JPH0641902Y2 - Work vehicle brake display - Google Patents

Description

[Detailed description of the device]

[0001]

[Industrial field of application] This invention is a work for confirming a state in which a working vehicle such as a wheel type hydraulic shovel equipped with a traveling brake by pneumatic pressure or hydraulic pressure, a crane vehicle or the like is performing a braking function. The present invention relates to a vehicle brake display device.

[0002]

2. Description of the Related Art A conventional brake display device of this type is shown in FIG.
~ Shown in FIG. The compressed air source 1 includes a compressor 1b operated by the engine 1a, a check valve 1c, an air tank 1d, and a relief valve 1e. The air tank 1d is connected to the respective input ports of the brake pedal valve 2 for stepping and the manual brake switching valve 3, and the output port of the brake valve 2 for traveling is connected to the input port of the manual brake switching valve 3. ing.

The output port of the brake switching valve 3 is connected to the main braking device 4 and the parking braking device 5.
The brake switching valve 3 has a switching lever 6 as shown in FIG.
Is operated to switch between neutral (N position), parking (P position), and working (W position). The N position and the W position are the N position detection limit switch 7
And W position detection limit switch 8, respectively. When the lever 6 is in the N position, the N position detection limit switch 7 is opened, and when it is in the W position, the
The position detection limit switch 8 is closed. Also, FIG.
As shown in, the input terminals of these limit switches 7 and 8 are connected to the power source 9, the output terminal of the N position detection limit switch 7 is grounded through the parking brake operation indicator light 10, and the W position detection limit switch 8 is connected. The output terminal of is connected to the ground via the main brake operation indicator lamp 11.

When the lever 6 is at the N position, the N position detection limit switch 7 and the W position detection limit switch 8
Is released, and the parking brake operation indicator light 10 and the main brake operation indicator light 11 are turned off. When the lever 6 is in the P position,
Since the N position detection limit switch 7 is closed and the W position detection limit switch 8 is opened, the parking brake operation indicator light 10 is turned on and the main brake operation indicator light 11 is turned off. When the lever 6 is in the W position, both the N position detection limit switch 7 and the W position detection limit switch 8 are closed, and the parking brake operation indicator light 10 and the main brake operation indicator light 11 are both turned on. In the conventional device, it is possible to visually confirm whether or not the braking function of each brake is performed in this way.

[0005]

However, the above-mentioned conventional brake indicating lamp has the following problems. The parking brake operation indicator light 10 and the main brake operation indicator light 11 are
Since the light is turned on or off depending on the position of the lever 6 regardless of the pneumatic circuit that operates the main braking device 4 and the parking brake device 5, even if the pneumatic circuit fails for some reason, it is displayed according to the position of the lever 6. Lights 10 and 11 are turned on or off. For this reason, the operator visually confirms that the parking brake operation indicator light 10 or the main brake operation indicator light 11 is turned on, and the brake device operates, even though the pneumatic circuit fails and the braking function is not fulfilled. You may park or work as a thing.

Therefore, if the pressure switch is used to turn on and off the indicator lamp as disclosed in Japanese Utility Model Laid-Open No. 188566/1982, the above problem is solved. In this case, in FIG. 5, the brake switching valve 3
A pressure switch is provided in each of the pipeline between the main brake device 4 and the brake switching valve 3 and the pipeline between the brake switching valve 3 and the parking brake device 5, and the indicator lights 10 and 11 are turned on when the pressure switch is opened or closed. It will be composed. However, since pressure is generated in the pipeline between the brake switching valve 3 and the main brake device 4 not only during operation but also during operation of the brake valve 2, operating the brake valve 2 during operation The main brake indicator light 11 is turned on, which gives a very confusing display warning for the driver.

An object of the present invention is to turn on the main brake indicator light when the work brake circuit is formed and the brake device is in the operating state, and to activate the main brake device when the traveling brake circuit is formed. It is to provide a brake display device for a work vehicle in which the main brake indicator light is not turned on even if there is.

[0008]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described with reference to FIG. 1 which is an embodiment. The present invention is a brake provided between a pressure source and a main braking device and between a pressure source and a parking braking device. The present invention is applied to a brake display device of a work vehicle that forms a brake circuit that releases both brake devices during traveling by a switching operation of a switching valve, operates the parking brake device during parking, and operates both brake devices during work. Then, when the operating state of the main brake device is detected and the operating state of the parking brake device is detected, the main brake indicator light is turned on, and even if the operating state of the main brake device is detected, When the operating state is not detected, the main brake indicator light is turned off to achieve the above object.

[0009]

When the work brake circuit is formed in which both the parking brake device and the main brake device operate, the main brake indicator light is turned on. When the main brake pressure is applied when the parking brake device is not operating, that is, when the main brake circuit is formed, the main brake indicator lamp does not light even if the main brake pressure is applied. That is, depending on the operating state of the parking brake device, the main brake indicator light is turned on during work and the main brake indicator light is turned off during traveling.

[0010]

EXAMPLES First Example A first example will be described with reference to FIGS. 1 and 2. The compressed air source 21 that sends out compressed air is configured by connecting the delivery side of a compressor 21b operated by the engine 21a to an air tank 21d via a check valve 21c. Further, a relief valve 21e for keeping the internal pressure of the air tank 21d constant is provided. One input line 22a connected to the air tank 21d is connected to the input port of the traveling brake valve 23, and the other input line 22b is connected to one input port of the brake switching valve 24. Further, the output port of the traveling brake valve 23 is connected to the other input port of the brake switching valve 24.
The traveling brake valve 23 outputs a pressure corresponding to the depression amount of the petal 23a to the output port, and when the petal 23a is released, the output port communicates with the atmospheric port 23b. Further, the brake switching valve 24 is switched to each of the neutral (N), parking (P) and working (W) positions by operating the lever 24a. The brake switching valve 24 is also provided with an exhaust port 24b.

One output port of the brake switching valve 24 is connected to a negative type parking brake device 25 by a line 29, and the other output port is connected to a positive type main brake device 26 by a line 30. There is. In addition, a pipeline that connects the traveling brake valve 23 and the brake switching valve 24 to each other.
27 bypasses the brake switching valve 24 and is connected to the main braking device 26 via the check valve 28 to allow the pressure air from the traveling brake valve 23 to flow directly to the main braking device 26. The pipeline 30 connected to the main braking device 26 is connected to the input port of the pneumatic-hydraulic pressure conversion booster 26a, and its output port is connected to the brake cylinders 26b of the plurality of wheels 31.
The brake is applied when the brake shoe 26c presses the brake drum 26d by the brake cylinder 26b. 26e is a return spring.

A pipeline 29 connected to the parking brake device 25
Is connected to the input port of the pneumatic-hydraulic conversion booster 25a, and its piston rod 25b is connected to the brake shoe 25d via the brake lever 25c. The brake shoe 25d presses the brake drum 25e to apply the brake. Further, a return spring 25f is loosely inserted in the piston rod 25b, and the restoring force of the return spring 25f is constantly urged in the direction of applying the parking brake.

A main brake pressure switch as a main brake pressure detector is closed in the line 30 by a predetermined line pressure.
32 is provided, and the pipeline 29 is provided with a parking brake pressure switch 33 as a parking brake pressure detector that is closed by a predetermined pipeline pressure.

As shown in FIG. 2, the input terminal of the parking brake pressure switch 33 is connected to the power source 34, and the output terminal is connected to the exciting coil 35a of the relay 35. Also relay
The input terminal of the relay switch 35b which constitutes 35 is connected to the power supply 34, and the output terminal is connected to the input terminal of the main brake pressure switch 32 and the parking brake indicator lamp 37 connected in parallel with the main brake pressure switch 32. Has been done. The output terminal of the main brake pressure switch 32 is grounded via the main brake display lamp 36.

In the embodiment having the above structure, when the brake switching valve 24 is operated to the parking position P, a parking brake circuit is formed, when it is operated to the neutral position N, a traveling brake circuit is formed, and when it is operated to the working position W, the work brake is formed. A circuit is formed.

Next, the operation will be described. During operation of the engine 21a, compressed air of a predetermined pressure is constantly stored in the air tank 21d by the compressor 21b, and compressed air is sent from the compressed air source 21. When traveling, the brake switching valve 24 is switched to the N position. At this time, air is introduced into the input port of the pneumatic-hydraulic conversion booster 25a, which causes the piston rod 25 to move.
The parking brake is released via b. On the other hand, since the input port of the pneumatic-hydraulic pressure booster 26a of the main brake device 26 is open to the atmosphere, the restoring force of the return spring 26e does not act on the brake cylinder 26b to release the main brake. It Further, since the parking brake pressure switch 33 is closed and the relay switch 35b is opened, the main brake display lamp 36 and the parking brake display lamp 37 are turned off.

Here, when the petal 23a is stepped on during traveling, air of a predetermined pressure passes through the brake switching valve 24 and reaches the main braking device 26. As a result, pneumatic-hydraulic conversion booster
The hydraulic pressure boosted by 26 acts on the brake cylinder 26b to apply the main brake. At this time, the pressure switch 32 is closed but the display lamp 36 is not lit. When the foot is removed from the petal 23b and the traveling brake valve 23 is turned off, the high-pressure air in the pipeline 30 is opened to the atmosphere via the brake switching valve 24, the pipeline 27, and the brake valve 23. As a result, the hydraulic force does not act on the brake cylinder 26 due to the restoring force of the return spring 26e, and the main brake is released.

When the work vehicle is parked, the brake switching valve 24 is switched to the P position. In this case, the pipeline 29 communicating with the parking brake device 25 communicates with the atmosphere via the brake switching valve 24. Therefore, the piston rod 25b moves upward due to the restoring force of the return spring 25f, and the parking brake is applied. Further, at this time, since the parking brake pressure switch 33 is opened and the relay switch 35b is closed, the power supply 34 and the parking brake display lamp 37 are electrically connected to each other and the parking brake display lamp 37 is turned on. On the other hand, since high pressure air is not sent to the main brake device 26, the main brake device 26 does not operate, the main brake pressure switch 32 is open, and the main brake display lamp 36 is turned off.

When the work vehicle is used for work, the brake switching valve 24 is switched to the W position. In this case, the pipeline 29 communicating with the parking brake device 25 communicates with the atmosphere via the brake switching valve 24, and The pipeline 22b and the pipeline 30 communicate with each other via the brake switching valve 24. Therefore, the parking brake device 25 and the main brake device 26 operate and both brakes are applied. At this time, the main brake pressure switch 32 is closed,
Since the parking brake pressure switch 33 is opened, the main brake display lamp 36 and the parking brake display lamp 37 are turned on.

-Second Embodiment- A second embodiment will be described with reference to FIGS. 3 and 4. In these figures, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. The pipe 29 is provided with a normally closed parking brake pressure switch 39 that opens when a predetermined pressure is reached. Further, the pipe 30 is provided with a normally open type main brake pressure switch 32 that closes when a predetermined pressure is reached, as in the previous embodiment. And
As shown in FIG. 4, these main brake pressure switches 32
And the parking brake pressure switch 39 input terminals are connected in parallel to the power supply 34. The output terminal of the main brake pressure switch 32 is connected to the relay switch 35b of the relay 35, and the output terminal of the parking brake pressure switch 39 is connected to the exciting coil 35a of the relay 35 and the parking brake display lamp 37. The output terminal of the relay switch 35b is connected to the main brake display lamp 36.

When the brake switching valve 24 is in the N position, the pressure in the conduit 29 opens the parking brake pressure switch 39 to turn off the parking brake display lamp 37, and the relay coil 35a is demagnetized to cause the relay switch 35b. Is released and the main brake display lamp 36 is also turned off. When the brake switching valve 24 is in the P position, the pressure in the conduit 29 becomes low and the parking brake pressure switch 39 is closed, so that the parking brake display lamp 37 is turned on. Also the relay coil
Since 35a is excited, the relay switch 35b is closed as shown. However, in this case, the main brake pressure switch 32 remains open, so the main brake indicator lamp 36 is off. It lights up when the brake valve 23 is turned on. When the brake switching valve 24 is in the W position, the main brake pressure switch 32 and the parking brake pressure switch 39
Therefore, both the main brake display lamp 36 and the parking brake display lamp 37 are turned on.

The two brakes 25 and 26 may be controlled by hydraulic pressure instead of pneumatic control. Further, in the above, each pressure switch is directly inserted into the lighting control circuit, but the formation of each brake circuit is discriminated based on the signal from each pressure switch, and each brake indicator light is turned on / off according to the discrimination result. It may be done. In this case, the pressure switch may be composed of a pressure sensor. Furthermore, the brake switching valve may be composed of two valves, and the switching is not limited to manual operation.

[0023]

As described above, according to the brake display device for a working vehicle according to the present invention, when the main brake pressure is applied, whether or not the main brake indicator light is turned on according to the operating state of the parking brake device. Since it is controlled, even if the pressure acting on the main brake device is detected by the common pipeline of the work brake circuit and the main brake circuit, the main brake indicator light will be lit during work and the main brake pressure will be detected during running. The main brake indicator light does not light up even when there is a backlash, and the work brake state is displayed reliably.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a pressure circuit of a main brake device and a parking brake device to which a brake display device according to the present invention is applied.

FIG. 2 is a circuit diagram of a brake indicator lamp to which the device of the present invention is applied.

FIG. 3 is a schematic diagram of a pressure circuit of a second embodiment corresponding to FIG.

FIG. 4 is a circuit diagram of a second embodiment corresponding to FIG.

5 is a conventional pressure circuit diagram corresponding to FIG.

FIG. 6 is a side view of a conventional brake switching valve 3.

FIG. 7 is a circuit diagram of a conventional brake display lamp.

[Explanation of symbols]

 21: Pressure source 23: Brake valve for traveling 24: Brake switching valve 25: Parking brake device 26: Main brake device 32: Main brake pressure switch 3,39: Parking brake pressure switch 35: Relay 35a: Relay coil 35b: Normally closed Contact 36: Main brake indicator lamp 37: Parking brake indicator lamp

Claims (1)

[Scope of utility model registration request] 1. A brake switching valve provided between the pressure source and the main braking device and between the pressure source and the parking braking device is operated to switch the brake devices when traveling and to activate the parking braking device when parking. In a brake display device of a work vehicle that forms a brake circuit that operates both brake devices during work, the main brake display is displayed when the operating state of the main brake device is detected and the operating state of the parking brake device is detected. A brake display device for a work vehicle, wherein a light is turned on and a main brake indicator light is turned off when an operating state of the parking brake device is not detected even if a pressure state of the main brake device is detected.