JPS6229683Y2 - - Google Patents

Description

[Detailed description of the invention] Hydraulic cylinders for cabin tilting of freight vehicles are delivered to automobile manufacturers by hydraulic cylinder manufacturers with oil held inside, and the automobile manufacturers operate the cylinders by removing the blind plug from the delivered hydraulic cylinders. Perform the work of assembling it into the system. The problem in this work is how to exhaust the air that enters when removing the blind plug and assembling the hydraulic cylinder to the operating system. In this specification, a method is generally adopted in which air is discharged by operating a pump (referred to simply as a pump) and removing one of the piping connections to release oil. The operation of discharging air in this manner (referred to as air bleeding in this specification) is not only troublesome, but also often forces the air into areas where it is difficult to discharge.

In this case, the piston is raised (cabin tilt) when both the upper working chamber and the lower working chamber are communicated with the discharge side of the pump, and the upper working chamber is connected to the discharge side of the pump. When the lower working chamber is communicated with the oil drain side, the piston is lowered (the cabin returns to the horizontal position), and a check valve is installed to prevent oil from being discharged from the lower working chamber. Regarding the type equipped with a hydraulically operated small piston that releases the check valve, we focused on the structure near the lower working chamber where the check valve and small piston are installed, and developed a simple structure. This allows air to be removed easily.

1 to 3 are explanatory diagrams of an air bleed device according to the present invention, and in the following, the above-mentioned type will be explained first, and then the parts provided according to the present invention will be explained.

In FIG. 1, 1 is a hydraulic cylinder for tilting the cabin, 2 is its piston, 3 is a pump, 4 is an oil tank, 5 is a flow path switching valve, 6 is a relief valve, and 7 is a hydraulic cylinder for tilting the cabin.
is a pressure oil flow path from the pump 3 to the flow path switching valve 5,
Reference numeral 8 denotes a drain oil flow path leading from the flow path switching valve 5 to the oil tank 4; 9 a flow path communicating with the working chamber 10 above the hydraulic cylinder 1 via a throttle (not shown); and 11 the flow path below the hydraulic cylinder 1. This is a flow path that communicates with the working chamber 12 via the throttle 13.

When the operating system is assembled into the hydraulic cylinder 1, the piston 2 of the hydraulic cylinder 1 is at the bottom dead center position (so that the hydraulic cylinder 1 does not lock the oil).
The upper surface 16 of the piston 2 is in a lowered position beyond the port 17).

18a, 18b, and 18c are check valves, and among these check valves, check valve 18 is
A functions to prevent oil from flowing out from the lower working chamber 12. Reference numeral 19 denotes a hydraulically operated small piston that releases the oil outflow prevention action, that is, the check action performed by the check valve 18a.

The elements listed above are well known for cabin tilt hydraulic cylinders of the type described above.

In the case according to the present invention, the lower working chamber 12
A bypass flow path 14 is provided which communicates a first flow path for supplying and discharging oil to the small piston 19 and a second flow path for supplying pressure oil to the small piston 19.
An on-off valve 15 is provided on this flow path. The point of communication between the first channel and the bypass channel 14 is indicated by the symbol f, and the point of communication between the second channel and the bypass channel is indicated by the symbol e.

When the hydraulic cylinder 1 is assembled into the operating system, the piston 2 is at the bottom dead center position, as pointed out earlier. To bleed air, open/close valve 1 in this state.
This is done by operating the pump 3 after opening the pump 5. (See Figure 3) In that case, the oil discharged from the pump 3 is a→b→c→d→bypass passage 14→
The air that flows under the path called oil tank 4 and enters as a replacement when the hydraulic cylinder is installed reaches the oil tank 4 using oil as a conveying medium. The air that has reached the oil tank 4 rises to the surface and is dissipated into the atmosphere.

The operating time of the pump 3 required for air removal is relatively short. When the air removal is completed, the on-off valve 15 is returned to the state shown in FIG. 2 in which the bypass passage 14 is closed.

The device according to the present invention described above allows air to be quickly and completely removed from the cabin tilt system of a truck without any troublesome operations, and its construction is extremely simple.

[Brief explanation of drawings]

FIG. 1 is a drawing showing the main parts of a hydraulic cylinder for cabin tilt of a freight vehicle equipped with a device according to the present invention;
FIGS. 2 and 3 are views showing the bypass passage shown in FIG. 1 in a different state. 1... Hydraulic cylinder, 2... Piston, 3...
Pump, 4...Oil tank, 5...Flow path switching valve, 6
... Relief valve, 7 ... Pressure oil flow path, 8 ... Drain oil flow path, 9 ... Upper working chamber side flow path, 10 ... Upper working chamber, 11 ... Lower working chamber side flow path , 12...
... lower working chamber, 13 ... throttle, 14 ... bypass passage, 15 ... on-off valve, 16 ... upper surface of piston, 17 ... port, 18a-18c ... check valve, 19 ... small piston.

Claims (1)

[Scope of utility model registration request] The piston rises (cabin tilt) when both the upper working chamber and the lower working chamber are communicated with the discharge side of the pump, and the upper working chamber communicates with the discharge side of the pump and the lower working chamber communicates with the discharge side of the pump. A check valve that prevents oil from being discharged from the lower working chamber by lowering the piston (returning the cabin to the horizontal position) when the chamber is communicated with the oil drain side, and a non-return action of this check valve. In a type in which a hydraulically actuated small piston for releasing the pressure is provided for the lower working chamber, there is a first flow path for supplying and discharging oil to the lower working chamber and a pressure oil supply passage for the small piston. An air bleed device for a hydraulic cylinder for cabin tilt of a freight vehicle, characterized in that a bypass flow path communicating with a second supply flow path is provided, and an on-off valve is provided on the bypass flow path.