Control method for preventing reverse rotation of engine and related device

Abstract

The invention discloses a control method and a related device for preventing reverse rotation of an engine, which are applied to a vehicle using an oil-electric hybrid power system, firstly, a gear state is obtained, and when it is determined that the vehicle is in an upshift process, the transmission ratio of the power system at the current moment and the rotation speed drop rate of a motor at the previous moment are obtained; according to the transmission ratio of the current moment and the rotation speed reduction rate of the motor at the previous moment, based on a pre-constructed rotation speed relation model, the rotation speed reduction rate which does not cause reverse rotation of the engine at the current moment is determined, and finally the rotation speed reduction rate of the motor at the current moment is controlled to be the maximum rotation speed reduction rate. Therefore, aiming at the working condition that the rotation speed of the motor is rapidly reduced in the upshift process to possibly cause reverse rotation of the engine, the rotation speed reduction rate of the motor can be controlled in time, so that the reduction speed of the rotation speed in the upshift process is smoother, and the situation that the rotation speed of the motor is excessively reduced to cause reverse rotation of the engine is avoided; therefore, a better anti-reverse effect is achieved.

Description

Technical Field

[0001] The present application relates to the field of vehicle technology, and in particular to a control method and related device for preventing engine reversal. Background Art

[0002] In a hybrid vehicle, the motor and the engine provide power together to drive the vehicle. During vehicle operation, there is a situation where the engine reverses, which will damage the performance of the engine.

[0003] In the related art, the vehicle's control system can calculate the target output torque of the motor based on the speed difference between the actual engine speed and the ideal engine speed through a proportional-integral-derivative (PID) controller, and adjust the actual output torque of the motor to act on the engine to prevent the engine from reversing.

[0004] However, due to the rapid changes in vehicle operating conditions and the slow response speed of the PID controller, the anti-reverse effect is not good in applications to prevent engine reversal. Summary of the invention

[0005] In view of this, the present application provides a control method for preventing engine reversal. By acquiring the gear information of the vehicle and controlling the rate of decrease of the motor speed when the vehicle is in the process of upshifting, the rate of rapid decrease of the motor speed caused by the overly fast upshifting process can be effectively reduced, thereby preventing the engine from being reversed due to the motor speed decreasing too quickly.

[0006] To solve the above problems, the technical solutions provided by this application are as follows:

[0007] In one aspect, the present application provides a control method for preventing engine reverse rotation, comprising:

[0008] Get the gear status of the vehicle;

[0009] If the gear state is in the process of upshifting, the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment are obtained, wherein the speed reduction rate is the speed reduction rate of the motor speed per unit time, and the transmission ratio is the speed ratio between the input shaft and the output shaft of the power system, and the power system is powered by the engine and the motor;

[0010] According to the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, a target speed reduction rate is determined based on a pre-constructed speed relationship model, wherein the speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, and the target speed reduction rate is used to identify the speed reduction rate that will not cause engine reversal at the current moment;

[0011] The speed reduction rate of the motor at the current moment is controlled to be at most the target speed reduction rate.

[0012] In a possible implementation, the method further includes:

[0013] Obtaining the state of the engine;

[0014] If the state of the engine is during shutdown, obtaining the torque after motor compensation;

[0015] If the torque of the motor after compensation is a negative torque, the transmission torque transmitted from the engine to the motor is obtained, wherein the negative torque is a torque opposite to the working direction of the power system;

[0016] If the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero, the magnitude of the compensated torque of the motor is reduced by at least the difference.

[0017] In a possible implementation, the method further includes:

[0018] Obtaining the state of the engine;

[0019] If the state of the engine is stopped and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the last moment are obtained, and the torque reduction rate at the last moment is the difference between the torque of the motor at the previous two moments and the torque of the motor at the last moment;

[0020] Determining the torque difference according to the difference between the required recovery torque and the actual recovery torque;

[0021] According to the torque reduction rate at the previous moment and the torque difference, a target torque reduction rate is determined based on a pre-constructed torque relationship model, wherein the torque relationship model is used to identify the relationship between different torque reduction rates at the previous moment and different torque differences and different target torque reduction rates, and the target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment;

[0022] The torque reduction rate of the motor at the current moment is controlled to be at most the target torque reduction rate.

[0023] In a possible implementation, the transmission ratio at the current moment is obtained in the following manner:

[0024] Acquire the transmission ratio of the target gear, the transmission ratio of the initial gear, and the gear shifting progress at the current moment, wherein the initial gear is used to identify the gear of the vehicle at the beginning of the upshift process, the target gear is used to identify the gear to be reached by the vehicle at the end of the upshift process, and the gear shifting progress is used to identify the completion progress of the upshift process;

[0025] The transmission ratio at the current moment is determined according to the transmission ratio of the target gear, the transmission ratio of the actual gear, and the gear shifting progress at the current moment.

[0026] In a possible implementation, the power system is a power-split multi-speed hybrid power system.

[0027] In another aspect, the present application provides a control device for preventing engine reversal, comprising an acquisition unit, a determination unit and a control unit:

[0028] The acquisition unit is used to acquire the gear status of the vehicle;

[0029] The acquisition unit is further used to acquire the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment if the gear state is in the process of upshifting, wherein the speed reduction rate is the speed reduction rate of the motor speed per unit time, and the transmission ratio is the speed ratio between the input shaft and the output shaft of the power system, wherein the power system is powered by the engine and the motor;

[0030] The determination unit is used to determine the target speed reduction rate according to the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, based on a pre-constructed speed relationship model, wherein the speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, and the target speed reduction rate is used to identify the speed reduction rate that will not cause the engine to reverse at the current moment;

[0031] The control unit is used to control the current speed reduction rate of the motor to be at most the target speed reduction rate.

[0032] In a possible implementation, the acquiring unit is further configured to:

[0033] Obtaining the state of the engine;

[0034] If the state of the engine is during shutdown, obtaining the torque after motor compensation;

[0035] If the torque of the motor after compensation is a negative torque, the transmission torque transmitted from the engine to the motor is obtained, wherein the negative torque is a torque opposite to the working direction of the power system;

[0036] The control unit is further configured to reduce the magnitude of the motor's compensated torque by at least the difference if the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero.

[0037] In a possible implementation, the acquiring unit is further configured to:

[0038] Obtaining the state of the engine;

[0039] If the state of the engine is stopped and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the previous moment are obtained, where the torque reduction rate is the difference between the torque of the motor at the previous two moments and the torque of the motor at the previous moment;

[0040] The determining unit is further configured to determine the torque difference according to the difference between the required recovery torque and the actual recovery torque;

[0041] The determining unit is further used to determine a target torque reduction rate according to the torque reduction rate at the previous moment and the torque difference value based on a pre-constructed torque relationship model, wherein the torque relationship model is used to identify the relationship between different torque reduction rates at the previous moment and different torque differences and different target torque reduction rates, and the target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment;

[0042] The control unit is further configured to control the torque reduction rate of the motor at a current moment to be at most the target torque reduction rate.

[0043] In a possible implementation, the transmission ratio at the current moment is obtained in the following manner:

[0044] Acquire the transmission ratio of the target gear, the transmission ratio of the initial gear, and the gear shifting progress at the current moment, wherein the initial gear is used to identify the gear of the vehicle at the beginning of the upshift process, the target gear is used to identify the gear to be reached by the vehicle at the end of the upshift process, and the gear shifting progress is used to identify the completion progress of the upshift process;

[0045] The transmission ratio at the current moment is determined according to the transmission ratio of the target gear, the transmission ratio of the actual gear, and the gear shifting progress at the current moment.

[0046] In a possible implementation, the power system is a power-split multi-speed hybrid power system.

[0047] In another aspect, the present application provides a computer device, comprising:

[0048] Memory for storing computer programs;

[0049] A processor is used to implement the steps of the control method for preventing engine reverse rotation as described above when executing the computer program.

[0050] On the other hand, the present application provides a computer-readable medium having a computer program stored thereon, and when the computer program is processed and executed, the steps of the control method for preventing engine reversal as described above are implemented.

[0051] It can be seen that this application has the following beneficial effects:

[0052] The present application provides a control method for preventing engine reversal. First, the gear state of the vehicle is obtained. Then, when it is determined that the vehicle is in the process of upshifting, the speed reduction rate of the motor at the previous moment and the speed ratio of the input shaft and the output shaft of the power system at the current moment are obtained. In the process of upshifting, the transmission ratio decreases and the speed of the motor will drop rapidly. The speed reduction rate of the motor can directly reflect the speed of the motor speed reduction. However, due to the coupling structure of the engine and the motor in the traditional system, when the speed of the motor drops too fast, the relative balance between the engine and the motor will be broken, resulting in the dragging of the engine to reverse. According to different speed ratios and different speed reduction rates of the motor at the previous moment, this scheme pre-calibrates the speed reduction rate at the current moment that will not cause the engine to reverse according to experience, and constructs a relationship model in advance. Then, during the upshifting process, according to the actual speed reduction rate of the motor at the previous moment and the speed ratio at the current moment, the speed reduction rate at the current moment is obtained according to the pre-constructed relationship model, thereby adjusting the speed reduction rate of the motor at the current moment so that its maximum is the speed reduction rate. Therefore, in order to deal with the working conditions where the engine may reverse due to the rapid drop in motor speed during the upshift process, the motor speed reduction rate can be controlled in time, so that during the upshift process, the demand for motor speed reduction is met and the speed reduction rate can be made smoother, so as to avoid the situation where the motor speed drops too quickly and causes the engine to reverse, thereby achieving a better anti-reversal effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 A flow chart of a control method for preventing engine reversal provided in an embodiment of the present application;

[0054] Figure 2 A schematic diagram of the structure of a power split multi-speed hybrid power system provided in an embodiment of the present application;

[0055] Figure 3A schematic diagram of determining the speed reduction rate of a motor at the current moment provided in an embodiment of the present application;

[0056] Figure 4 A schematic diagram of a method for adjusting motor torque provided in an embodiment of the present application;

[0057] Figure 5 A schematic diagram of determining the torque reduction rate of a motor at the current moment provided in an embodiment of the present application;

[0058] Figure 6 A schematic diagram of the identification and control of an engine reversal condition provided in an embodiment of the present application;

[0059] Figure 7 A schematic diagram of a control device for preventing engine reverse rotation provided in an embodiment of the present application. DETAILED DESCRIPTION

[0060] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0061] As described in the background technology, in the related art, by monitoring the speed of the motor, the target torque required when the engine does not reverse can be calculated by the PID controller, and the motor can be controlled to output, but the PID controller has a slow response speed and low calculation accuracy. When the vehicle's driving conditions change rapidly, the effect of preventing the engine from reversing is not good. Especially in the oil-electric hybrid system, the engine and the motor are coupled to drive the vehicle together. During the vehicle upshift process, the PID controller cannot respond quickly to the situation where the engine reverses due to the vehicle's too fast gear shifting process.

[0062] Therefore, the present application provides a method for preventing engine reversal, which can pre-identify the working conditions where the engine reversal occurs, and by obtaining the gear state of the vehicle, when it is determined that the vehicle is in the process of upshifting, by limiting the speed decrease rate of the motor at the current moment, the speed decrease rate of the motor is made more gradual, thereby avoiding the situation where the engine reversal is caused by the motor speed decreasing too quickly, thereby achieving a better anti-reversal effect.

[0063] See also Figure 1 As shown, it is a flow chart of a control method for preventing engine reversal provided in an embodiment of the present application. In this embodiment, it can be executed by a control system as an example.

[0064] S101: Acquire the gear status of the vehicle.

[0065] The gear state of a vehicle refers to the state of the gear of the vehicle during driving. For example, the gear state of a vehicle includes gear, neutral and shifting. The vehicle control system can obtain the gear information sent by the transmission controller through the controller area network (CAN) bus to determine the gear state of the vehicle.

[0066] S102: If the gear position is in the process of upshifting, the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment are obtained.

[0067] The upshift process refers to the state in which the vehicle's gear is switched from a low gear to a high gear during driving. The transmission ratio is the speed ratio between the input shaft and the output shaft of the power system, where the power system refers to the system that converts fuel into mechanical energy to drive the vehicle.

[0068] The speed drop rate is the speed drop rate of the motor speed per unit time. The control system can monitor the motor speed information in real time, or sample the speed information through a fixed sampling period. The speed at different times represents the motor speed obtained in different sampling periods.

[0069] The control system can obtain the instantaneous speed of the motor in the first two sampling cycles and the instantaneous speed of the motor in the last sampling cycle through the speed sensor, and then obtain the speed reduction rate of the motor at the last moment according to the sampling cycle time. For example, the speed of the motor in the first two sampling cycles is m rpm, the speed of the last sampling cycle is n rpm, and the time of one cycle is 1 millisecond. Then, the speed reduction rate of the motor at the last moment obtained by the control system is (mn) / 0.1 rpm.

[0070] As the upshift process progresses, the transmission ratio is continuously reduced. The transmission ratio at the current moment can be calibrated based on experience, such as dividing the shift process into N cycles and setting the same transmission ratio in different cycles, or it can be calculated based on the actual shift progress of the shift process.

[0071] In a possible implementation, the transmission ratio at the current moment is obtained in the following manner:

[0072] Obtain the transmission ratio of the target gear, the transmission ratio of the initial gear, and the gear shifting progress at the current moment, wherein the initial gear is used to identify the gear position of the vehicle at the beginning of the upshift process, the target gear is used to identify the gear position to be reached by the vehicle at the end of the upshift process, and the gear shifting progress is used to identify the completion progress of the upshift process;

[0073] The transmission ratio at the current moment is determined according to the transmission ratio of the target gear, the transmission ratio of the actual gear, and the gear shifting progress at the current moment.

[0074] Specifically, the vehicle has corresponding transmission ratios at different gears. According to the power system used by the vehicle, the control system can directly obtain the transmission ratio of the gear in which the vehicle is at the beginning of the upshift process and the transmission ratio of the gear to be reached by the vehicle at the end of the upshift process. The gear shift process is expressed in the form of a percentage. In the actual gear shift process, it can be determined in combination with the engagement state of the clutch inside the gearbox. Then, the transmission ratio at the current moment can be determined in combination with the transmission ratios of different gears before and after the upshift and the gear shift process at the current moment.

[0075] Therefore, through this method, the transmission ratio at the current moment and the corresponding speed reduction rate of the motor at the current moment can be obtained more accurately, thereby improving the reliability of preventing the engine from reversing.

[0076] In the embodiment of the present application, the power system is powered by an engine and a motor, that is, a hybrid power system.

[0077] In one possible implementation, the power system is a power-split multi-speed hybrid power system.

[0078] See also Figure 2 As shown, it is a schematic diagram of the structure of a power split multi-speed hybrid power system provided in an embodiment of the present application. The power system includes a drive motor, a generator, an engine, a planetary gear, a power battery and a gearbox. Among them, the engine 1 is connected to the planet carrier 4 of the P1 planetary gear, the generator 2 is connected to the sun gear 5 of the P1 planetary gear, the ring gear 3 of the P1 planetary gear outputs power and is connected to the drive motor 6 and the gearbox input shaft 7, and the gearbox output shaft 9 is connected to the wheel end. The power battery 10 supplies power to the drive motor 6 and the generator 2, and the two motors can also charge the power battery.

[0079] During the vehicle's upshifting process, the structure of the transmission components inside the gearbox switches from a small gear to a large gear, and the transmission ratio of the power system will be reduced. Due to the fast gear shifting speed, the speed of the motor will drop rapidly when the vehicle's driving speed remains unchanged, which may cause the engine to reverse.

[0080] Combined with the structure of the power-split multi-speed hybrid system, we can analyze the working condition in which the engine reverses when the motor speed drops too quickly due to the coupling between the motor and the engine in the hybrid system. This allows us to take corresponding measures based on the vehicle's driving status to avoid the engine's reversal from the source.

[0081] S103: Determine a target speed reduction rate according to the current transmission ratio and the speed reduction rate of the motor at the previous moment and based on a pre-built speed relationship model.

[0082] The speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, wherein the target speed reduction rate is used to identify the speed reduction rate that will not cause engine reversal at the current moment.

[0083] During the upshift process, as the transmission ratio decreases at different times, the motor speed will decrease. In order to prevent the motor speed from decreasing too quickly, the current speed decrease rate is limited by the speed decrease rate at the previous moment to ensure that the motor speed at the current moment will not cause the engine to reverse. Therefore, after experiments on vehicles using the same power system, the motor speed decrease rate at the current moment was calibrated according to the transmission ratio at the current moment and the speed decrease rate at the previous moment, and a speed relationship model was pre-constructed.

[0084] The control system can directly search for the corresponding target speed reduction rate in the speed relationship model through the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, and use it as the speed reduction rate of the motor at the current moment.

[0085] S104: Control the motor's current speed reduction rate to a maximum of the target speed reduction rate.

[0086] When the speed reduction rate of the motor at the current moment is greater than the target speed reduction rate, it means that the speed reduction speed of the motor is faster than the speed reduction speed of the motor determined based on experience, and it is very likely that the conditions for reversing the engine have been met.

[0087] The vehicle control system can control the speed reduction rate of the motor at the current moment by adjusting the output torque at the current moment or directly adjusting the speed.

[0088] As an example, in the process of shifting the vehicle from 1st gear to 2nd gear, the motor speed needs to be reduced from m rpm to n rpm. The speed sampling period is 0.1 seconds. The speed reduction rate at the current moment is determined to be a by looking up the table. The control system controls the motor's maximum speed reduction rate at the current moment to be a. The speed has dropped by a*0.1 rpm at the current moment. If mn is greater than a*0.1, it means that the gear shifting process has not been completed. The speed reduction rate at the next moment is determined by looking up the table and the speed reduction rate of the motor is adjusted.

[0089] refer to Figure 3 As shown, it is a schematic diagram of determining the speed reduction rate of the motor at the current moment provided by an embodiment of the present application, and the schematic diagram is described below:

[0090] The transmission ratio at the current moment can be obtained by subtracting the product of the current gear shift process and the transmission ratio of the initial gear from 1, and then adding the product of the current gear shift process and the transmission ratio of the target gear. Based on this, the speed reduction rate of the motor at the previous moment can be obtained based on the pre-built speed relationship model.

[0091] Therefore, for the working condition in which the engine may reverse due to the rapid drop in motor speed during the upshift process, the working condition can be pre-identified based on the gear state of the vehicle, and the target speed drop rate of the motor at the current moment can be obtained through the pre-constructed speed relationship model, so as to timely control the speed drop rate of the motor, so that during the upshift process, the demand for motor speed reduction is met and the speed reduction rate can be made smoother, so as to avoid the situation in which the motor speed drops too quickly and causes the engine to reverse, thereby achieving a better anti-reversal effect.

[0092] In a possible implementation, the control system may further perform the following steps:

[0093] S201: Obtain the state of the engine.

[0094] The gear state of the engine refers to the state of the engine running during the vehicle's driving. For example, the engine state can be in the process of engine shutdown, engine shutdown, and engine working. The engine shutdown means that the vehicle is in a pure electric drive state. The vehicle's control system can obtain the engine state through the CAN bus.

[0095] S202: If the engine is in a shutdown state, obtain the torque after the motor is compensated.

[0096] When the engine is stopped, the inertia of the internal components will cause the engine torque to fluctuate up and down. To offset the torque fluctuation caused by the engine shutdown, the motor will increase the compensation torque. When the engine is stopped, the control system can obtain the motor compensated torque through the torque sensor.

[0097] S203: If the torque of the motor after compensation is negative torque, the transmission torque transmitted from the engine to the motor is obtained.

[0098] Negative torque is torque that is opposite to the working direction of the power system. The compensation torque of the motor can be positive or negative. If the motor compensates for a large negative torque, the torque after the motor compensation is negative torque, and the control system obtains the transmission torque transmitted from the engine to the motor.

[0099] Specifically, the control system can obtain the output torque of the engine through the sensor, and determine the transmission torque transmitted to the motor through the proportional coefficient of the torque transmitted from the engine to the motor.

[0100] As an example, in a power-split multi-speed hybrid system, the output torque of the engine is a, and the proportional coefficient of the torque on the planetary carrier converted to the torque on the ring gear is r, that is, the proportional coefficient of the torque transmitted to the motor by the output torque of the engine. Then the transmission torque transmitted to the motor is a*r.

[0101] S204: If the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero, the magnitude of the compensated torque of the motor is reduced by at least the difference.

[0102] If the size of the compensated negative torque is larger than the size of the transmission torque, the motor may drag the engine into reverse rotation. At this time, the control system obtains the difference between the size of the compensated torque and the size of the transmission torque, and uses the difference as a correction value to adjust the motor's compensated torque, reducing the size of the motor's compensated torque by at least the difference, so that the size of the compensated negative torque is not larger than the size of the transmission torque, thereby preventing the engine from reversing.

[0103] As an example, if the magnitude of the transmission torque transmitted from the engine to the motor is |a*r|, the magnitude of the torque after motor compensation is |b|, if |b|-|a*r| is c, and c is greater than 0, then the magnitude of the torque after motor compensation |b| is reduced by at least c.

[0104] As another example, in a power split multi-speed hybrid system, the ratio coefficient r of the torque transmitted from the engine output torque to the motor torque is a negative value, see Figure 4 As shown, it is a schematic diagram of a method for adjusting motor torque provided by the present application for a power split multi-speed hybrid system, wherein x in |x| represents an input value. The schematic diagram can be represented by the following formula:

[0105] Trq_TMCmp=|Min(Trq_TM-Trq_Eng*r, 0)|+Trq_TM

[0106] Among them, Trq_TM is the torque after motor compensation, Trq_Eng is the output torque of the engine, and Trq_TMCmp is the adjusted motor torque.

[0107] Therefore, by obtaining the state of the engine, when it is determined that the engine is in the shutdown process, the engine torque oscillation causes the motor to compensate for a large negative torque, causing the engine to reverse. By timely adjusting the size of the negative torque after the motor compensation, the size of the negative torque after the motor compensation is made no larger than the size of the transmission torque transmitted from the engine to the motor, thereby avoiding the situation where the motor drags the engine backwards and effectively improving the effect of preventing the engine from reversing.

[0108] In a possible implementation, the control system may further perform the following steps:

[0109] S301: Obtain the state of the engine.

[0110] S302: If the engine is in a stopped state and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the last moment are obtained.

[0111] The torque drop rate at the last moment is the difference between the torque of the motor at the previous two moments and the torque of the motor at the last moment.

[0112] Energy recovery is the process of converting the kinetic energy of a vehicle into electrical energy during braking. During this process, the motor needs to charge the power battery, so the motor will apply a large negative torque in a short period of time. At this time, the balance of the power system is instantly destroyed, and there is a possibility that the motor will reverse the engine.

[0113] The required recovery torque is the negative torque that the motor needs to apply during the energy recovery process, and the actual recovery torque is the negative torque that has been applied. The control system function can obtain the required recovery torque through the brake pedal, and the actual recovery torque can be obtained according to the difference between the motor output torque before energy recovery and the current motor torque. The torque reduction rate at the previous moment can be obtained by the difference between the motor output torque at the previous two moments and the motor output torque at the previous moment.

[0114] S303: Determine a torque difference according to a difference between the required recovery torque and the actual recovery torque.

[0115] The control system recovers the torque based on the demand and the actual recovered torque, and the torque difference obtained is the negative torque that the motor needs to apply.

[0116] S304: Determine a target torque reduction rate according to the torque reduction rate and the torque difference at the previous moment and based on a pre-built torque relationship model.

[0117] The torque relationship model is used to identify the relationship between different torque reduction rates and different torque differences at the previous moment and different target torque reduction rates. The target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment.

[0118] After experiments on vehicles using the same power system, a torque relationship model was pre-constructed based on the torque drop rate and torque difference of the motor at the previous moment.

[0119] The control system searches for the corresponding torque reduction rate in the torque relationship model through the torque reduction rate of the motor at the previous moment and the torque difference, and regards it as the torque reduction rate of the motor at the current moment.

[0120] refer to Figure 5As shown, a schematic diagram of determining the torque reduction rate of the motor at the current moment provided in an embodiment of the present application is provided. According to the difference between the motor's required recovery torque and the current actual recovery torque, and the torque reduction rate of the motor at the previous moment, the torque reduction rate of the motor at the current moment can be obtained through a pre-established torque relationship model.

[0121] S305: Control the current torque reduction rate of the motor to be the maximum target torque reduction rate.

[0122] The vehicle control system can control the torque reduction rate of the motor at the current moment by adjusting the output torque at the current moment.

[0123] Therefore, during the energy recovery process, by controlling the torque decrease rate of the motor at the current moment and controlling the output torque of the motor, the torque change of the motor at different moments can be made smoother, thereby maintaining the relative balance between the motor and the engine and avoiding the situation where the motor generates a large negative torque in a short period of time, causing the engine to reverse.

[0124] See also Figure 6 , which is a schematic diagram of the identification and control of an engine reversal condition provided by the present application, and the working conditions that cause the engine reversal and the technical solution for preventing the engine reversal are described in detail in combination with the schematic diagram:

[0125] During the engine shutdown process, the engine torque oscillates, and the motor needs to increase torque compensation to offset the engine torque fluctuation. The motor may need to compensate for a large negative torque. The torque after motor compensation may be negative torque, and its magnitude may be greater than the magnitude of the torque transmitted from the engine to the motor, thereby causing the engine to reverse. The present application adjusts the torque after motor compensation by comparing the magnitude of the negative torque after motor compensation with the magnitude of the torque transmitted from the engine to the motor, so that its magnitude is not greater than the magnitude of the torque transmitted from the engine to the motor, thereby avoiding engine reversal.

[0126] When the vehicle shifting conflicts with the mode switching, the shifting operation takes precedence, so there will not be a situation where the upshifting and engine shutdown processes are carried out at the same time. If the vehicle is in the process of shifting, and it is judged by the gear position that it is in the process of upshifting, the power demand required by the vehicle is relatively large at this time, and it will not be in the process of engine shutdown at the same time. In this case, because the clutch inside the gearbox engages too quickly when upshifting, when the vehicle speed remains unchanged, as the transmission ratio decreases, there is a situation where the motor speed drops rapidly and drags the engine in reverse. Based on the pre-constructed speed relationship model, the present application uses the speed drop rate of the motor at the previous moment and the transmission ratio at the current moment to obtain the speed drop rate of the motor at the current moment that will not cause the engine to reverse, so as to smooth the process of the motor speed drop and avoid the reversal of the engine.

[0127] When the engine is stopped, the vehicle is in a pure motor-driven state. If an emergency braking condition occurs at this time, the vehicle will recover energy to charge the motor to the power battery. The motor will generate a large negative torque in a short period of time, which may destroy the mutual balance between the engine and the motor in the power system and cause the engine to reverse. The present application controls the speed of torque recovery by adjusting the torque drop rate of the motor at different times to avoid the situation where the motor generates a large negative torque in a short period of time, thereby avoiding the reversal of the engine.

[0128] Based on a control method for preventing engine reversal provided in the above embodiment, an embodiment of the present application further provides a control device for preventing engine reversal, which is described in detail below in conjunction with the accompanying drawings.

[0129] refer to Figure 7 , which is a schematic diagram of a control device for preventing engine reversal provided in an embodiment of the present application, the device 700 includes an acquisition unit 701, a determination unit 702, and a control unit 703:

[0130] The acquisition unit 701 is used to acquire the gear status of the vehicle;

[0131] The acquisition unit 701 is further used to acquire the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment if the gear state is in the process of upshifting. The speed reduction rate is the speed reduction rate of the motor speed per unit time. The transmission ratio is the speed ratio between the input shaft and the output shaft of the power system. The power system is powered by the engine and the motor.

[0132] The determination unit 702 is used to determine the target speed reduction rate according to the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, based on a pre-constructed speed relationship model, wherein the speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, and the target speed reduction rate is used to identify the speed reduction rate that will not cause the engine to reverse at the current moment;

[0133] The control unit 703 is used to control the motor's current speed reduction rate to be at most a target speed reduction rate.

[0134] Therefore, for the working condition in which the engine may reverse due to the rapid drop in motor speed during the upshift process, the working condition can be pre-identified based on the gear state of the vehicle, and the target speed drop rate of the motor at the current moment can be obtained through the pre-constructed speed relationship model, so as to timely control the speed drop rate of the motor, so that during the upshift process, the demand for motor speed reduction is met and the speed reduction rate can be made smoother, so as to avoid the situation in which the motor speed drops too quickly and causes the engine to reverse, thereby achieving a better anti-reversal effect.

[0135] In a possible implementation, the acquiring unit is further configured to:

[0136] Obtaining the state of the engine;

[0137] If the state of the engine is during shutdown, obtaining the torque after motor compensation;

[0138] If the torque of the motor after compensation is a negative torque, the transmission torque transmitted from the engine to the motor is obtained, wherein the negative torque is a torque opposite to the working direction of the power system;

[0139] The control unit is further configured to reduce the magnitude of the motor's compensated torque by at least the difference if the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero.

[0140] In a possible implementation, the acquiring unit is further configured to:

[0141] Obtaining the state of the engine;

[0142] If the state of the engine is stopped and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the previous moment are obtained, where the torque reduction rate is the difference between the torque of the motor at the previous two moments and the torque of the motor at the previous moment;

[0143] The determining unit is further configured to determine the torque difference according to the difference between the required recovery torque and the actual recovery torque;

[0144] The determining unit is further used to determine a target torque reduction rate according to the torque reduction rate at the previous moment and the torque difference value based on a pre-constructed torque relationship model, wherein the torque relationship model is used to identify the relationship between different torque reduction rates at the previous moment and different torque differences and different target torque reduction rates, and the target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment;

[0145] The control unit is further configured to control the torque reduction rate of the motor at a current moment to be at most the target torque reduction rate.

[0146] In a possible implementation, the transmission ratio at the current moment is obtained in the following manner:

[0147] Acquire the transmission ratio of the target gear, the transmission ratio of the initial gear, and the gear shifting progress at the current moment, wherein the initial gear is used to identify the gear of the vehicle at the beginning of the upshift process, the target gear is used to identify the gear to be reached by the vehicle at the end of the upshift process, and the gear shifting progress is used to identify the completion progress of the upshift process;

[0148] The transmission ratio at the current moment is determined according to the transmission ratio of the target gear, the transmission ratio of the actual gear, and the gear shifting progress at the current moment.

[0149] Therefore, through this method, the transmission ratio at the current moment and the corresponding speed reduction rate of the motor at the current moment can be obtained more accurately, thereby improving the reliability of preventing the engine from reversing.

[0150] In one possible implementation, the power system is a power-split multi-speed hybrid power system.

[0151] Combined with the structure of the power-split multi-speed hybrid system, we can analyze the working condition in which the engine reverses when the motor speed drops too quickly due to the coupling between the motor and the engine in the hybrid system. This allows us to take corresponding measures based on the vehicle's driving status to avoid the engine's reversal from the source.

[0152] Based on the above embodiments, an embodiment of the present application provides a computer device, including:

[0153] Memory for storing computer programs;

[0154] A processor is used to implement the steps of the control method for preventing engine reverse rotation as described above when executing the computer program.

[0155] On the basis of the above-mentioned embodiment, the embodiment of the present application further provides a computer-readable medium, on which a computer program is stored, and when the computer program is processed and executed, the steps of the control method for preventing engine reversal as mentioned above are implemented.

[0156] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other. For the system or device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0157] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A control method for preventing engine reverse rotation, characterized in that: The method comprises: Get the gear status of the vehicle; If the gear state is in the process of upshifting, the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment are obtained, wherein the speed reduction rate is the speed reduction rate of the motor speed per unit time, and the transmission ratio is the speed ratio between the input shaft and the output shaft of the power system, and the power system is powered by the engine and the motor; According to the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, a target speed reduction rate is determined based on a pre-constructed speed relationship model, wherein the speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, and the target speed reduction rate is used to identify the speed reduction rate that will not cause engine reversal at the current moment; The speed reduction rate of the motor at the current moment is controlled to be at most the target speed reduction rate.

2. The method according to claim 1, characterized in that The method further comprises: Obtaining the state of the engine; If the state of the engine is during shutdown, obtaining the torque after motor compensation; If the torque of the motor after compensation is a negative torque, the transmission torque transmitted from the engine to the motor is obtained, wherein the negative torque is a torque opposite to the working direction of the power system; If the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero, the magnitude of the compensated torque of the motor is reduced by at least the difference.

3. The method according to claim 1, characterized in that The method further comprises: Obtaining the state of the engine; If the state of the engine is stopped and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the previous moment are obtained, where the torque reduction rate is the difference between the torque of the motor at the previous two moments and the torque of the motor at the previous moment; Determining the torque difference according to the difference between the required recovery torque and the actual recovery torque; According to the torque reduction rate at the previous moment and the torque difference, a target torque reduction rate is determined based on a pre-constructed torque relationship model, wherein the torque relationship model is used to identify the relationship between different torque reduction rates at the previous moment and different torque differences and different target torque reduction rates, and the target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment; The torque reduction rate of the motor at the current moment is controlled to be at most the target torque reduction rate.

4. The method according to claim 1, characterized in that: The transmission ratio at the current moment is obtained by: Acquire the transmission ratio of the target gear, the transmission ratio of the initial gear, and the gear shifting progress at the current moment, wherein the initial gear is used to identify the gear of the vehicle at the beginning of the upshift process, the target gear is used to identify the gear to be reached by the vehicle at the end of the upshift process, and the gear shifting progress is used to identify the completion progress of the upshift process; The transmission ratio at the current moment is determined according to the transmission ratio of the target gear, the transmission ratio of the actual gear, and the gear shifting progress at the current moment.

5. The method according to claim 1, characterized in that The power system is a power-split multi-speed hybrid power system.

6. A control device for preventing engine reverse rotation, characterized in that: The device comprises an acquisition unit, a determination unit and a control unit: The acquisition unit is used to acquire the gear status of the vehicle; The acquisition unit is further used to acquire the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment if the gear state is in the process of upshifting, wherein the speed reduction rate is the speed reduction rate of the motor speed per unit time, and the transmission ratio is the speed ratio between the input shaft and the output shaft of the power system, wherein the power system is powered by the engine and the motor; The determination unit is used to determine the target speed reduction rate according to the transmission ratio at the current moment and the speed reduction rate of the motor at the previous moment, based on a pre-constructed speed relationship model, wherein the speed relationship model is used to identify the relationship between different transmission ratios and different speed reduction rates at the previous moment and different target speed reduction rates, and the target speed reduction rate is used to identify the speed reduction rate that will not cause the engine to reverse at the current moment; The control unit is used to control the speed reduction rate of the motor at a current moment to be at most the target speed reduction rate.

7. The device according to claim 6, characterized in that The acquisition unit is also used for: Obtaining the state of the engine; If the state of the engine is during shutdown, obtaining the torque after motor compensation; If the torque of the motor after compensation is a negative torque, the transmission torque transmitted from the engine to the motor is obtained, wherein the negative torque is a torque opposite to the working direction of the power system; The control unit is further configured to reduce the magnitude of the motor's compensated torque by at least the difference if the difference between the magnitude of the compensated torque and the magnitude of the transmission torque is greater than zero.

8. The device according to claim 6, characterized in that The acquisition unit is also used for: Obtaining the state of the engine; If the state of the engine is stopped and an energy recovery signal of the vehicle is received, the required recovery torque, the actual recovery torque, and the torque reduction rate at the previous moment are obtained, where the torque reduction rate is the difference between the torque of the motor at the previous two moments and the torque of the motor at the previous moment; The determining unit is further configured to determine the torque difference according to the difference between the required recovery torque and the actual recovery torque; The determining unit is further used to determine a target torque reduction rate according to the torque reduction rate at the previous moment and the torque difference value based on a pre-constructed torque relationship model, wherein the torque relationship model is used to identify the relationship between different torque reduction rates at the previous moment and different torque differences and different target torque reduction rates, and the target torque reduction rate is used to identify the torque reduction rate that will not cause engine reversal at the current moment; The control unit is further configured to control the torque reduction rate of the motor at a current moment to be at most the target torque reduction rate.

9. A computer device, characterized in that: The computer device comprises a processor and a memory: The memory is used to store computer programs; The processor is configured to execute the method according to any one of claims 1 to 5 according to the computer program.

10. A computer-readable medium, characterized in that The computer-readable medium is used to store a computer program, and when the computer program is executed by a computer device, the method according to any one of claims 1 to 5 is implemented.

Images