CN113460014B - Control method for deceleration of brake tail end of electric automobile - Google Patents
Control method for deceleration of brake tail end of electric automobile Download PDFInfo
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- CN113460014B CN113460014B CN202110858429.4A CN202110858429A CN113460014B CN 113460014 B CN113460014 B CN 113460014B CN 202110858429 A CN202110858429 A CN 202110858429A CN 113460014 B CN113460014 B CN 113460014B
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000011084 recovery Methods 0.000 claims abstract description 103
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- 230000007246 mechanism Effects 0.000 claims description 12
- 238000006073 displacement reaction Methods 0.000 claims description 10
- 230000009467 reduction Effects 0.000 claims description 10
- 230000001172 regenerating effect Effects 0.000 claims description 8
- 230000001960 triggered effect Effects 0.000 claims description 6
- 230000004044 response Effects 0.000 claims description 4
- 238000005452 bending Methods 0.000 abstract description 2
- 230000008569 process Effects 0.000 description 7
- 230000035939 shock Effects 0.000 description 7
- 239000000725 suspension Substances 0.000 description 5
- 230000006870 function Effects 0.000 description 4
- 230000003993 interaction Effects 0.000 description 3
- 230000010355 oscillation Effects 0.000 description 2
- 230000036461 convulsion Effects 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
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- 239000000446 fuel Substances 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/66—Electrical control in fluid-pressure brake systems
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L7/00—Electrodynamic brake systems for vehicles in general
- B60L7/10—Dynamic electric regenerative braking
- B60L7/18—Controlling the braking effect
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/18—Propelling the vehicle
- B60W30/18009—Propelling the vehicle related to particular drive situations
- B60W30/18109—Braking
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/18—Propelling the vehicle
- B60W30/18009—Propelling the vehicle related to particular drive situations
- B60W30/18109—Braking
- B60W30/18127—Regenerative braking
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/72—Electric energy management in electromobility
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- Transportation (AREA)
- Mechanical Engineering (AREA)
- Automation & Control Theory (AREA)
- Power Engineering (AREA)
- Regulating Braking Force (AREA)
Abstract
The invention discloses a method for controlling the deceleration of a brake tail end of an electric automobile, which comprises the following steps: in a decoupling state, calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal; when braking, obtaining the travel of a brake pedal; and controlling the braking deceleration through the energy recovery torque and/or the mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the acquired stroke of the brake pedal. According to the control method for the deceleration of the braking tail end of the electric automobile, the braking deceleration is controlled through the energy recovery torque and the mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the obtained stroke of the brake pedal, the mild deceleration and the stable braking of the automobile are realized, the problem of braking comfort can be improved to the greatest extent, and the discomfort brought by bending the whole automobile forward and backward during the braking is avoided.
Description
Technical Field
The invention relates to the technical field of electric automobiles, in particular to a control method for the deceleration of a brake tail end of an electric automobile.
Background
In the driving process, a driver realizes deceleration braking by stepping on the brake pedal, and controls the deceleration of the vehicle by stepping on different force and different travel of the brake pedal, thereby achieving the purpose of controlling the vehicle. In the braking process, due to inertia factors, the load of the vehicle can be transferred to the front axle, so that the posture of the vehicle is unstable and the vehicle can oscillate back and forth. Human perception is particularly sensitive to such oscillations or deceleration in the longitudinal direction of the vehicle, and if the difference is too great, it will feel very uncomfortable and have a sensation of motion sickness.
At present, most vehicles inevitably have oscillation motion in the braking process. Especially when the driver brakes and makes the vehicle stop, when the vehicle is about to stop soon, this kind of shock is bored and is felt very seriously, and some motorcycle type suspension systems do not adjust well, can vibrate many times, until whole energy is absorbed by suspension system. Therefore, poor control of the brake pedal can affect the comfort of braking. Therefore, some old drivers can control the brake pedal well (for example, recover a little) during the driving process, especially when the vehicle is braked quickly to stop, and the shock is reduced to improve the braking comfort.
Therefore, a method for controlling the deceleration of the braking end of the electric vehicle is needed.
Disclosure of Invention
The invention aims to provide a method for controlling the deceleration of the brake tail end of an electric automobile, which aims to solve the problems in the prior art and can relieve the brake discomfort caused by the shock and the frustration of the whole automobile when a driver is about to brake.
The invention provides a method for controlling the deceleration of a brake tail end of an electric automobile, which comprises the following steps:
in a decoupling state, calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal;
when braking, obtaining the travel of a brake pedal;
and controlling braking deceleration through energy recovery torque and/or mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the acquired stroke of the brake pedal.
The method for controlling the deceleration of the braking end of the electric vehicle, wherein preferably, in the decoupled state, the calibrating the variation relationship of the mechanical hydraulic pressure along with the stroke of the brake pedal specifically includes:
detecting the travel of a brake pedal when a driver steps on the brake pedal by an intelligent brake system and by using a displacement sensor arranged on the brake pedal;
when the energy recovery torque is zero, detecting mechanical hydraulic pressure generated in the intelligent brake system when a driver steps on a brake pedal through the intelligent brake system by using a hydraulic sensor;
and calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal according to the detected stroke of the brake pedal and the corresponding mechanical hydraulic pressure to obtain the MAP table.
The method for controlling the deceleration of the braking end of the electric vehicle as described above, wherein preferably, the obtaining of the brake pedal stroke specifically includes:
the travel of the driver stepping on the brake pedal is obtained by the intelligent brake system and the displacement sensor arranged on the brake pedal.
The method for controlling the deceleration of the braking end of the electric vehicle as described above, wherein preferably, the controlling the braking deceleration by the energy recovery torque and/or the mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the acquired stroke of the brake pedal includes:
if the energy recovery torque request state is normal, responding to an energy recovery torque request sent by an intelligent braking system, and outputting an actual braking recovery torque by the vehicle control unit;
and if the energy recovery torque request state bit is invalid, the actual braking recovery torque output by the vehicle controller is zero, the intelligent braking system builds pressure according to the calibration result of the mechanical hydraulic pressure, and the braking speed is reduced through the mechanical hydraulic pressure.
The method for controlling deceleration of the braking end of the electric vehicle as described above, wherein preferably, if the energy recovery torque request status bit is normal, the vehicle controller outputs the actual braking recovery torque in response to the energy recovery torque request issued by the intelligent braking system, and specifically includes:
when the braking request is smaller than the regenerative braking capacity of the motor, the vehicle control unit compares the braking recovery torque and the sliding recovery torque which can be output by the intelligent braking system, takes a larger value as the actual braking recovery torque, and performs braking deceleration through the energy recovery torque;
when the braking request is larger than the regenerative braking capacity of the motor, the whole vehicle controller sets the torque limit value to be zero, and at the moment, the intelligent braking system builds pressure according to the calibration result of the mechanical hydraulic pressure and performs braking and speed reduction through the mechanical hydraulic pressure.
In the method for controlling deceleration at braking end of electric vehicle as described above, preferably, if the energy recovery torque request status bit is normal, the vehicle control unit outputs the actual braking recovery torque in response to the energy recovery torque request from the intelligent braking system, further comprising:
when the vehicle is about to stop, the energy recovery torque is reduced or the hydraulic braking force is reduced by the terminal deceleration control system.
The method for controlling the braking terminal deceleration of the electric vehicle as described above, wherein preferably, the terminal deceleration control system is triggered by a physical button or a function switch provided on an instrument panel or a vehicle-mounted entertainment information system.
The method for controlling the braking terminal deceleration of the electric vehicle as described above, wherein preferably, when the vehicle is about to stop, the reducing the energy recovery torque or the reducing the hydraulic braking force by the terminal deceleration control system specifically includes:
when a driver brakes, if the current energy recovery torque can meet the deceleration required by the travel of a brake pedal, the intelligent brake system does not push the internal mechanism to generate mechanical hydraulic pressure, and the intelligent brake system brakes and decelerates through the energy recovery torque;
when the vehicle speed is smaller than the preset speed threshold value, the intelligent braking system reduces the energy recovery torque in a gradient manner according to the current deceleration and the brake pedal travel of the whole vehicle.
The method for controlling the braking terminal deceleration of the electric vehicle as described above, wherein preferably, when the vehicle is about to stop, the reducing the energy recovery torque or the reducing the hydraulic braking force by the terminal deceleration control system specifically includes:
when a driver brakes, if the current energy recovery torque does not meet the deceleration required by the travel of a brake pedal, the mechanical hydraulic pressure generated by pushing hydraulic pressure through the energy recovery torque and an internal mechanism of the intelligent brake system is used for braking and decelerating;
when the vehicle speed is smaller than the preset speed threshold value, the intelligent braking system backs off partial stroke of an internal mechanism of the intelligent braking system according to the current deceleration and the brake pedal stroke of the whole vehicle, so that the mechanical hydraulic pressure generated by hydraulic braking is reduced.
The invention provides a control method of brake tail end deceleration of an electric automobile, which controls brake deceleration through energy recovery torque and mechanical hydraulic pressure according to a calibration result of the mechanical hydraulic pressure and an obtained brake pedal stroke, realizes mild deceleration and smooth brake stopping of the automobile, can improve the problem of brake comfort to the greatest extent, and avoids uncomfortable feeling brought to people by bending the whole automobile forwards and backwards during brake stopping.
Drawings
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be further described with reference to the accompanying drawings, in which:
fig. 1 is a flowchart of an embodiment of a method for controlling deceleration of a brake end of an electric vehicle according to the present invention.
Detailed Description
Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the disclosure, its application, or uses. The present disclosure may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. It should be noted that: the relative arrangement of parts and steps, the composition of materials, numerical expressions and numerical values set forth in these embodiments are to be construed as merely illustrative, and not as limitative, unless specifically stated otherwise.
As used in this disclosure, "first", "second": and the like, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element preceding the word comprises the element listed after the word, and does not exclude the possibility that other elements may also be included. "upper", "lower", and the like are used merely to indicate relative positional relationships, and when the absolute position of the object being described is changed, the relative positional relationships may also be changed accordingly.
In the present disclosure, when a specific component is described as being located between a first component and a second component, there may or may not be intervening components between the specific component and the first component or the second component. When it is described that a specific component is connected to other components, the specific component may be directly connected to the other components without having an intervening component, or may be directly connected to the other components without having an intervening component.
All terms (including technical or scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs unless specifically defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate.
Electronic braking, namely an intelligent brake system (EBS), is often used in the braking system of the current new energy electric vehicle. By adopting the intelligent braking system, the speed can be reduced by combining the energy recovery of the whole driving motor during braking.
At present, the braking system of most fuel vehicles or partial new energy electric vehicles realizes braking deceleration through a vacuum booster, if a brake pedal is stepped on, the pedal can push a vacuum booster pump, and then the vacuum booster pump pushes a brake master cylinder to generate brake hydraulic pressure to control the brake of a brake caliper. This deceleration control scheme is fixed. When the vehicle is optimized to brake and decelerate, the damping of the suspension system is controlled and the support is lifted by adjusting the suspension system, so that the suspension system is not lifted by being too soft. In another scheme, when the vehicle brakes and decelerates, partial hydraulic pressure is sucked back through a motor of an electronic stability control system (ESC) of the vehicle, so that the braking pressure of a wheel cylinder is reduced, and the vehicle shock is reduced.
The existing vacuum boosting system has the advantages that the braking force and the pedal stroke are preset, the relationship among the pedal force, the pedal displacement and the deceleration of a vehicle body when the pedal is stepped on cannot be changed, a driver can only adapt to the braking system and get used to the braking system, and then the pedal force and the pedal displacement are accurately controlled in the actual use process. And such control is highly demanding on the driver. When replacing a vehicle, the driver needs to adapt to the pedal feel of the vehicle again.
When the ESC brakes and decelerates, a motor is used for sucking back part of hydraulic pressure to reduce the braking pressure of the wheel cylinder, and in the scheme, the ESC motor generates noise of the motor in the process of sucking back, and simultaneously has vibration, so that NVH (noise, vibration and harshness) is not good. And more importantly, the scheme has low precision, hydraulic control is not accurate, the deceleration of the whole vehicle fluctuates, and even if the suck-back is too much, the driver can feel no brake. But the responsiveness of the ESC motor operation is also relatively sluggish.
As shown in fig. 1, in the actual implementation process, the method for controlling the deceleration of the braking end of the electric vehicle provided in this embodiment specifically includes the following steps:
and step S1, calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal in the decoupling state.
The decoupling state refers to the fact that the brake pedal stroke and the mechanical hydraulic pressure are not directly related in a physical mechanism, and the relation between the brake pedal stroke and the mechanical hydraulic pressure is determined through calibration.
In an embodiment of the method for controlling the braking end deceleration of the electric vehicle according to the present invention, the step S1 may specifically include:
and step S11, detecting the travel of the brake pedal when the driver steps on the brake pedal by the intelligent brake system and by using a displacement sensor arranged on the brake pedal.
Step S12, when the energy recovery torque is zero, detecting mechanical hydraulic pressure generated in the intelligent braking system when a driver steps on a brake pedal through the intelligent braking system by using a hydraulic sensor;
and step S13, calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal according to the detected stroke of the brake pedal and the corresponding mechanical hydraulic pressure, and obtaining a MAP table.
And step S2, acquiring the stroke of the brake pedal during braking.
Specifically, the travel of the driver for stepping on the brake pedal is obtained through an intelligent brake system by using a displacement sensor arranged on the brake pedal. After the brake pedal travel is obtained, the deceleration can be distributed to the whole brake travel according to the brake pedal travel.
And step S3, controlling braking deceleration through energy recovery torque and/or mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the acquired stroke of the brake pedal.
The energy recovery torque is torque generated by the reverse rotation of the motor, namely the charging of the battery, the mechanical hydraulic pressure is generated by pushing a mechanism in the intelligent brake system to generate mechanical hydraulic pressure, and the mechanical hydraulic brake generates friction force, so that the braking is provided for the whole vehicle. In an embodiment of the method for controlling the braking end deceleration of the electric vehicle according to the present invention, the step S3 may specifically include:
and step S31, responding to the energy recovery torque request sent by the intelligent braking system if the energy recovery torque request state is normal, and outputting the actual braking recovery torque by the vehicle control unit.
The vehicle control unit adjusts the output torque according to the magnitude and direction (for example, forward rotation and reverse rotation) of the energy recovery torque request.
In an embodiment of the method for controlling the braking end deceleration of the electric vehicle according to the present invention, the step S31 may specifically include:
and step S311, when the braking request is smaller than the regenerative braking capacity of the motor, comparing the braking recovery torque and the sliding recovery torque which can be output by the intelligent braking system by the vehicle control unit, taking a larger value as the actual braking recovery torque, and performing braking deceleration through the energy recovery torque.
The regenerative braking capacity of the motor can be understood as the maximum torque which can be provided by the motor in the reverse rotation mode, the vehicle control unit compares the braking recovery torque and the sliding recovery torque which are sent by the intelligent brake, the large execution mode is adopted, the braking and the speed reduction are realized through the energy recovery torque, namely the braking and the speed reduction are realized through the motor, and the braking and the speed reduction are not realized through mechanical hydraulic pressure.
And S312, when the braking request is larger than the regenerative braking capacity of the motor, setting the torque limit value of the whole vehicle controller to be zero, building pressure by the intelligent braking system according to a calibration result of the mechanical hydraulic pressure, and performing braking and speed reduction through the mechanical hydraulic pressure.
When the braking request is larger than the regenerative braking capability, the mechanical hydraulic braking generates friction force to provide braking for the whole vehicle, when the whole vehicle controller responds to the torque recovery request of the intelligent braking system, the whole vehicle controller generally feeds back the current recovery capability limit value to the intelligent braking system, the whole vehicle controller calculates the energy recovery torque limit value according to the states of the battery, the motor and the whole vehicle, when the energy recovery is not met (for example, the battery is in a full-power state and cannot be charged continuously), the torque limit value is set to be 0, the energy recovery torque value output by the intelligent braking system cannot exceed the torque limit value sent by the whole vehicle controller, and at the moment, the speed can be reduced only through the mechanical hydraulic pressure of the intelligent braking system. The brake deceleration is achieved by the superposition of energy recovery torque and mechanical hydraulic pressure.
In an embodiment of the method for controlling the braking end deceleration of the electric vehicle of the present invention, the step S31 may further include:
and step S313, when the vehicle is about to stop, reducing the energy recovery torque or reducing the hydraulic braking force through the terminal deceleration control system.
Wherein the terminal deceleration control system is triggered by a physical key or by a function switch arranged on an instrument panel or a vehicle-mounted entertainment information system, wherein the vehicle-mounted entertainment information system can be MP5 vehicle-mounted multimedia. The following describes the reduction of the energy recovery torque by the tip end deceleration control system and the reduction of the hydraulic braking force by the tip end deceleration control system, respectively.
In the case where the energy recovery torque is reduced by the terminal deceleration control system, the step S313 may specifically include:
step S3131, when the driver brakes, if the current energy recovery torque can satisfy the deceleration required by the brake pedal stroke, the intelligent braking system does not push its internal mechanism to generate mechanical hydraulic pressure, and performs braking deceleration through the energy recovery torque.
As an example and not by way of limitation, the preset speed threshold is 8 km/h. When a driver brakes, the vehicle generates deceleration according to the pedal travel acquired by the pedal displacement sensor, and when the current energy recovery torque can meet the deceleration required by the current brake pedal travel, the intelligent brake system cannot push the internal mechanism to generate mechanical hydraulic pressure.
And step S3132, when the vehicle speed is less than the preset speed threshold value, the intelligent braking system reduces the energy recovery torque in a gradient manner according to the current deceleration and the brake pedal travel of the whole vehicle.
As an example and not by way of limitation, the energy recovery torque decline gradient is 200Nm/s, when a driver brakes, and the vehicle is about to stop, for example, the vehicle speed is less than 8km/h, the intelligent braking system reduces the energy recovery torque in a gradient manner according to the current deceleration of the whole vehicle and in combination with the travel of the brake pedal, and due to the reduction of the energy recovery torque, the deceleration generated by the whole vehicle is correspondingly reduced, so that the longitudinal shock and the shock of the vehicle are reduced, and the braking comfort is improved.
In the case where the hydraulic braking force is reduced by the terminal deceleration control system, the step S313 may specifically include:
step S3131', when the driver is braking, if the current energy recovery torque does not satisfy the deceleration required for the brake pedal stroke, the mechanical hydraulic pressure generated by the energy recovery torque and the internal mechanism-driving hydraulic pressure of the smart brake system performs braking deceleration.
When the current energy recovery torque can not meet the deceleration required by the current brake pedal stroke, the deceleration of the whole brake is generated by the energy recovery torque and the mechanical hydraulic pressure generated by pushing hydraulic pressure by the internal mechanism of the intelligent brake system.
And step S3132', when the vehicle speed is smaller than the preset speed threshold value, the intelligent braking system retreats partial stroke according to the current deceleration and the brake pedal stroke of the whole vehicle, and mechanical hydraulic pressure generated by hydraulic braking is reduced.
When a driver brakes and the vehicle is about to stop, for example, the vehicle speed is less than 8km/h, the intelligent brake system retreats partial stroke by an internal mechanism according to the current deceleration of the whole vehicle and combining the stroke of a brake pedal, reduces the pressure generated by hydraulic braking, reduces the pressure of a wheel cylinder, and retreats a rack to release pressure on the premise that the intelligent brake system judges that the vehicle is safe, and retreats to the previous pressure after the vehicle is stably stopped. Due to the reduction of the hydraulic braking pressure, the deceleration generated by the whole vehicle is correspondingly reduced, so that the longitudinal vibration and jerk of the vehicle are reduced, the problem of violent pitching before and after the vehicle stops is solved, and the braking comfort is improved. In this case, the pedal travel is not changed since the current intelligent braking system is decoupled.
And step S32, if the energy recovery torque request state bit is invalid, the actual braking recovery torque output by the vehicle controller is zero, the intelligent braking system builds pressure according to the calibration result of the mechanical hydraulic pressure, and braking deceleration is carried out through the mechanical hydraulic pressure.
And judging whether the energy recovery torque request state bit is effective or not through an intelligent braking system. In the event of a battery pack or motor failure, the energy recovery torque request status bit is invalid. At the moment, the intelligent brake system builds pressure to realize the target deceleration corresponding to the travel of the brake pedal. For example, in the case where the energy recovery torque request state bit is normal, the brake pedal stroke corresponds to a deceleration of 0.3g, in which the deceleration of the energy recovery torque contribution is 0.1g and the deceleration of the mechanical hydraulic pressure contribution is 0.2 g; when the energy recovery torque request status bit is invalid, the energy recovery torque is 0, at the moment, the mechanical hydraulic pressure is made larger, the deceleration of the energy recovery torque contribution is complemented by the mechanical hydraulic pressure, the deceleration of the mechanical hydraulic pressure contribution is changed from 0.2g to 0.3g, for a driver, the driver can generate the deceleration of the vehicle according to the pedal stroke acquired by the pedal displacement sensor when braking, and the deceleration generated by the same brake pedal stroke is the same regardless of whether the energy recovery torque request status bit is normal or invalid, and only some adjustment is made on internal distribution (namely the energy recovery torque and the mechanical hydraulic pressure).
It should be noted that the end deceleration control system of the electric vehicle is not triggered under some special conditions, for example, when a driver is in emergency braking (deceleration is greater than 0.4g), or when a safety function of the entire vehicle such as ABS (anti-lock braking system) \ TCS (traction control system) \ VDC (power storage battery) is triggered, or when the system is out of order, the function is not triggered, so as to ensure the safety performance of the entire vehicle.
Therefore, the energy recovery is realized through the interaction between the intelligent brake system (EBS) and the Vehicle Control Unit (VCU), and the brake discomfort caused by the whole vehicle shock and pause when a driver is about to stop is reduced. It should be noted that, in some embodiments, the deceleration control at the end of braking of the electric vehicle may be implemented by interaction between a Vehicle Control Unit (VCU) and an electronic stability system (ESC), or interaction between an intelligent braking system and the electronic stability system (ESC), which is not specifically limited by the invention.
According to the control method for the deceleration of the brake tail end of the electric automobile, provided by the embodiment of the invention, the brake deceleration is controlled through the energy recovery torque and the mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the obtained brake pedal stroke, so that the mild deceleration and the stable brake stop of the automobile are realized, the problem of brake comfort can be improved to the greatest extent, and the discomfort brought by the fact that the whole automobile bends forward and bends backward during the brake stop is avoided.
Thus, various embodiments of the present disclosure have been described in detail. Some details that are well known in the art have not been described in order to avoid obscuring the concepts of the present disclosure. Those skilled in the art can now fully appreciate how to implement the teachings disclosed herein, in view of the foregoing description.
Although some specific embodiments of the present disclosure have been described in detail by way of example, it should be understood by those skilled in the art that the foregoing examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. It will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.
Claims (6)
1. A method for controlling the deceleration of the brake tail end of an electric automobile is characterized by comprising the following steps:
in a decoupling state, calibrating the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal;
when braking, obtaining the travel of a brake pedal;
controlling braking deceleration through energy recovery torque and/or mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the acquired stroke of the brake pedal, wherein,
in the decoupling state, the method for calibrating the change relation of the mechanical hydraulic pressure along with the travel of the brake pedal specifically comprises the following steps:
detecting the travel of a brake pedal when a driver steps on the brake pedal by an intelligent brake system and by using a displacement sensor arranged on the brake pedal;
when the energy recovery torque is zero, detecting mechanical hydraulic pressure generated in the intelligent brake system when a driver steps on a brake pedal through the intelligent brake system by using a hydraulic sensor;
according to the detected stroke of the brake pedal and the corresponding mechanical hydraulic pressure, the change relation of the mechanical hydraulic pressure along with the stroke of the brake pedal is calibrated to obtain an MAP table,
the obtaining of the stroke of the brake pedal specifically comprises:
the travel of the driver for stepping on the brake pedal is obtained by an intelligent brake system and a displacement sensor arranged on the brake pedal,
the method for controlling the braking deceleration through the energy recovery torque and/or the mechanical hydraulic pressure according to the calibration result of the mechanical hydraulic pressure and the obtained travel of the brake pedal specifically comprises the following steps:
if the energy recovery torque request state is normal, responding to an energy recovery torque request sent by an intelligent braking system, and outputting an actual braking recovery torque by the vehicle control unit;
and if the energy recovery torque request state bit is invalid, the actual braking recovery torque output by the vehicle controller is zero, the intelligent braking system builds pressure according to the calibration result of the mechanical hydraulic pressure, and the braking speed is reduced through the mechanical hydraulic pressure.
2. The method for controlling deceleration at the braking end of an electric vehicle according to claim 1, wherein if the energy recovery torque request status bit is normal, the vehicle controller outputs the actual braking recovery torque in response to an energy recovery torque request from the intelligent braking system, and specifically comprises:
when the braking request is smaller than the regenerative braking capacity of the motor, the vehicle control unit compares the braking recovery torque and the sliding recovery torque which can be output by the intelligent braking system, takes a larger value as the actual braking recovery torque, and performs braking deceleration through the energy recovery torque;
when the braking request is larger than the regenerative braking capacity of the motor, the whole vehicle controller sets the torque limit value to be zero, and at the moment, the intelligent braking system builds pressure according to the calibration result of the mechanical hydraulic pressure and performs braking and speed reduction through the mechanical hydraulic pressure.
3. The method for controlling deceleration at the braking end of an electric vehicle according to claim 2, wherein if the energy recovery torque request status bit is normal, the vehicle control unit outputs the actual braking recovery torque in response to an energy recovery torque request from the smart braking system, further comprising:
when the vehicle is about to stop, the energy recovery torque is reduced or the hydraulic braking force is reduced by the terminal deceleration control system.
4. The method for controlling the deceleration at the braking tail end of the electric automobile according to claim 3, characterized in that the tail end deceleration control system is triggered by a physical key or a functional switch arranged on an instrument panel or a vehicle-mounted entertainment information system.
5. The method for controlling the braking terminal deceleration of the electric vehicle according to claim 3, wherein the reducing the energy recovery torque or the reducing the hydraulic braking force by the terminal deceleration control system when the vehicle is about to stop includes:
when a driver brakes, if the current energy recovery torque can meet the deceleration required by the travel of a brake pedal, the intelligent brake system does not push the internal mechanism to generate mechanical hydraulic pressure, and the intelligent brake system brakes and decelerates through the energy recovery torque;
when the vehicle speed is smaller than the preset speed threshold value, the intelligent braking system reduces the energy recovery torque in a gradient manner according to the current deceleration and the brake pedal travel of the whole vehicle.
6. The method for controlling the braking terminal deceleration of the electric vehicle according to claim 3, wherein the reducing the energy recovery torque or the reducing the hydraulic braking force by the terminal deceleration control system when the vehicle is about to stop includes:
when a driver brakes, if the current energy recovery torque does not meet the deceleration required by the travel of a brake pedal, the mechanical hydraulic pressure generated by pushing hydraulic pressure through the energy recovery torque and an internal mechanism of the intelligent brake system is used for braking and decelerating;
when the speed of the vehicle is smaller than the preset speed threshold value, the intelligent braking system retreats partial stroke of an internal mechanism of the intelligent braking system according to the current deceleration and the stroke of a brake pedal of the whole vehicle, and mechanical hydraulic pressure generated by hydraulic braking is reduced.
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| CN114274931B (en) * | 2022-03-03 | 2022-06-17 | 万向钱潮股份有限公司 | Pressure target decision method for multi-axis commercial vehicle brake-by-wire system |
| CN114643962B (en) * | 2022-03-31 | 2023-03-14 | 上汽通用五菱汽车股份有限公司 | Vehicle brake control method and device and computer equipment |
| CN115891943A (en) * | 2022-11-22 | 2023-04-04 | 中国第一汽车股份有限公司 | Brake pedal control method and system and vehicle with same |
| CN115933618B (en) * | 2023-01-05 | 2023-11-24 | 江苏永久摩托车科技有限公司 | Intelligent driving fault monitoring system and method based on Internet of vehicles |
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| KR102417509B1 (en) * | 2016-11-22 | 2022-07-05 | 현대자동차주식회사 | Method for controlling regenerative brake cooperation system |
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