CN113442894B

CN113442894B - Method and device for controlling vehicle brake, storage medium and vehicle

Info

Publication number: CN113442894B
Application number: CN202010219520.7A
Authority: CN
Inventors: 谢鸿福; 黄伟; 袁帅; 林威
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2020-03-25
Filing date: 2020-03-25
Publication date: 2022-09-16
Anticipated expiration: 2040-03-25
Also published as: CN113442894A

Abstract

The disclosure relates to a method, a device, a storage medium and a vehicle for controlling vehicle braking, which can obtain the vacuum degree of a vehicle vacuum pump; determining whether the vehicle has a brake fault according to the vacuum degree, wherein the brake fault comprises at least one fault of a relay fault and a vacuum pump system fault; under the condition that the brake fault of the vehicle is determined and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, obtaining the brake depth output by a brake pedal and the current speed of the vehicle; and determining braking feedback torque according to the current vehicle speed and the braking depth, wherein the braking feedback torque is used for controlling the vehicle to brake by combining with the basic braking force corresponding to the braking depth.

Description

Method and device for controlling vehicle brake, storage medium and vehicle

Technical Field

The present disclosure relates to the field of vehicle braking control, and in particular, to a method and an apparatus for controlling vehicle braking, a storage medium, and a vehicle.

Background

At present, when an electric automobile brakes, an electric vacuum pump is mostly adopted to generate negative pressure to meet the vacuum boosting requirement during braking, and a service braking boosting system of the electric automobile is provided in the related technology.

Disclosure of Invention

The invention aims to provide a method and a device for controlling vehicle braking, a storage medium and a vehicle.

In a first aspect, a method for controlling vehicle braking is provided, wherein the vacuum degree of a vehicle vacuum pump is obtained; determining whether the vehicle has a brake fault according to the vacuum degree, wherein the brake fault comprises at least one fault of a relay fault and a vacuum pump system fault; under the condition that the brake fault of the vehicle is determined and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, obtaining the brake depth output by a brake pedal and the current speed of the vehicle; and determining braking feedback torque according to the current vehicle speed and the braking depth, wherein the braking feedback torque is used for controlling the vehicle to brake by combining with basic braking force corresponding to the braking depth.

Optionally, the vehicle comprises a vehicle brake booster, the vehicle brake booster comprising: at least one normally open relay connected to an ECU (Electronic Control Unit) in the vehicle brake assist device; the brake failure comprises the relay failure, and the determining whether the vehicle has the brake failure according to the vacuum degree comprises the following steps: under the condition that the vacuum degree is smaller than a second preset vacuum degree threshold value, determining whether the at least one normally-open relay can not be closed according to a relay return detection signal, and under the condition that the at least one normally-open relay can not be closed, determining that the relay fault occurs in the vehicle; or determining whether an adhered relay exists in the at least one normally open relay according to the relay return detection signal under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, and determining that the relay fault occurs in the vehicle under the condition that the adhered relay exists in the at least one normally open relay; the first preset vacuum degree threshold value is smaller than the second preset vacuum degree threshold value, and the second preset vacuum degree threshold value is smaller than the third preset vacuum degree threshold value.

Optionally, the vehicle brake boosting device further comprises a normally closed relay connected with the ECU, and at least one of the normally open relays is connected with the normally closed relay, and the method further comprises: and under the condition that the stuck relay exists in at least one normally-open relay, controlling the normally-closed relay to be switched off.

Optionally, the failure of the vacuum pump system comprises a vacuum pump air leakage failure or a vacuum pump system failure; the brake failure comprises a vacuum pump leak failure, and before the obtaining the vacuum level of the vehicle vacuum pump, the method further comprises: determining whether the vehicle meets a first preset state condition, and determining whether the duration of time for which the vehicle meets the first preset state condition reaches a first preset time under the condition that the vehicle is determined to meet the first preset state condition; wherein the first preset state condition comprises that the vehicle is in a non-braking state and a vacuum pump of the vehicle is started; the acquiring the vacuum degree of the vehicle vacuum pump comprises the following steps: under the condition that the duration that the vehicle meets the first preset state condition reaches the first preset time, acquiring the current vacuum degree of the vehicle vacuum pump; the determining whether the vehicle has a brake failure according to the vacuum degree comprises: determining whether the current vacuum degree is less than or equal to the first preset vacuum degree threshold value; and under the condition that the current vacuum degree is smaller than or equal to the first preset vacuum degree threshold value, determining that the air leakage fault of the vacuum pump occurs to the vehicle.

Optionally, the brake failure comprises a failure of the vacuum pump system, and the obtaining the vacuum level of the vehicle vacuum pump comprises: collecting a plurality of target vacuum degrees according to a first preset period; the target vacuum degree is the vacuum degree of the vacuum pump respectively acquired at different acquisition moments; the determining whether the vehicle has a brake failure according to the vacuum degree comprises: if the vehicle meets the first preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within second preset time according to a plurality of target vacuum degrees collected within the second preset time; determining that the vehicle has the failure fault of the vacuum pump system under the condition that the vehicle is determined to meet the first preset state condition and the vacuum degree of the vacuum pump is not increased within the second preset time; or if the vehicle meets a second preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within a third preset time according to a plurality of target vacuum degrees collected within the third preset time; under the condition that the vehicle is determined to meet the second preset state condition and the vacuum degree of the vacuum pump is not increased within the third preset time, determining that the vehicle has a failure fault of the vacuum pump system; the second preset state condition comprises that the vehicle is in a braking state, the vacuum pump is started, and any vacuum degree in the target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value.

Optionally, the method further comprises: if the vehicle is determined to have the fault of the vacuum pump system, the vacuum pump is controlled to be started and closed in a circulating mode through a first start-stop proportion according to a second preset period; the first start-stop ratio is the ratio of the time for starting the vacuum pump to the time for closing the vacuum pump in the same second preset period; determining whether the vacuum degree of the vacuum pump is not increased within a fourth preset time, and if the vacuum degree of the vacuum pump is not increased within the fourth preset time, determining that the vacuum pump is damaged; the fourth preset time is the duration of the periodic turning on and off of the vacuum pump.

Optionally, after the determining that the vacuum pump is damaged, the method further comprises: if the vehicle is in a non-braking state at present, controlling the vacuum pump to be closed; or if the vehicle is in a braking state at present, controlling the vacuum pump to be started, and controlling the vacuum pump to be closed when the starting time of the vacuum pump reaches fifth preset time.

Optionally, the method further comprises: when the vacuum pump is determined to be damaged and the vacuum degree is smaller than or equal to the first preset vacuum degree threshold value, acquiring a first vehicle speed of the vehicle and determining whether the vehicle is in an acceleration state; under the condition that the vehicle is determined to be in a non-acceleration state, immediately limiting the speed of the vehicle by taking the first vehicle speed as a vehicle speed upper limit value, and in the process of limiting the speed of the vehicle, if the vehicle is determined to have an acceleration demand, limiting the speed of the vehicle by taking a second vehicle speed as the vehicle speed upper limit value, wherein the second vehicle speed is a real-time vehicle speed acquired when the vehicle is determined to have the acceleration demand under the condition that the first vehicle speed is taken as the vehicle speed upper limit value; under the condition that the vehicle is determined to be in an acceleration state and not to be limited, if the vehicle is switched from the acceleration state to a non-acceleration state, limiting the speed of the vehicle by taking a third vehicle speed as the upper limit value of the vehicle speed, wherein the third vehicle speed is the real-time vehicle speed collected when the vehicle is switched from the acceleration state to the non-acceleration state.

Optionally, before the obtaining the vacuum level of the vehicle vacuum pump, the method further comprises: judging whether the vacuum degree sensor fails or not according to the sampling value range of the vehicle vacuum degree sensor; the acquiring the vacuum degree of the vehicle vacuum pump comprises the following steps: and under the condition that the vacuum degree sensor does not have a fault, acquiring the vacuum degree through the vacuum degree sensor.

Optionally, the method further comprises: and under the condition that the vacuum degree sensor fails, the vacuum pump is controlled to be started and closed in a second starting and stopping proportion cycle mode according to a third preset period, wherein the second starting and stopping proportion is the proportion of the time for starting the vacuum pump to the time for closing the vacuum pump in the same third preset period.

In a second aspect, a vehicle brake booster is provided, which comprises an Electronic Control Unit (ECU), and a vacuum pump, a vacuum degree sensor, a brake pedal and a vehicle speed acquisition device which are respectively connected with the ECU; a brake depth sensor is arranged on the brake pedal; the vacuum degree sensor is used for acquiring the vacuum degree of the vacuum pump; the brake depth sensor is used for acquiring the brake depth of the brake pedal; the vehicle speed acquisition device is used for acquiring the current vehicle speed of the vehicle; the ECU is used for determining whether the vehicle has a brake fault according to the vacuum degree acquired by the vacuum degree sensor, wherein the brake fault comprises at least one fault of a relay fault and a vacuum pump system fault; and under the condition that the brake fault of the vehicle is determined, and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, obtaining the brake depth acquired by the brake depth sensor and the current vehicle speed acquired by the vehicle speed acquisition device, and determining brake feedback torque according to the current vehicle speed and the brake depth, wherein the brake feedback torque is used for controlling the vehicle to brake by combining with basic brake force corresponding to the brake depth.

Optionally, the vehicle brake boosting device further comprises: at least one normally open relay connected with the ECU; the ECU is used for determining whether the at least one normally-open relay cannot be closed according to a relay return detection signal under the condition that the brake fault comprises a relay fault and the vacuum degree is smaller than a second preset vacuum degree threshold value, and determining that the relay fault occurs on the vehicle under the condition that the at least one normally-open relay cannot be closed; or determining whether an adhered relay exists in the at least one normally open relay according to the relay return detection signal under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, and determining that the relay fault occurs in the vehicle under the condition that the adhered relay exists in the at least one normally open relay; the first preset vacuum degree threshold value is smaller than the second preset vacuum degree threshold value, and the second preset vacuum degree threshold value is smaller than the third preset vacuum degree threshold value.

Optionally, the vehicle brake boosting device further comprises a normally closed relay connected with the ECU, at least one normally open relay is connected with the normally closed relay, and the ECU is further configured to control the normally closed relay to be turned off when it is determined that an adhered relay exists in the at least one normally open relay.

Optionally, the failure of the vacuum pump system comprises a vacuum pump air leakage failure or a vacuum pump system failure; the ECU is further used for determining whether the vehicle meets a first preset state condition or not under the condition that the brake failure comprises the air leakage failure of the vacuum pump, and determining whether the duration of the vehicle meeting the first preset state condition reaches a first preset time or not under the condition that the vehicle is determined to meet the first preset state condition; wherein the first preset state condition comprises that the vehicle is in a non-braking state and a vacuum pump of the vehicle is started; the ECU is also used for acquiring the current vacuum degree of the vehicle vacuum pump under the condition that the duration that the vehicle meets the first preset state condition reaches the first preset time; determining whether the current vacuum degree is less than or equal to the first preset vacuum degree threshold value; and under the condition that the current vacuum degree is smaller than or equal to the first preset vacuum degree threshold value, determining that the air leakage fault of the vacuum pump occurs to the vehicle.

Optionally, the ECU is configured to acquire a plurality of target vacuum degrees according to a first preset period when the brake failure includes a failure of the vacuum pump system; the target vacuum degree is the vacuum degree of the vacuum pump respectively acquired at different acquisition moments; if the vehicle meets the first preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within second preset time according to a plurality of target vacuum degrees collected within the second preset time; determining that the vehicle has the failure fault of the vacuum pump system under the condition that the vehicle is determined to meet the first preset state condition and the vacuum degree of the vacuum pump is not increased within the second preset time; or, if the vehicle meets a second preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within a third preset time according to a plurality of target vacuum degrees collected within the third preset time; determining that the vehicle has the failure fault of the vacuum pump system under the condition that the vehicle is determined to meet the second preset state condition and the vacuum degree of the vacuum pump is not increased within the third preset time; the second preset state condition comprises that the vehicle is in a braking state, the vacuum pump is started, and any vacuum degree in the target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value.

Optionally, the ECU is further configured to, if it is determined that the vehicle has the failure of the vacuum pump system, cyclically control the vacuum pump to be turned on and off according to a second preset period by using the first start-stop ratio; the first start-stop ratio is the ratio of the time for starting the vacuum pump to the time for closing the vacuum pump in the same second preset period; determining whether the vacuum degree of the vacuum pump is not increased within a fourth preset time, and if the vacuum degree of the vacuum pump is not increased within the fourth preset time, determining that the vacuum pump is damaged; the fourth preset time is the duration of the periodic turning on and off of the vacuum pump.

Optionally, the ECU is further configured to control the vacuum pump to be turned off if the vehicle is currently in a non-braking state after the determination that the vacuum pump is damaged; or, the controller is further configured to control the vacuum pump to be turned on if the vehicle is currently in a braking state, and control the vacuum pump to be turned off when the turning-on time of the vacuum pump reaches a fifth preset time.

Optionally, the ECU is further configured to, when it is determined that the vacuum pump is damaged and the vacuum degree is less than or equal to the first preset vacuum degree threshold value, acquire a first vehicle speed of the vehicle and determine whether the vehicle is in an acceleration state; under the condition that the vehicle is determined to be in a non-acceleration state, immediately limiting the speed of the vehicle by taking the first vehicle speed as a vehicle speed upper limit value, and in the process of limiting the speed of the vehicle, if the vehicle is determined to have an acceleration demand, limiting the speed of the vehicle by taking a second vehicle speed as the vehicle speed upper limit value, wherein the second vehicle speed is a real-time vehicle speed acquired when the vehicle is determined to have the acceleration demand under the condition that the first vehicle speed is taken as the vehicle speed upper limit value; under the condition that the vehicle is determined to be in an acceleration state and not to be limited, if the vehicle is switched from the acceleration state to a non-acceleration state, limiting the speed of the vehicle by taking a third vehicle speed as the upper limit value of the vehicle speed, wherein the third vehicle speed is the real-time vehicle speed collected when the vehicle is switched from the acceleration state to the non-acceleration state.

Optionally, the ECU is further configured to determine whether the vacuum sensor fails according to a sampling value range of the vehicle vacuum sensor; and under the condition that the vacuum degree sensor does not have a fault, acquiring the vacuum degree through the vacuum degree sensor.

Optionally, the ECU is further configured to cyclically control the vacuum pump to be turned on and off according to a second start-stop ratio in a third preset period when the vacuum degree sensor fails, where the second start-stop ratio is a ratio of time for turning on the vacuum pump to time for turning off the vacuum pump in the same third preset period.

In a third aspect, a computer readable storage medium is provided, on which a computer program is stored, which program, when being executed by a processor, carries out the steps of the method according to the first aspect of the disclosure.

In a fourth aspect, a vehicle is provided that includes the vehicle brake boosting device according to the second aspect of the present disclosure.

By the technical scheme, the vacuum degree of the vacuum pump of the vehicle can be obtained, whether the vehicle has brake failure or not is determined according to the vacuum degree, and the brake failure comprises at least one failure of relay failure and vacuum pump system failure; under the condition that the brake fault of the vehicle is determined and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, obtaining the brake depth output by a brake pedal and the current speed of the vehicle; and determining braking feedback torque according to the current vehicle speed and the braking depth, wherein the braking feedback torque is used for controlling the vehicle to brake in combination with the basic braking force corresponding to the braking depth, so that under the condition that the vehicle is determined to have a relay fault and/or a vacuum pump system fault, when the vehicle has a braking demand, the basic braking force output by a brake pedal can be subjected to torque supplement through the braking feedback torque, the braking torque is increased, the condition that the braking force is insufficient when the vehicle is braked only by depending on the basic braking force output by the brake pedal in the case of the braking fault is avoided, and the effectiveness and the safety of the vehicle in service braking are ensured.

Additional features and advantages of the disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

FIG. 1 is a schematic illustration of a vehicle brake booster according to an exemplary embodiment;

FIG. 2 is a flow chart illustrating a first method of controlling vehicle braking according to an exemplary embodiment;

FIG. 3 is a flow chart illustrating a second method of controlling vehicle braking according to an exemplary embodiment;

FIG. 4 is a schematic diagram illustrating control of a vacuum pump state according to an exemplary embodiment;

FIG. 5 is a flowchart illustrating a third method of controlling vehicle braking according to one exemplary embodiment;

FIG. 6 is a process diagram illustrating safe vehicle speed limit after a vacuum pump is broken, according to an exemplary embodiment;

FIG. 7 is a block diagram illustrating a first vehicle brake assist device according to an exemplary embodiment;

FIG. 8 is a block diagram showing a second vehicle brake assist device in accordance with an exemplary embodiment;

fig. 9 is a block diagram illustrating a configuration of an electronic device according to an example embodiment.

Detailed Description

The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.

The application scene of the present disclosure is introduced first, the present disclosure is mainly applied to a driving brake boosting scene of an electric vehicle, and a related technology provides a driving brake boosting system of an electric vehicle, a storage battery in the system is electrically connected with an electric vacuum pump through a relay group, for example, the relay group may include two commonly used relays and a standby relay which are arranged in parallel, the two relays are respectively in control connection with a vehicle controller in the system, the system may diagnose the relay of the vacuum pump, may also diagnose the gas path leakage degree in the vacuum pump system, and may report a fault and limit the vehicle speed after diagnosing that a relay has a fault or a gas leakage fault of the vacuum pump system, thereby better satisfying the driving control requirements of the electric vehicle.

In the above prior art, the inventor found that, when a fault (such as a relay fault or an air leakage fault) occurs in a vacuum pump system, only fault reporting and vehicle speed limiting are performed, but after the fault occurs in the vacuum pump system, brake assistance cannot be provided, most drivers cannot step down a brake pedal easily, so that the brake force output by the brake pedal cannot meet the current brake requirement, if only the fault is reported and the maximum vehicle speed of a vehicle is limited, in emergency braking, overtaking and other scenes, the driving brake safety cannot be ensured, and in the prior art, if an adhesion fault occurs in a relay appliance, a controller cannot control the power supply of the vacuum pump to be disconnected, which causes the vacuum pump to be always opened, further possibly causes ablation of the vacuum pump, causes a vehicle burning accident, and further, in the prior art, the stalling fault of the vacuum pump cannot be accurately diagnosed, if the vacuum pump has a locked-rotor fault, the controller continues to control the relay to suck and electrify the vacuum pump, so that a motor coil of the vacuum pump generates heat, and the situation of vacuum pump ablation can also occur.

In order to solve the existing problems, the disclosure can obtain the vacuum degree of a vehicle vacuum pump in real time through an ECU in a vehicle brake power assisting device, then judge whether the vehicle has vehicle brake faults such as relay faults or vacuum pump system faults according to the newly obtained vacuum degree, and when the vehicle is determined to have the relay faults and/or the vacuum pump system faults, the vehicle brake power assisting device can supplement the basic brake force output by a brake pedal through brake feedback torque when the vehicle has the brake requirements, so as to increase the brake torque, avoid the situation that the brake force is insufficient when the vehicle brakes only depending on the basic brake force output by the brake pedal when the vehicle has the brake faults, and ensure the effectiveness and the safety when the vehicle is braked in service, furthermore, the vehicle brake power assisting device also comprises a normally closed relay connected with the ECU, the normally open relay is connected with the normally closed relay in series, if there are a plurality of normally open relays, then a plurality of normally open relays are connected in parallel and then connected in series with the normally closed relay. Like this, under the condition of the relay that has the adhesion in confirming at least one this normally open relay, can control this normally closed relay disconnection to unable control vacuum pump power disconnection when having avoided taking place relay adhesion trouble, the vacuum pump opens the appearance that leads to the vacuum pump condition of ablating always.

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

The method for controlling the braking of the vehicle provided by the present disclosure may be performed by an ECU in a vehicle brake booster, and therefore, a system structure of the vehicle brake booster will be described first, fig. 1 is a schematic structural diagram of a vehicle brake booster according to an exemplary embodiment, and as shown in fig. 1, the vehicle brake booster includes a power module (e.g., a 12V battery in fig. 1), an ECU, a normally closed relay (e.g., relay 3 in fig. 1) respectively connected to the ECU, one or more normally open relays (e.g., relay 1 and relay 2 in fig. 1), a vacuum pump, a vacuum sensor, a brake pedal (on which a brake depth sensor and a brake switch are disposed as shown in fig. 1), and a vehicle Speed collecting device, which may be an ESC (Electronic stability Controller, vehicle body Controller), wherein, as shown in fig. 1, a plurality of these normally open relays are connected in parallel and then are connected in series with this normally closed relay (relay 1 and relay 2 are connected in parallel and then are connected in series with relay 3), this power module is this vacuum pump power supply to this power module is connected with this vacuum pump through this normally closed relay and this normally open relay.

It should be noted that, add normally closed relay (relay 3 as shown in fig. 1) in this vehicle braking booster unit to set up this normally closed relay and a plurality of normally open relay after parallelly connected and establish ties, in the circumstances that has the relay of adhesion in confirming a plurality of this normally open relays like this, can control this normally closed relay disconnection, thereby can't control vacuum pump power disconnection when having avoided taking place relay adhesion trouble, the vacuum pump opens the appearance that leads to the vacuum pump ablation condition always.

FIG. 2 is a flow chart illustrating a method of controlling vehicle braking that may be applied to an ECU in a vehicle brake booster, as shown in FIG. 2, according to an exemplary embodiment, comprising the steps of:

in step 201, the vacuum level of a vehicle vacuum pump is acquired.

The vehicle brake booster may include a vacuum pump sensor connected to the ECU, so that the ECU may acquire the vacuum degree through the vacuum degree sensor in this step.

In addition, since the present disclosure may determine whether a brake failure occurs according to a vacuum degree of the vehicle before performing vehicle brake control, and sometimes it is necessary to perform failure diagnosis according to a plurality of vacuum degree values acquired over a period of time, in one possible implementation manner of this step, the vacuum degree may be acquired periodically at a preset period.

In step 202, it is determined whether the vehicle has a brake failure based on the vacuum level.

For example, as shown in fig. 1, if an adhered relay exists in the relay 1 and the relay 2 which are connected in parallel, the brake fault is regarded as the occurrence of the relay adhesion fault, and if the relay 1 and the relay 2 are detected to be incapable of being attracted, the brake fault is regarded as the occurrence of the relay incapable of being attracted; the failure of the vacuum pump system comprises a vacuum pump air leakage failure or a vacuum pump system failure.

In step 203, if it is determined that the vehicle has the brake fault and the vacuum degree is less than or equal to the first preset vacuum degree threshold, the brake depth of the brake pedal and the current vehicle speed of the vehicle are obtained if the vehicle enters a braking state.

Wherein the first preset vacuum degree threshold is a preset minimum vacuum degree threshold. If the vacuum degree of the vacuum pump is larger than the first preset vacuum degree threshold value, the vacuum pump can still provide certain braking assistance, and the vehicle can be controlled to brake only according to the basic braking force output when the vehicle brake pedal is stepped on.

In this step, the ECU may acquire the current vehicle speed through the ESC as shown in fig. 1 and the brake depth through the brake depth sensor as shown in fig. 1.

In step 204, brake torque feedback is determined based on the current vehicle speed and the brake depth.

In one possible implementation manner of the step, a brake feedback torque curve can be calibrated in advance according to experimental data or empirical data, and the curve represents a corresponding relationship between a vehicle speed and a brake depth and the brake feedback torque, so that the brake feedback torque can be obtained by looking up a table according to the current vehicle speed and the brake depth and the brake feedback torque curve.

In this embodiment, after the braking feedback torque is obtained, the vehicle may superimpose the braking feedback torque and the basic braking force, and perform vehicle braking using the superimposed torque as the total braking torque, so that the braking torque of the vehicle when a braking fault occurs may be increased by controlling the vehicle to perform braking by combining the braking feedback torque and the basic braking force, and thus, the assistance may be normally provided for the vehicle braking.

It should be noted that, because the brake pedal is hard to be stepped on when the vacuum degree of the vacuum pump is less than or equal to the first preset vacuum degree threshold, considering that the vehicle has idle torque, the basic braking force transmitted by the brake pedal is partially offset by the idle torque, and the braking force finally applied to the whole vehicle is further reduced, which results in poor deceleration effect under low vehicle speed conditions.

It should be further noted that, based on the method for controlling vehicle braking provided by the present disclosure, in another possible implementation manner, when the ECU sends a fault message, the EPB (Electrical Park Brake) may also receive fault information of the vacuum pump system or fault information of the relay, and recognize the braking intention of the driver to assist deceleration.

In addition, when the brake fault is determined to occur, the method can also be used for respectively recording the brake fault according to different fault types and triggering alarm (such as voice alarm or text prompt alarm) at the same time, so that a driver can pay attention to the occurrence of the brake fault in time and maintain the brake fault in time, and the driving safety of a vehicle is ensured.

By adopting the method, under the condition that the relay fault and/or the vacuum pump system fault of the vehicle are determined, when the vehicle has a braking demand, the braking torque output by the brake pedal can be supplemented by the braking feedback torque, so that the braking torque is increased, the condition that the braking force is insufficient when the braking is carried out only by the braking torque output by the brake pedal when the braking fault occurs is avoided, and the effectiveness and the safety of the vehicle during the service braking are ensured.

Fig. 3 is a flowchart illustrating a method for controlling vehicle braking according to an exemplary embodiment, where a vehicle braking fault shown in the present disclosure includes at least one of a relay fault and a vacuum pump system fault, and fault handling manners corresponding to different fault types are different, and determining whether a relay fault occurs and a fault handling manner of the relay fault occur are described in the embodiment shown in fig. 3, and the method includes the following steps:

in step 301, the ECU of the vehicle collects the vacuum level of the vacuum pump through the vacuum level sensor.

In this step, the vacuum degrees of the vacuum pump at different times may be periodically acquired according to a preset period through the vacuum degree sensor.

It should be noted that, in the method for controlling vehicle braking according to the present embodiment, all methods rely on the vacuum degree collected by the vacuum degree sensor for determination, and if the vacuum degree sensor fails, the reliability of the vacuum pump collected by the vacuum degree sensor is also low, so to improve the accuracy of fault diagnosis, it is necessary to perform fault diagnosis on the vacuum degree sensor first, and on the premise that it is determined that the vacuum degree sensor does not fail, the vehicle braking failure can be accurately diagnosed based on the vacuum degree collected by the vacuum degree sensor.

Therefore, before the step, whether the vacuum degree sensor fails or not can be judged according to the sampling value range of the vehicle vacuum degree sensor, and the vacuum degree is collected through the vacuum degree sensor under the condition that the vacuum degree sensor does not fail.

In one possible implementation, a current calibration signal of a vehicle vacuum sensor may be obtained, and it is determined that the vacuum sensor is not faulty when it is determined that the current calibration signal is within a sampling value range of the vacuum sensor, and it is determined that the vacuum sensor is faulty when it is determined that the current calibration signal is outside the sampling value range of the vacuum sensor.

Under the condition that the vacuum degree sensor fails, the reliability of the vacuum degree acquired by the failed vacuum degree sensor is considered to be low, so that the vacuum pump is not judged to fail under the condition that the vacuum degree sensor fails, and whether the vacuum pump really fails or not can not be accurately judged on the basis of the currently acquired vacuum degree with low reliability.

For example, if the vacuum pump is controlled to be turned on and off every 10 seconds, and if the second start-stop ratio is 1:1, in the same 10 seconds, the vacuum pump may be controlled to be turned on for 5 seconds, and then the vacuum pump may be controlled to be turned off for 5 seconds, which is only an example and is not limited in the present disclosure.

In addition, in the process of controlling the vacuum pump to be turned on and off, the corresponding control process can be completed by controlling the vacuum pump to be powered on or powered off, for example, as shown in fig. 1, in the process of controlling the vacuum pump to be turned on, the relay 1 (or the relay 2) can be controlled to be attracted so as to supply power to the vacuum pump through the storage battery; during the process of controlling the vacuum pump to be turned off, the relay 1 may be controlled to be turned off to control the vacuum pump to be powered down, which is only an example and is not limited by the present disclosure.

In the event that the vacuum sensor is not malfunctioning, it may be determined whether the vehicle is malfunctioning via step 302 below.

In step 302, the ECU determines whether the vehicle has a relay failure through the relay return check signal according to the vacuum degree.

Wherein, this relay trouble can include relay adhesion trouble or the unable actuation trouble of relay, and this vehicle braking booster unit still includes: and at least one normally open relay connected with the ECU, wherein under the condition that the normally open relays are multiple, the normally open relays are mutually connected in parallel.

It should be noted that fig. 1 illustrates two normally open relays, namely, a relay 1 and a relay 2, and in an actual application scenario, three or more normally open relays may also be provided, which is not limited in this disclosure.

Here, as shown in fig. 1, if there is a relay that is adhered in the relay 1 and the relay 2 that are connected in parallel, the battery and the vacuum pump are always in a connected state, the battery continuously supplies power to the vacuum pump, so that the vacuum pump is always turned on, further, the vacuum pump may be ablated, and a burn-in accident may be caused.

In this step, whether the relay failure occurs may be determined in any one of the following two ways:

the first method is as follows: and under the condition that the vacuum degree is smaller than a second preset vacuum degree threshold value, determining whether the at least one normally-open relay can not be closed according to the relay return detection signal, and under the condition that the at least one normally-open relay can not be closed, determining that the relay fault occurs to the vehicle.

In this mode, under a normal condition, if it is determined that the vacuum degree is smaller than the second preset vacuum degree threshold (i.e. the lower limit value of the normal control interval where the vacuum degree of the vacuum pump is located), in order to ensure that normal braking assistance can be provided for vehicle braking, the vacuum pump needs to be controlled to be powered on and work, as shown in fig. 4, the relay 1 (or the relay 2) shown in fig. 1 is controlled to be attracted to control the storage battery to supply power to the vacuum pump, so that the vacuum pump is turned on, when it is determined that the relay 1 cannot be normally attracted, the relay 2 can be switched to be controlled to be attracted, and if it is determined that both the relay 1 and the relay 2 cannot be attracted, it is determined that the relay in the relay fault cannot be attracted.

And in the second mode, under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, whether an adhesive relay exists in the at least one normally-open relay is determined according to the relay return detection signal, and under the condition that the adhesive relay exists in the at least one normally-open relay, the relay adhesion fault of the vehicle is determined.

In this mode, when it is determined that the vacuum degree is greater than or equal to the third preset vacuum degree threshold value (i.e., the upper limit value of the normal control interval where the vacuum degree of the vacuum pump is located), it is described that the vacuum pump can normally provide the braking assistance currently, and the vacuum pump does not need to continue to work, at this time, as shown in fig. 4, the relay in the attraction state in the normally open relay can be controlled to be turned off, so that the vacuum pump is powered off, but if it is determined that there are relays that adhere in a plurality of normally open relays (e.g., there is at least one relay that adheres in relay 1 and relay 2 in fig. 1), the normally open relay cannot be controlled to be turned off in time, so that the vacuum pump is always turned on, there is a risk of vacuum pump ablation, and at this time, it is determined that the relay adhesion fault in the relay fault occurs.

Wherein the first preset vacuum degree threshold is smaller than the second preset vacuum degree threshold, and the second preset vacuum degree threshold is smaller than the third preset vacuum degree threshold; the first preset vacuum degree threshold value is a preset minimum vacuum degree threshold value, and if the vacuum degree of the vacuum pump is greater than the first preset vacuum degree threshold value, the vehicle brake can be controlled only according to the basic brake force output by the vehicle brake pedal; the second preset vacuum degree threshold is a lower limit value of a normal control interval where the vacuum degree of the vacuum pump is located when the vehicle is not in brake failure, and the third preset vacuum degree threshold is an upper limit value of the normal control interval.

It should be noted that, the vehicle brake booster further includes a normally closed relay connected to the ECU, and a plurality of the normally open relays are connected in parallel and then connected in series with the normally closed relay, as shown in fig. 1, the vehicle brake booster relay 3 (i.e., a normally closed relay) is connected in series with the relay 3 after the relay 1 and the relay 2 are connected in parallel.

Consider if there is the relay of adhesion in the confirmed normally open relay, then the supply circuit of vacuum pump can be in the on-state always, power module continues to be the vacuum pump power supply, make the vacuum pump open always (be in operating condition promptly), vacuum pump power supply out of control when taking place the adhesion trouble for avoiding normally open relay, make the vacuum pump open always lead to the vacuum pump ablation, cause the accident of burning a car, in this another embodiment of this disclosure, under the circumstances that has the relay of adhesion in confirming a plurality of these normally open relays, control normally closed relay disconnection (if can control relay 3 disconnection in figure 1), like this, through control normally closed relay disconnection, this vacuum pump outage is controlled.

In addition, the relay return detection signal may be a level signal, and in this embodiment, the ECU may detect whether none of the at least one normally open relay is closed or whether an adhered relay exists through the level signal.

Taking fig. 1 as an example, if neither relay 1 nor relay 2 can be pulled in, the power supply loop of the vacuum pump is in an off state, in which case the ECU acquires the relay return detection signal at the relay return detection pin shown in fig. 1 as a low level signal, if there is an adhesive relay in relay 1 and relay 2, since relay 3 belongs to a normally closed relay, the power supply loop of the vacuum pump is always in an on state, in which case the ECU acquires the relay return detection signal at the relay return detection pin shown in fig. 1 as a high level signal, when the relay is not in fault, in the process of controlling the relay 1 or relay 2 to be pulled in, the ECU acquires the relay return detection signal at the relay return detection pin shown in fig. 1 from a low level signal to a high level signal, in the process of controlling the relay 1 or relay 2 to be turned off, the ECU obtains the relay return check signal from the relay return check pin shown in fig. 1 and changes the high level signal into the low level signal, so that if the ECU obtains the relay return check signal from the relay return check pin shown in fig. 1 and always obtains the low level signal in the process of controlling the relay 1 or the relay 2 to be pulled in, it may be considered that a relay non-pull-in fault occurs, and if the ECU obtains the relay return check signal from the relay return check pin shown in fig. 1 and always obtains the high level signal in the process of controlling the relay 1 or the relay 2 to be disconnected, it may be considered that a relay adhesion fault occurs.

In step 303, if it is determined that the vehicle has a relay fault and the vacuum level is less than or equal to the first preset vacuum level threshold, the ECU obtains the braking depth of the brake pedal and the current vehicle speed of the vehicle if the vehicle enters a braking state.

It is contemplated herein that in the event that the vacuum level of the vacuum pump is greater than the first predetermined vacuum level threshold, vehicle braking may be controlled based solely on the foundation braking force output by the vehicle brake pedal, wherein the basic braking force is a mechanical braking force that is outputted according to a depression depth (i.e., a braking depth) of the brake pedal when the brake pedal is depressed, and therefore, in the case that it is determined that the relay failure has occurred and the vacuum level of the vacuum pump is greater than the first preset vacuum level threshold, if the braking torque of the vehicle is still increased when the vehicle enters a braking state, the braking torque is over-large to cause a safety hazard, and therefore, in this step, if it is determined that the vehicle has a relay failure and the vacuum level is less than or equal to the first preset vacuum level threshold, the subsequent processing of increasing the feedback torque is performed if the vehicle enters a braking state.

In step 304, the ECU determines a brake feedback torque based on the current vehicle speed and the brake depth.

The brake feedback torque is used for controlling the vehicle brake by combining the basic brake force corresponding to the brake depth, and the brake feedback torque is the brake torque which is output by the ECU and used for supplementing the vehicle brake when a brake fault occurs. In a possible implementation manner of this step, a brake feedback torque curve may be pre-calibrated according to experimental data or empirical data, and the curve represents a corresponding relationship between a vehicle speed, a brake depth and the brake feedback torque, so that the brake feedback torque may be obtained by looking up a table according to the current vehicle speed, the brake depth and the brake feedback torque curve.

In step 305, the vehicle is braked according to the brake feedback torque and the basic brake force corresponding to the brake depth.

In this step, the vehicle may superimpose the brake feedback torque and the basic braking force, and perform vehicle braking using the superimposed torque as a total braking torque, so that the braking of the vehicle is controlled by combining the brake feedback torque and the basic braking force, and the braking torque of the vehicle when a braking failure occurs can be increased, thereby normally providing assistance to the vehicle braking.

In addition, when the relay fault is determined to occur, the fault recording method can also be used for respectively recording the fault of the relay according to different fault types and triggering the alarm at the same time, so that a driver can pay attention to the occurrence of the fault in time and maintain the fault in time, and the driving safety of a vehicle is ensured.

By adopting the method, under the condition that the relay fault of the vehicle is determined, when the vehicle has a braking demand, the brake torque output by the brake pedal is supplemented by the brake feedback torque, the brake torque is increased, and when the relay fails, the situation of insufficient braking force occurs when braking is carried out only by the braking torque output by the brake pedal, the effectiveness and the safety of the vehicle during service braking are ensured, and further, the vehicle brake booster further comprises a normally closed relay connected with the ECU, at least one normally open relay is connected with the normally closed relay, thus, under the condition that the normally open relay is determined to have the adhered relay, the normally closed relay can be controlled to be opened, therefore, the situation that the vacuum pump is ablated because the vacuum pump is always started can be avoided when the relay adhesion fault happens and the power supply of the vacuum pump cannot be controlled to be disconnected.

FIG. 5 is a flow chart illustrating a method of controlling vehicle braking according to an exemplary embodiment, which in the embodiment shown in FIG. 5 illustrates the manner in which a determination is made as to whether a vacuum pumping system failure has occurred, and the failure handling of the vacuum pumping system failure, as shown in FIG. 5, includes the steps of:

in step 501, the ECU of the vehicle acquires the vacuum level of the vacuum pump of the vehicle through a vacuum level sensor.

Here, since the vacuum pump system failure includes a vacuum pump air leakage failure and a vacuum pump system failure, for the detection of the vacuum pump air leakage failure, before performing this step 501, it may be determined whether the vehicle satisfies a first preset state condition, and in a case where it is determined that the vehicle satisfies the first preset state condition, it is determined whether a duration that the vehicle satisfies the first preset state condition reaches a first preset time, and in a case where it is determined that the duration that the vehicle satisfies the first preset state condition reaches the first preset time, this step 501 is performed.

Wherein the first preset state condition comprises that the vehicle is in a non-braking state, and a vacuum pump of the vehicle is started (namely the vacuum pump is in an operating state).

For example, it may be determined whether the vehicle is in a non-braking state by detecting a state of a brake pedal, and it may be determined whether the vacuum pump is activated by detecting whether the vacuum pump is powered, for example, if a brake pedal of the vehicle is not pressed, it is determined that the vehicle is in a non-braking state, and if it is determined that the vacuum pump is in a power supply state, it is determined that the vacuum pump is activated, which is only an example and is not limited by the present disclosure.

For the detection of the failure fault of the vacuum pump system, a plurality of target vacuum degrees can be acquired according to a first preset period, wherein the target vacuum degrees are the vacuum degrees of the vacuum pump respectively acquired at different acquisition moments.

It should be noted that before the step is performed, whether the vacuum sensor fails may be determined according to the sampling value range of the vehicle vacuum sensor, and a specific implementation manner may refer to the related description of step 301 in the embodiment shown in fig. 3, which is not described herein again.

After obtaining the vacuum degree of the vacuum pump, determining whether a vacuum pump system fault occurs through the following steps, wherein the vacuum pump system fault is determined whether a vacuum pump air leakage fault occurs through the

steps

502 and 503, and the vacuum pump system failure fault occurs through the step 504;

in step 502, the ECU determines whether the current vacuum level is less than or equal to the first preset vacuum level threshold.

In the case that it is determined that the current vacuum level is less than or equal to the first preset vacuum level threshold, performing step 503;

and under the condition that the current vacuum degree is determined to be less than or equal to the first preset vacuum degree threshold value, determining that the vehicle does not have the vacuum pump air leakage fault.

The first preset vacuum degree threshold is a preset minimum vacuum degree threshold, the vacuum pump air leakage fault generally means that the air intake amount of the vacuum pump is smaller than the air output amount in unit time, and in consideration of the fact that in an actual application scene, when a vehicle is in a non-braking state and the vacuum pump is started (that is, when the first preset state condition is met), if the vacuum pump does not generate the air leakage fault, the current vacuum degree of the vacuum pump detected after continuously meeting the first preset state condition for a period of time is not smaller than or equal to the first preset vacuum degree threshold, therefore, in this embodiment, if the current vacuum degree is determined to be smaller than or equal to the first preset vacuum degree threshold, the vehicle can be determined to generate the vacuum pump air leakage fault.

In step 503, the ECU determines that the vehicle has the vacuum pump leak failure.

In step 504, after a plurality of vacuum degrees are collected, the ECU determines whether the vehicle has a failure fault of the vacuum pump system according to the collected vacuum degrees.

In this step, whether a failure fault of the vacuum pump system occurs can be determined in the following two ways:

firstly, if the vehicle meets the first preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within second preset time according to a plurality of target vacuum degrees collected within the second preset time; and in the case that the vehicle is determined to meet the first preset state condition and the vacuum degree of the vacuum pump is not increased within the second preset time, determining that the vehicle has the failure fault of the vacuum pump system.

Wherein the first preset state condition may include that the vehicle is in a non-braking state and a vacuum pump of the vehicle is turned on.

In an actual application scenario, if a brake pedal of a vehicle is not pressed down and a vacuum pump of the vehicle is turned on (that is, the first preset state condition is met), if a vacuum pump system fails, the vacuum degree of the vacuum pump within the second preset time is increased, but if it is determined that the vacuum degree of the vacuum pump is not increased within the second preset time (the vacuum degree is kept unchanged or decreased) according to a plurality of target vacuum degrees collected within the second preset time, it may be determined that the vacuum pump system fails.

For example, after acquiring a plurality of vacuum degrees according to a first preset period, the ECU may sequentially compare every two adjacent vacuum degrees, determine that the vacuum degree is increased if a subsequent vacuum degree is greater than a previous vacuum degree, and determine that the vacuum degree is not increased if the subsequent vacuum degree is not greater than the previous vacuum degree. For example, the ECU sequentially collects 5 vacuum degrees according to a first preset period, and the vacuum degrees are respectively recorded as a vacuum degree a, a vacuum degree B, a vacuum degree C, a vacuum degree D and a vacuum degree E, and sequentially compares the vacuum degree a with the vacuum degree B, the vacuum degree B with the vacuum degree C, the vacuum degree C with the vacuum degree D, and the vacuum degree D with the vacuum degree E, wherein if the comparison results all indicate that the subsequent vacuum degree is greater than the previous vacuum degree, for example, the vacuum degree D is greater than the vacuum degree C, it is determined that the vacuum degree is increased; if all of the comparison results indicate that the subsequent vacuum level is less than or equal to the previous vacuum level, it is determined that the vacuum level has not increased.

Determining whether the vacuum degree of the vacuum pump is not increased within a third preset time according to a plurality of target vacuum degrees collected within the third preset time if the vehicle meets a second preset state condition; and in the case that the vehicle is determined to meet the second preset state condition and the vacuum degree of the vacuum pump is not increased within the third preset time, determining that the vehicle has the failure fault of the vacuum pump system.

The second preset state condition comprises that the vehicle is in a braking state, the vacuum pump is started, and any vacuum degree in a plurality of target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value.

Considering that in an actual application scenario, if a brake pedal of a vehicle is frequently pressed down, the vacuum degree of a vacuum pump may not be increased within a period of time, but considering that even if the brake pedal is frequently pressed down, the vacuum degree of the vacuum pump does not become smaller than or equal to the first preset vacuum degree threshold value within a period of time in which the vacuum pump continuously works, when the brake pedal is pressed down, it may be determined whether a failure fault of the vacuum pump system occurs in a second mode, that is, different from the first preset state condition in the first mode, in the second mode, the brake pedal of the vehicle is pressed down, that is, the vehicle is in a braking state, and the second preset state condition further includes that any vacuum degree of a plurality of target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value, so that when the vacuum degree of the vacuum pump is not increased due to frequent pressing down of the brake pedal may be avoided, and misjudging the condition of the failure of the vacuum pump system.

In the case that the failure of the vacuum pump system of the vehicle is determined, executing steps 505 to 507, and steps 508 to 513;

in the event that it is determined that the vehicle has not experienced a failure of the vacuum pumping system, the process returns to step 501.

In step 505, if the vacuum degree is less than or equal to the first preset vacuum degree threshold value, the ECU obtains the braking depth of the brake pedal and the current speed of the vehicle if the vehicle enters a braking state.

The first preset vacuum degree threshold is a preset minimum vacuum degree threshold, and if the vacuum degree of the vacuum pump is greater than the first preset vacuum degree threshold, the vehicle brake can be controlled only according to the brake torque output by the vehicle brake pedal, so that even if the vacuum pump system fault is determined to occur, if the vacuum degree of the vacuum pump is greater than the first preset vacuum degree threshold, the brake torque of the vehicle is still increased when the vehicle enters a brake state, and on the contrary, the brake torque is too large to cause potential safety hazards.

In step 506, the ECU determines a brake feedback torque based on the current vehicle speed and the brake depth.

The braking feedback torque is used for controlling the vehicle braking in combination with the basic braking force corresponding to the braking depth, the braking feedback torque is the braking torque which is output by the ECU and used for supplementing the vehicle braking when a braking fault occurs, and the basic braking force is the mechanical braking force which is correspondingly output according to the stepping depth (namely the braking depth) of the braking pedal when the braking pedal is stepped. In a possible implementation manner of this step, a brake feedback torque curve may be pre-calibrated according to experimental data or empirical data, and the curve represents a corresponding relationship between a vehicle speed, a brake depth and the brake feedback torque, so that the brake feedback torque may be obtained by looking up a table according to the current vehicle speed, the brake depth and the brake feedback torque curve.

In step 507, the vehicle is braked according to the brake feedback torque and the basic brake force corresponding to the brake depth.

In addition, when the vacuum degree sensor fault or the vacuum pump system fault is determined to occur, the fault recording method and the fault recording device can respectively record the vacuum degree sensor fault or the vacuum pump system fault according to different fault types and trigger alarm at the same time, so that a driver can pay attention to the occurrence of the fault in time and maintain the fault in time, and the driving safety of a vehicle is guaranteed.

Generally, the vacuum pump system includes components such as a vacuum pump, a connection pipe, a valve, a cylinder, etc., so that a failure of the vacuum pump system may be caused by damage to the vacuum pump due to damage to these components, and therefore, in another embodiment of the present disclosure, after determining that a failure of the vacuum pump system (including a leak failure of the vacuum pump or a failure of the vacuum pump system) occurs, whether the vacuum pump is damaged or not may be further determined by performing

steps

508 and 509.

In step 508, the ECU controls the vacuum pump to turn on and off according to a second preset period through the first start-stop ratio cycle.

And the first start-stop ratio is the ratio of the time for starting the vacuum pump to the time for closing the vacuum pump in the same second preset period.

For example, if the vacuum pump is controlled to be turned on and off every 10 seconds (i.e. one of the second predetermined periods is 10 seconds), and if the first start-stop ratio is 7:3, the vacuum pump may be controlled to be turned on for 7 seconds and then turned off for 3 seconds within the same 10 seconds.

In step 509, the ECU determines whether the vacuum level of the vacuum pump has not increased for a fourth preset time, and if the vacuum level of the vacuum pump has not increased for the fourth preset time, the ECU determines that the vacuum pump is broken.

Wherein the fourth preset time is a duration time for which the vacuum pump is periodically turned on and off.

Here, considering that if the vacuum pump is periodically controlled to be turned on and off in step 508, the vacuum degree of the vacuum pump is raised in the fourth preset time without the vacuum pump being damaged, in this step, the vacuum pump may be cyclically controlled to be turned on and off in the first start-stop ratio in the fourth preset time in the second preset period, and the vacuum degree of the vacuum pump may be periodically collected in the fourth preset time, and the vacuum pump may be determined to be damaged if the vacuum degree of the vacuum pump is not raised in the fourth preset time.

In step 510, the ECU controls the vehicle to enter a pedal control mode after the determination that the vacuum pump is broken.

Considering that the damage of the vacuum pump in the practical application scene can be the locked-rotor fault of the vacuum pump caused by the clamping belt of the vacuum pump, in this case, if the vacuum pump is still controlled to continue to work, the burning accident caused by the ablation of the vacuum pump can be caused, and the situation that the braking force is insufficient can be caused if the vacuum pump system is controlled to stop working immediately when the braking assisting force is required to be provided by the vacuum pump system when the current vehicle is in the braking state can be considered, therefore, in this step, after determining that the vacuum pump is damaged, the vehicle may be controlled to enter a pedal control mode, specifically, if the vehicle is currently in a non-braking state (it may be understood that the vehicle brake pedal is not depressed), under the condition that a vacuum pump system is not required to provide braking assistance, the vacuum pump can be directly controlled to be closed, so that the vacuum pump ablation condition caused by the locked-rotor fault of the vacuum pump is avoided; or, if the vehicle is currently in the braking state, the vacuum pump may be controlled to be turned on, and the vacuum pump may be controlled to be turned off when the turning-on time of the vacuum pump reaches a fifth preset time (e.g., 7 seconds), that is, when it is determined that the vehicle is currently in the braking state, the vacuum pump is not immediately controlled to be turned off, but the vacuum pump is controlled to be turned off when the turning-on time of the vacuum pump reaches the fifth preset time (e.g., 7 seconds), wherein the fifth preset time may be calibrated in advance, so as to ensure that the vacuum pump is not ablated within the fifth preset time even if a stalling fault occurs in the vacuum pump, thereby not only meeting a requirement of providing braking assistance for the vehicle during braking, but also ensuring that the vacuum pump is not ablated due to the stalling fault.

In step 511, when it is determined that the vacuum pump is damaged and the vacuum degree is less than or equal to the first preset vacuum degree threshold value, a first vehicle speed of the vehicle is collected, and it is determined whether the vehicle is in an acceleration state.

In one possible implementation of this step, it may be determined whether the vehicle is in an acceleration state through a throttle depth, for example, if the throttle depth is greater than 0%, it is determined that the vehicle is in an acceleration state, and if the throttle depth is equal to 0%, it is determined that the vehicle is in a non-acceleration state. The first vehicle speed is the current vehicle speed of the vehicle when the vacuum pump is determined to be damaged and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value.

Upon determining that the vehicle is in a non-accelerating state, performing step 512;

upon determining that the vehicle is in an acceleration state, step 513 is performed.

In step 512, the ECU immediately limits the speed of the vehicle using the first vehicle speed as the upper vehicle speed limit.

And the first vehicle speed is taken as the upper vehicle speed limit value to limit the speed of the vehicle, namely, the vehicle is limited to be incapable of exceeding the first vehicle speed.

It should be noted that, in the process of limiting the speed of the vehicle, if it is determined that the vehicle has an acceleration demand, the vehicle is limited by taking the second vehicle speed as the upper limit value of the vehicle speed, where the second vehicle speed is the real-time vehicle speed acquired when the vehicle is determined to have the acceleration demand under the condition that the first vehicle speed is taken as the upper limit value of the vehicle speed. Under the condition that the first vehicle speed is used as the upper limit value of the vehicle speed, the vehicle speed for accelerating the vehicle is limited not to exceed the second vehicle speed so as to form rolling speed limit for the vehicle, so that the vehicle speed of the vehicle can be gradually controlled to tend to safe idling after the damage of the vacuum pump is detected, and the running safety of the vehicle is ensured.

When the accelerator of the subsequent vehicle is pressed down again (namely, the vehicle has an acceleration demand) in the speed limiting process, the speed of the vehicle when the accelerator is pressed down again is taken as the upper limit value of the speed to limit the speed of the vehicle, namely, when the accelerator of the vehicle is pressed down, the speed of the vehicle when the accelerator is pressed down is taken as the upper limit value of the speed to limit the speed of the vehicle until the upper limit value of the speed of the vehicle is idle. For example, FIG. 6 is a schematic diagram illustrating a process for safely limiting vehicle speed after a vacuum pump is broken, as shown in FIG. 6, without limiting vehicle speed during acceleration, when it is determined that the vehicle's accelerator is again depressed, and ultimately to idle.

If it is determined that the vehicle is not speed-limited in step 513, the vehicle is speed-limited using the third vehicle speed as the upper vehicle speed limit when the vehicle is switched from the acceleration state to the non-acceleration state.

And the third vehicle speed is the real-time vehicle speed acquired when the vehicle is switched from an acceleration state to a non-acceleration state.

Here, considering that when the damage of the vacuum pump is detected, the driver may be stepping on the accelerator pedal to control the vehicle speed or overtaking, if the ECU directly limits the vehicle speed at this time, the vehicle may stop suddenly, and a rear-end vehicle rear-end collision or other traffic accidents may occur, so when the damage of the vacuum pump is detected, if the driver is stepping on the accelerator pedal (that is, there is an acceleration demand) and the vehicle itself is not speed-limited, the ECU does not immediately perform speed-limiting processing, and when the driver releases the accelerator pedal (if the accelerator depth is 0%), it indicates that the vehicle is switched from the acceleration state to the non-acceleration state, the vehicle speed when the acceleration state is switched to the non-acceleration state is used as the vehicle speed upper limit value to limit the vehicle speed, and when the driver steps on the accelerator next time, the vehicle speed cannot exceed the vehicle speed upper limit value.

In the embodiment, in the case that it is determined that the vacuum pump is damaged, the vehicle may be controlled to enter the pedal control mode by executing step 410, so as to ensure that the vacuum pump does not suffer from ablation caused by a stalling fault; if it is determined that the vacuum pump is damaged, the vehicle may be safely speed-limited by performing steps 411 to 413, but considering that if the driver is stepping on the accelerator pedal to control the vehicle speed or overtaking at the time, the ECU directly limits the vehicle speed, which may cause a traffic accident such as rear-end collision, and therefore, the vehicle is determined to be in an acceleration state, and the speed-limiting control is not immediately performed, thereby further improving the safety of the vehicle in driving.

It should be noted that the failure handling manners described in the above step 510 and steps 511 to 513 in the case of the two damaged vacuum pumps may be executed in parallel, or may be optionally executed one, which is not limited by the present disclosure, and may be executed simultaneously on the basis of the handling manner (i.e., steps 505 to 507) for increasing the brake feedback torque when the failure of the vacuum pump system is determined.

By adopting the method, under the condition that the vacuum pump system fault of the vehicle is determined, when the vehicle has a braking demand, the basic braking force output by the brake pedal can be subjected to torque compensation through braking feedback torque, the braking torque is increased, the condition that the braking force is insufficient when the vacuum pump system fault occurs and braking is carried out only depending on the basic braking force output by the brake pedal is avoided, the effectiveness and the safety of the vehicle during service braking are ensured, further, when the damage of the vacuum pump is detected, the maximum vehicle speed of the vehicle is limited when the driver has no acceleration demand, and when the driver has the acceleration demand, the vehicle overtaking operation is avoided when the driver completes one-time acceleration demand, and the vehicle speed is limited after the accelerator pedal is released, so that the safe running of the vehicle is ensured.

Fig. 7 is a block diagram illustrating a brake assist apparatus 700 for a vehicle according to an exemplary embodiment, and as shown in fig. 7, the apparatus includes an electronic control unit ECU701, a vacuum pump 702, a vacuum level sensor 703, a brake pedal 704, and a vehicle speed acquisition apparatus 705, which are respectively connected to the ECU 701; a brake depth sensor 7041 is arranged on the brake pedal 704;

wherein, the vacuum sensor 703 is used for collecting the vacuum degree of the vacuum pump; the brake depth sensor 7041 is used for acquiring the brake depth of the brake pedal 704; the vehicle speed acquisition device 705 is used for acquiring the current vehicle speed of the vehicle; the ECU701 is configured to determine whether a brake failure occurs in the vehicle according to the vacuum degree acquired by the vacuum degree sensor 703, where the brake failure includes at least one of a relay failure and a vacuum pump system failure; under the condition that the brake fault of the vehicle is determined and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, the brake depth acquired by the brake depth sensor 7041 and the current vehicle speed acquired by the vehicle speed acquisition device 705 are acquired, and a brake feedback torque is determined according to the current vehicle speed and the brake depth, and the brake feedback torque is used for controlling the vehicle to brake in combination with the basic brake force corresponding to the brake depth. It should be noted that the vehicle speed acquisition device 705 may be an ESC.

Alternatively, fig. 8 is a block diagram illustrating a structure of a vehicle brake boosting device 700 according to the embodiment shown in fig. 7, and as shown in fig. 8, the vehicle brake boosting device 700 further includes: at least one normally open relay 706 connected to the ECU 701; the ECU701 is configured to determine whether the at least one normally-open relay cannot be closed according to the relay return detection signal under the condition that the brake fault includes a relay fault and the vacuum degree is less than a second preset vacuum degree threshold value, and determine that the relay fault occurs in the vehicle under the condition that the at least one normally-open relay cannot be closed; or determining whether an adhered relay exists in the at least one normally open relay according to the relay return detection signal under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, and determining that the relay fault occurs in the vehicle under the condition that the adhered relay exists in the at least one normally open relay;

wherein the first preset vacuum degree threshold is smaller than the second preset vacuum degree threshold, and the second preset vacuum degree threshold is smaller than the third preset vacuum degree threshold.

When the normally open relay includes a plurality of normally open relays, the normally open relays are connected in parallel with each other.

Optionally, as shown in fig. 8, the vehicle brake assisting device 700 further includes a normally closed relay 707 connected to the ECU, at least one of the normally open relays 706 is connected to the normally closed relay 707, and the ECU701 is further configured to control the normally closed relay 707 to open in the case that it is determined that there is an adhered relay in at least one of the normally open relays 706.

Optionally, the vacuum pump system failure comprises a vacuum pump air leakage failure or a vacuum pump system failure; the ECU701 is further configured to determine whether the vehicle satisfies a first preset state condition in a case where the brake failure includes the vacuum pump air leakage failure, and determine whether a duration for which the vehicle satisfies the first preset state condition reaches a first preset time in a case where it is determined that the vehicle satisfies the first preset state condition; wherein the first preset state condition comprises that the vehicle is in a non-braking state, and a vacuum pump of the vehicle is started;

the ECU701 is further configured to obtain a current vacuum degree of the vehicle vacuum pump when it is determined that the duration of time during which the vehicle satisfies the first preset state condition reaches the first preset time; determining whether the current vacuum degree is less than or equal to the first preset vacuum degree threshold value; and under the condition that the current vacuum degree is determined to be less than or equal to the first preset vacuum degree threshold value, determining that the air leakage fault of the vacuum pump occurs to the vehicle.

Optionally, the ECU701 is configured to acquire a plurality of target vacuum degrees according to a first preset period when the braking fault includes a failure fault of the vacuum pump system; the target vacuum degree is the vacuum degree of the vacuum pump respectively acquired at different acquisition moments;

if the vehicle meets the first preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within second preset time according to a plurality of target vacuum degrees collected within the second preset time; determining that the vehicle has a failure fault of the vacuum pump system under the condition that the vehicle is determined to meet the first preset state condition and the vacuum degree of the vacuum pump is not increased within the second preset time; alternatively, the first and second electrodes may be,

if the vehicle meets a second preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within a third preset time according to a plurality of target vacuum degrees collected within the third preset time; under the condition that the vehicle is determined to meet the second preset state condition and the vacuum degree of the vacuum pump is not increased within the third preset time, determining that the vehicle has a failure fault of the vacuum pump system; the second preset state condition comprises that the vehicle is in a braking state, the vacuum pump is started, and any vacuum degree in a plurality of target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value.

Optionally, the ECU701 is further configured to, if it is determined that the vehicle has a failure in the vacuum pump system, cyclically control the vacuum pump to be turned on and off according to a first start-stop ratio according to a second preset period; the first start-stop ratio is the ratio of the time for starting the vacuum pump to the time for closing the vacuum pump in the same second preset period; determining whether the vacuum degree of the vacuum pump is not increased within a fourth preset time, and if the vacuum degree of the vacuum pump is not increased within the fourth preset time, determining that the vacuum pump is damaged; the fourth preset time is a duration of the vacuum pump being periodically turned on and off.

Optionally, the ECU701 is further configured to, after the determination that the vacuum pump is damaged, control the vacuum pump to be turned off if the vehicle is currently in a non-braking state; or, the controller is further configured to control the vacuum pump to be turned on if the vehicle is currently in a braking state, and control the vacuum pump to be turned off when the turning-on time of the vacuum pump reaches a fifth preset time.

Optionally, the ECU701 is further configured to, when it is determined that the vacuum pump is damaged and the vacuum degree is less than or equal to the first preset vacuum degree threshold value, acquire a first vehicle speed of the vehicle and determine whether the vehicle is in an acceleration state; under the condition that the vehicle is determined to be in a non-acceleration state, immediately taking the first vehicle speed as a vehicle speed upper limit value to limit the speed of the vehicle, and in the process of limiting the speed of the vehicle, if the vehicle is determined to have an acceleration demand, taking a second vehicle speed as the vehicle speed upper limit value to limit the speed of the vehicle, wherein the second vehicle speed is a real-time vehicle speed acquired when the vehicle is determined to have the acceleration demand under the condition that the first vehicle speed is taken as the vehicle speed upper limit value; under the condition that the vehicle is determined to be in an acceleration state and not to be limited, if the vehicle is switched from the acceleration state to a non-acceleration state, limiting the speed of the vehicle by taking a third vehicle speed as the upper limit value of the vehicle speed, wherein the third vehicle speed is the real-time vehicle speed collected when the vehicle is switched from the acceleration state to the non-acceleration state.

Optionally, the ECU701 is further configured to determine whether the vacuum sensor fails according to the sampling value range of the vehicle vacuum sensor; in the case where the vacuum degree sensor does not fail, the vacuum degree is collected by the vacuum degree sensor.

Optionally, the ECU701 is further configured to, when the vacuum degree sensor fails, cyclically control the vacuum pump to be turned on and off according to a second start-stop ratio according to a third preset period, where the second start-stop ratio is a ratio of time for turning on the vacuum pump to time for turning off the vacuum pump in the same third preset period.

With regard to the apparatus in the above-described embodiment, the specific manner in which each module performs the operation has been described in detail in the embodiment related to the method, and will not be elaborated here.

By adopting the device, under the condition that the relay fault and/or the vacuum pump system fault of the vehicle are determined, when the vehicle has a braking demand, the basic braking force output by the brake pedal can be supplemented by the braking feedback torque, the braking torque is increased, the condition that the braking force is insufficient when the braking is carried out only by depending on the basic braking force output by the brake pedal when the braking fault occurs is avoided, and the effectiveness and the safety of the vehicle during service braking are ensured.

Fig. 9 is a block diagram illustrating an electronic device 900 in accordance with an example embodiment. As shown in fig. 9, the electronic device 900 may include: a processor 901 and a memory 902. The electronic device 900 may also include one or more of a multimedia component 903, an input/output (I/O) interface 904, and a communications component 905.

The processor 901 is configured to control the overall operation of the electronic device 900 to complete all or part of the steps in the above-described method for controlling the braking of the vehicle. The memory 902 is used to store various types of data to support operation of the electronic device 900, such as instructions for any application or method operating on the electronic device 900 and application-related data, such as contact data, transmitted and received messages, pictures, audio, video, and the like. The Memory 902 may be implemented by any type of volatile or non-volatile Memory device or combination thereof, such as Static Random Access Memory (SRAM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Erasable Programmable Read-Only Memory (EPROM), Programmable Read-Only Memory (PROM), Read-Only Memory (ROM), magnetic Memory, flash Memory, magnetic disk or optical disk. The multimedia component 903 may include a screen and an audio component. Wherein the screen may be, for example, a touch screen and the audio component is used for outputting and/or inputting audio signals. For example, the audio component may include a microphone for receiving external audio signals. The received audio signal may further be stored in the memory 902 or transmitted through the communication component 905. The audio assembly further comprises at least one speaker for outputting audio signals. The I/O interface 904 provides an interface between the processor 901 and other interface modules, such as a keyboard, mouse, buttons, etc. These buttons may be virtual buttons or physical buttons. The communication component 905 is used for wired or wireless communication between the electronic device 900 and other devices. Wireless Communication, such as Wi-Fi, bluetooth, Near Field Communication (NFC), 2G, 3G, 4G, NB-IOT, eMTC, or other 5G, etc., or a combination of one or more of them, which is not limited herein. The corresponding communication component 905 may thus include: Wi-Fi module, Bluetooth module, NFC module, etc.

In an exemplary embodiment, the electronic Device 900 may be implemented by one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), controllers, microcontrollers, microprocessors, or other electronic components for performing the above-described method of controlling vehicle braking.

In another exemplary embodiment, a computer readable storage medium comprising program instructions which, when executed by a processor, implement the steps of the above-described method of controlling vehicle braking is also provided. For example, the computer readable storage medium may be the memory 902 described above including program instructions executable by the processor 901 of the electronic device 900 to perform the method of controlling vehicle braking described above.

In another exemplary embodiment, a computer program product is also provided, which comprises a computer program executable by a programmable apparatus, the computer program having code portions for performing the above-described method of controlling braking of a vehicle when executed by the programmable apparatus.

The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.

It should be noted that, in the foregoing embodiments, various features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various combinations that are possible in the present disclosure are not described again.

In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.

Claims

1. A method of controlling vehicle braking, the method comprising:

obtaining the vacuum degree of a vehicle vacuum pump;

determining whether the vehicle has a brake fault according to the vacuum degree, wherein the brake fault comprises at least one fault of a relay fault and a vacuum pump system fault;

under the condition that the brake fault of the vehicle is determined and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, the brake depth of a brake pedal and the current speed of the vehicle are obtained;

determining braking feedback torque according to the current vehicle speed and the braking depth, wherein the braking feedback torque is used for controlling the vehicle to brake in combination with basic braking force corresponding to the braking depth;

the vehicle includes a vehicle brake boosting device, the vehicle brake boosting device including: at least one normally open relay connected with an Electronic Control Unit (ECU) in the vehicle brake power assisting device;

the brake fault comprises a relay fault, and the determining whether the vehicle has the brake fault according to the vacuum degree comprises:

under the condition that the vacuum degree is smaller than a second preset vacuum degree threshold value, determining whether the at least one normally-open relay can not be closed according to a relay return detection signal, and under the condition that the at least one normally-open relay can not be closed, determining that the relay fault occurs in the vehicle; alternatively, the first and second electrodes may be,

under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, whether an adhered relay exists in the at least one normally-open relay is determined according to the relay return detection signal, and under the condition that the adhered relay exists in the at least one normally-open relay, the relay fault of the vehicle is determined;

the first preset vacuum degree threshold value is smaller than the second preset vacuum degree threshold value, and the second preset vacuum degree threshold value is smaller than the third preset vacuum degree threshold value.

2. The method of claim 1, wherein the vehicle brake boosting device further comprises a normally closed relay connected to the ECU, at least one of the normally open relays being connected to the normally closed relay, the method further comprising:

and under the condition that the stuck relay exists in at least one normally-open relay, controlling the normally-closed relay to be switched off.

3. The method of claim 1, wherein the vacuum pump system failure comprises a vacuum pump leak failure or a vacuum pump system failure; the brake failure comprises a vacuum pump air leakage failure, and before the obtaining of the vacuum degree of the vehicle vacuum pump, the method further comprises:

determining whether the vehicle meets a first preset state condition, and determining whether the duration of time for which the vehicle meets the first preset state condition reaches a first preset time under the condition that the vehicle is determined to meet the first preset state condition; wherein the first preset state condition comprises that the vehicle is in a non-braking state and a vacuum pump of the vehicle is started;

the acquiring the vacuum degree of the vehicle vacuum pump comprises the following steps:

under the condition that the duration that the vehicle meets the first preset state condition reaches the first preset time, acquiring the current vacuum degree of the vehicle vacuum pump;

the determining whether the vehicle has a brake failure according to the vacuum degree comprises:

determining whether the current vacuum degree is less than or equal to the first preset vacuum degree threshold value;

and under the condition that the current vacuum degree is determined to be smaller than or equal to the first preset vacuum degree threshold value, determining that the air leakage fault of the vacuum pump occurs to the vehicle.

4. The method of claim 3, wherein the brake failure comprises a failure of the vacuum pump system, the obtaining a vacuum level of a vehicle vacuum pump comprising:

collecting a plurality of target vacuum degrees according to a first preset period; the target vacuum degree is the vacuum degree of the vacuum pump respectively acquired at different acquisition moments;

if the vehicle meets the first preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within second preset time according to a plurality of target vacuum degrees collected within the second preset time; determining that the vehicle has the failure fault of the vacuum pump system under the condition that the vehicle is determined to meet the first preset state condition and the vacuum degree of the vacuum pump is not increased within the second preset time; alternatively, the first and second electrodes may be,

if the vehicle meets a second preset state condition, determining whether the vacuum degree of the vacuum pump is not increased within a third preset time according to a plurality of target vacuum degrees collected within the third preset time; under the condition that the vehicle is determined to meet the second preset state condition and the vacuum degree of the vacuum pump is not increased within the third preset time, determining that the vehicle has a failure fault of the vacuum pump system; the second preset state condition comprises that the vehicle is in a braking state, the vacuum pump is started, and any vacuum degree in the target vacuum degrees collected in the third preset time is smaller than or equal to the first preset vacuum degree threshold value.

5. The method according to any one of claims 1 to 4, further comprising:

if the vehicle is determined to have the fault of the vacuum pump system, the vacuum pump is controlled to be started and closed in a circulating mode through a first start-stop proportion according to a second preset period; the first start-stop ratio is the ratio of the time for starting the vacuum pump to the time for closing the vacuum pump in the same second preset period;

determining whether the vacuum degree of the vacuum pump is not increased within a fourth preset time, and if the vacuum degree of the vacuum pump is not increased within the fourth preset time, determining that the vacuum pump is damaged; the fourth preset time is the duration of the periodic turning on and off of the vacuum pump.

6. The method of claim 5, wherein after the determining that the vacuum pump is broken, the method further comprises:

if the vehicle is in a non-braking state at present, controlling the vacuum pump to be closed; alternatively, the first and second electrodes may be,

and if the vehicle is in a braking state at present, controlling the vacuum pump to be started, and controlling the vacuum pump to be closed when the starting time of the vacuum pump reaches fifth preset time.

7. The method of claim 5, further comprising:

when the vacuum pump is determined to be damaged and the vacuum degree is smaller than or equal to the first preset vacuum degree threshold value, acquiring a first vehicle speed of the vehicle and determining whether the vehicle is in an acceleration state;

under the condition that the vehicle is determined to be in a non-acceleration state, immediately limiting the speed of the vehicle by taking the first vehicle speed as a vehicle speed upper limit value, and in the process of limiting the speed of the vehicle, if the vehicle is determined to have an acceleration demand, limiting the speed of the vehicle by taking a second vehicle speed as the vehicle speed upper limit value, wherein the second vehicle speed is a real-time vehicle speed acquired when the vehicle is determined to have the acceleration demand under the condition that the first vehicle speed is taken as the vehicle speed upper limit value;

under the condition that the vehicle is determined to be in an acceleration state and not to be limited, if the vehicle is switched from the acceleration state to a non-acceleration state, limiting the speed of the vehicle by taking a third vehicle speed as the upper limit value of the vehicle speed, wherein the third vehicle speed is the real-time vehicle speed collected when the vehicle is switched from the acceleration state to the non-acceleration state.

8. The method of claim 1, wherein prior to said obtaining a vacuum level of a vehicle vacuum pump, the method further comprises:

judging whether the vacuum degree sensor fails or not according to the sampling value range of the vehicle vacuum degree sensor;

and under the condition that the vacuum degree sensor does not have a fault, acquiring the vacuum degree through the vacuum degree sensor.

9. The method of claim 8, further comprising:

and under the condition that the vacuum degree sensor fails, the vacuum pump is controlled to be started and closed in a second starting and stopping proportion cycle mode according to a third preset period, wherein the second starting and stopping proportion is the proportion of the time for starting the vacuum pump to the time for closing the vacuum pump in the same third preset period.

10. The vehicle brake booster is characterized by comprising an Electronic Control Unit (ECU), a vacuum pump, a vacuum degree sensor, a brake pedal and a vehicle speed acquisition device, wherein the vacuum pump, the vacuum degree sensor, the brake pedal and the vehicle speed acquisition device are respectively connected with the ECU; a brake depth sensor is arranged on the brake pedal;

the vacuum degree sensor is used for acquiring the vacuum degree of the vacuum pump;

the brake depth sensor is used for acquiring the brake depth of the brake pedal;

the vehicle speed acquisition device is used for acquiring the current vehicle speed of the vehicle;

the ECU is used for determining whether the vehicle has a brake fault according to the vacuum degree acquired by the vacuum degree sensor, wherein the brake fault comprises at least one fault of a relay fault and a vacuum pump system fault; under the condition that the brake fault of the vehicle is determined, and the vacuum degree is smaller than or equal to a first preset vacuum degree threshold value, if the vehicle enters a brake state, the brake depth acquired by the brake depth sensor and the current vehicle speed acquired by the vehicle speed acquisition device are acquired, and a brake feedback torque is determined according to the current vehicle speed and the brake depth, wherein the brake feedback torque is used for controlling the vehicle to brake by combining with a basic brake force corresponding to the brake depth;

the vehicle brake boosting device further comprises: at least one normally open relay connected with the ECU; the ECU is configured to, in the event that the braking failure comprises a relay failure,

under the condition that the vacuum degree is greater than or equal to a third preset vacuum degree threshold value, whether an adhered relay exists in the at least one normally-open relay is determined according to the relay return detection signal, and under the condition that the adhered relay exists in the at least one normally-open relay, the relay fault of the vehicle is determined; the first preset vacuum degree threshold value is smaller than the second preset vacuum degree threshold value, and the second preset vacuum degree threshold value is smaller than the third preset vacuum degree threshold value.

11. The apparatus of claim 10, wherein the vehicle brake booster further comprises a normally closed relay connected to the ECU, at least one of the normally open relays being connected to the normally closed relay, the ECU being further configured to control the normally closed relay to open if it is determined that there is an stuck relay in at least one of the normally open relays.

12. A computer-readable storage medium, on which a computer program is stored which, when being executed by a processor, carries out the steps of the method according to any one of claims 1 to 9.

13. A vehicle comprising a vehicle brake boosting device according to claim 10 or 11.