阅读说明：本技术 混合动力汽车p挡发动机低温冷起动控制方法 (Low-temperature cold start control method for P-gear engine of hybrid electric vehicle ) 是由 张鹏 宋辉 邢兆林 张天锷 于 2021-09-08 设计创作，主要内容包括：本发明公开了一种混合动力汽车P挡发动机低温冷起动控制方法,包括步骤：S1、低温下P档冷起动标志位成立；S2、整车控制器发出起动发动机指令,并控制动力电池放电；S3、判断发动机是否起动成功；其中,在步骤S3中,若发动机起动失败,且失败次数超过设定值,则高压系统自动下高压电。本发明的混合动力汽车P挡发动机低温冷起动控制方法,可有效避免发动机低温冷起动失败和连续起动后导致动力电池亏电的问题。(The invention discloses a low-temperature cold start control method for a P-gear engine of a hybrid electric vehicle, which comprises the following steps of: s1, a P gear cold start flag bit is established at low temperature; s2, the vehicle control unit sends an engine starting instruction and controls the power battery to discharge; s3, judging whether the engine is started successfully or not; in step S3, if the engine fails to start and the number of failures exceeds a set value, the high-voltage system automatically turns off the high-voltage power. The control method for the low-temperature cold start of the P-gear engine of the hybrid electric vehicle can effectively solve the problems of failure of the low-temperature cold start of the engine and power shortage of a power battery after continuous start.)

1. The control method for the low-temperature cold start of the P-gear engine of the hybrid electric vehicle is characterized by comprising the following steps of:

s1, a P gear cold start flag bit is established at low temperature;

s2, the vehicle control unit sends an engine starting instruction and controls the power battery to discharge;

s3, judging whether the engine is started successfully or not;

in step S3, if the engine fails to start and the number of failures exceeds a set value, the high-voltage system automatically turns off the high-voltage power.

2. The method for controlling a cold start of a hybrid vehicle P-range engine in accordance with claim 1, wherein in step S1, after a strong electric power is applied to the vehicle, it is determined whether an engine cold start flag is established based on an engine water temperature, and when the engine water temperature is lower than a first set value, the engine cold start flag is established and the vehicle enters a cold start mode.

3. The low-temperature cold start control method for the P-range engine of the hybrid electric vehicle according to claim 2, wherein the first set value is-15 ℃.

4. The method for controlling the low-temperature cold start of the P-range engine of the hybrid vehicle according to any one of claims 1 to 3, wherein in the step S2, the discharge power of the power battery is greater than the second set value and the discharge duration reaches the third set value.

5. The method for controlling the cold start of the P-range engine of the hybrid vehicle according to claim 4, wherein the second set value is 6 kw.

6. The method for controlling the low-temperature cold start of the P-range engine of the hybrid vehicle according to claim 4, wherein the third set value is 5 s.

7. The control method for the low-temperature cold start of the P-range engine of the hybrid vehicle according to any one of claims 1 to 6, wherein in the step S3, after the start of the engine, whether the start of the engine is successful is judged according to the actual power of the power battery and the actual state of the engine generated by the engine.

8. The method for controlling the cold start of the P-range engine of the hybrid vehicle according to claim 7, wherein in step S3, if the actual engine operating state is start but the vehicle is not shifted to running and the duration reaches a fourth set value, it is determined that the engine start has failed.

9. The method for controlling the cold start of the P-range engine of the hybrid vehicle according to claim 8, wherein the fourth setting value is 10 s.

10. The method as claimed in claim 7, wherein in step S3, if the actual operating state of the engine has jumped to running, but the actual power of the power battery is positive and continues to discharge, and the power battery does not reach the charging state, it is determined that the engine has failed to start.

Technical Field

The invention belongs to the technical field of hybrid electric vehicles, and particularly relates to a low-temperature cold start control method for a P-gear engine of a hybrid electric vehicle.

Background

The power split hybrid electric vehicle can use a driving motor or an engine as a power source, compared with a traditional vehicle which can only rely on the engine as the power source, in the aspect of driving feeling, the motor has the characteristics of fast torque response, silence and the like relative to the engine, the driving pleasure of a driver can be greatly improved, and meanwhile, the power split hybrid electric vehicle has the advantages of energy conservation, emission pollution reduction, environmental protection and the like, the fuel consumption and the emission policy and regulations are strict day by day, and the environmental protection is in the current, so that the hybrid electric vehicle becomes a new trend of technical development of the automobile industry.

At present, due to the limitation of battery technology, pure electric vehicles are difficult to popularize with great force, and the hybrid electric vehicle which has the advantages of both pure electric vehicles and traditional vehicles becomes the best transitional product at present. The hybrid power driving device used in the hybrid vehicle, namely the electromechanical coupling box provided with the double motors, is additionally provided with the generators and the motors on the basis of taking the traditional vehicle engine as a power source.

The power split hybrid electric vehicle mainly drives an engine, drives a motor to be used under a low-speed working condition or as power compensation, and enables the engine to work in the most economic area by combining the speed regulation effect of a generator on a starter, so that the fuel consumption is reduced. At the same time, the generator is also used as a starter for starting the engine.

On the premise that the engine is not in fault, the engine has the risk of failed starting at low temperature and in the condition that the electric quantity of a power battery is extremely low or in a normal state, if the engine fails to start, the rotating speed of the engine is already increased to more than 1000rpm by the generator, and the engine does not have effective power output at the moment, so that the risk of continuous power shortage of the power battery can be caused.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a low-temperature cold start control method for a P-gear engine of a hybrid electric vehicle, aiming at eliminating the risk of serious power shortage of a power battery after the continuous start failure of the engine in a low-temperature state.

In order to achieve the purpose, the invention adopts the technical scheme that: the control method for the low-temperature cold start of the P-gear engine of the hybrid electric vehicle comprises the following steps:

s1, a P gear cold start flag bit is established at low temperature;

s2, the vehicle control unit sends an engine starting instruction and controls the power battery to discharge;

s3, judging whether the engine is started successfully or not;

in step S3, if the engine fails to start and the number of failures exceeds a set value, the high-voltage system automatically turns off the high-voltage power.

In step S1, after a strong electric power is applied to the entire vehicle, it is determined whether or not the engine cold start flag is established based on the engine water temperature, and when the engine water temperature is lower than the first set value, the engine cold start flag is established and the vehicle enters the cold start mode.

The first set point is-15 ℃.

In step S2, the discharge power of the power battery is greater than the second set value and the discharge duration reaches the third set value.

The second set value is 6 kw.

The third set value is 5 s.

In step S3, after the engine starts to start, it is determined whether the engine has been started successfully based on the actual power of the power battery and the actual state of the engine from the engine.

In step S3, if the engine is actually started but the vehicle is not shifted to the running state and the duration time reaches the fourth setting value, it is determined that the engine start has failed.

The fourth setting value is 10 s.

In step S3, if the actual operating state of the engine has jumped to operation, but the actual power of the power battery is a positive value and continues to discharge, and the power battery does not reach the state of charge, it is determined that the engine has failed to start.

The control method for the low-temperature cold start of the P-gear engine of the hybrid electric vehicle can effectively solve the problems of failure of the low-temperature cold start of the engine and power shortage of a power battery after continuous start.

Drawings

The description includes the following figures, the contents shown are respectively:

FIG. 1 is a flow chart of a low temperature cold start control method for a P-gear engine of a hybrid electric vehicle according to the present invention;

FIG. 2 is a schematic structural diagram of a hybrid transmission;

labeled as: 1. a housing; 2. a drive motor; 3. an ISG motor; 4. a first shaft; 5. a second shaft; 6. a third axis; 7. a fourth axis; 8. a first sun gear; 9. a second sun gear; 10. a first planetary gear; 11. a second planetary gear; 12. a torsional vibration damper; 13. a planet carrier; 14. a fifth shaft; 15. a first reduction gear; 16. a second reduction gear; 17. a third reduction gear; 18. a fourth reduction gear; 19. a fifth reduction gear; 20. a sixth reduction gear; 21. a differential assembly; 22. and a half shaft.

Detailed Description

The following detailed description of the embodiments of the present invention will be given with reference to the accompanying drawings for a purpose of helping those skilled in the art to more fully, accurately and deeply understand the concept and technical solution of the present invention and to facilitate its implementation.

It should be noted that, in the following embodiments, the terms "first", "second" and "third" do not denote absolute differences in structure and/or function, nor do they denote a sequential order of execution, but rather are used for convenience of description.

As shown in FIG. 1, the invention provides a control method for low-temperature cold start of a P-gear engine of a hybrid electric vehicle, which comprises the following steps:

s1, a P gear cold start flag bit is established at low temperature;

s2, the vehicle control unit sends an engine starting instruction and controls the power battery to discharge;

and S3, judging whether the engine is started successfully.

In step S3, if the engine fails to start and the failure frequency exceeds the set value, the high-voltage system automatically turns off high-voltage power, so that the risk of serious power loss of the power battery caused by continuous engine start failure in a low-temperature state can be eliminated.

As shown in fig. 2, the hybrid transmission of the hybrid vehicle includes a housing 1, a driving motor 2, an ISG motor 3, a differential assembly 21, a first shaft 4, a second shaft 5, a third shaft 6, a fourth shaft 7, a stepped planetary gear set and a power transmission mechanism, wherein the driving motor 2, the ISG motor 3, the differential assembly 21, the first shaft 4, the second shaft 5, the third shaft 6, the fourth shaft 7, the stepped planetary gear set and the power transmission mechanism are disposed inside the housing 1. The stepped planetary gear set comprises a first sun gear 8, a second sun gear 9, a first planetary gear 10, a second planetary gear 11 and a planet carrier 13, wherein the first sun gear 8 and the second sun gear 9 are coaxially arranged, the first planetary gear 10 and the second planetary gear 11 are arranged in a plurality, the number of the first planetary gear 10 and the number of the second planetary gear 11 are the same, and each first planetary gear 10 is coaxially and fixedly connected with one second planetary gear 11. The first sun gear 8 meshes with first planetary gears 10, the second sun gear 9 meshes with second planetary gears 11, and the first planetary gears 10 and the second planetary gears 11 are rotatably provided on a carrier 13. The first sun gear 8 is connected with the first shaft 4, the first shaft 4 is connected with the ISG motor 3, the second sun gear 9 is connected with the second shaft 5, the second shaft 5 is connected with the torsional vibration damper 12, the engine is connected with the torsional vibration damper 12, and the first shaft 4 and the second shaft 5 are coaxially arranged. The driving motor 2 and the ISG motor 3 are coaxially arranged, the stepped planetary gear set is positioned between the driving motor 2 and the torsional damper 12, and the driving motor 2 is positioned between the stepped planetary gear set and the ISG motor 3. The power transmission mechanism comprises a third shaft 6 connected with a planet carrier 13, a first reduction gear 15 connected with the third shaft 6, a second reduction gear 16 meshed with the first reduction gear 15, a fourth shaft 7 connected with the driving motor 2, a third reduction gear 17 connected with the fourth shaft 7, a fourth reduction gear 18 meshed with the third reduction gear 17, a fifth reduction gear 19 arranged on the fifth shaft 14 and a sixth reduction gear 20 meshed with the fifth reduction gear 19, wherein the sixth reduction gear 20 is arranged on a differential assembly 21. The fifth shaft 14 is parallel to the first shaft 4, the second reduction gear 16, the fourth reduction gear 18 and the fifth reduction gear 19 are fixedly arranged on the fifth shaft 14, the sixth reduction gear 20 is fixedly connected with the differential assembly 21, the diameter of the fifth reduction gear 19 is smaller than that of the sixth reduction gear 20, and the fifth reduction gear 19 is positioned between the second reduction gear 16 and the fourth reduction gear 18.

As shown in fig. 2, the third shaft 6 and the fourth shaft 7 are hollow shafts, the third shaft 6 is sleeved on the second shaft 5, the second shaft 5 and the third shaft 6 are coaxially arranged, the fourth shaft 7 is sleeved on the first shaft 4, the fourth shaft 7 and the first shaft 4 are coaxially arranged, and the stepped planetary gear set is located between the first reduction gear 15 and the third reduction gear 17.

In step S1, after a strong electric power is applied to the entire vehicle, it is determined whether or not the engine cold start flag is established based on the engine water temperature, and when the engine water temperature is lower than the first set value, the engine cold start flag is established and the vehicle enters the cold start mode.

In the above step S1, the first set value is-15 ℃.

In the present embodiment, in step S1, when the engine water temperature reaches-20 ℃ and the vehicle shift position is P range, the engine cold start flag is set, and the vehicle enters the cold start mode.

In the step S2, the vehicle control unit sends an engine starting instruction to control the generator to drive the engine, and sends the engine starting instruction to the engine cold start flag bit of the power battery, where the discharge capacity of the power battery needs to meet the requirement, the discharge power of the power battery is greater than the second set value, and the discharge duration reaches the third set value, so as to ensure the power required by starting the engine.

In the above step S2, the discharge power of the power battery is greater than the second set value and the discharge duration reaches the third set value.

In step S2, the second set value is 6kw, and the third set value is 5S.

In step S3, after the engine start is started, it is determined whether the engine start is successful based on the actual power of the power battery and the actual state of the engine generated by the engine.

In the above step S3, if the actual engine operating state is start (crank), but the vehicle has not jumped to run (run) and the duration reaches the fourth set value, it is determined that the engine start has failed.

In the above step S3, the fourth setting value is 10S.

In step S3, if the engine operating state has jumped to run (run), but the actual power of the power battery is a positive value and continues to discharge, and the power battery does not reach the state of charge, it is determined that the engine start has failed.

In step S3, after the interval reaches the fifth set value after the engine has failed to start every time, the process returns to step S2, and the engine is not allowed to be started repeatedly during the interval.

In the above step S3, the fifth setting value is 10S.

In step S3, if the engine fails to start and the cumulative number of times of failed starts exceeds 3 times, the high-voltage system automatically turns off the high-voltage power.

The invention is described above with reference to the accompanying drawings. It is to be understood that the specific implementations of the invention are not limited in this respect. Various insubstantial improvements are made by adopting the method conception and the technical scheme of the invention; the present invention is not limited to the above embodiments, and can be modified in various ways.