CN102322491A - Execution device for automobile electronic mechanical brake system - Google Patents

Abstract

The invention relates to an actuator for an automobile electromechanical braking system, which is used to solve the technical problem of complex structures of the existing automobile electromechanical braking actuators. The technical solution is that the rotor shaft (7-1) of the motor (7) is coaxial with the auxiliary screw (5) of the roller screw, and is tightly connected by the connecting part (6) with the key (6-3); the key (6 -3) Cooperate with the circumferential positioning of the rotor shaft (7-1) and the auxiliary screw of the roller screw (5), and the retaining ring (6-1) aligns the rotor shaft (7-1) and the auxiliary screw of the roller screw The rod (5) is axially positioned, the roller screw auxiliary screw (5) and the roller screw auxiliary nut (3) are evenly distributed with several rollers (4), and the threads of the roller screw auxiliary screw (5) Both the teeth and the secondary nut of the roller screw (3) are engaged with the roller (4); the brake caliper block (2) is fastened together with the secondary nut of the roller screw (3). Since the permanent magnet brushless DC servo motor is used, the planetary roller screw is used in the execution part, the gear reduction mechanism is omitted, and the structure of the execution device is simpler.

Description

Automotive Electromechanical Brake System Actuator

technical field

The invention relates to a brake system actuator, in particular to an automobile electromechanical brake system actuator.

Background technique

In order to improve the active safety performance of automobiles, researches on replacing traditional hydraulic braking systems with electromechanical braking (EMB) systems have been extensively carried out in recent years. Existing EMBs generally use DC brushless servo control motors or switched reluctance motors as the drive device, through the gear reduction mechanism to achieve the function of deceleration and torque increase, and finally the actuator implements friction braking.

There are two types of common actuators, namely wedge mechanism and ball screw pair. The wedge mechanism is generally integrated with the larger driven gear, and the wedge rotates with the gear and produces axial displacement to push the brake caliper block to achieve braking. The EMB using the ball screw pair as the brake actuator generally connects the screw with the output gear, and the screw nut is integrated with the brake caliper block, and finally converts the rotation of the screw into the axial movement of the nut and the pad.

Refer to Figure 9. The document "Development and Pressure Estimation of Automobile Electromechanical Brake Actuator [J] Yang Kun et al. Automobile Technology 2008.10P24-27" discloses an automotive electromechanical brake actuator, which includes a motor , planetary reduction mechanism and ball screw three parts. Wherein the motor rotor 9 is made into a hollow type, and a ball screw sub-nut 8 is nested inside it to ensure the axial movement of the ball screw sub-nut 8 , and the left end of the ball screw sub-nut 8 fixes the brake caliper block 2 . The right end of the motor rotor 9 is fixedly connected with the sun gear 15 of the planetary gear train, and the two parts rotate together; the right end of the motor stator 10 is fixedly connected with the ring gear 11 of the planetary gear train. The planetary gear 12 is installed inside the sun gear 15 and the ring gear 11 and is kept in revolution by the planetary carrier 13 . The ball screw auxiliary screw 14 is integrated with the planet carrier 13 and rotates with it.

When the braking system is working, the motor rotor 9 and the sun gear 15 rotate together, and the torque is output by the cage 13 after decelerating and increasing torque through the planetary gear system. The cage 13 rotates together with the ball screw sub screw 14, and the ball screw sub nut 8 converts the rotational motion of the ball screw sub screw 14 into the linear motion of the ball screw sub nut 8 and pushes the brake caliper block 2 to press Tighten the brake disc 1 to achieve braking.

When the brake is released, the motor rotor 9 and the sun gear 15 rotate in the opposite direction together, and the torque is output by the cage 13 after decelerating and increasing the torque through the planetary gear system. The cage 13 rotates together with the ball screw sub screw 14, and the ball screw converts the rotational motion of the ball screw sub screw 14 into the linear motion of the ball screw sub nut 8 and drives the brake caliper block 2 to loosen the braking force. The compression of disc 1 releases the brake.

The motor rotor 9 disclosed in the literature is hollow, and a ball screw auxiliary nut 8 is nested inside, and a planetary gear reduction mechanism is used to realize deceleration and torque increase. Wherein the sun gear 15 of the planetary gear system will be fixed with the motor rotor 9, the ring gear 11 of the planetary gear system will be fixed with the motor stator 10, and the cage 13 of the planetary gear system will be fixed with the leading screw 14 of the ball screw pair. The mechanical structure of the system is complex due to the consideration of the connection between the various parts of the planetary gear train and the motor, lead screw and other components.

Contents of the invention

In order to overcome the shortcomings of the complex structure of the existing automotive electromechanical braking actuator, the invention provides an automotive electromechanical braking system actuator. The device is driven by a brushless DC motor, and the planetary roller screw is used for the execution part. Since the gear reduction mechanism is omitted, the structure of the execution device can be simplified.

The technical solution adopted by the present invention to solve the technical problem is: an actuator for an automotive electromechanical braking system, comprising a brake disc 1, a brake caliper block 2 and a motor 7, and the brake caliper block 2 encloses the brake disc 1 , which is characterized in that it also includes a roller screw auxiliary nut 3, a roller 4, a roller screw auxiliary screw 5 and a connecting part 6. The rotor shaft 7-1 of the motor 7 is coaxial with the auxiliary screw 5 of the roller screw, and is tightly connected by the matching key 6-3 of the connecting part 6. The connecting sleeve 6-2 cooperates with the key 6-3, the rotor shaft 7-1 and the auxiliary screw 5 of the roller screw are positioned circumferentially, and the spring retaining ring 6-1 is aligned with the rotor shaft 7-1 and the auxiliary screw of the roller screw. The screw 5 carries out axial positioning, the auxiliary screw 5 of the roller screw and the auxiliary nut 3 of the roller screw are evenly distributed with several rollers 4, the thread teeth of the auxiliary screw 5 of the roller screw and the auxiliary nut of the roller screw 3 are all engaged with roller 4. The brake caliper block 2 is fastened together with the auxiliary nut 3 of the roller screw.

The motor 7 is a permanent magnet brushless DC servo control motor.

The roller screw auxiliary screw 5 and the roller screw auxiliary nut 3 have the same direction of rotation, the same pitch, and the same lead as the helix, the roller screw auxiliary nut 3 is an internal thread, and the roller screw auxiliary nut 3 is an internal thread. Bar 5 is external thread.

The outside of the roller 4 has a single thread thread, and its pitch is consistent with the pitch of the auxiliary screw 5 of the roller screw and the auxiliary nut 3 of the roller screw.

The connecting part 6 includes a spring retaining ring 6-1, a connecting sleeve 6-2, a key 6-3, and a set screw 6-4; the connecting sleeve 6-2 is a cylindrical structure, and its axial direction has a Key 6-3 matching pass-through keyway. The key 6-3 has a threaded hole, and the set screw 6-4 passes through the threaded hole to fix the key 6-3 in the keyway of the shaft end of the butt joint between the rotor shaft 7-1 and the auxiliary screw 5 of the roller screw, There is an annular groove at the butt joint between the rotor shaft 7-1 and the auxiliary lead screw 5 of the roller screw and the initial position of the connecting sleeve 6-2, which is used for installing the retaining ring 6-1.

The beneficial effects of the present invention are: due to the use of the permanent magnet brushless DC servo control motor, the planetary roller screw is used for the execution part, the gear reduction mechanism is omitted, and the structure of the execution device is simpler.

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a cross-sectional view of an actuator for an automotive electromechanical braking system according to the present invention.

Fig. 2 is an enlarged cross-sectional view of the connection part in Fig. 1 .

Fig. 3 is an enlarged axial view of the connecting sleeve in Fig. 2 .

Fig. 4 is an enlarged axonometric view of the auxiliary nut of the roller screw in Fig. 1 .

Fig. 5 is an enlarged axonometric view of the assembled roller screw nut and brake caliper block in Fig. 1 .

Fig. 6 is an enlarged view of the structure of the roller screw pair in Fig. 1 .

Figure 7 is a force diagram of a single wheel during braking.

Figure 8 is a force diagram of the brake disc and brake caliper during braking.

Fig. 9 is a cross-sectional view of an actuator of an automotive electromechanical braking system in the background art.

In the figure, 1-brake disc; 2-brake caliper block; 3-roller screw nut; 4-roller; 5-roller screw screw; 6-connecting parts; 6-1-spring Retaining ring; 6-2-connecting sleeve; 6-3-key; 6-4-set screw; 7-motor; 7-1-motor shaft; 8-ball screw nut; 9-motor rotor; 10 -Motor stator; 11-ring gear; 12-planetary gear; 13-cage; 14-ball screw auxiliary screw; 15-sun gear; V is the driving direction of the car; F _xb is the ground braking force; W is the wheel Vertical load; Tp is the thrust of the axle to the wheel; Fz is the normal support force of the ground to the wheel; F is the positive pressure of the brake caliper block on the brake disc; r is the rolling radius of the wheel.

Detailed ways

In this embodiment, the above-mentioned Santana 2000 model takes the one-sided front wheel as an example to carry out the design calculation, and its parameters are shown in Table 1 below:

Table.1 Main parameter list

project Vehicle Curb Quality tire model Brake disc outer diameter Working radius R parameters 1140kg 185/70 R13 86T 256mm 106mm

Assume that the load on the front axle is 60% when the vehicle is stationary, and the load on the left and right wheels is the same. When braking, the force on the wheel is shown in Figure 2. Fxb is the ground braking force, W is the vertical load of the wheel, Tp is the thrust of the axle to the wheel, Fz is the normal support force of the ground to the wheel, and F is the normal pressure of the friction lining on the brake disc, all in N . r is the rolling radius of the wheel, and R is the effective working radius of the brake disc, in mm.

为0.9。则路面最大制动力：Considering the impact of the forward shift of the axle load during braking, the normal force of the front wheel will increase by 50% compared with that at rest. Therefore Fz can be calculated. Assuming that the braking process is on a dry asphalt or concrete road, and the tire slip rate is 15%-20%, then the peak adhesion coefficient of the road

is 0.9. Then the maximum braking force on the road surface is:

Since two brake caliper blocks clamp the brake disc during braking, in order to give full play to the effectiveness of the brake module, the braking force on the brake disc must be greater than the ground braking force. Right now:

2FμR≥F _xb r (2)

F is the positive pressure of the brake pad, μ is the friction coefficient of the brake, take 0.4, R is the working radius of the brake disc, and r is the rolling radius of the wheel.

Calculated by formula (1), the maximum braking force on the ground is 4617N. It can be calculated from Table 1 that the tire rolling radius r is 294.48mm. Bring relevant data into formula (2) to calculate F≥16000N

1) Selection of roller screw.

The roller screw has the advantages of high transmission efficiency, high precision, good synchronization and long service life. Therefore, the ball screw pair is used in this braking module to convert the rotational motion of the motor into the linear motion of the nut.

The known data are as follows:

The maximum axial working load is F=16000N, the material is GCr15, HRC=60-62. Consider the maximum axial working load as the maximum dynamic load C, and look up the table to select the model of the roller screw used as RV20X2.

When the EMB is working, the torque of the auxiliary screw of the roller screw should be according to the formula:

$\mathrm{<span\; class="notranslate">\; T</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; pF</span>}}{\mathrm{<span\; class="notranslate">\; 2000</span>}\mathrm{<span\; class="notranslate">\; \&pi;\&eta;</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

calculate. Substitute screw pitch p=2mm, screw efficiency pair efficiency η=0.82, nut axial working load F=16000N into the above formula to get T=6.214Nm.

2) Selection of motor.

The electronic mechanical braking system requires the motor to have the characteristics of high frequency response and low inertia. And it can meet the maximum braking torque requirement, so the permanent magnet brushless DC servo control motor is preferred.

Motor power should meet:

$\mathrm{<span\; class="notranslate">\; P</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Tn</span>}}{\mathrm{<span\; class="notranslate">\; 9550</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 4</span>}<span\; class="notranslate">\; )</span>$

Among them, T=6.214Nm, and n is the rated speed of the motor, which is set to 2000r/m. Substituting the power of the motor into the above formula is 1.3kw.

Refer to Figures 1-8. The executive device of the automobile electromechanical braking system of the present invention includes a brake disc 1 , a brake caliper block 2 , a roller screw nut 3 , a roller 4 , a roller screw auxiliary screw 5 , a connecting part 6 and a motor 7 . The brake caliper block 2 encloses the brake disc 1, and the rotor shaft 7-1 of the motor 7 is coaxial with the auxiliary screw 5 of the roller screw, and is tightly connected by the connecting part 6 and the key 6-3. The connecting sleeve 6-2 cooperates with the key 6-3, the rotor shaft 7-1 and the auxiliary screw 5 of the roller screw are positioned circumferentially, and the spring retaining ring 6-1 is aligned with the rotor shaft 7-1 and the auxiliary screw of the roller screw. The screw 5 carries out axial positioning, the auxiliary screw 5 of the roller screw and the auxiliary nut 3 of the roller screw are evenly distributed with several rollers 4, the thread teeth of the auxiliary screw 5 of the roller screw and the auxiliary nut of the roller screw 3 are all engaged with roller 4. The brake caliper block 2 is fastened together with the auxiliary nut 3 of the roller screw.

The rotor shaft 7-1 of the motor 7 is coaxial with the auxiliary screw 5 of the roller screw, and the shaft end of the butt joint between the rotor shaft 7-1 and the auxiliary screw 5 of the roller screw has a semicircular keyway, and the bottom of the keyway has a fixed keyway. key threaded hole. Keyway inboard car has the annular groove that snap ring 6-1 is installed, and snap ring 6-1 is a standard part, and connecting sleeve 6-2 substrate is cylindrical structure, and mills out a through shape keyway in it.

The connecting part 6 includes a spring retaining ring 6-1, a connecting sleeve 6-2, a key 6-3, and a set screw 6-4; the connecting sleeve 6-2 is a cylindrical structure with a key 6 -3 matching pass-through keyways. The key 6-3 has a threaded hole, and the set screw 6-4 passes through the threaded hole to fix the key 6-3 in the keyway of the shaft end of the butt joint between the rotor shaft 7-1 and the auxiliary screw 5 of the roller screw, There is an annular groove at the butt joint between the rotor shaft 7-1 and the auxiliary lead screw 5 of the roller screw and the initial position of the connecting sleeve 6-2, which is used for installing the retaining ring 6-1.

When installing, first insert the connecting sleeve 6-2 into the left side of the roller screw auxiliary screw 5 shaft, then align the roller screw auxiliary screw 5 with the rotor shaft 7-1 of the motor and put it into the A-type key, and respectively screw in the setscrews 6-4 at both ends of the keyway. After the connecting sleeve 6-2 is installed, place the two retaining rings 6-1 in the annular grooves on the rotor shaft 7-1 of the motor and the auxiliary screw 5 of the roller screw respectively. Like this, the key 6-3 and the connecting sleeve 6-2 have played the circumferential positioning between the rotor shaft 7-1 of the motor and the auxiliary screw 5 of the roller screw, ensuring that the motor shaft 7-1 and the roller screw The synchronous operation of the auxiliary leading screw 5 of the rod. Simultaneously, the retaining rings 6-1 on both sides of the connecting sleeve 6-2 play an axial positioning and prevent the connecting sleeve 6-2 from slipping in the axial direction.

The outer diameters of the brake caliper block 2 and the auxiliary nut 3 of the roller screw are both circular. The circumference of the brake caliper block 2 is evenly distributed with four countersunk holes for installing hexagon socket head cap screws. And on the left side of the auxiliary nut 3 of the roller screw, there are four threaded holes. During installation, align the holes on the brake caliper block 2 and the secondary nut 3 of the roller screw and screw in the hexagon socket head cap screw, so that the brake caliper block 2 and the secondary nut 3 of the roller screw are fastened as one. Therefore, the brake caliper block 2 can move axially together with the auxiliary nut 3 of the roller screw.

The roller screw pair adopts the formed product of the screw manufacturer. The auxiliary screw 5 of the roller screw and the auxiliary nut 3 of the roller screw contain helixes with the same direction of rotation, the same pitch, and the same lead. The difference is that the auxiliary nut 3 of the roller screw is an internal thread, while the auxiliary screw 5 of the roller screw is an external thread. 5-13 circular rollers 4 with different numbers are evenly distributed on the roller screw auxiliary screw 5 and the roller screw auxiliary nut 3. There are single-line thread teeth on the outside of the roller 4, and the pitch of the roller screw is the same as that of the roller screw. The screw pitches of the auxiliary lead screw 5 and the auxiliary nut 3 of the roller screw are consistent.

When working, the auxiliary screw 5 of the roller screw rotates as the active part. Since the thread teeth of the auxiliary screw 5 of the roller screw mesh with the roller 4, the roller 4 is driven around the auxiliary screw of the roller screw. 5 revolutions and rotations, similar to the planetary gears in the planetary gear train. When the roller 4 moves, it also drives the auxiliary nut 3 of the roller screw to generate axial displacement. Finally, the auxiliary nut 3 of the roller screw drives the brake caliper block 2 at its left end to realize braking and release of braking together.

Electromechanical brake system actuator work flow:

During braking, the control motor 7 drives the auxiliary screw 5 of the roller screw to rotate together, the auxiliary screw 5 of the roller screw meshes with the thread teeth of the roller 4, and drives the roller 4 to rotate and revolve. During the movement, the roller 4 drives the secondary nut 3 of the roller screw to generate an axial displacement to the left. Since the roller screw nut 3 is integrated with the brake caliper block 2, the brake caliper block 2 moves to the left together with the roller screw nut 3 and exerts positive pressure on the brake disc 1 to realize the braking function of the system .

When the brake is released, the control motor 7 drives the auxiliary screw 5 of the roller screw to rotate in reverse together, the auxiliary screw 5 of the roller screw meshes with the thread teeth of the roller 4, and drives the roller 4 to generate rotation and revolution. During the movement, the roller 4 drives the secondary nut 3 of the roller screw to generate an axial displacement to the left. Since the roller screw nut 3 is integrated with the brake caliper block 2, the brake caliper block 2 moves to the left together with the roller screw nut 3 and exerts positive pressure on the brake disc 1 to realize the braking function of the system .

In this embodiment, the original motor-reduction mechanism-executing mechanism is changed into a motor-executing mechanism structure, and the reduction mechanism is no longer used.

Claims (5)

1. vehicle electromechanical braking system actuating device; Comprise brake disc (1), brake calipers piece (2) and motor (7); Brake calipers piece (2) double team brake disc (1) is characterized in that: also comprise roller screw pair nut (3), roller (4), roller screw pair leading screw (5) and connected element (6); The rotor shaft (7-1) of said motor (7) is coaxial with roller screw pair leading screw (5), and is fastenedly connected by connected element (6) fit key (6-3); Coupling sleeve (6-2) cooperates with key (6-3); Rotor shaft (7-1) is circumferentially located with roller screw pair leading screw (5); Check ring (6-1) carries out axially locating to rotor shaft (7-1) and roller screw pair leading screw (5); Roller screw pair leading screw (5) is uniformly distributed with several rollers (4) with roller screw pair nut (3), and the worm tooth of roller screw pair leading screw (5) and roller screw pair nut (3) all are meshed with roller (4); Brake calipers piece (2) fastens as one with roller screw pair nut (3).

2. vehicle electromechanical braking system actuating device according to claim 1 is characterized in that: said motor (7) is a DC permanent-magnetic brushless servocontrol motor.

3. vehicle electromechanical braking system actuating device according to claim 1; It is characterized in that: said roller screw pair leading screw (5) has identical rotation direction with roller screw pair nut (3); The helix of identical pitch, identical helical pitch; Roller screw pair nut (3) is an internal thread, and roller screw pair leading screw (5) is an outside thread.

4. vehicle electromechanical braking system actuating device according to claim 1 is characterized in that: there is the worm tooth of single line the outside of said roller (4), and its pitch is consistent with the pitch of roller screw pair leading screw (5) and roller screw pair nut (3).

5. vehicle electromechanical braking system actuating device according to claim 1 is characterized in that: said connected element (6) comprises check ring (6-1), coupling sleeve (6-2), key (6-3), Cock screw (6-4); Said coupling sleeve (6-2) is a tubular construction, and it axially has the logical shape keyway with key (6-3) coupling; Said key (6-3) is threaded the hole; Cock screw (6-4) passes in the keyway of docking part axle head that tapped hole is fixed in key (6-3) rotor shaft (7-1) and roller screw pair leading screw (5); There is circular groove the docking part of rotor shaft (7-1) and roller screw pair leading screw (5) and coupling sleeve (6-2) initial position corresponding part, are used for mounting spring back-up ring (6-1).

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