WO2023070603A1

WO2023070603A1 - Engine torque control method and apparatus for hybrid vehicle

Info

Publication number: WO2023070603A1
Application number: PCT/CN2021/127725
Authority: WO
Inventors: 莫延召; 卢刚
Original assignee: 舍弗勒技术股份两合公司
Priority date: 2021-10-29
Filing date: 2021-10-29
Publication date: 2023-05-04

Abstract

An engine torque control method for a hybrid vehicle, specifically comprising: working condition identification: when an accelerator pedal which is stepped on is released, identifying a quick torque trigger condition indicating that a torque reduction capability of a generator is inadequate; quick torque intervention: when the quick torque trigger condition is satisfied, intervening the actual torque of an engine by using a target quick torque value by means of engine quick torsion; and quick torque exit: when a quick torque exit condition is satisfied, stopping intervention of the engine quick torsion. The engine torque control method can improve the engine response characteristics of the hybrid vehicle. The present invention further relates to an engine torque control apparatus for a hybrid vehicle.

Description

Engine torque control method and control device for hybrid vehicle

technical field

The invention relates to the technical field of hybrid vehicles. In particular, the present invention relates to an engine torque control method and control device for a hybrid vehicle.

Background technique

Under the background of increasingly prominent energy and environmental issues, new energy vehicles are getting more and more attention. A hybrid vehicle with a layout of P1+P3 is a type of new energy vehicle frequently used at present, and FIG. 1 shows a schematic diagram of a power system of a hybrid vehicle with this layout. Among them, the generator GM is connected to the rear end of the engine E (internal combustion engine, ICE) and the front end of the clutch K0, which is the position P1; the driving motor DM is connected to the rear end of the transmission, which is the position P3. When the clutch K0 is disconnected, the driving motor DM can directly drive the vehicle, and the generator GM can recover the torque of the engine E to generate electricity. When the clutch K0 is closed, the engine E and the generator GM drive the vehicle together with the drive motor DM via the clutch K0.

For a hybrid vehicle, when the driver steps on the accelerator, the driver's demand for torque increases continuously, the battery is discharged, and the torque and speed of the engine E both rise. When the accelerator is released, the driver's demand torque will first drop to zero and then become a negative value (generator GM performs energy recovery). At this time, the speed and torque of the engine E need to be reduced, and the motor is expected to output negative torque to participate in the speed reduction. In this case, the torque of the generator GM is negative and the speed is positive. At this time, the power of the generator GM is negative, and the battery is in a charged state. Under normal conditions, the battery has a lot of charging power, which can reduce the torque and speed of the engine E very quickly. However, some special circumstances may lead to limited charging power of the battery, for example, the remaining power of the battery is too high or the environmental conditions affect the charging power of the battery, etc., the generator GM cannot output enough negative torque to offset the torque of the engine E, so that the engine reaches a high level. The speed is very loud. This problem is common, especially when the charging power of the battery is limited in a low temperature environment, the problem is more serious.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to provide an engine torque control method that improves the engine response characteristics of a hybrid vehicle.

The above technical problems are solved by an engine torque control method for a hybrid vehicle according to the present invention. The hybrid vehicle includes a power system, the power system includes a generator introduced into the power system between the engine and the clutch, and a drive motor introduced into the power system at the rear end of the transmission, and the power system is controlled by the accelerator pedal of the hybrid vehicle. Wherein, the engine torque control method includes:

Working condition identification, wherein, when the depressed accelerator pedal is released, identify the trigger condition of fast torque indicating that the torque reduction capability of the generator is insufficient;

torque intervention, wherein when the torque trigger condition is met, engine torque is used at a target torque value to intervene on the actual torque of the engine; and

Quick twist exit, wherein, when the quick twist exit condition is satisfied, the intervention of the engine quick twist is stopped.

According to a preferred embodiment of the present invention, the fast twist trigger condition can be that the maximum value of the absolute value of the negative torque that the generator allows to output to the engine is less than the current actual torque of the engine, and the absolute value of the negative torque that the generator allows to output to the engine The maximum value is equal to the product of the current maximum allowable absolute value of the output negative torque of the generator and the speed ratio of the engine to the generator.

According to another preferred embodiment of the present invention, the target fast torque value may be the maximum value of the absolute value of the negative torque that the generator is allowed to output to the engine (E) and the target torque of the slow torque request of the engine minus a predetermined value respectively the later smaller. Preferably, the predetermined value may be 0.3-05.

According to another preferred embodiment of the present invention, the fast-twisting exit condition may be that the difference between the maximum torque of the engine in response to the slow-twisting request and the maximum absolute value of the negative torque that the generator is allowed to output to the engine is less than a predetermined difference.

According to another preferred embodiment of the present invention, the step of fast twist intervention may include activating a flag bit when the fast twist trigger condition is satisfied; and the step of fast twist exit may include resetting the flag bit when the fast twist exit condition is met.

According to another preferred embodiment of the present invention, the engine torque control method can be executed by a vehicle controller of a hybrid electric vehicle.

The above-mentioned technical problems are solved by an engine torque control device for a hybrid vehicle according to the present invention. The hybrid vehicle includes a power system, the power system includes a generator introduced into the power system between the engine and the clutch, and a drive motor introduced into the power system at the rear end of the transmission, and the power system is controlled by the accelerator pedal of the hybrid vehicle. Wherein, the engine torque control device includes:

An operating condition identification module configured to identify a fast torque trigger condition indicating insufficient torque reduction capability of the generator when the depressed accelerator pedal is released;

a torque intervention module configured to use engine torque at a target torque value to intervene on the actual torque of the engine when the torque trigger condition is met; and

A snap-out module configured to stop engine snap-out intervention when snap-out conditions are met.

According to a preferred embodiment of the present invention, the working condition identification module can be configured as:

Comparing the maximum value of the absolute value of the negative torque that the generator allows to output to the engine and the current actual torque of the engine;

When the maximum value of the absolute value of the negative torque that the generator is allowed to output to the engine is smaller than the current actual torque of the engine, it is identified as satisfying the triggering condition for fast torque.

According to another preferred embodiment of the present invention, the fast-twist intervention module may include a determination unit configured to determine the maximum value of the absolute value of the negative torque that the generator is allowed to output to the engine and the target torque of the slow-twist request of the engine, respectively The smaller one after subtracting the predetermined value is determined as the target fast twist value.

According to another preferred embodiment of the present invention, the quick twist withdrawal module can be configured as:

calculating the difference between the maximum torque of the engine in response to the creep request and the maximum absolute value of the negative torque the generator is allowed to output to the engine, and comparing the difference with a predetermined difference;

When the difference is smaller than the predetermined difference, it is identified as satisfying the fast twist exit condition.

According to another preferred embodiment of the present invention, the working condition identification module may include an activation unit configured to activate the flag bit when the quick twist trigger condition is satisfied; and the quick twist exit module may include a reset unit configured to The flag bit is reset when the quick twist exit condition is satisfied.

Description of drawings

Further describe the present invention below in conjunction with accompanying drawing. Elements with the same function are denoted by the same reference numerals in the figures. in:

1 shows a schematic diagram of a power system applying an engine torque control method according to an exemplary embodiment of the present invention;

FIG. 2 shows a flowchart of steps of an engine torque control method according to an exemplary embodiment of the present invention; and

3a and 3b show response curves of an engine torque control method according to the prior art and an engine torque control method according to an exemplary embodiment of the present invention, respectively.

Detailed ways

The specific implementations of the engine torque control method and control device for a hybrid vehicle according to the present invention will be described below with reference to the accompanying drawings. The following detailed description and drawings are used to illustrate the principles of the present invention. The present invention is not limited to the described preferred embodiments, and the protection scope of the present invention is defined by the claims.

According to an embodiment of the present invention, an engine torque control method for a hybrid vehicle is provided. FIG. 1 shows a schematic diagram of the power system of the hybrid vehicle. As shown in FIG. 1 , the power system includes an engine E, a generator GM, a clutch K0, a transmission T, a differential D, a drive motor DM, a battery, wheels W, and the like. The generator GM is introduced into the power system at the position P1 between the engine E and the clutch K0, the generator GM can recover the kinetic energy of the engine E to generate electricity, and can provide the generated electric energy to the battery. The battery can supply power to the drive motor DM. The drive motor DM is introduced into the power system at the P3 position at the rear end of the transmission, and can directly drive the wheels W. The powertrain is controlled by an accelerator pedal (not shown) of the hybrid vehicle.

In order to enable the engine to quickly reduce the torque and speed when the driver looses the accelerator, the following method is used to control the engine torque.

As shown in the step diagram of FIG. 2 , first, the working condition identification is performed in step S1 . Specifically, when the depressed accelerator pedal is released, a snap-twist trigger condition is identified that indicates insufficient torque reduction capability of the generator GM.

Here, the fast torque trigger condition indicating that the generator GM has insufficient torque reduction capability refers to the situation that the charging power of the battery is not enough to make the generator GM output enough negative torque to reduce the torque of the engine E. The fast torque trigger condition needs to be dynamically judged according to the current actual torque of the engine E and the negative torque that the generator GM can output to the engine E. Specifically, if the negative torque that the generator GM can output to the engine E can cover the current actual torque of the engine E, there is no need to start the engine quick twist, otherwise it is necessary to start the engine quick twist. Since the negative torque output from the generator GM to the engine E is a negative value and the actual torque of the engine E is a positive value, it means that the triggering condition for fast torque is the maximum value of the absolute value of the negative torque that the generator GM allows to output to the engine E is less than the current actual torque of engine E. Here, the maximum value of the absolute value of the generator GM allowable output negative torque to the engine E is equal to the product of the current maximum allowable absolute value of the output negative torque of the generator GM and the speed ratio of the engine E to the generator GM.

If in step S1 it is identified that the snap-twist trigger condition is satisfied, the control method will initiate step S2 for snap-twist intervention. In step S2, when the triggering condition of the fast torque is satisfied, the actual torque of the engine E is intervened by using the fast torque of the engine at the target fast torque value.

Preferably, in step S2, the flag bit may be activated when the fast twist trigger condition is satisfied, and then the fast twist intervention is started based on the activated flag bit. The flag bit here is a flag indicating the torque control mode of the engine E. The flag usually has two states of triggering and non-triggering, corresponding to the engine fast torque control mode controlled by the engine fire circuit and the engine slow torque control mode controlled by the engine air circuit. The activated flag corresponds to the engine quick torque control mode controlled by the engine fire circuit. After an intervention using engine torque, the engine E can quickly respond to the driver's torque demand and reduce torque and speed.

Preferably, the target fast torque value is the smaller of the maximum value of the absolute value of the negative torque allowed by the generator GM to be output to the engine E and the target torque of the slow torque request of the engine E minus a predetermined value respectively. The predetermined value here may be a small value, such as 0.3-05.

Next, in step S3, perform quick twisting and exit. Specifically, the quick twist does not need to be intervened all the time, and after the quick twist intervention is started, the engine quick twist intervention is stopped when the quick twist exit condition is met.

The quick-twist exit condition specifically means that when the current maximum air path torque of the engine E after the quick-twist intervention is close to the maximum absolute value of the negative torque that the generator GM allows to output to the engine E, the flag can be Bit is reset to the inactive state. The gas path torque of the engine E refers to the torque of the engine E in response to the slow torque request. That is to say, the fast torque exit condition is that the difference between the maximum torque of the engine E in response to the slow torque request and the maximum absolute value of the negative torque that the generator GM is allowed to output to the engine E is less than a predetermined difference. As long as the predetermined difference is selected to be small enough, it means that the two values are close enough when the fast twist exit condition is satisfied. At this time, the torque and rotational speed of the engine E can be basically controlled only by the output negative torque of the generator GM.

Preferably, the flag bit can be reset when the above fast-twisting exit condition is satisfied. Therefore, the flag bit that has been triggered is reset to the non-triggered state, so that the state of fast twist intervention ends. Thereafter, the engine E enters into the state of slow torque control again.

The above engine torque control method may be executed by a vehicle controller of a hybrid vehicle. Various data required to implement the control method can be obtained through various original sensors of the hybrid electric vehicle, so no additional components need to be added.

According to an embodiment of the present invention, an engine torque control device for a hybrid vehicle is also provided. The engine torque control device can correspondingly implement the above-mentioned engine torque control method, and is also applied to the power system of the hybrid vehicle shown in FIG. 1 . The control device may be composed of functional modules in the vehicle controller. The control device includes a working condition identification module, a quick twist intervention module and a quick twist withdrawal module.

The working condition identification module is used to execute step S1, which is configured to identify a quick twist trigger condition when the depressed accelerator pedal is released. Preferably, the working condition recognition module is configured to compare the maximum absolute value of the negative torque that the generator GM is allowed to output to the engine E with the current actual torque of the engine E, so as to determine whether the fast torque trigger condition is satisfied; When the maximum value of the absolute value of the negative torque to the engine E is smaller than the current actual torque of the engine E, it is identified as satisfying the triggering condition of fast torque. Preferably, the working condition identification module may further include an activation unit configured to activate the flag bit when the quick twist trigger condition is met.

The quick torque intervention module is used to execute step S2, which is configured to use the engine quick torque at a target quick torque value to intervene on the actual torque of the engine E when the quick torque trigger condition is met. Preferably, the quick twist intervention module may include a determination unit. The determining unit is configured to determine the smaller of the maximum value of the absolute value of the negative torque that the generator GM is allowed to output to the engine E and the target torque of the slow torque request of the engine E after subtracting predetermined values as the target fast torque value.

The fast-twisting exit module is used to execute step S3, which is configured to stop the intervention of the fast-twisting engine when the fast-twisting exit condition is met. Preferably, the fast-twist exit module can be configured to calculate the difference between the maximum torque of the engine E in response to the slow-twist request and the maximum value of the absolute value of the negative torque that the generator GM is allowed to output to the engine E, and compare the difference with a predetermined The differences are compared to determine whether the fast-twisting exit condition is satisfied; when the difference is less than a predetermined difference, it is recognized that the fast-twisting exit condition is met. Preferably, the fast-twist exit module may further include a reset unit configured to reset the flag bit when the fast-twist exit condition is met.

By comparing the response curve of the prior art of Fig. 3a with the response curve of the present invention of Fig. 3b, it can be seen that using the control method and control device according to the present invention, when the driver releases the accelerator pedal after depressing the accelerator pedal, The entire response process of the torque and speed of the engine E is very smooth, and there will be no jump in the engine speed, which not only improves the NVH (noise, vibration and harshness) performance of the engine, but also brings good driving experience to the driver. experience. In addition, this control method and control device can also accurately determine the working condition of the limited charging power of the battery, so as to prevent the battery from being damaged due to overcharging.

Although possible embodiments have been exemplarily described in the above description, it should be understood that there are still numerous variations of the embodiments through all known and otherwise readily conceivable combinations of technical features and implementations. Furthermore, it should be understood that the exemplary embodiment is merely an example, and such embodiment in no way limits the scope, application and configuration of the present invention. The foregoing description is more to provide technical guidance for the transformation of at least one exemplary embodiment, wherein various changes can be made as long as they do not depart from the scope of protection of the claims, especially with regard to the Changes in function and structure of components.

Table of reference signs

E engine

K0 Clutch

D Differential

DM drive motor

GM generator

T transmission

W wheel

Claims

An engine torque control method for a hybrid vehicle comprising a power system including a generator (GM) introduced into the power system between an engine (E) and a clutch (K0) And introducing the drive motor (DM) of the power system at the rear end of the transmission, the power system is controlled by the accelerator pedal of the hybrid vehicle, characterized in that,

The engine torque control method includes:

Working condition identification (S1), wherein, when the depressed accelerator pedal is released, identifying a fast torque trigger condition indicating that the torque reduction capability of the generator (GM) is insufficient;

fast torque intervention (S2), wherein, when the fast torque trigger condition is met, the engine fast torque is used at a target fast torque value to intervene on the actual torque of the engine (E); and

Quick twist exit (S3), wherein, when the quick twist exit condition is satisfied, the intervention of the engine quick twist is stopped.
The engine torque control method according to claim 1, characterized in that, the fast torque trigger condition is that the maximum value of the absolute value of the negative torque that the generator (GM) allows to output to the engine (E) is less than the specified the current actual torque of the engine (E).
The engine torque control method according to claim 2, characterized in that the target fast torque value is equal to the maximum value of the absolute value of the negative torque that the generator (GM) is allowed to output to the engine (E) The target torque of the slow torque request of the engine (E) is the smaller one after subtracting predetermined values respectively.
The engine torque control method according to claim 3, wherein the predetermined value is 0.3-05.
The engine torque control method according to claim 1, characterized in that the fast-twisting withdrawal condition is the maximum torque of the engine (E) in response to the slow-twisting request and the allowable output of the generator (GM) to the The difference between the maximum values of the absolute value of the negative torque of the engine (E) is smaller than a predetermined difference.
The engine torque control method according to claim 1, characterized in that the step of said quick twist intervention (S2) includes activating a flag when said quick twist trigger condition is met; and

The step of exiting from fast twisting (S3) includes resetting the flag bit when the conditions for exiting from fast twisting are satisfied.
The engine torque control method according to any one of claims 1 to 6, characterized in that the engine torque control method is executed by a vehicle controller of the hybrid electric vehicle.
An engine torque control device for a hybrid vehicle comprising a power system including a generator (GM) introduced into the power system between an engine (E) and a clutch (K0) And introducing the drive motor (DM) of the power system at the rear end of the transmission, the power system is controlled by the accelerator pedal of the hybrid vehicle, characterized in that,

The engine torque control device includes:

An operating condition identification module configured to identify a fast torque trigger condition indicating that the generator (GM) has insufficient torque reduction capability when the depressed accelerator pedal is released;

a fast torque intervention module configured to use engine fast torque at a target fast torque value to intervene on the actual torque of the engine (E) when the fast torque trigger condition is met; and

A snap-out module configured to stop engine snap-out intervention when snap-out conditions are met.
The engine torque control device according to claim 8, wherein the operating condition identification module is configured as:

Comparing the maximum value of the absolute value of the negative torque that the generator (GM) is allowed to output to the engine (E) with the current actual torque of the engine (E);

When the maximum value of the absolute value of the negative torque that the generator (GM) is allowed to output to the engine (E) is smaller than the current actual torque of the engine (E), it is identified as satisfying the triggering condition for fast torque.
The engine torque control device according to claim 9, characterized in that, the fast torque intervention module includes a determination unit configured to allow the output of the generator (GM) to the engine (E) The smaller of the maximum value of the absolute value of the negative torque and the target torque of the slow torque request of the engine (E) minus a predetermined value is determined as the target fast torque value.
The engine torque control device according to claim 8, characterized in that, the quick twist withdrawal module is configured as:

calculating the difference between the maximum torque of the engine (E) in response to the slow torque request and the maximum value of the absolute value of the negative torque that the generator (GM) is allowed to output to the engine (E), and calculating the difference compared with a predetermined difference;

When the difference is smaller than a predetermined difference, it is identified as satisfying the fast twist exit condition.
The engine torque control device according to any one of claims 8 to 11, wherein the working condition recognition module includes an activation unit configured to activate a flag when the fast torque trigger condition is satisfied ;and

The fast twist exit module includes a reset unit configured to reset the flag bit when the fast twist exit condition is met.