JPH0352377B2 - - Google Patents

Abstract

PURPOSE:To produce proper braking force reliably by burying the gap between a friction pad and a disc with a wheel cylinder while functioning a piezo ceramic when the liquid pressure has exceeded over predetermined level to produce the braking force. CONSTITUTION:Upon stepping of a brake pedal 10, a wheel cylinder 6 will function to press a friction pad 2 to the disc 1 side thus to bury the pad gap. Upon exceeding of brake liquid pressure over the limit level, a controller 27 will function a solenoid valve 24 through a pressure sensor 26 to close a bypath 25 thus to fix an auxiliary cylinder 23. The controller 27 will apply voltage onto a piezo ceramics 20 to produce braking force corresponding with the detection signal of pressure sensor 26 thus to pressure contact the pad 2 against the disc 1 through a lever 21.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a brake device that skillfully utilizes the actuator function of piezoelectric ceramics as an actuation mechanism for obtaining braking force.

[Prior art]

In so-called braking devices, which are used to control the speed and stop motion of automobiles,
The most common types of brakes are known as drum brakes and disc brakes. The latter type of disc brake obtains braking force by pressing a friction pad material from the side against a disc-shaped disc as a braked member, and the braking force is stable and has a stable force with little variation. Drum brakes are expected to have good distribution, have excellent heat resistance, etc., are easy to install automatic adjustment devices for friction pad material wear, generate little noise, and are easy to deal with. It has an effect that cannot be achieved with other methods, and its popularity has become remarkable in recent years.

By the way, in the above-mentioned brake device, the operating mechanism on the input side generally employs a hydraulic cylinder system that uses fluid pressure such as oil pressure (or air pressure) as a force transmission means, and when the brake pedal is depressed. It is constructed so that the friction pad material can be moved forward and backward relative to the disk etc. in accordance with the operation. In such a hydraulic actuation mechanism, there is a limit to the braking force that can be obtained from pedal depression alone, so a booster consisting of a master cylinder and a servo unit is often used. However, according to the brake device using the above-mentioned hydraulic actuation mechanism, the master cylinder, booster, wheel cylinder,
In particular, in recent years, there has been an increasing demand for diversification of brake control, including anti-skid devices, in this type of brake system. If only the pressure type is used, a valve for controlling the hydraulic pressure is required, and the structure is complicated, which not only limits its practical application, but also cannot guarantee accurate control. It is hoped that some kind of countermeasure will be taken.

For this reason, as the operating mechanism of the above-mentioned brake device, one using an electric motor, a slurry clutch, etc. is disclosed in Japanese Patent Application Laid-Open No. 56-31532, and one using an electromagnetic brake is disclosed in Japanese Patent Application Publication No. 1988-31532.
It has already been proposed in Publication No. 501585, and has the advantage of being electrically actuated compared to the conventional mechanical type, which allows for quick and appropriate braking force and diversification in control. It is something that plays.

However, according to the brake device using the above-mentioned electric actuation mechanism, although the wiring from the brake pedal is simplified, the main body of the actuation mechanism facing the disk etc. becomes large and its configuration is multiple. This not only leads to high costs, but also consumes a large amount of power, and it cannot be said that fine braking force control can be performed appropriately, so there is still room for improvement.

[Summary of the invention]

The present invention has been made in view of the above-mentioned circumstances, and is directed to a hydraulic cylinder for obtaining operating force.
With a simple structure that skillfully combines piezoelectric ceramics that function as actuators by applying voltage, appropriate and reliable braking force can be obtained, and complex brake control that is desired to be diversified can be easily performed. The purpose of the present invention is to provide an inexpensive brake device that can be operated appropriately, and also allows the entire device to be simplified, smaller and lighter.

〔Example〕

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

FIG. 1 shows an embodiment in which a brake device according to the present invention is applied to a single cylinder type disc brake. In the same figure, first, the general structure of the whole will be briefly explained. Reference numeral 1 is a disc as a braked member that rotates together with a wheel (not shown), and 2 and 3 are selectively pressed against both sides of the disc to sandwich it. Friction pads serve as friction members that provide braking force, and 2a and 3a are butt plates attached to the outer surfaces of the pads. Reference numeral 4 denotes a carrier body disposed so as to straddle above both of these friction pads 2 and 3. This carrier body 4 is formed in a substantially U-shape so as to straddle the disk 1, and is attached to a support bracket 5 serving as a fixed part. This is a so-called floating type in which the disc 1 is slidably supported in a direction perpendicular to the surface of the disc 1.

A cylinder hole 6a constituting a wheel cylinder 6 is formed on one side of the above-mentioned caliper body 4 in a portion facing the back surface of one of the friction pads 2. A piston 7 is fitted into the cylinder hole 6a, and the tip of the rod 7a of the piston 7 is configured to abut against the pad plate 2a and press it toward the disk 1. Note that 4a and 4b (one not shown) in the figure are claws provided on the other side of the carrier body 4 and facing the back side of the other friction pad 3, and are used to connect the carrier body 4 operated by the wheel cylinder 6. It acts to press the friction pad 3 of the lever against the disk 1. Furthermore, 8 is a seal ring that seals between the piston 7 and the cylinder hole 6a and provides a return habit to the piston 7, and 9 is a boot.

Further, in the rear side chamber of the piston 7, a pipe 12 is disposed to guide hydraulic pressure from a master cylinder 11 that generates a desired hydraulic pressure when the brake pedal 10 is depressed.

Now, according to the present invention, in the above-described configuration, a braking piezoelectric ceramic 20 is disposed on one side of the caliper body 4 in parallel with the wheel cylinder 6, and its thrust is applied to the friction via the pressing lever 21. It is unique in that the braking force is transmitted to the pad 2 and brought into pressure contact with the disc 1 to obtain doubled braking force.

To explain this in detail, an auxiliary cylinder hole 22a is formed in one side of the carrier body 4 in parallel with the cylinder hole 6a, and a piston 23 that holds the rear end of the braking piezoelectric ceramic 20 slides inside the auxiliary cylinder hole 22a. freely supported. The hydraulic pressure bypassed from the hydraulic pressure piping 12 is guided to the bottom chamber of the auxiliary cylinder 22 constructed thereby through a bypass passage 25 having a solenoid valve 24. This solenoid valve 24 is controlled by a controller 27 in response to a signal from a pressure sensor 26 that detects the hydraulic pressure on the upstream side of the bypass path 25 that increases due to the pedal operation, and when the hydraulic pressure rises above a specified value. The bypass path 25 is operated to close only when the bypass path 25 is closed, and to keep it open at all times.

In addition, in the figure, 28 is a pusher provided at the tip of the piezoelectric ceramic 20, 29 is a bracket provided on the carrier body 4, and has a support shaft 29a for pivotally supporting the lever 21 pressed by the pusher 28.
22b is a sealing ring, and the lever 21
The tip of the piston rod 7a of the wheel cylinder 6 is connected to the piston rod 7a of the wheel cylinder 6 via a support shaft 21a.

The piezoelectric ceramic 20 described above, together with the electromagnetic valve 24, is controlled by a controller 27 using a control circuit as shown in FIG.

To explain this simply, the controller 27 is provided with comparators 30 and 31 that compare the input signal from the pressure sensor 26 with a specified value, and one of the comparators 30 is connected to the drive circuit 32 that controls the solenoid valve 24. The other comparator 31 is connected to the pressure sensor 2.
It is connected to a switch 34 connected to an amplifier 33 that amplifies the input signal from 6, and is configured to turn it on and off. When the switch 34 is turned on, the drive circuit 35 operates the piezoelectric ceramic 20.

Here, the piezoelectric ceramic 20 described above can expand and contract in its length direction by applying a voltage and function as an actuator. For example, the piezoelectric ceramic 20 can function as an actuator. Formed as a body. And for example its length is 20mm, area
30mm ² , when applying a voltage of 200V, the thrust is 500
Kg, displacement is about 0.01mm (2 when applying positive and negative voltages)
It has been confirmed that it is possible to obtain double the amount of

According to the above-described configuration, when the brake pedal 10 is depressed, the wheel cylinder 6 is actuated, and the piston rod 7a and the lever 2 are operated.
1 to press the friction pad 2 toward the disk 1 to fill the gap between the pads, and the pressure sensor 26
When the hydraulic pressure detected by the pressure sensor exceeds a specified value, the solenoid valve 24 operates to close the bypass passage 25, fix the piston 23, and at the same time obtain a braking force according to the detection signal from the pressure sensor 26. A voltage is applied to the piezoelectric ceramic 20, and the pad 2 is brought into pressure contact with the disk 1 via the lever 21 by its thrust.

Furthermore, after the pedal 10 is released, it is necessary to provide an appropriate gap between the disc 1 and the pad 2, but this is easily understood as each cylinder 6, 22 returns to its non-operating state due to a drop in hydraulic pressure. It will be.

Therefore, as described above, the structure in which the braking force is obtained using the piezoelectric ceramics 20 in addition to the hydraulic wheel cylinder 6 makes it possible to achieve a simple and inexpensive structure, and to reduce the overall size and weight. Regardless of the situation, a quick and appropriate braking force can be obtained by pressing the brake pedal, and various brake controls such as anti-skid and pump braking can be easily performed by adjusting the control signal from the controller 27. It is something. The piezoelectric ceramic 20 described above has the advantage of low power consumption, low heat generation, low noise, and the like. Furthermore, by adopting such a configuration, the braking force can be doubled compared to the conventional hydraulic type only, and the entire device can be simplified.

Note that the present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each part may be modified or changed as appropriate.

For example, in the above-mentioned embodiment, a case was explained in which the device of the present invention is applied to a single cylinder type disc brake, but the present invention is not limited thereto. It will be easily understood that the present invention can be applied to various types of braking devices including the opposed cylinder type disc brake obtained by this method.

〔Effect of the invention〕

As explained above, according to the brake device according to the present invention, a piezoelectric ceramic that functions as an actuator by applying a voltage is used as a hydraulic cylinder as an actuating body that obtains braking force by bringing a friction member into pressure contact with a braked member. Although it is a simple and inexpensive structure, it is possible to quickly and appropriately obtain braking force according to pedal operation and to demonstrate its performance. In addition to doubling the power, it also makes it possible to easily and appropriately carry out various types of brake control, such as anti-skid, which are troublesome and require diversification, and it also simplifies the entire device and makes it smaller and lighter. There are various excellent effects that can be achieved.

[Brief explanation of drawings]

The figures show one embodiment of a brake device according to the present invention, with FIG. 1 being a schematic diagram of the entire configuration, and FIG. 2 being a control circuit diagram thereof. 1... Disc (braked member), 2, 3... Friction pad (friction member), 4... Caliper body,
6... Hydraulic wheel cylinder, 7... Piston, 10... Brake pedal, 12... Hydraulic pressure piping, 20... Piezoelectric ceramics for braking, 21...
Pressure lever, 22... Auxiliary cylinder, 24... Solenoid valve, 25... Bypass path, 26... Pressure sensor, 27... Controller.

Claims (1)

[Claims] 1.Equipped with an actuation mechanism that obtains braking force by pressing a friction member against a braked member, and this actuation mechanism includes a hydraulic cylinder that is actuated by hydraulic pressure generated by pressing the brake pedal and presses the friction member. , and a braking piezoelectric ceramic that applies pressure contact force to the friction member, which is arranged in parallel with the friction member, and the rear end of the piezoelectric ceramic opens and closes according to the pressure in the hydraulic pressure supply path to the hydraulic cylinder. A brake device characterized in that the brake device is held in a piston of an auxiliary cylinder connected to the hydraulic pressure supply path via a solenoid valve.