JP3817155B2 - Spring brake device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a spring brake device.
[0002]
[Prior art]
Conventionally, some large vehicles such as trucks and buses have a spring brake device as a parking brake.
[0003]
FIG. 2 shows an example of a spring brake device. In FIG. 2, reference numeral 1 denotes a service brake tank. The service brake tank 1 is divided into a front chamber 2, a wet chamber 3 and a rear chamber 4 in its interior. The high-pressure working air introduced from the air compressor 5 through the air dryer 6 is introduced into the wet chamber 3, and the high-pressure working air is supplied from the wet chamber 3 to the spring brake tank 8 through the 4-way protection valve 7. It is like that.
[0004]
The operating air of the spring brake tank 8 is guided toward the spring brake main body 10 via the relay valve 9. In the example shown here, the air is operated to the spring chamber 11 of the spring brake main body 10. When the air is supplied, the push rod 12 is immersed in the spring chamber 11 against the resilience of the compression spring 13, whereby the spring brake body 10 is deactivated and the wheel 14 is unlocked. Thus, when the supply of operating air is shut off by the relay valve 9, the push rod 12 protrudes from the spring chamber 11 by the elastic force of the compression spring 13, and the wheel 14 is locked. ing.
[0005]
Here, the relay valve 9 is opened by a signal pressure introduced from the spring brake tank 8 via the spring brake operation valve 15, more specifically, the parking brake lever 16 is operated. When the spring brake operation valve 15 is opened, a signal pressure is sent to the relay valve 9 to open the relay valve 9 and the parking brake lever 16 is returned to its original position. The operation valve 15 is closed and the signal pressure is not sent to the relay valve 9, and the relay valve 9 is closed by the disappearance of the signal pressure.
[0006]
The high-pressure working air introduced into the wet chamber 3 of the service brake tank 1 is also supplied to the front chamber 2 and the rear chamber 4 via the 4-way protection valve 7. The working air introduced into the rear chamber 4 is sent to the front and rear brake boosters (not shown) via a brake valve 18 interlocked with the brake pedal 17 in the driver's seat. It is supposed to be.
[0007]
Here, the operating air sent out via the brake valve 18 linked to the brake pedal 17 in the driver's seat may be used as direct operating air for pushing the power piston of the brake booster (mainly in the case of a medium-sized vehicle). It may be used as a signal pressure for a relay valve for separately guiding direct working air that pushes the power piston of the brake booster (mainly for large vehicles).
[0008]
However, this explanation is based on the premise that the service brake is an air / oil combined brake (air over hydraulic brake). A full air brake that obtains braking force by directly using the pressure of the operating air is used. When employed as a service brake, the working air that has passed through the brake valve 18 linked to the brake pedal 17 in the driver's seat is sent as a signal pressure to a relay valve (not shown).
[0009]
[Problems to be solved by the invention]
However, in the conventional spring brake device used in combination with such a service brake, the operation air stored in the spring brake tank 8 can be operated regardless of the pressure state on the service brake tank 1 side. Even if the pressure in the service brake tank 1 drops due to heavy use of the brake, etc., it is possible to release the spring brake body 10 freely from the stopped state and to start running, and to start running in a safer state Improvements are beginning to be considered.
[0010]
The present invention has been made in view of the above circumstances, and an object thereof is to improve safety by disabling the release of the spring brake body until the pressure in the service brake tank is sufficiently recovered.
[0011]
[Means for Solving the Problems]
The present invention guides the operating air from the spring brake tank through the relay valve to appropriately hold the spring brake body in a non-operating state, and the relay valve by the signal pressure introduced from the spring brake tank through the spring brake operation valve. In the spring brake device configured to open the
A normally open cut valve is provided in the middle of the path for guiding the signal pressure from the spring brake tank to the spring brake operation valve. A check valve for preventing the backflow of the working air from the spring brake operation valve side to the cut valve side is provided in the middle of the path for guiding the signal pressure to the spring brake operation valve.
[0012]
Thus, in this way, when the service brake tank is stopped with the service brake tank being lowered to a predetermined pressure or less due to heavy use of the service brake, the signal pressure derived from the service brake tank becomes the predetermined pressure or less. Therefore, even if the parking brake lever is released and the spring brake operation valve is opened, the signal pressure from the spring brake tank is not sent to the relay valve, and the pressure in the service brake tank is fully recovered. As a result, the spring brake body is held in an operating state until the cut valve is opened.
[0013]
In the driving state where the parking brake lever is released, even if the service brake tank drops below a predetermined pressure due to heavy use of the service brake and the cut valve is closed, the check valve closes the check valve. Since the signal pressure up to the relay valve is maintained, the spring brake main body is maintained in an inoperative state.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
FIG. 1 shows an example of an embodiment for carrying out the present invention, and parts denoted by the same reference numerals as those in FIG. 2 represent the same items.
[0016]
With respect to the spring brake device configured substantially the same as that of FIG. 2 described above, in this embodiment, the spring brake device is guided from the service brake tank 1 in the middle of the path for guiding the signal pressure from the spring brake tank 8 to the spring brake operation valve 15. A normally open cut valve 19 is provided that closes only under a condition where the signal pressure is equal to or lower than a predetermined pressure.
[0017]
Here, the cut valve 19 is of a conventionally well-known mechanism in which a valve body is movably provided therein and the valve body is held at a position where the flow path is opened by an elastic body. Only when a signal pressure is applied, the valve body moves to a position where the flow path is closed against the elastic force of the elastic body.
[0018]
In the example shown here, the signal pressure is guided from the front chamber 2 of the service brake tank 1 to the cut valve 19, but the signal pressure may be guided from the rear chamber 4.
[0019]
In addition, a check valve 20 that prevents the backflow of working air from the spring brake operation valve 15 side to the cut valve 19 side is provided in the middle of the path for guiding the signal pressure from the cut valve 19 to the spring brake operation valve 15. Provided.
[0020]
However, the check valve 20 can also be configured integrally with the outlet of the cut valve 19 or the inlet of the spring brake operation valve 15.
[0021]
Thus, when the vehicle is stopped in a state where the inside of the front chamber 2 of the service brake tank 1 drops below a predetermined pressure due to heavy use of the service brake, the signal pressure derived from the service brake tank 1 is obtained. Since the cut valve 19 is closed when the pressure becomes lower than the predetermined pressure, the signal pressure from the spring brake tank 8 is not sent to the relay valve 9 even if the parking brake lever 16 is released and the spring brake operation valve 15 is opened. The spring brake body 10 is maintained in the operating state until the pressure in the service brake tank 1 is sufficiently recovered and the cut valve 19 is opened.
[0022]
In the traveling state in which the parking brake lever 16 is released, even if the service brake tank 1 falls below a predetermined pressure due to heavy use of the service brake and the cut valve 19 is closed, the check valve 20 Since the signal pressure from the check valve 20 to the relay valve 9 is held, the spring brake body 10 is held in the non-operating state.
[0023]
Therefore, according to the above-described embodiment, even if the spring brake main body 10 is released from the stop state where the pressure in the service brake tank 1 is not sufficiently recovered, the release of the spring brake main body 10 can be prevented. Therefore, the vehicle can be started only in a state where a reliable braking force by the service brake can be obtained, so that the safety can be greatly improved . On the other hand, the vehicle is brought into a traveling state in which the parking brake 16 is released. is there, even if the service brake tank 1 by intensive like the service brake drops below a predetermined pressure, Ru can be reliably held spring brake body 10 to inoperative state.
[0024]
The spring brake device of the present invention is not limited to the above-described embodiments, and it is needless to say that various modifications can be made without departing from the gist of the present invention.
[0025]
【The invention's effect】
According to the above-described spring brake device of the present invention, even if an attempt is made to release the spring brake body from a stopped state where the pressure in the service brake tank has not sufficiently recovered, the release of the spring brake body can be prevented. there so, as may starts running only when the reliable braking force by the service brake can be obtained can be achieved significant improvement in safety, on the other hand, the running state parking brake is released it Te is the service brake tank by intensive like the service brake even drops below a predetermined pressure, an excellent effect Ru can reliably hold the spring brake body inoperative.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an embodiment for carrying out the present invention.
FIG. 2 is a schematic view showing a conventional example.
[Explanation of symbols]
1 Service brake tank 8 Spring brake tank 9 Relay valve 10 Spring brake body 15 Spring brake operation valve 19 Cut valve 20 Check valve

Claims (1)

Operating air is guided from the spring brake tank through the relay valve to appropriately hold the spring brake body in an inoperative state, and the relay valve is opened by the signal pressure introduced from the spring brake tank through the spring brake operation valve. In the spring brake device configured as follows,
A normally open cut valve is provided in the middle of the path for guiding the signal pressure from the spring brake tank to the spring brake operation valve. A spring brake device comprising a check valve for preventing a backflow of operating air from the spring brake operation valve side to the cut valve side in the middle of a path for introducing a signal pressure to the spring brake operation valve.

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