Vehicle control device

Abstract

To prevent reverse rotation of a crank shaft caused by reduction of engine speed.SOLUTION: A vehicle comprises: an internal combustion engine with a crank shaft; a motor generator with an output shaft; a clutch which is switchable between an engagement state and an open state; a first rotation sensor which can detect an engine revolution number; a second rotation sensor which can detect a MG revolution number; and a control device. When the clutch is in the engagement state at the time of driving the internal combustion engine, the engine revolution number is a prescribed revolution number defined in advance or less which is lower than idle rotation number, and absolute number of a difference between the engine revolution number and the MG revolution number is a difference rotation number defined in advance or less, the control device changes the clutch to be in the open state, and stops fuel injection and ignition of the internal combustion engine.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] The vehicle described in Patent Document 1 includes an internal combustion engine, a motor generator, a clutch, and a control device. The internal combustion engine and the motor generator are driving sources of the vehicle. The internal combustion engine includes a crankshaft. The motor generator includes an output shaft. Further, the clutch is interposed between the crankshaft of the internal combustion engine and the output shaft of the motor generator. Further, the control device can control the engaged state and the released state of the clutch. When the clutch is in the engaged state, the torque of the internal combustion engine can be transmitted to the output shaft of the motor generator. On the other hand, when the clutch is in the released state, the torque of the internal combustion engine is not transmitted to the output shaft of the motor generator.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the vehicle described in Patent Document 1, the engine speed of the internal combustion engine may decrease when the clutch is in the engaged state. When the engine speed decreases to near zero, the force that the piston moves toward the top dead center cannot resist the pressure of the gas compressed in the compression stroke. At this time, the piston cannot overcome the compression top dead center and is pushed back toward the bottom dead center. That is, the crankshaft of the internal combustion engine rotates slightly in the reverse direction. When ignition is performed in the cylinder and unburned fuel remains in the cylinder while the crankshaft is rotating in the reverse direction, the crankshaft rotates greatly in the reverse direction due to the combustion of the fuel.

Means for Solving the Problems

[0005] In order to solve the above problems, the present invention is applied to a vehicle including an internal combustion engine having a crankshaft, a motor generator having an output shaft that is part of a driving force transmission path from the crankshaft to a driving wheel, a clutch interposed between the crankshaft and the output shaft, a first rotation sensor capable of detecting an engine rotation speed that is the rotation speed of the crankshaft, and a second rotation sensor capable of detecting an MG rotation speed that is the rotation speed of the motor generator. The clutch is switchable between an engaged state in which torque can be transmitted between the crankshaft and the output shaft and a released state in which torque cannot be transmitted between the crankshaft and the output shaft. The control device controls the internal combustion engine and the clutch. During driving of the internal combustion engine, when the clutch is in the engaged state, the engine rotation speed is equal to or lower than a specified rotation speed that is set in advance to be lower than the idle rotation speed, and the absolute value of the difference between the engine rotation speed and the MG rotation speed is equal to or lower than a specified differential rotation speed, the clutch is changed to the released state and fuel injection and ignition in the internal combustion engine are stopped.

[0006] According to the above configuration, when the clutch is in the engaged state and there is a possibility that the piston cannot overcome the compression top dead center, the driving of the internal combustion engine is stopped. That is, when a situation may occur in which the crankshaft rotates slightly in the reverse direction, the driving of the internal combustion engine is stopped before such a phenomenon can occur. Therefore, a situation in which fuel burns while the crankshaft is rotating slightly in the reverse direction is unlikely to occur. Further, the clutch is changed to the released state in accordance with the stop of the driving of the internal combustion engine. Therefore, the torque of the motor generator is not used to idle the internal combustion engine.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Embodiment for Carrying Out the Invention

[0008] Hereinafter, an embodiment of a vehicle control device will be described with reference to the drawings. [Configuration of Vehicle Drive System] As shown in FIG. 1, the vehicle 500 includes an internal combustion engine 10, a transmission unit 20, left and right drive wheels 30, and a differential 40. The internal combustion engine 10 is a drive source for traveling. The internal combustion engine 10 has a crankshaft 11 as an output shaft.

[0009] The transmission unit 20 is on the power transmission path from the internal combustion engine 10 to each drive wheel 30. The transmission unit 20 includes a motor generator 21, a clutch 22, a torque converter 23, an automatic transmission 24, an oil pump 25, and a hydraulic unit 26.

[0010] The motor generator 21 has a stator and a rotor. The rotor rotates relative to the stator. The motor generator 21 is a so-called three-phase AC motor. The motor generator 21 has an output shaft 21A. The output shaft 21A rotates integrally with the rotor. The output shaft 21A is connected to the crankshaft 11 via the clutch 22. That is, the output shaft 21A is a part of the drive force transmission path from the crankshaft 11 to the drive wheels 30.

[0011] The motor generator 21 is connected to a battery 21C of the vehicle 500 via an inverter 21B of the vehicle 500. The motor generator 21 functions as an electric motor and a generator. When the motor generator 21 functions as an electric motor, it can apply torque to the crankshaft 11 with electric power from the battery 21C. Also, when the motor generator 21 functions as a generator, it supplies electric power to the battery 21C.

[0012] The clutch 22 is interposed between the crankshaft 11 and the output shaft 21A of the motor generator 21. The clutch 22 can be switched between an engaged state and a released state by hydraulic pressure. When the clutch 22 is in the engaged state, torque transmission is possible between the crankshaft 11 and the output shaft 21A. When the clutch 22 is in the released state, torque transmission is impossible between the crankshaft 11 and the output shaft 21A.

[0013] The torque converter 23 has a lock-up clutch 23A, an input shaft 23B, and an output shaft 23C. The input shaft 23B is connected to the opposite side of the clutch 22 on the output shaft 21A of the motor generator 21. The lock-up clutch 23A is interposed between the input shaft 23B and the output shaft 23C. The lock-up clutch 23A can be switched between an engaged state and a released state by hydraulic pressure. When the lock-up clutch 23A is in the engaged state, the input shaft 23B and the output shaft 23C rotate integrally. When the lock-up clutch 23A is in the engaged state, the torque converter 23 shifts the torque input to the input shaft 23B and outputs it from the output shaft 23C.

[0014] The automatic transmission 24 is connected to the output shaft 23C of the torque converter 23. That is, the automatic transmission 24 is connected to the crankshaft 11 via the torque converter 23. The automatic transmission 24 has a plurality of gear mechanisms and a plurality of engagement elements, although not shown in the figure. The engagement elements of the automatic transmission 24 are, for example, a clutch mechanism and a brake mechanism. Each engagement element of the automatic transmission 24 can be switched between an engaged state and a released state by hydraulic pressure. By switching the engaged state and the released state of each engagement element, the automatic transmission 24 can switch the gear stage.

[0015] The oil pump 25 is an electric pump. The hydraulic pressure generated by the oil pump 25 is supplied to the transmission unit 20. Specifically, the hydraulic pressure generated by the oil pump 25 is supplied to the clutch 22, the torque converter 23, the lock-up clutch 23A, and the automatic transmission 24.

[0016] The hydraulic unit 26 includes the hydraulic circuits of the clutch 22, torque converter 23, lock-up clutch 23A, and automatic transmission 24, and various hydraulic control valves for controlling the hydraulic pressure of these components. By controlling the hydraulic unit 26, for example, the engaged and released states of the clutch 22 are switched. Note that in FIG. 1, the illustration of the hydraulic circuit and hydraulic control valves of the hydraulic unit 26 is omitted.

[0017] The differential 40 is connected to the automatic transmission 24 and each drive wheel 30. That is, the differential 40 is interposed between the transmission unit 20 and each drive wheel 30. The differential 40 distributes the torque output from the transmission unit 20 to the left and right drive wheels 30. The differential 40 allows a difference in rotational speed to occur between the left and right drive wheels 30.

[0018] The vehicle 500 includes a first rotation sensor 51 and a second rotation sensor 52. The first rotation sensor 51 is located near the crankshaft 11. The first rotation sensor 51 detects the angular position of the crankshaft 11 as the crank angle CA. The second rotation sensor 52 is attached to the stator of the motor generator 21. The second rotation sensor 52 detects the angular position of the output shaft 21A of the motor generator 21 as the motor angle MA.

[0019] [Regarding the control device] The vehicle 500 includes a control device 100. The control device 100 acquires a signal related to the crank angle CA output by the first rotation sensor 51. Further, the control device 100 calculates the engine rotational speed NE, which is the number of rotations of the crankshaft 11 per unit time, based on the signal related to the crank angle CA. The control device 100 acquires a signal related to the motor angle MA output by the second rotation sensor 52. Further, the control device 100 calculates the MG rotational speed NM1, which is the number of rotations of the output shaft 21A per unit time, based on the signal related to the motor angle MA. Note that if the clutch 22 is in the engaged state, the values of the engine rotational speed NE and the MG rotational speed NM1 substantially coincide.

[0020] The control device 100 controls the internal combustion engine 10. The control device 100 controls fuel injection and ignition in the internal combustion engine 10. That is, the control device 100 controls the driving and stopping of the internal combustion engine 10.

[0021] Further, the control device 100 controls the clutch 22. Specifically, the control device 100 switches the engaged state and the released state of the clutch 22 by controlling the hydraulic pressure unit 26. Note that the control device 100 can switch the gear position of the automatic transmission 24 and the engaged state and the released state of the lock-up clutch 23A by controlling the hydraulic pressure unit 26.

[0022] [Engine Stop Control Executed by the Control Device] Hereinafter, the engine stop control executed by the control device 100 will be described. The control device 100 repeatedly executes the engine stop control while the internal combustion engine 10 is running.

[0023] As shown in FIG. 2, when the control device 100 executes the engine stop control, first, the process of step S11 is executed. In step S11, the control device 100 determines whether the clutch 22 is in the engaged state. If the clutch 22 is in the released state (S11: NO), the control device 100 ends the engine stop control. On the other hand, if the clutch 22 is in the engaged state (S11: YES), the process of the control device 100 proceeds to step S12.

[0024] In step S12, the control device 100 calculates the engine speed NE based on the detection value of the first rotation sensor 51. Then, the control device 100 determines whether the engine speed NE is equal to or less than the specified rotation speed RR. The specified rotation speed RR is a minimum rotation speed at which the internal combustion engine 10 can continue to drive independently, that is, a rotation speed smaller than the idle speed. An example of the specified rotation speed RR is 250 rpm. If a negative determination is made in step S12 (S12: NO), the control device 100 ends the engine stop control. On the other hand, if an affirmative determination is made in step S12 (S12: YES), the process of the control device 100 proceeds to step S13.

[0025] In step S13, the control device 100 calculates the MG rotation speed NM1 based on the detection value of the second rotation sensor 52. Then, the control device 100 determines whether the absolute value of the difference between the engine rotation speed NE and the MG rotation speed NM1 is less than or equal to the differential rotation speed DR. The differential rotation speed DR is the maximum value of the rotation speed that can be considered when the rotation speed of the crankshaft 11 and the rotation speed of the motor generator 21 are interlocked. An example of the differential rotation speed DR is 100 rpm. If a negative determination is made in step S13 (S13: NO), the control device 100 ends the engine stop control. On the other hand, if an affirmative determination is made in step S13 (S13: YES), the process of the control device 100 proceeds to step S14.

[0026] In step S14, the control device 100 controls the hydraulic pressure unit 26 to change the clutch 22 from the engaged state to the released state. After that, the process of the control device 100 proceeds to step S15.

[0027] In step S15, the control device 100 stops fuel injection and ignition in the internal combustion engine 10. That is, the control device 100 stops driving the internal combustion engine 10. Then, the control device 100 ends the engine stop control.

[0028] [Operation of the present embodiment] During the running of the vehicle 500, the driving wheels 30 may be subjected to a resistance that stops their rotation due to the influence of the road surface or the like. The resistance received by the driving wheels 30 is transmitted to the power transmission path. Therefore, when the clutch 22 is in the engaged state, if a resistance that stops the rotation of the driving wheels 30 acts, the rotational speed of the crankshaft 11 decreases. That is, the engine speed NE decreases. If the engine speed NE becomes smaller than or equal to the specified speed RR, the force that moves the piston of the internal combustion engine 10 toward the top dead center may not be able to resist the pressure of the gas compressed during the compression stroke. At this time, the piston cannot overcome the compression top dead center and is pushed back toward the bottom dead center. That is, the crankshaft 11 of the internal combustion engine 10 rotates slightly in the reverse direction. Even in such a state, if the driving of the internal combustion engine 10 continues, fuel injection and ignition continue in the internal combustion engine 10. If fuel injection and ignition are executed in the internal combustion engine 10 while the crankshaft 11 is rotating in the reverse direction, the crankshaft 11 will rotate greatly in the reverse direction due to the combustion of the fuel.

[0029] [Effects of the Present Embodiment] (1) According to the above embodiment, when the clutch 22 is in the engaged state and the engine speed NE is less than or equal to the specified speed RR, the driving of the internal combustion engine 10 is stopped. The situation where the engine speed NE is less than or equal to the specified speed RR is a situation in which, in the near future, a phenomenon may occur in which the piston cannot overcome the compression top dead center and is pushed back toward the bottom dead center. In other words, the situation where the engine speed NE is less than or equal to the specified speed RR is the situation immediately before the engine speed NE becomes zero. That is, in the above embodiment, the driving of the internal combustion engine 10 is stopped before the phenomenon of the piston being pushed back toward the bottom dead center occurs. Therefore, a situation where fuel burns while the crankshaft 11 is rotating slightly in the reverse direction is less likely to occur. Also, in accordance with the stop of the driving of the internal combustion engine 10, the clutch 22 is changed to the released state. Therefore, the torque of the motor generator 21 is not used to rotate the internal combustion engine 10 idly.

[0030] (2) Even though the clutch 22 is in the engaged state, if the difference between the engine speed NE and the MG speed NM1 is greater than the differential rotation speed DR, there may be an abnormality in the detection of the crank angle CA. That is, there may be a problem with the first rotation sensor 51. In the above embodiment, when the absolute value of the difference between the engine speed NE and the MG speed NM1 is greater than the differential rotation speed DR, the control device 100 ends the engine stop control. That is, when there may be a problem with the first rotation sensor 51, the release of the clutch 22 and the stop of the internal combustion engine 10 are not executed. Therefore, due to a problem with the first rotation sensor 51, the processes of steps S14 and S15 described above will not be executed unnecessarily.

[0031] [Modification Example] The above embodiment can be implemented with the following modifications. The above embodiment and the following modification examples can be combined and implemented within a technically non - conflicting range.

[0032] · The overall configuration of the vehicle 500 is not limited to the example of the above embodiment. The vehicle 500 only needs to include an internal combustion engine 10, a motor generator 21, a clutch 22, a first rotation sensor 51, a second rotation sensor 52, and a control device 100.

[0033] · In the above embodiment, the value of the specified rotation speed RR is an example. The specified rotation speed RR may be greater than or less than 250 rpm. However, the specified rotation speed RR is a value for detecting the state immediately before the engine speed NE becomes zero. Therefore, the specified rotation speed RR needs to be set to a value smaller than the idle speed.

[0034] · In the above embodiment, the value of the differential rotation speed DR is an example. The differential rotation speed DR may be greater than or less than 100 rpm. · In the above-described embodiment, in step S13, instead of the MG rotation speed NM1, the absolute value of the difference between another rotation speed and the engine rotation speed NE may be calculated. In this case, as long as it is the rotation speed of the shaft that rotates in synchronization with the crankshaft 11, it can be adopted as the above-mentioned "another rotation speed". For example, the internal combustion engine 10 includes a camshaft for driving the intake valve and the exhaust valve. This camshaft is connected to the crankshaft 11 via a sprocket and a chain wound around the sprocket. That is, the rotation speed of the camshaft is synchronized with the crankshaft 11 if it is normal. Therefore, when the absolute value of the difference between the engine rotation speed NE and the rotation speed of the camshaft is equal to or less than the differential rotation speed RR, the processes of step S14 and step S15 may be performed. In this modification example, the same effect as that of the above-mentioned (2) can be obtained.

[0035] The technical idea derivable from the above-described embodiment and modification example is described below. · A vehicle applicable to a vehicle including an internal combustion engine having a crankshaft, a motor generator having an output shaft that is part of a driving force transmission path from the crankshaft to a driving wheel, a clutch interposed between the crankshaft and the output shaft, a camshaft that rotates in synchronization with the rotation of the crankshaft and opens and closes an intake valve or an exhaust valve of the internal combustion engine, a first rotation sensor capable of detecting an engine rotation speed that is the rotation speed of the crankshaft, and a second rotation sensor capable of detecting a cam rotation speed that is the rotation speed of the camshaft, the clutch being switchable between an engaged state in which torque transmission is possible between the crankshaft and the output shaft and a released state in which torque transmission is impossible between the crankshaft and the output shaft, the control device being a control device that controls the internal combustion engine and the clutch, and during driving of the internal combustion engine, when the clutch is in the engaged state, and the engine rotation speed is equal to or lower than a specified rotation speed predetermined as a rotation speed lower than the idle rotation speed, and the absolute value of the difference between the engine rotation speed and the cam rotation speed is equal to or lower than a predetermined differential rotation speed, the clutch is changed to the released state, and fuel injection and ignition in the internal combustion engine are stopped.

Explanation of Reference Numerals

[0036] DR…Differential rotation speed NE…Engine speed NM1…MG rotation speed RR…Specified rotation speed 10…Internal combustion engine 11…Crankshaft 21…Motor generator 22…Clutch 30…Drive wheel 51…First rotation sensor 52…Second rotation sensor 100…Control device 500…Vehicle

Claims

【Claim 1】 An internal combustion engine having a crankshaft, A motor generator having an output shaft that is part of the drive force transmission path from the crankshaft to the drive wheels, A clutch interposed between the crankshaft and the output shaft, A first rotation sensor capable of detecting the engine rotation speed, which is the rotation speed of the crankshaft, A second rotation sensor capable of detecting the MG rotation speed, which is the rotation speed of the motor generator, and comprising, The clutch is applied to a vehicle that can be switched between an engaged state in which torque can be transmitted between the crankshaft and the output shaft and a released state in which torque cannot be transmitted between the crankshaft and the output shaft, A control device that controls the internal combustion engine and the clutch, During driving of the internal combustion engine, when the clutch is in the engaged state, the engine rotation speed is equal to or lower than a specified rotation speed predetermined as a rotation speed lower than the idle rotation speed, and the absolute value of the difference between the engine rotation speed and the MG rotation speed is equal to or lower than a predetermined differential rotation speed, the clutch is changed to the released state, and fuel injection and ignition in the internal combustion engine are stopped, When the absolute value is greater than the differential rotation speed, the clutch is maintained in the engaged state, and driving of the internal combustion engine is continued A control device for a vehicle.

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