CN115384320A - Electric automobile braking energy recovery device and recovery method - Google Patents
Electric automobile braking energy recovery device and recovery method Download PDFInfo
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- CN115384320A CN115384320A CN202211203748.2A CN202211203748A CN115384320A CN 115384320 A CN115384320 A CN 115384320A CN 202211203748 A CN202211203748 A CN 202211203748A CN 115384320 A CN115384320 A CN 115384320A
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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
- B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
- B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
- B60L15/2009—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed for braking
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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
- 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
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/40—Drive Train control parameters
- B60L2240/42—Drive Train control parameters related to electric machines
- B60L2240/423—Torque
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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
- B60L2240/00—Control parameters of input or output; Target parameters
- B60L2240/60—Navigation input
- B60L2240/64—Road conditions
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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
- B60L2260/00—Operating Modes
- B60L2260/40—Control modes
- B60L2260/44—Control modes by parameter estimation
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Regulating Braking Force (AREA)
Abstract
The invention relates to the technical field of automobile braking energy recovery, in particular to an electric automobile braking energy recovery device and a recovery method, wherein a primary section simulator comprises a shell, a connecting frame, a limiting sleeve, a guide sleeve, a spring I, a spring II and a spring III; one side of the shell is provided with a sealing cover for connection, one end of the shell is connected with a vacuum booster, and the connecting frame is used for being hinged with a brake pedal of the electric automobile; stop collar sets up in the inside one side of casing, and spring III sets up at the stop collar inboardly, and III one sides of spring contact with the uide bushing, and bellying and II contacts of spring on the uide bushing outside, inboard and I contact of spring, spring I, spring II and III's spring rate crescent, spring III is less than valve spring's spring rate in the vacuum booster. The invention properly increases the electric braking force of the driving motor to ensure the required braking force, effectively reduces the intervention times and the intervention pressure value of the hydraulic braking, and effectively increases the energy recovery of the vehicle.
Description
Technical Field
The invention relates to the technical field of automobile braking energy recovery, in particular to a braking energy recovery device and a braking energy recovery method for an electric automobile.
Background
With the development of new energy automobiles, the requirements of consumers on the cruising ability of automobiles are higher and higher, the comprehensive cruising mileage of the automobiles is limited by the current technology of vehicle batteries, and the energy density of the batteries cannot be greatly improved. In order to increase the endurance mileage of the vehicle, the control of the recovery of the braking energy of the new energy automobile becomes important.
In the related technology, the existing braking energy recovery strategies of the electric automobile are in series connection and parallel connection, a series system needs to use an electric power assisting device which can be decoupled, and can effectively coordinate electric braking and hydraulic braking, however, the single-piece cost of the series system of the electric automobile is higher, the single-piece cost floats upwards, a parallel system directly overlaps electric braking on the basis of the hydraulic braking, the traditional braking energy recovery strategy of the parallel system is that a driver loosens a braking pedal, a driving motor adjusts recovery torque according to the change of the speed of the automobile, for example, a patent with the application number of CN201811610381.X discloses a parallel braking energy recovery control method of a pure electric automobile, which is applied to controlling the output feedback torque of the motor of the pure electric automobile and controlling the output torque of an electric retarder, and comprises the current braking state of the pure electric automobile is determined when the operation parameters of the pure electric automobile meet the predefined energy recovery conditions; obtaining feedback torque according to the current braking state; outputting feedback torque; and outputting the target torque by the eddy current retarder when the operation parameter does not meet the predefined energy recovery condition.
Traditional parallel system hydraulic braking superposes at once with electric brake for the vehicle slows down, and hydraulic braking's intervention when this kind of mode vehicle initial stage slows down causes the loss of vehicle kinetic energy, consequently electric brake power superimposed volume reduces relatively, leads to can't carrying out the braking energy recovery of maximize under the non-emergency braking operating mode, causes the energy waste, and hydraulic braking frequently intervenes the life who influences the brake lining simultaneously.
Disclosure of Invention
In view of this, the present invention provides a braking energy recovery apparatus and a braking energy recovery method for an electric vehicle, so as to solve the problem that the maximum braking energy recovery cannot be performed under the non-emergency braking condition in the existing energy recovery manner.
Based on the above purpose, the invention provides a braking energy recovery device of an electric vehicle, which comprises a vacuum booster, a braking switch, a vehicle control unit and a driving motor, and is characterized by further comprising a first-stage simulator,
the brake switch is electrically connected with the vehicle control unit, and is arranged on a brake pedal of the electric vehicle when in use;
the initial section simulator comprises a shell, a connecting frame, a limiting sleeve, a guide sleeve, a spring I, a spring II and a spring III;
one side of the shell is provided with a sealing cover for connection, one end of the shell is connected with the vacuum booster, and the connecting frame is used for being hinged with a brake pedal of the electric automobile;
the connecting frame comprises a connecting rod, a push plate and a U-shaped frame, the connecting rod, the push plate and the U-shaped frame are fixedly connected, and the connecting rod is rotatably connected with the sealing cover;
the limiting sleeve is arranged on one side inside the shell, the spring III is arranged on the inner side of the limiting sleeve, one side of the spring III is in contact with the guide sleeve, a convex part on the outer side of the guide sleeve is in contact with the spring II, the inner side of the guide sleeve is in contact with the spring I, the spring stiffness of the spring I, the spring II and the spring III is gradually increased, and the spring III is smaller than the spring stiffness of a valve spring in the vacuum booster;
during normal braking, when the initial-stage simulator enables the brake pedal to not overcome the spring force of the valve spring and the vacuum booster push rod return spring in the process of stepping on a certain initial-stage stroke, at the moment, the vacuum booster is not pressed, and the vehicle control unit ensures the required braking force by increasing the electric braking force of the driving motor.
Optionally, the vehicle control unit is electrically connected with an ABS controller, the vehicle control unit monitors the motor torque T in real time, and the ABS controller reads the wheel speed Va and the vehicle speed V in real time and calculates the wheel slip ratio λ according to parameters;
and calculating the current road surface adhesion coefficient u according to the wheel speed slip lambda and the motor torque T, and when the road surface adhesion coefficient u is lower than a preset adhesion coefficient, controlling the electric braking force of the driving motor to gradually reduce by the vehicle controller until the vehicle exits.
Optionally, the guide sleeve is connected with a damper through a clamp spring on the inner side, the end parts of the spring I and the damper are in contact with a limiting groove on the push plate, and the damper is used for enabling the brake pedal to have damping feeling.
Optionally, the guide sleeve is provided with a sound absorbing ring on the inner side, and the sound absorbing ring is used for absorbing noise generated in the compression and recovery processes of the spring.
Based on the same invention creation, the invention also provides a recovery method of the electric automobile braking energy recovery device, which comprises the following steps:
s101: detecting a brake switch signal, brake pipeline pressure, a vehicle deceleration rate change rate and a vehicle speed signal, and identifying the driving intention of a driver;
s102: and adjusting a braking energy recovery characteristic curve according to the judgment of each parameter result in the S101.
Optionally, the S101 includes: and when the road adhesion coefficient is lower than a preset adhesion coefficient, the vehicle control unit controls the electric braking force of the driving motor to be gradually reduced until the vehicle exits.
Optionally, the identifying the driving intention of the driver comprises: when a driver steps on a brake pedal, no matter whether the vacuum booster acts or not, the brake switch signal is sent to the vehicle control unit, and after the brake switch signal is triggered, the ABS controller monitors the pressure of a brake pipeline in real time through a built-in pressure estimation model;
generating a current period deceleration alpha when vehicle braking starts, and calculating a current deceleration change rate delta a by the vehicle controller 8 according to the vehicle deceleration a:
wherein, the parameter alpha is the current period deceleration, and alpha' is the lower period deceleration;
the method includes the steps that a maximum threshold value of a current deceleration degree change rate delta alpha is preset, when delta alpha reaches the maximum threshold value, the current braking intention of a driver is emergency braking, and when delta alpha is smaller than the maximum threshold value, the current braking intention of the driver is non-emergency braking intention.
Optionally, the motor torque T is monitored in real time through the vehicle control unit, the ABS controller reads the wheel speed Va and the vehicle speed V in real time, and the wheel slip ratio λ is calculated according to the parameters;
and calculating the current road adhesion coefficient u according to the actual wheel speed slip lambda and the motor torque T.
Optionally, the S102 includes:
s201: the vehicle control unit calculates the current road surface adhesion coefficient of the vehicle;
s202: according to the current road adhesion coefficient, the vehicle controller judges whether the road surface has a low adhesion coefficient, if so, step 208 is executed; otherwise, the system executes step S203;
s203: the vehicle control unit judges whether a brake switch signal exists or not, if so, S205 is executed; otherwise, executing S204;
s204: executing a traditional brake motor recovery characteristic curve;
s205: the ABS controller judges whether the brake pipeline pressure is generated, if so, the step S207 is executed; otherwise, executing S206;
s206: executing a recovery characteristic curve of the brake motor under the non-emergency braking working condition of the additionally installed initial section simulator;
s207: the vehicle control unit judges whether the change rate of the braking deceleration degree reaches a preset threshold value, if so, step S208 is executed, otherwise, step S206 is executed;
s208: zero braking energy recovery;
s209: the flow ends.
Optionally, the S102 includes:
s301: according to the current road surface adhesion coefficient, the vehicle control unit judges whether the road surface has a low adhesion coefficient, if so, the step S302 is executed; otherwise, the system executes step S303;
s302: zero braking energy recovery;
s303: the vehicle control unit judges whether a brake switch signal exists or not, and if so, S11 is executed; otherwise, S305 is executed;
s304: when the vehicle control unit judges that the change rate of the braking deceleration degree is smaller than a preset threshold value, adjusting the electric braking torque value of the driving motor according to the vehicle speed signal, and if the vehicle speed V is larger than V2, switching the system to a low braking energy recovery curve; if the vehicle speed V1 is less than V and less than V2, the system is switched to a medium braking energy recovery curve at the moment; if the vehicle speed V is less than V1, the system is switched to a high braking energy recovery curve;
s305: the conventional brake motor recovery characteristic curve is executed.
When the driver normally brakes, because the spring rate of spring I913, spring II 905 and spring III 904 is gradually increased, spring III 904 is less than the spring rate of valve spring 404 in the vacuum booster 4, and initial section simulator 9 makes brake pedal 2 not overcome the spring force of valve spring 404, booster push rod 402 return spring in stepping on certain initial section stroke in-process, and vacuum booster 4 does not build pressure this moment, but detects brake switch 3's switching signal after, and the demand braking force is ensured through the electric brake force that suitably increases driving motor to the system, has ensured the deceleration of brake pedal 2 sensation and vehicle demand, and the effectual intervention number of times and the intervention pressure value that reduces hydraulic braking simultaneously, the effectual vehicle energy recovery that has increased.
Drawings
In order to more clearly illustrate the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a schematic structural diagram of a recycling apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a first stage simulator according to an embodiment of the present invention;
FIG. 3 is an enlarged view taken at A in FIG. 2;
FIG. 4 is a view of the push plate of FIG. 2 in the direction B;
FIG. 5 is a flow chart of a recovery method according to an embodiment of the present invention;
FIG. 6 is a flow chart of adjusting a recovery characteristic according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a braking energy recovery curve according to an embodiment of the present invention.
Labeled as: 2. a brake pedal; 3. a brake switch; 4. a vacuum booster; 5. a master cylinder; 6. a vacuum pump; 7. an ABS controller; 8. a vehicle control unit; 401. a diaphragm plate of the air chamber; 402. a booster push rod; 403. a vacuum valve; 404. a valve spring; 405. a return spring; 9. a first stage simulator; 901. a housing; 910. a connecting frame; 907. locking the screw; 909. a gasket; 906. a sealing cover, 9010 and a connecting rod; 9011. pushing a plate; 9012. a U-shaped frame; 911. a bearing; 908. a shock-absorbing ring; 902. a limiting sleeve; 903. a guide sleeve; 904. a spring III; 905. a spring II; 914. a clamp spring; 915. a damper; 912. a sound absorbing ring; 913. a spring I; 9013. a limiting groove; 90110. a semicircular groove.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to specific embodiments below.
It is to be noted that technical terms or scientific terms used herein should have the ordinary meaning as understood by those having ordinary skill in the art to which the present invention belongs, unless otherwise defined. The use of "first," "second," and similar terms in the present application do not denote any order, quantity, or importance, but rather the terms are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that the element or item listed before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", 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.
As shown in fig. 1 to 4, a braking energy recovery device for an electric vehicle comprises a vacuum booster 4, a braking switch 3, a vehicle control unit 8 and a driving motor, and is characterized by further comprising a first-stage simulator 9, wherein,
the brake switch 3 is electrically connected with the vehicle control unit 8, and the brake switch 3 is arranged on a brake pedal 2 of the electric vehicle when in use;
the primary simulator 9 comprises a shell 901, a connecting frame 910, a limiting sleeve 902, a guide sleeve 903, a spring I913, a spring II 905 and a spring III 904;
one side of the shell 901 is provided with a sealing cover 906 for connection, optionally, one side of the shell 901 is connected with the sealing cover 906 through a plurality of locking screws 907 and sealing gaskets 909 in the circumferential direction, one end of the shell 901 is connected with the vacuum booster 4, optionally, the shell 901 is connected with a booster push rod 402 through a pin shaft, and the connecting frame 910 is used for being hinged with a brake pedal 2 of an electric automobile;
the connecting frame 910 comprises a connecting rod 9010, a push plate 9011 and a U-shaped frame 9012, the connecting rod 9010, the push plate 9011 and the U-shaped frame 9012 are fixedly connected, the connecting rod 9010 is rotatably connected with a sealing cover 906, optionally, the connecting rod 9010 is rotatably connected with a bearing 911 arranged on the sealing cover 906 and the sealing cover 906, and a damping ring 908 is arranged on the inner side of the sealing cover 906, so that a good buffering effect can be achieved, and abnormal sound is avoided;
the limiting sleeve 902 is arranged on one side inside the shell 901, the spring III 904 is arranged on the inner side of the limiting sleeve 902, one side of the spring III 904 is in contact with the guide sleeve 903, a convex part on the outer side of the guide sleeve 903 is in contact with the spring II 905, the inner side of the guide sleeve 903 is in contact with the spring I913, the spring stiffness of the spring I913, the spring II 905 and the spring III 904 is gradually increased, and the spring III 904 is smaller than that of the valve spring 404 in the vacuum booster 4;
one end of the vacuum booster 4 is connected with a vacuum pump 6 through a vacuum hose, and the brake master cylinder 5 is connected with an ABS controller 7 through a brake pipeline;
during normal braking, when the initial stage simulator 9 enables the brake pedal 2 not to overcome the spring force of the valve spring 404 and the booster push rod return spring 405 in the process of stepping down a certain initial stage stroke, the vacuum booster 4 is not pressurized, and the vehicle control unit 8 ensures the required braking force by increasing the electric braking force of the driving motor.
When the driver normally brakes, because the spring rate of spring I913, spring II 905 and spring III 904 is gradually increased, spring III 904 is less than the spring rate of valve spring 404 in the vacuum booster 4, and initial section simulator 9 makes brake pedal 2 not overcome the spring force of valve spring 404, booster push rod 402 return spring in stepping on certain initial section stroke in-process, and vacuum booster 4 does not build pressure this moment, but detects brake switch 3's switching signal after, and the demand braking force is ensured through the electric brake force that suitably increases driving motor to the system, has ensured the deceleration of brake pedal 2 sensation and vehicle demand, and the effectual intervention number of times and the intervention pressure value that reduces hydraulic braking simultaneously, the effectual vehicle energy recovery that has increased.
The vacuum booster 4 further includes a plenum diaphragm 401, a booster push rod 402, and a vacuum valve 403.
In some embodiments, the vehicle control unit 8 is electrically connected with the ABS controller 7, the vehicle control unit 8 monitors the motor torque T in real time, the ABS controller 7 reads the wheel speed Va and the vehicle speed V in real time, and calculates the wheel slip ratio λ according to parameters;
calculating a current road surface adhesion coefficient u according to the wheel speed slip λ and the motor torque T, and calculating the current road surface adhesion coefficient u according to the wheel speed slip λ and the motor torque T is the prior art, and details are not repeated herein, and when the road surface adhesion coefficient u is lower than a preset adhesion coefficient, the vehicle controller 8 controls the electric braking force of the driving motor to gradually decrease until exiting.
The road adhesion coefficient is determined as one of determination conditions for triggering the braking energy recovery function. When the vehicle belongs to the ice and snow road surface, the road surface adhesion coefficient is lower than the preset adhesion coefficient, and in order to drive safety and driving comfort, the vehicle controller 8 controls the electric braking force of the driving motor to be gradually reduced until quitting, so that the phenomenon that the ABS controller 7 is frequently triggered due to the fact that the hydraulic braking force and the electric braking force are superposed to aggravate vehicle locking is effectively avoided.
In some embodiments, the inner side of the guide sleeve 903 is connected with a damper 915 through a clamp spring 914, and the ends of the spring i 913 and the damper 915 are in contact with a limiting groove 9013 on the push plate 9011, wherein the damper 915 can enable the brake pedal 2 to feel more damped, and avoid puckery.
In some embodiments, a sound absorbing ring 912 is disposed inside the guide sleeve 903, wherein the sound absorbing ring 912 can effectively absorb noise generated during the compression and recovery of the spring.
In some embodiments, the push plate 9011 is provided with a plurality of semicircular grooves 90110 in the outer circumferential direction, so that materials can be effectively reduced, and the cost can be reduced.
As shown in fig. 5, in order to further implement the present invention, the present invention further provides a method for recovering braking energy of an electric vehicle, including:
s101: detecting a signal of a brake switch 3, the pressure of a brake pipeline, the change rate of the deceleration of the vehicle and a vehicle speed signal, and identifying the driving intention of a driver;
s102: and adjusting a braking energy recovery characteristic curve according to the judgment of each parameter result in the S101.
According to different parameter results, the energy recovery characteristic curve matched with the parameter results is adjusted, and the energy recovery effect of the automobile is improved. The specific numerical value of the braking energy recovery characteristic curve is set by a person skilled in the art according to the whole vehicle and the actual situation of the vehicle, and is not limited specifically here.
In some embodiments, said S101 comprises before: and detecting the actual wheel speed, the vehicle speed and the motor torque of the pure electric vehicle, calculating the current road adhesion coefficient of the road where the vehicle is located, and when the road adhesion coefficient is lower than the preset adhesion coefficient, controlling the electric braking force of the driving motor to be gradually reduced by the vehicle control unit 8 until the vehicle exits. It should be noted that the preset adhesion coefficient is set by a person skilled in the art according to practical situations, and is not limited herein.
The road adhesion coefficient is determined as one of determination conditions for triggering the braking energy recovery function. When the vehicle belongs to the ice and snow road surface, the road surface adhesion coefficient is lower than the preset adhesion coefficient, in order to ensure the driving safety and the driving comfort, the vehicle control unit 8 controls the electric braking force of the driving motor to gradually reduce until quitting, so that the phenomenon that the ABS controller 7 is frequently triggered due to the fact that the hydraulic braking force and the electric braking force are superposed to aggravate the locking of the vehicle is effectively avoided, and the driving safety of the vehicle is improved.
In some embodiments, the identifying the driving intent of the driver comprises: when a driver steps on the brake pedal 2, no matter whether the vacuum booster 4 acts or not, a signal of the brake switch 3 is sent to the vehicle control unit 8, and after the signal of the brake switch 3 is triggered, the ABS controller 7 monitors the pressure of a brake pipeline in real time through a built-in pressure estimation model;
generating a current period deceleration alpha when vehicle braking starts, and calculating, by the vehicle controller 88, a current deceleration degree change rate Δ alpha according to the vehicle deceleration alpha:
wherein, the parameter a is the current period deceleration, and a' is the lower period deceleration.
The method includes the steps that a maximum threshold of a current deceleration degree change rate delta alpha is preset, when the delta alpha reaches the maximum threshold, a current braking intention of a driver is emergency braking, and when the delta alpha is smaller than the maximum threshold, the driver is a non-emergency braking intention.
When the delta a reaches the maximum threshold value, the current braking intention of the driver is emergency braking, and the braking energy is not recovered. It should be noted that the maximum threshold value of the deceleration rate change rate is set by a person skilled in the art according to actual situations, and is not limited to the specific example.
In some embodiments, the vehicle control unit 8 monitors the motor torque T in real time, and the ABS controller 7 reads the wheel speed Va and the vehicle speed V in real time to calculate the wheel slip ratio λ according to the parameters.
And calculating the current road adhesion coefficient u according to the actual wheel speed slip lambda and the motor torque T.
As shown in fig. 6, in some embodiments, the S102 includes:
s201: the vehicle control unit 8 calculates the current road surface adhesion coefficient of the vehicle;
s202: according to the current road surface adhesion coefficient, the vehicle control unit 8 judges whether the road surface has a low adhesion coefficient, if so, step 208 is executed; otherwise, the system executes step S203;
s203: the vehicle control unit 8 judges whether a signal of the brake switch 3 exists, if so, S205 is executed; otherwise, executing S204;
s204: executing a traditional brake motor recovery characteristic curve;
s205: the ABS controller 7 judges whether the brake line pressure is generated, if yes, step S207 is executed; otherwise, executing S206;
s206: executing a recovery characteristic curve of the brake motor under the non-emergency braking working condition of the additionally-installed initial-stage simulator 9;
s207: the vehicle control unit 8 judges whether the change rate of the braking deceleration degree reaches a preset threshold value, if so, step S208 is executed, otherwise, step S206 is executed;
s208: zero braking energy recovery;
s209: the flow ends.
By the method, the energy recovery characteristic curve matched with the parameter result is adjusted according to different parameter results, and the energy recovery effect of the automobile is improved.
As shown in fig. 7, in some embodiments, the S102 includes:
s301: according to the current road adhesion coefficient, the vehicle control unit 8 judges whether the road surface has a low adhesion coefficient, and if so, the step S302 is executed; otherwise, the system executes step S303;
s302: zero braking energy recovery;
s303: the vehicle control unit 8 judges whether a signal of the brake switch 3 exists or not, and if yes, S11 is executed; otherwise, S305 is executed;
s304: when the vehicle controller 8 judges that the change rate of the braking deceleration degree is smaller than a preset threshold value, adjusting the electric braking torque value of the driving motor according to the vehicle speed signal, and if the vehicle speed V is larger than V2, switching the system to a low braking energy recovery curve; if the vehicle speed V1 is more than V and less than V2, the system is switched to a medium braking energy recovery curve; if the vehicle speed V is less than V1, the system is switched to a high braking energy recovery curve;
s305: the conventional brake motor recovery characteristic curve is executed.
The low braking energy recovery curve is a bc section braking energy recovery curve in a graph 1, the middle braking energy recovery curve is an ab section braking energy recovery curve in the graph 1, and the high braking energy recovery curve is an oa section braking energy recovery curve in the graph 1.
The electric braking torque value changes along with the speed, the electric braking torque value increases along with the speed increase in the low-speed section, the electric braking torque value slowly decreases along with the speed increase in the medium-speed section, and the electric braking torque value decreases along with the speed increase in the high-speed section in an accelerating manner.
Those of ordinary skill in the art will understand that: the discussion of any embodiment above is meant to be exemplary only, and is not intended to intimate that the scope of the disclosure, including the claims, is limited to these examples; within the idea of the invention, also features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.
The present invention is intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalents, improvements, and the like that may be made without departing from the spirit or scope of the present invention are intended to be included within the scope of the present invention.
Claims (10)
1. A braking energy recovery device of an electric automobile comprises a vacuum booster, a braking switch, a vehicle control unit and a driving motor, and is characterized by also comprising an initial stage simulator,
the brake switch is electrically connected with the vehicle control unit, and is arranged on a brake pedal of the electric vehicle when in use;
the initial section simulator comprises a shell, a connecting frame, a limiting sleeve, a guide sleeve, a spring I, a spring II and a spring III;
one side of the shell is provided with a sealing cover for connection, one end of the shell is connected with the vacuum booster, and the connecting frame is used for being hinged with a brake pedal of the electric automobile;
the connecting frame comprises a connecting rod, a push plate and a U-shaped frame, the connecting rod, the push plate and the U-shaped frame are fixedly connected, and the connecting rod is rotatably connected with the sealing cover;
the limiting sleeve is arranged on one side in the shell, the spring III is arranged on the inner side of the limiting sleeve, one side of the spring III is in contact with the guide sleeve, a convex part on the outer side of the guide sleeve is in contact with the spring II, the inner side of the guide sleeve is in contact with the spring I, the spring stiffness of the spring I, the spring II and the spring III is gradually increased, and the spring III is smaller than the spring stiffness of a valve spring in the vacuum booster;
during normal braking, when the initial segment simulator makes the brake pedal not overcome in certain initial segment stroke process of stepping on valve spring with vacuum booster push rod return spring's spring force, this moment vacuum booster does not build pressure, vehicle control unit is through increasing the demand braking force is ensured to driving motor's electric brake force.
2. The braking energy recovery device of the electric vehicle according to claim 1, wherein the vehicle control unit is electrically connected with an ABS controller, the vehicle control unit monitors the motor torque T in real time, the ABS controller reads the wheel speed Va and the vehicle speed V in real time, and calculates the wheel slip ratio λ according to parameters;
and calculating a current road surface adhesion coefficient u according to the wheel speed slip lambda and the motor torque T, and when the road surface adhesion coefficient u is lower than a preset adhesion coefficient, controlling the electric braking force of the driving motor to be gradually reduced by the vehicle control unit until the vehicle control unit exits.
3. The electric automobile braking energy recovery device of claim 1, wherein the inner side of the guide sleeve is connected with a damper through a snap spring, the spring I and the end of the damper are in contact with a limiting groove on the push plate, and the damper is used for enabling the brake pedal to have damping feeling.
4. The braking energy recovery device for the electric vehicle of claim 1, wherein a sound absorption ring is disposed inside the guide sleeve, and the sound absorption ring is configured to absorb noise generated during compression and recovery of the spring.
5. The method for recovering the braking energy recovery device of the electric vehicle as claimed in claim 2, characterized by comprising the following steps:
s101: detecting a brake switch signal, brake pipeline pressure, a vehicle deceleration rate change rate and a vehicle speed signal, and identifying the driving intention of a driver;
s102: and adjusting a braking energy recovery characteristic curve according to the judgment of each parameter result in the S101.
6. The method for recovering the braking energy of the electric vehicle according to claim 5, wherein the step S101 is preceded by: and when the road adhesion coefficient is lower than a preset adhesion coefficient, the vehicle control unit controls the electric braking force of the driving motor to be gradually reduced until the vehicle exits.
7. The method for recovering the braking energy of the electric automobile according to claim 6, wherein the recognizing the driving intention of the driver comprises: when a driver steps on a brake pedal, no matter whether the vacuum booster acts or not, the brake switch signal is sent to the vehicle control unit, and after the brake switch signal is triggered, the ABS controller monitors the pressure of a brake pipeline in real time through a built-in pressure estimation model;
generating a current period deceleration alpha when vehicle braking starts, and calculating a current deceleration change rate delta a by the vehicle controller 8 according to the vehicle deceleration a:
wherein, the parameter alpha is the current period deceleration, and alpha' is the lower period deceleration;
the method includes the steps that a maximum threshold of a current deceleration degree change rate delta alpha is preset, when the delta alpha reaches the maximum threshold, a current braking intention of a driver is emergency braking, and when the delta alpha is smaller than the maximum threshold, the driver is a non-emergency braking intention.
8. The recovery method of the braking energy recovery device of the electric vehicle according to claim 6, wherein the vehicle control unit monitors the motor torque T in real time, the ABS controller reads the wheel speed Va and the vehicle speed V in real time, and calculates the wheel slip ratio λ according to the parameters;
and calculating the current road adhesion coefficient u according to the actual wheel speed slip lambda and the motor torque T.
9. The method for recovering the braking energy of the electric vehicle according to claim 7, wherein the step S102 includes:
s201: the vehicle control unit calculates the current road adhesion coefficient of the vehicle;
s202: according to the current road surface adhesion coefficient, the vehicle control unit judges whether the road surface has a low adhesion coefficient, if so, step 208 is executed; otherwise, the system executes step S203;
s203: the vehicle control unit judges whether a brake switch signal exists or not, if so, S205 is executed; otherwise, executing S204;
s204: executing a traditional brake motor recovery characteristic curve;
s205: the ABS controller judges whether the brake pipeline pressure is generated, if so, the step S207 is executed; otherwise, executing S206;
s206: executing a recovery characteristic curve of the brake motor under the non-emergency braking working condition of the additionally-installed initial-stage simulator;
s207: the vehicle control unit judges whether the change rate of the braking deceleration degree reaches a preset threshold value, if so, the step S208 is executed, otherwise, the step S206 is executed;
s208: zero braking energy recovery;
s209: the flow ends.
10. The method for recovering the braking energy of the electric vehicle according to claim 7, wherein the step S102 includes:
s301: according to the current road surface adhesion coefficient, the vehicle control unit judges whether the road surface has a low adhesion coefficient, if so, the step S302 is executed; otherwise, the system executes step S303;
s302: zero braking energy recovery;
s303: the vehicle control unit judges whether a brake switch signal exists or not, and if so, S11 is executed; otherwise, S305 is executed;
s304: when the vehicle control unit judges that the change rate of the braking deceleration degree is smaller than a preset threshold value, adjusting the electric braking torque value of the driving motor according to the vehicle speed signal, and if the vehicle speed V is larger than V2, switching the system to a low braking energy recovery curve; if the vehicle speed V1 is less than V and less than V2, the system is switched to a medium braking energy recovery curve at the moment; if the vehicle speed V is less than V1, the system is switched to a high braking energy recovery curve;
s305: the conventional brake motor recovery characteristic curve is executed.
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