Hybrid vehicle control device

Abstract

To provide a hybrid-vehicular control apparatus for suppressing a torque shock from occurring.SOLUTION: A hybrid-vehicular control apparatus is applied to a hybrid vehicle that includes an engine and a motor as drive sources and switches a travel mode between a motor mode in which the motor is used as a driving source for traveling and an engine mode in which the engine is used as a driving source for traveling. The control apparatus includes: a determination part for determining whether there is a deceleration request in a case where the travel mode is the motor mode; and a motor control part for controlling motor braking torque on the basis of a motor rotation speed by executing a regenerative operation of the motor. Further, the motor control part causes the motor braking torque to corresponds with engine braking torque applied in the case of the travel mode being the engine mode, with the engine revolution speed being the motor rotation speed, and with a fuel cut being executed in the engine.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] Hybrid vehicles equipped with an engine and a motor as drive sources are known. In such hybrid vehicles, the driving mode can be switched between a motor mode in which the vehicle runs using the motor as a drive source and an engine mode in which the vehicle runs using the engine as a drive source. When a deceleration request is made while the vehicle is running in the motor mode, the motor is operated regeneratively to generate motor braking torque, thereby achieving deceleration. When a deceleration request is made while the vehicle is running in the engine mode, fuel is cut to generate engine braking torque, thereby achieving deceleration (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-180695 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, if the mode is switched from the motor mode to the engine mode during deceleration, a torque shock may occur.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, an object of the present invention is to provide a control device for a hybrid vehicle that suppresses the occurrence of torque shock. [Means for solving the problem]

[0006] The above object is to provide a vehicle equipped with an engine and a motor as a driving source. A K0 clutch and the motor are provided in this order in the power transmission path from the engine to the wheels. Applied to hybrid vehicles, Release the K0 clutch A motor mode in which the motor is used as a driving source; or The K0 clutch is engaged.In the control device for a hybrid vehicle, a drive mode is switched to an engine mode in which the vehicle runs using the engine as a drive source. The control device further includes a determination unit that determines whether or not a deceleration request is made when the drive mode is the motor mode, and a regenerative operation of the motor is performed when a positive determination is made by the determination unit. The torque of the motor is Motor braking torque based on motor speed To A motor control unit controls the driving mode. Based on the engine braking torque at the time of fuel cut execution, which approaches 0 as the engine speed decreases when the mode is the engine mode, The motor control unit controls the motor braking torque as follows: When the motor speed is the same as the engine speed, Corresponding to engine braking torque When the switching control from the motor mode to the engine mode is started and the K0 clutch is in a slip state, the motor control unit increases the torque of the motor from the motor braking torque by a predetermined torque required for cranking the engine, and when the K0 clutch is engaged and the switching from the motor mode to the engine mode is completed, the motor torque is controlled to 0 and fuel is cut off in the engine. This can be achieved by a control device for a hybrid vehicle. Effect of the Invention

[0007] According to the present invention, it is possible to provide a control device for a hybrid vehicle that suppresses the occurrence of torque shock. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Diagram 2] FIG. 2 is a timing chart showing an example of deceleration control of the engine and the motor. [Diagram 3] FIG. 3 is a flowchart showing an example of the deceleration control of the motor executed by the ECU. [Figure 4] FIG. 4 is a map that defines the relationship between engine braking torque and engine speed due to fuel cut. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] [General configuration of hybrid vehicle] FIG. 1 is a schematic diagram of a hybrid vehicle 1. In the hybrid vehicle 1, a K0 clutch 14, a motor 15, a torque converter 18, and an automatic transmission 19 are provided in this order in a power transmission path from an engine 10 to wheels 13. The engine 10 and the motor 15 are mounted on the hybrid vehicle 1 as a driving source. The engine 10 is, for example, a V6 gasoline engine, but the number of cylinders is not limited thereto, and may be an in-line engine or a diesel engine. The K0 clutch 14, the motor 15, the torque converter 18, and the automatic transmission 19 are provided in a transmission unit 11. The transmission unit 11 and the left and right wheels 13 are drivingly connected via a differential 12.

[0010] The K0 clutch 14 is provided between the engine 10 and the motor 15 on the power transmission path. The K0 clutch 14 is engaged when hydraulic pressure is applied, connecting the power transmission between the engine 10 and the motor 15. The K0 clutch 14 is released when the hydraulic pressure supply is stopped, disconnecting the power transmission between the engine 10 and the motor 15.

[0011] The motor 15 is connected to the battery 16 via an inverter 17. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the battery 16, and also functions as a generator that generates electric power to charge the battery 16 in response to power transmission from the engine 10 and the wheels 13. The electric power exchanged between the motor 15 and the battery 16 is adjusted by the inverter 17.

[0012] The inverter 17 is controlled by an ECU 40, which will be described later, and converts the DC voltage from the battery 16 into an AC voltage, or converts the AC voltage from the motor 15 into a DC voltage. In the case of powering operation in which the motor 15 outputs torque, the inverter 17 converts the DC voltage of the battery 16 into an AC voltage and adjusts the power supplied to the motor 15. In the case of regenerative operation in which the motor 15 generates power, the inverter 17 converts the AC voltage from the motor 15 into a DC voltage and adjusts the power supplied to the battery 16.

[0013] The torque converter 18 is a fluid coupling having a torque amplifying function. The automatic transmission 19 is a stepped automatic transmission that switches the gear ratio in multiple stages by switching the gear stage. The automatic transmission 19 is provided between the motor 15 and the wheels 13 on the power transmission path. The motor 15 and the automatic transmission 19 are connected via the torque converter 18. The torque converter 18 is provided with a lock-up clutch 20 that is supplied with hydraulic pressure and enters an engaged state to directly connect the motor 15 and the automatic transmission 19.

[0014] The transmission unit 11 is further provided with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lock-up clutch 20 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is provided with hydraulic circuits for each of the K0 clutch 14, the torque converter 18, the automatic transmission 19, and the lock-up clutch 20, and various hydraulic control valves for controlling the operating hydraulic pressures thereof.

[0015] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 40 as a control device for the vehicle. The ECU 40 is an electronic control unit including a calculation processing circuit that performs various calculation processes related to vehicle driving control, and a memory that stores control programs and data. The ECU 40 is an example of a control device for a hybrid vehicle, and functionally realizes a determination unit and a motor control unit, which will be described in detail later.

[0016] The ECU 40 controls the operation of the engine 10 and the motor 15. For example, the ECU 40 controls the torque and rotation speed of the engine 10 by controlling the throttle opening, ignition timing, and fuel injection amount of the engine 10. The ECU 40 also controls the operation of the K0 clutch 14, the lock-up clutch 20, and the automatic transmission 19 through the control of the hydraulic control mechanism 22.

[0017] The ECU 40 controls the inverter 17 to adjust the amount of power exchanged between the motor 15 and the battery 16, thereby controlling the rotation speed and torque of the motor 15. As will be described in detail later, the ECU 40 also controls the power supplied by the inverter 17 from the motor 15 to the battery 16 so that the motor braking torque during regenerative operation reaches a target value.

[0018] The ECU 40 receives signals from an ignition switch 31, a crank angle sensor 32, a motor revolution speed sensor 33, an accelerator opening sensor 34, a brake opening sensor 35, a SOC (State Of Charge) sensor 36, and the like. The crank angle sensor 32 detects the rotation speed of a crankshaft of the engine 10. The motor revolution speed sensor 33 detects the rotation speed of an output shaft of the motor 15. The accelerator opening sensor 34 detects the accelerator pedal opening, which is the amount of depression of the accelerator pedal by the driver. The brake opening sensor 35 detects the brake pedal opening, which is the amount of depression of the brake pedal by the driver. The SOC sensor 36 detects the SOC of the battery 16. The SOC indicates the remaining amount of electricity stored in the battery 16, and is, for example, a ratio of the current amount of electricity stored to the amount of electricity stored in a fully charged state, expressed as 0 to 100%.

[0019] The ECU 40 runs the hybrid vehicle in either a motor mode or a hybrid mode. In the motor mode, the ECU 40 releases the K0 clutch 14 and uses the motor 15 as a drive source. In the hybrid mode, the ECU 40 engages the K0 clutch 14 and uses at least the engine 10 as a drive source. Specifically, the hybrid mode includes a mode in which the vehicle runs using the engine 10 as a drive source, and a mode in which the motor 15 is powered and both the engine 10 and the motor 15 are used as drive sources. In this specification, the mode in which the vehicle runs using the engine 10 as a drive source, which is included in the hybrid mode, is referred to as the engine mode.

[0020] The driving mode is switched based on the vehicle's required driving force calculated from the vehicle speed and accelerator opening, and the state of charge of the battery 16. For example, when the required driving force is relatively small and the SOC of the battery 16 is relatively high, the electric driving mode in which the engine 10 is stopped is selected to improve fuel efficiency. When the required driving force is relatively large or the SOC of the battery 16 is relatively low, the hybrid driving mode in which at least the engine 10 is driven is selected.

[0021] For example, when there is a deceleration request in the motor mode, regenerative operation is performed by the motor 15, and deceleration is realized by the motor braking torque while the generated power of the motor 15 is charged to the battery 16. However, if the SOC of the battery 16 becomes 100% during such deceleration, the generated power of the motor 15 cannot be further charged to the battery 16, and as a result, deceleration by the regenerative operation cannot be continued. Therefore, in such a case, the ECU 40 switches from the motor mode to the engine mode and executes fuel cut in the engine 10, and continues deceleration by the engine braking torque generated by the fuel cut. When switching from the motor mode to the engine mode during such deceleration, the ECU 40 executes control to suppress the occurrence of torque shock due to the difference between the motor braking torque and the engine braking torque.

[0022] [Engine and motor deceleration control] Next, the deceleration control of the engine 10 and the motor 15 executed by the ECU 40 will be described. FIG. 2 is a timing chart showing an example of the deceleration control of the engine 10 and the motor 15. FIG. 2 shows the engine speed [rpm], the motor speed [rpm], the engine torque [Nm], the motor torque [Nm], the system shaft torque [Nm], and the state of the K0 clutch 14. In FIG. 2, the motor speed and the motor torque are shown by solid lines, the engine speed and the engine torque are shown by dotted lines, and the system shaft torque is shown by dashed lines. The system shaft torque is the torque of the entire hybrid vehicle 1, and corresponds to the sum of the engine torque and the motor torque. FIG. 2 shows a case where the mode is changed from the motor mode to the engine mode during deceleration.

[0023] At time t0, in motor mode, the accelerator and brake are OFF and deceleration is occurring, the motor 15 is in regenerative operation, and a motor braking torque is generated that makes the motor torque a negative torque. In this embodiment, the motor braking torque approaches 0 as the motor rotation speed decreases, but this will be described in detail later. As described above, in motor mode, the K0 clutch 14 is in a released state, and the engine 10 is stopped, so the engine torque and engine rotation speed are both 0.

[0024] When the SOC of the battery 16 reaches 100% at time t1, control for switching from the motor mode to the engine mode is started. Specifically, hydraulic pressure is supplied from the oil pump 21, the K0 clutch 14 goes into a slip state, cranking of the engine 10 by the motor 15 starts, and the engine speed increases. The motor torque at this time is increased from the motor braking torque by an amount of torque required for cranking the engine 10 that is determined in advance. This causes the motor torque to change from negative to positive. Note that the system shaft torque Tilt of is constant because the torque consumed for cranking is simply added to the motor braking torque.

[0025] When the K0 clutch 14 is engaged at time t2, the engine speed and the motor speed become the same value, and the switch from the motor mode to the engine mode is completed. That is, the power supply to the motor 15 is stopped and the motor torque becomes zero. The engine 10 is subjected to a fuel cut, and deceleration continues due to the engine braking torque that makes the engine torque a negative value. Moreover, the engine braking torque due to the fuel cut approaches zero as the engine speed decreases.

[0026] At time t3, when the engine speed falls to or below the return speed α for executing the return control from the fuel cut, fuel injection and ignition are performed and firing starts. As a result, the engine torque changes from negative to positive and increases, and the engine speed and motor speed increase.

[0027] As described above, the engine braking torque from time t2 to t3 is superimposed on the extension line of the motor braking torque from time t0 to t1. Here, the engine braking torque due to fuel cut is almost uniquely determined by the engine speed, and approaches 0 as the engine speed decreases as described above. In contrast, the motor braking torque can be variably controlled to an arbitrary value by controlling the power supplied from the motor 15 to the battery 16 by the inverter 17. Therefore, in this embodiment, To match the engine braking torque according to engine speed Motor Braking Torque but It is variably controlled.

[0028] This suppresses the occurrence of torque shock caused by the difference between the motor braking torque and the engine braking torque when switching from the motor mode to the engine mode during deceleration.

[0029] [Motor deceleration control performed by the ECU] 3 is a flowchart showing an example of deceleration control of the motor 15 executed by the ECU 40. This control is repeatedly executed at predetermined intervals with the ignition on. First, the ECU 40 judges whether or not there is a deceleration request in the motor mode (step S1). If the answer is No in step S1, this control is terminated. The process of step S1 is an example of a process executed by the judgment unit.

[0030] If the answer is Yes in step S1, the ECU 40 acquires the motor rotation speed based on the detection value of the motor rotation speed sensor 33 (step S2) and calculates the engine braking torque (step S3). The calculation of the engine braking torque is performed with reference to the map of FIG. 4. FIG. 4 is a map that specifies the relationship between the engine braking torque and the engine rotation speed due to the fuel cut. The vertical axis indicates the engine braking torque, and the horizontal axis indicates the engine rotation speed. As shown in FIG. 4, the engine braking torque approaches 0 as the engine rotation speed decreases. The map of FIG. 4 is calculated in advance by experiments and stored in the memory of the ECU 40. Note that the map of FIG. 4 is an example, and the relationship between the engine braking torque and the engine rotation speed is not limited to a linear relationship, and may be, for example, a curved relationship. Also, the engine braking torque due to the fuel cut may be calculated by an arithmetic expression using the engine rotation speed as an argument instead of the map of FIG. 4.

[0031] Next, the ECU 40 executes regenerative operation of the motor 15 so that the motor braking torque corresponds to the calculated engine braking torque (step S4). Specifically, the target value of the motor braking torque is set to the engine braking torque, and the ECU 40 controls the inverter 17 to control the power supplied from the motor 15 to the battery 16 so that the motor braking torque becomes the target value. This makes it possible to suppress a torque shock when switching from the motor mode to the engine mode. Steps S2 to S4 are an example of processing executed by the motor control unit.

[0032] Next, the ECU 40 determines whether the SOC of the battery 16 is less than 100% based on the detection value of the SOC sensor 36 (step S5). If the result in step S5 is Yes, this control ends. If the result in step S5 is No, the ECU 40 switches from the motor mode to the engine mode (step S6).

[0033] In the above embodiment, the motor braking torque is controlled to correspond to the engine braking torque, but the motor braking torque does not have to be exactly the same as the engine braking torque. For example, the motor braking torque may deviate from the engine braking torque by a few percent within a range in which no torque shock occurs.

[0034] In the above embodiment, the torque shock that occurs when switching from the motor mode to the engine mode is described as an example, but this is not limited to this, and the torque shock that occurs when switching from the engine mode to the motor mode can also be suppressed.

[0035] In the above embodiment, a hybrid vehicle is controlled by a single ECU 40, but this is not limited to the above, and the above-mentioned control may be performed by multiple ECUs, such as an engine ECU that controls the engine 10, a motor ECU that controls the motor 15, a clutch ECU that controls the K0 clutch 14, and a battery ECU that controls the battery 16.

[0036] 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 described in the claims. [Explanation of symbols]

[0037] 10 Engine 14 K0 clutch 15 Motor 16 Battery 17 Inverter 40 ECU (judgment unit, motor control unit)

Claims

[Claim 1] A control device for a hybrid vehicle that is applied to a hybrid vehicle that has an engine and a motor as drive sources, and in which a K0 clutch and the motor are provided in this order in a power transmission path from the engine to wheels, and that switches a driving mode between a motor mode in which the K0 clutch is released and the vehicle runs using the motor as a drive source, and an engine mode in which the K0 clutch is engaged and the vehicle runs using the engine as a drive source, a determination unit that determines whether or not a deceleration request is present when the driving mode is the motor mode; a motor control unit that, when a positive determination is made by the determination unit, executes a regenerative operation of the motor and controls a torque of the motor to a motor braking torque based on a motor rotation speed, based on an engine braking torque at the time of fuel cut execution, which approaches 0 as the engine rotation speed decreases when the traveling mode is the engine mode, the motor control unit causes the motor braking torque to correspond to an engine braking torque when the motor rotation speed is the same as the engine rotation speed; When the switching control from the motor mode to the engine mode is started and the K0 clutch is in a slip state, the motor control unit increases the torque of the motor from the motor braking torque by a predetermined torque required for cranking the engine, A control device for a hybrid vehicle, which controls the torque of the motor to 0 and executes a fuel cut in the engine when the K0 clutch is engaged and switching from the motor mode to the engine mode is completed.

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