JP2572597Y2 - Brake actuator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention is used in, for example, an anti-skid brake system or an automatic brake system, and is a type of brake actuator in which a plunger for controlling pressure is reciprocated by rotation of an electric motor. About.

[0002]

2. Description of the Related Art This type of brake actuator includes:
There is one disclosed in JP-A-3-5270. This includes a main body having a cylinder hole formed therein, a drive member extending into the cylinder hole and being rotatable or rotatable by an electric motor, and fitted to the drive member via a screw to be able to reciprocate in the cylinder hole. A driven member, a plunger capable of increasing or decreasing the volume of a pressure chamber defined in the cylinder hole in accordance with the reciprocating motion of the driven member, and a detent portion for preventing rotation of the driven member with respect to the main body. It is provided with.

[0003]

In this conventional brake actuator, in order to prevent rotation of the driven member with respect to the main body, a rotation preventing portion is provided so that the driven member and the main body are unevenly arranged in the circumferential direction. Although the engaging flange portion and the aligning edge portion are provided, if the radial play in the rotation preventing portion is large, the radial play in the screw between the driving member and the driven member increases, so that the operation is performed. At this time, there is a problem that the driven member and the plunger are difficult to reciprocate smoothly, and the responsiveness is reduced.

Therefore, in order to prevent the above-mentioned shaft center misalignment, it is conceivable to fit the driven member and the driving member using a screw (for example, a ball screw or the like) with less play in the radial direction. The cost is increased due to the complexity of screws and strict processing accuracy requirements.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and a screw portion between a driven member and a driven member can be made simple and inexpensive, and the deviation of the axis of the driven member from the cylinder hole can be reduced. It is an object of the present invention to provide a brake actuator capable of preventing the driven member from moving smoothly.

[0006]

In order to achieve the above object, a brake actuator according to the present invention comprises a main body having a cylinder hole, and a driving member extending in the cylinder hole and capable of rotating or rotating by an electric motor. A driven member fitted to the driving member via a screw and capable of reciprocating in the cylinder hole; and increasing and decreasing the volume of the pressure chamber partitioned in the cylinder hole in accordance with the reciprocating movement of the driven member. A brake actuator having a plunger capable of rotating the rotation of the driven member with respect to the main body, wherein the rotation preventing portion is configured such that the driven portion of the cylinder hole is driven.
The inner surface shape of the fitting portion to the member is substantially a regular polygonal hole shape,
And the part corresponding to the apex angle is formed on the inner arc surface,
The outer surface of the driven member has a substantially regular polygonal prism shape, and
The portion corresponding to the apex angle of is formed on the outer arc surface,
A guide portion is provided for engaging the arc surface with the outer arc surface , positioning the driven member in the radial direction with respect to the cylinder hole, and slidably guiding the driven member.

The guide portion is provided with a resin layer interposed between the guide portion and the driven member.

[0008]

In the above-described brake actuator of the present invention, when the driven member reciprocates in accordance with the rotation of the driving member or the rotation of the driving member, the inner arc surface of the apex angle of the regular polygonal hole is used.
Since the guide portion engages the outer circular surface of the apex angle of the regular polygonal column with the cylinder hole, it is positioned in the radial direction with respect to the cylinder hole. However, it is guided and moved in the axial direction of the cylinder hole without any radial movement.

Further, even if the driven member slides with respect to the guide portion, the sliding resistance is reduced by the resin layer.

[0010]

Embodiment 1 Embodiment 1 of the present invention will be described below with reference to FIG.

FIG. 1 shows a brake actuator used in an anti-skid brake system.

In FIG. 1, 1 is a brake actuator.
2 is a main body, which is a cylinder hole 3 penetrating in the axial direction.
An outlet port 4 communicating with the cylinder hole 3 is open on the peripheral surface of one end, and the peripheral surface of the other end is
A flange portion 5 extending radially outward is formed. The flange portion 5 is provided with a mounting hole 5a penetrating in the axial direction.

The cylinder hole 3 has a stepped shape in which a valve hole 3A, a small-diameter hole 3B, a medium-diameter hole 3C, and a large-diameter hole 3D are continuous in a direction from the output port 4 to the flange portion 5. A check valve device 6 is provided in the valve hole 3A. A cover member 7 is screwed into the valve hole 3A so as to cover the check valve device 6. A check valve device 6 is provided on the lid member 7.
An inlet port 9 is formed through the hole 8 to communicate with the outlet port of the master cylinder M operated by the brake pedal P. Exit port
4 communicates with the small-diameter hole portion 3B through the hole 10,
It is connected to a wheel cylinder B for operating the wheel brake device.

A driven member 11 and a metal sleeve 12 serving as a detent portion of the driven member 11 are accommodated in the large-diameter hole portion 3D of the cylinder hole 3. Sleeve 12
Has a guide portion 13 on the inner peripheral surface thereof and has a large-diameter hole portion 3D.
The end on the input port 9 side is engaged with the step 3a of the large diameter hole 3D via the annular member 14. The driven member 11 is slidably fitted in the sleeve 12, and the end face on the input port 9 side is in contact with the annular member 14.

Reference numeral 15 denotes a rotating shaft serving as a driving member, which has a flange-shaped portion 16, a large-diameter portion 17, a medium-diameter portion 18, and a small-diameter portion 19 which are successively reduced in the axial direction. Yes,
It is supported by a bearing 20 disposed in the large diameter hole 3D of the cylinder hole 3. In the bearing 20, the inner ring is externally fitted to the large-diameter portion 17 of the driving member 15 and is engaged with the flange portion 16, and the outer ring is press-fitted into the large-diameter hole 3D.

The driven member 11 and the driving member 15 are screwed together by screwing a screw shaft 21 extending from the flange 16 of the driving member 15 toward the input port 9 to the driven member 11. Have been.

Reference numeral 22 denotes a cap having a peripheral wall, and a large hole 23 penetrating in the axial direction is formed at the center of the bottom wall. The cap 22 has the driving member 15 penetrated through the large hole 23 and is screwed to the outer periphery of the main body 2. By rotating and tightening the cap 22, the sleeve 12 and the bearing 20 are joined together with the large diameter hole 3 </ b> D. To the side of the step 3a.

An axial plunger 24 is slidably accommodated in the cylinder bore 3 and extends into the medium bore 3C and the small bore 3B. The plunger 24 is integrally formed with a conical portion 24A that protrudes in the axial direction while reducing the diameter from the one end surface. Divides the pressure chamber A into
The other end surface 24a has a cylindrical shape and extends into the medium-diameter hole portion 3C, and is in contact with the end surface 11b of the driven member 11 on the input port 9 side. In addition, the plunger 24 is
A small shaft portion 24B extending from the front end of the check valve device 6 to the inlet port 9 side passes through a small hole 6a communicating the inside of the check valve device 6 and the pressure chamber A, and the valve body 6B of the check valve device 6 is seated. 6A, the check valve device 6 is normally opened.

In the middle diameter portion 3C of the cylinder hole 3, a stop member 25, a seal member 26 for preventing leakage of hydraulic fluid supplied to the pressure chamber A from the small diameter hole portion 3B side, and a holding member 27 are fitted on the outer periphery of the plunger 24 in this order.

The driving member 15 protruding outside from the cylinder hole 3 includes a clutch portion 28 for restricting the rotation of the driving member 15 and a transmission member 31 for transmitting the rotation of the motor 32 to the driving member 15. Are arranged. Clutch part 28
Is a clutch spring 29 fitted on the outer periphery of the cap 22.
And a clutch plate 30 press-fitted to the outer periphery of the middle diameter portion 18 of the drive member 15 so as to be engageable with the clutch spring 29. The transmission member 31 transmits the rotation of the motor 32 to the drive member 15 via the clutch portion 28, and is rotatably attached to the small diameter portion 19 of the drive member 15.

The motor 32 has a motor main body 33 and an output shaft 34 projecting from the motor main body 33 while reducing its diameter in the axial direction. A pinion gear 35 is externally fitted, a nut is screwed into a screw portion at the end of the output shaft 34, and the nut is rotated and tightened to hold the pinion gear 35 on the output shaft 34. Mo
The motor 32 fits the reduced-diameter stepped portion 33A of the motor main body 32 provided on the side where the output shaft 34 protrudes into the mounting hole 5a of the main body 2 and mounts it on the flange portion 5 of the main body 2. Have been.
At this time, the pinion gear 35 protruding from the flange portion 5
Are meshed with the outer periphery of the transmission member 31. Reference numeral 36 denotes a lid, which is a pinion gear 35 of the transmission member 31 and the motor 32.
And is attached to the flange portion 5 of the main body 2.

Here, FIG. 2 shows that the driven member 11 is
FIG. 3 is a cross-sectional view showing a state in which the sleeve 12 is fitted in the sleeve 12, and the relationship between the driven member 11 and the sleeve 12 will be described in detail below with reference to FIG.

The sleeve 12 has a guide portion 13 formed of a resin having a predetermined thickness on its inner peripheral surface.
The inner surface of the cylinder has a regular hexagon as a base, and at each of the corners, an arcuate surface 13a having a predetermined radius is formed, and is pressed into the large-diameter hole portion 3D of the cylinder hole 3 so as not to rotate. . The driven member 11 is shaped like a nut having a regular hexagon as a base, and each corner is formed with an arc surface 11a that engages with the arc surface 13a of the guide portion 13, respectively.
By engaging each of the arc surfaces 11a with the arc surface 13a of the guide portion 13, the sleeve 12 is fitted into the sleeve 12 so as to be non-rotatable and slidable in the axial direction of the cylinder hole 3.

Next, FIG. 3 (a) is a view showing a state in which the clutch portion 28 and the transmission member 31 are assembled into the drive member 15, and the clutch portion will be described below with reference to FIG. 3 (a). The relationship between 28 and the transmission member 31 will be described in detail.

The coil-shaped clutch spring 29 is fitted around the outer periphery of the cap 22 with a predetermined interference. At both ends of this winding, locking portions 29A which are bent radially outward at a predetermined angle from each other. , 29B.

The clutch plate 30 is formed integrally with fan-shaped portions 30A and 30B projecting radially outward at predetermined intervals on the circumference thereof. The outer circumference of each of the fan-shaped portions 30A and 30B is formed in the axial direction. Protruding convex portions 37A and 37B are provided, respectively, and are press-fitted to the outer periphery of the middle diameter portion 18 of the driving member 15. At this time, the engaging portion 29B of the clutch spring 29 on the lid 36 abuts on the convex portion 37B of the fan-shaped portion 30B of the clutch plate 30.

The transmitting member 31 has a recess 38 having one end opened.
A flange 39 projecting radially outward is integrally formed on the outer periphery of the open end.
Are provided with teeth 40 on the outer peripheral surface thereof.
Notched portions 41A and 41B extending radially outward and in the axial direction at predetermined intervals around the circumference are formed on the inner peripheral wall.
The transmission member 31 is fitted on the outer periphery of the small-diameter portion 19 of the drive mechanism 15 via a bearing, and covers the clutch spring 29 and the clutch plate 30 from the radial outside with the concave portion 38. The notches 41A and 41B are
Of the clutch spring 29 are fitted into the fan-shaped portions 30A and 30B of the clutch spring 29, respectively.
A, 29B are located so as to be able to abut against the respective notches 41A, 41B.

The brake actuator 1 according to the first embodiment of the present invention is constructed as described above. Next, the operation of the brake actuator will be described.

When the brake actuator 1 is not operated, the check valve device 6 is open as shown in FIG. 1, and the drive member 15 is in the state shown in FIG. (In the following, this state is simply called the initial state.)
It has become.

Now, when the brake pedal P is depressed, a hydraulic pressure is generated in the master cylinder M, and this hydraulic pressure flows from the discharge port of the master cylinder M to the input port 9, the pressure chamber A, and the output port. Through the wheel 4 to the wheel cylinder B of the wheel. This usually causes the wheels to brake.

At this time, when the hydraulic pressure supplied from the master cylinder M to the pressure chamber A acts on the plunger 24, the plunger 24 is pressed in a direction to increase the volume of the pressure chamber A. When a force causing a linear movement is transmitted to the driving member 15 via the driven member 11 and the screw shaft portion 21 and a rotational force is applied to the driving member 15, the convex portion 37B of the sector 30A of the clutch plate 30 is moved as shown in FIG. As shown in FIG. 3A, the engaging portion 29B on the lid 36 side of the clutch spring 29
Abut. Then, when further rotational force is applied to the driving member 15, the clutch plate 30 presses the engagement portion 29A to tighten the clutch spring 29, and the frictional force between the clutch spring 29 and the outer peripheral surface of the cap 22 increases, so that the driving member Fifteen
Is stopped, so that the plunger 24 does not move and remains stopped. In this embodiment, since the outer peripheral surface of the cap 22 having a larger diameter than the inner diameter of the cylinder hole 3 is used as the frictional engagement surface of the clutch spring 29, compared with the case where the inner wall of the cylinder hole 3 is used. The rotation stopping force is increased.

The hydraulic pressure of the wheel cylinder B of the wheel rises together with the hydraulic pressure of the master cylinder M. However, if a control unit (not shown) determines that the braking force exceeds an appropriate braking force, for example, the wheel If the rate exceeds the predetermined slip rate, a brake release signal is generated from the control unit, thereby operating the motor 32.

When the motor 32 operates to rotate the output shaft 34, this rotation is transmitted to the transmission member 31 via the pinion gear 35, and the transmission member 31 rotates or turns (hereinafter simply referred to as rotation). ). At this time, the transmission member 31
As shown in FIG. 3 (b), the notch 41A is located on the input port 9 side of the clutch spring 29 from the rotational direction.
A, the inner diameter of the clutch spring 29 is pushed and widened to reduce the frictional force between the clutch spring 29 and the outer peripheral surface of the cap 22, so that the clutch spring 29 rotates together with the transmission member 31.

Then, the notch 41A of the transmission member 31 comes into contact with the projection 37A and the notch 41B comes into contact with the projection 37B from the rotation direction side, and the clutch plate 30 rotates together with the clutch spring 29. Rotation is clutch plate 30
Is transmitted to the drive member 15 through the drive shaft, and the drive member 15 rotates.

When the driving member 15 rotates, the driving member 15
Driven member 1 which is screw-engaged with a screw shaft portion 21 via a screw shaft portion 21
1 is a non-rotatable sleeve 12 and a guide 12
As a result, the rotational force of the driving member 15 is converted into an axial propulsion force, and is separated from the annular member 14 so as to be separated from the annular member 14. Move straight to the side. At this time, the plunger 24 moves from the position in the initial state toward the driving member 15 following the movement of the driven member 11, and finally the valve body 6B of the check valve device 6 is moved. When the user sits on the seat 6A, the supply of the hydraulic fluid from the input port 9 to the pressure chamber A is shut off.

When the driving member 15 further rotates, the plunger 24 moves while increasing the volume of the pressure chamber A, whereby the pressure of the wheel cylinder B communicating with the pressure chamber A decreases. However, the braking force is reduced, and the braking force is set to an appropriate value.

Next, when the control unit determines that the wheel speed has sufficiently recovered, the brake loosening signal is canceled and the pressure of the hydraulic fluid supplied to the wheel cylinder B is increased again. A brake signal is generated from the control unit, and the motor 32 is operated. When the motor operates to rotate the output shaft 34 in the opposite direction (hereinafter simply referred to as reverse rotation), the rotation of the output shaft 34 is transmitted via the pinion gear 35 to the transmission member 3.
1 and the transmission member 31 rotates in the reverse direction. At this time,
As shown in FIG. 3 (c), the transmission member 31 has the notch 41A.
Are located on the input port 9 side of the clutch spring 29.
A, the notch 41B comes into contact with the engaging portion 29B on the cover 36 side of the clutch spring 29, and the inner diameter of the clutch spring 31 is expanded, so that the clutch spring 29 and the cap 2 are separated.
Since the friction force with the outer peripheral surface of the clutch spring 29 is reduced, the clutch spring 29 rotates in the reverse direction together with the transmission member 31.

The notch 41B comes into contact with the convex portion 37B via the engaging portion 29B of the clutch spring 29 and the notch 41A comes into contact with the convex portion 37A from the rotation direction side of the transmission member 31, so that the clutch spring Clutch plate 30 with 29
, And this rotation is transmitted to the driving member 15 via the clutch plate 30, and the driving member 15 rotates.

When the driving member 15 rotates, the screw shaft 21
The driven member 11 which is screw-engaged linearly moves toward the input port 9 side. Then, the plunger 24 is pressed by the driven member 11 and moves toward the input port 9 while reducing the volume of the pressure chamber A, whereby the wheel communicating with the pressure chamber A is thereby formed. -The pressure of the cylinder B increases and the braking force increases.

When it is determined again that the control unit has exceeded the proper braking force, the plunger 24 is moved to the transmission member 31 as described above, and
By reducing the pressure supplied to the cylinder B, the braking force is reduced.

As described above, even if the pressure of the wheel cylinder B repeatedly rises and falls and sudden braking is applied, the wheel can be given an appropriate braking force without being locked. According to such a first embodiment, the driven member 1
Reference numeral 1 denotes a guide portion 1 formed of a resin on the arcuate surface 11a.
By engaging with the arcuate surface 13a of the
Is positioned in the radial direction with respect to
When the cylinder 5 reciprocates in the axial direction of the cylinder hole in accordance with the rotation or rotation of the cylinder 5, the sliding resistance is reduced by the resin of the guide portion 13 without any radial movement, and the axial direction of the cylinder hole 3 is reduced. Can be moved.

Further, since the sleeve 12 having the function of preventing the driven member 15 from rotating and guiding the axial movement of the cylinder hole 3 is formed separately from the main body 2 of the actuator 1, it is conventional. In addition, it is not necessary to perform unevenness processing for complicating the shape such as providing a flange portion and an alignment edge portion in the cylinder hole 3 and the driven member 11.

Further, since the sleeve 12 is made of metal and only the portion for guiding the driven member 11 is made of resin, the fixing force of the cap 22 can be received by a highly rigid metal portion, and The deformation and damage of the guide portion 13 when the sleeve 12 is assembled into the cylinder hole 3 does not occur as compared with the case where the whole 12 is made of resin.

Second Embodiment Hereinafter, a second embodiment of the present invention will be described with reference to FIG.

FIG. 4 shows a brake actuator used in an automatic brake system or traction control. In addition, each member of the reference numeral 100 and thereafter shown in FIG. 4 corresponds to each member in the first embodiment, and a detailed description thereof will be omitted.

In the brake actuator 101 shown in FIG. 4, a driven member 111 having the same configuration as that of the first embodiment is provided in the large diameter hole portion 103D of the cylinder hole 103.
The bus 112 is housed. The sleeve 112 is press-fitted into the large-diameter hole portion 103D, and is pressed together with the bearing 120 toward the step portion 103a by the cap 122. The driven member 111 is, as shown in FIG. 111a is engaged with the sleeve 112 by engaging with the arcuate surface 113a of the guide portion 113. When the master cylinder M is not operated, hydraulic fluid to be automatically supplied to the wheel cylinder B is added. The end face of the driven member 111 on the cap 122 side is in contact with the bearing 120 for pressing.

The plunger 124 is urged toward the cap 122 by maximizing the volume of the pressure chamber A by the return spring 60 disposed in the pressure chamber A, and the end face 124 a of the cap 122 is driven by the driven member 111. Abuts against the end face 111b of the.

In the pressure chamber A, an input port 109 is provided.
An opening / closing valve 70 for opening and closing is provided. This on-off valve 7
Reference numeral 0 denotes a valve seat 70A formed on a surface where the hole 108 opens to the cylinder hole 103, and a valve body 7 that can be attached to and detached from the valve seat 70A.
0B and a spring 70D for urging the valve body 70B in the seating direction together with a rod 70C connected to the valve body 70B.

The rod 70C of the on-off valve 70 extends toward the plunger 124, and its tip is fixed to the end of the plunger 127 on the input port 109 side.
The valve body 70B of the on-off valve 70 is separated from the valve seat 70A by the spring force of the return spring 60 via the spring seat 71 against the urging force of the spring 70D.

The transmission member 131 is press-fitted to the outer periphery of the driving member 115, so that the output shaft 1 when the motor 132 is operated.
The rotation of the motor 34 is transmitted to the driving member 115 directly, that is, without the intervention of the clutch mechanism.

The brake actuator 101 according to the second embodiment of the present invention is configured as described above. Next, the operation of the brake actuator 101 will be described.

When the brake actuator 101 is not operated, as shown in FIG. 4, the input port 109 and the pressure chamber A are in a communication state (hereinafter, this state is simply referred to as an initial state). The working fluid in a non-pressure state is filled from the master cylinder M through the pressure chamber A to the wheel cylinder B.

Now, while the vehicle is running, the inter-vehicle distance to the vehicle in front is detected by a sensor (not shown). A key signal is generated, which causes the motor 132 to operate. When the motor 132 is operated, the output shaft 134 rotates,
This rotation is transmitted to the drive member 115 via the transmission member 131, and the drive member 115 rotates.

When the driving member 115 rotates, the driven member 111 causes the driving member 11 to resist the spring force of the return spring 60.
5 linearly moves from the side of the flange portion 116 toward the side of the input port 109. The plunger 124 is pressed and moved by the movement of the driven member 111, and the valve body 70B is moved by the spring force of the spring 70D.
Side, and finally, the valve body 70B is seated on the valve seat 70A to shut off the input port 109 from the pressure chamber A.

When the drive mechanism 115 further rotates, the plunger 124 moves toward the input port 109 while reducing the volume of the pressure chamber A, so that a hydraulic pressure is generated in the pressure chamber A. The hydraulic pressure is supplied to the wheel cylinder B communicating with the pressure chamber A, and the brake is applied. The hydraulic pressure of the wheel cylinder B is increased or decreased by reciprocating the plunger 124 via the driven member 111 by rotating the motor 132 forward or backward with the on-off valve 70 closed. You.

Thereafter, if the control unit determines that the inter-vehicle distance has recovered to an appropriate distance, the brake signal disappears and the operation of the motor 132 stops. As a result, the output shaft 134 of the motor 132 is brought into a rotatable free state, and the plunger 124 reversely rotates the screw shaft portion 121 and the transmission member 131 via the driven member 111 by the spring force of the return spring 60. Then, the pressure chamber A is moved toward the bearing 20 while increasing the volume of the pressure chamber A, and is returned to the initial state. Therefore, the valve body 70A is separated from the valve seat 70B, and the master cylinder M and the pressure chamber A communicate with each other. Thus, the pressure chamber A is in a non-pressure state. As a result, the hydraulic pressure supplied to the wheel cylinder B is also released, and the brake is released.

Also in the second embodiment, a sleeve 112 inserted into and fixed to the cylinder hole 103 is provided as a detent portion for the driven member 111.
2. Guide part 1 having arcuate surface 113a formed of resin
Since the member 13 is provided, the same operation and effect as those of the first embodiment can be obtained such that the movement of the driven member 111 can be guided without displacement.

[0058]

As described in detail [devised effect of above, according to the present invention of the brake actuator, when the driven member, which reciprocates in response to rotation or pivoting of the drive member, positive polygonal hole
Inside arc surface with apex angle and outside arc surface with apex angle of regular polygonal prism
Is positioned in the radial direction with respect to the cylinder hole by the guide portion that engages with the drive member, so that even if there is some radial play in the screw interposed between the drive member and the screw, there is no radial movement. Since the guide member is guided and moved in the axial direction of the cylinder hole, the displacement of the driven member with respect to the cylinder hole can be prevented, and the smooth movement of the driven member and the plunger interlocking with the driven member can be secured. Thus, an actuator having excellent responsiveness can be obtained. Further, even if the driven member slides with respect to the guide portion, the sliding resistance is reduced by the resin layer, so that the driven member can be moved more smoothly. Also, a set of substantially regular polygons
Non-rotating part and guide with simple configuration
Can be provided, the cylinder hole and the driven part
The concentricity between the material and the screw can be improved, and the operation is circular.
It will be smooth. Furthermore, the apical angles of the substantially polygons are fitted to each other.
, And driven at the portion corresponding to each apex angle
Disperses the force acting on the fitting part by receiving the force from the member
it can. Therefore, the fitting part of the cylinder hole is made of resin etc.
And the processing of the fitting portion is facilitated.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a brake actuator according to a first embodiment of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

FIG. 3 is a sectional view taken along the line YY in FIG. 1, wherein (a) shows the engaged state of the clutch unit and the transmission member when the brake actuator is stationary, and (b) relaxes the pressure of the wheel cylinder. The rotation state of the clutch part and the transmission member at the time,
(c) shows the rotational state of the clutch unit and the transmission member when the pressure of the wheel cylinder is applied.

FIG. 4 is a longitudinal sectional view showing a brake actuator according to a second embodiment of the present invention.

[Explanation of symbols]

 2, 102 Main body 3, 103 Cylinder hole 11, 111 Driven member 12, 112 Sleeving (rotation prevention portion) 13, 113 Guide portion 15, 115 Driving member 21, 121 Screw shaft portion (screw) 24, 124 Plunger 32 , 132 motor (motor)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B60T 17/00 B60T 8/40

Claims (1)

(57) [Scope of request for utility model registration] 1. A main body having a cylinder hole, a drive member extending into the cylinder hole and being rotatable or rotatable by an electric motor, and fitted to the drive member via a screw to reciprocate in the cylinder hole. A movable driven member, a plunger capable of increasing or decreasing the volume of a pressure chamber defined in the cylinder hole in accordance with reciprocation of the driven member, and a detent for preventing rotation of the driven member with respect to the main body. Wherein the detent portion is provided on the driven member of the cylinder hole.
The inner surface of the mating part has a substantially regular polygonal hole shape.
A portion corresponding to the apex angle is formed on the inner arc surface, and
The outer surface of the moving member has a substantially regular polygonal column shape, and its apex angle
Are formed on the outer arc surface and the inner arc surface is formed.
The outer arcuate surface and engage the brake actuator guide portion for slidably guiding and positioning the driven member in a radial direction with respect to the cylinder bore are a configuration that is provided with.