CN111605527A

CN111605527A - Brake control method, device and controller

Info

Publication number: CN111605527A
Application number: CN201910142102.XA
Authority: CN
Inventors: 王艳静; 谢明维; 易迪华; 梁海强; 代康伟
Original assignee: Beijing Electric Vehicle Co Ltd
Current assignee: Beijing Electric Vehicle Co Ltd
Priority date: 2019-02-26
Filing date: 2019-02-26
Publication date: 2020-09-01
Anticipated expiration: 2039-02-26
Also published as: CN111605527B

Abstract

The invention provides a brake control method, a brake control device and a controller, wherein the brake control method is applied to a distributed drive automobile comprising an electric power-assisted brake system, and comprises the following steps: acquiring required braking force, front axle electric brake recovery capacity and rear axle electric brake recovery capacity; determining a current braking mode according to the required braking force, the front axle electric braking recovery capacity, the rear axle electric braking recovery capacity and preset front axle-rear axle braking force distribution constraint; and distributing the braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake according to the braking mode and the required braking force. According to the embodiment of the invention, the current braking mode is determined by acquiring the required braking force, the front axle electric braking recovery capacity and the rear axle electric braking recovery capacity and combining the preset front axle-rear axle braking force distribution constraint, the braking force is reasonably distributed to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake, and the whole vehicle economy and the consistency of the deceleration process are realized.

Description

Brake control method, device and controller

Technical Field

The invention relates to the technical field of automobiles, in particular to a brake control method, a brake control device and a brake control controller.

Background

According to different layout forms of a power system, the electric automobile can be divided into two driving forms of centralized driving and distributed driving. The centralized driving power needs to be finally acted on wheels through a transmission, a transmission shaft, a differential mechanism, a half shaft and other components, the compatibility of an electric automobile and a traditional fuel oil vehicle is maintained to the maximum extent, and therefore the vehicle models launched by various large host factories at home and abroad at present adopt a centralized driving mode. However, the disadvantages of many transmission parts, low transmission efficiency and complex control in the centralized driving mode gradually appear, and the distributed driving mode cancels the transmission parts and directly installs the driving motor in the driving wheel. This design has great advantages in control, such as: four wheels can be directly driven or braked, and the torque of the four wheels can be freely distributed within an allowable range, so that various performances of the vehicle can be improved; the power of a single motor is correspondingly reduced, and the flexibility of the whole vehicle arrangement is improved; the motor response is rapid and accurate, and the system can be combined with a driving antiskid system, a braking antiskid system and the like to ensure that the vehicle is more stable and safer. The distributed drive electric vehicle has been the focus of the subsequent research on the electric vehicle due to the advantages.

The development trend of intellectualization and electromotion provides higher requirements and challenges for a brake system, and an electric power-assisted brake system is undoubtedly an optimal choice. The electric power-assisted brake system can adjust control parameters to change the power assistance size so as to obtain different pedal feelings. The electric power-assisted brake system can realize partial decoupling and complete decoupling between the brake pedal and the main cylinder, so that hydraulic brake and regenerative brake can work coordinately (namely serial brake energy recovery or coordinative distributed brake energy recovery), the economy of brake recovery is ensured, and the comfort of consistent pedal feel is kept. In addition, the electric power-assisted brake system has the capability of quickly building pressure and the capability of building pressure comfort, and can meet the requirements of auxiliary driving functions such as emergency braking, adaptive cruise control and the like.

There has been no relevant study on the brake control of a distributed drive vehicle including an electric power assisted brake system.

Disclosure of Invention

The technical problem to be solved by the embodiment of the invention is to provide a brake control method, a brake control device and a brake control controller, which are used for realizing the consistency of the whole vehicle economy and the deceleration process.

In order to solve the above technical problem, an embodiment of the present invention provides a brake control method applied to a distributed drive vehicle including an electric power assisted brake system, where the method includes:

acquiring required braking force, front axle electric brake recovery capacity and rear axle electric brake recovery capacity;

determining a current braking mode according to the required braking force, the front axle electric brake recovery capacity, the rear axle electric brake recovery capacity and preset front axle-rear axle braking force distribution constraint;

and distributing the braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake according to the braking mode and the required braking force.

Optionally, the braking mode includes: a pure electric-front axle electric braking mode, a pure electric-front and rear axle electric braking mode, an electro-hydraulic braking mode and a pure liquid braking mode;

the priority of the pure electric-front axle electric braking mode, the pure electric-front and rear axle electric braking mode, the electro-hydraulic braking mode and the pure liquid braking mode is reduced in sequence.

Optionally, the step of obtaining the required braking force, the front axle electric brake recovery capability and the rear axle electric brake recovery capability includes:

obtaining the travel of a brake pedal, the first recovery capacity of a front axle left wheel motor, the second recovery capacity of a front axle right wheel motor, the third recovery capacity of a rear axle left wheel motor and the fourth recovery capacity of a rear axle right wheel motor;

obtaining the required braking force according to the travel of the brake pedal;

obtaining the front axle electric brake recovery capacity according to the smaller of the first recovery capacity and the second recovery capacity;

and obtaining the rear axle electric brake recovery capacity according to the smaller of the third recovery capacity and the fourth recovery capacity.

Optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint includes:

when the required braking force is smaller than or equal to a first braking force and the required braking force is smaller than or equal to the front axle electric braking recovery capacity, determining that the current braking mode is the pure electric-front axle electric braking mode;

in the pure electric-front axle electric braking mode, the braking force of the front axle motor is equal to the required braking force, and the braking forces of the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake are all zero;

wherein the first braking force is the maximum value of the front axle braking force when the rear axle braking force in the preset front axle-rear axle braking force distribution constraint is equal to zero.

Optionally, when the electric braking capability of the front axle is less than or equal to the first braking force, the step of determining the current braking mode according to the required braking force, the electric braking recovery capability of the front axle, the electric braking recovery capability of the rear axle, and the preset front axle-rear axle braking force distribution constraint includes:

when the required braking force is larger than the front axle electric braking recovery capacity, the difference value between the required braking force and the front axle electric braking recovery capacity is smaller than or equal to the rear axle electric braking capacity, and the difference value between the required braking force and the front axle electric braking recovery capacity is smaller than or equal to a second braking force, determining that the current braking mode is the pure electric front and rear axle electric braking mode;

in the pure electric-front and rear axle electric braking mode, the braking force of the front axle motor is equal to the electric braking force of the front axle, the braking force of the rear axle motor is equal to the difference value between the required braking force and the electric braking force of the front axle, and the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake are both zero;

wherein the first braking force is the maximum value of the front axle braking force when the rear axle braking force in the preset front axle-rear axle braking force distribution constraint is equal to zero;

and the second braking force is the maximum value of the rear axle braking force corresponding to the situation that the front axle braking force is equal to the front axle electric braking capability in the preset front axle-rear axle braking force distribution constraint.

Optionally, when the electric braking capability of the front axle is greater than the first braking force, the step of determining the current braking mode according to the required braking force, the electric braking recovery capability of the front axle, the electric braking recovery capability of the rear axle, and the preset front axle-rear axle braking force distribution constraint includes:

when the required braking force is larger than the front axle electric braking recovery capacity, the difference between the required braking force and the front axle electric braking recovery capacity is smaller than or equal to the rear axle electric braking capacity, the difference between the required braking force and the front axle electric braking recovery capacity is smaller than or equal to a second braking force, and the difference between the required braking force and the front axle electric braking recovery capacity is larger than or equal to a third braking force, determining that the current braking mode is the pure electric-front and rear axle electric braking mode;

the second braking force is the maximum value of the rear axle braking force corresponding to the situation that the front axle braking force is equal to the front axle electric braking capability in the preset front axle-rear axle braking force distribution constraint;

and the third braking force is the minimum value of the front axle braking force corresponding to the situation that the rear axle braking force is equal to the second braking force in the preset front axle-rear axle braking force distribution constraint.

Optionally, the electro-hydraulic braking mode includes: a first electro-hydraulic braking mode and a second electro-hydraulic braking mode of front axle electric braking, front axle hydraulic braking and rear axle hydraulic braking;

determining a current braking mode according to the required braking force, the front axle electric brake recovery capacity, the rear axle electric brake recovery capacity and preset front axle-rear axle braking force distribution constraint, wherein the step of determining the current braking mode comprises the following steps:

when the situation that the pure electric-front axle electric braking mode or the pure electric-front and rear axle electric braking mode is not met and the front axle electric braking recovery capacity is larger than or equal to a first preset value is not met, determining that the current braking mode is the first electro-hydraulic braking mode;

in the first electro-hydraulic braking mode, the braking force of the front axle motor is equal to the first preset value, the braking force of the rear axle motor is zero, and the sum of the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake is a fifth braking force;

the first preset value is a difference value between a fourth braking force and the fifth braking force;

the fourth braking force is the maximum front axle braking force which can be achieved by the current required braking force under the preset front axle-rear axle braking force distribution constraint;

the fifth braking force is a difference between the required braking force and the fourth braking force.

Optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint further includes:

when the situation that the pure electric-front axle electric braking mode or the pure electric-front and rear axle electric braking mode is not met and the front axle electric braking recovery capacity is smaller than the first preset value is not met, determining that the current braking mode is the second electric-hydraulic braking mode;

in the second electro-hydraulic braking mode, the braking force of the front axle motor is equal to the electric braking recovery capacity of the front axle, the braking force of the rear axle motor is zero, and the sum of the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake is the difference value between the required braking force and the electric braking recovery capacity of the front axle.

Optionally, the electro-hydraulic braking mode includes: a third electro-hydraulic braking mode and a fourth electro-hydraulic braking mode of front axle hydraulic braking, rear axle hydraulic braking and rear axle electric braking;

when the front axle electric brake recovery capacity is zero and the rear axle electric brake recovery capacity is greater than or equal to a second preset value, determining that the current brake mode is the third electric hydraulic brake mode;

in the third electro-hydraulic braking mode, the braking force of the front axle motor is equal to zero, the braking force of the rear axle motor is equal to the electric braking capacity of the rear axle, and the sum of the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake is the difference between the required braking force and the electric braking recovery capacity of the rear axle;

the second preset value is a difference value of the sixth braking force and the seventh braking force;

the sixth braking force is the maximum rear axle braking force which can be reached by the current required braking force under the preset front axle-rear axle braking force distribution constraint; the difference value between the required braking force and the sixth braking force is an eighth braking force;

and the seventh braking force is the rear axle braking force corresponding to the situation that the front axle braking force on a preset pure hydraulic front and rear axle hydraulic distribution curve is the eighth braking force.

when the front axle electric brake recovery capacity is zero and the rear axle electric brake recovery capacity is smaller than the second preset value, determining that the current brake mode is the fourth electric hydraulic brake mode;

in the third electro-hydraulic braking mode, the braking force of the front axle motor is equal to zero, the braking force of the rear axle motor is equal to the second preset value, and the sum of the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake is the difference value between the required braking force and the second preset value.

when the front axle electric brake recovery capacity is equal to zero and the rear axle electric brake recovery capacity is equal to zero, determining that the current brake mode is the pure liquid brake mode;

in the pure liquid braking mode, the braking force of the front axle motor is equal to zero, the braking force of the rear axle motor is equal to zero, the sum of the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake is equal to the required braking force, and the braking forces of the front axle hydraulic brake and the rear axle hydraulic brake are distributed according to a preset pure hydraulic front and rear axle hydraulic distribution curve.

According to another aspect of the present invention, there is also provided a brake control apparatus for a distributed drive vehicle including an electric power assisted brake system, the apparatus including:

the acquisition module is used for acquiring required braking force, front axle electric brake recovery capacity and rear axle electric brake recovery capacity;

the determining module is used for determining a current braking mode according to the required braking force, the front axle electric brake recovery capacity, the rear axle electric brake recovery capacity and preset front axle-rear axle braking force distribution constraint;

and the control module is used for distributing braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake according to the braking mode and the required braking force.

According to another aspect of the present invention, there is also provided a controller including a processor, a memory, and a computer program stored on the memory and executable on the processor, the computer program implementing the steps of the braking control method as described above when executed by the processor.

According to another aspect of the present invention, the embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, which when executed by a processor implements the steps of the braking control method as described above.

Compared with the prior art, the brake control method, the brake control device and the brake control controller provided by the embodiment of the invention at least have the following beneficial effects: according to the embodiment of the invention, the current braking mode is determined by acquiring the required braking force, the front axle electric braking recovery capacity and the rear axle electric braking recovery capacity and combining the preset front axle-rear axle braking force distribution constraint, and the braking force is reasonably distributed to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake, so that the whole vehicle economy and the consistency of the deceleration process are realized.

Drawings

FIG. 1 is a flow chart of a brake control method according to an embodiment of the present invention;

FIG. 2 is a schematic structural diagram of a brake control apparatus according to an embodiment of the present invention;

FIG. 3 is one of the schematic diagrams of the preset front axle-rear axle brake force distribution constraints of the embodiment of the present invention;

FIG. 4 is a graphical illustration of a pedal mileage versus braking force demand relationship in accordance with an embodiment of the present invention;

FIG. 5 is a second schematic diagram illustrating predefined front axle-rear axle brake force distribution constraints in accordance with an embodiment of the present invention;

FIG. 6 is a third schematic diagram illustrating a predetermined front axle-rear axle brake force distribution constraint according to an embodiment of the present invention;

FIG. 7 is a fourth illustration of a preset front axle-rear axle brake force distribution constraint according to an embodiment of the present invention;

FIG. 8 is a fifth schematic view of a preset front axle-rear axle brake force distribution constraint in accordance with an embodiment of the present invention;

FIG. 9 is a sixth schematic view of a preset front axle-rear axle brake force distribution constraint in accordance with an embodiment of the present invention;

FIG. 10 is a seventh schematic illustration of a preset front axle-rear axle brake force distribution constraint according to an embodiment of the present invention;

FIG. 11 is an eighth schematic diagram illustrating a predetermined front-to-rear axle brake force distribution constraint in accordance with an embodiment of the present invention;

FIG. 12 is a ninth illustration of a default front axle-to-rear axle brake force distribution constraint, in accordance with an embodiment of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments. In the following description, specific details such as specific configurations and components are provided only to help the full understanding of the embodiments of the present invention. Thus, it will be apparent to those skilled in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

It should be appreciated that reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

In various embodiments of the present invention, it should be understood that the sequence numbers of the following processes do not mean the execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

It should be understood that the term "and/or" herein is merely one type of association relationship that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

In the embodiments provided herein, it should be understood that "B corresponding to a" means that B is associated with a from which B can be determined. It should also be understood that determining B from a does not mean determining B from a alone, but may be determined from a and/or other information.

Referring to fig. 1, an embodiment of the present invention provides a brake control method applied to a distributed drive automobile including an electric power assisted brake system, including:

step 101, acquiring required braking force, front axle electric brake recovery capacity and rear axle electric brake recovery capacity;

102, determining a current braking mode according to the required braking force, the front axle electric brake recovery capacity, the rear axle electric brake recovery capacity and preset front axle-rear axle braking force distribution constraint;

and 103, distributing the braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake according to the braking mode and the required braking force.

According to the embodiment of the invention, the current braking mode is determined by acquiring the required braking force, the front axle electric braking recovery capacity and the rear axle electric braking recovery capacity and combining the preset front axle-rear axle braking force distribution constraint, and the braking force is reasonably distributed to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake, so that the whole vehicle economy and the consistency of the deceleration process are realized.

The calculation of the braking force, the braking force distribution, and the like will be described below.

The hydraulic braking force of one side of the front wheel brake is as follows:

the hydraulic braking force of one side of the rear wheel brake is as follows:

the total hydraulic braking force is then:

the master cylinder pressure being equal to the front and rear wheel brake pressures, i.e. p_m＝p_f＝p_rAnd then:

N_t＝p_m×C＝p_f×C＝p_r×C (4)

defining constants

Wherein the content of the first and second substances,

D_f-front wheel cylinder diameter; d_r-rear wheel cylinder diameter; r_f-front brake radius; r_r-rear brake radius; k_bf-front brake coefficient of effectiveness; k_br-the rear brake coefficient of effectiveness; r is_wheel-the radius of the wheel; n is a radical of_f-front axle unilateral wheel hydraulic braking force; n is a radical of_r-rear axle unilateral wheel hydraulic braking force; n is a radical of_t-total hydraulic compaction power; p is a radical of_m-master cylinder hydraulic pressure; p is a radical of_f-front wheel hydraulic pressure; p is a radical of_r-rear wheel hydraulic pressure.

Referring to fig. 3, the constraint conditions of the braking force of the front and rear axles of the automobile are as follows: if the front axle is locked first, the automobile loses the steering capacity; if the rear axle is locked first, the automobile will sideslip. The ideal braking force distribution ensures that the front axle and the rear axle are not locked, if the wheels are locked, the front wheels can only be locked first, and the dangerous working condition that the rear wheels are locked first to cause the sideslip of the vehicle is avoided. The brake force distribution curve is located between the ideal brake force distribution I line and the ECE brake regulation limit line, and the stability of the braking process of the vehicle can be ensured, as shown in fig. 3.

Therefore, in the embodiment of the present invention, the principle of the braking force distribution is as follows: the front axle is distributed preferentially, when the motor capacity of the front axle can not meet the requirement, the front axle is transferred to the motor of the rear axle, and when the sum of the motor capacities of the front axle and the rear axle can not meet the requirement, the braking hydraulic pressure is needed for compensation. The priority of the braking mode in the following is set accordingly.

It will be appreciated that in an alternative embodiment of the present invention, the preset front axle-to-rear axle brake force distribution constraints are determined in accordance with the ideal brake force distribution I line and the ECE brake regulation limit line.

Referring to fig. 4, the step of acquiring the required braking force, the front axle electric brake recovery capability, and the rear axle electric brake recovery capability may include:

Assuming the recovery capability of the front left wheel motor as F_FL-limThe recovery capacity of the front right wheel motor is F_FR-limAnd the recovery capacity of the rear left wheel motor is F_RL-limAnd the recovery capacity of the rear right wheel motor is F_RR-limIn order to avoid the lateral deviation caused by the inconsistency of the braking force of the left wheel and the braking force of the right wheel, the recovery capacity of the two coaxial motors needs to be reduced, namely:

the brake recovery capacity of the front axle is:

F_F-lim＝2×min(F_FL-lim,F_FR-lim) (5)

the brake recovery capacity of the rear axle is:

F_R-lim＝2×min(F_RL-lim,F_RR-lim) (6)

wherein, the influence factors of the recovery capability of the single motor comprise: external characteristic limits of the motor, limits on motor system component temperatures, limits on motor system faults, limits on battery charging power, etc.

Referring to fig. 5, optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint includes:

Referring to fig. 5, the braking force at point a is the abscissa of the intersection of the ECE curve and the abscissa axis.

The situations that occur with pure electric braking and only front axle electric braking are: driver required braking force F_reqBraking force F less than or equal to A point_AAnd the driver demands the braking force F_reqIs less than or equal toFront axle brake recovery capability F_F-limAs shown in fig. 5, namely:

F_req≤F_F-limand F_req≤F_A(7)

Then: front left wheel brake recovery demand F_FL-reqBraking force F required for the driver_reqA times of the braking recovery requirement F of the front right wheel_FR-reqBraking force F required for the driver_reqWhere a + b is equal to 1 (it is understood that the following assignments for the front left and front right wheels of the front axle are also assigned to a times the left road, b times the right road, a + b is equal to 1, and preferably a is equal to 0.5, in the following examples, a is equal to 0.5 for simplicity of description), and the rear left wheel brake recovery request F is equal to 1_RL-reqRear right wheel brake recovery demand F_RR-reqAll are 0, master cylinder hydraulic demand P_regIs 0, namely the braking force required by the driver is completely provided by the braking recovery of the 2 motors on the front axle, the braking requirement of the 2 motors on the rear axle is 0, and the four wheel cylinders have no hydraulic pressure, namely:

referring to fig. 6, optionally, when the electric braking capability of the front axle is less than or equal to the first braking force, the step of determining the current braking mode according to the required braking force, the electric braking recovery capability of the front axle, the electric braking recovery capability of the rear axle, and the preset front axle-rear axle braking force distribution constraint includes:

Referring to fig. 6, in electric only braking and simultaneous front and rear axle braking, there is case 1:

the braking force at the point B is as follows: and drawing a straight line parallel to the ordinate axis by taking the braking recovery capacity of the front axle as an abscissa, and drawing an ordinate of the intersection point of the straight line and the I curve.

Case 1 of pure electric braking and simultaneous electric braking of the front and rear axles is: driver required braking force F_reqGreater than front axle brake recovery capacity F_F-limAnd the driver demands the braking force F_reqMinus front axle brake recovery capability F_F-limDifference of (D) is less than or equal to rear axle brake recovery capacity F_R-limAnd the driver demands the braking force F_reqMinus front axle brake recovery capability F_F-limDifference of less than or equal to B point braking force F_r-BAs shown in fig. 6, namely:

F_req-F_F-lim≤F_R-limand F_req-F_F-lim≤F_r-B(9)

Then: front left wheel brake recovery demand F_FL-reqFor front axle brake recovery capability F_F-lim0.5 times of the braking recovery requirement F of the front right wheel_FR-reqFor front axle brake recovery capability F_F-lim0.5 times of the brake recovery demand F of the rear left wheel_RL-reqBraking force F required for the driver_reqMinus front axle brake recovery capability F_F-lim0.5 times of difference, rear right wheel braking recovery demand F_RR-reqDriver required braking force F_reqMinus front axle brake recovery capability F_F-lim0.5 times of difference, master cylinder hydraulic demand P_reqIs 0, namely:

referring to fig. 7, optionally, when the electric braking capability of the front axle is greater than the first braking force, the step of determining the current braking mode according to the required braking force, the electric braking recovery capability of the front axle, the electric braking recovery capability of the rear axle, and the preset front axle-rear axle braking force distribution constraint includes:

Referring to fig. 7, in electric only braking and simultaneous front and rear axle braking, there is case 2:

The braking force at the point C is as follows: and drawing a straight line parallel to the ordinate axis with the brake recovery capability of the front axle as the abscissa, and the ordinate of the intersection point of the straight line and the ECE curve.

Case 2, where pure electric braking and simultaneous electric braking of the front and rear axles occur, is: driver required braking force F_reqGreater than front axle brake recovery capacity F_F-limAnd the driver demands the braking force F_reqMinus front axle brake recovery capability F_F-limDifference of (D) is less than or equal to rear axle brake recovery capacity F_R-limAnd the driver demands the braking force F_reqMinus front axle brake recovery capability F_F-limDifference of less than or equal to B point braking force F_r-BAnd the driver demands the braking force F_reqMinus front axle brake recovery capability F_F-limDifference of (D) is greater than or equal to point C braking force F_r-CAs shown in fig. 7, namely:

F_req-F_F-lim≤F_R-limand F_req-F_F-lim≤F_r-BAnd F_req-F_F-lim≥F_r-C(11)

referring to fig. 8, optionally, the electro-hydraulic braking mode includes: a first electro-hydraulic braking mode and a second electro-hydraulic braking mode of front axle electric braking, front axle hydraulic braking and rear axle hydraulic braking;

Referring to fig. 8, in front axle electric braking + front axle hydraulic braking + rear axle hydraulic braking in the electro-hydraulic braking, there is a case 1:

e point braking force: and according to the magnitude of the required braking force and the ECE curve, obtaining the point of the ECE curve meeting the magnitude of the required braking force as an E point.

D, braking force: and drawing a straight line through the point E, wherein the intersection point of the straight line and the beta line is a point D.

F_ECE-lim: the difference between the abscissa of point E and the abscissa of point D.

The situation 1 that electro-hydraulic simultaneous braking (front axle electric braking + front axle hydraulic braking + rear axle hydraulic braking) occurs is: the condition of pure electric braking is not satisfied, and the braking recovery capacity F of the front axle_F-limGreater than the difference F between the abscissa of the point E and the abscissa of the point D_ECE-limAs shown in fig. 8, namely:

F_F-lim≥F_ECE-lim(13)

then: front left wheel brake recovery demand F_FL-reqIs F_ECE-lim0.5 times of the braking recovery requirement F of the front right wheel_FR-reqIs F_ECE-lim0.5 times of the brake recovery demand F of the rear left wheel_RL-reqRear right wheel brake recovery demand F_RR-reqAll are 0, main cylinder hydraulic demand P_reqIs F_f-DCoefficient of passage C₁The conversion calculation results in:

wherein, constant C₁The conversion coefficient of the braking force of the front axle and the braking hydraulic pressure requirement of the master cylinder can be obtained according to the modes of experiments and the like, and is not described again.

Referring to fig. 9, optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint further includes:

Referring to fig. 9, in front axle electric braking + front axle hydraulic braking + rear axle hydraulic braking in electro-hydraulic braking, there is a case 2:

the situation 2 that electro-hydraulic simultaneous braking (front axle electric braking + front axle hydraulic braking + rear axle hydraulic braking) occurs is: the condition of pure electric braking is not satisfied, and the braking recovery capacity F of the front axle_F-limLess than the abscissa of point E and the abscissa of point DTarget difference F_ECE-limAs shown in fig. 9, namely:

F_F-lim＜F_ECE-lim(15)

then: front left wheel brake recovery demand F_FL-reqIs F_F-lim0.5 times of the braking recovery requirement F of the front right wheel_FR-reqIs F_F-lim0.5 times of the brake recovery demand F of the rear left wheel_RL-reqRear right wheel brake recovery demand F_RR-reqAll are 0, main cylinder hydraulic demand P_reqIs F_f-DCoefficient of passage C₁The conversion calculation results in:

Referring to fig. 10, optionally, the electro-hydraulic braking mode includes: a third electro-hydraulic braking mode and a fourth electro-hydraulic braking mode of front axle hydraulic braking, rear axle hydraulic braking and rear axle electric braking;

Referring to fig. 10, in front axle hydraulic braking + rear axle electric braking in electro-hydraulic braking, there is a case 1:

f point braking force: and according to the magnitude of the required braking force and the I curve, obtaining a point of the I curve meeting the magnitude of the required braking force as a point F.

D, braking force: and drawing a straight line through the point F, wherein the intersection point of the straight line and the beta line is a point D.

F_I-lim: the difference value of the vertical coordinate of the point F and the vertical coordinate of the point D.

The situation that electro-hydraulic simultaneous braking (front axle hydraulic braking + rear axle electric braking) occurs is that: front axle brake recovery capability F _F-lim0 and rear axle brake recovery capability F_I-limGreater than or equal to the difference F between the ordinate of the point F and the ordinate of the point D_I-limNamely:

F

_F-lim0 and F_R-lim≥F_I-lim(17)

Then: front left wheel brake recovery demand F_FL-reqFront right wheel brake recovery demand F _FR-req0, rear left wheel brake recovery demand F_RL-reqIs F_I-lim0.5 times of the braking recovery requirement F of the rear right wheel_RR-reqIs F_I-lim0.5 times of that of the master cylinder_reqIs F_f-DCoefficient of passage C₁The conversion calculation results in:

Referring to fig. 11, optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint further includes:

Referring to fig. 11, in front axle hydraulic braking + rear axle electric braking in electro-hydraulic braking, there is a case 2:

the situation that electro-hydraulic simultaneous braking (front axle hydraulic braking + rear axle electric braking) occurs is that: front axle brake recovery capability F _F-lim0 and rear axle brake recovery capability F_I-limLess than the difference F between the longitudinal coordinate of the point F and the longitudinal coordinate of the point D_I-limNamely:

F

_F-lim0 and F_R-lim＜F_I-lim(19)

wherein, constant C₁Is the conversion coefficient of the braking force of the front axle and the braking hydraulic demand of the master cylinder, and can be determined according to experiments and the likeThe mode is obtained, and is not described in detail herein.

Referring to fig. 12, optionally, the step of determining the current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and the preset front axle-rear axle braking force distribution constraint includes:

Pure liquid braking occurs in situations where: front axle brake recovery capability F _F-lim0, rear axle brake recovery capability F_R-limAt 0, the front and rear axle hydraulic pressure distribution is performed at this time according to line β, as shown in fig. 12, that is:

the constant C is a conversion coefficient between the braking force and the braking hydraulic pressure demand, and can be obtained through experiments and the like, and is not described herein again.

The embodiment of the invention ensures the economy of the vehicle: under the condition that the capacity of 4 motors on the front shaft and the rear shaft allows, the braking requirement of a driver is realized by motor braking; and under the condition that the motor capacity is not allowed or the constraint condition of the braking force distribution line is not satisfied, the hydraulic pressure is supplemented.

The embodiment of the invention also ensures the deceleration consistency of the vehicle: based on the decoupling scheme of the electric power-assisted brake system, when the motor capacity meets the requirement of a driver, brake fluid is sucked into the energy accumulator, the wheel cylinder has no hydraulic pressure, when the motor capacity does not meet the requirement of the driver or the brake force distribution constraint does not meet the requirement, the brake fluid is pushed out of the energy accumulator, and the wheel cylinder has the brake fluid pressure, so that the deceleration consistency of the vehicle is ensured.

The embodiment of the invention also ensures the safety of the vehicle: on one hand, the same braking force of the left wheel and the right wheel is ensured, and the lateral deviation caused by the difference of the left braking force and the right braking force is prevented, on the other hand, the braking force distribution is restrained based on the braking force distribution line, and the safety of the vehicle is ensured.

Referring to fig. 2, according to another aspect of the present invention, there is also provided a brake control apparatus for a distributed drive vehicle including an electric power assisted brake system, the apparatus including:

an obtaining module 201, configured to obtain a required braking force, a front axle electric brake recovery capability, and a rear axle electric brake recovery capability;

a determining module 202, configured to determine a current braking mode according to the required braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and a preset front axle-rear axle braking force distribution constraint;

and the control module 203 is used for distributing braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake according to the braking mode and the required braking force.

The device of the embodiment of the invention can realize each process in the method embodiment and has corresponding beneficial effects, and is not repeated here for avoiding repetition.

Optionally, the obtaining module includes:

the first acquisition unit is used for acquiring the travel of a brake pedal, the first recovery capacity of a front-axle left-wheel motor, the second recovery capacity of a front-axle right-wheel motor, the third recovery capacity of a rear-axle left-wheel motor and the fourth recovery capacity of a rear-axle right-wheel motor;

the second acquisition unit is used for acquiring the required braking force according to the travel of the brake pedal;

a third obtaining unit, configured to obtain the front axle electric brake recovery capacity according to the smaller of the first recovery capacity and the second recovery capacity;

and the fourth acquisition unit is used for acquiring the rear axle electric brake recovery capacity according to the smaller one of the third recovery capacity and the fourth recovery capacity.

Optionally, the determining module is specifically configured to:

Optionally, when the electric braking capability of the current shaft is less than or equal to the first braking force, the determining module is specifically configured to:

Optionally, when the electric braking capability of the current shaft is greater than the first braking force, the determining module is specifically configured to:

the determining module is further specifically configured to:

Optionally, the determining module is further specifically configured to:

the determining module is further specifically configured to:

Optionally, the determining module is further specifically configured to:

In summary, the embodiment of the invention determines the current braking mode by acquiring the required braking force, the front axle electric brake recovery capacity and the rear axle electric brake recovery capacity and combining the preset front axle-rear axle braking force distribution constraint, and reasonably distributes the braking force to the front axle motor, the rear axle motor, the front axle hydraulic brake and the rear axle hydraulic brake, thereby realizing the economy of the whole vehicle and the consistency of the deceleration process.

It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion.

Furthermore, the present invention may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A brake control method applied to a distributed drive automobile including an electric power assisted brake system, the method comprising:

2. The method of claim 1, wherein the braking mode comprises: a pure electric-front axle electric braking mode, a pure electric-front and rear axle electric braking mode, an electro-hydraulic braking mode and a pure liquid braking mode;

3. The method of claim 1, wherein the step of obtaining a requested braking force, a front axle electric brake recovery capability, and a rear axle electric brake recovery capability comprises:

4. The method of claim 2, wherein determining a current braking mode based on the requested braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and a preset front axle-to-rear axle braking force distribution constraint comprises:

5. The method of claim 2, wherein when a front axle electrical braking capability is less than or equal to a first braking force, the step of determining a current braking mode based on the requested braking force, the front axle electrical braking recovery capability, the rear axle electrical braking recovery capability, and a preset front axle-rear axle braking force distribution constraint comprises:

6. The method of claim 2, wherein when a front axle electrical braking capability is greater than a first braking force, determining a current braking mode based on the requested braking force, the front axle electrical braking recovery capability, the rear axle electrical braking recovery capability, and a preset front axle-rear axle braking force distribution constraint comprises:

7. The method of claim 2, wherein the electro-hydraulic braking mode comprises: a first electro-hydraulic braking mode and a second electro-hydraulic braking mode of front axle electric braking, front axle hydraulic braking and rear axle hydraulic braking;

8. The method of claim 7, wherein determining a current braking mode based on the requested braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and a preset front axle-to-rear axle braking force distribution constraint further comprises:

9. The method of claim 2, wherein the electro-hydraulic braking mode comprises: a third electro-hydraulic braking mode and a fourth electro-hydraulic braking mode of front axle hydraulic braking, rear axle hydraulic braking and rear axle electric braking;

10. The method of claim 9, wherein determining a current braking mode based on the requested braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and a preset front axle-to-rear axle braking force distribution constraint further comprises:

11. The method of claim 2, wherein determining a current braking mode based on the requested braking force, the front axle electric brake recovery capability, the rear axle electric brake recovery capability, and a preset front axle-to-rear axle braking force distribution constraint comprises:

12. A brake control apparatus for a distributed drive vehicle including an electric power assisted brake system, the apparatus comprising:

13. A controller comprising a processor, a memory and a computer program stored on the memory and executable on the processor, the computer program, when executed by the processor, implementing the steps of the brake control method according to any one of claims 1 to 11.

14. A computer-readable storage medium, characterized in that a computer program is stored on the computer-readable storage medium, which computer program, when being executed by a processor, carries out the steps of the brake control method according to any one of claims 1 to 11.