Vehicle control device

Abstract

To provide a vehicle control device suppressed in increase of vehicle vibration.SOLUTION: A vehicle control device includes: a transmission to which power of a supercharger-attached engine installed on a front side and an engine installed on a rear side is transmitted via a propeller shaft; and a waste gate valve opening / closing an exhaust bypass passage connected to an exhaust passage while bypassing a turbine of a super charger. The control device includes: an acquisition part acquiring an engine speed and a target supercharging pressure; a prediction part predicting that vehicle vibration increases when the engine speed is a prescribed speed or lower and the target supercharging pressure is a prescribed pressure or higher, and predicting that the vibration of the vehicle does not increase when the engine speed is higher than the prescribed engine speed or the target supercharging pressure is lower than the prescribed pressure; and a smooth change control part executing a smooth change processing smoothly raising an actual supercharging pressure to the target supercharging pressure.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] BACKGROUND ART An engine equipped with a supercharger is known (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-205306 Summary of the Invention [Problem to be solved by the invention]

[0004] When a supercharged engine is installed in a vehicle, depending on the vehicle's structure, there is a risk that the vibration of the vehicle will increase due to an increase in supercharging pressure when the engine speed is low.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a vehicle control device that suppresses an increase in vehicle vibration. [Means for solving the problem]

[0006] The object of the present invention is to provide a control device for a vehicle having a supercharged engine mounted on the front side, a transmission mounted on the rear side to which power from the engine is transmitted via a propeller shaft, and a wastegate valve for opening and closing an exhaust bypass passage that bypasses the turbine of the supercharger and is connected to an exhaust passage of the engine, the control device including an acquisition unit that acquires an engine speed and a target supercharging pressure when there is a request for acceleration, and a control unit that, when the engine speed is equal to or lower than a predetermined speed and the target supercharging pressure is equal to or higher than a predetermined pressure, acquires a target supercharging pressure and, when the engine speed is equal to or lower than a predetermined speed and the target supercharging pressure is equal to or higher than a predetermined pressure, This can be achieved by a vehicle control device that includes: a prediction unit that predicts that vibration of the vehicle will increase, and, when the engine speed is higher than the predetermined speed or the target boost pressure is less than the predetermined pressure, predicts that vibration of the vehicle will not increase when the actual boost pressure rises to the target boost pressure at the engine speed; and a gradual change control unit that, when it is predicted that vibration of the vehicle will increase, executes gradual change processing to gradually increase the actual boost pressure to the target boost pressure by gradually reducing the opening of the wastegate valve more slowly than when it is predicted that vibration of the vehicle will not increase.

[0007] The above object is also to provide a control device for a vehicle having a supercharged engine mounted on the front side, a transmission mounted on the rear side to which power from the engine is transmitted via a propeller shaft, and an air bypass valve that opens and closes an intake bypass passage that bypasses a compressor of the supercharger and is connected to an intake passage of the engine, the control device including an acquisition unit that acquires an engine speed and a target supercharging pressure when there is a request for acceleration, and a control unit that acquires an engine speed and a target supercharging pressure when the engine speed is equal to or lower than a predetermined speed and the target supercharging pressure is equal to or higher than a predetermined pressure, and This can also be achieved by a vehicle control device including: a prediction unit that predicts that vibration of the vehicle will increase when the engine speed is higher than the predetermined speed or the target boost pressure is less than the predetermined pressure, and that predicts that vibration of the vehicle will not increase when the actual boost pressure increases to the target boost pressure at that engine speed; and a gradual change control unit that, when it is predicted that vibration of the vehicle will increase, executes gradual change processing to gradually increase the actual boost pressure to the target boost pressure by reducing the opening of the air bypass valve more gradually than when it is predicted that vibration of the vehicle will not increase. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a vehicle control device that suppresses an increase in vehicle vibration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a vehicle. [Figure 2] FIG. 2 is a schematic diagram of the engine. [Figure 3] FIG. 3A is a graph showing the magnitude of vehicle vibration when there is an acceleration request and the target boost pressure is equal to or higher than a predetermined pressure P, and FIG. 3B is a flowchart showing an example of control executed by the ECU. [Figure 4] FIG. 4 is a timing chart illustrating the slow-change processing. [Figure 5] FIG. 5 is a timing chart illustrating the slow-change processing in the modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] FIG. 1 is a schematic diagram of a vehicle 1. The vehicle 1 includes an engine 10, a propeller shaft 40, a transmission 50, a drive shaft 60, drive wheels 70, and an ECU (Electronic Control Unit) 100. The engine 10 is a power source for driving the vehicle 1. The engine 10 is a gasoline engine, but is not limited thereto and may be, for example, a diesel engine or a hydrogen fuel engine. The propeller shaft 40 extends in the longitudinal direction of the vehicle 1 and connects the engine 10 to the transmission 50. The propeller shaft 40 may be provided with a torque tube, which is a cover member that covers the periphery of the propeller shaft 40. The rotational power of the engine 10 is transmitted to the transmission 50 via the propeller shaft 40. The transmission 50 transmits the rotational power of the propeller shaft 40 to the drive shaft 60. The transmission 50 is a gearbox that reduces the rotation of the propeller shaft 40 at a predetermined reduction ratio before transmitting it to the drive shaft 60. The rotation of the drive shaft 60 rotates the drive wheels 70.

[0011] The engine 10 is mounted in an engine compartment on the front side of the vehicle 1. The transmission 50 is mounted on the rear side of the vehicle 1, for example, on the rear side of the passenger compartment. The vehicle 1 is a so-called FR vehicle. Therefore, the drive wheels 70 are rear wheels. The engine 10 and the transmission 50 are controlled by an ECU 100.

[0012] FIG. 2 is a schematic diagram of an engine 10. The engine 10 has a cylinder block with multiple cylinders 11 (only one is shown in FIG. 2). Pistons 12 provided in the cylinders 11 are connected to crankshafts 13 via connecting rods 14. The connecting rods 14 convert the reciprocating motion of the pistons 12 into the rotational motion of the crankshaft 13. A cylinder head is attached to the top of the cylinder block. A combustion chamber 15 in which an ignition plug 16 is disposed is formed between the cylinder head and the upper end of the piston 12. An intake port 17 and an exhaust port 18 provided corresponding to the combustion chamber 15 are connected to an intake passage 19 and an exhaust passage 20, respectively.

[0013] A compressor 23A of the turbocharger 23 is disposed in the intake passage 19. A turbine 23B of the turbocharger 23 is disposed in the exhaust passage 20. Exhaust gas generated by combustion in the combustion chamber 15 of each cylinder is introduced into the turbine 23B of the turbocharger 23 through the exhaust manifold. When the introduced exhaust gas operates the turbine 23B, the compressor 23A on the intake passage 19 side operates in conjunction, compressing the air on the intake passage 19 side. As the air is compressed, the pressure inside the intake passage 19, i.e., the intake pressure, is increased, and this pressure efficiently fills the combustion chamber 15 with air.

[0014] The intake passage 19 is provided with, from upstream to downstream, an air flow meter 92, an intake bypass passage 33, a boost pressure sensor 94, a throttle valve 22, and a throttle opening sensor 93. The intake bypass passage 33 bypasses the compressor 23A. The intake bypass passage 33 is provided with an air bypass valve 34. The throttle valve 22 adjusts the intake air amount by changing its opening. The intake passage 19 branches at an intake manifold provided downstream of the throttle valve 22 in the intake direction, and is connected to each combustion chamber 15 through these branched portions. An in-cylinder injection valve 25 that injects fuel into the cylinder 11 is provided therein. The air flow meter 92, throttle opening sensor 93, and boost pressure sensor 94 will be described later.

[0015] An exhaust bypass passage 35 that bypasses the turbine 23B is provided in the exhaust passage 20. A wastegate valve 36 is provided in the exhaust bypass passage 35. The wastegate valve 36 adjusts the boost pressure of the turbocharger 23. A catalyst 29 that purifies the exhaust gas is provided downstream of the wastegate valve 36.

[0016] The engine 10 is equipped with an intake valve 26 and an exhaust valve 27 that respectively open and close an intake port 17 and an exhaust port 18 that are connected to an intake passage 19 and an exhaust passage 20. The intake valve 26 and the exhaust valve 27 open and close in accordance with the rotation of an intake-side camshaft and an exhaust-side camshaft that are drivingly connected to the crankshaft 13. As a result, the intake valve 26 and the exhaust valve 27 are driven to open and close in synchronization with the rotation of the crankshaft 13, that is, at predetermined timing corresponding to the reciprocating movement of each piston 12.

[0017] The intake variable valve mechanism 26a changes the opening and closing timing of the intake valve 26 by changing the rotation phase of the intake camshaft relative to the crankshaft 13. The exhaust variable valve mechanism 27a changes the opening and closing timing of the exhaust valve 27 by changing the rotation phase of the exhaust camshaft relative to the crankshaft 13. This makes it possible to change the valve overlap period, which is the period during which both the intake valve 26 and the exhaust valve 27 are open. The intake variable valve mechanism 26a and the exhaust variable valve mechanism 27a are hydraulic, but are not limited to this.

[0018] The ECU 100 includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a storage device. The ECU 100 controls the engine 10 by executing programs stored in the ROM or the storage device. The ECU 100 is an example of a control device for the vehicle 1. The ECU 100 functionally realizes an acquisition unit, a prediction unit, and a slow-change control unit using the CPU, ROM, RAM, and storage device. The ECU 100 controls the fuel injection amount, ignition timing, opening degree of the throttle valve 22, opening and closing timings of the intake valve 26 and the exhaust valve 27, opening degrees of the air bypass valve 34 and the wastegate valve 36, etc., according to the operating state of the engine 10.

[0019] The ECU 100 performs predetermined calculations based on detection signals from the various sensors described above. For example, the ECU 100 calculates the engine speed based on the detection signal from the crank angle sensor 90. The ECU 100 calculates the opening degree of the accelerator pedal operated by the driver based on the detection signal from the accelerator opening sensor 91. The ECU 100 calculates the intake air amount, which is the amount of air introduced into the combustion chamber 15, based on the detection signal from the air flow meter 92. The ECU 100 calculates the opening degree of the throttle valve 22 based on the detection signal from the throttle opening sensor 93. The ECU 100 calculates the actual boost pressure, which is the pressure of the intake air supercharged by the compressor 23A, based on the detection signal from the boost pressure sensor 94.

[0020] FIG. 3A is a graph showing the magnitude of vibration of the vehicle 1 when there is an acceleration request and the target boost pressure is equal to or higher than a predetermined pressure P. FIG. 3A shows the magnitude of vibration of the vehicle 1 when there is an acceleration request when the engine speed is low, and the actual boost pressure is increased to the target boost pressure, causing the engine speed to increase. The horizontal axis represents the engine speed, and the vertical axis represents the magnitude of vibration of the vehicle 1. FIG. 3A shows a comparative example indicated by a dotted line and this embodiment indicated by a solid line. The comparative example shows a case where the actual boost pressure is increased to the target boost pressure when the engine speed is less than a predetermined speed R. This embodiment shows a case where the actual boost pressure is increased to the target boost pressure more slowly than in the comparative example, when the engine speed is less than the predetermined speed R.

[0021] In the comparative example, vibration increases when the engine speed is below a predetermined speed R. When the engine speed is low, the actual boost pressure rises to the target boost pressure, increasing the engine torque. Here, the transmission 50 resonates when the engine speed is low. In the comparative example, the engine torque is high when such resonance occurs, increasing the vibration of the vehicle 1. In this embodiment, as will be described in detail later, when the engine speed is below the predetermined speed R and the target boost pressure is equal to or higher than a predetermined pressure P, a gradual change process is executed to increase the actual boost pressure to the target boost pressure more slowly than in the comparative example. As a result, in this embodiment, the engine torque is maintained low when the engine speed is low. This suppresses an increase in vibration of the vehicle 1.

[0022] FIG. 3B is a flowchart illustrating control executed by ECU 100. ECU 100 determines whether or not there is an acceleration request (step S1). If the answer is No in step S1, this control ends. If the answer is Yes in step S1, ECU 100 acquires the engine speed and target boost pressure (step S2). The engine speed is calculated by ECU 100 based on the detection signal of crank angle sensor 90. The target boost pressure is calculated by ECU 100 according to the operating state of engine 10 and the throttle opening. Step S2 is an example of processing executed by the acquisition unit.

[0023] Next, ECU 100 predicts whether vibration of vehicle 1 will increase based on the engine speed and the target boost pressure (step S3). Specifically, if the engine speed is equal to or lower than a predetermined speed R and the target boost pressure is equal to or higher than a predetermined pressure P, it is predicted that vibration of vehicle 1 will increase if the actual boost pressure rises to the target boost pressure at the engine speed acquired in step S2. If the engine speed is higher than the predetermined speed R or the target boost pressure is lower than the predetermined pressure P, it is predicted that vibration of vehicle 1 will not increase even if the actual boost pressure rises to the target boost pressure at the engine speed acquired in step S2. Step S3 is an example of processing executed by the prediction unit. Note that the predetermined speed R is higher than the idle speed, and the predetermined pressure P is higher than the boost pressure in an idle operating state.

[0024] If the answer to step S3 is No, that is, if it is predicted that the vibration of the vehicle 1 will not increase, this control ends. In this case, for example, the ECU 100 immediately reduces the opening of the wastegate valve 36 so that the actual boost pressure becomes the target boost pressure. This increases the flow rate of exhaust gas passing through the turbine 23B, and the actual boost pressure quickly rises to the target boost pressure. This ensures acceleration responsiveness.

[0025] If the answer to step S3 is Yes, that is, if it is predicted that the vibration of the vehicle 1 will increase, the ECU 100 executes a gradual change process (step S4). The gradual change process is a process that increases the actual boost pressure to the target boost pressure more slowly than when it is predicted that the vibration of the vehicle 1 will not increase. In this embodiment, the gradual change process is executed by reducing the opening of the wastegate valve 36 more slowly than when it is predicted that the vibration of the vehicle 1 will not increase. "Reducing the opening slowly" means slowing the rate at which the opening is reduced. In other words, by executing the gradual change process, the boost delay is increased more than when it is predicted that the vibration of the vehicle 1 will not increase. Step S4 is an example of a process executed by the gradual change control unit.

[0026] Fig. 4 is a timing chart illustrating the change-reduction processing. Fig. 4 shows the transitions of the engine speed, the magnitude of vibration of the vehicle 1, the boost pressure, the engine torque, and the opening of the wastegate valve 36. Fig. 4 shows a comparative example indicated by a dotted line and this embodiment indicated by a solid line. In the comparative example, the change-reduction processing is not executed. In this embodiment, the change-reduction processing is executed.

[0027] In the comparative example, when an acceleration request is made (time t0), the opening of the wastegate valve 36 immediately decreases, the actual boost pressure increases to the target boost pressure, and the engine torque increases to the target torque (time t1). Here, the engine speed is less than the predetermined speed R, and the actual boost pressure is equal to or greater than the predetermined pressure P, so vibration of the vehicle 1 increases.

[0028] In this embodiment, when an acceleration request is made (time t0), the opening of the wastegate valve 36 gradually decreases, the actual boost pressure gradually increases, and the engine torque also gradually increases. When the engine speed exceeds a predetermined speed R (time t2), the actual boost pressure increases to near the target boost pressure, and the engine torque also increases to near the target torque. In this way, in this embodiment, the actual boost pressure increases to the target boost pressure more gradually than in the comparative example. This suppresses an increase in vibration of the vehicle 1. Note that the opening of the air bypass valve 34 is maintained constant while the slow-change processing is being executed.

[0029] [Variations] Next, a modified example of the gradual change processing will be described. In this modified example, the gradual change processing is executed by gradually decreasing the opening of the air bypass valve 34 more than when it is predicted that the vibration of the vehicle 1 will not increase. This allows the flow rate of intake air passing through the compressor 23A to gradually increase, and the actual boost pressure to gradually increase to the target boost pressure.

[0030] FIG. 5 is a timing chart illustrating the gradual change processing in the modified example. When an acceleration request is made (time t0), the opening of the air bypass valve 34 gradually decreases, the actual boost pressure gradually increases, and the engine torque also gradually increases. When the engine speed exceeds a predetermined speed R (time t2), the actual boost pressure increases to near the target boost pressure, and the engine torque also increases to near the target torque. In this way, in this modified example, the actual boost pressure increases to the target boost pressure more gradually than in the comparative example. This suppresses an increase in vibration of the vehicle 1. Note that the opening of the wastegate valve 36 is maintained constant during execution of the gradual change processing in the modified example.

[0031] The gradual change process may be executed by gradually reducing the opening degrees of the air bypass valve 34 and the wastegate valve 36 more gradually than when it is predicted that the vibration of the vehicle 1 will not increase.

[0032] In addition, the ECU 100 may control the intake variable valve mechanism 26a and the exhaust variable valve mechanism 27a to perform a gradual change process by gradually extending the valve overlap period more than if it were predicted that the vibration of the vehicle 1 would not increase.

[0033] Furthermore, the shape, number and size of the blades of the turbine 23B may be changed so that the turbine efficiency decreases and the actual supercharging pressure becomes less than the predetermined pressure P when the engine speed is equal to or less than the predetermined speed R.

[0034] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0035] 1 vehicle 10 Engine 19 Intake passage 20 Exhaust passage 23 Turbocharger 23A Compressor 23B Turbine 33 Intake bypass passage 34 Air bypass valve 35 Exhaust bypass passage 36 Wastegate valve 100 ECU (controller, acquisition unit, prediction unit, slow change control unit)

Claims

1. A supercharged engine mounted on the front side, a transmission mounted on the rear side and to which power from the engine is transmitted via a propeller shaft; a wastegate valve that opens and closes an exhaust bypass passage that bypasses the turbine of the turbocharger and is connected to an exhaust passage of the engine; A vehicle control device having an acquisition unit that acquires an engine rotation speed and a target boost pressure when there is an acceleration request; a prediction unit that predicts that vibration of the vehicle will increase if the actual boost pressure rises to the target boost pressure at the engine speed, when the engine speed is equal to or lower than a predetermined speed and the target boost pressure is equal to or higher than a predetermined pressure, and that predicts that vibration of the vehicle will not increase if the actual boost pressure rises to the target boost pressure at the engine speed, when the engine speed is higher than the predetermined speed or the target boost pressure is lower than the predetermined pressure; a gradual change control unit that executes a gradual change process in which, when it is predicted that vibration of the vehicle will increase, the opening degree of the wastegate valve is reduced more gradually than when it is predicted that vibration of the vehicle will not increase, thereby gradually increasing the actual boost pressure to the target boost pressure; A vehicle control device comprising:

2. A supercharged engine mounted on the front side, a transmission mounted on the rear side and to which power from the engine is transmitted via a propeller shaft; an air bypass valve that opens and closes an intake bypass passage that bypasses the compressor of the turbocharger and is connected to an intake passage of the engine; A vehicle control device having an acquisition unit that acquires an engine rotation speed and a target boost pressure when there is an acceleration request; a prediction unit that predicts that vibration of the vehicle will increase if the actual boost pressure rises to the target boost pressure at the engine speed, when the engine speed is equal to or lower than a predetermined speed and the target boost pressure is equal to or higher than a predetermined pressure, and that predicts that vibration of the vehicle will not increase if the actual boost pressure rises to the target boost pressure at the engine speed, when the engine speed is higher than the predetermined speed or the target boost pressure is lower than the predetermined pressure; a gradual change control unit that executes a gradual change process in which, when it is predicted that vibration of the vehicle will increase, the opening of the air bypass valve is reduced more gradually than when it is predicted that vibration of the vehicle will not increase, thereby gradually increasing the actual boost pressure to the target boost pressure; A vehicle control device comprising:

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