CN117944646A - Electronic hydraulic brake with failure backup - Google Patents

Abstract

The invention is applicable to the technical field of automobiles, and provides an electronic hydraulic brake with failure backup, which comprises the following components: the driving motor is provided with a speed reducing mechanism, the speed reducing mechanism is movably connected with a transmission mechanism, one end of the transmission mechanism is provided with a brake master cylinder piston, and the brake master cylinder piston is movably connected with a brake master cylinder; the push rod is arranged on the brake pedal, the driving motor is hollow, and the push rod penetrates through the driving motor and the transmission mechanism; the angular displacement sensor is arranged on the brake pedal, and is electrically connected with the ECU, and the ECU is electrically connected with the driving motor; the brake pedal feel feedback device is arranged on the driving motor and is movably connected with the push rod; the invention structurally realizes failure backup, when the driving motor fails, the driver can still obtain enough brake pedal feel when the driving motor fails by stepping on the brake pedal to carry out emergency braking.

Description

An electronic hydraulic brake with fail-safe backup

Technical Field

The invention belongs to the technical field of automobiles, and in particular relates to an electronic hydraulic brake with failure backup.

Background technique

With the continuous development and progress of science and technology and the continuous improvement of the performance of automobiles, the safety performance of automobiles has become the main focus of automobile development, and thus the braking performance of automobiles has become increasingly important. Although the traditional hydraulic brake system can already meet the braking requirements required for normal driving of the car, the structure of the traditional hydraulic brake system is relatively complex, and the system also has shortcomings such as slow response speed, poor performance, and insufficient braking force. As an advanced braking system, the electronic hydraulic brake system can not only effectively overcome the defects of the traditional hydraulic brake system, but also provide higher safety and stability. As the core component of the electronic hydraulic brake system, it is necessary to design the electronic hydraulic brake reasonably and effectively.

In the patent proposed by Ma Yuelong et al. (Ma Yuelong, Zhou Yan, Huang Bin, Zhong Wenshi, Huang Yongkuo, Zhao Feng, Wang Wenlu, Zhang Xin, You Zhenjun, Xie Ning, Liu Lijun: CN111137257A [P]), they used a combination of a gear set and a screw nut to save structural space. The working process of the brake is as follows: the driver presses the brake pedal to push the push rod, sleeve, and slider to move. At this time, the displacement sensor detects the movement of the slider and feeds the signal back to the ECU to control the operation of the motor. The torque generated by the motor is transmitted to the screw through the gear set and nut. The screw pushes the main cylinder piston to achieve the purpose of pressure building. In the patent proposed by Ma Yuelong et al., the gear nut and gear set of the electronic hydraulic brake they designed are externally meshed, which not only affects the transmission efficiency but also may be affected by the external environment.

Jo (Jo T, Joo K, Lee J, Control strategy of dual-winding motor for vehicle electro-hydraulic braking systems[J]) et al. proposed a method using a dual-winding motor control strategy. The electronic hydraulic braking system they designed consists of two identical electronic control units (ECUs), a dual three-phase dual-winding permanent magnet synchronous motor (DW-PMSM) and an actuator that generates braking hydraulic pressure. Experimental results show that the control strategy of the system can effectively achieve the functional safety of the entire electronic hydraulic braking system. The entire electronic hydraulic braking system proposed by Jo et al. is highly dependent on the design of its own control algorithm and the execution efficiency of the controller, and is prone to failure, resulting in the inability to achieve its function.

Summary of the invention

The purpose of the embodiments of the present invention is to provide an electronic hydraulic brake with fail-safe backup, aiming to solve the problems existing in the background technology.

The embodiment of the present invention is implemented as follows: an electronic hydraulic brake with fail-safe backup, comprising:

A driving motor, wherein the driving motor is provided with a speed reduction mechanism, wherein the speed reduction mechanism is movably connected to a transmission mechanism, wherein a brake master cylinder piston is provided at one end of the transmission mechanism, and wherein the brake master cylinder piston is movably connected to a brake master cylinder;

A push rod, which is arranged on the brake pedal. The drive motor is hollow in design, and the push rod passes through the drive motor and the transmission mechanism;

An angular displacement sensor, the angular displacement sensor is arranged on the brake pedal, the angular displacement sensor is electrically connected to the ECU, and the ECU is electrically connected to the drive motor;

A brake pedal feeling feedback device is provided on the driving motor and is movably connected to the push rod.

As a further scheme of the present invention, the deceleration mechanism includes a center gear, a gear and a ring gear, the transmission mechanism includes a ball nut and a ball screw, the output shaft of the drive motor is fixedly connected to the center gear, the center gear is meshed with the gear, the gear is rotatably connected to the drive motor, the gear is meshed with the ring gear, the ring gear is fixedly connected to the ball nut, the ball nut is threadedly connected to the ball screw through a threaded connection pair, the brake master cylinder piston is arranged at one end of the ball screw, the ball screw is hollow in design, and the push rod passes through the ball screw.

As a further solution of the present invention, the brake pedal feeling feedback device includes a main body, a spring 1, a spring 2, a pressure block 1 and a pressure block 2, the main body is fixedly connected to the drive motor, the spring is set on the push rod, the push rod is slidably connected to the main body, the main body is slidably connected to the pressure block 1, the two ends of the spring 1 respectively abut against the main body and the pressure block 1, the main body is slidably connected to the pressure block 2, and the two ends of the spring 2 respectively abut against the pressure block 2 and the main body.

Compared with the prior art, the beneficial effects of the present invention are as follows: the ball nut and the gear ring in the present invention are fixedly connected, which not only improves the transmission efficiency of the entire brake, but also ensures that the entire structure has higher stability during operation; and, the present invention integrates the drive motor and the deceleration mechanism into an integrated design, which is simpler and more compact in structure; the present invention achieves a failure backup effect in structure, and when the drive motor fails, the driver can perform emergency braking by stepping on the brake pedal, which is more conducive to the deployment of the brake, and the present invention designs a brake pedal feel feedback device, so that the driver can still obtain sufficient brake pedal feel when the drive motor fails.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the structure of an electronic hydraulic brake with fail-safe backup provided by an embodiment of the present invention;

FIG2 is a target curve diagram of a brake pedal sensor provided by an embodiment of the present invention;

FIG. 3 is a structural diagram of a brake pedal sensory feedback device provided in an embodiment of the present invention.

In the attached drawings: 1-drive motor, 2-push rod, 3-brake pedal sensor, 31-body, 32-spring 1, 33-spring 2, 34-pressure block 1, 35-pressure block 2, 4-center gear, 5-gear, 6-gear ring, 7-ball nut, 8-ball screw, 9-brake master cylinder, 10-brake master cylinder piston.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

The specific implementation of the present invention is described in detail below in conjunction with specific embodiments.

As shown in FIG. 1 to FIG. 3 , an electronic hydraulic brake with fail-safe backup is shown in one embodiment of the present invention, comprising:

A driving motor 1, wherein the driving motor 1 is provided with a speed reduction mechanism, wherein the speed reduction mechanism is movably connected to a transmission mechanism, wherein a brake master cylinder piston 10 is provided at one end of the transmission mechanism, and wherein the brake master cylinder piston 10 is movably connected to a brake master cylinder 9;

A push rod 2, which is arranged on the brake pedal. The drive motor is hollow in design, and the push rod 2 passes through the drive motor 1 and the transmission mechanism;

An angular displacement sensor, wherein the angular displacement sensor is arranged on the brake pedal, the angular displacement sensor is electrically connected to an ECU, and the ECU is electrically connected to the drive motor 1;

A brake pedal feeling feedback device 3 , wherein the brake pedal feeling feedback device 3 is disposed on the driving motor 1 , and the brake pedal feeling feedback device 3 is movably connected to the push rod 2 .

In this embodiment, the brake master cylinder piston 10 is arranged at the end of the push rod 2 away from the brake pedal; the deceleration mechanism includes a central gear 4, a gear 5 and a gear ring 6, the transmission mechanism includes a ball nut 7 and a ball screw 8, the output shaft of the drive motor 1 is fixedly connected to the central gear 4, the central gear 4 is meshed with the gear 5, the gear 5 is rotationally connected to the drive motor 1, the gear 5 is meshed with the gear ring 6, the gear ring 6 is fixedly connected to the ball nut 7, the ball nut 7 is threadedly connected to the ball screw 8 through a threaded connection pair, the brake master cylinder piston 10 is arranged at one end of the ball screw 8, the ball screw 8 is hollow, and the push rod 2 passes through the ball screw 8; the drive motor 1 It is the power source of the entire electronic hydraulic brake, providing power to drive the brake to work normally; the drive motor 1 and the ball screw 8 are designed to be hollow, and the push rod 2 can directly push the brake master cylinder piston 10 through the hollow parts of the drive motor 1 and the ball screw 8; the reduction mechanism includes a central gear 4, a gear 5 and a gear ring 6, and through the transmission principle of the gear, the high-speed and low-torque input of the drive motor 1 is converted into a low-speed and high-torque torque output to provide sufficient power to drive the brake to perform the corresponding operation; the transmission mechanism includes a ball nut 7 and a ball screw 8, which converts the torque output by the reduction mechanism into the lateral linear motion of the ball screw 8, so as to push the brake master cylinder piston 10 to compress the brake master cylinder 9 to form brake fluid pressure;

Conventional working process: the driver pushes the push rod 2 forward by operating the brake pedal. At this time, the angular displacement sensor recognizes the angular displacement signal of the brake pedal and feeds the signal back to the ECU. The ECU controls the drive motor 1 to generate a driving torque, driving the central gear 4 to rotate. The rotation transmits the torque to the ball nut 7 through the reduction mechanism, so that the ball nut 7 rotates. Subsequently, the power is transmitted to the ball screw 8 through the threaded connection pair. The lateral linear motion generated by the ball screw 8 pushes the brake master cylinder piston 10 to compress the brake master cylinder 9, so that the brake master cylinder 9 generates brake fluid pressure to achieve the braking effect;

Failure working process: When the drive motor 1 fails and cannot work normally, the driver pushes the push rod 2 forward through the hollow part of the drive motor 1 and the ball screw 8 by operating the brake pedal, directly pushing the brake master cylinder piston 10 to compress the brake master cylinder 9, so that the brake master cylinder 9 generates brake fluid pressure to achieve the braking effect, and the brake pedal feeling feedback device 3 can provide the driver with sufficient brake pedal feeling;

The calculation and selection process of each major component will be introduced below. The present invention provides a calculation method, and the specific selection needs to be made according to the actual target vehicle model and braking requirements:

1. Driving motor 1

Function: It is the power source of the entire electronic hydraulic brake, providing power to drive the brake to work normally.

The motor torque can be obtained by the following formula (1):

Where: is the torque of driving motor 1, /> is the maximum piston rod thrust of the brake master cylinder 9 during braking, /> is the lead of the ball screw 8, /> is the mechanical efficiency of the ball screw 8, /> is the transmission ratio of the reduction mechanism.

The speed of the driving motor 1 can be obtained by the following formula (2):

Where: is the motor speed, /> is the lateral linear moving speed of the ball screw 8.

in, 、/> 、/> In the selection of the ball screw 8 below, determine, /> The overall parameters of the motor are determined in the selection of the reduction mechanism below, so the overall parameters of the motor are finally determined by/> The decision should be made based on the maximum piston push rod force required by the actual target vehicle model during braking.

(II) Speed reduction mechanism

Function: Convert high-speed, low-torque motor input into low-speed, high-torque torque output to provide sufficient power to drive the brake to perform corresponding operations.

The reduction mechanism selected for this design is a gear reduction mechanism. In order to facilitate better integration of the gear reduction mechanism and the drive motor 1, the structural dimensions of the gear reduction mechanism should be designed according to the overall outer dimensions of the selected drive motor 1. Therefore, the size of the ring gear 6 can be determined according to the size of the selected drive motor 1.

The center distance d between the center gear 4 and the gear 5 can be calculated by formula (3):

Where: is the module of gear 5, /> is the number of teeth of the central gear 4, /> The number of teeth on gear 5.

The size relationship between the central gear 4, gear 5 and ring gear 6 in the gear reduction mechanism is shown in formula (4):

Where: The number of teeth on the ring gear is 6.

The transmission ratio calculation of the gear reduction mechanism is shown in formula (5):

Where: is the transmission ratio of the gear reduction mechanism.

The module of gear 5 should be a standard value, and should be selected starting from the first series. The selected module must satisfy the requirement that the number of teeth of gear 5 calculated by the above three formulas is an integer value.

(III) Ball screw 8 and ball nut 7

Function: Convert the torque output by the gear reduction mechanism into the lateral linear motion of the ball screw 8, thereby pushing the piston to compress the brake master cylinder 9 to form brake fluid pressure.

Assume that the piston stroke required by the brake master cylinder 9 is (Select the stroke of the brake master cylinder piston 10 according to the specific braking requirements). According to the braking requirements, the pressure building time of the brake master cylinder 9 during emergency braking of the car cannot exceed 0.4s, otherwise it will cause the braking stroke to be too long, affecting the safety of use.

The lateral linear moving speed of the ball screw 8 can be calculated by the following formula (6):

Where: is the lateral linear moving speed of the ball screw 8, /> is the pressure building time of the brake master cylinder 9, /> is the stroke of the brake master cylinder piston 10. According to the calculation, the lateral linear moving speed of the ball screw 8 can be obtained, and the selection requirements of the ball screw 8 can be determined, so the lead of the ball screw 8 can be determined.

The rotation speed of the ball nut 7 can be calculated by formula (7):

Where: is the lateral linear moving speed of the ball screw 8, /> is the lead of the ball screw 8.

Since emergency braking is not performed in most cases during the use of the vehicle, the linear moving speed of the ball screw 8 and the rotational speed of the ball nut 7 are usually smaller than the values calculated above.

Please refer to Figures 1 to 3. In one embodiment of the present invention, the brake pedal sensory feedback device 3 includes a body 31, a spring 1 32, a spring 2 33, a pressure block 1 34 and a pressure block 2 35. The body 31 is fixedly connected to the drive motor 1, the spring 1 32 is sleeved on the push rod 2, the push rod 2 is slidably connected to the body 31, the body 31 is slidably connected to the pressure block 1 34, the two ends of the spring 1 32 respectively abut against the body 31 and the pressure block 1 34, the body 31 is slidably connected to the pressure block 2 35, and the two ends of the spring 2 33 respectively abut against the pressure block 2 35 and the body 31.

In this embodiment, the brake pedal feeling feedback device 3 enables the driver to obtain sufficient brake pedal feeling when the car is braking; the brake pedal feeling is mainly described according to the relationship curve between the brake pedal force and the brake pedal displacement. The target curve of the brake pedal feeling feedback device 3 designed this time is shown in Figure 2 (statistical data of a certain car model, which can be applied to the needs of most drivers for brake pedal feeling, and can be recalculated according to specific actual needs if there is any other need);

This design adopts a double spring structure to meet the target curve requirements. The A-B section is realized by the preload of the spring 1 32, the B-C section is realized by the compression deformation of the spring 1 32, and the C-D section is realized by the compression deformation of the spring 1 32 and the spring 2 33 in parallel.

The stiffness calculation of spring 32 is shown in formula (8):

Where: is the stiffness of spring 1 32, /> is the push rod force at point B, /> is the push rod force at point C, /> For the displacement of push rod 2 from point B to point C, substitute the design data to obtain the stiffness of spring 132/> =1.81N/mm.

The stiffness calculation of spring 2 33 is shown in formula (9):

Where: is the stiffness of spring 2 33, /> is the total elastic coefficient from point C to point D, /> is the stiffness of spring 1 32, /> is the push rod force at point C, /> is the push rod force at point D, /> For the displacement of push rod 2 from point C to point D, substitute the design data to obtain the stiffness of spring 2 33/> =22.22N/mm.

In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims (3)

1. An electro-hydraulic brake having a fail-back, comprising:

The brake device comprises a driving motor, wherein a speed reducing mechanism is arranged on the driving motor, the speed reducing mechanism is movably connected with a transmission mechanism, one end of the transmission mechanism is provided with a brake master cylinder piston, and the brake master cylinder piston is movably connected with a brake master cylinder; the push rod is arranged on the brake pedal, the driving motor is designed in a hollow mode, and the push rod penetrates through the driving motor and the transmission mechanism;

the angular displacement sensor is arranged on the brake pedal, and is electrically connected with an ECU, and the ECU is electrically connected with the driving motor;

And the brake pedal feel feedback device is arranged on the driving motor and is movably connected with the push rod.

2. The electro-hydraulic brake with fail-safe according to claim 1, wherein the reduction mechanism comprises a sun gear, a gear and a ring gear, the transmission mechanism comprises a ball nut and a ball screw, an output shaft of the drive motor is fixedly connected with the sun gear, the sun gear is meshed with the gear, the gear is rotatably connected with the drive motor, the gear is meshed with the ring gear, the ring gear is fixedly connected with the ball nut, the ball nut is in threaded connection with the ball screw through a threaded connection pair, the brake master cylinder piston is arranged at one end of the ball screw, the ball screw is hollow, and the push rod penetrates through the ball screw.

3. The electro-hydraulic brake with fail-safe function according to claim 1, wherein the brake pedal feel feedback device comprises a body, a first spring, a second spring, a first pressing block and a second pressing block, wherein the body is fixedly connected with the driving motor, the first spring is sleeved on the push rod, the push rod is in sliding connection with the body, the body is in sliding connection with the first pressing block, two ends of the first spring respectively abut against the body and the first pressing block, the body is in sliding connection with the second pressing block, and two ends of the second spring respectively abut against the second pressing block and the body.