Hybrid vehicle control device

Abstract

To provide a hybrid vehicle control device capable of achieving both improved acceleration feeling and reduced vibration.SOLUTION: When a control device of a hybrid vehicle in which an engine and a motor are connected to an input side of an automatic transmission causes the motor to assist in rotation synchronization in downshifting of the automatic transmission in response to a driver's acceleration demand, the control device calculates a release change rate of a clutch mechanism included in the automatic transmission and time required to achieve a reduction to torque capacity in an inertia phase. Then, the control device limits an increase rate so that assist torque can be changed to an upper limit within the time.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses that a control device for a hybrid vehicle performs torque assist by a motor in response to a driver's acceleration request. In the configuration described in Patent Document 1, when a downshift request to increase the gear ratio of the automatic transmission is made in response to a request to increase the driving force of the hybrid vehicle (acceleration request), if it is determined that the allowable shift time is less than a predetermined time, the output torque of the motor connected to the input side of the automatic transmission is increased. This improves shift response and shortens the time it takes for the hybrid vehicle to reach its maximum acceleration. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-001585 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration described in Patent Document 1, the torque on the input side of the automatic transmission, which has been increased to improve shift response, is transmitted downstream of the automatic transmission, which may cause torsional vibration.

[0005] The present invention has been made in view of the above circumstances, and has an object to provide a control device for a hybrid vehicle that can achieve both an improved acceleration feeling and reduced vibrations. [Means for solving the problem]

[0006] The present invention is a control device for a hybrid vehicle in which an engine and a motor are connected to the input side of an automatic transmission, and in the case where the motor assists in downshift rotation synchronization when the automatic transmission is downshifted in response to an acceleration request from the driver, the control device calculates the release change rate of a clutch mechanism included in the automatic transmission, calculates the time required for the torque capacity to decrease to the inertia phase, and limits the increase rate so that the assist torque is changed to an upper limit within the range of the time. [Effects of the Invention]

[0007] The present invention can achieve both an improved acceleration feeling and reduced vibration. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating a hybrid vehicle according to an embodiment. [Figure 2] FIG. 2 is a flowchart showing the downshift control. [Figure 3] FIG. 3 is a time chart for explaining state changes when downshift control is executed.

[0009] Hereinafter, a control device for a hybrid vehicle according to an embodiment of the present invention will be specifically described, but the present invention is not limited to the embodiment described below.

[0010] 1 is a diagram illustrating a hybrid vehicle according to an embodiment. The hybrid vehicle 1 includes an engine (Eng) 2, a first motor (MG1) 3, a second motor (MG2) 4, wheels 5, a torque converter 6, an automatic transmission (AT) 7, and a control unit (ECU) 10.

[0011] The hybrid vehicle 1 is equipped with an engine 2 and two motors 3 and 4 as power sources. Power output from the engine 2 is transmitted to wheels 5 via an automatic transmission 7. In the hybrid vehicle 1, the engine 2 and the first motor 3 are connected to the input side of the automatic transmission 7 via a torque converter 6. The first motor 3 is connected to the engine 2 upstream of the torque converter 6. The torque converter 6 is a torque converter with a lock-up clutch. The second motor 4 is connected downstream of the automatic transmission 7 via a gear 8. In the hybrid vehicle 1, the torque output from the second motor 4 can be added to the torque transmitted from the engine 2 to the wheels 5.

[0012] The automatic transmission 7 is a transmission provided in a power transmission path between the torque converter 6 and the wheels 5. The automatic transmission 7 changes the speed of the power output from the engine 2 and outputs it to the wheels 5. The automatic transmission 7 is configured, for example, as a planetary gear automatic transmission. The automatic transmission 7 includes one or more planetary gear mechanisms and multiple clutch mechanisms CL. The clutch mechanisms CL are gear shift engagement devices and are configured, for example, as hydraulic friction engagement devices. The hybrid vehicle 1 includes a hydraulic actuator that controls the engagement / disengagement state of the clutch mechanisms CL, and a hydraulic control circuit that supplies regulated hydraulic pressure to the hydraulic actuator. In the hybrid vehicle 1, the torque capacity (transmission torque capacity) of the clutch mechanisms CL is changed by the regulated hydraulic pressure supplied from the hydraulic control circuit to the hydraulic actuator. The clutch mechanisms CL can be switched between engagement / disengagement states such as a fully engaged state, a partially engaged state, and a released state. The hydraulic control circuit is controlled by a control device 10.

[0013] The automatic transmission 7 is a stepped transmission in which one of a plurality of gears with different gear ratios is established by engaging one of a plurality of clutch mechanisms CL. A larger gear ratio corresponds to a lower gear, and a smaller gear ratio corresponds to a higher gear. The automatic transmission 7 switches the established gear by switching the engagement / disengagement state of the clutch mechanisms CL involved in gear shifting in response to the driver's accelerator operation and the vehicle speed.

[0014] The control device 10 is an electronic control device that controls the hybrid vehicle 1. The control device 10 includes a microcomputer equipped with a CPU, RAM, ROM, and an input / output interface. The control device 10 processes signals according to a program pre-stored in the ROM. Signals are input to the control device 10 from various sensors mounted on the hybrid vehicle 1. For example, a vehicle speed signal from a vehicle speed sensor that detects the vehicle speed, an accelerator position signal from an accelerator position sensor that detects the amount of accelerator pedal operation, and an engine rotation speed signal from an engine rotation speed sensor that detects the rotation speed of the engine 2 are input to the control device 10. The control device 10 executes various controls based on the signals input from the various sensors. In this case, the control device 10 performs calculations using the input data and pre-stored data and outputs the calculation results as command signals. The control device 10 outputs signals for controlling the engine 2, the first motor 3, the automatic transmission 7, and the second motor 4.

[0015] The control device 10 executes gear shift control. By executing gear shift control, the control device 10 switches the engaged / disengaged state of the clutch mechanism CL involved in the gear shift operation, thereby switching the gear position formed by the automatic transmission 7. The gear shift control includes downshift control and upshift control. The downshift control is gear shift control in which the automatic transmission 7 is shifted to a lower gear position. The upshift control is gear shift control in which the automatic transmission 7 is shifted to a higher gear position.

[0016] When performing downshift control, the control device 10 assists rotation synchronization with the first motor 3. The assist torque of the first motor 3 is determined with the aim of speeding up the downshift, i.e., quickly reaching the target rotation speed. When using the first motor 3 to assist rotation synchronization during this downshift, the control device 10 controls the first motor 3 so that unintended torque is not transmitted downstream of the automatic transmission 7.

[0017] 2 is a flowchart showing the downshift control. The control shown in FIG.

[0018] The control device 10 determines whether the accelerator is on and a downshift is in progress (step S1). In step S1, it is determined based on the accelerator opening whether the driver is requesting acceleration and the automatic transmission 7 is in a downshift setting. The amount of accelerator pedal operation represents the magnitude of the driver's acceleration operation. A downshift is a change to a gear with a larger gear ratio.

[0019] If it is determined that the accelerator is ON and the downshift is not being performed (step S1: No), this control routine ends.

[0020] If it is determined that the accelerator is ON and a downshift is occurring (step S1: Yes), the control device 10 calculates the assist torque according to the difference in rotation from the target rotation speed after the downshift (step S2). In step S2, the assist torque is calculated according to the difference in rotation between the current engine rotation speed and the target engine rotation speed after the downshift. The control device 10 calculates a larger assist torque as the difference in rotation from the target rotation speed after the downshift increases, and calculates a smaller assist torque as the difference in rotation from the target rotation speed after the downshift decreases.

[0021] The control device 10 calculates the release change rate of the clutch mechanism CL in the automatic transmission 7 (step S3). The control device 10 calculates the release change rate of the clutch mechanism CL by extracting information from a pre-adapted map or by detecting it from the actual change rate. Furthermore, the control device 10 calculates the time Δt required for the torque capacity of the clutch mechanism CL to decrease to the torque capacity in the inertia phase. For example, the control device 10 calculates the amount of change in torque capacity ΔpCL based on the torque capacity of the clutch mechanism CL at the timing of transition to the inertia phase and the torque capacity in the inertia phase. The control device 10 calculates the time Δt based on the release change rate of the clutch mechanism CL and the amount of change in torque capacity ΔpCL.

[0022] The control device 10 executes rate processing of the assist torque (step S4). The control device 10 limits the rate of increase of the assist torque so that it changes to the upper limit ΔTg of the assist torque in the time Δt calculated in step S3. By limiting the rate of increase of the assist torque, the torque increased on the input side of the automatic transmission 7 due to the assist torque is less likely to be transmitted downstream of the automatic transmission 7. Since the torque applied before the clutch mechanism CL is fully released is not used to increase the rotation speed, limiting the rate of increase of the assist torque has little effect on shortening the time for rotation synchronization. After the processing of step S4 is performed, this control routine ends.

[0023] FIG. 3 is a time chart illustrating state changes when downshift control is executed. FIG. 3 shows state changes in the example, the first comparative example, and the second comparative example. The example involves rate processing of the assist torque by the control device 10. The first comparative example involves applying assist torque when downshifting with the accelerator pedal on, but does not involve rate processing of the assist torque. The second comparative example involves not applying assist torque when downshifting with the accelerator pedal on.

[0024] As shown in FIG. 3, when downshift control is initiated, the system transitions to the inertia phase (time t1). At the timing of the transition to the inertia phase, the assist torque is calculated. The assist torque T1 with rate processing in the embodiment is shown by a solid line. The assist torque T2 without rate processing in the first comparative example is shown by a dashed line, and the assist torque T3 without assistance in the second comparative example is shown by a dashed line. The assist torque is calculated based on the differential rotation between the current engine speed and the target speed after the downshift. The engine speed Ne1 in the embodiment is shown by a solid line, the engine speed Ne2 in the first comparative example is shown by a dashed line, the engine speed Ne3 in the second comparative example is shown by a dashed double-dot line, and the target speed Ne4 after the downshift is shown by a dashed line.

[0025] Also, at time t1, the time Δt required for the torque capacity to decrease to the inertia phase is calculated. The change in torque capacity ΔpCL is calculated based on the torque capacity of the clutch mechanism CL at the time of transition to the inertia phase and the torque capacity in the inertia phase. The time Δt is calculated based on the release change rate of the clutch mechanism CL and the change in torque capacity ΔpCL. The torque capacity Tc12 transitioning from the engaged side to the disengaged side in the example and the first comparative example is indicated by a thick dashed line, while the torque capacity Tc22 transitioning from the disengaged side to the engaged side in the example and the first comparative example is indicated by a thin dashed line. The torque capacity Tc13 transitioning from the engaged side to the disengaged side in the second comparative example is indicated by a thick dashed line, while the torque capacity Tc23 transitioning from the disengaged side to the engaged side in the second comparative example is indicated by a thin dashed line. As can be seen from the change in torque capacity, when there is assist torque, the downshift is completed earlier than when there is no assist torque.

[0026] The transmission output torque shown in FIG. 3 represents the torque output downstream from the automatic transmission 7. A large transmission output torque in the inertia phase indicates the occurrence of torsional vibration during downshift control. The transmission output torque T31 of the embodiment with rate processing is smaller than the transmission output torque T32 of the first comparative example without rate processing. The embodiment can reduce torsional vibration more than the first comparative example. The transmission output torque T31 of the embodiment is shown by a solid line, the transmission output torque T32 of the first comparative example is shown by a dashed line, and the transmission output torque T33 of the second comparative example is shown by a dashed line.

[0027] The vehicle acceleration α1 of the embodiment is shown by a solid line, the vehicle acceleration α2 of the first comparative example is shown by a dashed line, and the vehicle acceleration α3 of the second comparative example is shown by a dashed double-dashed line. The time it takes for the vehicle acceleration to reach a peak is the same for the embodiment as for the first comparative example. However, the fluctuations in vehicle acceleration in the first comparative example are larger than those of the embodiment. In contrast, the embodiment exhibits vibrations (fluctuations in vehicle acceleration) equivalent to those of the second comparative example without assistance.

[0028] As described above, according to the embodiment, when the rotation synchronization during downshifting is assisted by the motor, it is possible to achieve both an improved acceleration feeling and reduced vibration. [Explanation of symbols]

[0029] 1 Hybrid vehicle 2 Engine 3. First motor (MG1) 4 Second motor (MG2) 5 wheels 6 Torque converter 7 Automatic transmission (AT) 10 Control Unit (ECU)

Claims

[Claim 1] A control device for a hybrid vehicle in which an engine and a motor are connected to the input side of an automatic transmission, When the automatic transmission is downshifted in response to an acceleration request from a driver, the motor assists in downshift rotation synchronization, calculating a release change rate of a clutch mechanism included in the automatic transmission; Calculate the time required for the torque capacity to decrease to the inertia phase. The rate of increase is limited so that the assist torque is changed to the upper limit within the time range. A control device for a hybrid vehicle.

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