Control system of hybrid vehicle

Abstract

To provide a control system of a hybrid vehicle which can perform regenerative power generation when an engine cannot be stopped to perform the regenerative power generation as much as possible.SOLUTION: A control system of a hybrid vehicle comprises: an engine 2 which is connected to driving wheels 11; a clutch 31 which can cut off the connection between the driving wheels 11 and the engine 2; a motor 4 which is connected to the driving wheels 11 when the driving wheels 11 are disconnected with the engine 2 by the clutch 31; and a controller 10 which automatically stops the engine 2 when prescribed automatic stop conditions are satisfied, and cuts off the connection between the driving wheels 11 and the engine 2 through the clutch 31, lets the engine 2 be in a driving state, and performs regenerative brake through the motor 4 when the automatic stop conditions are not satisfied during deceleration of the hybrid vehicle 1.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses that in a parallel hybrid vehicle, during regenerative braking, the engine is always disconnected from the wheels by releasing the clutch to enter the EV regeneration state, and the energy efficiency is improved by eliminating the engine drag. Also, during EV regeneration, the engine is stopped to suppress fuel consumption.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As described in Patent Document 1, when stopping the operation of the engine during EV regeneration, it is conceivable to perform EV regeneration only in a situation where the engine can be automatically stopped.

[0005] However, there are cases where EV regeneration can be performed even when the engine cannot be automatically stopped, and the regenerative power generation cannot be maximized.

[0006] Therefore, an object of the present invention is to provide a control system for a hybrid vehicle that can perform regenerative power generation even when the engine cannot be stopped and can maximize the regenerative power generation.

Means for Solving the Problems

[0007] To solve the above problems, the present invention provides a control system for a hybrid vehicle, comprising: an engine connected to drive wheels; a connection interruption unit capable of interrupting the connection between the drive wheels and the engine; a driving electric motor connected to the drive wheels even when the connection between the drive wheels and the engine is interrupted by the connection interruption unit; and a control unit configured to automatically stop the engine when a predetermined automatic stop condition is satisfied. During deceleration of the hybrid vehicle, when the automatic stop condition is not satisfied, the control unit interrupts the connection between the drive wheels and the engine by the connection interruption unit, brings the engine into a driving state, and performs regenerative braking by the driving electric motor.

Advantages of the Invention

[0008] As described above, according to the present invention, regenerative power generation can be performed even when the engine cannot be stopped, and the regenerative power generation can be maximized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0010] The control system of a hybrid vehicle according to an embodiment of the present invention includes an engine connected to drive wheels, a connection interruption unit capable of interrupting the connection between the drive wheels and the engine, a drive motor connected to the drive wheels even when the drive wheels and the engine are interrupted by the connection interruption unit, and a control unit that automatically stops the engine when a predetermined automatic stop condition is satisfied. The control system of the hybrid vehicle is configured such that, during deceleration of the hybrid vehicle, when the automatic stop condition is not satisfied, the connection interruption unit interrupts the connection between the drive wheels and the engine, places the engine in a driving state, and performs regenerative braking by the drive motor.

[0011] Thereby, the control system of a hybrid vehicle according to an embodiment of the present invention can perform regenerative power generation even in a state where the engine cannot be stopped, and can perform regenerative power generation to the maximum extent.

Example

[0012] Hereinafter, with reference to the drawings, the control system of a hybrid vehicle according to an embodiment of the present invention will be described in detail.

[0013] In FIG. 1, a hybrid vehicle 1 equipped with a control system of a hybrid vehicle according to an embodiment of the present invention includes an engine 2 as an internal combustion engine, a transmission 3, a motor 4 as a drive motor, an inverter 5, a high-voltage battery 6, an air conditioner 7, an ECM (Engine Control Module) 8 that controls the engine 2, a TCM (Transmission Control Module) 9 that controls the transmission 3, and a control unit 10 that comprehensively controls the hybrid vehicle 1.

[0014] The engine 2 has a plurality of cylinders formed therein. In this embodiment, the engine 2 is configured to perform a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke for each cylinder.

[0015] An ISG (Integrated Starter Generator) 21 as an engine starting motor and a starter 22 are connected to the engine 2.

[0016] The ISG 21 is connected to the crankshaft of the engine 2 via a belt (not shown). The ISG 21 has a function of an electric motor that rotationally drives the engine 2 by rotating when power is supplied, and a function of a generator that converts the rotational force input from the crankshaft into electric power.

[0017] In this embodiment, the ISG 21 functions as an electric motor under the control of the ECM 8 to restart the engine 2 from a stopped state by the idling stop function. The ISG 21 can also assist in the running of the hybrid vehicle 1 by functioning as an electric motor.

[0018] The starter 22 includes a motor (not shown) and a pinion gear. The starter 22 rotates the crankshaft of the engine 2 by rotating the motor to apply a starting rotational force to the engine 2. Thus, the engine 2 is started by the starter 22 and restarted by the ISG 21 from a stopped state by the idling stop function.

[0019] Power is supplied to the ISG 21 and the starter 22 from a low-voltage battery 23 as a battery. The low-voltage battery 23 is composed of, for example, a lead-acid battery. The low-voltage battery 23 also supplies power to drive various auxiliary devices such as the electrical system of the hybrid vehicle 1.

[0020] A battery state sensor 23a is provided in the low-voltage battery 23. The battery state sensor 23a detects the charge and discharge current, voltage, and battery temperature of the low-voltage battery 23. The battery state sensor 23a is connected to the control unit 10. The control unit 10 can detect the state of charge (hereinafter referred to as "SOC") of the low-voltage battery 23 based on the output of the battery state sensor 23a.

[0021] The transmission 3 shifts the rotation output from the engine 2 and drives the drive wheels 11 via the drive shaft 12. The transmission 3 includes a constant-mesh transmission mechanism (not shown) composed of a parallel-axis gear mechanism and an actuator (not shown).

[0022] A dry single-plate clutch 31 as a connection cutoff portion is provided between the engine 2 and the transmission 3. The clutch 31 is provided in the power transmission path between the engine 2 and the transmission 3 and connects or cuts off the power transmission path.

[0023] The transmission 3 is configured as a so-called AMT (Automated Manual Transmission), and the shift stage in the transmission mechanism and the engagement and disengagement of the clutch 31 are performed by an actuator (not shown).

[0024] A differential mechanism 32 is provided between the transmission 3 and the drive wheels 11. The differential mechanism 32 and the drive wheels 11 are connected by the drive shaft 12.

[0025] The motor 4 is connected to the differential mechanism 32 via a speed reducer 41 such as a chain. The motor 4 functions as an electric motor. The motor 4 also functions as a generator and generates electricity by the running of the hybrid vehicle 1.

[0026] The inverter 5 converts the three-phase AC power generated by the motor 4 into DC power under the control of the control unit 10. This DC power charges, for example, the high-voltage battery 6.

[0027] The high-voltage battery 6 is composed of, for example, a lithium-ion battery. The high-voltage battery 6 supplies power to the inverter 5.

[0028] The high-voltage battery 6 is provided with a battery state sensor 6a. The battery state sensor 6a detects the charge and discharge current, voltage, and battery temperature of the high-voltage battery 6. The battery state sensor 6a is connected to the control unit 10. The control unit 10 can detect the SOC of the high-voltage battery 6 based on the output of the battery state sensor 6a.

[0029] In this way, the hybrid vehicle 1 constitutes a parallel hybrid system capable of using the power of both the engine 2 and the motor 4 for driving the vehicle, and travels by the power output from at least one of the engine 2 and the motor 4.

[0030] Note that the motor 4 only needs to be connected in a power-transmittable manner to any location in the power transmission path from the engine 2 to the drive wheels 11, and does not necessarily need to be connected to the differential mechanism 32.

[0031] The air conditioner 7 is connected to the control unit 10, and the drive of the air conditioner 7 is controlled by the control unit 10 to perform air conditioning such as heating, cooling, dehumidifying, and ventilation in the vehicle interior.

[0032] The ECM 8, TCM 9, and control unit 10 are each composed of a computer unit including a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory for storing backup data, an input port, and an output port.

[0033] The ROM of these computer units stores programs for causing the computer units to function as the ECM 8, TCM 9, and control unit 10, respectively, together with various constants and various maps.

[0034] That is, by the CPU executing the program stored in the ROM using the RAM as a work area, these computer units function as the ECM8, TCM9, and control unit 10 in the present embodiment, respectively.

[0035] The hybrid vehicle 1 is provided with a CAN communication line 13 for forming an in-vehicle LAN (Local Area Network) compliant with a standard such as CAN (Controller Area Network).

[0036] The ECM8, TCM9, and control unit 10 are respectively connected by the CAN communication line 13. The ECM8, TCM9, and control unit 10 mutually transmit and receive signals such as control signals via the CAN communication line 13.

[0037] Various sensors including an engine speed sensor 93 and a water temperature sensor 94 are connected to the input port of the ECM8. The engine speed sensor 93 detects the engine speed, which is the rotational speed of the engine 2. The water temperature sensor 94 detects the temperature of the cooling water of the engine 2.

[0038] On the other hand, various control targets including an injector (not shown) are connected to the output port of the ECM8. The injector supplies fuel to the engine 2.

[0039] Various control targets including an actuator of the transmission 3 are connected to the output port of the TCM9. The TCM9 controls the actuator of the transmission 3 to switch the gear stage and engage and disengage the clutch 31 in the transmission mechanism of the transmission 3.

[0040] In addition to the above-described battery state sensors 6a and 23a, various sensor switches such as a brake stroke sensor 91, a vehicle speed sensor 92, an outside air temperature sensor 95, a steering angle sensor 96, a control panel 97, and an accelerator opening sensor (not shown) are connected to the input port of the control unit 10.

[0041] The brake stroke sensor 91 detects the amount of depression of a brake pedal (not shown) by the driver. The vehicle speed sensor 92 detects the speed of the hybrid vehicle 1. The outside air temperature sensor 95 detects the temperature of the outside air of the hybrid vehicle 1. The steering angle sensor 96 detects the steering angle of a steering wheel (not shown). The accelerator opening sensor detects the accelerator opening which is the opening of an accelerator pedal (not shown). The control panel 97 receives an operation input of a setting for the air conditioner 7 and outputs the input setting to the control unit 10.

[0042] The control panel 97 is provided with various controllers including, for example, an air introduction mode selection switch for selecting an air inlet for the air blown into the passenger compartment between an outside air inlet and an inside air inlet, an outlet mode selection switch for selecting a combination of ratios of the amounts of air blown out from a defroster outlet, a vent outlet, and a footwell outlet, an air volume adjustment switch for setting the flow rate of the air blown out from these outlets (hereinafter also simply referred to as "blowout amount"), and a temperature setting switch for setting a set temperature.

[0043] On the other hand, various control targets including the above-described inverter 5 are connected to the output port of the control unit 10.

[0044] The control unit 10 calculates a driver required torque required by the driver based on the accelerator opening, vehicle speed, amount of depression of the brake pedal, etc. The control unit 10 calculates a target axle torque as the torque of the drive shaft 12 such that the driver required torque is output to the drive wheels 11, and controls the engine 2 and the motor 4 so as to output the target axle torque to the drive shaft 12.

[0045] The control unit 10 transmits a torque command to the ECM 8 and causes the ECM 8 to output the torque value set in the torque command to the engine 2.

[0046] The control unit 10 calculates the torque to be output to the engine 2 and the torque to be output to the motor 4 based on the target axle torque, the SOC of the high-voltage battery 6, etc.

[0047] Based on the SOC of the high-voltage battery 6, the required torque, etc., the control unit 10 switches between an HEV driving mode in which the driving forces of the engine 2 and the motor 4 are transmitted to the drive shaft 12 to drive the hybrid vehicle 1, and an EV driving mode in which only the driving force of the motor 4 is transmitted to the drive shaft 12 to drive the hybrid vehicle 1.

[0048] For example, when the hybrid vehicle 1 decelerates and satisfies a predetermined automatic stop condition, the control unit 10 stops the engine 2 and switches to the EV driving mode. The automatic stop condition is a condition under which the engine 2 can be restarted after being automatically stopped.

[0049] The automatic stop conditions include, for example, that the SOC of the low-voltage battery 23 is equal to or higher than a predetermined SOC, the temperature of the engine 2 is equal to or higher than a predetermined temperature, the air-conditioning operation requirement can be satisfied even when the engine 2 is stopped, there is no defroster operation requirement from the driver, and the driver's steering requirement can be satisfied even when the engine 2 is stopped. All of these conditions must be met.

[0050] The temperature of the engine 2 is estimated from, for example, the engine coolant temperature, the engine oil temperature, the outside air temperature, etc. Since the engine friction increases as the temperature of the engine 2 decreases, the lowest temperature at which the output torque of the ISG 21 can exceed the engine friction is set as the predetermined temperature.

[0051] Whether the air-conditioning operation requirement can be satisfied even when the engine 2 is stopped is determined, for example, by whether the difference between the air-conditioning temperature set for the passengers of the hybrid vehicle 1 by the control panel 97 and the outside air temperature is equal to or greater than a predetermined temperature difference. When the difference between the air-conditioning temperature set for the passengers and the outside air temperature is equal to or greater than the predetermined temperature difference, it is necessary to operate the compressor of the air-conditioning device 7, so the engine 2 is maintained in the driving state.

[0052] The request for defroster operation from the driver is determined by whether the air outlet mode selection switch on the control panel 97 is set to the defroster air outlet. When the air outlet mode selection switch is set to the defroster air outlet, in order to quickly eliminate the situation where fog blocks the view, the engine 2 is maintained in a driving state as the power source of the air conditioner 7.

[0053] Whether the steering request of the driver can be satisfied even when the engine 2 is stopped is determined by whether the driver is steering. When the driver is steering, in order to assist the steering with a hydraulic pump, the engine 2, which is the power source for hydraulic generation, is maintained in a driving state.

[0054] When the hybrid vehicle 1 decelerates, the control unit 10 performs regenerative braking that outputs regenerative torque to the motor 4 to charge the high-voltage battery 6.

[0055] In this embodiment, when the hybrid vehicle 1 decelerates and does not meet the automatic stop condition, the control unit 10 disconnects the connection between the drive wheels 11 and the engine 2 by the clutch 31, keeps the engine 2 in a driving state, and performs regenerative braking by the motor 4.

[0056] When the hybrid vehicle 1 decelerates and the driver-requested torque is equal to or greater than the outputtable torque of the motor 4, the control unit 10 connects the drive wheels 11 and the engine 2 by the clutch 31.

[0057] Here, the driver-requested torque is, for example, the torque in the deceleration direction obtained from a map based on the vehicle speed and the depression amount of the brake pedal.

[0058] When the driver-requested torque is equal to or greater than the outputtable torque of the motor 4 in the deceleration direction, since the driver-requested torque cannot be realized only by the regenerative braking torque of the motor 4, the clutch 31 is set in the connected state, and deceleration is performed by regenerative braking and engine braking during HEV running.

[0059] When the SOC of the high-voltage battery 6 is greater than a predetermined value and it is determined that the SOC is sufficient and close to full charge, since regenerative braking cannot be performed, as HEV driving, the hybrid vehicle 1 is decelerated only by engine braking.

[0060] Regarding the regenerative control process during deceleration by the control system of the hybrid vehicle according to the present embodiment configured as described above, it will be described with reference to FIG. 2. Note that the regenerative control process during deceleration described below is started when the control unit 10 starts operating and is executed at a preset time interval.

[0061] In step S1, the control unit 10 determines whether the hybrid vehicle 1 is decelerating.

[0062] If it is determined that the vehicle is decelerating, the control unit 10 executes the process of step S2. If it is determined that the vehicle is not decelerating, the control unit 10 ends the regenerative control process during deceleration.

[0063] In step S2, the control unit 10 determines whether the SOC of the high-voltage battery 6 is less than or equal to a predetermined value.

[0064] If it is determined that the SOC of the high-voltage battery 6 is less than or equal to the predetermined value, the control unit 10 executes the process of step S3. If it is determined that the SOC of the high-voltage battery 6 is not less than or equal to the predetermined value, the control unit 10 executes the process of step S8.

[0065] In step S3, the control unit 10 determines whether the driver required torque is less than the outputable torque of the motor 4.

[0066] If it is determined that the driver required torque is less than the outputable torque of the motor 4, the control unit 10 executes the process of step S4. If it is determined that the driver required torque is not less than the outputable torque of the motor 4, the control unit 10 executes the process of step S8.

[0067] In step S4, the control unit 10 determines whether or not the automatic stop of the engine 2 is impossible.

[0068] If it is determined that the automatic stop of the engine 2 is impossible, the control unit 10 executes the process of step S5. If it is determined that the automatic stop of the engine 2 is possible, the control unit 10 executes the process of step S9.

[0069] In step S5, the control unit 10 releases the clutch 31. After executing the process of step S5, the control unit 10 executes the process of step S6.

[0070] In step S6, the control unit 10 sets the engine 2 to the idle state. After executing the process of step S6, the control unit 10 executes the process of step S7.

[0071] In step S7, the control unit 10 outputs a regenerative torque to the motor 4. After executing the process of step S7, the control unit 10 ends the deceleration regenerative control process.

[0072] In step S8, the control unit 10 shifts to HEV running. After executing the process of step S8, the control unit 10 ends the deceleration regenerative control process.

[0073] In step S9, the control unit 10 shifts to EV running. After executing the process of step S9, the control unit 10 ends the deceleration regenerative control process.

[0074] The operation by such deceleration regenerative control process will be described with reference to FIG. 3. During deceleration of the hybrid vehicle 1, when at time t1, it is determined that the SOC of the high-voltage battery 6 is equal to or less than a predetermined value, the driver required torque is equal to or less than the outputable torque of the motor 4, and the automatic stop of the engine 2 is impossible, the release of the clutch 31 is started, the engine 2 is set to the idle state, and a regenerative torque is output by the motor 4.

[0075] During the semi-engagement of the clutch until the release of the clutch 31 is completed, the regenerative torque of the motor 4 is increased in accordance with the decrease in the torque equivalent to the engine brake by the engine 2 during the engagement of the clutch.

[0076] At time t2, when the release of the clutch 31 is completed, a regenerative torque equivalent to the torque equivalent to the engine brake by the engine 2 during the engagement of the clutch is output from the motor 4.

[0077] Thus, in this embodiment, when the hybrid vehicle 1 decelerates and does not satisfy the automatic stop condition, the control unit 10 disconnects the connection between the drive wheels 11 and the engine 2 by the clutch 31, keeps the engine 2 in the driving state, and performs regenerative braking by the motor 4.

[0078] Thereby, even when the engine 2 cannot be stopped during deceleration, regenerative power generation can be performed to the maximum extent.

[0079] Further, the automatic stop condition includes a condition under which the engine 2 can be restarted after the automatic stop of the engine 2.

[0080] Thereby, it is possible to prevent the engine 2 from becoming unable to restart and being unable to run, and even when the engine 2 cannot be stopped during deceleration, regenerative power generation can be performed to the maximum extent.

[0081] Further, the automatic stop condition includes that the SOC of the low-voltage battery 23 is equal to or higher than a predetermined SOC.

[0082] Thereby, it is possible to prevent the engine 2 from becoming unable to restart and being unable to run, and even when the engine 2 cannot be stopped during deceleration because there is insufficient power for using the ISG 21 and the engine restart cannot be guaranteed, regenerative power generation can be performed to the maximum extent.

[0083] Further, the automatic stop condition includes that the temperature of the engine 2 is equal to or higher than a predetermined temperature. This can prevent the engine 2 from being unable to restart and becoming inoperable, and enables maximum regenerative power generation even when the engine 2 cannot be stopped during deceleration when engine friction is high and a large torque is required to start the engine, such as in cold conditions where engine restart cannot be guaranteed.

[0084] Also, the automatic stop condition includes that the air conditioning operation request can be satisfied even when the engine 2 is stopped.

[0085] This can prevent the air conditioning function from being suppressed, and enables maximum regenerative power generation even when the engine 2 cannot be stopped during deceleration.

[0086] Also, the automatic stop condition includes that there is no defroster operation request from the driver. This can prevent the defroster from being suppressed, and enables maximum regenerative power generation even when the engine 2 cannot be stopped during deceleration.

[0087] Also, the automatic stop condition includes that the driver's steering request can be satisfied even when the engine 2 is stopped.

[0088] This can prevent the steering assist from being suppressed, and enables maximum regenerative power generation even when the engine 2 cannot be stopped during deceleration.

[0089] Also, when the vehicle is decelerating and the driver-requested torque is greater than or equal to the output-capable torque of the motor 4, the control unit 10 connects the drive wheels 11 and the engine 2 in a connected state by means of the clutch 31.

[0090] This can apply engine braking to compensate for insufficient braking force, and enables maximum regenerative power generation even when the engine 2 cannot be stopped during deceleration.

[0091] In this embodiment, an example in which the control unit 10 makes various determinations and calculations based on various sensor information has been described. However, the present invention is not limited to this. The hybrid vehicle 1 includes a communication unit capable of communicating with an external device such as an external server. Based on the detection information of various sensors transmitted from the communication unit, various determinations and calculations are performed by the external device, and the determination result and calculation result are received by the communication unit, and various controls may be performed using the received determination result and calculation result.

[0092] Although embodiments of the present invention have been disclosed, it is obvious that those skilled in the art can make changes without departing from the scope of the present invention. It is intended that all such modifications and equivalents be included in the following claims.

Explanation of Signs

[0093] 1 Hybrid vehicle 2 Engine 3 Transmission 4 Motor (drive motor) 6 High-voltage battery 6a Battery state sensor 7 Air conditioner 10 Control unit 11 Driving wheels 12 Drive shaft 21 ISG (starting motor) 23 Low-voltage battery (battery) 23a Battery state sensor 31 Clutch (connection / disconnection unit) 91 Brake stroke sensor 92 Vehicle speed sensor 93 Engine speed sensor 94 Water temperature sensor 95 Outside air temperature sensor 96 Steering angle sensor 97 Control panel

Claims

1. An engine connected to a drive wheel, A connection cut-off part that can cut off the connection between the drive wheel and the engine, A drive motor connected to the drive wheel even when the drive wheel and the engine are cut off by the connection cut-off part, A control system for a hybrid vehicle comprising a control unit that automatically stops the engine when a predetermined automatic stop condition is satisfied, wherein The control unit cuts off the connection between the drive wheel and the engine by the connection cut-off part when the automatic stop condition is not satisfied during deceleration of the hybrid vehicle, puts the engine in a driving state, and performs regenerative braking by the drive motor. A control system for a hybrid vehicle.

2. The control system for a hybrid vehicle according to claim 1, wherein the automatic stop condition includes a condition under which the engine can be restarted after the automatic stop of the engine.

3. An engine starting motor for starting the engine, Having a battery that supplies power to the engine starting motor, The control system for a hybrid vehicle according to claim 2, wherein the automatic stop condition includes that the SOC of the battery is equal to or higher than a predetermined SOC.

4. The control system for a hybrid vehicle according to claim 2 or claim 3, wherein the automatic stop condition includes that the temperature of the engine is equal to or higher than a predetermined temperature.

5. The control system for a hybrid vehicle according to claim 1, wherein the automatic stop condition includes that an air conditioning operation request can be satisfied even when the engine is stopped.

6. The control system for a hybrid vehicle according to claim 5, wherein the automatic stop condition includes that there is no defroster operation request from the driver.

7. The control system for a hybrid vehicle according to claim 1, wherein the automatic stop condition includes that a driver's steering request can be satisfied even when the engine is stopped.

8. The control system for a hybrid vehicle according to claim 1, wherein the control unit connects the drive wheel and the engine in a connected state by the connection cut-off part when the driver request torque is equal to or higher than the outputable torque of the drive motor.

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