Control device for hybrid vehicle

Abstract

The present invention provides a control device for a hybrid vehicle capable of smoothly switching a driving mode accompanying engine start in a hybrid vehicle. The control device for the hybrid vehicle comprises a mode switching control unit for performing mode switching control for switching from a first driving mode in which the engine is stopped and the driving wheels are driven by the power generated by an electric motor to a second driving mode in which the driving wheels are driven by the power generated by the engine and the electric motor according to a prescribed mode switching demand; the mode switching control unit comprises a clutch control unit; the clutch control unit starts the engine by using the rotation of the transmission shaft by making the clutch in a semi-clutch state when receiving the mode switching demand, and when the engine is determined to have been started, temporarily converts the clutch from the semi-clutch state to a standby state in which the driving force of the engine is not transmitted and the clutch is then converted to a connected state.

Description

Technical Field

[0001] The present disclosure relates to a control device for a hybrid vehicle including an engine and an electric motor as driving sources for traveling.

[0002] A hybrid vehicle having an engine and an electric motor as driving sources is known. The hybrid vehicle travels by switching between a driving mode (a first driving mode) in which the electric motor is driven while the engine is stopped and a driving mode (a second driving mode) in which both the engine and the electric motor are driven, depending on the remaining battery level.

[0003] In order to switch from the first driving mode in which the engine is stopped to the second driving mode in which the engine needs to be driven, the engine must be started. In the conventional starting method using some starter motors, there are problems such as requiring a larger battery than before depending on the frequency of use or having a shorter life of the starter motor.

[0004] On the other hand, there is also a method of starting the engine by utilizing the inertia of the vehicle caused by the driving force of the electric motor (that is, starting the vehicle by pushing the vehicle) (see Patent Document 1 below, etc.). The method of starting the engine by pushing the vehicle does not require a starter motor, so it can be considered to be applicable as a method of switching the driving mode accompanying the start of the engine.

[0005] Prior art literature:

[0006] Patent Literature

[0007] Patent document 1: Japanese Patent Application Publication No. 2017-65384. Summary of the invention

[0008] Problems to be solved by the invention:

[0009] However, in the above-mentioned push-start, when the clutch for transmitting the driving force of the engine to a predetermined transmission shaft (e.g., the input shaft of a transmission) rotated by the driving force of the electric motor is simply switched from the disconnected state to the engaged state, the sudden increase in the engine torque after the engine is started may cause a sudden increase in the rotation speed of the transmission shaft, and there is a problem that the first driving mode cannot be smoothly switched to the second driving mode. Such a problem is particularly prominent in a vehicle with a small inertia such as a motorcycle.

[0010] Patent Document 1 discloses a control for changing the movement speed of the clutch according to the position of the clutch. However, the control of Patent Document 1 cannot sufficiently suppress a sudden increase in the rotation speed of the transmission shaft caused by the clutch being engaged.

[0011] The present disclosure aims to provide a control device for a hybrid vehicle that can smoothly switch the driving mode when the engine is started.

[0012] Means of solving the problem:

[0013] According to one form of the present disclosure, a control device for a hybrid vehicle includes an electric motor and an engine as driving sources for driving, a transmission shaft for transmitting the driving force of the electric motor to driving wheels, and a clutch for switching whether to transmit the driving force of the engine to the transmission shaft; the control device for the hybrid vehicle is provided with a mode switching control unit, and the mode switching control unit performs mode switching control for switching from a first driving mode in which the engine is stopped and the driving wheels are driven by the power generated by the electric motor to a second driving mode in which the driving wheels are driven by the power generated by the engine and the electric motor according to a prescribed mode switching requirement; the mode switching control unit includes a control unit for causing the clutch to transmit the driving force of the engine to the transmission shaft when the clutch does not transmit the driving force of the engine to the transmission shaft A clutch control unit for switching between a disconnected state and an engaged state in which the engine is transmitted to the transmission shaft; the clutch control unit controls as follows: when the mode switching request is received, the engine is started by utilizing the rotation of the transmission shaft by making the clutch a semi-clutch state, wherein the semi-clutch state is a state between the disconnected state and the engaged state and the driving force of the engine is transmitted to the transmission shaft; when the engine is determined to have been started, the clutch is temporarily converted from the semi-clutch state to a standby state, and then the clutch is converted to the engaged state, wherein the standby state is a state between the semi-clutch state and the disconnected state and the driving force of the engine is not transmitted to the transmission shaft.

[0014] According to the above structure, when the first driving mode in which the driving wheels are driven by the power generated by the electric motor is changed to the second driving mode in which the driving wheels are driven by the power generated by the engine and the electric motor, the clutch is put into a semi-clutch state, and after the engine is started by the rotation of the transmission shaft, the clutch is switched to a standby state, which is a state in which the driving force of the engine is not transmitted. Therefore, the surge in the rotation speed of the transmission shaft after the engine is started due to the surge in the engine torque can be suppressed. Therefore, the switching from the first driving mode to the second driving mode accompanying the engine start can be smoothly performed.

[0015] The clutch control unit may also be controlled as follows: when the mode switching request is received, the pressure of the actuator used to actuate the clutch is set to a third pressure between a first pressure corresponding to the disconnected state and a second pressure corresponding to the engaged state that is higher than the first pressure; when the engine is determined to have been started, the pressure of the actuator is temporarily changed from the third pressure to a fourth pressure between the first pressure and the third pressure, and then to the second pressure.

[0016] According to the above configuration, the state transition of the clutch can be easily controlled by changing the pressure of the actuator.

[0017] The mode switching control unit may include a throttle opening control unit that controls a throttle opening of the engine; and the throttle opening control unit sets the throttle opening to an opening greater than a reference opening when the clutch is in the half-clutch state.

[0018] According to the above configuration, the clutch is placed in a semi-clutch state to reduce pumping loss generated when the engine is started by the rotation of the transmission shaft due to the drive of the electric motor, so that the engine can be easily started.

[0019] The mode switching control unit may also include: a transmission shaft torque estimating unit that estimates the torque of the transmission shaft; a load torque estimating unit that estimates the load torque applied to the hybrid vehicle; and a motor output control unit that performs output control of the electric motor; the motor output control unit estimates the engine loss torque of the electric motor that is the driving force consumed when the engine is started when the clutch is in the semi-clutch state based on the torque of the transmission shaft and the load torque, and adds the amount of the engine loss torque to the required torque of the electric motor.

[0020] According to the above structure, when the engine is started by rotating the transmission shaft driven by the electric motor by setting the clutch to a semi-clutch state, the electric motor rotates with a torque equal to the required torque plus the estimated engine loss torque, thereby suppressing the decrease in the rotation speed of the transmission shaft when the engine is started. Therefore, the influence on the vehicle stability can be reduced.

[0021] The mode switching control unit may also include an engine speed control unit that controls the speed of the engine; the engine speed control unit performs speed synchronization control to make the speed of the transmission shaft accompanied by the rotation of the engine consistent with the speed of the transmission shaft accompanied by the rotation of the electric motor when the clutch is in a standby state; the clutch control unit switches the clutch to the engaged state through the speed synchronization control when the difference between the speed of the transmission shaft accompanied by the rotation of the engine and the speed of the transmission shaft accompanied by the rotation of the electric motor is within a prescribed reference value.

[0022] According to the above structure, after the engine is started, while the clutch is in a standby state where the driving force of the engine is not transmitted, the engine speed is adjusted to be synchronized with the speed of the transmission shaft accompanying the rotation of the electric motor, thereby suppressing the decrease in the speed of the transmission shaft when the clutch is engaged. Therefore, the switching from the first driving mode to the second driving mode accompanying the engine start can be performed smoothly and in a short time.

[0023] The mode switching control unit may also include a required torque distribution unit that obtains the required torque and distributes the required torque to the electric motor and the engine; after the clutch is changed to the engaged state, the required torque distribution unit performs tracking control to gradually transition from the distribution state of the required torque of the first driving mode to the distribution state of the required torque of the second driving mode.

[0024] According to the above configuration, the torque fluctuation of the entire vehicle after the engine is started can be suppressed by gradually distributing the required torque only from the electric motor 3 to the engine 2. Therefore, the switching from the first driving mode to the second driving mode with the engine started can be smoothly performed.

[0025] The standby state may be set to a state without gap with respect to the half-clutch state.

[0026] According to the above configuration, the clutch can be switched from the standby state to the engaged state for transmitting the driving force of the engine in a short time. Therefore, the switching from the first driving mode to the second driving mode accompanying the engine start can be performed smoothly and in a short time.

[0027] When the clutch control unit receives the mode switching request while the vehicle is traveling, the clutch control unit may start the engine by utilizing the drive of the electric motor or the rotation of the transmission shaft caused by the inertia of the vehicle by placing the clutch in the semi-clutch state.

[0028] The hybrid vehicle may be a motorcycle.

[0029] Effect of the invention:

[0030] According to the present disclosure, it is possible to smoothly switch the running mode accompanying the start of the engine in a hybrid vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a block diagram of a hybrid vehicle according to an embodiment;

[0032] Figure 2 yes Figure 1 A state transition diagram of each driving mode of the hybrid vehicle shown;

[0033] Figure 3 yes Figure 1 A block diagram of a control device for a hybrid vehicle shown;

[0034] Figure 4 is a flowchart showing the flow of a process for switching control from the EV mode to the HEV mode in the present embodiment;

[0035] Figure 5 It is shown Figure 4 A graph showing the time variation of the values ​​in the switching control shown;

[0036] Figure 6 It is shown Figure 3 A block diagram of a motor target torque correction function of a motor torque control unit shown;

[0037] Explanation of symbols:

[0038] 1. Hybrid vehicles;

[0039] 2 engines;

[0040] 3. Electric motor;

[0041] 5 Clutch;

[0042] 8 driving wheels;

[0043] 20. Control device;

[0044] 24 demand torque distribution unit;

[0045] 25 mode switching control unit;

[0046] 28 Engine speed control unit;

[0047] 29 throttle opening control unit;

[0048] 30 Clutch control unit;

[0049] 31 transmission shaft torque estimation unit;

[0050] 32 load torque estimation unit;

[0051] 33 Motor output control unit. DETAILED DESCRIPTION

[0052] Hereinafter, embodiments will be described with reference to the drawings.

[0053] Figure 1 1 is a block diagram of a hybrid vehicle 1 according to an embodiment. In this embodiment, the hybrid vehicle 1 is a two-wheeled motor vehicle having rear wheels as driving wheels 8 and front wheels (not shown) as driven wheels. The two-wheeled motor vehicle is a preferred example of a leaning vehicle that turns while tilting the vehicle body to the left or right. The hybrid vehicle 1 may be a three-wheeled vehicle or a four-wheeled vehicle.

[0054] The hybrid vehicle 1 includes an electric motor 3 and an engine 2 , a transmission shaft (an input shaft 4 a of a transmission 4 described later) for transmitting the driving force of the electric motor 3 to drive wheels 8 , and a clutch 5 for switching whether the driving force of the engine 2 is transmitted to the transmission shaft.

[0055] In more detail, Figure 1 As shown, hybrid vehicle 1 includes engine 2 , electric motor 3 , transmission 4 , clutch 5 , clutch actuator 6 , output transmission member 7 , drive wheels 8 , high voltage battery 9 , charging port 10 , converter 12 , low voltage battery 13 , and control device 20 .

[0056] The engine 2 is an internal combustion engine. The engine 2 is a driving source for driving the driving wheel 8. The electric motor 3 is a driving source for driving the driving wheel 8 together with the engine 2 or in place of the engine 2. The transmission 4 changes the speed of the rotational power output from the engine 2. The transmission 4 is, for example, a manual transmission having an input shaft 4a, an output shaft 4b, and a speed change gear. In the present embodiment, the transmission shaft is configured as the input shaft 4a of the transmission 4.

[0057] The clutch 5 engages and disengages the power transmission between the engine 2 and the transmission 4. The clutch actuator 6 drives the clutch 5 in a manner that switches the clutch 5 between the engaged state and the disengaged state. The output transmission member 7 is a member that transmits the rotational power output from the output shaft 4b of the transmission 4 to the drive wheel 8. The output transmission member 7 is, for example, a drive chain, a drive belt, a drive shaft, etc.

[0058] The high-voltage battery 9 stores high-voltage electricity (e.g., 48V) supplied to the electric motor 3. The high-voltage battery 9 is connected to a charging port 10. The converter 12 steps down the voltage of the direct current from the high-voltage battery 9 and supplies it to the low-voltage battery 13. The low-voltage battery 13 stores low-voltage electricity (e.g., 12V) supplied to the control device 20 and other low-voltage loads 14 mounted on the hybrid vehicle 1.

[0059] The control device 20 controls the engine 2, the electric motor 3, and the actuator (clutch actuator) 6 based on information from various sensors. The control device 20 may be a single controller or may be distributed as a plurality of controllers. The control device 20 includes a processor, a volatile memory, a nonvolatile memory, and an I / O interface in terms of hardware. The details of the functions of the control device 20 will be described later.

[0060] Figure 2 yes Figure 1 The state transition diagram of each driving mode of the hybrid vehicle is shown in FIG. Figure 2 As shown, the hybrid vehicle 1 has a plurality of driving modes in which at least one of the engine 2, the electric motor 3 and the clutch 5 is in a different state. Specifically, the driving modes include an EV mode (first driving mode), an HEV mode (second driving mode) and a transition mode.

[0061] The EV mode (first driving mode) is a mode in which the engine 2 is stopped and the driving wheels 8 are driven by the power generated by the electric motor 3. In the EV mode, the clutch 5 is in a disengaged state so that the engine 2 does not serve as resistance when the electric motor 3 is driving. In the EV mode, the electric motor 3 is in a driving state during acceleration and in a regenerative state during deceleration.

[0062] The HEV mode (second driving mode) is a mode in which the driving wheels 8 are driven by the power generated by the electric motor 3 and the engine 2. In the HEV mode, the clutch 5 is engaged in the form of the rotational power of the engine 2 being transmitted to the driving wheels 8 via the transmission 4. In the HEV mode, the electric motor 3 is in the driving state during acceleration driving, and the electric motor 3 is in the regenerative state during deceleration driving. The transition mode is a switching control mode during the transition from the EV mode to the HEV mode.

[0063] In addition, there is a transition state in which the clutch 5 is disengaged and the engine 2 is stopped during the transition from the HEV mode to the EV mode. Figure 2 Although not shown, the travel mode of the hybrid vehicle 1 may include an EGV mode (engine vehicle mode) in which the engine 2 is driven without driving the electric motor 3 and the drive wheels 8 are driven only by the rotational power of the engine 2 .

[0064] Figure 3 yes Figure 1 FIG. 2 is a block diagram of a control device 20 for a hybrid vehicle 1. Figure 3 As shown, the control device 20 includes a required torque calculation unit 21, a required torque mediation unit 22, a mode switching requirement generation unit 23, a required torque distribution unit 24, and a mode switching control unit 25. Each unit 21 to 25 of the control device 20 is configured as a functional block that is realized by a processor performing calculation processing using a volatile memory based on a program stored in a non-volatile memory.

[0065] The required torque calculation unit 21 calculates various required torques corresponding to the running state of the hybrid vehicle 1 based on the accelerator opening, vehicle body posture, SOC (State Of Charge), vehicle speed, engine speed, motor speed, etc. For example, the various required torques include user (rider) required torque, vehicle body control required torque, charging required torque, power unit protection required torque, and emergency required torque.

[0066] The user demand torque is a torque calculated based on the output state desired by the user from the accelerator opening, etc. The accelerator opening means the amount of accelerator operation by the user, and can be obtained from the output of an accelerator opening sensor.

[0067] The vehicle body control required torque is a torque required when viewed from the vehicle body side, such as rollover suppression control, based on the vehicle body posture, vehicle speed, engine speed, and motor speed, regardless of the degree of accelerator operation by the user. The vehicle speed is calculated from, for example, the detection value of a speed sensor of a driven wheel (for example, a front wheel), but can also be calculated from GPS information, etc. The motor speed is calculated from, for example, the detection value of a speed sensor provided on the rotating shaft of the electric motor 3, but can also be calculated from the control signal of the electric motor 3. The engine speed can be calculated from the output of a crank angle sensor that detects the crank angle of the crankshaft of the engine 2.

[0068] The vehicle body posture includes at least one of the roll angle, pitch angle, slip rate, steering angle, direction indicator information, vehicle position information, and front camera information. The roll angle and pitch angle are calculated based on the detection values ​​of a gyro sensor mounted on the vehicle, for example, but can also be calculated from the detection values ​​of a roll angle sensor and a pitch angle sensor. The pitch angle can also be calculated from the stroke of the front suspension and the rear suspension.

[0069] The slip ratio is calculated, for example, by the formula (driving wheel speed - driven wheel speed) / driven wheel speed, but may also be the rate of increase of the driving wheel speed, etc. The steering angle is calculated, for example, by the detection value of the steering angle sensor. The direction indicator information is obtained as the indicator action information of the left turn or the right turn based on the signal of the user operating the direction indicator. The vehicle position information is information showing where the hybrid vehicle 1 is traveling on the map based on the detection value of the GPS sensor and the map information. The front camera information is image information obtained by the vehicle-mounted camera that captures the front of the hybrid vehicle 1.

[0070] The charging demand torque is a torque calculated to make the electric motor 3 generate electricity and charge the high-voltage battery 9 according to the SOC (%) indicating the state of charge of the high-voltage battery 9. That is, the demand torque calculation unit 21 calculates the power generation torque of the electric motor 3 required to charge the high-voltage battery 9 as the charging demand torque after the remaining amount of the high-voltage battery 9 decreases. The SOC can be calculated from the output of the battery remaining amount sensor.

[0071] The power unit protection required torque is a torque calculated from the engine speed and the motor speed, etc., in order to protect the engine 2 and the electric motor 3 from overheating, etc. The emergency required torque is a torque calculated in an emergency such as when a rollover occurs.

[0072] The required torque mediation unit 22 calculates the torque that the traveling drive sources (the engine 2 and the electric motor 3 ) should output as a total required torque based on the priorities of the various required torques calculated by the required torque calculation unit 21 .

[0073] The mode switching demand generating unit 23 determines the optimal driving mode from the above-mentioned multiple driving modes based on the total required torque, vehicle speed, transmission shaft speed (speed of the input shaft 4a of the transmission 4) and motor output torque after understanding the current driving state. In addition, the transmission shaft speed is calculated from the detection value of the speed sensor provided on the input shaft 4a. The mode switching demand generating unit 23 generates a mode switching demand for switching the driving mode when the current driving mode and the determined driving mode are different.

[0074] Furthermore, the mode switching demand generating unit 23 distributes the total required torque to the electric motor 3 and the engine 2 according to the determined driving mode. Therefore, the mode switching demand generating unit 23 includes a required torque distributing unit 24. The required torque distributing unit 24 determines and outputs the target torque (engine target torque) to be output by the engine 2 and the target torque (motor target torque) to be output by the electric motor 3 according to the determined driving mode and the total required torque.

[0075] The mode switching control unit 25 switches between the EV mode and the HEV mode according to the mode switching demand, and controls the engine 2 and the electric motor 3 according to the target torques corresponding to the respective driving modes after the switching. In the control of the engine 2, the mode switching control unit 25 controls the throttle opening of the engine 2 based on the engine speed in addition to the target torque. For such control, the mode switching control unit 25 includes a motor torque control unit (motor control unit) 26, an engine torque control unit 27, an engine speed control unit 28, a throttle opening control unit 29, and a clutch control unit 30.

[0076] The motor torque control unit 26 sends an inverter command value to (the inverter of) the electric motor 3 based on the motor target torque output from the mode switching request generation unit 23 to drive the electric motor 3 so that the output torque of the electric motor 3 becomes the motor target torque.

[0077] The engine torque control unit 27 determines the target value of the throttle opening (first throttle target opening) based on the engine target torque and the engine speed output from the mode switching demand generating unit 23. The engine speed control unit 28 determines the target value of the throttle opening (second throttle target opening) such that the engine speed and the motor speed are synchronized based on the engine speed and the motor speed. The throttle opening control unit 29 determines the final throttle opening command value output to the engine 2 based on the first throttle target opening and the second throttle target opening. In addition, the control device 20 outputs a fuel injection signal corresponding to the throttle opening command value to the fuel injection device of the engine 2, and outputs an engine ignition signal to the ignition device of the engine 2.

[0078] The clutch control unit 30 outputs a clutch position command value for switching the clutch 5 between a disconnected state in which the driving force of the engine 2 is not transmitted to the input shaft (transmission shaft) 4a of the transmission 4 and a connected state in which the driving force of the engine 2 is transmitted to the input shaft (transmission shaft) 4a to the clutch actuator 6 according to the mode switching demand. In the present embodiment, the clutch position command value includes a disconnected position in which the clutch 5 is disconnected and a connected position in which the clutch 5 is connected, as well as a command value for placing the clutch 5 in a half-clutch position and a standby position described later as a control position (stop position) of the clutch 5.

[0079] Hereinafter, a description will be given of a flow of processing when the traveling mode is switched from the EV mode to the HEV mode. Figure 4 : is a flowchart showing the flow of the process of switching control from EV mode to HEV mode in this embodiment. Figure 5 It is shown Figure 4 A graph showing the time variation of the values ​​in the switching control.

[0080] Figure 5 The following are shown in order from the top: a graph showing target torques of the engine 2 and the electric motor 3, a graph showing the rotation speeds of the engine 2 and the electric motor 3, a graph showing the position of the clutch 5, a graph showing the pressure (clutch pressure) generated by the actuator 6 of the clutch 5, and a graph showing the throttle opening. Figure 5 In the graph of , each target torque and each rotation speed are converted values ​​of each target torque and each rotation speed in the transmission shaft (the input shaft 4 a of the transmission 4 ).

[0081] As described above, in the EV mode, the clutch 5 is in the disengaged state, and the driving wheels 8 are driven by the power generated by the electric motor 3. When the mode switching request generating unit 23 determines to switch to the HEV mode during the travel of the hybrid vehicle 1 in the EV mode, it outputs a mode switching request from the EV mode to the HEV mode to the clutch control unit 30 (step S1).

[0082] When receiving the mode switching request, the clutch control unit 30 changes the clutch 5 from the disconnected state to the semi-clutch state, thereby starting the engine 2 by rotating the transmission shaft (the input shaft 4a of the transmission 4), and performing a so-called push start (step S2). The semi-clutch state of the clutch 5 is a state between the disconnected state and the engaged state, and the driving force of the engine 2 is transmitted to the input shaft 4a. Figure 5 As shown, the clutch position in the semi-clutch state and the clutch position in the coupled state are almost unchanged in this embodiment. However, in the semi-clutch state, the clutch pressure is a pressure lower than the clutch pressure in the coupled state.

[0083] That is, when the clutch control unit 30 receives the above-mentioned mode switching request, it changes the pressure of the actuator 6 for actuating the clutch 5 from the first pressure P1 corresponding to the disconnected state to the third pressure P3 between the first pressure and the second pressure higher than the first pressure corresponding to the engaged state. In this way, the state transition of the clutch 5 can be easily controlled by changing the pressure of the actuator 6.

[0084] During EV mode driving, the clutch 5 is in a semi-clutch state, whereby the rotational power of the input shaft 4a caused by the drive of the electric motor 3 or the inertia of the hybrid vehicle 1 (rotation of the drive wheels 8) is transmitted to the crankshaft of the engine 2, and the engine 2 is started by the crankshaft rotation.

[0085] In the present embodiment, the throttle opening degree control and the electric motor 3 are additionally controlled when the push cart is started.

[0086] More specifically, when the clutch 5 is in the semi-clutch state, the throttle opening control unit 29 makes the throttle opening be an opening greater than the reference opening (step S3). In the present embodiment, the opening (command value) greater than the reference opening is set as full opening (throttle opening 100%). Furthermore, when the throttle opening control unit 29 receives the above-mentioned mode switching request, it increases the throttle opening in parallel with the operation of the clutch 5.

[0087] In addition, the opening degree above the reference opening degree may not necessarily be fully opened. For example, the reference opening degree may be set to a predetermined opening degree greater than the opening degree at idling, and the throttle opening degree may be controlled to an opening degree above this reference opening degree.

[0088] The motor torque control unit 26 estimates the engine loss torque of the electric motor 3 which is the driving force consumed by the engine 2 when starting the cart, and corrects the motor target torque by adding the engine loss torque to the motor required torque of the electric motor 3 (step S4 ).

[0089] Figure 6 It is shown Figure 3 The block diagram of the motor target torque correction function of the motor torque control unit is shown in FIG. Figure 6 As shown, the motor torque control unit 26 includes a transmission shaft torque estimating unit 31 , a load torque estimating unit 32 , and a motor output control unit 33 in order to execute a correction function of the motor target torque.

[0090] The transmission shaft torque estimation unit 31 obtains the rotation speed (transmission shaft rotation speed) of the input shaft 4a of the transmission 4 as the transmission shaft, and estimates the torque (transmission shaft total torque) generated by the input shaft 4a from the rotation speed change. In the semi-clutch state and the engaged state of the clutch 5, the transmission shaft total torque includes the increase and decrease of the torque generated by the connection between the engine 2 and the input shaft 4a. The load torque estimation unit 32 obtains the vehicle speed, calculates the load torque of the drive shaft of the drive wheel 8 from the vehicle speed change, and converts the load torque of the drive shaft into the load torque of the transmission shaft. The load torque is obtained by converting the driving resistance such as air resistance into the torque of the drive shaft, and the driving resistance is larger when the vehicle speed is larger. Therefore, the load torque is also larger when the vehicle speed is larger.

[0091] The motor output control unit 33 converts the motor target torque into an inverter command value to control the output of the electric motor 3. The motor output control unit 33 obtains the motor target torque (target torque before correction) from the mode switching demand generation unit 23. In addition, the motor output control unit 33 obtains the total torque of the transmission shaft from the transmission shaft torque estimation unit 31 and obtains the load torque from the load torque estimation unit 32. Furthermore, the motor output control unit 33 obtains the motor output torque and converts it into the motor output torque of the transmission shaft.

[0092] The motor output control unit 33 deducts the total torque of the transmission shaft from the motor output torque of the transmission shaft to calculate the torque amount lost by the transmission shaft due to the engine 2. In the present embodiment, the motor output control unit 33 further determines the value obtained by deducting the load torque from the value as the estimated engine loss torque of the transmission shaft. The engine loss torque is an estimated value of the driving force of the electric motor 3 consumed when the engine 2 is started when the clutch 5 is in a semi-clutch state. The motor output control unit 33 converts the engine loss torque of the transmission shaft into the engine loss torque of the output shaft of the electric motor 3.

[0093] The motor output control unit 33 corrects the motor target torque by adding the obtained engine loss torque (the value of the output shaft of the electric motor 3) to the motor target torque (the value of the output shaft of the electric motor 3) output from the mode switching demand generating unit 23. That is, the motor output control unit 33 adds the estimated amount of the engine loss torque to the demand torque of the electric motor 3 (the motor target torque before correction). Thus, the motor target torque is corrected in such a way that the greater the influence of the push start of the engine 2 on the transmission shaft torque, the greater the motor target torque.

[0094] In addition, in the present embodiment, as described above, although the difference between the total torque of the transmission shaft and the motor output torque plus the value of the load torque is taken as the engine loss torque, the load torque may not be included in the engine loss torque. In this case, the effect of the load torque may be added to the target torque of other motors and a correction corresponding to the load torque may be performed before and after the correction of the engine loss torque.

[0095] The motor output control unit 33 converts the corrected motor target torque into an inverter command value and outputs the resultant value. The electric motor 3 is inverter-controlled based on the inverter command value, and its output (torque) is controlled.

[0096] The clutch control unit 30 determines whether the engine 2 has started (step S5 ). The clutch control unit 30 determines that the engine 2 has started when the engine speed is equal to or greater than a predetermined starting reference value.

[0097] When the clutch control unit 30 determines that the engine 2 has started (Yes in step S5), it temporarily switches the clutch 5 from the semi-clutch state to the standby state (step S6). The standby state is a state between the semi-clutch state and the disconnected state, and is a state in which the driving force of the engine 2 is not transmitted to the transmission shaft (input shaft 4a).

[0098] like Figure 5As shown, in this embodiment, the clutch position in the standby state is located at a position close to the clutch position in the engaged state. However, in the standby state, the clutch pressure is a pressure lower than the clutch pressure in the semi-clutch state. That is, when the clutch control unit 30 determines that the engine 2 is started by push, the pressure of the actuator 6 is temporarily changed from the third pressure P3 to the fourth pressure P4 between the first pressure P1 and the third pressure P3. The standby state is set to a state without gaps relative to the semi-clutch state (a state that can be immediately changed to the semi-clutch state and the engaged state).

[0099] When the clutch 5 is in the standby state, the engine speed control unit 28 performs speed synchronization control to make the transmission shaft speed accompanying the rotation of the engine 2 (the transmission shaft conversion value of the engine speed) and the transmission shaft speed accompanying the rotation of the electric motor 3 (the transmission shaft conversion value of the motor speed) consistent (step S7). The engine speed control unit 28 sets and outputs the second throttle valve target opening so that the engine speed is equal to the motor speed. In conjunction with this, the throttle valve opening control unit 29 outputs a throttle valve opening command value corresponding to the second throttle valve target opening. The throttle valve opening control unit 29 is composed of a PID controller, and the throttle valve opening is controlled by PID.

[0100] In the speed synchronization control, the engine speed control unit 28 may control not only the throttle opening but also the fuel injection amount or the ignition timing.

[0101] The clutch control unit 30 determines whether the transmission shaft speed accompanying the rotation of the engine 2 is synchronized with the transmission shaft speed accompanying the rotation of the electric motor 3 (step S8). More specifically, the clutch control unit 30 determines whether the difference between the transmission shaft conversion value of the engine speed and the transmission shaft conversion value of the motor speed is within a predetermined synchronization reference value.

[0102] When the transmission shaft rotation speed is determined to be synchronized (Yes in step S8), the clutch control unit 30 switches the clutch 5 to the engaged state (step S9). That is, when the transmission shaft rotation speed is determined to be synchronized, the clutch control unit 30 changes the pressure of the actuator 6 from the fourth pressure to the second pressure.

[0103] After the clutch 5 is switched to the engaged state, the required torque distribution unit 24 performs tracking control to gradually switch from the distribution state of the required torque in the EV mode to the distribution state of the required torque in the HEV mode (step S10). For example, the required torque distribution unit 24 determines that the clutch 5 is switched to the engaged state when the difference between the transmission shaft conversion value of the engine speed and the transmission shaft conversion value of the motor speed is within a predetermined synchronization reference value.

[0104] In the present embodiment, in the EV mode, since the engine 2 is stopped, the electric motor 3 bears 100% of the total required torque. On the other hand, in the HEV mode, 100% of the total required torque is borne by the engine 2 in a steady state. When the torque generated by the engine 2 is insufficient with respect to the total required torque, the electric motor 3 generates torque in a complementary manner.

[0105] Therefore, in this embodiment, when switching from EV mode to HEV mode, the motor target torque is changed from 100% to approximately 0% of the total required torque, and the engine target torque is changed from 0% to approximately 100% of the total required torque. The required torque allocating unit 24 performs tracking control to smoothly change these target torques. Figure 5 In the example of FIG. 1 , a linear change of each target torque is illustrated as the following control, but a nonlinear change may be performed within a range in which the target torque changes gradually.

[0106] According to the above structure, when changing from the first driving mode (EV mode) in which the driving wheel 8 is driven by the power generated by the electric motor 3 to the second driving mode (HEV mode) in which the driving wheel 8 is driven by the power generated by the engine 2 and the electric motor 3, the clutch 5 is placed in a semi-clutch state, and after the engine 2 is started by the rotation of the transmission shaft (the input shaft 4a of the transmission 4), the clutch 5 is switched to a standby state, which is a state in which the driving force of the engine 2 is not transmitted.

[0107] After starting the engine 2 by pushing the cart, if the clutch 5 is directly changed from the semi-clutch state to the engaged state, the transmission shaft rotation speed may increase rapidly. In particular, in the case of a two-wheeled motor vehicle, the output torque per cylinder of the engine 2 is larger than that of a four-wheeled vehicle, and there is a tendency for the transmission shaft rotation speed to increase rapidly.

[0108] Therefore, by temporarily switching the clutch 5 from the semi-clutch state to the standby state, the sudden increase in the rotation speed of the transmission shaft after the engine is started due to the sudden increase in engine torque can be suppressed, and the vehicle body can be stabilized. Therefore, the switch from the first driving mode to the second driving mode accompanying the engine start can be smoothly performed.

[0109] Furthermore, since the standby state of the clutch 5 is set to a state without gaps relative to the semi-clutch state, the clutch 5 can be switched from the standby state to the engaged state for transmitting the driving force of the engine 2 in a short time. Therefore, the switching from the first driving mode to the second driving mode accompanied by the engine starting can be performed smoothly and in a short time.

[0110] Furthermore, according to the above structure, when the clutch 5 is in the semi-clutch state, the throttle opening is an opening greater than the reference opening. Therefore, the pumping loss generated when the engine 2 is started by the rotation of the transmission shaft driven by the electric motor 3 is reduced by setting the clutch 5 in the semi-clutch state, so that the engine 2 can be easily started.

[0111] According to the above configuration, when the engine 2 is started by rotating the transmission shaft driven by the electric motor 3 by half-engaging the clutch 5, the electric motor 3 rotates with a torque obtained by adding the estimated engine loss torque to the required torque.

[0112] The engine loss torque generated when the engine 2 is started by pushing the vehicle may cause the motor speed to drop sharply, which may affect the stability of the hybrid vehicle 1. In particular, in the case of a two-wheeled motor vehicle, the inertia is smaller than that of a four-wheeled vehicle, so the increase in the rotational resistance of the transmission shaft caused by the contact with the transmission shaft of the clutch 5 has a greater impact on the decrease in the motor speed. Therefore, by performing the torque control of the electric motor 3 such that the amount of the engine loss torque is added as described above, the decrease in the speed of the transmission shaft when the engine 2 is started can be suppressed. Therefore, the influence on the stability of the hybrid vehicle 1 when the vehicle is started by pushing can be reduced.

[0113] Furthermore, according to the above configuration, after the engine 2 is started, the clutch 5 is in a standby state in which the driving force of the engine 2 is not transmitted, and a speed synchronization control is performed to adjust the speed of the engine 2 so as to be synchronized with the speed of the transmission shaft accompanied by the rotation of the electric motor 3. Thus, the decrease in the speed of the transmission shaft when the clutch 5 is engaged can be suppressed, and the mode switching can be performed in a short period of time.

[0114] In addition, according to the above structure, after the clutch 5 is switched to the engaged state, tracking control is performed to gradually switch from the distribution state of the required torque of the first driving mode to the distribution state of the required torque of the second driving mode. In this way, by gradually distributing the distribution of the required torque only from the electric motor 3 to the engine 2, the torque fluctuation of the entire vehicle after the engine is started can be suppressed.

[0115] An embodiment of the present invention has been described above, but the present disclosure is not limited to the above embodiment, and various improvements, changes, and modifications can be made without departing from the spirit of the present invention.

[0116] For example, in the above embodiment, when the clutch 5 is in the semi-clutch state, the control of the throttle opening being an opening above the reference opening and the control of estimating the engine loss torque to correct the motor target torque are executed, but only one of the controls may be executed, or none of the controls may be executed. In addition, in the above embodiment, when the clutch 5 is in the standby state, the speed synchronization control is executed, but the active speed synchronization control may not be executed. In addition, in the above embodiment, when the clutch 5 is in the engaged state, the target torque is tracked, but the tracking control may not be performed. In addition, it may be possible to switch whether to execute these supplementary controls according to the driving state, etc.

Claims

1. A control device for a hybrid vehicle, characterized in that: The invention comprises an electric motor and an engine as driving sources for traveling, a transmission shaft for transmitting the driving force of the electric motor to the driving wheels, and a clutch for switching whether to transmit the driving force of the engine to the transmission shaft; The control device of the hybrid vehicle includes a mode switching control unit that performs mode switching control for switching from a first driving mode in which the engine is stopped and the drive wheels are driven by the power generated by the electric motor to a second driving mode in which the drive wheels are driven by the power generated by the engine and the electric motor according to a predetermined mode switching demand; The mode switching control unit includes a clutch control unit that switches the clutch between a disconnected state in which the driving force of the engine is not transmitted to the transmission shaft and a connected state in which the driving force of the engine is transmitted to the transmission shaft; and a throttle opening control unit that controls the throttle opening of the engine; The clutch control unit controls as follows: When the mode switching request is received, the pressure of the actuator for actuating the clutch is changed from a first pressure corresponding to the disconnected state to a third pressure between the first pressure and a second pressure corresponding to the engaged state and higher than the first pressure, and the engine is started by rotating the transmission shaft by setting the clutch to a semi-clutch state, wherein the semi-clutch state is a state between the disconnected state and the engaged state and the driving force of the engine is transmitted to the transmission shaft; When the engine is determined to be started, the pressure of the actuator is changed from the third pressure to a fourth pressure between the first pressure and the third pressure, so that the clutch is temporarily switched from the semi-clutch state to a standby state, and then the pressure of the actuator is changed from the fourth pressure to the second pressure, so that the clutch is switched to the engaged state, wherein the standby state is a state between the semi-clutch state and the disconnected state and a state in which the driving force of the crankshaft of the engine is not transmitted to the transmission shaft; The third pressure corresponds to the semi-clutch state in which the driving force of the crankshaft of the engine is transmitted to the transmission shaft; The fourth pressure corresponds to the standby state in which the driving force of the crankshaft of the engine is not transmitted to the transmission shaft; The throttle opening control unit makes the throttle opening equal to or greater than a reference opening when the clutch is in the half-clutch state; The reference opening is set to a predetermined opening that is larger than the opening at idle.

2. The control device for a hybrid vehicle according to claim 1, characterized in that: The mode switching control unit includes: a transmission shaft torque estimating unit for estimating the torque of the transmission shaft; a load torque estimating unit that estimates a load torque applied to the hybrid vehicle; and a motor output control unit for performing output control of the electric motor; The motor output control unit estimates the engine loss torque as the driving force of the electric motor consumed when the engine is started based on the torque of the transmission shaft and the load torque when the clutch is in the half-clutch state, and adds the amount of the engine loss torque to the required torque of the electric motor.

3. The control device for a hybrid vehicle according to claim 1, characterized in that: The mode switching control unit includes an engine speed control unit that controls the speed of the engine; The engine speed control unit performs speed synchronization control to make the speed of the transmission shaft associated with the rotation of the engine and the speed of the transmission shaft associated with the rotation of the electric motor consistent with each other when the clutch is in a standby state; The clutch control unit switches the clutch to the engaged state through the rotation speed synchronization control when a difference between a rotation speed of the transmission shaft accompanying rotation of the engine and a rotation speed of the transmission shaft accompanying rotation of the electric motor is within a predetermined reference value.

4. The control device for a hybrid vehicle according to claim 1, characterized in that: A required torque allocating unit is provided for acquiring a total required torque of the entire vehicle and allocating the total required torque to the electric motor and the engine; The required torque distribution unit performs a follow-up control for gradually shifting the required torque distribution state in the first driving mode to the required torque distribution state in the second driving mode after the clutch is shifted to the engaged state.

5. The control device for a hybrid vehicle according to claim 1, characterized in that: The standby state is set to a state without gap with respect to the half-clutch state.

6. The control device for a hybrid vehicle according to claim 1, characterized in that: When receiving the mode switching request while the vehicle is traveling, the clutch control unit sets the clutch to the semi-clutch state to start the engine using the driving of the electric motor or the rotation of the transmission shaft due to the inertia of the vehicle.

7. A control device for a hybrid vehicle, characterized in that: The invention comprises an electric motor and an engine as driving sources for traveling, a transmission shaft for transmitting the driving force of the electric motor to the driving wheels, and a clutch for switching whether to transmit the driving force of the engine to the transmission shaft; The control device of the hybrid vehicle includes a mode switching control unit that performs mode switching control for switching from a first driving mode in which the engine is stopped and the drive wheels are driven by the power generated by the electric motor to a second driving mode in which the drive wheels are driven by the power generated by the engine and the electric motor according to a predetermined mode switching demand; The mode switching control unit includes a clutch control unit that switches the clutch between a disconnected state in which the driving force of the engine is not transmitted to the transmission shaft and a connected state in which the driving force of the engine is transmitted to the transmission shaft; and a throttle opening control unit that controls the throttle opening of the engine; The clutch control unit controls as follows: When the mode switching request is received, the pressure of the actuator for actuating the clutch is changed from a first pressure corresponding to the disconnected state to a third pressure between the first pressure and a second pressure corresponding to the engaged state and higher than the first pressure, and the engine is started by rotating the transmission shaft by setting the clutch to a semi-clutch state, wherein the semi-clutch state is a state between the disconnected state and the engaged state and the driving force of the engine is transmitted to the transmission shaft; When the engine is determined to be started, the pressure of the actuator is changed from the third pressure to a fourth pressure between the first pressure and the third pressure, so that the clutch is temporarily switched from the semi-clutch state to a standby state, and then the pressure of the actuator is changed from the fourth pressure to the second pressure, so that the clutch is switched to the engaged state, wherein the standby state is a state between the semi-clutch state and the disconnected state and a state in which the driving force of the crankshaft of the engine is not transmitted to the transmission shaft; The third pressure corresponds to the semi-clutch state in which the driving force of the crankshaft of the engine is transmitted to the transmission shaft; The fourth pressure corresponds to the standby state in which the driving force of the crankshaft of the engine is not transmitted to the transmission shaft; The hybrid vehicle is a motor two-wheeled vehicle; When receiving the mode switching request, the throttle opening control unit increases the throttle opening compared to before receiving the mode switching request in parallel with the action of the clutch from the disconnected state to the semi-clutch state, and when the clutch is in the semi-clutch state, the throttle opening is increased to an opening greater than a reference opening.

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