CN107461428B - Automobile brake-by-wire and control method - Google Patents

Abstract

The invention relates to an automobile wire-controlled brake and a control method, including a motor, a transmission mechanism, a one-way clutch, a screw rod, a piston, a friction limiting device and the like. The motor drives the outer ring of the one-way clutch to rotate through the transmission mechanism, and the one-way clutch drives the screw to rotate, and the piston and the brake caliper body are respectively driven to move in opposite directions through the threaded transmission mechanism, and the friction is driven by the same force from both sides of the brake disc. The disc is pressed tightly to achieve efficient braking effect. The invention has the advantages of simple structure, reliable operation, high braking efficiency, automatic adjustment of the braking gap, compensation for the influence caused by friction plate wear, simplified design of the control system, and can be used for driving and parking braking.

Description

Automobile brake-by-wire and control method

technical field

The invention relates to the field of brakes, in particular, it can replace the existing floating caliper disc hydraulic brakes, realize friction discs clamping the brake discs from both sides with the same pressure in an electronically controlled manner, and at the same time realize adjustable brake clearances The invention relates to a wire-controlled mechanical brake with adjustable braking strength, in particular to an automobile brake-by-wire brake and a control method thereof.

Background technique

Brake-by-wire technology is a new type of braking technology that has emerged in recent years. It does not rely on mechanical or hydraulic connections between the brake and the brake pedal. The control system receives the information from the sensor to control the motor to work. Stable and reliable brake control. At present, there are mainly two types of electronic hydraulic braking system (EHB) and electromechanical braking system (EMB). The brake-by-wire system is conducive to the optimization of the braking performance of the whole vehicle, and can be easily integrated with other electronic control systems such as ABS, ASR, ESP, etc., so it has a broad development space.

The electronic hydraulic brake system (EHB) is transformed from the traditional hydraulic brake system. The braking process is more rapid and stable, which improves the braking safety and comfort of the car. However, due to the retention of hydraulic components, it does not have complete All the benefits of brake-by-wire systems are often seen as a precursor to electromechanical brakes (EMB).

The electromechanical braking system (EMB) realizes the braking process through the motor-driven mechanical mechanism, which greatly simplifies the structure of the braking system and makes the brake easier to arrange, assemble and overhaul. However, the existing electromechanical braking system often lacks the function of automatic adjustment of the brake gap in the brake part, which causes the problem that the efficiency of the brake actuator changes indeterminately when the external environment changes and the friction lining is worn. Braking efficiency control brings certain difficulties. At the same time, most of the brakes have problems such as relatively complicated structure and large installation size.

Contents of the invention

The purpose of the present invention is to propose a car brake by wire and a control method. The invention has the advantages of simple structure, reliable operation, etc., and can realize the automatic adjustment of the brake gap. By detecting the displacement or rotation angle of the friction plate driving mechanism, the brake clamping force can be converted and obtained, so that the control system can be adjusted accordingly. simplify.

The technical scheme that realizes the object of the present invention is as follows:

A car brake by wire is provided, including a motor, a transmission mechanism, a one-way clutch, a screw rod, a piston, a friction limiting device, a piston positioning device, a brake caliper body, a brake disc, and a friction plate; the screw rod includes a threaded segment and a cylindrical section, the screw rod is supported on the brake caliper body, and there is no relative movement between the screw rod and the brake caliper body in the axial direction; the friction plate has two pieces, Symmetrically arranged on both sides of the brake disc, one is installed on the piston, and the other is installed on the brake caliper body; the piston is installed on the On the body of the brake caliper, the piston positioning device can only reciprocate the piston in the axial direction and cannot rotate; the piston has an internal thread, which is matched with the threaded section of the screw rod; the screw rod The outer surface of the cylindrical section is used as the inner ring of the one-way clutch, and the outer ring of the one-way clutch is fixedly connected with the terminal element of the transmission mechanism; the movement of the terminal element of the transmission mechanism drives the When the outer ring of the one-way clutch rotates and the one-way clutch is combined to drive the screw to rotate, the piston moves, and the brake caliper body and the screw move in the opposite direction to the piston, driving The friction plate presses the brake disc from both sides; the motor is connected to the input element of the transmission mechanism; a part of the friction limiting device is fixedly installed on the brake caliper body , the other part has a relatively large friction force with the outer surface of the piston. When there is a relative displacement between the piston and the brake caliper body, the friction limiting device will Generate elastic potential energy inside;

When braking, the motor drives the outer ring of the one-way clutch to move through the transmission mechanism, and the one-way clutch is combined to drive the screw to rotate, driving the piston and the brake caliper body respectively move in opposite directions, so that the friction plates are pressed against both sides of the brake disc to obtain an efficient and reliable braking effect. At this time, the gap between the piston and the brake caliper body There is a relative displacement, and elastic potential energy is generated in the friction limiting device; when the brake is released, the motor drives the outer ring of the one-way clutch to move backward through the transmission mechanism, and the one-way clutch is separated. , the elastic potential energy inside the friction limiting device causes the piston and the brake caliper to move relative to each other and return to the original position. At this time, the screw rotates to accommodate the piston and the brake caliper. The relative movement of the brake caliper body;

When the friction plate is worn and the thickness becomes thinner, when the brake works, the motor drives the one-way clutch through the transmission mechanism to combine, drives the screw to rotate, and makes the piston Relatively moving with the brake caliper body, the elastic potential energy in the friction limiting device reaches the maximum, and the braking effect is not good due to the thinning of the friction plate. At this time, the motor continues to work, driving the screw rod Continue to rotate to overcome the friction between the outer surface of the piston and the friction limiting device, so that the piston and the brake caliper body continue to move relative to each other, and press the brake disc to obtain a reliable Efficient braking effect; when the brake is released, the elastic potential energy in the friction limiting device acts to make the piston and the brake caliper move relative to each other. At this time, the piston and the The friction limit device is relatively fixed with a new contact position, realizing the automatic adjustment of the brake clearance.

It also includes adopting a recirculating ball structure between the screw rod and the internal thread of the piston to reduce frictional resistance and improve system working efficiency.

It also includes adding a transmission system between the one-way clutch and the screw rod.

It also includes connecting the terminal element of the transmission mechanism to the inner ring of the one-way clutch, the screw rod to the outer ring of the one-way clutch, and when the brake is working, the one-way clutch is engaged, When the brake is released, the one-way clutch is disengaged.

When there is no transmission link with zero inverse efficiency in the transmission mechanism or the transmission system, a locking mechanism is used to realize the parking brake when the motor is powered off, and the locking mechanism adopts an electromagnetic The brake or the electronically controlled mechanical braking device can be disconnected when the power is turned on, and the transmission element in the transmission link can be fixed when the power is cut off, so as to maintain the pressure between the friction plate and the brake disc to realize the parking brake Function; when the transmission link with zero inverse efficiency is set in the transmission mechanism or the transmission system, the locking mechanism can be used to realize parking brake, or the inverse efficiency is zero, and the power and Movement cannot be transferred in reverse, enabling the described parking brake in the event of a power outage to the motor.

A control method for an automobile brake-by-wire, which is characterized in that it includes the following steps: when the brake is working, the motor drives the transmission mechanism to work, the one-way clutch is combined to drive the screw to rotate, and the The piston and the brake caliper body move to make the friction plate press against both sides of the brake disc, the electronic control unit detects the rotation information of the screw, and combines the current of the motor Calculate the brake clamping force; when the friction lining is worn, the electronic control unit controls the rotation of the motor to compensate for the impact caused by the wear.

Description of drawings

Fig. 1 is a front view of Embodiment 1 of an automobile brake-by-wire of the present invention.

Fig. 2 is an A-direction view of Embodiment 1 of an automobile brake-by-wire according to the present invention.

Fig. 3 is a front view of Embodiment 2 of an automobile brake-by-wire of the present invention.

Fig. 4 is a front view of Embodiment 3 of an automobile brake by wire of the present invention.

Notes in the drawings: 1-brake caliper bracket 2-guide pin 3-brake caliper body 4-target plate 5-screw (5A: cylindrical section, 5B: threaded section) 6-worm gear 7-one-way clutch 8- Worm 9-sealing ring 10-guiding flat key 11-piston 12-friction plate 13-brake disc 14-motor 15-sensor 16-cylindrical roller 17-spring 18-clip 19-motor shaft 20-electromagnetic brake 21- Primary driving gear 22-primary driven gear 23-secondary driving gear 24-secondary driven gear 25-electromagnetic coil 26-return spring 27-lock pin 28-tapered roller bearing

Detailed ways

Referring to accompanying drawing 1 and accompanying drawing 2, an embodiment of the present invention is described in detail.

As shown in Figures 1 and 2, an automobile brake-by-wire includes a brake caliper body (3) that can move on a guide pin (2), and the guide pin (2) is fixed on the brake caliper bracket (1) . There is a brake disc (13) in the jaw of the brake caliper body (3), and there are friction discs (12) on both sides of the brake disc (13), one is mounted on the brake caliper body (3), and the other is mounted on the piston (11), the piston (11) is installed on the brake caliper body (3) through the guide flat key (10) and the sealing ring (9), and the guide flat key (10) makes the piston (11) only move along the axial direction , cannot rotate, there is a relatively large friction force between the contact surface of the sealing ring (9) and the piston (11), when the displacement of the piston (11) is within the elastic deformation range of the sealing ring (9), the sealing ring (9) There is no relative movement between the contact surfaces with the piston (11). The screw rod (5) is supported on the brake caliper body (3) through a tapered roller bearing (28). The screw rod (5) includes two sections, one section is a threaded section (5B) and the other section is a cylindrical section (5A). One end of the piston (11) is equipped with a friction plate (12), and the other end has an internal thread to cooperate with the threaded section (5B) of the screw rod (5). The cylindrical section (5A) of the screw (5) is used as the inner ring of the one-way clutch (7), and the outer ring of the one-way clutch (7) is fixedly connected with the worm wheel (6) in the worm gear transmission mechanism, and the worm (8) is connected with the motor (14) output shaft links to each other.

When the brake is working, the motor (14) drives the worm (8) to rotate, and drives the worm gear (6) to rotate at a reduced speed. At this time, the one-way clutch (7) is combined to drive the screw (5) to rotate. Since the piston (11) cannot rotate, the When the one-way clutch (7) is combined to drive the screw (5) to rotate, the piston (11) and the brake caliper body (3) move in the opposite direction, driving the corresponding friction plate (12) to press from both sides with the same force to the brake disc (13) to achieve efficient and reliable braking effect. At this time, the sealing ring (9) undergoes elastic deformation to store elastic potential energy, and there is no relative movement between the contact surfaces of the sealing ring (9) and the piston (11). When the brake is released, the motor (14) drives the worm (8) to rotate in the reverse direction, and the driving worm (6) also rotates in the reverse direction. At this time, the one-way clutch (7) is separated, the screw (5) is in a free state, and the sealing ring (9) The stored elastic potential energy is released, so that the piston (11) and the brake caliper body (3) move relative to each other, driving the screw (5) to reversely rotate under the action of the elastic potential energy in the sealing ring (9), and all components return to the original state Location.

When the friction plate (12) wears out and the thickness becomes thinner, when the brake works, the motor (14) drives the one-way clutch (7) through the worm (8) and the worm wheel (6) to combine, drives the screw (5) to rotate, and pushes the piston (11) and the brake caliper body (3) are relatively moving, and when the elastic deformation of the seal ring (9) reaches the maximum, the braking effect is not good due to the wear of the friction plate (12), and the motor (14) continues to pass through the joint The one-way clutch (7) drives the screw rod (5) to rotate, that is, the piston (11) and the brake caliper body (3) continue to move relative to each other. Therefore, the sealing ring (9) maintains the maximum amount of elastic deformation, and the piston (11) overcomes the The friction between the sealing ring (9) and the sealing ring (9) match with the new contact surface, that is, the displacement of the piston (11) relative to the brake caliper body (3) is greater than the maximum of the sealing ring (9) amount of elastic deformation. When the brake is released, the motor (14) drives the worm gear mechanism to reverse, the one-way clutch (7) is separated, and the elastic potential energy of the sealing ring (9) is released, so that the piston (11) and the brake caliper body (3) move relatively, Drive the screw (5) to rotate. At this time, the sealing ring (9) and the piston (11) are positioned with the new contact surface, and the return displacement is still the maximum elastic deformation of the sealing ring (9), so the braking clearance is maintained. Same as before wear, the automatic adjustment of the brake clearance is realized.

When the inverse efficiency of the worm (8) and the worm gear (6) is zero, the power can be cut off after the motor (14) is energized to achieve the effect of parking brake, and the self-locking function of the worm gear mechanism can be used to realize the power failure of the motor (14) down the parking brake.

Referring to Fig. 3, another embodiment of the present invention will be described.

The main difference between the embodiment of accompanying drawing 3 and the embodiment of accompanying drawing 1 is as follows:

Transmission mechanism is different, adopts worm gear mechanism transmission in accompanying drawing 1, and worm wheel (6) is the terminal element of transmission mechanism, and one-way clutch (7) is installed between worm wheel (6) and screw rod (5); Adopts in accompanying drawing 3 Two-stage gear transmission, the secondary driven gear (24) is the terminal element of the transmission mechanism, and the one-way clutch (7) is installed between the secondary driven gear (24) and the screw rod (5).

The friction limiting device is different. In the accompanying drawing 1, the sealing ring (9) is used to realize the friction limiting function, and the elastic deformation of the sealing ring (9) is used to store the elastic potential energy; in the accompanying drawing 3, a spring (17) and a snap ring (18) are used. Realize the friction limit function, utilize spring (17) to generate elastic deformation and store elastic potential energy.

The piston positioning device is different. In the accompanying drawing 1, the guide flat key (10) is used so that the piston (11) can only move axially and cannot rotate; in the accompanying drawing 3, the cylindrical roller (16) is used to make the piston (11) only Axial movement, unable to rotate.

The parking brake function is realized in different ways. In the accompanying drawing 1, the inverse efficiency of the worm gear mechanism is zero, and the parking braking under the power failure situation of the motor (14) can be directly realized; in the accompanying drawing 3, an electromagnetic brake is used. (20) Release the motor shaft (19) during power-on, and lock the motor shaft (19) to realize the parking brake under the power-off situation of the motor (14) during power-off.

As shown in Fig. 3, an automobile brake-by-wire includes a brake caliper body (3) movable on a guide pin (2), and the guide pin (2) is fixed on a brake caliper bracket (1). There is a brake disc (13) in the jaw of the brake caliper body (3), and there are friction discs (12) on both sides of the brake disc (13), one is mounted on the brake caliper body (3), and the other is mounted on the piston (11), the piston (11) is installed on the brake caliper body (3) through the cylindrical roller (16) and the snap ring (18), and the snap ring (18) is pushed away from the brake disc ( 13) on one side, the spring (17) is installed on the brake caliper body (3). Cylindrical rollers (16) make the piston (11) move only along the axial direction and cannot rotate. There is a relatively large friction force between the contact surface of the snap ring (18) and the piston (11). When the displacement of the piston (11) is When within the elastic deformation range of the spring (17), there is no relative movement between the contact surfaces of the snap ring (18) and the piston (11). The screw rod (5) is supported on the brake caliper body (3) through a tapered roller bearing (28). The screw rod (5) includes two sections, one section is a threaded section (5B) and the other section is a cylindrical section (5A). One end of the piston (11) is equipped with a friction plate (12), and the other end has an internal thread to cooperate with the threaded section (5B) of the screw rod (5) for installation. The cylindrical section (5A) of the screw rod (5) is used as the inner ring of the one-way clutch (7), and the outer ring of the one-way clutch (7) is fixedly connected with the secondary driven gear (24), and the secondary driven gear (24) , secondary driving gear (23), primary driven gear (22) and primary driving gear (21) constitute a two-stage gear reduction mechanism, and primary driving gear (21) is fixedly connected with the motor shaft (19) of motor (14).

When the brake is working, the motor (14) drives the one-way clutch (7) through the two-stage gear reduction mechanism to combine, drives the screw rod (5) to rotate, and pushes the piston (11) and the brake caliper body (3) to move in the opposite direction. The corresponding friction plates (12) are driven to press against the brake disc (13) with the same force from both sides, so as to realize efficient and reliable braking effect. At this time, the snap ring (18) and the piston (11) move together, the spring (17) is compressed, and the spring (17) undergoes elastic deformation, storing elastic potential energy, and there is no relative contact surface between the snap ring (18) and the piston (11). sports. When the brake is released, the motor (14) drives the two-stage gear reduction mechanism to rotate reversely. At this time, the one-way clutch (7) is separated, the screw rod (5) is in a free state, and the elastic potential energy stored in the spring (17) is released, so that The relative movement of the piston (11) and the brake caliper body (3) drives the screw rod (5) to reversely rotate under the action of the elastic potential energy in the spring (17), and all components return to their original positions.

When the friction plate (12) wears out and the thickness becomes thinner, when the brake works, the motor (14) drives the one-way clutch (7) through the two-stage gear reduction mechanism to combine, and drives the screw (5) to rotate, pushing the piston (11) and The brake caliper body (3) moves relatively, and the elastic deformation of the spring (17) reaches the maximum. When the snap ring (18) is close to the left step surface, the braking effect is not good due to the wear of the friction plate (12). At this time, the motor (14) continues to drive the screw rod (5) to rotate through the combined one-way clutch (7), that is, the piston (11) and the brake caliper body (3) continue to move relative to each other, so the spring (17) maintains the maximum elastic deformation amount, and the piston (11) overcomes the frictional force between the snap ring (18) and cooperates with the snap ring (18) with a new contact surface. When the brake is released, the motor (14) drives the two-stage gear reduction mechanism to reverse, the one-way clutch (7) is separated, and the elastic potential energy of the spring (17) is released, so that the piston (11) and the brake caliper body (3) move relatively , to drive the screw (5) to rotate. At this time, the snap ring (18) and the piston (11) are positioned with the new contact surface, and the return displacement is still the maximum elastic deformation of the spring (17), so the braking clearance is maintained. Same as before wear, the automatic adjustment of the brake clearance is realized.

When the parking brake is required, the motor (14) drives the friction plate (12) to press the brake disc (13) to meet the parking brake requirement, and then the electromagnetic brake (20) is powered off to lock the motor shaft (19 ), keep the braking performance constant, and now the parking brake function under the power failure situation of the motor (14) can be realized. When the electromagnetic brake (20) is energized, the motor shaft (19) is released, and now the magnitude of the braking torque can be freely controlled by the motor (14).

In the embodiment of accompanying drawing 3, one-way clutch (7) can also be arranged in the primary driving gear (21), or in the primary driven gear (22), or in the secondary driving gear (23), then transmission mechanism comprises From the output shaft of the motor to the one-way clutch, the transmission system includes the part from the one-way clutch to the screw.

The third embodiment shown in accompanying drawing 4 is basically the same as the second embodiment shown in accompanying drawing 3, and the difference is that an electromagnetic brake (20) is used in the accompanying drawing 3 to realize the parking when the motor (14) is powered off. Car braking function; among accompanying drawing 4, adopt electromechanical braking device to realize the parking brake function under the situation of motor (14) power failure, concrete work process is as follows:

When the electromagnetic coil (25) is energized, the locking pin (27) is subjected to electromagnetic force to compress the return spring (26), so that the locking pin (27) and the secondary driven gear (24) are not in contact with each other. Braking or release has no effect; when the parking brake is required, the motor (14) drives the friction plate (12) to press the brake disc (13) to meet the parking brake requirement, and then the electromagnetic coil (25) is de-energized , the locking pin (27) is inserted into the teeth of the secondary driven gear (24) under the elastic force of the return spring (26) to maintain the parking brake effect, and the motor (14) can be turned off when the power is turned off. Parking brake function.

The structure and working process of the third kind of embodiment shown in accompanying drawing 4 other parts are all identical with the embodiment in accompanying drawing 3, no longer describe here.

Referring to accompanying drawings 1 and 2, an embodiment of an automobile brake-by-wire control method in the present invention will be described.

As shown in Fig. 1, a kind of automobile brake by wire control method comprises the automobile brake by wire of the present invention, target disk (4), sensor (15), electronic control unit (not shown in the figure). The target disc (4) is fixedly installed on the outer surface of the cylindrical section (5A) of the screw rod (5), and the sensor (15) is installed on the brake caliper body (3) corresponding to the target disc (4) for detecting The state of motion of the target disc (4). When the brake works, the motor (14) drives the screw rod (5) to rotate, and the target disc (4) rotates together with the screw rod (5), and the sensor (15) receives the rotation information of the target disc (4) and transmits it to the electronic control unit, The electronic control unit can calculate the clamping force of the brake in combination with the current of the motor (14), and adjust the braking strength.

In addition to the worm gear mechanism and the gear mechanism, the transmission mechanism can also adopt other transmission methods such as chain drive, belt drive, planetary gear drive, etc. The friction limit device can also be realized by using other structures besides the seal ring, spring/clip ring Similar functions, the piston positioning device can also use various methods such as splines, pins, and non-circular outer surfaces of the piston in addition to the guide flat key and cylindrical roller. The locking mechanism can also use the locking pin to act on other gears or The locking function is realized by means of a special locking ratchet integrated with the gear, or by installing a ratchet pawl mechanism on the motor shaft. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, those of ordinary skill in the art can obtain other All embodiments belong to the protection scope of the present invention.

The present invention has been exemplarily described above in conjunction with the accompanying drawings, and it is obvious that the specific implementation of the present invention is not limited by the above-mentioned manner, as long as various improvements of the method concept and technical solutions of the present invention are adopted, or directly applied to other Occasions, all within the protection scope of the present invention.

Claims (6)

1. An automobile brake by wire, comprising a motor, a transmission mechanism, a one-way clutch, a screw rod, a piston, a friction limiting device, a piston positioning device, a brake caliper body, a brake disc, and a friction plate; segment and cylindrical segment, the screw rod is supported on the brake caliper body, and there is no relative movement between the screw rod and the brake caliper body in the axial direction; the friction plate has two , symmetrically arranged on both sides of the brake disc, one is installed on the piston, and the other is installed on the brake caliper body; the piston is installed on the On the body of the brake caliper, the piston positioning device can only reciprocate the piston in the axial direction, and cannot rotate; the piston has internal threads, which are matched with the threaded section of the screw; the screw The outer surface of the cylindrical section is used as the inner ring of the one-way clutch, and the outer ring of the one-way clutch is fixedly connected with the terminal element of the transmission mechanism; the movement of the terminal element of the transmission mechanism drives the When the outer ring of the one-way clutch rotates, the one-way clutch is combined to drive the screw to rotate, the piston moves, the brake caliper body and the screw move in the opposite direction to the piston, Drive the friction plate to press the brake disc from both sides; the motor is connected to the input element of the transmission mechanism; a part of the friction limiting device is fixedly installed on the brake caliper body On the other hand, there is a relatively large friction force between the other part and the outer surface of the piston. When there is a relative displacement between the piston and the brake caliper body, the friction limit will be caused by the friction force. Elastic potential energy is generated in the device; When braking, the motor drives the outer ring of the one-way clutch to move through the transmission mechanism, and the one-way clutch is combined to drive the screw to rotate, driving the piston and the brake caliper body respectively move in opposite directions, so that the friction plates are pressed against both sides of the brake disc to obtain an efficient and reliable braking effect. At this time, the gap between the piston and the brake caliper body There is a relative displacement, and elastic potential energy is generated in the friction limiting device; when the brake is released, the motor drives the outer ring of the one-way clutch to move backward through the transmission mechanism, and the one-way clutch is separated. , the elastic potential energy inside the friction limiting device causes the piston and the brake caliper to move relative to each other and return to the original position. At this time, the screw rotates to accommodate the piston and the brake caliper. The relative movement of the brake caliper body; When the friction plate is worn and the thickness becomes thinner, when the brake works, the motor drives the one-way clutch through the transmission mechanism to combine, drives the screw to rotate, and makes the piston Relatively moving with the brake caliper body, the elastic potential energy in the friction limiting device reaches the maximum, and the braking effect is not good due to the thinning of the friction plate. At this time, the motor continues to work, driving the screw rod Continue to rotate to overcome the friction between the outer surface of the piston and the friction limiting device, so that the piston and the brake caliper body continue to move relative to each other, and press the brake disc to obtain a reliable Efficient braking effect; when the brake is released, the elastic potential energy in the friction limiting device acts to make the piston and the brake caliper move relative to each other. At this time, the piston and the The friction limit device is relatively fixed with a new contact position, realizing the automatic adjustment of the brake clearance. 2. The automobile brake-by-wire according to claim 1, characterized in that it also includes a recirculating ball structure between the screw and the internal thread of the piston to reduce frictional resistance and improve system operation. efficiency. 3. The brake-by-wire vehicle according to claim 1, further comprising adding a transmission system between said one-way clutch and said screw rod. 4. The brake-by-wire vehicle according to claim 1, further comprising connecting the terminal element of the transmission mechanism with the inner ring of the one-way clutch, and the screw connecting the one-way clutch. To the outer ring of the clutch, when the brake works, the one-way clutch is combined, and when the brake is released, the one-way clutch is disengaged. 5. A brake-by-wire vehicle according to claim 3, characterized in that when there is no transmission link with zero inverse efficiency in the transmission mechanism or the transmission system, the locking mechanism is used to realize the Parking brake when the motor is powered off, the locking mechanism adopts an electromagnetic brake or an electronically controlled mechanical brake device, which can be disconnected when the power is turned on, and the transmission element in the transmission link is fixed when the power is turned off, so as to maintain the The size of the pressure between the friction plate and the brake disc realizes the parking brake function; when the transmission mechanism or the transmission system is provided with a transmission link with zero inverse efficiency, the The locking mechanism realizes the parking brake, and can also use the inverse efficiency to be zero, and the power and motion cannot be transmitted in reverse, so as to realize the parking brake when the motor is powered off. 6. A control method for an automobile brake-by-wire, characterized in that the automobile brake-by-wire described in any one of claims 1-5 is used, and the control method comprises the following steps: when the brake is working, the motor drives the When the transmission mechanism works, the one-way clutch is combined to drive the screw to rotate, drive the piston and the brake caliper body to move, and make the friction plate press the two sides of the brake disc , the electronic control unit detects the rotation information of the screw, and calculates the brake clamping force in combination with the current of the motor; when the friction plate is worn, the electronic control unit controls the rotation of the motor to compensate for the wear impact.