Control device for hybrid vehicle

Abstract

To provide a control device for a vehicle capable of easily miniaturizing a power interrupting mechanism.SOLUTION: The hybrid vehicle 10 includes an engine 12 and an electric motor MG as power sources for running, and an automatic transmission 20, a power interrupting mechanism 22 having a synchromesh mechanism S, and the electric motor MG are provided in this order from the engine 12 side on a power transmission path PT between the engine 12 and a pair of drive wheels 14. The electronic control device 90 (a) brings the power interrupting mechanism 22 into the engaged state in the HEV drive mode in which the engine 12 is used as the power source, (b) brings the power interrupting mechanism 22 into the disengaged state in the BEV drive mode in which the engine 12 is not used as the power source and the electric motor MG is used as the power source, and (c) switches the power interrupting mechanism 22 from the engaged state to the disengaged state after reducing the torque on the engine 12 side in the power interrupting mechanism 22 when switching from the HEV drive mode to the BEV drive mode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle in which, in order from the engine side, an automatic transmission, a power interrupter with a synchromesh mechanism, and an electric motor are provided on a power transmission path between an engine and a pair of drive wheels. [Background technology]

[0002] Hybrid vehicles are known in which, in order from the engine side, an automatic transmission, a clutch, a transfer case, and an electric motor are provided on a power transmission path between an engine and a pair of rear drive wheels. For example, the hybrid vehicle described in Patent Document 1 is such a vehicle. The vehicle described in Patent Document 1 allows selection between an HEV (Hybrid Electric Vehicle) driving mode and a BEV (Battery Electric Vehicle) driving mode. The HEV driving mode is a driving mode in which at least the engine is used as a driving power source. The BEV driving mode is a driving mode in which the engine is not used as a driving power source and the electric motor is used as a driving power source. The vehicle described in Patent Document 1 discloses that, when switching from the HEV driving mode to the BEV driving mode, the clutch is controlled from an engaged state (connected state) to a released state (disconnected state). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-36808 Summary of the Invention [Problem to be solved by the invention]

[0004] In the vehicle described in Patent Document 1, the clutch serving as the power interrupter mechanism may be, for example, a dog clutch employing a synchromesh mechanism (synchronization mechanism) to enable smooth engagement. When switching from HEV driving mode to BEV driving mode with a dog clutch employing a synchromesh mechanism, if the dog clutch is to be released while torque is being transmitted from the engine, a large switching thrust is required in the dog clutch switching mechanism. This is because, when torque from the engine is being transmitted to the dog clutch, the frictional force between the engaging portions of the dog clutch is greater than when torque is not being transmitted. The need for a large switching thrust in the dog clutch switching mechanism means that a device with a large switching thrust is required, which may make it difficult to miniaturize the power interrupter mechanism.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that can easily reduce the size of a power interrupter mechanism. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a hybrid vehicle that has an engine and an electric motor as power sources for driving, and that has, in order from the engine side, an automatic transmission, a power interrupter mechanism having a synchromesh mechanism, and the electric motor provided on a power transmission path between the engine and a pair of drive wheels, wherein (a) in an HEV driving mode in which the engine is used as a power source, the power interrupter mechanism is engaged, (b) in a BEV driving mode in which the engine is not used as a power source and the electric motor is used as a power source, the power interrupter mechanism is disengaged, and (c) when switching from the HEV driving mode to the BEV driving mode, the torque on the engine side of the power interrupter mechanism is reduced, and then the power interrupter mechanism is switched from the engaged state to the disengaged state. [Effects of the Invention]

[0007] According to the hybrid vehicle control device of the present invention, (a) in an HEV driving mode in which the engine is used as a power source, the power interrupter is engaged; (b) in a BEV driving mode in which the engine is not used as a power source and the electric motor is used as a power source, the power interrupter is disengaged; and (c) when switching from the HEV driving mode to the BEV driving mode, the engine-side torque of the power interrupter is reduced, and then the power interrupter is switched from the engaged state to the disengaged state. In this way, the power interrupter is switched from the engaged state to the disengaged state after the engine-side torque of the power interrupter is reduced. By reducing the engine-side torque of the power interrupter, the frictional force between the engaging portions of the power interrupter is reduced. Therefore, a large switching thrust is not required in the switching mechanism of the power interrupter compared to when the power interrupter is switched from the engaged state to the disengaged state without reducing the engine-side torque of the power interrupter. This facilitates miniaturization of the power interrupter. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a hybrid vehicle equipped with an electronic control device according to an embodiment of the present invention, and is a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle. [Figure 2] 4 is an example of a flowchart illustrating a control operation of an electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] 1 is a schematic configuration diagram of a hybrid vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention, and is also a functional block diagram showing the main parts of control functions for various controls in the hybrid vehicle 10. Hereinafter, the "hybrid vehicle 10" will be simply referred to as the "vehicle 10."

[0011] The vehicle 10 includes an engine 12 and an electric motor MG as power sources for traveling. The vehicle 10 includes, in order from the engine 12 side, an automatic transmission 20, a power interrupter 22, an electric motor MG, and a differential gear 24 on a power transmission path PT between the engine 12 and a pair of drive wheels 14, all of which are well-known components. The vehicle 10 also includes a switching mechanism 40, an inverter 50, a battery 52, and an electronic control device 90.

[0012] The engine 12 is a well-known internal combustion engine. The electric motor MG is, for example, a so-called motor generator, and is a three-phase synchronous motor. The electric motor MG is rotationally driven by electric power stored in a battery 52 via an inverter 50.

[0013] The automatic transmission 20 is a well-known automatic transmission that changes the speed of driving power input from the engine 12 and outputs the power. The automatic transmission 20 is controlled by an electronic control unit 90 so that a desired gear ratio γat is formed from among different gear ratios γat. The gear ratio γat is the ratio (=Nin / Nout) of the rotation speed Nin [rpm] of the input shaft to the rotation speed Nout [rpm] of the output shaft in the automatic transmission 20. In this specification, driving force, power, force (=power), and torque are synonymous unless otherwise distinguished. The automatic transmission 20 can also be controlled by the electronic control unit 90 to be in a neutral state.

[0014] The power interrupter 22 is an engagement device that can control the connection and disconnection of the automatic transmission 20 and the electric motor MG. Specifically, one end of the power interrupter 22 is connected to a transmission output shaft 30, which is the output shaft of the automatic transmission 20, and the other end is connected to an electric motor connecting shaft 32, which is the rotor shaft of the electric motor MG. That is, the power interrupter 22 connects and disconnects the power transmission between the transmission output shaft 30 and the electric motor connecting shaft 32. The power interrupter 22 is an engagement device having a synchromesh mechanism S, for example, a dog clutch D having a synchromesh mechanism S. The synchromesh mechanism S is a well-known mechanism that enables engagement after synchronizing the rotational speeds of rotating members with different rotational speeds. The power interrupter 22 is a dog clutch that is engaged by a sleeve after the rotational speeds are approximately matched using, for example, a synchronizer cone or a synchronizer ring as a clutch.

[0015] The switching mechanism 40 is a mechanism that switches the dog clutch D of the power interrupter 22 from one of an engaged state and a released state to the other. For example, the switching mechanism 40 has a well-known configuration that includes a shift fork 44 for switching the dog clutch D from one of an engaged state and a released state to the other, and an actuator 42 that moves the position of the shift fork 44.

[0016] The electronic control unit 90 includes, for example, a so-called microcomputer, and performs signal processing in accordance with pre-stored programs to execute various controls of the vehicle 10. The electronic control unit 90 corresponds to the "control unit" of the present invention.

[0017] The electronic control device 90 outputs various command signals (such as an engine control signal Se that controls the operating state of the engine 12, a shift control signal Sat that controls the shifting of the automatic transmission 20, a clutch control signal Sclu that switches the mesh clutch D from one of an engaged state and a released state to the other, and an electric motor control signal Smg that controls the operating state of the electric motor MG via the inverter 50) to each device of the vehicle 10 (such as the engine 12, the automatic transmission 20, the actuator 42, and the inverter 50).

[0018] The vehicle 10 can be selectively switched between a BEV (Battery Electric Vehicle) driving mode, in which the engine 12 is not used as a power source and the electric motor MG is used as a power source, and an HEV (Hybrid Electric Vehicle) driving mode, in which at least the engine 12 is used as a power source. The HEV driving mode includes a driving mode in which both the engine 12 and the electric motor MG are used as power sources, and a driving mode in which the electric motor MG is not used as a power source and the engine 12 is used as a power source.

[0019] In the BEV driving mode, the power interrupter 22 is disengaged. In the HEV driving mode, the power interrupter 22 is engaged. In the HEV driving mode in which only the engine 12 is used as a power source, the rotor of the electric motor MG is rotated by the power output from the engine 12. That is, even in a non-driving state, the electric motor MG can be rotated by the engine 12 to generate power. The "non-driving state" refers to a state in which the electric motor MG is not controlled by the inverter 50 to output power torque.

[0020] Next, the control when switching from the HEV driving mode to the BEV driving mode will be described.

[0021] The electronic control device 90 determines whether a mode switch from HEV driving to BEV driving has been requested. For example, when the vehicle state changes from a high vehicle speed region where the vehicle speed V [km / h] is relatively high or a high load region where the accelerator pedal depression θacc [%] is relatively high to a low vehicle speed region where the vehicle speed V is relatively low and the accelerator pedal depression θacc is relatively low, a mode switch from HEV driving to BEV driving has been requested. For example, when the state of charge value SOC [%] of the battery 52 (= the ratio of the amount of charge actually stored to a predetermined full charge capacity) exceeds a predetermined determination state value SOC_jdg, a mode switch from a driving mode in which only the engine 12 is used as a power source during HEV driving to BEV driving has been requested. The predetermined judgment state value SOC_jdg is an upper limit target value of the state of charge value SOC of the battery 52, and is a judgment value that is determined in advance experimentally or by design as a judgment value of the state of charge value SOC for forcibly discharging the battery 52 in order to prevent deterioration of the battery 52 due to overcharging of the battery 52.

[0022] When the electronic control unit 90 determines that there is a request to switch the mode from the HEV driving mode to the BEV driving mode, it reduces the torque [N·m] on the engine 12 side of the power interrupter mechanism 22. The "torque on the engine 12 side of the power interrupter mechanism 22" refers to the torque input to the power interrupter mechanism 22 from the engine 12 side. For example, the electronic control unit 90 reduces the torque on the engine 12 side of the power interrupter mechanism 22 by switching the engine 12 to an idling state. For example, the electronic control unit 90 reduces the torque on the engine 12 side of the power interrupter mechanism 22 by switching the automatic transmission 20 to a neutral state. After reducing the torque on the engine 12 side of the power interrupter mechanism 22, the electronic control unit 90 switches the power interrupter mechanism 22 from an engaged state to a disengaged state. After switching the power interrupter mechanism 22 to the disengaged state, the electronic control unit 90 switches the driving mode from the HEV driving mode to the BEV driving mode.

[0023] Fig. 2 is an example of a flowchart illustrating the control operation of the electronic control unit 90. The flowchart in Fig. 2 is repeatedly executed while the HEV is running.

[0024] First, in step S10 (hereinafter, step will be omitted), it is determined whether or not there has been a request for a mode transition from HEV driving mode to BEV driving mode, i.e., a mode switch. If the determination in S10 is YES, then in S20, the torque on the engine 12 side of the power interrupter 22 is reduced. After S20 is executed, in S30, the power interrupter 22 is switched from an engaged state to a disengaged state. After S30 is executed, then in S40, the driving mode is switched from the HEV driving mode, in which the engine 12 is used as a power source, to the BEV driving mode, in which only the electric motor MG is used as a power source. If the determination in S10 is NO or after S40 is executed, the process returns.

[0025] According to this embodiment, the vehicle 10 includes an engine 12 and an electric motor MG as power sources for traveling, and an automatic transmission 20, a power interrupter 22 having a synchromesh mechanism S, and the electric motor MG are provided on a power transmission path PT between the engine 12 and a pair of drive wheels 14, in this order from the engine 12 side. The electronic control device 90 (a) engages the power interrupter 22 in the HEV driving mode, (b) disengages the power interrupter 22 in the BEV driving mode, and (c) when switching from the HEV driving mode to the BEV driving mode, reduces the torque on the engine 12 side of the power interrupter 22 and then switches the power interrupter 22 from the engaged state to the disengaged state. Reducing the torque on the engine 12 side of the power interrupter 22 reduces the frictional force between the engaging portions of the power interrupter 22. Therefore, compared to when the power interrupter mechanism 22 is switched from the engaged state to the released state without reducing the torque on the engine 12 side in the power interrupter mechanism 22, a large switching thrust is not required in the switching mechanism 40 of the power interrupter mechanism 22. This makes it easy to reduce the size of the power interrupter mechanism 22.

[0026] According to this embodiment, the electronic control device 90 switches the power interrupter 22 from the engaged state to the disengaged state after placing the automatic transmission 20 in the neutral state. This allows the power interrupter 22 to be switched from the engaged state to the disengaged state without transmitting engine friction, which is negative torque, to the power interrupter 22. Therefore, the output torque of the electric motor MG can be smoothly increased when switching from the HEV driving mode to the BEV driving mode.

[0027] The above-described embodiments of the present invention are merely examples, and the present invention can be embodied in various forms with various modifications and improvements based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0028] In the above-described embodiment, the electronic control device 90 reduces the torque on the engine 12 side of the power interrupter 22 by switching the engine 12 to an idling state or by placing the automatic transmission 20 in a neutral state, but the present invention is not limited to this. For example, if the output torque of the engine 12 is reduced compared to the output torque of the engine 12 immediately before the power interrupter 22 is switched from an engaged state to a disengaged state, the engine 12 does not need to be switched to an idling state. Also, if the gear ratio γat of the automatic transmission 20 is lowered compared to the gear ratio γat immediately before the power interrupter 22 is switched from an engaged state to a disengaged state, the automatic transmission 20 does not need to be placed in a neutral state. [Explanation of symbols]

[0029] 10: Hybrid vehicle, 12: Engine, 14: Pair of drive wheels, 20: Automatic transmission, 22: Power interrupt mechanism, 90: Electronic control device (control device), MG: Electric motor, PT: Power transmission path, S: Synchromesh mechanism

Claims

[Claim 1] A control device for a hybrid vehicle having an engine and an electric motor as power sources for driving, in which an automatic transmission, a power interrupter having a synchromesh mechanism, and the electric motor are provided in this order from the engine side on a power transmission path between the engine and a pair of drive wheels, In an HEV driving mode in which the engine is used as a power source, the power interrupter is engaged, In a BEV running mode in which the engine is not used as a power source and the electric motor is used as a power source, the power interrupter is disengaged, When switching from the HEV driving mode to the BEV driving mode, the torque on the engine side of the power interrupter is reduced, and then the power interrupter is switched from the engaged state to the released state. A control device for a hybrid vehicle.

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