JPH09137842A - Brake device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake device suitable for intelligent operation of the braking function and suitable for miniaturization of the device. SOLUTION: An electric actuator 4 to advance/retract a friction material 3 to/from a rotary body 2 for braking consists of a magnetostrictive material 12 which is of rod-shape in which one end is abutted on the friction material 3 and the other end is locked by a friction material supporting member 10, and whose length is changed in the axial direction by the magnetostriction, and an electromagnetic coil 14 which is fixed to the friction material supporting member 10 to surround the outer circumference of the magnetostrictive material 12 and applies the magnetic field according to the applied voltage. Advancement/ retraction of the friction material 3 necessary for the braking is performed by elongation/contraction due to the magnetostriction of the magnetostrictive material 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric brake device used for braking a vehicle.

[0002]

2. Description of the Related Art A brake device used in a vehicle and driven by hydraulic pressure has a problem in that the number of constituent parts is increased and the structure is complicated due to the hydraulic piping equipment and the hydraulic pressure adjusting mechanism. In recent years, intelligent brake functions such as anti-lock brake system and traction control system have been actively developed. In this case, it is necessary to add an electro-hydraulic control circuit for converting a predetermined electric signal into a mechanical operation of the hydraulic actuator according to the locked state or the slipped state of the wheel. As a result, the control system becomes complicated, or the servo effect, which is a feature of the mechanism, affects the brake control, making it difficult to perform more detailed brake control. .

[0003] Against this background, in recent years,
An electric brake device that generates a predetermined braking force by using a rotary motor as the drive source and pressing a frictional material against a rotary body for braking via a rotation-linear conversion mechanism, a speed reduction mechanism, and the like Japanese Patent Application Laid-Open No. Sho 64-21329) and an electric brake device using piezoelectric ceramics as a drive source (see Japanese Patent Application Laid-Open No. 60-136629) have been proposed.

[0004]

As described above, in the electric brake device utilizing the rotary motor and the piezoelectric ceramics as the drive source, the intelligent brake function such as the anti-lock brake system and the traction control system is provided. Is easier to plan.

However, in a brake device that uses a rotary motor as a drive source, there is a problem that the brake device becomes large due to the equipment such as a rotation-linear conversion mechanism and a speed reduction mechanism. On the other hand, in a brake device that uses piezoelectric ceramics as a drive source, the linear motion required for the forward / backward movement of the friction material can be directly obtained from the drive source, and it is not necessary to use a rotation-linear conversion mechanism or a reduction mechanism. Although it is possible to reduce the size of the brake device, there is a problem that the piezoelectric ceramic has a small amount of displacement and thus has a low ability to allow wear of the friction material. Further, since a device for generating a large voltage is required, there is a problem that the in-vehicle capability is low.

The present invention has been made in view of the above situation, and it is easy to intelligentize the brake function such as the equipment of the anti-lock brake system and the equipment of the traction control system, and it is possible to adapt to the downsizing of the device. An object of the present invention is to provide a brake device capable of setting a large amount of displacement for moving a friction material forward and backward.

[0007]

SUMMARY OF THE INVENTION To achieve the above object, a brake device according to the present invention is provided with a friction material support member that supports a rotating body so as to be capable of advancing and retracting, and the rotating body with the friction material. An electric actuator that moves the friction material forward and backward toward the rotating body to obtain a braking force by pressing, and a control unit that controls the operation of the actuator according to the operation state of the brake operation unit, The actuator is a rod-shaped magnetostrictive material, one end of which is in contact with the friction material and the other end of which is locked by the friction material support member and whose length is changed by magnetostriction when a magnetic field is applied, and an outer periphery of the magnetostrictive material. An electromagnetic coil fixed to the friction material supporting member so as to be located on the side, and applying a magnetic field according to an applied voltage to the magnetostrictive material. Outputs in accordance with an applied voltage of Le to the operating state of the brake operating unit, forward and backward movement of the friction material required braking characterized by being performed by expansion and contraction due to magnetostriction of the magnetostrictive material.

According to the above configuration of the present invention, the rod-shaped magnetostrictive material that expands and contracts due to magnetostriction is used as a drive source for advancing and retracting the friction material toward the rotating body for braking. The linear motion required for the above can be obtained directly from the magnetostrictive material which is the drive source, and the brake device can be miniaturized because it is not necessary to use a rotation-linear conversion mechanism or a reduction mechanism.

Further, since the operation of the magnetostrictive material can be directly controlled by the applied voltage of the electromagnetic coil arranged on the outer peripheral side of the magnetostrictive material, the braking function of the anti-lock brake system equipment or the traction control system equipment can be improved. Easy to make intelligent. The amount of expansion / contraction of the magnetostrictive material can be easily increased by increasing the electric field applied to the magnetostrictive material, that is, by increasing the voltage applied to the electromagnetic coil.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a brake device according to the present invention will be described below in detail with reference to the drawings.
FIG. 1 is a sectional view of an essential part of a brake device according to the present invention.
This brake device is provided as a magnetostrictive brake device 1 applicable to a disc brake for a vehicle, and a pad 3 that is a friction material is pressed against a brake disc (rotor) 2 that is a rotating body for braking to obtain a braking force. An electric actuator 4 for moving the pad 3 forward and backward toward the brake disc 2, and a control unit (ECU) 8 for controlling the operation of the actuator 4 according to the operating state of a brake pedal 6 which is a brake operating section. It is configured with.

The pad 3 is the brake disc 2
A pair of brake calipers 10, which are friction material support members, are provided to sandwich the brake disc 2
It is supported so that it can move back and forth. The actuator 4 has a rod shape, and one end (the left end in the drawing) of the actuator 4 abuts on the pad 3 and the other end thereof is the brake caliper 10.
The magnetostrictive material 12 whose length is changed in the axial direction by the magnetostriction when locked by the magnetic field applied to the magnetostrictive material 12, and fixed to the brake caliper 10 so as to be located on the outer peripheral side of the magnetostrictive material 12 and applied to the applied voltage. And a substantially cylindrical electromagnetic coil 14 for applying a corresponding magnetic field to the magnetostrictive material 12. Further, when the brake pedal 6 is stepped on by the driver,
At that time, the stroke or pedal force depressed is notified to the control unit 8 by a known sensor 16.

The control unit 8 controls the operation of the actuator 4 by detecting a braking command from the driver based on a signal from the sensor 16. In the case of this embodiment, the control unit 8 outputs the signal from the sensor 16. The voltage applied to the electromagnetic coil 14 is controlled according to the signal of. That is, in the magnetostrictive brake device 1 having the above-described configuration, the rod-shaped magnetostrictive material 12 that expands and contracts due to magnetostriction is used as a drive source for advancing and retracting the pad 3 toward the brake disc 2. Since such a linear motion can be obtained directly from the magnetostrictive material 12 which is a drive source, and the rotation-linear conversion mechanism, the speed reduction mechanism, etc. are not used, the brake device 1 can be downsized.

Further, the expansion and contraction of the magnetostrictive material 12 causes the magnetostrictive material 1 to expand and contract.
It can be controlled by the voltage applied to the electromagnetic coil 14 that surrounds the outer circumference of 2, and the control unit 8 can directly control it electrically, so that the intelligent brake functions such as the anti-lock brake system and the traction control system are provided. Easy to plan.

Further, the amount of expansion / contraction of the magnetostrictive material 12 can be easily increased by increasing the electric field applied to the magnetostrictive material 12, that is, by increasing the voltage applied to the electromagnetic coil 14, which is the same as in the case of piezoelectric ceramics. By comparison, the amount of displacement for moving the pad 3 forward and backward can be increased, and the ability to allow wear of the pad 3 can also be increased. The brake device according to the present invention is not limited to the disc brake shown in the above embodiment,
For example, it can be applied to a drum brake.

[0015]

As described above, according to the brake device of the present invention, the rod-shaped magnetostrictive material which expands and contracts due to magnetostriction,
Since the friction material was used as a drive source for advancing and retreating toward the rotating body for braking, the linear motion required for the advancing and retreating motion of the friction material can be directly obtained from the magnetostrictive material, and the rotation-linear conversion mechanism or reduction mechanism The brake device can be miniaturized because it is not necessary to use the above. Further, since the expansion and contraction of the magnetostrictive material can be electrically controlled directly by the applied voltage of the electromagnetic coil surrounding the outer circumference of the magnetostrictive material, intelligent brake functions such as anti-lock brake system equipment and traction control system equipment can be achieved. easy.
Furthermore, the amount of expansion and contraction in the magnetostrictive material can be easily increased by increasing the electric field applied to the magnetostrictive material, that is, by increasing the voltage applied to the electromagnetic coil. The amount of displacement for advancing and retreating can be increased, and the ability to allow wear of the friction material can also be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of a brake device according to the present invention.

[Explanation of symbols]

 1 Magnetostrictive Brake Device 2 Brake Disc (Rotating Body for Braking) 3 Pad (Friction Material) 4 Actuator 6 Brake Pedal 8 Control Unit (ECU) 10 Brake Caliper (Friction Material Support Member) 12 Magnetostrictive Material 14 Electromagnetic Coil 16 Sensor

Claims (1)

[Claims] 1. A friction material support member that is supported so as to be capable of advancing and retreating toward a rotating body, and the friction material is moved forward and backward toward the rotating body to obtain a braking force by pressing the friction material against the rotating body. And a control unit that controls the operation of the actuator according to the operating state of the brake operating unit. The actuator is rod-shaped and has one end in contact with the friction material and the other end. Is locked to the friction material support member and its length changes by magnetostriction when a magnetic field is applied, and a magnetostrictive material fixed to the friction material support member so as to be located on the outer peripheral side of the magnetostrictive material according to an applied voltage. An electromagnetic coil that applies a magnetic field to the magnetostrictive material, the control unit outputs a voltage applied to the electromagnetic coil according to an operating state of the brake operating unit, and A braking device characterized in that the necessary forward and backward movement of the friction material is performed by expansion and contraction of the magnetostrictive material due to magnetostriction.