JPH0542246Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a cushion device for a liquid chamber cylinder.

[Conventional technology]

As shown in FIG. 4, this type of cushioning device has a hydraulic fluid supply/discharge line 9 connected to an end 32 of a cylinder 31 selectively connected to a hydraulic pump and a tank via a directional control valve (not shown). A sliding hole 37 that forms a passage 33, and connects the working fluid supply/discharge passage 33 and the cylinder liquid chamber 34 into which a cushion ring 36 protruding from the piston 35 enters, and a check valve that only allows fluid flow to the liquid chamber 34. After the sliding hole 37 is closed with 38 and the cushion ring 36, the hydraulic fluid supply and discharge passage 33 is opened from the fluid chamber 34.
A cushion valve 39 is provided to limit the amount of hydraulic fluid that flows out. (For example, see JISB8354 Hydraulic Cylinder).

Now, when the piston returns due to switching of the directional control valve, when the piston ring 36 rushes into the sliding hole 37 due to the inertia force of the inertial body, the hydraulic fluid in the fluid chamber 34, which has been cut off from communication with the hydraulic fluid supply/discharge passage 33, is removed. The cushion valve 3 is pushed by the piston 35 through the through hole 40.
As a result, the inertial body is braked by a cushion valve 39 that limits the amount of hydraulic fluid flowing out.

[Problem that the invention attempts to solve]

By the way, when the inertial body moves, the kinetic energy possessed by the inertial body is converted into thermal energy by the cushion valve 39, and the discharged liquid whose temperature has increased thereby merges with the working fluid from the pump. Therefore, if the pipe line connecting the cylinder 31 and the directional control valve is long, the working fluid in the pipe will not be replaced, which will cause the cylinder and the pipe line to reach abnormally high temperatures, leading to deterioration of the working fluid and sealing material. It was hot.

The present invention has been made in view of the above points, and an object of the present invention is to provide a hydraulic cylinder in which the inertial body can be reciprocated at high frequency without abnormal temperature rise in the cylinder and the pipe line.

[Means for solving problems]

The configuration of the present invention to achieve the above object is described in a second manner.
This will be explained using figures.

The working fluid supply/discharge passage 10 of the cylinder end 8 and the cylinder fluid chamber 3 are connected to the cushion ring 1 of the piston 11.
The cylinder liquid chamber 3 is also connected to a sliding hole 13 into which the cylinder liquid chamber 2 enters, and a first check valve 14 that allows fluid flow only to the cylinder liquid chamber 3. 16 to connect to the link,
A second check valve 17 that only allows fluid to flow from the cylinder fluid chamber 3 to the tank is provided in this passage, and a cushion valve 22 is provided downstream of this second check valve. is connected to the hydraulic fluid supply/discharge passage 10.

[Effect]

When the piston 11 returns due to switching of the directional control valve, when the cushion ring 12 rushes into the sliding hole 13 due to the inertial force of the inertial body, the hydraulic fluid in the fluid chamber 3, which has been cut off from communication with the hydraulic fluid supply/discharge passage 10, is Pushed by the piston 11 to overcome the tank fluid pressure acting on the spring chamber 18 of the second check valve 17 and the spring 24, the second check valve 17 is opened, and the water is discharged from the second check valve 17 via the cushion valve 22 to the tank. 6. At this time, since the amount of hydraulic fluid discharged is throttled by the cushion valve 22, the inertial body is braked, and as a result, it stops at the end of the stroke with almost no return shock.
In the return stroke, the same pressure (pump hydraulic pressure) acts before and after the second check valve 17, so the second check valve 17 is closed by the spring 24. Therefore, the discharged liquid whose temperature has increased when passing through the cushion valve 22 does not flow back to the cylinder side even during the piston return stroke, so that the cylinder and the pipe line are not heated.

〔Example〕

Embodiments of the present invention will be described based on the drawings. 1st
In the figure, a hydraulic cylinder 2 to which an inertial body 1 is connected
The liquid chambers 3, 3' are selectively connected to a hydraulic pump 5 and a tank 6 by a directional control valve 4, and are also connected to the tank 6 via a cushion device 7, 7'.

In FIGS. 2 and 3, the hydraulic cylinder 2
A directional control valve 4 is connected to the cylinder end 8 by a conduit 9.
It forms a hydraulic fluid supply and discharge passage 10 connected to the
The hydraulic fluid supply/discharge passage 10 and the liquid chamber 3 are connected to a sliding hole 13 into which the cushion ring 12 protruding from the piston 11 is inserted, and fluid flow is only allowed from the hydraulic fluid supply/discharge passage 10 to the liquid chamber 3. The liquid chamber 3 and the tank 6 are communicated through a first check valve 14, and a passage 16 connects the liquid chamber 3 and the tank 6, and a cushion device 7 is provided in the passage 16.

The cushion device 7 includes a second check valve 17 connected to the liquid chamber 3 and a cushion valve downstream thereof, a throttle valve 22 in this embodiment.
The spring chamber 18 of No. 7 is connected to the hydraulic fluid supply/discharge passage 10 through a flow path 19 .

The other cylinder end 8' through which the piston rod 23 passes has the same structure as the cylinder end 8, except that a through hole of the piston rod 23 and a sealing structure for sealing the piston rod 23 are provided in the through hole. Further, the cushion device 7' has the same structure as the cushion device 7.

[Effect of idea]

As is clear from the above explanation, according to the present invention, a tank is connected downstream of the cushion valve that absorbs inertial shock (return shock), and a second check valve is connected upstream of the cushion valve to connect the spring chamber to the hydraulic fluid supply and discharge passage. This completely eliminates the backflow of the discharged liquid, whose temperature has increased when passing through the cushion valve, toward the working fluid supply and discharge passage, thereby preventing heating of the cylinder and pipe line. Therefore, frequent reciprocating operation of the inertial body is possible.

[Brief explanation of the drawing]

Fig. 1 is a hydraulic circuit diagram of a hydraulic cylinder drive device according to an embodiment of the present invention, Fig. 2 is a partially cutaway hydraulic circuit diagram of an embodiment of the present invention, and Fig. 3 is a cross section of a cushion device according to the present invention. 4 are partially cutaway sectional views of the conventional device. 3... Cylinder liquid chamber, 7... Cushion device,
8... Cylinder end, 10... Working fluid supply and discharge passage,
11...Piston, 12...Cushion ring,
13...Sliding hole, 14...First check valve, 1
6... passage, 17... second check valve, 18...
...Spring chamber, 22...Cushion valve.

Claims (1)

[Scope of utility model registration request] The cylinder liquid chamber and the hydraulic fluid supply/discharge passage at the end of the cylinder are communicated through a sliding hole into which the cushion ring of the piston enters and a first check valve that allows fluid flow only to the cylinder liquid chamber. , a second check valve that communicates with the tank through a passage separate from the working fluid supply/drain passage and allows only fluid to flow from the cylinder liquid chamber to the tank; and a cushion downstream of the second check valve. A valve is provided, and
A cushion device for a liquid chamber cylinder, characterized in that a spring chamber of a second check valve is connected to the hydraulic fluid supply/discharge passage.