JPH0450218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an improvement of a spring chamber type parking brake device for an industrial vehicle, and more particularly to a parking brake device incorporating a deadman function.

[Prior Art] As shown in FIG. 2, in a spring chamber type parking brake device conventionally used in industrial vehicles, pressurized air is supplied to a tank 2 by a compressor 1 operated by an engine (not shown) or the like. When the pressurized air is stored and fed into the spring chamber 4 by operating the parking switch 3, the pressure air causes the spring chamber 4 to be
The rod 5 moves in the direction of the arrow against the urging force of the spring disposed therein, and the parking brake 8 is released via the turnbuckle 6 and the connecting rod 7. On the other hand, when the pressure air in the spring chamber 4 is exhausted by operating the parking switch 3 in the opposite direction, the rod 5 moves in the opposite direction of the arrow due to the biasing force of the spring, and the rod 5 is moved through the turnbuckle 6 and the connecting rod 7. The parking brake 8 is configured to be actuated by the parking brake 8. In addition,
Reference numeral 9 denotes a limit switch as a brake detector, and when the pressure air is exhausted and the parking brake 8 is activated by the biasing force of the spring, due to a failure factor of connecting elements such as the connecting rod 7,
If the rod 5 over-moves without the parking brake 8 being fully activated, a lever 10 working together with the rod 5 turns on the limit switch 9 and lights up the warning lamp 11.

[Problems to be Solved by the Invention] However, with the conventional device described above, the parking brake cannot be activated unless the driver operates the parking switch. There is a built-in danger that this could lead to self-propulsion, which could lead to a serious accident.

The present invention aims to solve the technical problem of incorporating a dead man function into the parking brake device.

[Means for Solving the Problems] An electromagnetic switching valve for operating and releasing the parking brake is provided in the pneumatic pipeline communicating the spring chamber and the pressure air source, and the electromagnetic switching valve is for circuit maintenance. It is energized by a forward/reverse lever limit switch and a starter switch, which have relays in parallel, to conduct the above pneumatic pipe, and is demagnetized by opening of the starter switch, and connects the pneumatic pipe to the spring chamber with the exhaust system. ,
It uses a so-called dead man mechanism.

[Function] Therefore, when starting the vehicle, following the closing of the starter switch, the forward/reverse shift lever in the neutral state is operated to either forward or reverse.
At the same time, the electromagnetic switching valve is energized when the limit switch for the reverse lever is closed, and the parking brake is released by switching the circuit and supplying pressurized air into the spring chamber. Thereafter, the released state of the parking brake is maintained regardless of the operation of the forward/reverse shift lever by the circuit holding relay which is closed at the same time.

On the other hand, when parking, the circuit holding relay is simultaneously opened when the starter switch is opened, so the electromagnetic switching valve is demagnetized and the circuit is switched again without requiring the operation of a dedicated switch, and the pressure air inside the spring chamber is The parking brake is activated by exhausting the air.

[Example] Hereinafter, an example of the present invention will be described based on the drawings. Note that, except for the dead man mechanism, which is a feature of the present invention, there is no difference in the original mechanism of the spring chamber type parking brake device from that shown in FIG. A detailed explanation will be omitted.

In FIG. 1, an electromagnetic switching valve 21 is disposed on a pneumatic pipe 20 that communicates the tank 2 and the spring chamber 4, and the solenoid of the electromagnetic switching valve 21 is connected to the M terminal of a starter switch 22 and a circuit 23. A forward lever limit switch 24, a reverse lever limit switch 25, and a circuit holding relay 26 are connected in parallel to the circuit 23, which are opened and closed in conjunction with the operation of a forward/reverse shift lever (not shown). And solenoid switching valve 2
1 is switched to the a position when the solenoid is energized to conduct the pneumatic pipe 20, and when the solenoid is demagnetized it is switched to the b position to connect the pneumatic pipe 20a to the spring chamber 4 as an exhaust system. It is configured to be electrically conductive. In addition, 27 is a circuit protection diode for absorbing surge voltage,
28 is a power battery.

The present invention is configured as described above, and when the vehicle is in a resting state, electricity is cut off and the solenoid is demagnetized, so the electromagnetic switching valve 21 is switched to position b as shown in the figure, and the spring chain is switched to position b as shown in the figure. The pressurized air in the chamber 4 is released to the exhaust system through the electromagnetic switching valve 21, and no resistance is acting on the spring (not shown) in the spring chamber 4. Therefore, due to the biasing force of the spring, the rod 5 moves in the opposite direction of the arrow together with the turnbuckle 6 and the connecting rod 7, and the parking brake 8 is placed in an operating state.

When starting the vehicle, first turn on starter switch 2.
However, since the forward/reverse shift lever is in the neutral state at this time, the parking brake 8 still maintains its operating state.
When the forward/reverse shift lever is operated either forward or backward to drive the vehicle after starting, the limit switch 24 for the forward lever or the limit switch 25 for reverse is closed and the circuit 23 is energized.
As the solenoid is energized, the electromagnetic switching valve 21 is switched from the b position to the a position, so the pressurized air in the tank 2 is fed into the spring chamber 4 through the connected pneumatic pipe 20. . Therefore, the pressurized air moves the rod 5 in the direction of the arrow against the biasing force of the spring, and releases the parking brake 8 via the interlocking turnbuckle 6 and connecting rod 7. This driveable state, that is, the excitation of the solenoid by energizing the circuit 23, is maintained by the circuit holding relay 26, which closes in synchronization with the closing of the forward lever limit switch 24 or the reverse lever limit switch 25. This state persists regardless of the operation of the forward/reverse shift lever.

When the starter switch 22 is opened to cut off the power to the circuit 23 in order to park the vehicle,
At the same time, the circuit holding relay 26 is also opened and the solenoid is demagnetized, so the electromagnetic switching valve 21 is turned on again.
The pressurized air in the spring chamber 4 is released to the exhaust system, and the parking brake 8 is again activated.

[Effects of the Invention] As detailed above, since the present invention incorporates a dead-man mechanism into a spring chamber type parking brake device for an industrial vehicle, the driver does not need to operate a parking switch as in the conventional case. Moreover, this has the excellent effect of completely freeing the vehicle from self-driving accidents caused by forgetting to operate the switch.

Moreover, in addition to closing the starter switch, the parking brake is released only when the driver operates the forward/reverse shift lever with the intention of driving, which is particularly useful for ensuring safety when starting on a slope. Demonstrates an effect that is hard to miss.

[Brief explanation of drawings]

FIG. 1 is a mechanical diagram of a parking brake device schematically showing an embodiment of the present invention together with a control circuit;
FIG. 2 is a schematic diagram of a conventional parking brake device. 2...Tank, 4...Spring chamber, 5
... Rod, 8... Parking brake, 20...
... Pneumatic pipe line, 21 ... Solenoid switching valve, 22 ... Starter switch, 24 ... Limit switch for forward lever, 25 ... Limit switch for reverse lever,
26...Circuit holding relay.

Claims (1)

[Claims] 1. In a spring chamber type parking brake device for an industrial vehicle in which the parking brake is actuated via a connecting member by the biasing force of a spring by exhausting pressurized air fed into the spring chamber, the spring chamber An electromagnetic switching valve for operating and releasing the parking brake is provided in the pneumatic pipeline that communicates between the bar and the pressure air source. An industrial vehicle characterized in that the pneumatic pipe is energized by a switch to conduct the pneumatic pipe, and is demagnetized by opening of the starter switch, and the pneumatic pipe connected to the spring chamber is connected to the exhaust system. Parking brake device.