JPH10194108A - Electromechanical brake actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the electromechanical brake actuator to make braking force control compatible with responsiveness, and to put the brake actuator to practical use as an actuator of a tread type braking device. SOLUTION: This electromechanical brake actuator 1 is provided with a ball screw mechanism B, a main spring 10, a sub-spring 11, and a ball screw shaft driving device (electric motor 5, etc.) as main components, and the main spring 10 and the sub-spring 11 are arranged coaxially with a ball screw shaft 6 of the ball screw mechanism and in series with each other so that the spring tension of the main spring 10 acts on the ball screw shaft 6. Thus, the braking force is outputted on the basis of variable spring force of the sub-spring 11, which is obtained when the ball screw shaft 6 is driven-rotated to displace the main spring 10 and stop it at an optional position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromechanical brake actuator for pressurizing and releasing a vehicle brake device.

[0002]

2. Description of the Related Art Conventionally, as a vehicle brake device, a device which is mainly pressurized by air pressure has been put to practical use. In general, there are two types of brake devices: a disk type that frictionally brakes a disk attached to an axle, and a tread type that frictionally brakes a peripheral surface of a wheel. Since various devices are mixed around the brake device, the devices must be compact. Particularly in the case of a tread-type brake device, there is a strong demand for compactness. Heretofore, there has been no practical example in which an electromechanical brake actuator is used as a driving means of a tread type brake device.

FIG. 5 shows a conventional air-pressed tread-type brake device 50. In this method, the force of the air pressure pressing the piston 51 is transmitted to the push rod 53 via the operating lever 52 having the rotation fulcrum 52a, and the brake shoe 54 is pressed against the wheel 55. By adopting the link mechanism by the operating lever 52,
The actuator body A is attached to the bogie frame 56 to
By allowing the brake shoe 54 to be pressed toward the center of the lever 5 and utilizing the leverage of the operating lever 52, the force required by the actuator is reduced.

[0004] However, although the brake device 50 is a sophisticated device, since it uses air pressure, large devices such as an air compressor, an air reservoir, and an air pipe (not shown) are required for use on a vehicle. There was a problem that required and quick response could not be obtained.

Therefore, in order to solve such a problem,
Early attempts have been made to create a simple and responsive brake device that directly uses electricity, the most common energy for vehicles. The trick in this case is how to keep the vehicle safe when electricity is not available.
In the event of a power failure, a method is used in which the brake shoes are pressed against the wheels by spring force.

[0006] Proposals for these electromechanical brake devices are disclosed in US Patent Nos. 3,217,843 and 3,28.
No. 0,944, No. 3,693,759, No. 3,69
No. 8,520, 4,202,530, British Patent Nos. 4,033,435, 2,141,500, European Patents 0,166,156 and 0,334,434. .

Many of these methods employ a method of changing the output torque of a DC motor to output a difference from a spring force as a braking force as a braking force control method.
That is, since the current value of the electric motor is set according to the required braking force and a predetermined braking force is obtained as a result, the controllability of the braking force is not good. According to the teachings of a DC motor textbook, when the output torque is changed according to the current value, the rotation speed is also determined at the same time.
If priority is given to the force (torque) control, the number of revolutions is sacrificed, and there is an example in which low responsiveness becomes a problem, and an example in which an impact problem occurs when the motor is stopped instantaneously from a high speed. Therefore, some have tried to solve these problems by including a cushion spring. Another part operates two springs with two electric motors to obtain a controlled braking force as a difference between the spring forces, but this complicates the machine. There were disadvantages.

Referring to FIG. 6, US Pat. No. 4,033,435 will be described as an example of the structure closest to the present invention. The main components of the brake actuator 100 according to this patent are a motor 101, a pinion 102 provided on a motor shaft, a gear 103 provided on an intermediate shaft, a pinion 104, and a ball screw shaft 10.
5, a ball nut 107 attached to a ball screw shaft 105 via a ball (not shown), a hub 108 keyed to the ball nut 107, and assembled around the hub 108. Multiple disc springs 10
9 In FIG. 6, the component on the right side of the motor 101 is a mechanism for manual operation at the time of a power failure, and 110 connected to the hub 108 is a slack adjuster, and is not directly related to the present invention.

The operation of the apparatus 100 is as follows. First, when the brake is released, the rotation of the rotation shaft of the motor 101 is decelerated by the gears 102, 103, 104, and 106 and transmitted to the ball screw shaft 105, and is converted into a rightward motion by the ball nut 107. 109 is compressed. Flange 111 of hub 108
Is moved by a predetermined distance, the microswitch 112 is switched to the ON state, and in response to this, the drive voltage of the motor 101 is reduced to a voltage that maintains the spring force and is maintained.

When the brake is pressed, the motor 101
Is further reduced. Accordingly, since the force of the disc spring 109 exceeds the holding force of the motor 101, the disc spring 109 pushes the collar 113 (see FIG. 6), and the braking force is applied to the brake device 115 via the slack adjuster 110 and the clevis 114. Is transmitted.

[0011]

However, the conventional brake actuator as described above has the following problems. That is, the first problem of the electromechanical brake actuator according to the above-mentioned patent is that there is only a current control method as described above as a control method of the braking force, and it is difficult to achieve both the braking force control and the responsiveness. .

A second problem is that the conventional electromechanical brake actuator can output only a pressing force and cannot obtain a pulling force. As can be seen from FIG. 5, when the tread-type brake device is operated by using the operating lever 52, it is necessary to pull the tip 52 b of the operating lever 52 in the direction opposite to the wheel 55. However, this is not possible with the electromechanical brake actuator according to the above-mentioned patent. The reason is that if an attempt is made to adopt a configuration in which this electromechanical brake actuator is used in place of the piston 51 of the device of FIG. This is because such an arrangement space cannot be secured above the wheel 55.

In order to apply this actuator to a tread type brake device, it is necessary to adopt a configuration in which the output shaft of the actuator is arranged on the center line of the wheel 55 and the wheel 55 is directly pressed. Requires a fairly large pushing force. In addition, a large frame is required to suspend such an actuator from the bogie frame 56 to the center line of the wheels 55. All of these points are not suitable for tread-type brakes that require compactness.

As described above, in the electromechanical brake actuator having the conventional structure, the control of the braking force and the responsiveness are not compatible with each other, and the current situation is that the actuator cannot sufficiently meet the needs of the user. Furthermore, in the case of the conventional actuator for an electromechanical brake having a conventional structure, it cannot be applied to the tread type because the study of compactness is insufficient.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and an object of the present invention is to achieve both a braking force control and a responsiveness, and to be used as an actuator of a tread type brake device. An object of the present invention is to provide such an electromechanical brake actuator.

[0016]

According to the present invention, there is provided an electromechanical system including a ball screw mechanism, a main spring, a sub-spring, and a ball screw shaft driving device as main components. A brake actuator, wherein the main spring and the sub spring are arranged coaxially with a ball screw shaft of the ball screw mechanism and in series with each other, so that a spring force of the main spring acts on the ball screw shaft. Then, a braking force is output based on a variable spring force of the sub-spring obtained when the main spring is displaced by a rotational drive of the ball screw shaft and stopped at an arbitrary position.

Further, in the present invention, one end of the operating lever having a pivot point is connected to the sub-spring, and the tread surface braking force is output via the operating lever by the spring force of the sub-spring.

That is, the present invention employs a so-called double spring configuration in which a main spring for final pressurization and an auxiliary spring for brake force control are arranged in series with each other, and the displacement of the main spring is stopped at an arbitrary position. By making the auxiliary spring force output,
The brake force can be controlled. Various methods are conceivable for stopping the main spring at an arbitrary position. In a preferred embodiment, for example, a method of controlling the rotation of a servomotor that drives a ball screw is adopted.

Further, according to the present invention, in order to apply the present invention to a tread-type brake device, the output direction of the spring force is devised so that a link similar to that of a pneumatic system in practical use can be used, and the required force can be reduced. It is easy to reduce and arrange the equipment, and it is possible to use it on a tread.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIGS.

First, FIG. 1 shows a tread-type brake device 2 provided with an electromechanical brake actuator 1 according to a first embodiment of the present invention. Actuator for mechanical brake 1
And a brake mechanism 3 operated by the actuator 1. The above-described electromechanical brake actuator 1 includes, as shown in FIG. 1, a housing (casing) 4, an electric motor (servo motor) 5 fixed to the housing 4 in a state of being fitted into the housing 4, and A ball screw shaft (main shaft) 6 composed of a rotating shaft of the electric motor 5 and having a part of the axial direction processed for a ball screw, and a ball screw processing part of the ball screw shaft 6 via a ball (not shown). The ball nut 7 is fitted so as to be relatively movable, a spring biasing mechanism 8 disposed in relation to the ball nut 7, and an operating lever 9 for taking out an actuator output. Thus, the ball screw mechanism B is constituted by the ball screw shaft 6 and the ball nut 7, and the ball nut 7 is linearly moved along the ball screw shaft 6 by driving the rotation of the ball screw shaft 6.

The above-described spring urging mechanism 8 includes a main spring 10,
The auxiliary spring 11, the sleeve 12, the sleeve end flange 13, and the auxiliary spring retainer 14 are combined. More specifically, the sleeve 12 has a spring stopper 12a on the outer peripheral side of an intermediate portion in the longitudinal direction,
A ball (not shown) or the like is fixed to the outside of the ball nut 7 and slidably disposed on the outer peripheral surface of the ball screw shaft 6 by the bearing 15. Further, a sleeve end flange 13 is fixed to one end side of the sleeve 12 (the side of the electric motor 5), and an auxiliary spring presser 14 is provided on the outer periphery of the sleeve 12 in a region between the sleeve end flange 13 and the spring stopper 12a. Are slidably fitted along the axis. A plurality of disc springs 1 are provided between the spring stopper 12a of the sleeve 12 and the inner end face 4a of the housing 4.
A main spring 10 made of 6a is mounted, and one end of the main spring 10 is engaged with the inner end face 4a, and the other end is engaged with a spring stopper 12a. Further, the spring stopper 12a
A sub-spring 11 composed of a plurality of disc springs 16b is mounted between the sub-spring presser 14 and one end of the sub-spring 11 which is engaged with the spring stopper 12a and the other end of which is engaged with the sub-spring retainer 14. Is being worn.

In this embodiment, the main spring 10 is arranged coaxially with the sleeve 12 at a position opposite to the electric motor 5 with respect to the spring stopper 12a, and the auxiliary spring 11 is connected to the spring stopper 12a. It is arranged coaxially with the sleeve 12 at a position closer to the electric motor 5 side. Further, the sleeve 12 and the sleeve end flange 13 integrally assembled with each other are slidably disposed along the axial direction of the ball screw shaft 6.

One end of the actuator output take-out operating lever 9 is connected to the auxiliary spring presser 14 and the sleeve end flange 1.
3 and the outer peripheral surface of the sleeve 12, and is connected to the ball screw shaft 6 so as to be rotatable relative to the ball screw shaft 6 to form a lever operating end 9a. As a result, the lever operating end 9a is assembled so as to be movable relative to the ball screw shaft 6 as described later,
In addition, they are connected so that the output of the actuator can be transmitted to the operation lever 9. The rotation fulcrum (lever fulcrum) 9b of the intermediate portion of the operating lever 9 is
And a lever rotating end 9c at the other end is connected to a push rod 20 of the brake mechanism 3.

Thus, at the position opposite to the electric motor 5 with respect to the lever operating end 9a, the main spring 10 and the auxiliary spring 11 are coaxially assembled with the sleeve 12 and, consequently, the ball screw shaft 6 and in series with each other. The spring force of the main spring 10 is configured to act on the ball screw shaft 6 via the sleeve 12, the ball nut 7, and the like.

On the other hand, the brake mechanism 3 includes a push rod 20 to which the lever operating end 9c is connected, a brake lining 21 to which an operating force is transmitted from the push rod 20, and a brake attached to the brake lining 21. The shoe 22 includes a shoe 22 and a rotating lever 23 rotatably mounted between the housing 4 and the brake lining 21 to rotatably support the brake shoe 22. In FIG. 1, reference numeral 24 denotes wheels to be braked by the brake shoes 22.

In addition, an electromagnetic brake 25 is provided on the ball screw shaft 6. Further, although not shown, sensors such as a brake force detection sensor and a main shaft rotation angle detection sensor are incorporated as sensors.

Next, the operation principle of the tread-type brake device 2 having the above-described configuration will be described together with the operation principle of the electromechanical brake actuator 1 with reference to FIGS.

In the actuator 1 of this embodiment, FIG.
Since the main spring 10 and the sub-spring 11 are arranged as shown in FIG. 5, the main spring 10 cannot perform the positioning of the sub-spring 11 and the action of the final pressurization, and the control of the sub-spring 11 during a power failure. The sub-spring 17 acts to output the control force, with the action of full pressurization at the time. This operation will be described in detail below.

The displacement (rotation) of the ball screw shaft 6 and the main spring 1
FIG. 1 shows the relationship between the displacement spring force of the auxiliary spring 11 and the braking force.
Referring to FIG. 2 and FIG.
The displacement end of the main spring 10 connected to the
L with the rotation of the screw shaft 6 ₁To L_ThreeDisplaced until
Ne is F₁To F_ThreeChange between. This main spring 10
The most extended and the spring length is L_ThreeSpring force F when_ThreeTo
The maximum brake multiplied by the lever ratio of the operating lever 9
Force P_ThreeIt is. Main spring 10 and operating lever via each member
9, the main spring 10 is the most extended.
Longer spring length is L_ThreeThe lever operating end 9a
Spring retainer 14 and spring 12 fixed to sleeve 12
Spring length l between the_ThreeCompressed. So
Then, in this state, the ball screw shaft 6 is rotationally driven.
The ball nut 7 is moved to the left in FIG.
Accordingly, the main spring 10 is contracted, and accordingly the largest spring
Length l_TwoAnd thereafter shown in FIG. 2 (B).
This spring length l_TwoExtension limit (without spring force)
Limited).

Here, regarding the braking force control, the main spring 1
The case where the actuator is operated in the direction in which 0 extends (rightward in FIG. 1) will be described again. In a section of the displacement of the main spring 10 (spring length) from L ₁ to L _2, the locking between the spring stopper portion 12a and the sub-spring retainer 14 in the sub-spring 11 the absence of the spring force is fully extended No braking force is generated.

Next, when the displacement of the main spring 10 becomes L ₂ , the auxiliary spring 11 comes into contact with the lever operating end 9 a via the auxiliary spring retainer 14 to generate a spring force f ₂ , and the brake multiplied by the lever ratio is applied. outputting a force P ₂ (FIG. 2 (a), the reference (B)). As the main spring 10 further extends, the auxiliary spring 11 starts to be compressed by the reaction force received from the lever operating end 9a, and the spring force of the auxiliary spring 11 increases. When the displacement of the main spring 10 is in the L _3, sub spring 11 the brake force P ₃ which is determined by the spring force F ₃ of the main spring 10 is fully compressed almost becomes the output.

[0033] Thus, the braking force is stopped at any point in the interval of the spindle displacement n ₂ ~n ₃ corresponding to the rotation amount from the adjustable ball screw shaft 6 a reference position between the P ₂ of P ₃ Then, a braking force corresponding to the spring force of the sub-spring 11 at that point is obtained. Rotation amount n _{1 of} main shaft 10
n ₂ is a separation operation section for separating the brake shoe 22 from the sliding surface of the wheel 24. As the motor operation,
From said n ₁ after high speed rotation to around n _2, if the deceleration in terms of n _2, it is possible to achieve the realization of a low impact and stop position accuracy and responsiveness.

Here, the specific operation of the tread type brake device 2 of this embodiment will be described as follows. First, when the brake is released, the electric motor 5 moves the ball screw shaft 6 to the main spring 1.
0 is rotated in the direction of compression (the rotation direction in which the ball nut 7 is moved to the left in FIG. 1), and the sensor (not shown) detects detachment of the brake shoe 22 (rotation amount n ₂ ). After rotating a predetermined number of rotations until the rotation amount n ₁ is reached, the rotation driving is stopped. In synchronization with this, the electromagnetic brake 25 operates to keep the ball screw shaft 6 in a non-rotatable state. At this time, since there is no force acting on the sub-spring 11, the sub-spring 11 is extended to the full stroke, the sleeve end flange 13 abuts on the lever operating end 9a and pulls it, and the brake shoe 22 is separated from the wheel 24. . This state is the brake release state shown in FIG.

At the time of pressurizing the brake, first, the electromagnetic brake 2
5 is stopped, and the ball screw shaft 6 is in a free rotation state. The motor 5 initially rotates at a high speed, and the ball screw shaft 6 is separated from each other (a section between n _{1 and} n ₂ in FIG. 2B).
Immediately before reaching the above-mentioned n ₂ , whereby the impact when the auxiliary spring presser 14 hits the lever operating end 9 a is relieved, and the ball nut 7 and thus the operating lever 9
To easily set the stop position. An initial braking force is generated by the rotation amount (rotation position) n ₂ of the ball screw shaft 6, and the auxiliary spring 11 is compressed as the sleeve 12 moves rightward in FIG. The braking force increases. When the sensor (not shown) detects that the braking force has reached a predetermined value, or when the ball screw shaft 6 reaches a preset number of revolutions, the drive of the electric motor 5 is stopped and the electromagnetic brake 25 is turned off. It operates to hold the ball screw shaft 6 in a non-rotatable state. This state is a brake pressurizing state (brake operating state).

At the time of a power failure, the excitation of the electromagnetic brake 25 is cut off and the ball screw shaft 6 becomes free to rotate.
The ball screw shaft 6 is forcibly rotated about its axis by the spring force of (1), and the brake shoe 22 is moved toward the wheel 24 in response to this, and is pressed under pressure. This state is an emergency braking state, a fail-safe state, or a forced braking state.

FIG. 3 shows a tread-type brake device 30 provided with an electromechanical brake actuator 29 according to a second embodiment of the present invention. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals.

In this embodiment, as shown in FIG. 3, the electric motor 5 and the ball screw shaft 6 are arranged in parallel in the upper and lower stages, and the rotational driving force of the electric motor 5 is transmitted through the reduction gear mechanism 31 to the ball screw shaft. 6 is transmitted. The rotation drive end of the ball screw shaft 6 by the electric motor 5 is an end opposite to that of the first embodiment described above. An end member 32 having a cylindrical portion 32a and a flange portion 32b is fitted to an end of the sleeve 12 to which the ball nut 7 is fixed, that is, an end on the wheel 24 side.
A spring stopper member 33 is fixed to the end face of the second. The auxiliary spring retainer 14 is slidably disposed along the cylindrical portion 32a of the end member 32 between the spring stopper member 33 and the flange portion 32b of the end member 32.

Next, the arrangement of the main spring 10 and the auxiliary spring 11 will be described as follows. That is, the main spring 10
Is fixed to a locking ring 34 provided on a housing portion corresponding to an intermediate portion of the sleeve 12 in the axial direction to form a spring fixing portion. And the main spring 1
The other end of 0 is engaged with a spring stopper 12b provided at the other end of the sleeve 12, and serves as a spring displacement end.
On the other hand, one end of the sub-spring 11 is engaged with the spring stopper 33 to be a spring fixed end, and the other end is engaged with the sub-spring retainer 14 to be a spring displacement end. Thus, the main spring 10 and the sub-spring 11 are disposed at both left and right portions of the flange portion 32b, and the main spring 10 is connected to the wheel 24 with respect to the lever operation end 9a of the actuator output take-out operation lever 9. The auxiliary spring 11 is disposed on the side of the wheel 24 with respect to the lever operating end 9a.

On the other hand, the lever operating end 9a is
4 and the flange portion 32 b of the end member 32, and is disposed so as to be movable relative to the ball nut 7. The other configuration is the same as that of the first embodiment described above, and the description is omitted.

The tread-type brake device 30 having such a configuration is described.
According to this, the same operation as in the case of the above-described first embodiment can be performed. That is, when the brake is released, the ball nut 7 is arranged on the left side in FIG. 3, and the lever operating end 9a is drawn by the flange portion 32b of the end member 32, whereby the brake shoe 22 is moved to the wheel 2
4 is located at a position separated from the reference numeral 4. When the brake is pressurized, the auxiliary spring retainer 14 comes into contact with the lever operating end 9a as the ball nut 7 is moved to the right in FIG. 1, and thereafter, the stop position of the ball nut 7 and the main spring 10 The spring force of the auxiliary spring 11 corresponding to the displacement position (an arbitrary controllable displacement position) is transmitted to the operating lever 9 via the auxiliary spring retainer 14, and the brake shoe 22 is pressed against the wheel 24. Therefore, also in this case, the braking action is performed by the spring force of the auxiliary spring 11. On the other hand, at the time of a power failure, the operating lever 9 and the brake shoe 22 are moved back by the spring force of the main spring 10 to forcibly enter the brake pressurized state.

Accordingly, the tread-type brake device 30 of the second embodiment can provide the same operation and effect as those of the brake device 2 of the first embodiment.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made based on the technical concept of the present invention. For example, in the above-described embodiment, the electric motor 5 composed of a servomotor is used as the main shaft driving means. However, instead of this, another type of electric motor, furthermore, an air motor or a hydraulic motor can be used. Alternatively, screws and nuts such as trapezoidal screws can be used. The rotary drive shaft of the electric motor 5 and the ball screw shaft 6 are the first drive shaft shown in FIG.
It is not necessary to be integral as in the case of the embodiment, but may be connected by a joint or the like. It is also possible to reduce the speed of the ball screw shaft 6 with the intermediary of the connecting mechanism. In the above-described first and second embodiments, the main spring 10 and the sub spring 11 are replaced by a plurality of disc springs 16a,
16b, coil springs can be used as these springs.

Further, in the case of the first embodiment, the fixed end and the displaced end of the main spring 10 are reversed so that a pressing force can be obtained at the end of the main shaft, so that the present invention can be easily applied to a disc brake. Conceivable.

[0045]

As described above, according to the present invention, an electromechanical brake actuator that achieves both braking force control and responsiveness for the first time by the double spring configuration of the main spring and the sub-spring and the main spring position control is provided. It became possible to provide. Further, by the actuation lever built-in system of the present invention, the required force is reduced and the arrangement is facilitated, and it is possible to provide an electromechanical brake actuator suitable for application to a tread type brake device for the first time. became. As a result, it is possible to replace the pneumatic actuator for the tread-type brake device, thereby reducing the total equipment for the brake (compacting), improving responsiveness and maintainability, and at the same time, saving energy and labor. Is also big.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a tread-type brake device including an electromechanical brake actuator according to a first embodiment of the present invention.

2A and 2B are diagrams for explaining a relationship between a spring force and a braking force when the electromechanical brake actuator of FIG. 1 is used, and FIG. 2A illustrates a relationship between a spring force and a main shaft displacement (amount of rotation); (B) is a characteristic diagram showing a relationship between a spring displacement amount on the main shaft and a main shaft displacement (rotation amount).

FIG. 3 is a cross-sectional view illustrating a configuration of a tread-type brake device including an electromechanical brake actuator according to a second embodiment of the present invention.

4 is a cross-sectional view showing an operation state of the electromechanical brake actuator of FIG. 3 when a brake is pressed.

FIG. 5 is a cross-sectional view showing a configuration of a conventional pneumatic tread brake.

FIG. 6 is a cross-sectional view showing a configuration of a conventional electromechanical brake actuator.

[Explanation of symbols]

 1,29 Electromechanical brake actuator 2,30 Tread type brake device 3 Brake mechanism 5 Electric motor (servo motor) 6 Ball screw shaft (Main shaft) 7 Ball nut 8 Energizing mechanism 9 Operating lever 9a Lever operating end 9b Lever Support point 9c Lever rotation end 10 Main spring 11 Sub spring 12 Sleeve 12a, 12b Spring stopper 13 Sleeve end flange 14 Sub spring retainer 16a, 16b Disc spring 22 Brake shoe 24 Wheel 25 Electromagnetic brake 31 Reduction gear mechanism 32 End member 32a Cylindrical part 32b Flange part 33 Spring stopper B Ball screw mechanism

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isao Nakata 5007 Itozakicho, Mihara City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd.

Claims (2)

[Claims] An electromechanical brake actuator comprising a ball screw mechanism, a main spring, a sub spring, and a ball screw shaft drive as main components, wherein the main spring and the sub spring are connected to the ball screw. It is arranged coaxially with the ball screw shaft of the mechanism and in series with each other so that the spring force of the main spring acts on the ball screw shaft, and the main spring is displaced by the rotation drive of the ball screw shaft. An actuator for an electromechanical brake, wherein a braking force is output based on a variable spring force of the sub-spring obtained when stopping at an arbitrary position. 2. An end of an operating lever having a rotation fulcrum is connected to the auxiliary spring, and a tread surface braking force is output via the operating lever by a spring force of the auxiliary spring. Item 2. An electromechanical brake actuator according to item 1.