CN109515418B

CN109515418B - Mechanical actuating mechanism of electronic hydraulic braking system

Info

Publication number: CN109515418B
Application number: CN201811491711.8A
Authority: CN
Inventors: 张志勇; 李博浩; 黄彩霞
Original assignee: Changsha University of Science and Technology
Current assignee: Changsha University of Science and Technology
Priority date: 2018-12-07
Filing date: 2018-12-07
Publication date: 2021-07-02
Anticipated expiration: 2038-12-07
Also published as: CN109515418A

Abstract

The invention discloses a mechanical actuating mechanism of an electronic hydraulic braking system, which comprises a speed-reducing and torque-increasing mechanism, a motion conversion mechanism, a clearance adjusting mechanism, a split type shell, a hydraulic cylinder and a motor, wherein the speed-reducing and torque-increasing mechanism is arranged on the shell; the invention uses the planetary gear train as a speed-reducing torque-increasing mechanism, increases the torque of the motor and transmits the torque to the cylinder, four circular arc-shaped tracks with gradually-reduced slope are arranged on the cylinder from bottom to top, and the upper track surface and the lower track surface have certain slope; the circular truncated cone rolling bodies are arranged in the circular arc-shaped tracks; the circular truncated cone rolling bodies are driven to roll upwards along the rail surface from the lowest position of the lower rail surface of the circular arc-shaped rail on the cylinder through circumferential rotation of the cylinder, the support, the push rod and the push plate are pushed to generate axial displacement, the piston is further pushed to move upwards, and hydraulic pressure acting on the brake wheel cylinder is generated. The mechanical actuating mechanism of the electronic hydraulic braking system disclosed by the invention has the advantages of reliable braking, adjustable clearance, high response speed and the like.

Description

Mechanical actuating mechanism of electronic hydraulic braking system

Technical Field

The invention relates to the field of automobile brake-by-wire, in particular to the field of an electronic hydraulic brake system.

Background

With the continuous progress of science and technology and the continuous increase of automobile holding capacity, the requirement of people on the safety performance of automobiles is increased day by day. The excellent braking performance and the integrated chassis comprehensive control technology are an important evaluation index of the safety of modern automobiles. Although the traditional vehicle braking system can meet various requirements of the existing braking law on braking performance, the traditional vehicle braking system also has the defects of low braking efficiency, slow response, complex structure, difficult maintenance, environmental pollution caused by brake fluid and the like. Therefore, a brake-by-wire system which is expected to solve the above problems has been proposed, and a brake-by-wire system has been developed.

Brake-by-wire systems are mainly divided into two categories: electromechanical brake systems and electrohydraulic brake systems.

The electromechanical braking system mainly comprises a power supply, a motor, a speed-reducing and torque-increasing mechanism, a motion conversion device, a sensor and an electronic control unit. During braking, a driver steps on a brake pedal, and a pedal pressure sensor and a pedal displacement sensor transmit pedal force and pedal displacement signals to the electronic control unit. The electronic control unit inputs corresponding current to the motor through calculation to control the motor to output a certain rotating speed and torque, the rotating speed and the torque are reduced by the speed reduction and torque increase mechanism, the torque is increased and then transmitted to the motion conversion mechanism, the motion conversion mechanism converts the rotating motion from the motor into translational motion, and the friction plate is further pushed to be in contact with the brake disc to generate braking. The electronic mechanical brake adopts the mode of combining the electronics and the machinery to brake, so that the traditional hydraulic pipeline and vacuum brake are thoroughly abandoned in the aspect of energy transmission, and the motor is used as a driving mechanism for braking, so that the electronic mechanical brake has the characteristics of light weight and quick braking. The electromechanical brake system is regarded as the main form of the future brake execution system, but the key problems of vehicle-mounted 42V power supply, reliability, fault tolerance, interference resistance and the like still need to be solved, so that the electromechanical brake system cannot be widely applied

The electronic hydraulic brake system is developed on the basis of a traditional hydraulic brake and consists of a brake pedal unit, a hydraulic driving unit, a sensor, a brake execution unit and an electronic control unit. During braking, a driver steps on a brake pedal, and the pedal unit generates reaction force to simulate pedal feeling. The pedal pressure sensor and the pedal displacement sensor transmit pedal force and pedal displacement signals to the electronic control unit, the electronic control unit controls the hydraulic driving unit to generate corresponding hydraulic pressure through calculation, and the hydraulic pressure acts on the brake execution unit to generate a braking effect. The hydraulic driving unit generates hydraulic pressure in two schemes, one scheme is that a hydraulic pump and a high-pressure accumulator are adopted, and the master cylinder pressure or the wheel cylinder pressure is provided through the high-pressure energy of the high-pressure accumulator. One is an electric motor and a speed reducing mechanism, and the electric motor converts torque into thrust on a linear motion mechanism so as to push a master cylinder or a hydraulic cylinder piston to generate brake pressure. The electro-hydraulic brake has the advantages of compact structure, improved braking efficiency, low noise and better pedal feel.

The electronic hydraulic brake system is a novel brake system, the development time is short, but the development prospect is very wide, and all automobile manufacturers and research institutions are actively developing the system. The electronic hydraulic system is developed on the basis of the original hydraulic braking system, so that a hydraulic pump and a high-pressure accumulator are frequently used as sources of hydraulic driving force in the market. The electronic hydraulic brake system adopting the scheme of the hydraulic pump and the high-pressure accumulator needs an additional high-pressure source, and the hydraulic hysteresis characteristic of the electronic hydraulic brake system hardly reflects the response rapidity of the brake-by-wire system completely. For this reason, various colleges and universities began research relating to new forms of electro-hydraulic brake systems. For example, the university of Tongji in Zhuo Ping team developed an electronic hydraulic brake system with a novel decoupling mode, and applied for related patents. As in application No.: 201510123264.0, the patent uses a brake pedal with a latch to input the driver's braking intention to a control unit, the latch cooperating with a slide slot of a screw to effect mechanical decoupling. The push rod with the sliding groove is mechanically connected with the screw rod of the ball screw in a hinged mode. The ball screw pushes the master cylinder piston to generate braking force. The wang of the university of qinghua develops a distributed electronic hydraulic brake system for automobiles, and related patents are applied. As in application No. 201110095263.1, the patent uses a dc motor as a driving source, and the rotation of the motor shaft drives a piston through a ball screw pair, and the piston generates a braking pressure to act on a wheel cylinder through a pipeline.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a mechanical actuating mechanism of an electronic hydraulic brake system.

In order to achieve the purpose, the invention adopts the following technical scheme:

a mechanical actuating mechanism of an electronic hydraulic braking system comprises a speed-reducing and torque-increasing mechanism, a motion conversion mechanism, a clearance adjusting mechanism, a split type shell, a hydraulic cylinder and a motor; the speed reduction and torque increase mechanism is used for greatly reducing the rotating speed and increasing the torque of the motor and comprises a sun gear, three large planetary gears, three small planetary gears, a planet carrier and a gear ring; the motion conversion mechanism converts the rotary motion of the motor into linear motion and comprises a cylinder, a circular truncated cone rolling body with small taper and a bracket; the clearance adjusting mechanism is used for adjusting the initial position of the piston in the hydraulic cylinder and comprises a coupler, a push rod and a push plate; the split housing is used to protect the internal mechanical structure. The hydraulic cylinder is filled with brake fluid, and the brake fluid enters the brake through the brake pipeline under the pushing of the piston to generate hydraulic pressure.

The shaft of the sun gear of the speed reduction and torque increase mechanism is directly connected with a motor shaft, the sun gear is meshed with three big planetary gears, the three big planetary gears are distributed in an equiangular mode through a central axis, and the big planetary gears revolve around the sun gear and rotate at the same time; the three big planetary gears and the three small planetary gears are respectively fixedly connected, and the big planetary gears and the small planetary gears have the same rotating speed and rotating direction; three small planet gears are meshed with the gear ring; the gear ring is fixed on the split type shell; the planet carrier is used for supporting the big planetary gear and the small planetary gear and rotates along with the big planetary gear and the small planetary gear, and the rotating speed is the same as the revolution speed of the big planetary gear and the small planetary gear; one end of the planet carrier, which is close to the small planet gear, is embedded into the lower end of the cylinder of the motion conversion mechanism to drive the cylinder to rotate circumferentially, and a thrust ball bearing is arranged between the planet carrier and the motor and used for offsetting brake counter force.

Four circular arc-shaped rails with gradually reduced slopes are arranged on a cylinder of the motion conversion mechanism from bottom to top, penetrate through the inner wall of the cylinder and are distributed along the circumference at equal angles by the central axis, and further, the upper and lower rail surfaces of each circular arc-shaped rail are provided with a certain slope and the inclined directions are inward; the circular truncated cone rolling body is arranged in the circular arc-shaped track, the large end of the circular truncated cone rolling body faces outwards, and the small end of the circular truncated cone rolling body faces inwards; the taper of the circular truncated cone rolling body is consistent with the inclination of the upper and lower orbital planes in value; two ends of the circular truncated cone rolling body are connected with the lower end of the bracket in a pin connection mode.

Furthermore, a section of small-pitch thread is formed at the upper end of the push rod, and the neck at the upper end of the push rod is screwed into the two nuts in advance. The push plate is provided with a threaded hole, the threaded hole is matched with the upper end of the push rod in a threaded manner, and the upper end of the push rod is screwed into the threaded hole and penetrates through the push plate. The push rod and the push plate can be locked by screwing down the two nuts at the neck part at the upper end of the push plate. The lower end of the push rod is a polish rod which is connected with the upper end of the bracket through a coupler,

furthermore, a fixing frame is arranged between the upper ends of the four supports and the coupler, so that the supports are prevented from swinging in the braking process, and the stability of the mechanical actuating mechanism is improved.

Five threaded holes are symmetrically arranged on the split surface of the split shell in the left-right direction, and the split shell is positioned and connected through outer hexagonal reamed hole bolts to form an integral shell.

Furthermore, the piston is fixed on the push plate, four semicircular grooves distributed along the circumference at equal angles are formed in the edge of the push plate, and the semicircular guide rails of the semicircular groove split type shell are in clearance fit to prevent the push plate from rotating in the circumferential direction. The top end of the semicircular guide rail is provided with a threaded hole, and the hydraulic cylinder is fixed on the split type shell through a bolt.

The invention has the beneficial effects that: the mechanical actuating mechanism adopts the planetary gear train as the speed-reducing torque-increasing mechanism, compared with the gear as the speed-reducing torque-increasing mechanism, the radial size of the mechanical actuating mechanism can be reduced, meanwhile, the transmission of the planetary gear train has the advantages of large transmission ratio and high efficiency, and better speed-reducing torque-increasing effect can be achieved; the motion conversion mechanism utilizes the circular truncated cone rolling bodies to roll in an arc-shaped track with gradually reduced slope from bottom to top to generate axial displacement, thereby realizing the braking function; furthermore, the slope of the track is gradually reduced from bottom to top, the slope of the circular truncated cone rolling element is larger in the initial braking stage, larger axial displacement can be generated, the brake lining is not in contact with the brake disc at the moment, the brake resistance is small, and the clearance between the brake lining and the brake caliper can be eliminated quickly; as the circular truncated cone rolling bodies continue to roll, the slope of the track surface gradually becomes smaller, the axial force gain effect becomes larger, and the generated braking force is increased; the contact between the circular truncated cone rolling body and the track surface is linear contact, so that the fatigue strength can be improved; when the automobile is used for a long time, the brake lining is abraded to cause the reduction of the brake performance, the push plate and the push rod adopt a mode of thread connection with a small screw pitch, and the relative position of the piston on the hydraulic cylinder is adjusted by adjusting the push rod to recover the brake performance.

Drawings

Fig. 1 is a schematic cross-sectional view of a mechanical actuator according to an embodiment of the present invention.

Fig. 2 is a schematic mounting diagram of a planetary gear train of the mechanical actuator in the embodiment of the invention.

Fig. 3 is a split housing of a mechanical actuator in an embodiment of the invention.

FIG. 4 is a push plate of a mechanical actuator according to an embodiment of the present invention.

Fig. 5 is a hydraulic cylinder of a mechanical actuator according to an embodiment of the present invention.

FIG. 6 is a push rod of a mechanical actuator according to an embodiment of the present invention.

Fig. 7 is a fixing frame of a mechanical actuator according to an embodiment of the present invention.

Fig. 8 is a bracket of a mechanical actuator in an embodiment of the invention.

Fig. 9 is a cylinder of a mechanical actuator in an embodiment of the present invention.

Fig. 10 shows a circular table rolling element of a mechanical actuator according to an embodiment of the present invention.

In the figure: 1-a motor; 6-split housing; 21-sun gear; 22-big planetary gear; 25-minor planet gear; 46-a coupling; 42-a push plate; 31-a scaffold; 5-a hydraulic cylinder; 51-a piston; 52-sealing ring; 44-a push rod; 45-a nut; 43-a holder; 33-a cylinder; 32-circular truncated cone rolling elements; 23-a gear ring; 24-a planet carrier; 7-thrust ball bearing.

Detailed Description

The invention will be further explained and explained with reference to the drawings, in which:

embodiment 1, as shown in fig. 1, includes a speed reduction and torque increase mechanism 2, a motion conversion mechanism 3, a gap adjustment mechanism 4, a split case 6, a hydraulic cylinder 5, and a motor 1; the speed reduction and torque increase mechanism 2 is used for reducing the rotating speed and increasing the torque of the motor 1 and comprises a sun gear 21, three large planetary gears 22, three small planetary gears 25, a planet carrier 24 and a gear ring 23; the motion conversion mechanism 3 is used for converting a rotational motion from the motor 1 into a linear motion, and includes a cylinder 33, a circular truncated cone rolling element 32 with a small taper, and a bracket 31; the clearance adjusting mechanism 4 is used for adjusting the initial position of the piston 51 in the hydraulic cylinder 5 and comprises a coupler 46, a push rod 44, a push plate 42 and the piston 51; the split housing 6 serves to protect the internal mechanical structure.

The speed reduction and torque increase mechanism 2 is mainly composed of a planetary gear train, and the installation schematic diagram of the planetary gear train is shown in fig. 2. The shaft of the sun gear 21 is directly connected with the shaft of the motor 1, the sun gear 21 is meshed with three big planetary gears 22, the three big planetary gears 22 are distributed with equal angles on the central axis, and the big planetary gears 22 revolve around the sun gear 21 and rotate; the three big planetary gears 22 are respectively and fixedly connected with the three small planetary gears 25; the inner wall of the split type shell 6 is provided with a groove, and the gear ring is arranged in the groove and fixed; the planet carrier 24 is used for supporting the big planet gears 22 and the small planet gears 25 and rotating along with the big planet gears 22 and the small planet gears 25, and the rotating speed is the same as the revolving speed of the big planet gears 22 and the small planet gears 25; one end of the planet carrier 24 close to the small planet gear 25 is embedded into the lower end of the cylinder 33 of the motion conversion mechanism 3 to drive the cylinder 33 to rotate circumferentially; a thrust ball bearing 7 is mounted between the planet carrier 24 and the motor 1 for counteracting the braking reaction.

The structure of the cylinder 33 of the invention is shown in fig. 9, four circular arc tracks with gradually reduced slope are arranged on the cylinder 33 from bottom to top, the four circular arc tracks penetrate through the inner wall of the cylinder 33 and are distributed along the circumference with equal angle by the central axis, further, the upper and lower track surfaces of each circular arc track have certain slope, and the slope directions are both inward; the circular truncated cone rolling body 32 is arranged in the circular arc-shaped track, the large end of the circular truncated cone rolling body 32 faces outwards, and the small end of the circular truncated cone rolling body faces inwards; the taper of the circular truncated cone rolling body 32 is consistent with the inclination of the upper and lower orbital planes in value; the two ends of the circular truncated cone rolling body 32 are connected with the lower end of the bracket 31 in a pin connection mode.

The structure of the push rod 44 of the present invention is shown in fig. 6, the upper end of the push rod 44 is provided with a section of small-pitch thread, and the neck part of the upper end of the push rod 44 is screwed into two nuts 45 in advance. The push plate 42 is provided with a threaded hole which is matched with the upper end of the push rod 44 in a threaded manner, and the upper end of the push rod 44 is screwed into the threaded hole and penetrates through the push plate 42. The relative position of the piston 51 can be adjusted by adjusting the amount of precession of the push rod 44. After the adjustment is completed, the push rod 44 and the push plate 42 can be locked by screwing off two nuts at the neck part at the upper end of the push rod 44. The lower end of the push rod 44 is a polished rod and is connected with the upper end of the bracket 31 through a coupler 46, and the cylindrical push block is fixed on the push plate 42.

The structure of the circular truncated cone rolling element 32 of the invention is shown in fig. 10, and the circular truncated cone rolling element 32 has a certain taper. When braking, an inward bending moment will be generated. When the brake is released, an outward bending moment is generated. In order to eliminate the bending moment, a fixing frame 43 is arranged between the bracket and the coupler to offset the bending moment, and meanwhile, the bracket is prevented from swinging in the braking process, and the stability of the electronic mechanical brake is improved.

The invention adopts a split-type shell 6, the structure of the split-type shell 6 is shown in figure 3, five threaded holes are symmetrically arranged on the left and right of the split surface of the split-type shell 6, and the split surface is positioned and connected through an outer hexagonal reamed hole nut to form an integral shell.

The structure of the push plate of the invention is shown in figure 4, the edge of the push plate 42 is provided with four semicircular grooves which are distributed along the circumference at equal angles, and the semicircular grooves are in clearance fit with the raised semicircular arc track on the split shell 6 to prevent the push plate 42 from generating circumferential rotation.

Further, the piston 5 is fixed on the push plate 42, four semicircular grooves distributed at equal angles are formed in the edge of the push plate 42, and a semicircular guide rail is arranged on the inner wall of the split type shell 2 to prevent the push plate 42 from rotating circumferentially. The top end of the semicircular guide rail is provided with a threaded hole, and the hydraulic cylinder 5 is fixed on the split type shell 2 through a bolt.

The working principle of the invention is as follows: the motor 1 drives the sun gear 21 to rotate, and simultaneously drives the three large planetary gears 22 which are meshed with each other to revolve around the sun gear 21. The three big planetary gears 22 are fixedly connected with the three small planetary gears 25, i.e. the big planetary gears 22 and the small planetary gears 25 have the same rotation speed and rotation direction. The pinion gears 25 mesh with the ring gear 23, the ring gear 23 is fixed to the split case 6, and the cylinder 33 is fixed to the carrier 24 to rotate circumferentially together with the carrier 24. It is achieved that the output torque of the motor 1 is transmitted to the cylinder 33 via an increase. When the planet carrier 24 drives the cylinder 33 to rotate circumferentially, the driving circular truncated cone rolling elements 32 roll upward along the track surface from the lowest position of the lower track surface of the circular arc track on the cylinder 33. Because the semicircular groove on the push plate 42 is in clearance fit with the raised track of the split housing, circumferential rotation of the push plate 42, push rod 44 and bracket 31 does not occur. The lower end of the support 31 is connected with two ends of the circular truncated cone rolling body 32, the rolling of the circular truncated cone rolling body 32 pushes the support 31 to generate axial displacement, the axial displacement acts on the push plate 42 through the push rod 44, and the push plate 42 pushes the piston 51 to generate braking pressure. Because the slope of the track gradually decreases from bottom to top, the circular truncated cone rolling body 32 can generate larger axial displacement at the initial braking stage, and the clearance between the brake lining and the brake disc can be eliminated quickly. As the circular truncated cone rolling elements 32 continue to roll, the slope of the raceway surface gradually decreases, the axial displacement decreases, the axial force gain effect increases, and the generated hydraulic pressure increases.

During braking, the output torque of the motor 1 is controlled by adjusting the input current and the duty ratio of the motor 1. The torque of the motor 1 is amplified and transmitted to the cylinder 33 through the speed reducing and torque increasing mechanism, and then the circular truncated cone rolling bodies 32 arranged in the circular arc-shaped tracks on the cylinder 33 are driven to roll to corresponding positions to generate certain axial displacement, so that the hydraulic pressure of the brake wheel cylinder is adjusted.

When the brake is released, the control motor 1 rotates in the reverse direction, the output torque is amplified and transmitted to the cylinder 33, the cylinder 33 rotates in the reverse direction, the circular truncated cone rolling elements 32 are driven to roll along the upper rail surface of the upper rail of the cylinder 32, the bracket 31 is pulled back, the push plate 42 and the piston 51 are further pulled back, and the wheel cylinder pressure is reduced.

For the sake of brevity in description, the above-described embodiments are to be construed as merely illustrative of the principles of the present invention and not limitative of the present invention. Modifications to the invention that do not depart from the spirit and substance of the invention will be suggested to those skilled in the art and are intended to be included within the scope of the appended claims.

Claims

1. A mechanical actuator of an electro-hydraulic brake system, characterized by: comprises a speed-reducing and torque-increasing mechanism (2), a motion conversion mechanism (3), a gap adjusting mechanism (4), a split type shell (6), a hydraulic cylinder (5) and a motor (1); the speed reduction and torque increase mechanism (2) is used for reducing the rotating speed and increasing the torque of the motor (1) and comprises a sun gear (21), three large planetary gears (25), three small planetary gears (25), a planet carrier (24) and a gear ring (23); the motion conversion mechanism (3) converts the rotary motion from the motor (1) into linear motion, and comprises a cylinder (33), a circular truncated cone rolling body (32) with small taper and a bracket (31); the clearance adjusting mechanism (4) is used for adjusting the initial position of the piston (51) in the hydraulic cylinder (5) and comprises a coupler (46), a push rod (44), a push plate (42) and the piston (51); the split shell (6) is used for protecting internal mechanical structures; the hydraulic cylinder (5) is filled with brake fluid, and the brake fluid enters the brake through a brake pipeline under the pushing of the piston (51) to generate hydraulic pressure;

the shaft of a sun gear (21) of the speed reduction and torque increase mechanism (2) is directly connected with the shaft of the motor (1), the sun gear (21) is meshed with three large planetary gears (25), the three large planetary gears (25) are distributed in an equiangular mode with the central axis, and the large planetary gears (25) revolve around the sun gear (21) and rotate at the same time; the three big planetary gears (25) are respectively and fixedly connected with the three small planetary gears (25), and the big planetary gears (25) and the small planetary gears (25) have the same rotating speed and rotating direction; three small planet gears (25) are meshed with the gear ring (23); the gear ring (23) is fixed on the split type shell (6); the planet carrier (24) is used for supporting the big planetary gear (25) and the small planetary gear (25) and rotates along with the big planetary gear (25) and the small planetary gear (25), and the rotating speed is the same as the revolving speed of the big planetary gear (25) and the small planetary gear (25); one end of the planet carrier (24) close to the small planet gear (25) is embedded into the lower end of the cylinder (33) of the motion conversion mechanism (3) to drive the cylinder (33) to rotate circumferentially; a thrust ball bearing is arranged between the planet carrier (24) and the motor (1) and is used for offsetting brake counter force;

four arc-shaped rails with gradually reduced slopes are arranged on a cylinder (33) of the motion conversion mechanism (3), penetrate through the inner wall of the cylinder (33) and are distributed along the circumference at equal angles by the central axis, and further, the upper and lower rail surfaces of each arc-shaped rail have certain slopes and the inclined directions are inward; the circular truncated cone rolling element (32) is arranged in the circular arc-shaped track, the large end of the circular truncated cone rolling element faces outwards, and the small end of the circular truncated cone rolling element faces inwards; the taper of the circular truncated cone rolling body (32) is consistent with the inclination of the upper and lower orbital planes in value; two ends of the circular truncated cone rolling body (32) are connected with the lower end of the bracket (31) in a pin connection mode;

the upper end of the push rod (44) is provided with a section of small-pitch thread, and the neck part of the upper end of the push rod (44) is screwed into the two nuts in advance; a threaded hole is formed in the push plate (42), the threaded hole is matched with the upper end of the push rod (44) in a threaded manner, and the upper end of the push rod (44) is screwed into the threaded hole and penetrates through the push plate (42); two nuts (45) at the neck part at the upper end of the push rod (44) are screwed off, so that the push rod (44) and the push plate (42) can be locked; the lower end of the push rod (44) is a polish rod and is connected with the upper end of the bracket (31) through a coupler (46).

2. A mechanical actuator of an electro-hydraulic brake system as set forth in claim 1, wherein: a fixing frame (43) is arranged between the upper ends of the four supports (31) and the coupler (46), so that the supports (31) are prevented from swinging in the braking process, and the stability of a mechanical actuating mechanism is improved.

3. A mechanical actuator of an electro-hydraulic brake system as set forth in claim 1, wherein: five threaded holes are symmetrically arranged on the split surface of the split shell (6) in the left-right direction and are connected in a positioning mode through outer hexagonal reamed hole nuts to form an integral shell.

4. A mechanical actuator of an electro-hydraulic brake system as set forth in claim 1, wherein: the cylindrical push block is fixed on the push plate (42), four semicircular grooves which are distributed along the circumference at equal angles are formed in the edge of the push plate (42), and the split shell (6) is provided with a semicircular guide rail to prevent the push plate (42) from rotating in the circumferential direction; the top end of the semicircular guide rail is provided with a threaded hole, and the hydraulic cylinder (5) is fixed on the split type shell (6) through a bolt.