CN113460012A

CN113460012A - Vehicle braking method and device, vehicle control method and vehicle

Info

Publication number: CN113460012A
Application number: CN202010245016.4A
Authority: CN
Inventors: 陆国祥; 刘少华; 朱新明; 何邵陵; 孔银龙
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2020-03-31
Filing date: 2020-03-31
Publication date: 2021-10-01
Anticipated expiration: 2040-03-31
Also published as: CN113460012B

Abstract

The embodiment of the invention discloses a vehicle braking method and device, a vehicle control device, a vehicle and a computer readable storage medium. The method comprises the following steps: determining whether the battery capacity of the vehicle is lower than a preset value during the running of the vehicle; under the condition that the battery electric quantity is lower than the preset value, acquiring the current effective braking travel of a brake pedal of the vehicle, wherein the total effective braking travel of the brake pedal is segmented into a plurality of sections, and each section corresponds to a different braking mode; determining the interval of the current effective braking travel; and braking the vehicle according to the braking mode corresponding to the interval where the current effective braking travel is located.

Description

Vehicle braking method and device, vehicle control method and vehicle

Technical Field

The present invention relates to the field of vehicle braking, and in particular, to a vehicle braking method and apparatus, a vehicle control method, a vehicle, and a computer-readable storage medium.

Background

The existing automobile braking method comprises traditional hydraulic braking and electro-hydraulic coupling braking including motor braking, and the final control target is controlled by the deceleration corresponding to the depth of the pedal. The depth of the brake pedal corresponds to the deceleration, and by stepping on the pedal at different depths, different decelerations are obtained. The greater the deceleration, the faster the brake is stopped.

The method comprises the steps of calculating the required braking deceleration in real time through electro-hydraulic coupling braking, converting the braking deceleration into the braking torque requirement, presetting the motor braking torque in a braking system controller in a MAP table look-up mode, and generally dividing the braking torque into a plurality of braking strength grades, such as a built-in user-adjustable strong grade, a built-in user-adjustable medium grade and a built-in user-adjustable weak grade. This solution requires more hydraulic braking intervention since the motor braking torque is fixed. The hydraulic brake is a mechanical brake, and the friction-generated hydraulic brake causes more kinetic energy to be converted into heat energy, and the kinetic energy is not fully converted into electric energy and stored. Therefore, it is disadvantageous in energy recovery and is slightly less economical.

Disclosure of Invention

An object of an embodiment of the present invention is to provide a vehicle braking method and apparatus, a vehicle control method, a vehicle, and a computer-readable storage medium to sufficiently recover battery power.

According to a first aspect of the present invention, there is provided a vehicle braking method comprising:

determining whether the battery capacity of the vehicle is lower than a preset value during the running of the vehicle;

under the condition that the battery electric quantity is lower than the preset value, acquiring the current effective braking travel of a brake pedal of the vehicle, wherein the total effective braking travel of the brake pedal is segmented into a plurality of sections, and each section corresponds to a different braking mode;

determining the interval of the current effective braking travel;

and braking the vehicle according to the braking mode corresponding to the interval where the current effective braking travel is located.

Optionally, the total effective braking stroke of the brake pedal is segmented into a first interval and a second interval, the first interval is located between 0 and L1, the second interval is located between L2 and L3, 0< L1< L2< L3, the braking mode corresponding to the first interval is first motor braking, and the braking mode corresponding to the second interval is motor/hydraulic combined braking.

Optionally, when the current effective braking stroke is located in the first interval, braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located includes:

acquiring the current speed of the vehicle and the initial speed of the brake pedal when the brake pedal initially enters an effective brake stroke;

determining a target vehicle speed according to the initial vehicle speed, the current effective brake stroke and an upper limit value of the effective brake stroke corresponding to the first interval;

and determining the motor braking demand torque of the vehicle according to the target vehicle speed and the current vehicle speed, and performing first motor braking on the vehicle.

Optionally, the target vehicle speed is determined according to the following equation:

and V2 is the target vehicle speed, V1 is the initial vehicle speed, L is the current effective brake stroke value, and L1 is the upper limit value of the effective brake stroke corresponding to the first interval.

Optionally, the braking demand torque of the motor is determined according to the following equation:

wherein T is the braking demand torque of the motor, K_pAnd K_iRespectively, are preset demand PI parameters, and V is the current vehicle speed.

Optionally, when the current effective braking stroke is located in the second interval, braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located includes:

obtaining the maximum braking torque of a motor of the vehicle and continuously performing motor braking on the vehicle by using the maximum braking torque of the motor;

determining the total required braking torque of the vehicle according to the preset deceleration and the current effective braking travel;

determining the hydraulic braking demand torque of the vehicle according to the total demand braking torque and the maximum braking torque of the motor, and performing hydraulic braking on the vehicle;

and combining the maximum braking torque of the motor and the hydraulic braking demand torque to perform motor/hydraulic combined braking on the vehicle.

Optionally, the total effective braking stroke further includes a third interval, the third interval is located between L1 and L2, and a braking manner corresponding to the third interval is braking by the second motor.

Optionally, when the current effective braking stroke is located in the third interval, braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located includes:

acquiring the current motor rotating speed and the motor peak power of the vehicle;

determining the motor braking demand torque of the vehicle according to the current motor rotating speed and the motor peak power, and performing second motor braking on the vehicle;

wherein the method further comprises:

and establishing high pressure of a hydraulic braking system and pre-charging the high pressure while performing second motor braking on the vehicle according to the motor braking demand torque so as to introduce hydraulic braking to the vehicle in the second interval.

Optionally, the interval value corresponding to the third interval is smaller than the interval value corresponding to the first interval, and/or the interval value corresponding to the third interval is smaller than the interval value corresponding to the second interval.

Optionally, before acquiring the current effective braking stroke of the brake pedal of the vehicle, the method further includes:

determining whether the current braking stroke of the brake pedal is an effective braking stroke or an ineffective braking stroke;

and under the condition that the current braking stroke of the brake pedal is determined to be an effective braking stroke, determining the current braking stroke as the current effective braking stroke.

Optionally, in a case that the current braking stroke of the brake pedal is determined to be an ineffective braking stroke, the method further includes:

and under the condition that the accelerator pedal of the vehicle is released, determining the motor braking demand torque of the vehicle according to the current speed and the current braking intensity level of the vehicle, and performing motor braking on the vehicle.

Optionally, in a case that the battery power is not lower than the predetermined value, the method further includes:

braking the vehicle using hydraulic braking.

Optionally, the vehicle is braked according to a braking mode corresponding to an interval where the current effective braking travel is located, and the vehicle is braked according to a braking mode at least including motor braking, so that the current speed of the vehicle is reduced to a preset threshold value.

Optionally, in a case that the current vehicle speed of the vehicle drops to a predetermined threshold, the method further includes:

and canceling the motor brake, and braking the vehicle by using hydraulic brake.

Optionally, the vehicle is braked according to a braking mode corresponding to an interval where the current effective braking stroke is located, and the vehicle is braked according to motor braking and hydraulic braking so as to trigger a braking anti-lock system or an electronic stability control system of the vehicle.

Optionally, in the case of triggering a brake anti-lock system or an electronic stability control system of the vehicle, the method further comprises:

and preferentially adjusting the braking torque of the motor brake according to the braking demand of the vehicle.

According to a second aspect of the present invention, there is provided a vehicle brake device including:

the device comprises a first determination module, a second determination module and a control module, wherein the first determination module is used for determining whether the battery capacity of a vehicle is lower than a preset value during the running process of the vehicle;

the obtaining module is used for obtaining the current effective braking travel of a brake pedal of the vehicle under the condition that the electric quantity of the battery is lower than the preset value, wherein the total effective braking travel of the brake pedal is segmented into a plurality of sections, and each section corresponds to a different braking mode;

the second determining module is used for determining the interval of the current effective braking travel;

and the braking module is used for braking the vehicle according to a braking mode corresponding to the interval where the current effective braking stroke is located.

Optionally, the braking module is configured to brake the vehicle according to a corresponding braking manner when the current effective braking stroke is in a first interval, and includes:

and determining the motor braking demand torque of the vehicle according to the target vehicle speed and the current vehicle speed, and performing motor braking on the vehicle.

Optionally, the braking module is configured to brake the vehicle according to a corresponding braking manner when the current effective braking stroke is in a second interval, and includes:

wherein motor/hydraulic hybrid braking is performed on the vehicle in combination with the motor maximum braking torque and the hydraulic braking demand torque.

Optionally, the braking module is configured to brake the vehicle according to a corresponding braking manner when the current effective braking stroke is in a third interval, and includes:

determining the motor braking demand torque of the vehicle according to the current motor rotating speed and the motor peak power, and performing motor braking on the vehicle;

wherein the apparatus further comprises:

and the establishing module is used for establishing high pressure of a hydraulic braking system and performing high-pressure pre-charging while performing motor braking on the vehicle according to the motor braking required torque so as to introduce hydraulic braking to the vehicle in the second interval.

According to a third aspect of the present invention, there is provided a vehicle brake device including: a memory and a processor; the memory stores instructions which, when executed by the processor, implement the method according to the first aspect of the invention.

According to a fourth aspect of the present invention, there is provided a vehicle control apparatus comprising: a memory and a processor; the memory stores instructions which, when executed by the processor, implement the method according to the first aspect of the invention.

According to a fifth aspect of the invention, there is provided a vehicle including the vehicle brake device according to the second or third aspect of the invention or the vehicle control device according to the fourth aspect of the invention.

According to a sixth aspect of the present invention, there is provided a computer readable storage medium having stored thereon a computer program which, when executed by a processor, performs the method according to the first aspect of the present invention.

According to the embodiment of the invention, when the electric quantity of the battery is lower than the preset value, the motor can be adopted for braking, the effective braking stroke of the brake pedal is divided into a plurality of sections, and different braking modes are adopted corresponding to different sections, so that the energy can be fully recovered, and the vehicle economy is improved. Meanwhile, the advantages of quick response and better braking smoothness of motor braking can be fully embodied.

Other features of the present invention and advantages thereof will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Fig. 1 is a schematic structural diagram of a vehicle brake system that can be used to implement an embodiment of the present invention.

FIG. 2 is a flowchart of the steps of a vehicle braking method according to an embodiment of the present invention.

FIG. 3 is a flowchart illustrating exemplary steps of a method for braking a vehicle according to an embodiment of the present invention.

Fig. 4 is a block diagram showing the construction of a vehicle brake device according to an embodiment of the present invention.

Fig. 5 is a block diagram showing the structure of a vehicle according to the first embodiment of the invention.

Fig. 6 is a block diagram showing the structure of a vehicle according to a second embodiment of the invention.

Detailed Description

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

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

The electro-hydraulic coupling brake of the existing vehicle obtains the motor brake torque to output the motor brake power according to the required deceleration, but the motor brake torque is obtained according to a fixed chart, in order to meet the deceleration, when the motor power reaches the maximum torque due to high rotating speed, the motor brake power output is insufficient, more hydraulic brakes are needed to be used for converting kinetic energy into friction force for braking, and therefore the generation and recovery of electric energy are reduced. The vehicle braking scheme provided by the embodiment of the invention can realize more electric energy recovery.

Fig. 1 is a schematic structural diagram showing a vehicle brake system in which an embodiment of the invention can be implemented.

As shown in fig. 1, the vehicle braking system of this embodiment may include components, modules or systems such as a brake pedal depth sensor 1200, an accelerator pedal depth sensor 1400, a hydraulic braking system 1800, a motor controller 1600, a battery level estimation module 1100, a vehicle speed detection system 1900 (or a vehicle speed estimation module), a braking system controller 1000 (e.g., which may be integrated into a core electronic control unit (VCU) of a vehicle control system).

The battery charge estimation module 1200 is used for estimating or monitoring a battery charge, i.e., a State of charge (SOC), of the vehicle. The vehicle speed detection system 1900 is configured to detect a real-time vehicle speed of a vehicle, the brake pedal depth sensor 1200 is configured to detect a brake pedal depth travel signal generated corresponding to a pedal depth when a brake pedal is stepped on, and the accelerator pedal depth sensor 1400 is configured to detect an accelerator pedal depth travel signal generated corresponding to a pedal depth when an accelerator pedal is stepped on. The braking system controller 1000 receives signals sent by the brake pedal depth sensor 1200, the accelerator pedal depth sensor 1400, the battery power estimation module 1200 and the vehicle speed detection system 1900, and controls the motor controller 1600 and the hydraulic braking system 1800 to correspondingly execute motor braking and hydraulic braking respectively.

< method examples >

Referring to fig. 2, in one embodiment of the present invention, a vehicle braking method is provided, and fig. 2 is a flowchart illustrating steps of the vehicle braking method according to the embodiment of the present invention.

As shown in fig. 2, the vehicle braking method includes the steps of:

step 102, during the vehicle journey, determining whether the battery charge of the vehicle is lower than a predetermined value.

And 104, acquiring the current effective braking travel of a brake pedal of the vehicle under the condition that the electric quantity of the battery is lower than a preset value, wherein the total effective braking travel of the brake pedal is segmented into a plurality of intervals, and each interval corresponds to a different braking mode.

And step 106, determining the section of the current effective travel.

And 108, braking the vehicle according to the braking mode corresponding to the interval of the current effective travel.

In the process of vehicle travel, the battery electric quantity estimation module monitors the SOC in real time, and when the SOC is lower than a certain preset value, the current effective braking travel of the brake pedal is obtained in the electric quantity state. As an example, the predetermined value may be, for example, 80% to 90% of the total charge of the battery.

The brake pedal comprises an effective brake stroke and an ineffective brake stroke, the effective brake stroke is a stroke when the vehicle starts to brake, namely a signal of the brake pedal depth sensor is not zero, the vehicle brakes, and the following braking is a braking action of detecting a signal of the effective brake stroke (namely a signal sent by the brake pedal sensor is not zero). The invalid braking stroke, namely the idle stroke part is the motion space part of the actual pedal, and in the idle stroke part, the signal of the depth sensor of the brake pedal is zero, and the vehicle is not braked.

In one embodiment, in the effective braking stroke of the brake pedal, the total effective braking stroke (unit: mm) of the brake pedal can be segmented into a first interval (0-L1) and a second interval (L2-L3) according to a preset range, wherein 0-L1 (without 0) is a vehicle speed control part, and the corresponding braking mode is a first motor brake, which means a motor brake, but different motor braking modes can be adopted or different motor braking modes can be obtained for the motor torque. L2-L3 are electro-hydraulic compound brake parts, and the corresponding brake mode is motor/hydraulic compound brake. Wherein 0< L1< L2< L3.

In one embodiment, the total effective braking stroke of the brake pedal can be segmented into a first interval (0-L1), a third interval (L1-L2) and a second interval (L2-L3), wherein L1-L2 are stable transition portions, and the corresponding braking mode is second motor braking. Here, the second motor brake is also a motor brake mode, and the second motor brake may be the same as or different from the first motor brake.

Since the lengths of the brake pedals of different vehicle types are different, as an example, the brake stroke interval value corresponding to the first interval may occupy, for example, about 30% to 40% of the total stroke of the brake pedal, the brake stroke interval value corresponding to the second interval may occupy, for example, about 30% to 40% of the total stroke of the brake pedal, the brake stroke interval value corresponding to the third interval may occupy, for example, about 5% to 10% of the total stroke of the brake pedal, and the idle stroke portion occupies about 5% to 10%. The total stroke of the brake pedal comprises two parts of an idle stroke and a total effective braking stroke.

Next, the braking manner corresponding to the above-described different sections will be explained.

(1) The brake is positioned in the interval of 0-L1

When the current effective braking stroke L corresponding to the brake pedal depth signal sent by the brake pedal depth sensor is in the interval of 0-L1, the brake controller calculates the target vehicle speed V2.

In one embodiment, when calculating the target vehicle speed V2, an initial vehicle speed V1 is first obtained at which the brake pedal initially enters an active braking stroke. When the initial vehicle speed V1 is the time when the first data that the brake pedal depth signal is not zero is detected when the brake pedal is depressed, the vehicle speed at that time is recorded as the initial vehicle speed. And determining the target vehicle speed V2 according to the initial vehicle speed V1, the current effective brake stroke L and the upper limit value (namely L1) of the effective brake stroke corresponding to the first interval.

In one embodiment, the target vehicle speed V2 is determined, for example, according to the following equation:

as described above, the braking mode corresponding to the interval 0 to L1 is the first motor braking, and the vehicle is braked by using only the motor braking mode.

In one embodiment, the first motor braking is to perform motor braking on the vehicle by performing motor braking demand torque calculation through a one-way PI (proportional integral) regulation manner and determining the motor braking demand torque of the vehicle according to the target vehicle speed V2 and the current vehicle speed V of the vehicle.

Specifically, the motor braking demand torque T is calculated according to the following equation:

in the formula, K_pAnd K_iAnd respectively, PI parameters needing to be calibrated, and V is the vehicle speed at the current moment.

The first motor brake of the one-way PI regulation is that when the calculated motor brake demand torque is a negative value, namely the actual current vehicle speed V is greater than the target vehicle speed V2, the motor does not output torque, the vehicle is kept in a sliding state, the situation occurs that the brake pedal is maintained for a period of time, the brake pedal is lifted again after the vehicle speed is reduced to a certain value, and the established target vehicle speed is higher than the current vehicle speed. In this case, the motor does not provide braking torque.

In one embodiment, the target vehicle speed V2 is varied in real time following the brake pedal depth L, but the target vehicle speed V2 exists only within a preset range of brake pedal depths within the vehicle speed control interval (first interval 0-L1), which is no longer cleared. The depth L of the depth pedal is not within a preset range of 0-L1, and four possibilities are available, wherein one possibility is to lift the brake pedal, the other three possibilities are respectively located in an idle stroke interval, a stable transition interval (a third interval) and an electro-hydraulic compound brake interval (a second interval), when the vehicle speed control interval (a first interval) enters from the stable transition interval (the third interval) or enters from the idle stroke interval (the first interval), the initial vehicle speed V1 is recorded according to the first moment when the brake pedal initially enters the vehicle speed control interval (the first interval), then the brake system controller calculates the target vehicle speed V2 according to the real-time position (namely the current effective brake stroke) of the brake pedal and the initial vehicle speed V1, and the calculated real-time target vehicle speed V2 is used as the target of PI control of the first motor brake.

In this way, when the first motor brake is applied, a torque in the opposite direction to the torque used for forward travel of the vehicle is generated, whereby a braking force is generated to reduce the vehicle speed and reduce the kinetic energy. When the motor provides reverse torque, motor feedback current generated by cutting the magnetic induction lines by the electromagnetic coil can be transmitted back to the battery, and current energy recovery is realized.

(2) The brake is positioned between the interval L1 and L2

When the current effective braking stroke L corresponding to the brake pedal depth signal sent by the brake pedal depth sensor is in the interval L1-L2, the corresponding braking mode is the second motor braking mode, the vehicle is braked by using the motor braking mode, and hydraulic braking can be introduced in the subsequent interval L2-L3.

In one embodiment, the second motor braking is to determine a motor braking demand torque of the vehicle according to the current motor speed and the peak motor power of the vehicle, and the vehicle is subjected to motor braking.

For example, the motor braking demand torque may be calculated by the following equation:

wherein T is the braking demand torque of the motor (unit: Newton meter), P is the peak power of the motor (unit: kilowatt), and n is the current rotating speed of the motor (unit: revolution/minute). k is a constant, e.g., 9550.

The motor speed is obtained by a motor speed sensor, and the peak power of the motor is usually a fixed value. Under the condition that the motor of the vehicle can not reach the peak power of the motor according to the current state of the motor, the electric control and/or the battery of the vehicle, the motor braking required torque of the vehicle is determined according to the current motor rotating speed and the maximum power which can be provided by the motor.

The motor braking demand torque corresponding to the second motor braking is related to the motor torque and the vehicle speed in the range of the interval L1-L2 and is not related to the depth of a brake pedal, namely the effective braking stroke.

In one embodiment, the high pressure of the hydraulic brake system is initially established and high pressure pre-charged while the electric machine braking demand torque is obtained. The high pressure required by the hydraulic brake system requires a certain time to build up, i.e. the liquid cannot reach the required pressure at once. Therefore, when high pressure is required to be introduced in the subsequent L2-L3 interval, the required pressure can be established from 0 in the transition interval of the L1-L2 interval, and high-pressure pre-charging is carried out in a gradual transition mode, so that the required high-pressure can be quickly and smoothly reached in the subsequent L2-L3 interval. Thus, the hydraulic brake response time when hydraulic braking is required to be involved can be shortened. Because the interval L1-L2 is a stable transition stage, the effective braking stroke of the pedal in the interval is obviously smaller than the stroke of the vehicle speed control interval and the stroke of the electro-hydraulic (motor/hydraulic) composite braking interval optionally. That is, the interval value corresponding to the difference between L2 and L1 is smaller than the interval value corresponding to L1, and smaller than the interval value corresponding to the difference between L3 and L2.

Therefore, when the second motor is braked, the motor generates feedback current to realize current energy recovery.

(3) The brake is positioned between the interval L2 and L3

When the current effective brake stroke L corresponding to the brake pedal depth signal sent by the brake pedal depth sensor is in the interval L2-L3, the maximum brake torque which can be provided by the motor is obtained, and the maximum brake force corresponding to the maximum brake torque is continuously kept for carrying out motor braking. And (3) gradually increasing the braking force of the hydraulic system along with the increase of the depth of the brake pedal, and in the electro-hydraulic composite braking interval, calculating the total required braking torque according to the preset deceleration and the current effective braking stroke corresponding to the depth of the brake pedal, namely the braking torque which is required to be provided by the motor brake and the hydraulic brake together. And then subtracting the maximum braking torque of the motor which can be provided by the actual motor from the total required braking torque to obtain the required torque of the hydraulic brake.

When the electro-hydraulic composite braking is carried out in the interval, the recovery of current energy can be realized by utilizing the motor braking.

In one embodiment, in a case where the SOC is lower than the predetermined value, before acquiring a current effective braking stroke of a brake pedal of the vehicle, the vehicle braking method of the embodiment of the invention further includes: determining whether the current braking stroke of the brake pedal is an effective braking stroke or an ineffective braking stroke; and under the condition that the current braking stroke of the brake pedal is determined to be the effective braking stroke, taking the current braking stroke as the current effective braking stroke.

As described above, the ineffective braking stroke is the idle stroke of the brake pedal. In one example, the stroke interval value corresponding to the idle stroke may be, for example, about 5% to 10% of the total stroke of the brake pedal.

According to one embodiment of the invention, in the case that the current braking stroke of the brake pedal is determined to be the ineffective braking stroke, if the vehicle has the condition that the accelerator pedal is released, the motor braking demand torque of the vehicle is determined according to the current vehicle speed and the current braking intensity level of the vehicle so as to perform motor braking on the vehicle.

And according to the current vehicle speed and the brake intensity grade, performing table lookup on a built-in MAP (MAP) MAP to obtain the motor brake required torque. Also, when motor braking is performed, torque in the opposite direction to the torque used for forward travel of the vehicle is generated, whereby braking force is generated so that the vehicle speed is reduced and kinetic energy is reduced. When the motor provides reverse torque, feedback current generated by cutting the magnetic induction lines by the electromagnetic coil of the motor is controlled by the motor controller to be transmitted back to the battery, so that current energy recovery is realized.

In one embodiment, when the SOC is not lower than the predetermined value, the motor does not participate in braking when the accelerator pedal is closed and the brake pedal is stepped on, and in this electric quantity state, the accelerator pedal is released, the vehicle slides, and the motor does not feed back current. When the brake pedal is depressed, braking is performed by hydraulic pressure, and the braking deceleration and the brake pedal depth (i.e., the effective braking stroke) are positively correlated throughout the effective brake pedal stroke.

In the vehicle braking with the motor participating, the motor braking demand torque and the motor actually-sent torque may be different, the actual motor-sent torque is limited by the motor working environment (motor and electric control temperature), the motor peak power, the battery maximum charging power and other factors, and the motor braking demand torque is obtained by correspondingly adopting PI control calculation or MAP table look-up or calculation according to the vehicle speed and the motor peak power according to different effective braking stroke intervals in a segmentation manner, so that the target motor braking torque sent by the motor controller is the actual executable braking torque limited by the factors.

In the speed control interval, if the speed of a motor vehicle is higher, same footboard degree of depth remains unchanged, receive the influence of motor power in the earlier stage, motor braking torque is less, when the speed of a motor vehicle descends gradually and does not descend to the target speed of a motor vehicle, integral error is increasing all the time, through reasonable PI setting, make demand motor braking torque also increase, the motor can provide braking torque and also increase again, braking torque can crescent, this is the advantage of the speed control who adopts first motor braking also, can provide better ride comfort, also can make full use of motor ability.

If the motor braking force does not meet the deceleration requirement in a short time, the stepping stroke of the brake pedal can be increased in the electro-hydraulic composite braking interval, and the safety of the vehicle is kept by enabling hydraulic braking to participate.

According to the embodiment of the invention, the stable transition interval is further included, the braking mode of vehicle speed control is changed into the braking mode of electro-hydraulic hybrid control, and the buffering effect is achieved, so that human body discomfort and driving risks caused by direct back-and-forth switching of the two braking modes are reduced.

In one embodiment, when the vehicle is braked according to the braking mode corresponding to the section where the current effective braking travel is located, the vehicle is braked according to the mode including motor braking, and the current speed of the vehicle is reduced to a preset threshold value, the motor braking is cancelled, and the vehicle is braked by using hydraulic braking.

Specifically, when a brake pedal is stepped on and motor braking participates (such as a vehicle speed control interval, a stable transition interval and an electro-hydraulic combined braking interval), if the vehicle speed is reduced to a certain threshold value (such as about 1 to 3 km/h), the motor braking torque is cancelled and pure hydraulic braking is added in the vehicle speed control interval and the stable transition interval, and the pure hydraulic braking torque is preset by a braking control system according to the vehicle weight and the ramp information. In the electro-hydraulic compound braking interval, the motor braking torque is cancelled, and hydraulic braking is reserved, so that the possibility that the vehicle slips backwards after the vehicle stops due to the fact that reverse motor braking torque is continuously applied is prevented, and the safety of vehicle braking is improved.

In one embodiment, when braking the vehicle according to the braking mode corresponding to the section where the current effective braking stroke is located is to trigger an anti-lock brake system (ABS) or an electronic stability control system of the vehicle when braking the vehicle according to the motor braking and the hydraulic braking, the braking torque of the motor braking is preferentially adjusted according to the braking requirement of the vehicle.

Specifically, when the braking with the motor involved triggers the ABS, the adjustment of the motor braking torque, such as increasing or decreasing the motor braking torque, is performed preferentially because the motor torque control response is generally faster than the hydraulic response, and if the motor braking torque is completely unloaded and the braking torque is still larger, the adjustment of the hydraulic braking is performed again. When the braking with the motor is triggered by an Electronic stability control system (ESP), an Electronic stability control system (ESC), or the like, the motor braking torque is adjusted or cancelled according to the requirements of the ESP. Therefore, the brake of the vehicle can be responded more quickly and efficiently, and the reduction of comfort caused by the brake of the vehicle is reduced.

According to the vehicle braking method, the braking strategy is automatically adjusted according to the electric quantity of the battery, when the electric quantity is sufficient, the motor braking torque is cancelled, and when the electric quantity is lower than the limit value, the motor braking torque is added during braking. In the braking control with the participation of the motor, a brake pedal depth interval is divided into a plurality of interval parts, such as a vehicle speed control part and an electro-hydraulic compound braking part. In one embodiment, the method can be further divided into four parts: the system comprises an idle stroke part, a vehicle speed control part, a stable transition part and an electro-hydraulic composite braking part. Different motor braking modes are adopted corresponding to different interval parts, so that energy can be fully recovered, and the vehicle economy is improved. Meanwhile, the brake system has the advantages of quick response of motor braking and good braking smoothness.

In addition, the vehicle speed control part is added, so that the driver can run at a reduced speed more conveniently and comfortably. The addition of the stable transition portion also further improves the smoothness of the vehicle when braking and the driving comfort of the driver.

< example >

Now, a vehicle braking method according to an embodiment of the present invention will be described by way of example with reference to fig. 3.

As shown in fig. 3, the method comprises the following steps:

step 202, determining whether the battery power SOC is lower than a predetermined threshold, if so, entering step 204, otherwise, entering step 216.

In step 204, it is determined whether the braking signal corresponding to the effective braking stroke of the brake pedal is not 0, if yes, step 206 is performed, otherwise step 218 is performed.

In step 206, it is determined whether the interval corresponding to the current effective braking stroke is 0-L1, if so, go to step 208, otherwise, go to step 210.

And step 208, using the motor brake to brake the vehicle by controlling the vehicle speed through the PI.

In step 210, it is determined whether the interval corresponding to the current effective braking stroke is an interval from L1 to L2, if so, the process goes to step 212, otherwise, the process goes to step 214.

And step 212, outputting the maximum motor torque to brake the vehicle.

And step 214, performing vehicle braking by using the electro-hydraulic compound braking.

Step 216, when the SOC is lower than a preset threshold value, the motor brake is not used, and the accelerator is collected without refund brake; when the brake pedal is stepped on, hydraulic brake is used, and the brake depth and the deceleration are positively correlated.

In step 218, it is determined whether the vehicle is in a throttle released state, if so, step 220 is entered, otherwise, step 222 is entered.

And step 220, obtaining the motor braking force through a MAP table look-up by using the motor brake.

In step 222, if the braking signal is 0 and there is no accelerator release, there is no braking action.

< first embodiment of the apparatus >

In another embodiment of the present invention, there is also provided a vehicle brake apparatus 2000, as shown in fig. 4, the vehicle brake apparatus 2000 including: the system includes a first determination module 2200, an acquisition module 2400, a second determination module 2600, and a brake module 2800.

The first determining module 2200 is configured to determine whether a battery charge of the vehicle is lower than a predetermined value during the running of the vehicle, and the obtaining module 2400 is configured to obtain a current effective braking stroke of a brake pedal of the vehicle if the battery charge is lower than the predetermined value, where a total effective braking stroke of the brake pedal is segmented into a plurality of sections, and each section corresponds to a different braking manner. The second determination module 2600 is configured to determine an interval in which the current active brake stroke is located. The braking module 2800 is configured to brake the vehicle according to a braking manner corresponding to an interval where the current effective braking stroke is located.

In one embodiment, the total effective braking stroke comprises a first interval and a second interval, wherein the first interval is between 0 and L1 (without 0), the second interval is between L2 and L3, 0< L1< L2< L3, the first interval corresponds to a first motor braking mode, and the second interval corresponds to a motor/hydraulic combined braking mode.

In one embodiment, the braking module 2800 is configured to brake the vehicle according to a corresponding braking mode when the current available braking distance is in the first interval, and includes: acquiring the current speed of the vehicle and the initial speed of the brake pedal when the brake pedal initially enters an effective brake stroke; determining a target vehicle speed according to the initial vehicle speed, the current effective brake stroke and the upper limit value of the effective brake stroke corresponding to the first interval; and determining the motor braking demand torque of the vehicle according to the target vehicle speed and the current vehicle speed so as to perform motor braking on the vehicle.

In one embodiment, the target vehicle speed is determined according to the following equation:

wherein, V2 is the target vehicle speed, V1 is the initial vehicle speed, L is the current effective brake stroke value, and L1 is the upper limit value of the effective brake stroke corresponding to the first interval.

In one embodiment, the motor braking demand torque is determined according to the following equation:

In one embodiment, the braking module is configured to brake the vehicle according to a corresponding braking manner when the current effective braking stroke is in the second interval, and includes: obtaining the maximum braking torque of a motor of the vehicle and continuously braking the motor of the vehicle by using the maximum braking torque of the motor; determining the total required braking torque of the vehicle according to the preset deceleration and the current effective braking travel; determining the hydraulic braking demand torque of the vehicle according to the total demand braking torque and the maximum braking torque of the motor, and performing hydraulic braking on the vehicle; the vehicle is subjected to motor/hydraulic combined braking by combining the maximum braking torque of the motor and the hydraulic braking demand torque.

In one embodiment, the total effective braking stroke further comprises a third interval, the third interval is located between L1 and L2, and the braking mode of the third interval is the braking mode of the second motor.

In one embodiment, the braking module 2800 is configured to brake the vehicle according to a corresponding braking manner if the current available braking distance is in the third interval, and includes: acquiring the current motor rotating speed and the motor peak power of a vehicle; determining the motor braking demand torque of the vehicle according to the current motor rotating speed and the motor peak power, performing motor braking on the vehicle,

the vehicle braking device 2000 further includes a building module (not shown in the figure) for building high pressure of the hydraulic braking system and pre-charging the high pressure while performing motor braking on the vehicle according to the motor braking demand torque, so as to introduce hydraulic braking to the vehicle in the second interval.

In one embodiment, the interval value corresponding to the third interval is smaller than the interval value corresponding to the first interval, and/or the interval value corresponding to the third interval is smaller than the interval value corresponding to the second interval.

In one embodiment, the vehicle brake apparatus 2000 further includes:

a third determining module (not shown in the figure) for determining whether the current braking stroke of the brake pedal is an effective braking stroke or an ineffective braking stroke before the current effective braking stroke of the brake pedal of the vehicle is obtained; and under the condition that the current braking stroke of the brake pedal is determined to be the effective braking stroke, taking the current braking stroke as the current effective braking stroke.

In one embodiment, the vehicle brake apparatus 2000 further includes:

and a fourth determining module (not shown in the figure) for determining the motor braking demand torque of the vehicle according to the current vehicle speed and the current braking intensity level of the vehicle to perform motor braking on the vehicle under the condition that the current braking stroke of the brake pedal is determined to be an invalid braking stroke and the vehicle releases the accelerator pedal.

In one embodiment, in the event that the battery level is not below the predetermined value, the braking module 2800 is further configured to: the vehicle is braked using hydraulic braking.

In one embodiment, the vehicle is braked according to a braking mode corresponding to an interval where a current effective braking travel is located, and the vehicle is braked according to a braking mode at least comprising motor braking, so that the current speed of the vehicle is reduced to a preset threshold value.

In one embodiment, the braking module 2800 is also used to: and in the case that the current vehicle speed of the vehicle is reduced to a preset threshold value, the motor brake is cancelled, and the hydraulic brake is used for braking the vehicle.

In one embodiment, the vehicle is braked according to a braking mode corresponding to an interval where a current effective braking stroke is located, and the vehicle is braked according to motor braking and hydraulic braking so as to trigger a braking anti-lock system or an electronic stability control system of the vehicle.

In one embodiment, the vehicle braking device 2000 further comprises an adjustment module (not shown in the figures) for: in the case of triggering a brake anti-lock system or an electronic stability control system of the vehicle, the braking torque of the electric machine brake is preferably adjusted according to the braking demand of the vehicle.

In another embodiment, a vehicle braking device includes a memory and a processor; the memory stores instructions that, when executed by the processor, implement a method as disclosed in any of the foregoing embodiments.

< example II of the apparatus >

One embodiment of the present invention provides a vehicle control apparatus including a memory and a processor; the memory stores instructions that, when executed by the processor, implement a method as disclosed in any of the foregoing embodiments.

< vehicle embodiment >

According to yet another embodiment of the present invention, a vehicle is also provided.

In one aspect, as shown in fig. 5, the vehicle 3000 may include a vehicle braking device as disclosed in any one of the previous embodiments.

On the other hand, as shown in fig. 6, the vehicle 3000' may include the vehicle control device disclosed in any of the foregoing embodiments.

< computer-readable storage Medium embodiment >

Finally, according to a further embodiment of the invention, there is also provided a computer-readable storage medium, on which a computer program is stored, which computer program, when being executed by a processor, carries out the method disclosed in any of the preceding embodiments.

The embodiments of the present invention are described in a progressive manner, and the same and similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, as for the device, vehicle and media embodiments, since they are substantially similar to the method embodiments, the description is relatively simple, and reference may be made to some descriptions of the method embodiments for relevant points.

The foregoing description of specific embodiments of the present invention has been presented. Other embodiments are within the scope of the following claims. In some cases, the actions or steps recited in the claims may be performed in a different order than in the embodiments and still achieve desirable results. In addition, the processes depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In some embodiments, multitasking and parallel processing may also be possible or may be advantageous. The present invention may be a system, method and/or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions embodied therewith for causing a processor to implement various aspects of the present invention.

The computer readable storage medium may be a tangible device that can hold and store the instructions for use by the instruction execution device. The computer readable storage medium may be, for example, but not limited to, an electronic memory device, a magnetic memory device, an optical memory device, an electromagnetic memory device, a semiconductor memory device, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of the computer readable storage medium would include the following: a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a Static Random Access Memory (SRAM), a portable compact disc read-only memory (CD-ROM), a Digital Versatile Disc (DVD), a memory stick, a floppy disk, a mechanical coding device, such as punch cards or in-groove projection structures having instructions stored thereon, and any suitable combination of the foregoing. Computer-readable storage media as used herein is not to be construed as transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., optical pulses through a fiber optic cable), or electrical signals transmitted through electrical wires.

The computer-readable program instructions described herein may be downloaded from a computer-readable storage medium to a respective computing/processing device, or to an external computer or external storage device via a network, such as the internet, a local area network, a wide area network, and/or a wireless network. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. The network adapter card or network interface in each computing/processing device receives computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in a computer-readable storage medium in the respective computing/processing device.

The computer program instructions for carrying out operations of the present invention may be assembler instructions, Instruction Set Architecture (ISA) instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source or object code written in any combination of one or more programming languages, including an object oriented programming language such as Smalltalk, C + + or the like and conventional procedural programming languages, such as the "C" programming language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer through any type of network, including a Local Area Network (LAN) or a Wide Area Network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet service provider). In some embodiments, aspects of the present invention are implemented by personalizing an electronic circuit, such as a programmable logic circuit, a Field Programmable Gate Array (FPGA), or a Programmable Logic Array (PLA), with state information of computer-readable program instructions, which can execute the computer-readable program instructions.

Aspects of the present invention are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer-readable program instructions.

These computer-readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer-readable program instructions may also be stored in a computer-readable storage medium that can direct a computer, programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer-readable medium storing the instructions comprises an article of manufacture including instructions which implement the function/act specified in the flowchart and/or block diagram block or blocks.

The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other devices to cause a series of operational steps to be performed on the computer, other programmable apparatus or other devices to produce a computer implemented process such that the instructions which execute on the computer, other programmable apparatus or other devices implement the functions/acts specified in the flowchart and/or block diagram block or blocks.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. It is well known to those skilled in the art that implementation by hardware, implementation by software, and implementation by a combination of software and hardware are equivalent.

Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein. The scope of the invention is defined by the appended claims.

Claims

1. A vehicle braking method, characterized by comprising:

determining the interval of the current effective braking travel;

2. The method of claim 1, wherein the total available brake stroke of the brake pedal is segmented into a first interval and a second interval, the first interval being between 0 and L1, the second interval being between L2 and L3, 0< L1< L2< L3, the first interval corresponding to a first motor braking mode, and the second interval corresponding to a motor/hydraulic combination braking mode.

3. The method according to claim 2, wherein in the case that the current effective braking stroke is in the first interval, the braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located comprises:

4. The method of claim 3, wherein the target vehicle speed is determined according to the following equation:

5. The method of claim 4, wherein the motor braking demand torque is determined according to the following equation:

6. The method according to claim 2, wherein in the case that the current effective braking stroke is in the second interval, the braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located comprises:

7. The method of claim 2, wherein the total available brake stroke further comprises a third interval between L1-L2, the third interval corresponding to a second motor braking mode.

8. The method according to claim 7, wherein in the case that the current effective braking stroke is in the third interval, the braking the vehicle according to the braking mode corresponding to the interval where the current effective braking stroke is located comprises:

wherein the method further comprises:

9. The method according to claim 7, wherein the interval value corresponding to the third interval is smaller than the interval value corresponding to the first interval, and/or the interval value corresponding to the third interval is smaller than the interval value corresponding to the second interval.

10. The method of claim 1, further comprising, prior to obtaining a current effective braking stroke of a brake pedal of the vehicle:

11. The method according to claim 10, wherein in the case where it is determined that the current brake stroke of the brake pedal is an ineffective brake stroke, the method further comprises:

12. The method of claim 1, wherein in the event that the battery charge level is not below the predetermined value, the method further comprises:

braking the vehicle using hydraulic braking.

13. The method according to any one of claims 1 to 12, wherein the braking of the vehicle according to the braking mode corresponding to the zone in which the current effective braking travel is located is performed according to a braking mode at least including motor braking, so that the current speed of the vehicle is reduced to a predetermined threshold value.

14. The method of claim 13, wherein in the event that the current vehicle speed of the vehicle falls below a predetermined threshold, the method further comprises:

15. The method according to any one of claims 1 to 12, wherein the vehicle is braked according to a braking mode corresponding to an interval in which the current effective braking stroke is located, and the vehicle is braked according to motor braking and hydraulic braking so as to trigger a braking anti-lock system or an electronic stability control system of the vehicle.

16. The method of claim 15, wherein in the event that a brake anti-lock system or an electronic stability control system of the vehicle is triggered, the method further comprises:

17. A vehicle brake device, characterized by comprising:

18. The apparatus of claim 17, wherein the braking module is configured to brake the vehicle according to a corresponding braking manner if the current available braking distance is in a first interval, and includes:

19. The apparatus of claim 17, wherein the braking module is configured to brake the vehicle according to a corresponding braking manner if the current available braking distance is in a second interval, and includes:

20. The apparatus of claim 17, wherein the braking module is configured to brake the vehicle according to a corresponding braking manner if the current available braking stroke is in a third interval, and includes:

wherein the apparatus further comprises:

21. A vehicle braking device comprising a memory and a processor; the memory stores instructions that, when executed by the processor, implement the method of any of claims 1 to 16.

22. A vehicle control apparatus includes a memory and a processor; the memory stores instructions that, when executed by the processor, implement the method of any of claims 1 to 16.

23. A vehicle comprising the vehicle braking apparatus of any one of claims 17 to 21 or comprising the vehicle control apparatus of claim 22.

24. A computer readable storage medium having stored thereon instructions which, when executed by a processor, implement the method of any one of claims 1-16.