Vehicle control device

Abstract

To provide a vehicle control device capable of properly starting regeneration control by allowing more reliable lock-up as a state of charge of a battery is lower and the importance of regeneration is higher.SOLUTION: When executing regeneration control with an electric motor MG by engaging a lock-up clutch 40, a vehicle control device executes control of increasing an engagement hydraulic pressure Plu of the lock-up clutch 40 as a state of charge SOC of a battery 54 is lower. Thus, lock-up is takes place more reliably as the importance of regeneration for charging the battery 54 is higher, allowing proper start of regeneration control.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] In a hybrid vehicle equipped with an engine and an electric motor as a power source for driving, a torque converter and an automatic transmission provided between the power source and the drive wheels, and a battery, a technology has been disclosed that performs regenerative control to improve fuel efficiency when the vehicle is decelerating and the remaining charge of the battery is less than a predetermined value, for example, when the battery is chargeable, by engaging a lock-up clutch of the torque converter, making the electric motor function as a generator, and charging the generated power to the battery. For example, a hybrid vehicle described in Patent Document 1 is such a technology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-178000 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the hybrid vehicle of Patent Document 1, the necessity for implementing regenerative control is determined based on a fixed value of the remaining battery charge, for example, a threshold value for whether charging is possible, and the control is not based on the remaining battery charge. On the other hand, the lower the remaining battery charge, the greater the necessity (importance) of charging becomes, and the more power (charge amount) can be obtained through regenerative control. Therefore, in order to further improve fuel efficiency, it is required to increase the opportunities and frequency of regenerative control by the electric motor as the remaining battery charge decreases.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a hybrid vehicle that can ensure reliable lockup of the lock-up clutch and appropriately start regenerative control during regenerative control when the vehicle decelerates, especially when the remaining charge of the battery is low and regeneration is important. [Means for solving the problem]

[0006] The gist of the present invention is (a) a control device for a vehicle that has an engine and an electric motor as a power source for driving, a torque converter and an automatic transmission with a lock-up clutch provided between the power source and the drive wheels, and a battery, and (b) a regenerative control unit that, when the lock-up clutch is engaged to perform regenerative control by the electric motor during deceleration of the vehicle, controls the engagement oil pressure of the lock-up clutch to be higher the lower the remaining charge of the battery. Effect of the Invention

[0007] According to the vehicle control device of the present invention, when the lock-up clutch is engaged to perform regenerative control by the electric motor during deceleration of the vehicle, the lower the remaining charge of the battery, the higher the engagement oil pressure of the lock-up clutch is controlled. Therefore, the more important regeneration is for charging the battery, the more reliably the lock-up will be achieved, and regenerative control by the electric motor can be started appropriately. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device as a control device according to an embodiment of the present invention; [Diagram 2] 4 is a flowchart illustrating control of an engagement oil pressure of a lock-up clutch in regenerative control by the electronic control device of FIG. 1. [Diagram 3] 2 is a diagram for explaining an example of a map of the state of charge (SOC) of the battery and a lock-up hydraulic pressure addition value in the regenerative control of the electronic control device of FIG. 1. FIG. [Figure 4] 4 is a time chart illustrating a case in which the present invention is not applied and regenerative control is not performed in the regenerative control of the electronic control device in FIG. 1. [Diagram 5] 2 is a time chart illustrating a case where the present invention is applied to the regenerative control of the electronic control device in FIG. 1 and regenerative control is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention is preferably applied to a hybrid vehicle in which, for example, an electric motor is provided alongside an engine and the engine is connected to an automatic transmission via a torque converter, but it may also be applied to a hybrid vehicle in which an electric motor is arranged in series between the engine and the torque converter and a disconnecting clutch is arranged between the engine and the electric motor. EXAMPLES

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic diagram of a drive system of a vehicle 10 equipped with an electronic control device 100 as a control device according to an embodiment of the present invention, and shows control functions for various controls related to the vehicle 10 and essential parts of the control system.

[0011] The vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG as a power source for running. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine, and the engine torque Te is controlled by an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., which is controlled by an electronic control device 100.

[0012] The electric motor MG is operatively connected to the crankshaft of the engine 12 via a belt 20. The electric motor MG is a motor generator having a function as an electric motor and a function as a generator, and is connected to a battery (secondary battery) 54 via an inverter 52. The inverter 52 is controlled by the electronic control device 100, whereby the MG torque Tmg and the MG rotation speed Nmg of the electric motor MG are controlled.

[0013] The battery 54 is an electricity storage device that supplies and receives electric power to the electric motor MG, and is, for example, a high-voltage battery that stores electricity at a voltage of 48 V. A low-voltage battery 58 is connected to the battery 54 via a voltage converter (DC / DC converter) 56. The low-voltage battery 58 is an auxiliary power source for air conditioners, control devices, lighting devices, etc., and stores electricity at a voltage of, for example, 12 V.

[0014] The vehicle 10 includes a power transmission device 16 provided on a power transmission path between an engine 12 and drive wheels 14. The power transmission device 16 includes a torque converter 22 with a lock-up clutch 40 and an automatic transmission 24 arranged in series from the engine 12 side in a case 18 attached to the vehicle body. The torque converter 22 is a fluid-type power transmission device that transmits power via fluid, and includes a lock-up clutch 40 that directly connects input and output rotating members of the torque converter 22. The automatic transmission 24 is, for example, a planetary gear-type stepped transmission having a plurality of hydraulic engagement devices CB. The power transmission device 16 includes a propeller shaft 28, a differential gear 30, a pair of drive shafts 32, and the like.

[0015] The hydraulic control circuit 60 is provided so as to be able to adjust the hydraulic pressure Plu of the hydraulic oil supplied to the lock-up clutch 40, and the hydraulic actuators (not shown) of the automatic transmission 24. The hydraulic control circuit 60 is provided with a plurality of solenoid valves (not shown), and the hydraulic pressure of the hydraulic oil supplied to each of the hydraulic actuators is controlled by controlling the control pressures output from the various solenoid valves based on command signals from the electronic control device 100.

[0016] The vehicle 10 is equipped with an electronic control device 100 as a control device that executes various types of control. The electronic control device 100 includes a so-called microcomputer, and executes various types of control of the vehicle 10 by processing input signals according to pre-stored programs.

[0017] The electronic control device 100 is supplied with the battery temperature THbat (°C), battery charge / discharge current Ibat (A), battery voltage Vbat (V) of the battery 54, engine water temperature THwe (°C) which is the temperature of the engine coolant, and engine oil temperature THoe (°C) which is the temperature of the engine oil, from a battery sensor 84, an engine water temperature sensor 86, and an engine oil temperature sensor 88. The electronic control device 100 also receives the engine rotation speed Ne (rpm) which is the rotation speed of the engine 12, a turbine rotation speed Nt (rpm) which is the same as the transmission input rotation speed Ni (rpm), a transmission output rotation speed No (rpm) which corresponds to the vehicle speed V, an MG rotation speed Nmg (rpm) which is the rotation speed of the electric motor MG, an accelerator opening θacc (%) which is the amount of operation of an accelerator operating member such as an accelerator pedal and which represents the amount of acceleration required by the driver, and an electronic throttle valve opening θacc (%) which is the opening of the electronic throttle valve θt (rpm). Various pieces of information required for various controls, such as a certain throttle valve opening θth (%), are supplied from sensors (not shown).

[0018] The electronic control device 100 functionally comprises a power source control unit 102, a driving mode control unit 104, a gear shift control unit 106, a regeneration control unit 108, etc., in relation to the control of the engine 12 and the electric motor MG.

[0019] The power source control unit 102 calculates the amount of driving demanded by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand map. The amount of driving demand is, for example, a required driving torque Trdem at the driving wheels 14. The power source control unit 102 calculates a required input torque Tindem, which is an input torque of the torque converter 22 required to realize the required driving torque Trdem, and controls the engine 12 and the electric motor MG so as to obtain the required input torque Tindem. The power source control unit 102 performs HEV (Hybrid Electric Vehicle) driving, which runs using only the engine 12 as a power source, or runs using the engine 12 and the electric motor MG as power sources. In this HEV driving, the engine torque Te and the MG torque Tmg are appropriately combined and controlled so as to realize the required input torque Tindem. In addition, the power source control unit 102 performs control to release the idling stop, which rotates the electric motor MG and restarts the engine 12 from the idling stop state of the engine 12 when the vehicle 10 is stopped.

[0020] The driving mode control unit 104 controls whether or not HEV driving is possible. For example, the driving mode control unit 104 controls the driving mode so that HEV driving is possible until the remaining charge SOC of the battery 54 reaches a predetermined lower limit SOCmin, and the driving mode is controlled so that the vehicle runs only on the engine when the remaining charge SOC reaches the lower limit SOCmin. The remaining charge SOC is a value indicating the state of charge of the battery 54, and is calculated, for example, based on the battery charge / discharge current Ibat and the battery voltage Vbat. The lower limit SOCmin is, for example, a value set to ensure a minimum amount of power required to cancel idling stop.

[0021] The shift control unit 106 determines a target gear position of the automatic transmission 24 based on the actual accelerator opening θacc and vehicle speed V from a pre-stored shift map, and selectively engages multiple hydraulic engagement devices CB of the automatic transmission 24 so that the actual gear position becomes the target gear position.

[0022] The regenerative control unit 108 performs regenerative control in which, during deceleration when the accelerator opening θacc becomes 0 (%), the lock-up clutch 40 is engaged to rotate the electric motor MG in response to a regenerative request issued when the battery 54 is accepting charge, such as when the remaining charge SOC falls below a predetermined upper limit value SOCmax, thereby charging the battery 54 with the power generated by regeneration of the electric motor MG.

[0023] 2 is a flowchart illustrating the engagement control of the lock-up clutch 40, which is executed by the regeneration control unit 108 at the start of regeneration control, and is a main part of the control function of the electronic control device 100. The engagement of the lock-up clutch 40 is performed by controlling the hydraulic pressure Plu of the hydraulic oil supplied to the lock-up clutch 40.

[0024] First, in step (hereinafter, step will be omitted) S10, the hydraulic pressure Pa (kPa) required to engage the lock-up clutch 40 is calculated. The hydraulic pressure Pa is calculated by inputting information such as the vehicle speed V, engine rotation speed Ne (rpm), turbine rotation speed Nt (rpm), and the gear position of the automatic transmission 24 into a map or a calculation formula that has been prepared in advance experimentally or by design.

[0025] Next, in S20, a hydraulic pressure addition value Pb (kPa) based on the remaining charge SOC is calculated and added to the hydraulic pressure Pa calculated in S10 (Pa+Pb). The hydraulic pressure addition value Pb is calculated based on the actual remaining charge SOC, for example, from the relationship shown in Fig. 3, which is calculated from a map prepared in advance experimentally or by design. In Fig. 3, the hydraulic pressure addition value Pb is set to a larger value as the remaining charge SOC decreases, and when the remaining charge SOC exceeds a predetermined threshold value SOCadd (%), the hydraulic pressure addition value Pb is set to 0. The threshold value SOCadd is a value that is suitably set in advance experimentally or by design.

[0026] Next, in S30, the calculation result (Pa+Pb) in S20 is sent to the hydraulic control circuit 60 as the target lock-up hydraulic pressure Pluo for the lock-up clutch 40 (Pluo=Pa+Pb).

[0027] By the above-described control, the lower the remaining charge SOC of the battery 54, the higher the target lock-up oil pressure Pluo becomes, and regenerative control is performed with the engagement oil pressure of the lock-up clutch 40 being increased.

[0028] Figures 4 and 5 are time charts explaining the control operation of the regenerative control during vehicle deceleration. Figure 4 shows the case where the control in S20 in Figure 2, which is the main part of the present invention, i.e., the control of hydraulic pressure addition based on the SOC of the remaining charge, is not applied, and Figure 5 shows the case where the control in S20 in Figure 2, i.e., the control of hydraulic pressure addition based on the SOC of the remaining charge, is applied.

[0029] In FIG. 4, first, at time t1, the accelerator is released (accelerator opening θacc=0) to start regenerative control during deceleration, and the calculated hydraulic pressure Pa (see S10 in FIG. 2) is commanded to the hydraulic control circuit 60 as the target lock-up hydraulic pressure Pluo (=Pa), and engagement control of the lock-up clutch 40 is started. Next, at time t2, even if the engine rotation speed Ne (input side) of the lock-up clutch 40 falls below the turbine rotation speed Nt (output side), if the actual lock-up hydraulic pressure Plur of the actual measurement value does not reach the target lock-up hydraulic pressure Pluo, it is determined that lock-up is impossible, lock-up is rejected, and regenerative control is not performed. With the conventional setting of the target lock-up hydraulic pressure Pluo (=Pa), there are cases where the lock-up state cannot be formed due to insufficient hydraulic pressure in response to such a sudden drop in the engine rotation speed Ne when the accelerator is released, leading to an opportunity loss for performing regenerative control.

[0030] On the other hand, in Fig. 5, the target lock-up oil pressure Pluo is a value obtained by adding Pa+Pb as described above (see S20 in Fig. 2). By raising the target lock-up oil pressure Pluo (=Pa+Pb), the actual lock-up oil pressure Plur also rises faster, and at time t11, it reaches the target lock-up oil pressure Pluo (=Pa+Pb), lock-up is performed (engine rotation speed Ne = turbine rotation speed Nt), and regenerative control is performed.

[0031] As described above, according to the electronic control device 100 of the vehicle 10 of this embodiment, when the lock-up clutch 40 is engaged and regenerative control is performed during deceleration of the vehicle 10, the lower the remaining charge SOC of the battery 54, the higher the engagement oil pressure Plu of the lock-up clutch 40 is controlled. Therefore, the more important regeneration is for charging the battery 54, the more reliably the lock-up is achieved, and regenerative control can be started appropriately.

[0032] Although the embodiment of the present invention has been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be embodied in various modified and improved forms. [Explanation of symbols]

[0033] 10: Hybrid vehicle 12: Engine 22: Torque converter 24: Automatic transmission 40: Lock-up clutch 54: Battery 100: Electronic control device 108: Regenerative control unit MG: Electric motor

Claims

[Claim 1] A control device for a vehicle including an engine and an electric motor as a power source for driving the vehicle, a torque converter including a lock-up clutch provided between the power source and a drive wheel, an automatic transmission, and a battery, a regeneration control unit that, when engaging the lock-up clutch to perform regeneration control by the electric motor during deceleration of the vehicle, performs control such that the engagement hydraulic pressure of the lock-up clutch is increased as the remaining charge of the battery decreases. A vehicle control device comprising:

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