Engine starting control method and vehicle under battery failure during hybrid vehicle driving

Abstract

The present invention discloses an engine starting control method and a vehicle under battery failure during the running of a hybrid vehicle, including: S10, obtaining and judging high-voltage system faults; S20, judging the engine state and engine starting conditions; S30, when the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time, the engine has not started and meets the conditions for starting the engine, the power system controller requests to start the engine; S40, the transmission controller controls the K0 clutch to be in a semi-engaged state, reduces the pressing force of the K1 and K2 clutches, and after the motor controller drags the engine to a preset speed, the power system controller requests fuel injection and ignition from the engine controller; S50, after the engine controller feedbacks that the engine has started successfully, the power system controller requests to gradually and fully close the K0 clutch, the K1 and K2 clutches, and exits the starting process. The present invention can improve the driving safety of the vehicle.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle engine control, and particularly relates to a method for controlling engine starting under battery failure during the running of a hybrid vehicle and a vehicle. Background Art

[0002] The usage environment of vehicles is relatively complex. Situations such as ice and snow, high temperature, high cold, bumpiness, wading, and long-term storage will all have a certain impact on the power system of the vehicle. Moreover, as the mileage of the vehicle increases, the probability of the power system failing will further increase. Compared with traditional fuel vehicles, hybrid vehicles have two power sources. For certain scenarios, when one power source fails, by reasonably controlling the other power source, the power performance and safety problems caused by the failure of a certain power source can be avoided or reduced.

[0003] For example, the starter-alternator control during high-voltage battery failure states disclosed in the patent document CN101841185A discloses a control method for a mild hybrid electric vehicle (HEV) with a belt-driven alternator starter system to execute a pair of default limp-home modes from the perspective of the power system according to the engine state during a high-voltage power failure and to energize the corresponding auxiliary systems. Another example is the failure limp-home control method and device for a hybrid vehicle disclosed in the patent document CN106184198A, which discloses a failure limp-home control method corresponding to the severity level of the failure of a hybrid vehicle. This method is based on a power system with an auxiliary starter and expounds the working process of its failure limp-home control from a macroscopic perspective according to the failure states of components, and judges whether it is necessary to start the engine, but does not involve the specific control process of starting the engine. Moreover, the methods described in CN101841185A and CN106184198A are not applicable to plug-in hybrid vehicles with a single-motor parallel configuration.

[0004] Therefore, it is necessary to develop a new method for controlling engine starting under battery failure during the running of a hybrid vehicle and a vehicle. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for controlling engine starting under battery failure during the running of a hybrid vehicle and a vehicle, which can start the engine when the system detects that the failure is limited discharge capacity of the power battery and the battery controller will actively cut off the high-voltage relay after a preset time, and the engine has not started but meets the conditions for starting the engine, so as to ensure the safe operation of the vehicle.

[0006] First aspect, a method for controlling engine starting under battery failure during the driving of a hybrid vehicle, which is used for a hybrid power system equipped with a P2 configuration of a dual-clutch transmission. The system includes a power system controller, an engine controller, a motor controller, a battery controller, and a transmission controller respectively connected to the power system controller, an engine connected to the engine controller, a power battery connected to the battery controller, a P2 motor respectively connected to the motor controller and the motor controller, a transmission assembly connected to the transmission controller. A K0 clutch is connected between the engine and the P2 motor. The transmission assembly has a K1 clutch, a K2 clutch, and a clutch controller. The clutch controller is respectively connected to the K1 clutch, the K2 clutch, and the power system controller. The P2 motor is respectively connected to the K1 clutch and the K2 clutch. The control method includes the following steps:

[0007] Step S10, obtaining and judging high-voltage system faults: The power system controller receives the faults fed back by the battery controller and confirms whether the faults are that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time;

[0008] Step S20, judging the engine state and engine starting conditions: The power system controller judges the current working state of the engine. If the engine is not started, it judges whether there are conditions for starting the engine;

[0009] Step S30, requesting engine start: If it is judged that the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time, and the engine is not started but meets the conditions for starting the engine, the power system controller requests to start the engine;

[0010] Step S40, performing engine starting actions: The transmission controller controls the K0 clutch to be in a semi-engaged state, and at the same time reduces the pressing force of the K1 and K2 clutches. At the same time, after the motor controller drags the engine to a preset speed, the power system controller requests fuel injection and ignition from the engine controller;

[0011] Step S50, after the engine controller feedbacks that the engine starting is successful, the power system controller requests to gradually and fully close the K0 clutch, the K1 and K2 clutches, and exits this starting process.

[0012] Optionally, judging whether there are conditions for starting the engine specifically includes:

[0013] The torque that the vehicle can transfer to the engine flywheel end is obtained through vehicle mass, acceleration, wheel radius, transmission gear, mechanical efficiency, and the first compensation torque. If the calculated torque plus the remaining capacity of the current motor is greater than the friction torque of the current engine, it indicates that the engine starting condition is met; otherwise, it is not. Among them, the first compensation torque is obtained through vehicle calibration.

[0014] Optionally, step S40 is specifically as follows:

[0015] S401, the powertrain controller requests the K0 clutch to enter the semi-closed mode, and the transmission controller performs the action of gradually closing the K0 clutch through the fitting rate control but not completely closing the K0 clutch.

[0016] S402, during the process of fitting the K0 clutch, the powertrain controller continuously requests the K1K2 clutch closing mode from the transmission controller, and at the same time sends a target transmission torque request to the K1K2 clutch. The target transmission torque is equal to the actual transmission torque of the K1K2 clutch at the previous moment minus the second compensation torque. Among them, the second compensation torque is obtained through vehicle calibration. After receiving the target transmission torque, the clutch controller reduces the pressing force of the K1K2 clutch to make it in a fitting but not completely locked state to ensure that there is a speed difference between the input shaft and the output shaft of the K1K2 clutch.

[0017] Step S403, when the powertrain controller monitors that the speed difference between the input shaft and the output shaft of the K1K2 clutch reaches the target value, it increases the fitting degree of the K0 clutch and quickly drags the engine to a higher speed, but still does not completely close the K0 clutch.

[0018] Step S404, when the powertrain controller monitors that the speed of the engine flywheel end is dragged to slightly lower than the normal starting speed threshold, it sends an injection and ignition request to the engine controller. The speed threshold is obtained by looking up a table according to the water temperature of the engine. After receiving the injection and ignition request, the engine controller controls the engine to inject fuel and ignite.

[0019] Optionally, in step S402,

[0020] If the output shaft speed of the K1K2 clutch is less than the engine idle speed, the target speed of the input shaft of the K1K2 clutch = engine idle speed + the first compensation speed, and the first compensation speed is obtained through vehicle calibration.

[0021] If the output shaft speed of the K1K2 clutch is greater than or equal to the engine idle speed, the target speed of the input shaft of the K1K2 clutch = the output shaft speed of the K1K2 clutch at the previous moment + the second compensation speed, and the second compensation speed is obtained through vehicle calibration.

[0022] Optionally, step S50 specifically includes:

[0023] Step S501: After the powertrain controller receives the signal that the engine has started successfully, it requests the engine to operate in a speed control mode, and uses the larger value between the engine target idle speed and the input shaft speed of the K1K2 clutch plus a third compensation speed as the engine target speed for control. After the engine speed reaches the target speed, the K0 clutch is fully closed, and during this period, the engine target speed remains unchanged; wherein, the third compensation speed is obtained through vehicle calibration.

[0024] Step S502: After the K0 clutch is locked, if the output shaft speed of the K1K2 clutch is greater than or equal to the engine idle speed, it requests to fully close the K1K2 clutch. After the powertrain controller receives the feedback that the K1K2 is fully locked, it exits the starting process; if the output shaft speed of the K1K2 clutch is less than the engine idle speed, it maintains the current closed state of the K1K2 clutch, and then exits this starting process.

[0025] In a second aspect, a vehicle according to the present invention is equipped with a hybrid power system in a P2 configuration of a dual-clutch transmission and adopts the engine starting control method for a hybrid vehicle under battery failure during driving as described in the present invention.

[0026] The present invention has the following advantages: The control method described in the present invention is developed based on a hybrid power system in a P2 configuration of a dual-clutch transmission. During the driving of the vehicle, when the system detects that the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time, and the engine has not started but meets the conditions for starting the engine, it attempts to start the engine according to a specific control process to ensure the safe operation of the vehicle. Otherwise, it does not attempt to start the engine. Description of the Drawings

[0027] Figure 1 Structural schematic diagram of the P2 configuration single-motor dual-clutch hybrid power system in this embodiment;

[0028] Figure 2 Overall control flow schematic diagram of the method in this embodiment;

[0029] Figure 3 Engine starting action flow diagram in this embodiment. Detailed Embodiment

[0030] The present invention will be described in detail below with reference to the drawings.

[0031] Such as Figure 1 and Figure 3As shown in the figure, in this embodiment, a method for controlling engine starting under battery failure during the driving of a hybrid vehicle is used for a hybrid power system equipped with a P2 configuration of a dual-clutch transmission. The system includes a power system controller, an engine controller, a motor controller, a battery controller, and a transmission controller respectively connected to the power system controller, an engine connected to the engine controller, a power battery connected to the battery controller, a P2 motor respectively connected to the motor controller and the motor controller, and a transmission assembly connected to the transmission controller. A K0 clutch is connected between the engine and the P2 motor. The transmission assembly has a K1 clutch, a K2 clutch, and a clutch controller. The clutch controller is respectively connected to the K1 clutch, the K2 clutch, and the power system controller. The P2 motor is respectively connected to the K1 clutch and the K2 clutch. The control method includes the following steps:

[0032] Step S10, obtaining and judging high-voltage system faults: The power system controller receives the faults fed back by the battery controller and confirms whether the faults are that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time.

[0033] In this embodiment, when the battery controller feeds back to the power system controller that the power battery discharge capacity is limited, there is still a certain power output within the first time threshold. If the engine has not run after exceeding the first time threshold and cannot meet the power supply requirements of the whole vehicle, the battery controller will actively cut off the high-voltage relay, and then the whole vehicle powers off under high voltage. If the engine has already run within the first time threshold, the high-voltage relay will not be disconnected, and the whole vehicle runs through a preset safety mode.

[0034] Step S20, judging the engine state and engine starting conditions: The power system controller judges the current working state of the engine. If the engine has not started, it judges whether there are conditions for starting the engine.

[0035] In this embodiment, if the engine is in the running state or the starting state, the existing actions are maintained. If the engine has not started, the torque that the vehicle can transfer to the engine flywheel end is obtained through the vehicle mass, acceleration, wheel radius, transmission gear, mechanical efficiency, and the first compensation torque (considering calculation errors). If the calculated torque plus the remaining capacity of the current motor is greater than the current engine friction torque, it means that there are conditions for starting the engine; otherwise, there are no conditions. The first compensation torque is obtained through on-vehicle calibration.

[0036] Step S30, requesting engine starting: If it is judged that the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time, and the engine has not started but meets the conditions for starting the engine, the power system controller requests to start the engine.

[0037] Step S40, perform the engine starting operation: The transmission controller controls the K0 clutch to be in a semi-engaged state, and at the same time reduces the clamping force of the K1 and K2 clutches. Meanwhile, after the motor controller drags the engine to a preset speed, the power system controller requests fuel injection and ignition from the engine controller.

[0038] In this embodiment, the step S40 specifically includes:

[0039] S401, the power system controller requests the K0 clutch to enter the semi-closed mode, and the transmission controller performs the action of gradually closing the K0 clutch through the fitting rate control, but does not completely close the K0 clutch.

[0040] S402, during the process of fitting the K0 clutch, the power system controller continuously requests the K1 and K2 clutch closing mode from the transmission controller, and at the same time sends a target transmission torque request to the K1 and K2 clutches. The target transmission torque is equal to the actual transmission torque of the K1 and K2 clutches at the previous moment minus the second compensation torque. The second compensation torque is obtained through vehicle calibration. After receiving the target transmission torque, the clutch controller reduces the clamping force of the K1 and K2 clutches to make it in a fitting but not completely locked state, so as to ensure that there is a speed difference between the input shaft and the output shaft of the K1 and K2 clutches.

[0041] If the output shaft speed of the K1 and K2 clutches is less than the engine idle speed, the target speed of the input shaft of the K1 and K2 clutches = the engine idle speed + the first compensation speed, and the first compensation speed is obtained through vehicle calibration; in an example, the first compensation speed is 150 rpm.

[0042] If the output shaft speed of the K1 and K2 clutches is greater than or equal to the engine idle speed, the target speed of the input shaft of the K1 and K2 clutches = the output shaft speed of the K1 and K2 clutches at the previous moment + the second compensation speed, and the second compensation speed is obtained through vehicle calibration. In an example, the second compensation speed is 200 rpm.

[0043] Step S403, when the power system controller monitors that the speed difference between the input shaft and the output shaft of the K1 and K2 clutches reaches the target value, increase the fitting degree of the K0 clutch, quickly drag the engine to a higher speed, but still do not completely close the K0 clutch.

[0044] Step S404, when the power system controller monitors that the speed at the engine flywheel end is dragged to be slightly lower than the normal starting speed threshold, send a fuel injection and ignition request to the engine controller. The speed threshold is obtained by looking up a table according to the engine water temperature. After receiving the fuel injection and ignition request, the engine controller controls the engine to inject fuel and ignite.

[0045] Step S50: After the engine controller feeds back that the engine has started successfully, the powertrain controller requests to gradually and fully close the K0 clutch, K1, and K2 clutches, and exits this starting process.

[0046] In this embodiment, the specific steps of step S50 include:

[0047] Step S501: After the powertrain controller receives the signal that the engine has started successfully, it requests the engine to operate in a speed control mode, and uses the larger value between the engine target idle speed and the input shaft speed of the K1 and K2 clutches plus a third compensation speed as the engine target speed for control. After the engine speed reaches the target speed, the K0 clutch is fully closed, and during this period, the engine target speed remains unchanged. The third compensation speed is obtained through vehicle calibration. Generally speaking, the third compensation speed is greater than 0.

[0048] Step S502: After the K0 clutch is locked, if the output shaft speed of the K1 and K2 clutches is greater than or equal to the engine idle speed, it requests to fully close the K1 and K2 clutches. After the powertrain controller receives the feedback that the K1 and K2 are fully locked, it exits the starting process; if the output shaft speed of the K1 and K2 clutches is less than the engine idle speed, it maintains the current closed state of the K1 and K2 clutches, and then exits this starting process.

[0049] In this embodiment, the transmission assembly has a K1 clutch, a K2 clutch, and a clutch controller. One clutch is used to control odd gears such as 1, 3, 5, etc. and reverse gear, and the other clutch is used to control even gears such as 2, 4, 6, etc. When one clutch is working, the other clutch is ready. The K1 and K2 clutches in this embodiment mean that when the currently working clutch is the K1 clutch, the K1 and K2 clutches refer to the K1 clutch; when the currently working clutch is the K2 clutch, the K1 and K2 clutches refer to the K2 clutch.

[0050] In this embodiment, a vehicle is equipped with a hybrid power system with a dual-clutch transmission P2 configuration and adopts the engine starting control method under battery failure during the driving of the hybrid vehicle as described in this embodiment.

[0051] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A method for controlling engine starting under battery failure during the running of a hybrid vehicle, characterized in that, For a hybrid system equipped with a dual-clutch transmission in P2 configuration, the system includes a powertrain controller, an engine controller, a motor controller, a battery controller, and a transmission controller respectively connected to the powertrain controller, an engine connected to the engine controller, a power battery connected to the battery controller, a P2 motor respectively connected to the motor controller and the motor controller, a transmission assembly connected to the transmission controller. A K0 clutch is connected between the engine and the P2 motor. The transmission assembly has a K1 clutch, a K2 clutch, and a clutch controller. The clutch controller is respectively connected to the K1 clutch, the K2 clutch, and the powertrain controller. The P2 motor is respectively connected to the K1 clutch and the K2 clutch. Its control method includes the following steps: Step S10, high-voltage system fault acquisition and judgment: The powertrain controller receives a fault feedback from the battery controller and confirms whether the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time; Step S20, engine state and engine starting condition judgment: The powertrain controller judges the current working state of the engine. If the engine is not started, it judges whether there are conditions for starting the engine; Step S30, request to start the engine: If it is judged that the fault is that the power battery discharge capacity is limited and the battery controller will actively cut off the high-voltage relay after a preset time, and the engine is not started but meets the conditions for starting the engine, then the powertrain controller requests to start the engine; Step S40, execute the engine starting action: The transmission controller controls the K0 clutch to be in a semi-engaged state, and at the same time reduces the pressing force of the K1K2 clutch. At the same time, after the motor controller drags the engine to a preset speed, the powertrain controller requests fuel injection and ignition from the engine controller; After the engine controller feedbacks that the engine starting is successful, the powertrain controller requests to gradually and fully close the K0 clutch and the K1 K2 clutch, and exits the starting process.

2. The engine starting control method during battery failure in a hybrid vehicle running according to claim 1, characterized in that: Judge whether there are conditions for starting the engine. Specifically: The torque that the vehicle can transfer to the engine flywheel end is obtained through the vehicle mass, acceleration, wheel radius, transmission gear, mechanical efficiency, and the first compensation torque. If the calculated torque plus the remaining capacity of the current motor is greater than the current engine friction torque, it means that there are conditions for starting the engine; otherwise, there are no conditions. The first compensation torque is obtained through vehicle calibration.

3. The engine starting control method under battery failure during hybrid vehicle driving according to claim 1 or 2, characterized in that: The specific content of the said step S40 is: S401, the powertrain controller requests the K0 clutch to enter the semi-closed mode, and the transmission controller executes the action of gradually closing the K0 clutch through the fitting rate control but not fully closing the K0 clutch; S402. During the process of engaging the K0 clutch, the powertrain controller continuously requests the transmission controller for the K1K2 clutch closing mode, and at the same time sends a target transmission torque request to the K1K2 clutch. The target transmission torque is equal to the actual transmission torque of the K1K2 clutch at the previous moment minus the second compensation torque, where the second compensation torque is obtained through vehicle calibration. After receiving the target transmission torque, the clutch controller reduces the clamping force of the K1K2 clutch to make it in an engaged but not fully locked state, so as to ensure that there is a rotational speed difference between the input shaft and the output shaft of the K1K2 clutch. Step S403. When the powertrain controller monitors that the rotational speed difference between the input shaft and the output shaft of the K1K2 clutch reaches the target value, it increases the engagement degree of the K0 clutch, quickly drags the engine to a higher rotational speed, but still does not fully close the K0 clutch. Step S404. When the powertrain controller monitors that the rotational speed at the engine flywheel end is dragged to be slightly lower than the rotational speed threshold for normal starting, it sends an injection and ignition request to the engine controller. The rotational speed threshold is obtained by looking up a table according to the engine water temperature. After receiving the injection and ignition request, the engine controller controls the engine to inject fuel and ignite.

4. The engine starting control method under battery failure during the running of a hybrid vehicle according to claim 3, characterized in that: In the said step S402, If the rotational speed of the output shaft of the K1K2 clutch is less than the engine idle speed, then the target rotational speed of the input shaft of the K1K2 clutch = engine idle speed + the first compensation rotational speed, where the first compensation rotational speed is obtained through vehicle calibration. If the rotational speed of the output shaft of the K1K2 clutch is greater than or equal to the engine idle speed, then the target rotational speed of the input shaft of the K1K2 clutch = the rotational speed of the output shaft of the K1K2 clutch at the previous moment + the second compensation rotational speed, where the second compensation rotational speed is obtained through vehicle calibration.

5. The engine starting control method under battery failure during the running of a hybrid vehicle according to claim 4, characterized in that: The said step S50 specifically includes: Step S501. After receiving the signal that the engine has started successfully, the powertrain controller requests the engine to operate in a rotational speed control mode, and uses the larger value between the engine target idle speed and the rotational speed of the input shaft of the K1K2 clutch plus the third compensation rotational speed as the engine target rotational speed for control. After the engine rotational speed reaches the target rotational speed, the K0 clutch is fully closed, and during this period, the engine target rotational speed remains unchanged; where the third compensation rotational speed is obtained through vehicle calibration. Step S502. After the K0 clutch is locked, if the rotational speed of the output shaft of the K1K2 clutch is greater than or equal to the engine idle speed, then request to fully close the K1K2 clutch. After the powertrain controller receives the feedback that the K1K2 is fully locked, it exits the starting process; if the rotational speed of the output shaft of the K1K2 clutch is less than the engine idle speed, then maintain the current closed state of the K1K2 clutch, and then exit this starting process.

6. A vehicle equipped with a hybrid system in a dual-clutch transmission P2 configuration, characterized in that: Adopt the engine starting control method under battery failure during the driving of a hybrid vehicle as described in any one of claims 1 to 5.

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