JPH0245099Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a parking brake device comprising a center brake installed on a propeller shaft.

By equipping an automobile with a compressor and an air tank, various operations can be performed by operating various air cylinders using compressed air as a working medium. In a vehicle equipped with such an air tank, if the internal pressure of the air tank drops below a predetermined pressure for some reason, there is a possibility that the various operations described above will not be performed. Therefore, in vehicles equipped with air brakes, a spring brake cylinder is incorporated into the air brake, and when the air pressure inside the air tank drops below a predetermined value, the air brake is activated by this brake cylinder. , making it impossible for the vehicle to run.

That is, by incorporating a spring brake cylinder into the air brake, the air brake is operated as an emergency brake. However, in vehicles equipped with air-over type brakes or air servo type brakes, the brakes are ultimately operated by hydraulic pressure, so it is not possible to combine such brakes with a spring brake cylinder. Therefore, this brake cannot be used as an emergency brake.

The present invention was developed in view of these problems, and is applicable to vehicles equipped with brakes in which the service brake cannot be used in combination with a spring brake cylinder, such as an air over brake or an air servo brake. Another object of the present invention is to provide a parking brake device in which the parking brake functions as an emergency brake when the pressure of an air tank decreases.

The present invention will be explained below with reference to an illustrated embodiment.
The parking brake 1 shown in FIG. 1 consists of a center brake that is a separate brake from the service brake attached to the propeller shaft, and includes a drum 2 and a pair of brake shoes 3 disposed within the drum 2. and an S-type cam 4. The S-shaped cam 4 is fixed to an operating shaft 5, and a brake lever 6 is fixed to the operating shaft 5. The lever 6 is connected to an intermediate lever 8 by a wire cable 7. The intermediate lever 8 is rotatably supported by a bracket 9 and a pin 10, and its tip is connected to an operating lever 12 via a wire cable 11. The operating lever 12 is provided in the driver's seat as a means for manually operating the parking brake 1 (center brake), and by operating the operating lever 12, the driver can manually operate the parking brake 1. It's getting old.

Furthermore, the wire cable 1 is connected to the intermediate lever 8.
A spring brake cylinder 14 is connected via 3. Spring brake cylinder 14
As shown in FIG. 2, there is a piston 15 inside it.
This piston 15 is equipped with a spring 1.
Pressed by 6. In order to overcome the force of this spring 16, compressed air pressure is applied through a port 17 provided on the rear side of the cylinder 14. Also cylinder 1
An adjusting sleeve 19 for adjusting the stroke of the piston rod 18 is attached to the piston rod 18 of No. 4, and a clevis joint 20 is attached via this sleeve 19. The wire cable 13 is connected to this joint 20.

Next, the air circuit for supplying air pressure to the spring brake cylinder 14 will be explained with reference to FIG.
2 to a release tank 23. A release tank 23 is connected to an air tank 25 via a check valve 24. The air pressure in the air tank 25 is transferred to the cab control valve 27 via the release valve 26.
It is now being added to The cab control valve 27 is connected to a pressure control valve 28, and the pressure control valve 28 is connected to the spring brake cylinder 14. Note that the release valve 26 has a release port connected to the release tank 23. The compressed air in the air tank 25 is supplied as a working medium to various air cylinders (not shown) mounted on the vehicle.

In the above configuration, when the air pressure in the air tank 25 is maintained at a normal pressure, this pressure is applied to the spring via the release valve 26, cab control valve 27, and pressure control valve 28. It is applied to the brake cylinder 14, and the piston 15 of this cylinder 14 is in a state where it has moved forward to the left in FIG. 2 against the force of the spring 16. In this case, therefore, the spring brake cylinder 14 does not pull the intermediate lever 8, and the intermediate lever 8 is in a free state.

Therefore, in this case, the operating lever 12 provided on the driver's seat is rotated as a manual operating means,
The intermediate lever 8 is rotated by the wire cable 11, and the rotation of the lever 8 is transmitted to the S-shaped cam 4 via the wire cable 7 and the brake lever 6.
By transmitting this signal, it becomes possible to press the brake lining attached to the surface of the brake shoe 3 onto the drum 2 and operate the parking brake. That is, when the pressure in the air tank 25 is normal, the parking brake 1 exerts a braking force only when the operating lever 12 is operated. Note that when the operating lever 12 is rotated, the intermediate lever 8 is rotated counterclockwise in FIG. Since it is absorbed, no force is exerted on the spring brake cylinder 14.

Next, if the pressure inside the air tank 25 becomes lower than a predetermined pressure for some reason, this pressure is transmitted to the cab control valve 27 via the release valve 25. Then, the piston provided inside the cab control valve 27 moves, cutting off the supply of compressed air from the air tank 25 to the pressure control valve 28, and opening the exhaust port.
The air after this cab control valve 27 is exhausted. Therefore, spring brake cylinder 1
Since the force pushing the piston 15 of No. 4 is removed, the piston 15 is pushed to the right in FIG. 2 by the spring 16.

Therefore, as the piston 15 moves, the intermediate lever 8 is pulled via the rod 18, clevis joint 20 and wire cable 13. Therefore, the intermediate lever 8 rotates, and this rotational movement of the lever 8 causes the S
The mold cam 4 will be rotated. Therefore, in this case as well, the brake shoe 3 is pressed against the drum 2 and a braking action is performed.

That is, according to the parking brake device of this embodiment, if the pressure in the air tank 25 drops below a predetermined pressure for some reason, the cab control valve 27 acts to release the air to the spring brake cylinder 14. The supply of air pressure is cut off, and the parking brake 1 is activated, causing the parking brake to function as an emergency brake.
In this case, the intermediate lever 8 is rotated by the brake cylinder 14, but since the rotational movement of the lever 8 at this time is absorbed by the wire cable 11, no force is applied to the operating lever 12. do not have.

Next, brake 1 due to the decrease in air pressure mentioned above.
When releasing the brake, first release the air tank 25.
The cause of the drop in air pressure inside the air tank 25 will be investigated and repairs will be made to bring the pressure inside the air tank 25 above a predetermined pressure. When the knob of the release valve 26 is pushed in, compressed air is supplied from the release tank 23 to the cab control valve 27. Therefore, when the knob of the cab control valve 27 is pulled, this pressure is applied to the pressure control valve 2.
8 to the spring brake cylinder 14, for which this cylinder 1
The piston 15 of No. 4 is moved forward, and the braking of the brake 1 is accordingly released.

Next, a modification of the above embodiment will be explained with reference to FIG. In the above embodiment, the brake cylinder 1
The piston rod 18 of No. 4 and the intermediate lever 8 were connected by the wire cable 13, but in this modification, the rod 18 is connected to the connecting rod No. 3.
1 and the clevis joint 32 are connected to the intermediate lever 8. The stroke of the connecting rod 31 can be adjusted by screws formed at both ends thereof. Further, the clevis joint 32 is elongated and is provided with a long hole 33. This long hole 33 is the middle lever 8
It is adapted to be engaged with a pin 34 provided at the lower end of. Therefore, when the parking brake is normally operated, the pin 34 moves within the elongated hole 33 as the intermediate lever 8 rotates, thereby absorbing the rotation of the lever 8.

Next, another modification of the above embodiment will be explained with reference to FIG. In this modification, the air circuit that applies air pressure to the spring brake cylinder 14 is simplified. i.e. release valve 2
6, the control valve 28 and the release tank 23 are omitted. Even with such a configuration, the cab control valve 27
The parking brake 1 is used as an emergency brake in order to discharge the air in the brake cylinder 14 by moving the piston to open the exhaust port when the pressure in the air tank 25 falls below a predetermined value. It will not prevent you from doing so.

Note that in this modification, since the pressure control valve 28 is omitted, the pressure inside the brake cylinder 14 changes according to the change in the pressure of the air tank 25, and therefore the spring brake cylinder 14 Fluctuations in the internal pressure may occur. Therefore, the spring 16 and the control valve 2 are arranged so that even if the pressure decreases to a level close to the operating pressure of the cab control valve 27, air pressure is applied to the piston 15 to overcome the force of the spring 16.
It is necessary to adjust the working pressure of 7.

Also, in this modification, the release valve 26
Because parking brake 1 is omitted,
When the emergency brake is activated, the knob of the cab control valve 27 can be pulled to release the emergency brake. However, if the pressure in the air tank 25 is below a predetermined pressure, the knob will return to normal even if the knob is pulled, so this release operation must be performed after the pressure in the air tank 25 is increased to a predetermined value or higher. Furthermore, according to this modification, the connection between the spring brake cylinder 14 and the air tank 25 is cut off by operating the knob of the cab control valve 27, so that the cab control valve 27 is not connected to the operating lever of the parking brake 1. This control valve 27 functions as a manual operation means instead of 12.
It also becomes possible to operate and release the parking brake 1.

As described above, the present invention relates to a parking brake device in which a spring brake cylinder is connected to a center brake. When the pressure drops below , it becomes possible to switch the parking brake to a braking state, and as a result, the parking brake also operates as an emergency brake. Therefore, it becomes possible to provide a highly safe parking brake device.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a parking brake device according to an embodiment of the present invention, Fig. 2 is a sectional view of a spring brake cylinder used in this parking brake device, and Fig. 3 is an intermediate view of a modification of the above embodiment. FIG. 4 is an enlarged front view of main parts showing a coupling mechanism between a lever and a brake cylinder, and FIG. 4 is a block diagram of a parking brake device according to a modification. In addition, in the symbols used in the drawings, 1... Parking brake, 2... Drum, 3... Brake shoe, 4... S-type cam, 8... Intermediate lever, 14
... spring brake cylinder, 16 ... spring, 18 ... piston rod, 25 ... air tank, 27 ... cab control valve.

Claims (1)

[Scope of utility model registration request] While the parking brake is composed of a center brake that is a separate brake from the service brake attached to the propeller shaft, in vehicles equipped with an air tank that stores compressed air to be supplied to the on-board air cylinder, the center brake is manually operated. and a spring brake cylinder that operates the center brake when the pressure of compressed air stored in the air tank drops below a predetermined value.