of the internal combustion engine are reduced by controlling to approach .

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