JPH086665Y2 - Hydraulic parking brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic parking brake device provided with a safety mechanism.

[Prior Art] Conventionally, a negative-acting hydraulic parking brake device has been used. This parking brake device is provided with a piston 2 in a hydraulic brake cylinder 1 as shown in FIG. 5, and a friction plate 4 is fixed to a power transmission shaft 5 of the power transmission shaft 5 by a piston 2 which is normally pressed leftward by a spring 3 in the drawing. The braking force is applied by pressing it against the brake disc 6.

The pressure chamber 9 of the hydraulic brake cylinder 1 has a supply / drainage line.
10 is connected, and the operation portion 7 is connected to the liquid supply / drainage line 10.
The hydraulic pressure source 11 and the tank 12 are connected via a main switching valve 8 which is switched by the switching operation of. 20 is a power supply and 21 is a main switch.

In this parking brake device, when the operation unit 7 for releasing the brake and switching the operation is switched to the release side, the main switching valve 8 is switched and the pressure chamber 9 of the hydraulic brake cylinder 1 is switched.
The fluid supply / drainage line 10 connected to the hydraulic pressure source 11 communicates with the hydraulic pressure source 11, and the piston 2 moves to the right against the pressing force of the spring 3 to release the braking force.

Switching the operating part 7 to the operating side The main switching valve is switched, and the supply / drainage line 10 connected to the pressure chamber 9 of the hydraulic brake cylinder 1 communicates with the tank 12 so that the pressure liquid in the pressure chamber 9 is connected. Is discharged, and the piston 2 is moved to the left again by the pressing force of the spring 3 to return to the braking state.

[Problems to be solved by the device]

Such a parking brake device has a braking characteristic as shown in FIG. Where P0 is the pressure of the hydraulic pressure source 11, P1
Is the pressure at which the brake is released and the operation is switched. When the operating portion 7 is switched from the released state to the operating side, the main switching valve 8 is switched, the pressure liquid is discharged, and the pressure P in the pressure chamber 9 is rapidly reduced. When the pressure P reaches P1 from P0 after the time t1, the braking torque T is generated and rapidly increases. Therefore, it is possible to obtain a sufficient braking force capable of stopping the vehicle even on a steep slope with a quick operation.
However, if an accident such as damage to the hydraulic pressure source 11, damage to the solenoid S1 of the main switching valve 8 or poor continuity of the power supply or ground circuit connected to the solenoid S1 occurs while the vehicle is traveling, the driver There is a possibility that a sudden braking action may occur without any prediction, and shocks due to sudden braking during high-speed running are particularly dangerous.

This invention solves the above-mentioned problem in the parking brake of a vehicle, and an object thereof is to provide a hydraulic parking brake device that can stop the vehicle safely even if an accident should occur.

[Means for solving the problem]

This invention proposes an operation part for releasing and operating the brake, and a main switching valve for switching the supply and discharge of the pressure liquid in the supply and discharge pipe of the pressure chamber of the hydraulic brake cylinder by the switching operation of the operation part. A negative-acting hydraulic brake device equipped with a detection unit that detects a release or actuation switching operation in the operation unit and outputs a signal continuously for a predetermined time, and while receiving an output signal from this detection unit. The above problem is solved by only providing a flow rate control valve for reducing the line resistance of the supply / drainage line.

[Action]

In the parking brake device of the present invention, when the operation portion is switched to release and operate, the detection portion detects the switching operation almost at the same time as the main switching valve performs the switching operation and the flow control valve A signal is output to the solenoid, and in response to this, the flow control valve operates in the direction to reduce the line resistance of the supply and drainage line, and this state is released in the hydraulic brake cylinder until the operation or operation is completed. Continued. Therefore, similar to the conventional parking brake device, quick release and actuation operations are performed.

On the other hand, if the parking brake is activated due to an accident despite not performing the switching operation, no signal is output from the detector to the solenoid, and the flow control valve increases the line resistance of the supply / drainage line. Since the operation is performed in the direction of causing the pressure chamber to discharge, the discharge flow rate of the pressure liquid from the pressure chamber is limited, and the pressure in the pressure chamber gradually decreases. Therefore, the generated control torque gradually increases, and the vehicle can be stopped safely without being shocked by sudden braking even when traveling at high speed.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a hydraulic parking brake device according to an embodiment of the present invention. The basic configuration of this device is
Similar to the conventional hydraulic parking brake device shown in the figure, a piston 2 is provided in the hydraulic brake cylinder 1, and the friction plate 4 is constantly pressed by the spring 3 and the friction plate 4 is used as the brake disc of the power transmission shaft 5. 6 is pressed to apply braking force.
Further, in this embodiment, a small spring for pressing the friction plate 4 to the left side of the friction plate 4 to the right side in the drawing with a force weaker than that of the spring 3.
19 are provided.

The pressure chamber 9 of the hydraulic brake cylinder 1 has a supply / drainage line 10
The liquid supply / drainage line 10 is connected to the hydraulic pressure source 11 and the tank 12 via the main switching valve 8 which is switched by the switching operation of the operating portion 7. The main switching valve 8 is a two-position electromagnetic switching valve, and the supply / drainage conduit 10 is normally in communication with the tank 12. The main switching valve 8 is switched when the operating portion 7 is switched to the release side, and the supply / drainage conduit 10 is switched. To the fluid pressure source 11.

A liquid amount control valve 13 is connected in the middle of the liquid supply / drainage line 10. The flow rate control valve 13 is a two-position electromagnetic switching valve, which normally has a throttle in the liquid supply / drainage line 10, and can be switched by a signal from the detection unit 14.

The detection unit 14 includes a detection unit power supply 19, a one-shot multivibrator 15, an output transistor 16, a capacitor C, and a resistor R. When the operation unit 7 performs a release operation or a switching operation to the operating side, the operation signal is , As a UP waveform from “0” to “1” or a DOWN waveform from “1” to “0” at the logic level, is input to the A and B terminals of the one-shot multivibrator 15. The A terminal is an input terminal for up-edge operation and the B terminal is an input terminal for down-edge operation. Here, both terminals are connected to each other so that both up-edge and down-edge operation can be performed.

The one-shot multivibrator 15 outputs "0" from the Q terminal when there is no waveform input to the A and B terminals,
When the UP or DOWN waveform is input to the A and B terminals, "1" is output from the Q terminal for a time t3 determined by the capacitor C and the resistance R from that moment, and then returns to "0". In addition, since this one-shot multivibrator 15 has a re-trigger function, while continuously inputting a waveform with a period shorter than time t3 to the A and B terminals (the operation unit 7 frequently releases and operates). The output of the Q terminal holds "1" during the switching operation).

The output transistor 16 is a non-contact switch section that constitutes a ground circuit of the solenoid S2 only while "1" is being output from the Q terminal and enables energization of the solenoid S2.
Reference numeral 20 is a power supply for the operation unit 7 and the detection unit 14, 21 is a main switch of the vehicle, S1 and S2 are main switching valves 8, and solenoids of the flow control valve 13.

When the operation portion 7 is switched from the operating side to the releasing side, the solenoid S1 is energized, and the main switching valve 8 is switched to the position connecting the supply / drainage liquid pipeline 10 and the hydraulic pressure source 11 almost at the same time. The UP waveform is input to the A and B terminals of the multivibrator 15, a base current flows from the Q terminal to the output transistor 16, the solenoid S2 is energized, and the flow control valve 13 is switched to a position where the line resistance is reduced. Therefore, when the brake is released, the same operation as the conventional one is performed. However, in the initial release until the reaction force of the small spring 19 disappears,
A slight braking force comes into play. After releasing the brake (time t3 after switching the operating portion 7 to the releasing side), the flow control valve 13 is switched to a position where the conduit resistance is increased, and this state is maintained until the operating portion 7 is operated next time. Keep

When the operating portion 7 is switched from the release side to the operating side, the solenoid S1 is de-energized, and the main switching valve 8 is closed.
Almost at the same time as switching to the position where 10 and tank 12 are connected, D at the A and B terminals of one-shot multivibrator 15
OWN waveform is input and output transistor 16 from Q terminal
A base current flows through the solenoid S2, and the solenoid S2 is energized to switch the flow control valve 13 to a position where the line resistance is reduced. The control torque characteristic in this case is as shown in FIG. 3, which is almost the same as the conventional characteristic shown in FIG. However, small spring 19
Since the return of the piston 2 becomes slightly gradual due to the reaction force of, the rising of the braking torque T is somewhat gradual.
It should be noted that the flow control valve 13 is switched to a position where the conduit resistance is increased after the brake is actuated (time t3 after the operation section 7 is switched to the operation side), and this is maintained until the operation section 7 is operated next. Keep the state.

When the pressure chamber 9 and the tank 12 are connected in an accident while the vehicle is traveling with the operation unit 7 in the release position,
Since the flow control valve 13 is in the position to increase the line resistance,
The outflow rate of the pressure liquid from the pressure chamber is slow, and the pressure in the pressure chamber gradually decreases. Therefore, as shown in FIG. 4, time t2
The braking torque generated later gradually increases, and the vehicle stops safely without shock.

The operation status of the solenoids S1 and S2 according to the operation guidance of the operation unit 7 is shown in the timing chart of FIG.

This safety mechanism consisting of the detection unit 14 and the flow control valve 13 has a structure in which an accident occurs in the safety mechanism itself and the flow control valve 13
It is designed on the safe side so that the brake operation speed will be delayed if the brake does not operate.

[Effect of device]

According to the present invention, the operation speed during normal parking brake operation is not delayed, and in the event that the parking brake is activated due to an accident during traveling, the vehicle can be stopped safely without giving a shock. .

[Brief description of drawings]

FIG. 1 is a configuration diagram of a hydraulic parking brake according to an embodiment of the present invention, FIG. 2 is a timing chart showing operating conditions, FIG. 3 is a characteristic curve diagram at the time of normal operation, and FIG. FIG. 5 is a characteristic curve diagram during operation due to an accident, FIG. 5 is a configuration diagram of a conventional hydraulic parking brake, and FIG. 6 is a characteristic curve diagram during operation. 1 ... Hydraulic brake cylinder, 2 ... Piston, 3 ...
Spring, 4 ... Friction plate, 5 ... Power transmission shaft, 6 ...
Brake disc, 7 ... Operating part, 8 ... Main switching valve, 9 ...
Pressure chamber, 10 ... Supply / drain line, 11 ... Fluid pressure source, 12 ... Tank, 13 ... Flow control valve, 14 ... Detection section.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. An operation section for releasing and operating the brake, and a switching operation of the operation section for switching the supply and discharge of the pressure liquid in the supply and discharge pipe line connected to the pressure chamber of the hydraulic brake cylinder. A negatively actuated hydraulic brake device including a main switching valve, the detection unit detecting a brake release or actuation switching operation in the operation unit and continuously outputting a signal for a predetermined time, and the detection unit. And a flow rate control valve for reducing the conduit resistance of the supply / drainage conduit only while receiving an output signal from the hydraulic parking brake device.