CN210000309U

CN210000309U - Brake pedal mechanism with arc groove

Info

Publication number: CN210000309U
Application number: CN201920940884.7U
Authority: CN
Inventors: 田国英; 陈昭翔; 丁宗恒; 唐梧桐; 陈飞; 孙树磊; 邓鹏毅
Original assignee: Xihua University
Current assignee: Xihua University
Priority date: 2019-06-21
Filing date: 2019-06-21
Publication date: 2020-01-31
Anticipated expiration: 2029-06-21

Abstract

The utility model relates to a brake pedal mechanism with arc groove, through arc grooves through parameter optimization at brake pedal tip design, electric push rod and arc groove contact provide suitable stroke for the automobile pedal through this arc groove, make the car obtain reliable brake force, through theoretical analysis and mathematical modeling, acquire optimum arc groove design size, this kind of design method of the optimum arc groove of brake pedal tip can make electric push rod drive motion round pin axle and arc groove reliably contact, provide steady brake force.

Description

Brake pedal mechanism with arc groove

Technical Field

The utility model relates to an automatic driving equips technical field, in particular to kinds of brake pedal mechanism that have the arc groove and the determination method of optimum arc groove parameter.

Background

As the related technology of modifying the traditional vehicle to realize automatic driving is more and more mature, the automatic driving is possible by adding a proper device on the premise of not changing the structure of the traditional vehicle, a stable and reliable braking system is which is an important link for realizing the automatic driving of the vehicle, if the design is not reasonable, the proper braking effect cannot be achieved in , the brake is out of control, in addition, the mechanical structure design and arrangement are easy to interfere in , and the realization of the automatic braking function generally changes the brake pedal driven by manpower into controllable electric drive or hydraulic drive.

At present, most manufacturers adopt an electric driving mode, the mechanical structure of the electric driving type brake pedal is mainly in a motor-push rod mode, or an electric push rod is directly adopted to push the brake pedal, the end of the push rod is hinged with the rod body position of the brake pedal during pushing, the pedal is driven to rotate around the pivot of the push rod during linear action of the push rod, and when the linear stroke of the push rod is converted into the rotation angle of the pedal, an optimization algorithm for performing special treatment on two related strokes is not provided in the prior art, so that the rotation angle of the pedal is always in nonlinear correspondence during the action of the push rod, the nonlinear braking force applied by the brake pedal is caused, the size of the braking force is unstable during different pedal opening degrees, the braking slip phenomenon is easy to occur, and the ideal braking effect.

For example, in the brake pedal feel control method and the simulation device described in the conventional patent CN201710537714X, the simulation device includes a motor, a gear shift mechanism and a push rod, and only a few points of force are given for the relationship between the stroke of the push rod and the pedal stroke, including an initial position, a 50% pedal stroke and a 100% pedal stroke, and such correspondence results in unknown corresponding relationship of the intermediate position, unknown pedal force output by the brake pedal, and unable to meet the actual application requirements.

In the brake pedal force simulation device in the prior patent CN201010189418.3, an air cylinder with a control element is arranged on a frame, a piston rod of the air cylinder is connected with a connecting head through threads, a synchronizing plate extending to the side is fixedly connected to the connecting head, a pressure sensor is arranged at the front end of the connecting head, a front-end roller of the pressure sensor abuts against the brake pedal fixedly arranged on the frame according to the direction of stepping on the brake pedal, a pop-up type displacement sensor is arranged on the side of the air cylinder in parallel with the piston rod, and a contact of the pop-up type displacement sensor abuts against the synchronizing plate.

The electric cylinder brake device and the control method in the prior patent CN 201510245914.9, the electric cylinder brake device in the device controls the push rod of the electric cylinder to retract into the electric cylinder body under the drive of the brake signal, drives the sliding push rod mechanism to apply the brake force to the brake pedal to implement the brake, the automatic control system pushes the brake pedal to a position in the brake stroke to stay or push the brake pedal to the maximum brake stroke position according to the requirement of the brake intensity, when the brake is required to be relieved, the electric cylinder brake device controls the push rod of the electric cylinder to extend out of the electric cylinder body under the drive of the brake signal relief of the automatic control system, drives the sliding push rod mechanism to relieve the brake force to the brake pedal, and the brake pedal returns to the initial state.

Disclosure of Invention

To the above problem, the utility model provides a brake pedal mechanism with circular arc groove to guarantee that brake pedal power output is steady, guarantee reliable braking in succession under the condition of realizing different brake pedal aperture.

In order to realize the purpose of the utility model, the technical scheme adopted by the utility model is that brake pedal mechanism with arc groove, including brake pedal, brake pedal head sets up the end plate and contacts with driver's sole, brake pedal middle part sets up the fulcrum shaft hole that transversely link up, the fulcrum round pin axle passes the fulcrum shaft hole, brake pedal rotates around fulcrum round pin axle axis, the fulcrum round pin axle passes bolted connection and installs on the frame, brake pedal afterbody sets up the pinhole that transversely link up, the round pin axle passes the pinhole, the round pin axle passes through bolted connection with brake master cylinder piston push rod, set up arc groove between pinhole and the fulcrum shaft hole, set up on brake pedal's lower bottom surface, the cambered surface of arc groove contacts with the lateral surface of the motion round pin axle of horizontal placement, motion round pin axle and fulcrum round pin axle parallel arrangement, the motion round pin axle is installed in the rod end of the electric push rod.

The invention has the advantages that considering that most actuating mechanisms are motion pin shafts, the contact stress point of the actuating mechanisms and the brake pedal is a tangent point, if the tangent point is excessively deviated in the working process, the thrust output by the electric push rod cannot be kept in the vertical direction, therefore, the transverse deviation of the tangent point is taken as an optimization target in the invention, in the calculation process, initial parameters are changed in a set range, the maximum value of the transverse deviation absolute value of the corresponding motion pin shaft and the pedal contact tangent point in the working process is obtained by every initial parameter combination, and the initial parameter corresponding to the minimum value in the maximum value of each group of transverse deviation absolute values is finally obtained, so that the stable output of the brake pedal force is ensured, and the continuous and reliable braking is ensured under the condition of different brake pedal opening degrees.

Drawings

FIG. 1 is a front view of a prior art electrically actuated brake pedal configuration;

FIG. 2 is a left side view of FIG. 1;

FIG. 3 is a diagram illustrating a relationship between a tangential point lateral offset and a rising height of a motion pin shaft in the prior art;

FIG. 4 is a brake pedal configuration view;

FIG. 5 is a schematic representation of a kinematic coordinate system of the brake pedal mechanism;

FIG. 6 is a state diagram of the lateral offset Δ of the tangent point between the motion pin and the arc groove when the tangent point moves to t;

FIG. 7 shows preferred embodiments of initial coordinate ranges of the motion pin axes;

FIG. 8 is an optimal arc groove size according to the preferred embodiment of FIG. 7;

FIG. 9 shows the difference between the lateral offset of the tangent point and the single elevation of the motion pin(Δ h ═ 1, 0.1, 0.01, 0.001) relationship (x ═ 29, y ═ 10, R)_c＝15)；

Fig. 10 shows the relationship between Δ and the rising height of the moving pin under h cycle (x is 10, y is-1, R)_c＝15)

FIG. 11 is R_cDelta under cycle_maxThe initial parameter of the arc groove is combined and changed (x is 20, y is-1, R)_c＝[20：30])；

FIG. 12 shows Δ at y cycle_maxThe initial parameter combination change relationship with the arc groove (x is 20, y is-1: -10)]，R_c＝[20：30])；

FIG. 13 is Δ at x cycles_maxThe initial parameter combination change relation with the arc groove (x is 20: 30)]，y＝[-1：-10]，R_c＝[20：30])；

FIG. 14 is Δ_maxThe change relation with the initial x coordinate of the circle center of the arc groove (y is-1, R)_c＝10)；

FIG. 15 is Δ_maxThe initial y coordinate of the center of the arc groove is changed (x is 20, R)_c＝10)；

FIG. 16 is Δ_maxRadius R of arc groove_cCoordinate variation relationship (x ═ 20, y ═ 1);

FIG. 17 is a flow chart of a parameter optimization process.

Detailed Description

The brake pedal mechanism with the arc grooves is shown in fig. 4-5, wherein an end plate is arranged at the head of a brake pedal (4) and is in contact with the sole of a driver, a fulcrum shaft hole (5) which is transversely penetrated is formed in the middle of the pedal (4), a fulcrum pin shaft (7) penetrates through the fulcrum shaft hole (5), the pedal (4) rotates around the axis of the fulcrum pin shaft (7), the fulcrum pin shaft (7) is installed on a frame through bolt connection, a pin hole (1) which is transversely penetrated is formed in the tail of the pedal (4), a pin shaft (8) penetrates through the pin hole (1), the pin shaft (8) is connected with a piston push rod of a brake master cylinder through a bolt, arc grooves (3) are formed in the bottom surface of the pedal (4) between the pin hole (1) and the fulcrum shaft hole (5), the arc grooves (3) are in contact with a horizontally placed motion pin shaft (6), the motion pin shaft (6) is installed at the.

According to the installation structure of the brake pedal (4) and the electric push rod (2), the optimal parameters of the brake pedal mechanism are determined by the following steps:

the brake pedal mechanisms with arc grooves comprise a brake pedal (4), wherein the head of the brake pedal (4) is provided with an end plate which is contacted with the sole of a driver, the middle part of the brake pedal (4) is provided with a fulcrum shaft hole (5) which transversely penetrates through the brake pedal, a fulcrum pin shaft (7) penetrates through the fulcrum shaft hole (5), the brake pedal (4) rotates around the axis of the fulcrum pin shaft (7), the fulcrum pin shaft (7) is installed on a frame through bolt connection, the tail part of the brake pedal (4) is provided with a transversely penetrating pin hole (1), a pin shaft (8) penetrates through the pin hole (1), the pin shaft (8) is connected with a piston push rod of a brake master cylinder through a bolt, arc grooves (3) are formed between the pin hole (1) and the fulcrum shaft hole (5) and on the lower bottom surface of the brake pedal (4), the arc surfaces of the arc grooves (3) are contacted with the outer side surface of a horizontally placed motion pin shaft (6), the motion pin shaft (6) is arranged in parallel with the fulcrum pin shaft (7), the motion pin shaft (6;

the method is characterized in that: the brake pedal mechanism with the arc groove comprises the following components:

a. a rectangular coordinate system is established by taking the circle center of the fulcrum shaft hole (5) as the origin (0, 0) of the coordinate system, and the initial coordinate of the circle center of the motion pin shaft (6) is taken as (x)₁₀，y₁₀) Radius R₁(ii) a The initial coordinate of the center of the pin hole (1) is set as (x)₂₀，y₂₀)；(x₁₀，y₁₀)、(x₂₀，y₂₀)、R₁Is a known parameter determined according to the geometry of the brake pedal (4);

setting the initial coordinate (x) of the circle center of the arc groove (3)_c0，y_c0) Radius R_cAll the 3 parameters are unknown parameters;

the initial coordinate of the tangent point of the motion pin shaft (6) and the arc groove (3) is set as (x)_q0，y_q0) The parameter is an indirect calculation parameter;

setting the single-rise height of the electric push rod (2) as delta; the rising height of the electric push rod (2) is h when the electric push rod works to t, and the circle center (x) of the moving pin shaft (6) is at t_1t，y_1t) The circle center (x) of the arc groove (3)_ct，y_ct) The cutting of the motion pin shaft (6) and the arc groove (3)Point coordinates (x)_qt，y_qt) Center coordinates (x) of the pin hole (1)_2t，y_2t)；

Setting the coordinate (x) of the motion pin shaft (6) according to the geometric dimension of the pedal₁₀，y₁₀) Initial variation range: x is the number of₁₀＝x₁₁～x_1n，y₁₀＝y₁₁～y_1n(ii) a Provided with an arc groove (3) with a radius R_cInitial variation range: r_c＝R_c1～R_cn(ii) a The range of the rising height h of the electric push rod (2) is as follows: h is 0 to h_max；

b. Using a cyclic calculation with x₁₀＝x₁₁～x_1nAs the th recycle, i.e., the outermost recycle, and in the th recycle, y₁₀＝y₁₁～y_1nNesting for a second iteration; in the second recirculation with R_c＝R_c1～R_cnNesting for a third iteration; in the third circulation, h is equal to 0-h_maxAs a fourth iteration for the variable; h is the cycle of the variable, which is the innermost cycle in the calculation process; in the fourth iteration the following calculations are made:

① when the electric push rod (2) is at the initial position, according to the geometrical relationship between the arc groove (3) and the moving pin shaft (6):

x_c0＝x₁₀，y_c0＝y₁₀+R₁-R_c(1-1)

according to the geometric relationship between the tangent point and the moving pin shaft (6):

x_q0＝x₁₀，y_q0＝y₁₀+R₁(1-2)

② when the electric push rod (2) moves upwards at the moment t, the electric push rod (2) only moves in the vertical direction, therefore

x_1t＝x₁₀，y_1t＝y₁₀+h

Because the distance between the circle center of the arc groove (3) and the origin of the coordinate is constant all the time, the coordinate (x) of the circle center of the arc groove (3) at the moment t can be known_ct，y_ct) The following formula may be used:

the circular arc groove (3) is always tangent to the moving pin shaft (6), so the circle center (x) of the circular arc groove (3) at the moment t_ct，y_ct) To the center (x) of the moving pin shaft (6)_1t，y_1t) The distance remains constant and can be given by:

(x_ct-x_1t)²+(y_ct-y_1t)²＝(R_c-R₁)²(1-4)

combined vertical type (1-3) and (1-4) solving for circle center coordinate (x) of arc groove (3) at time t_ct，y_ct) (ii) a Based on the coordinate value, according to the geometric characteristics of the tangent point of the arc groove (3) and the motion pin shaft (6), the coordinate (x) of the tangent point of the motion pin shaft (6) and the arc groove (3) at the moment t_qt，y_qt) To the center of two circles (x)_ct，y_ct)、(x_1t，y_1t) The distances are respectively the radius R of each circle_cAnd R₁The following formula may be used:

the joint type (1-5) and (1-6) can solve the tangent point coordinate (x) of the motion pin shaft (6) and the arc groove (3) at the moment t_qt，y_qt) (ii) a Tangent point abscissa x at time t_qtWith the initial position abscissa x_q0Absolute value of difference Δ ═ x_qt-x_q0The transverse offset of the tangent point of the moving pin shaft (6) and the arc groove (3) is represented in the working process;

the circle center coordinate (x) of the arc groove (3)_ct，y_ct) To the initial circle center (x) of the pin hole (1)₂₀，y₂₀) The distance is constant, and the center (x) of the pin hole (1) moves to the moment t_2t，y_2t) The distance to the origin (0, 0) is constant and can be given by:

(x_2t-x_ct)²+(y_2t-y_ct)²＝(x₂₀-x_c0)²+(y₂₀-y_c0)²(1-8)

connecting vertical type (1-7) and (1-8) to solve the circle center coordinate (x) of the pin hole (1) at the time t_2t，y_2t) (ii) a By the longitudinal axis y of the pin hole_2tWith the initial position ordinate y₂₀Difference h between_yRepresenting the rising height of the end part of the pedal in the working process;

h_y＝|y_2t-y₂₀|

c. in the loop where h is variable, times per loop (i.e., x)₁₀，y₁₀，R_cAre all determined, h is changed from 0 to h in steps of Δ h_maxIn the process) times of Δ are calculated, and after the h cycle is ended, the maximum value Δ of all Δ in the cycle is obtained_max；

d. At R_cUnder a variable cycle (i.e. x)₁₀，y₁₀Determination of R_cStep size of 1 from R_c1Change to R_cnIn process) per R_cnC, repeating the step c, and obtaining the delta_maxValues are stored in array PYL 1;

e. at y₁₀Under a variable cycle (i.e. x)₁₀Determination of y₁₀Step size 1 from y₁₁Change to y_1nIn process) every y_1nRepeating the step d, and storing the obtained PYL1 sequence into a rectangular matrix PYL 2;

f. at x₁₀For variable cycle, every x_1nE, repeating the step e, and combining the obtained matrixes PYL2 to form a new rectangular matrix PYL 3;

g. after the quadruple of cycles is completed, all stored deltas are found in PYL3_maxMinimum value of Δ_mThen will be compared with_mInitial coordinates (x) of the corresponding circular arc groove (3)_c0，y_c0) And radius R thereof_cAs an optimum parameter.

Taking a certain type of mass-produced electric automobile pedal as an example, the following calculation is performed:

firstly, the existing brake pedal is calculated, in the prior art, a hole is formed in the brake pedal and an electric push rod, a moving pin shaft penetrates through the hole, so that the electric push rod is connected with the brake pedal, and a three-dimensional model of the structure of the electric push rod is shown in fig. 1-2.

Because the radius of the hole processed on the pedal needs to be slightly larger than the motion pin shaft, all the holes can be considered to be in contact with tangent points with the motion pin shaft in the working process, and the process of calculating the transverse offset of the tangent points in the working process is as follows:

setting the initial coordinate (x) of the center of a circle of the motion pin shaft (6)₁₀，y₁₀) The range is as follows:

x₁₀＝20～30mm y₁₀＝-10～-1mm

the hole-taking radius is equal to the radius of the moving pin shaft (6): r ═ R₁4mm, the electric push rod rises by 0-15 mm. By simulating the working process of the brake pedal in the prior art, a relation curve of the absolute value delta of the transverse offset of the contact point of the motion pin shaft and the hole at the optimal point in the initial range and the lifting height of the motion pin shaft is obtained as shown in fig. 3, and the data is shown in table 1.

Table 1 offset distance Δ ═ x_qt-x_q0I (unit: mm)

h	1	2	3	4	5	6	7
								Δ	0.602	0.529	0.439	0.331	0.206	0.065	0.092
8	9	10	11	12	13	14	15
								0.266	0.455	1.161	0.872	1.098	1.334	1.576	1.823

Then, establish the model with this technical scheme, with prior art's main difference lie in having set up the circular arc groove on the bottom surface of footboard afterbody, the motion round pin axle contacts with the circular arc groove.

Initial coordinate (x) of circle center of motion pin shaft (6)₁₀，y₁₀) In the range of (2) as a rectangular portion in the two-dimensional model of the brake pedal (4) in FIG. 7Respectively displaying, setting the initial coordinate (x) of the circle center of the motion pin shaft (6)₁₀，y₁₀) The range is as follows:

x₁₀＝20～30mm y₁₀＝-10～-1mm

the radius range of the arc groove (3) is as follows:

R_c＝10～30mm

the rising height h of the electric push rod is 0-15 mm;

x is to be₁₀，y₁₀，R_cH was sequentially carried over into to four cycles, and the results are shown in Table 2:

TABLE 2 all Δ s stored by the matrix PYL3_max

According to the above operation result, the related image is drawn as follows:

(1) randomly selecting parameter combination [ initial coordinate (x) of circle center of motion pin shaft (6) ]₁₀，y₁₀) Has a radius of (29, -10) of the circular arc groove_c＝15]And drawing a change relation curve of the transverse offset and the single ascending height of the motion pin shaft (delta h is 1, 0.1, 0.01 and 0.001), and checking the calculation accuracy, wherein the change relation curve is shown in figure 9.

(2) Drawing to four layers of circularly obtained images:

① is based on the initial coordinate of the center of the motion pin (6) (x)₁₀，y₁₀) Is (20-1), and the radius R of the circular arc groove_cAnd (4) drawing the relation between the transverse offset of the tangent point of the h-cycle motion pin shaft (6) and the arc groove (3) and the lifting height of the motion pin shaft as 10 (namely -th group of initial parameter combination), and referring to fig. 10.

② setting the initial coordinate (x) of the circle center of the motion pin (6)₁₀，y₁₀) To (20, -1), plot Δ_maxRadius R of arc groove_cFrom 10 to 30 (i.e. R)_cCycles) relationship, see fig. 11.

③ starting from the center x of the moving pin shaft (6)₁₀Coordinate 20, plot Δ_maxAnd y₁₀The coordinates change from-1 to-10 (i.e., y-cycle) in relation, see fig. 12.

In FIG. 12, 1 to 11 represent the radii R of the arcuate grooves 3_c＝[10：1：30]Initial coordinate (x) of the center of the moving pin (6)₁₀，y₁₀) Is (20, -1); 12 to 22 each represents a radius R of the arc groove (3)_c＝[10：1：30]Initial coordinate (x) of the center of the moving pin (6)₁₀，y₁₀) Is (20, -2); y is₁₀The process from-1 to-10 is analogized.

④ plotting Δ_maxInitial x of the circle center of the moving pin shaft (6)₁₀The coordinates vary from 20 to 30 (i.e., x cycles) in relation, see fig. 13.

In FIG. 13, 1 to 20 represent the radius R of the arc groove (3)_c＝[20：1：30]Initial coordinate (x) of the center of the moving pin (6)₁₀，y₁₀) Is (20, -1); 21 to 40 each represents the radius R of the arc groove (3)_c＝[20：1：30]Initial coordinate (x) of the center of the moving pin (6)₁₀，y₁₀) Is (20, -2); by analogy, the data code number 1-200 represents the initial x coordinate x of the circle center of the motion pin shaft (6)₁₀＝20，y₁₀From-1 to-10; 201-400 represents the initial x coordinate x of the circle center of the motion pin shaft (6)₁₀＝21，y₁₀From-1 to-10; x is the number of₁₀The process goes from 20 to 30 and so on. (by subscript)

(3) Randomly selecting a parameter combination to observe the influence of certain parameter change on the lateral offset of the tangent point:

① initial coordinate y of the center of the moving pin shaft (6)₁₀＝-1，R_c＝10，Δ_maxThe initial x coordinate change relation with the circle center of the motion pin shaft (6) is shown in figure 14.

From FIG. 14, it can be seen that: when the center y10 coordinate of the motion pin (6) is equal to the radius R of the arc groove_c timing, Δ_maxThe coordinate of the center of the circle of the moving pin shaft (6) is increased and reduced along with the increase of the initial x coordinate.

② as the initial x coordinate of the center of the moving pin (6)_c0＝20，R_c＝10，Δ_maxThe initial y coordinate change relation with the circle center of the motion pin shaft (6) is shown in figure 15.

From FIG. 15, it can be seen that: when the circle center x of the moving pin shaft (6)₁₀Coordinate, arc groove radius R_c constant, Δ_maxThe initial y coordinate of the circle center of the motion pin shaft (6) is increased along with the increase of the initial y coordinate.

③ initial coordinate x of the center of the moving pin shaft (6)_c0＝20，y_c0＝-1，Δ_maxRadius R of arc groove_cSee fig. 16 for the variation.

From FIG. 16, it can be seen that: when the circle center x of the moving pin shaft (6)₁₀，y₁₀Coordinate fixed, Δ_maxFollowing the radius R of the arc groove_cThe variation increases and increases.

From Table 2, it can be seen that in the process of the electric push rod (2) rising to the highest point, Delta_maxThe minimum and the rising height of the end pin shaft (8) reaches the initial coordinate (x) of the circle center of the moving pin shaft (6) corresponding to the actual height required when the brake is completely performed₁₀，y₁₀) Is (30-1), and the radius R of the circular arc groove_cThe 3 parameters are the optimal parameters available on the brake pedal, 10.

In the ascending process of the electric push rod (2), according to the obtained optimal arc groove parameter combination (x)₁₀，y₁₀) Is (30-1), and the radius R of the circular arc groove_cThe innermost loop is searched in reverse, to get the corresponding offset distance Δ ═ x_qt-x_q0I and the center (x) of the pin hole (1)₂₀，y₂₀) Rise height hy ═ y_2t-y₂₀See tables 3, 4 below.

Table 3 absolute value of offset distance Δ ═ x_qt-x_q0I (unit: mm)

Watch 4 pinhole centre (x)₂₀，y₂₀) Height of rise h_y＝|y_2t-y₂₀I (unit: mm)

Compared with the second simulation result of the example , the maximum value of the tangential point lateral offset of the brake pedal with the arc groove in the optimized design can be 0.537 in the working process according to the table 3, and the maximum value of the tangential point lateral offset of the brake pedal in the working process according to the scheme provided by the prior art can be 1.823 in the table 1, so that the optimization effect is obvious.

Claims

The brake pedal mechanism with the arc grooves is characterized by comprising a brake pedal (4), an end plate is arranged at the head of the brake pedal (4) and is in contact with the sole of a driver, a fulcrum shaft hole (5) which is transversely penetrated is formed in the middle of the brake pedal (4), a fulcrum pin shaft (7) penetrates through the fulcrum shaft hole (5), the brake pedal (4) rotates around the axis of the fulcrum pin shaft (7), the fulcrum pin shaft (7) is installed on a frame through bolt connection, a pin hole (1) which is transversely penetrated is formed in the tail of the brake pedal (4), the pin shaft (8) penetrates through the pin hole (1), the pin shaft (8) is connected with a piston push rod of a brake master cylinder through a bolt, arc grooves (3) are formed between the pin hole (1) and the fulcrum shaft hole (5) and on the lower bottom surface of the brake pedal (4), the arc surfaces of the arc grooves (3) are in contact with the outer side surface of a horizontally placed motion pin shaft (6), the end of the motion pin shaft (6) is parallel to the fulcrum pin shaft (7), the motion pin shaft (6) is installed on a vertically arranged electric.