Hybrid vehicle engine starting control method

Abstract

The invention discloses a hybrid vehicle engine starting control method. The method comprises the following steps that vehicle information is obtained; based on the vehicle information, whether an engine needs to be started or not is judged, and if yes, motor driving request torque information is sent out; controlling the driving motor to output a first torque based on the driving motor request torque information; and after preset time, generator torque information, engine request torque information and driving motor compensation torque information are obtained, and generator output torque, engine output torque and driving motor output compensation torque are controlled. Before the power generator outputs the torque and the engine is started, the driving motor outputs the first torque, so that the whole transmission system is in a meshed state, and when the power generator outputs the torque, the driving motor outputs the compensation torque to counteract part of energy transmitted to the wheel end of the power generator; therefore, only slight vibration can be generated in the starting process of the engine, and shaking and abnormal sound of a transmission system cannot be caused.

Description

Technical Field

[0001] The present invention relates to the technical field of automobiles, and more specifically, to a method for controlling the start of an engine of a hybrid vehicle. Background Art

[0002] As is well known, the engine of a traditional fuel vehicle is started by a starter. The engine of a hybrid vehicle is started by the power battery providing energy and the generator completing the start.

[0003] Currently, in a power-split hybrid vehicle, the engine torque and the wheel-end torque are coupled, and the vibration of the engine can be transmitted to the wheel-end in real time. When the vehicle starts, the power battery provides energy, the generator outputs torque to pull up the engine speed; when the engine speed rises to a certain value, fuel combustion does work and outputs torque to further maintain the operation of the engine, thus completing the start of the engine.

[0004] However, when the vehicle is in a stationary state and the Ready indicator light is on, the generator directly outputs torque to pull up the engine speed, and then fuel injection and combustion occur. In this process, the engine is very likely to generate large vibrations, which are transmitted to the wheel-end, causing jitter and abnormal noise, and affecting the driving experience of users.

[0005] Therefore, how to provide a method for controlling the start of an engine of a hybrid vehicle has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] An object of the present invention is to provide a new technical solution for a method for controlling the start of an engine of a hybrid vehicle.

[0007] According to a first aspect of the present invention, there is provided a method for controlling the start of an engine of a hybrid vehicle, including the following steps:

[0008] Step S1, obtaining vehicle information;

[0009] Step S2, based on the vehicle information, determining whether there is a need to start the engine. If so, sending a requested torque information of the drive motor;

[0010] Step S3, controlling the drive motor to output a first torque based on the requested torque information of the drive motor;

[0011] Step S4, after a preset time, obtaining the generator torque information, the engine requested torque information, and the drive motor compensation torque information, and controlling the generator to output torque, the engine to output torque, and the drive motor to output compensation torque.

[0012] Optionally, the vehicle information includes air conditioner information and vehicle status information. The air conditioner information includes cold air status, warm air status, and off status. The vehicle status information includes idle status, acceleration status, climbing status, and low-speed status. When the air conditioner information is in the warm air status, or the vehicle status information is in the idle status, acceleration status, or climbing status, the vehicle has a demand to start the engine.

[0013] Optionally, step S3 includes the following steps:

[0014] Step S31: Receive the driving motor requested torque information, and obtain the engine friction work, engine target angular acceleration, and actual angular acceleration;

[0015] Step S32: Calculate the driving motor output torque based on the engine friction work, engine target angular acceleration, and actual angular acceleration.

[0016] Optionally, in step S32, the calculation formula for the driving motor output torque is:

[0017] ;

[0018] ;

[0019] ;

[0020] Where: is the target angular acceleration, is the actual angular acceleration, T eng-fric is the engine friction work, T eng_actual is the actual engine output torque, is the driving motor requested torque.

[0021] Optionally, step S4 includes the following steps:

[0022] Step S41: Obtain the delay time t after the driving motor requested torque information is issued;

[0023] Step S42: Determine whether the delay time t is greater than the preset time. If the delay time t is greater than the preset time, obtain the generator torque information, engine requested torque information, and driving motor compensation torque information.

[0024] Optionally, in step S4, obtaining the driving motor compensation torque includes:

[0025] Step S43: Obtain the ring gear torque and calculate the driving motor compensation torque;

[0026] Step S44: Based on the generator torque information, engine requested torque information, and drive motor compensation torque information, control the output torque of the generator, the output torque of the engine, and the output compensation torque of the drive motor.

[0027] Optionally, step S43 includes the following steps:

[0028] Step S431: Obtain the engine friction work and the actual angular acceleration;

[0029] Step S432: Based on the engine friction work and the actual angular acceleration, calculate the ring gear torque; the calculation formula for the ring gear torque is:

[0030] ;

[0031] Where: is the actual angular acceleration, T eng-fric is the engine friction work, is the ring gear torque.

[0032] Optionally, the calculation formula for the drive motor compensation torque is:

[0033] ;

[0034] Where, T wheel_req is the engine requested torque, is the drive motor compensation torque, is the ring gear torque.

[0035] Optionally, after step S4, the following steps are further included:

[0036] Step S5: Obtain the first rotational speed of the engine and the first preset rotational speed;

[0037] Step S6: Based on the first actual rotational speed and the first preset rotational speed of the engine, determine whether the first rotational speed of the engine is greater than the first preset rotational speed. If so, the engine is in the starting state;

[0038] Step S7: Obtain the second rotational speed of the engine and the second preset rotational speed;

[0039] Step S8: Based on the second rotational speed and the second preset rotational speed of the engine, determine whether the second rotational speed of the engine is greater than the second preset rotational speed. If so, the engine runs.

[0040] Optionally, after the said step S8, the following steps are further included:

[0041] Step S9: Obtain the third rotational speed of the engine. When the third rotational speed of the engine is greater than the target rotational speed, control the drive motor to switch to the rotational speed control mode.

[0042] The beneficial effects of the present invention are as follows:

[0043] In the present invention, vehicle information is first obtained, and based on the vehicle information, it is determined whether there is a need to start the engine. If so, torque request information for the drive motor is sent. Then, based on the torque request information for the drive motor, the drive motor is controlled to output a first torque. Next, after a preset time, generator torque information, engine request torque information, and drive motor compensation torque information are obtained, and the generator is controlled to output torque, the engine is controlled to output torque, and the drive motor is controlled to output compensation torque. By enabling the drive motor to output torque before the generator outputs torque and the engine starts, the entire transmission system is in an engaged state, so that only slight vibrations are generated during the engine start process, and no jitter or abnormal noise in the transmission system will occur. Moreover, while the generator outputs torque, the drive motor is controlled to output compensation torque to offset part of the energy of the generator transmitted to the wheel end, further reducing the jitter and abnormal noise caused by the engine start process of the hybrid vehicle to the transmission system, improving the driving experience of users, and avoiding frequent customer maintenance.

[0044] Other features and advantages of the present invention will become clear from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. Description of the Drawings

[0045] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the present invention and, together with the description, serve to explain the principles of the present invention.

[0046] Figure 1 is a flowchart of a method for controlling the start of an engine of a hybrid vehicle according to the present invention;

[0047] Figure 2 is a flowchart for calculating the output torque of the drive motor according to the present invention;

[0048] Figure 3 is for the present invention Figure 1 is a specific flowchart of step S4 in

[0049] Figure 4 is a specific flowchart for calculating the output compensation torque of the drive motor according to the present invention;

[0050] Figure 5 is a flowchart of another embodiment of a method for controlling the start of an engine of a hybrid vehicle according to the present invention;

[0051] Figure 6 is a specific flowchart of a method for controlling the start of an engine of a hybrid vehicle according to the present invention;

[0052] Figure 7 In (a) to (c) in Detailed Embodiments

[0053] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention.

[0054] The following description of at least one exemplary embodiment is merely illustrative in nature and in no way limits the present invention, its application or use.

[0055] Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods and devices should be regarded as part of the specification.

[0056] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0057] As Figures 1 to 6 shown, an embodiment of the present invention provides a method for controlling the start of a hybrid vehicle engine, including the following steps:

[0058] Step S1, obtain vehicle information;

[0059] Step S2, based on the vehicle information, determine whether there is a need to start the engine. If it is determined that there is a need to start the engine, then send the drive motor requested torque information; if it is determined that there is no need to start the engine, then do not send any control information.

[0060] Step S3, based on the drive motor requested torque information, control the drive motor to output a first torque;

[0061] Step S4, after a preset time, obtain the generator torque information, the engine requested torque information and the drive motor compensation torque information, and control the generator to output torque, the engine to output torque, and the drive motor to output compensation torque.

[0062] The present invention first obtains vehicle information, and based on the vehicle information, determines whether there is a need to start the engine. If so, it sends out the requested torque information of the drive motor. Then, based on the requested torque information of the drive motor, it controls the drive motor to output the first torque. Next, after a preset time, it obtains the generator torque information, the engine requested torque information, and the drive motor compensation torque information, and controls the generator to output torque, the engine to output torque, and the drive motor to output compensation torque. By making the drive motor output torque before the generator outputs torque and the engine starts, the entire transmission system is in the meshing state, so that only slight vibrations will occur during the engine start-up process, and no jitter or abnormal noise of the transmission system will be caused. Moreover, when the generator outputs torque, the drive motor outputs compensation torque to offset part of the energy of the generator transmitted to the wheel end, further reducing the jitter and abnormal noise caused by the engine start-up process of the hybrid vehicle to the transmission system, improving the driving experience of users, and avoiding frequent customer maintenance.

[0063] In an embodiment of the engine start control method for a hybrid vehicle of the present invention, the vehicle information includes air conditioner information and vehicle state information. The air conditioner information includes a cold air state, a warm air state, and a closed state, and the vehicle state information includes an idle state, an acceleration state, a climbing state, and a low speed state.

[0064] When the air conditioner information is in the warm air state, or the vehicle state information is in the idle state, the acceleration state, or the climbing state, the vehicle has a need to start the engine.

[0065] When the air conditioner information is in the closed state, or the vehicle state information is in the low speed state, or the air conditioner information is in the cold air state while the vehicle state information is in the low speed state, the vehicle does not have a need to start the engine.

[0066] It should be noted that the above only gives examples of whether the engine has a need to start when the air conditioner information and the vehicle state information are in different states. The vehicle information also includes other types, which are not limited here.

[0067] In an embodiment of the engine start control method for a hybrid vehicle of the present invention, as Figure 2 shown, step S3 includes the following steps:

[0068] Step S31: Receive the requested torque information of the drive motor, and obtain the engine friction work, the engine target angular acceleration, and the actual angular acceleration;

[0069] Step S32: Calculate the output torque of the drive motor based on the engine friction work, the engine target angular acceleration, and the actual angular acceleration.

[0070] Further, in step S31, the calculation formula for the output torque of the drive motor is:

[0071] ;

[0072] ;

[0073] ;

[0074] Wherein: is the target angular acceleration, is the actual angular acceleration, T eng-fric is the engine friction work, T eng_actual is the actual output torque of the engine, is the requested torque of the drive motor.

[0075] Specifically, by first making the drive motor output torque, the meshing state of the entire transmission system can be achieved. It should be noted that the output torque of the drive motor is relatively small and should not be too large, and it can meet the requirement of making the gears or splines in the entire transmission system in the meshing state.

[0076] Since the output shaft of the drive motor, the ring gear, and the wheel are rigidly connected, if the rotation speed or torque of the ring gear or the output shaft of the drive motor is not well controlled, it will be transmitted to the wheel. The present invention can ensure that the rotation speed of the drive motor is relatively stable during the engine starting process, and avoid the problem of the rotation speed of the drive motor jittering and generating abnormal noises in severe cases.

[0077] From Figure 7 in (a) to Figure 7 in (c) as shown, Figure 7 in (a) is the lever principle diagram before starting during the engine starting process when parking, Figure 7 in (b) is the lever principle diagram during starting during the engine starting process when parking, Figure 7 in (c) is the lever principle diagram after starting during the engine starting process when parking. As shown in the figure, when the generator outputs torque, a part of the energy is transmitted to the ring gear. If the drive motor does not output torque in advance to make the transmission system in a tense state, the force transmitted to the ring gear will be transmitted back and forth between the gears in the traditional system, causing abnormal noises (there is a gap between gears in the free state).

[0078] Secondly, the vibration during the engine starting process is weakened after passing through the flywheel, but there is still part of the vibration transmitted into the transmission system, causing the transmission system to shake and make abnormal noises.

[0079] In an implementation manner of the engine starting control method for a hybrid vehicle of the present invention, as Figure 3 shown, the step S4 includes the following steps:

[0080] Step S41, obtain the delay time t after the drive motor requested torque information is sent;

[0081] Step S42: Determine whether the delay time t is greater than the preset time. If the delay time t is greater than the preset time, obtain the generator torque information, the engine requested torque information, and the drive motor compensation torque information.

[0082] If the delay time t is less than the preset time, continue to execute Step S41.

[0083] Specifically, the delay time t is 20 ms.

[0084] In an embodiment of the engine start control method for a hybrid vehicle according to the present invention, as Figure 3 shown, in Step S4, obtaining the drive motor compensation torque includes:

[0085] Step S43: Obtain the ring gear torque and calculate the drive motor compensation torque;

[0086] Step S44: Based on the generator torque information, the engine requested torque information, and the drive motor compensation torque information, control the generator output torque, the engine output torque, and the drive motor output compensation torque.

[0087] Specifically, after 20 ms of the delay time t has passed, the vehicle controller sends the generator torque information, the engine requested torque information, and the drive motor compensation torque information to the vehicle bus, so that the generator outputs torque, the engine outputs torque, and the drive motor outputs compensation torque.

[0088] The output torque of the generator raises the engine speed and is closed-loop with the target angular acceleration at the same time; on the one hand, the output torque of the generator overcomes the engine friction work, and on the other hand, it is output to the ring gear.

[0089] Further, as Figure 4 shown, Step S43 includes the following steps:

[0090] Step S431: Obtain the engine friction work and the actual angular acceleration;

[0091] Step S432: Based on the engine friction work and the actual angular acceleration, calculate the ring gear torque; the calculation formula for the ring gear torque is:

[0092] ;

[0093] Where: is the actual angular acceleration, T eng-fric is the engine friction work, is the ring gear torque.

[0094] Further, the calculation formula for the drive motor compensation torque is:

[0095] ;

[0096] Among them, T wheel_req is the engine requested torque, is the drive motor compensation torque, is the ring gear torque.

[0097] Specifically, after the generator outputs torque, at the same moment, the drive motor continues to increase the torque, that is, the drive motor adds a compensation torque to compensate for the torque at the ring gear end, preventing the torque at the ring gear end from being transmitted to the wheel end during the starting process, causing discomfort such as jitter and abnormal noise.

[0098] In an embodiment of the hybrid vehicle engine starting control method of the present invention, as shown in Figure 5 and Figure 6 , after step S4, the following steps are further included:

[0099] Step S5: Obtain the first rotational speed and the first preset rotational speed of the engine;

[0100] Step S6: Based on the first actual rotational speed and the first preset rotational speed of the engine, determine whether the first rotational speed of the engine is greater than the first preset rotational speed. If so, the engine enters the starting state;

[0101] Step S7: Obtain the second rotational speed and the second preset rotational speed of the engine;

[0102] Step S8: Based on the second rotational speed and the second preset rotational speed of the engine, determine whether the second rotational speed of the engine is greater than the second preset rotational speed. If so, the engine runs.

[0103] Specifically, the second rotational speed is greater than the first rotational speed, and the second preset rotational speed is greater than the first preset rotational speed.

[0104] When the first rotational speed of the engine is greater than the first preset rotational speed, the engine enters the starting state; when the second rotational speed of the engine is greater than the second preset rotational speed, the engine runs, that is, the engine completes starting. At this time, the engine controller controls the fuel injector to inject fuel.

[0105] Among them, the fuel injection timing is calibrated according to the requirements of the entire system. Fuel injection can be performed before starting the vehicle, during the starting process, or after the engine enters ignition; for example, when the engine load is large and starting is difficult at low temperatures, fuel injection can be advanced to output torque, which helps the engine start.

[0106] In an embodiment of the hybrid vehicle engine starting control method of the present invention, as shown in Figure 5 and Figure 6 , after the said step S8, the following steps are further included:

[0107] Step S9: Obtain the third rotational speed of the engine. When the third rotational speed of the engine is greater than the target rotational speed, control the drive motor to switch to the rotational speed control mode.

[0108] Specifically, the third rotational speed is greater than the first rotational speed and the second rotational speed, and the target rotational speed is greater than the first preset rotational speed and the second preset rotational speed. It should be noted that the target rotational speed is merely a value set in the vehicle controller. When the engine rotational speed reaches this value, the drive motor is switched to the rotational speed control mode.

[0109] In the rotational speed control mode, the torque generated by the motor is set to a certain fixed value, and its rotational speed is adjusted according to the change of the applied voltage or current. In the speed control mode, the operator can change the rotational speed of the motor by adjusting the voltage or current, while the torque output remains stable.

[0110] When the third rotational speed of the engine is greater than the target rotational speed, control the drive motor to switch to the rotational speed control mode; at this time, the engine controller controls the engine fuel injection volume according to the requested torque of the vehicle controller to meet the request of the vehicle controller. At the same time, the generator control unit controls and adjusts the engine rotational speed to make the engine operating point in the economic zone.

[0111] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A method for controlling the engine start of a hybrid vehicle, characterized in that, It includes the following steps: Step S1, obtain vehicle information; Step S2, based on the vehicle information, determine whether there is a need to start the engine. If so, send the requested torque information of the drive motor; Step S3, based on the requested torque information of the drive motor, control the drive motor to output the first torque; Step S4, after a preset time, obtain the generator torque information, the requested torque information of the engine, and the compensation torque information of the drive motor, and control the generator to output torque, the engine to output torque, and the drive motor to output compensation torque.

2. The engine starting control method for a hybrid vehicle according to claim 1, characterized in that, The vehicle information includes air-conditioning information and vehicle status information. The air-conditioning information includes cold air status, warm air status, and off status. The vehicle status information includes idle status, acceleration status, climbing status, and low-speed status. When the air-conditioning information is in the warm air status, or the vehicle status information is in the idle status, acceleration status, or climbing status, the vehicle has a need to start the engine.

3. The method for controlling the start of a hybrid vehicle engine according to claim 1, characterized in that, Step S3 includes the following steps: Step S31, receive the requested torque information of the drive motor, and obtain the engine friction work, the engine target angular acceleration, and the actual angular acceleration; Step S32, based on the engine friction work, the engine target angular acceleration, and the actual angular acceleration, calculate the output torque of the drive motor.

4. The method for controlling the start of a hybrid vehicle engine according to claim 3, wherein, In step S32, the calculation formula for the output torque of the drive motor is: ； ； ； Wherein: is the target angular acceleration, is the actual angular acceleration, T eng-fric is the engine friction work, T eng_actual is the actual output torque of the engine, is the drive motor requested torque.

5. The method for controlling the start of a hybrid vehicle engine according to claim 1, characterized in that Step S4 includes the following steps: Step S41, obtain the delay time t after sending the requested torque information of the drive motor; Step S42, determine whether the delay time t is greater than the preset time. If the delay time t is greater than the preset time, obtain the generator torque information, the requested torque information of the engine, and the compensation torque information of the drive motor.

6. The method for controlling the start of a hybrid vehicle engine according to claim 1, wherein In step S4, obtaining the compensation torque of the drive motor includes: Step S43, obtain the ring gear torque, and calculate the compensation torque of the drive motor; Step S44, based on the generator torque information, the requested torque information of the engine, and the compensation torque information of the drive motor, control the generator to output torque, the engine to output torque, and the drive motor to output compensation torque.

7. The engine starting control method for a hybrid vehicle according to claim 6, wherein Step S43 includes the following steps: Step S431, obtain the engine friction work and the actual angular acceleration; Step S432, based on the engine friction work and the actual angular acceleration, calculate the ring gear torque; the calculation formula for the ring gear torque is: ； Wherein: is the actual angular acceleration, T eng-fric is the engine friction work, is the ring gear torque; Step S433, obtain the wheel end torque; Step S434, based on the ring gear torque and the wheel end torque, calculate the compensation torque of the drive motor.

8. The engine starting control method for a hybrid vehicle according to claim 7, characterized in that, The calculation formula for the compensation torque of the drive motor is: ； Among them, T wheel_req is the wheel-end torque, is the drive motor compensation torque, is the ring gear torque.

9. The engine starting control method for a hybrid vehicle according to claim 1, wherein After step S4, it further includes the following steps: Step S5, obtain the first speed of the engine and the first preset speed; Step S6, based on the first actual speed of the engine and the first preset speed, determine whether the first speed of the engine is greater than the first preset speed. If so, the engine is in the starting state; Step S7, obtain the second speed of the engine and the second preset speed; Step S8, based on the second speed of the engine and the second preset speed, determine whether the second speed of the engine is greater than the second preset speed. If so, the engine runs.

10. The engine starting control method for a hybrid vehicle according to claim 9, characterized in that, After step S8, it further includes the following steps: Step S9: Obtain the third rotational speed of the engine. When the third rotational speed of the engine is greater than the target rotational speed, control the drive motor to switch to the rotational speed control mode.

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