JPH0245584Y2 - - Google Patents

Description

[Detailed explanation of the invention] (a) Industrial application field This invention is a slow return system that is provided to make the speed of the contraction or extension operation slower than the speed of the extension or contraction operation of the hydraulic cylinder. This relates to check valves.

(B) Prior Art It has been known to provide a slow return check valve when extending or contracting a hydraulic cylinder to prevent damage or shock from occurring due to sudden expansion or contraction. The slow return check valve is a combination of a throttle valve and a check valve. Conventionally, as shown in FIG. 11, a slow return check valve B' with a throttle hole 20a' formed at the tip of the check valve 20b' was mounted in a valve case. Insert it into 4,
It has a structure in which a spring 20c with a low biasing force is brought into contact with the seat surface of the valve case 4, and when pressure oil is applied from the switching valve 7, the check valve 20b' is pressed against the spring 20c.
The check valve 20b' opens against the pressure, and the entire amount of pressure oil is sent toward the hydraulic cylinder 17. Conversely, the return oil from the hydraulic cylinder 17 is sent from the oil passage on the side of the check valve 20b' through the throttle hole 20a' without opening the check valve 20b'. The water was flowing in the direction of the drain.

(c) Problems that the invention aims to solve When the throttle valve of a slow return check valve is machined into a check valve, the throttle hole, once drilled, will not become smaller unless the check valve itself is reworked. This meant that I was unable to adjust the aperture.

(d) Means for solving the problem In view of the above points, the present invention is constructed as follows.

In a hydraulic system in which pressure oil from a hydraulic pump A is controlled by a switching valve 7 and supplied to and discharged from a hydraulic cylinder 17 via a slow return check valve B, a steel ball 22 is attached to a valve sleeve 20 of the slow return check valve B. Vertical hole 21a for installation
A valve seat 21b is formed at the tip of the steel ball 2.
A horizontal hole 21c is bored in the direction crossing the vertical hole 21a with an interval for accommodating the pins 21a and 21a, and the pin 23 is supported in the horizontal hole 21c.
A constricted portion is formed to communicate with c.

(e) Embodiment The purpose of the present invention is as described above, and the structure of the present invention will be explained based on the structure of the embodiment shown in the attached drawings.

FIG. 1 is a front view of the entire hydraulic system of the present invention. Figure 2 is also a partial plan view. Figure 3 is also a side view. FIG. 4 is a sectional view taken along line XX in FIG. 2. Fifth
The figure is also a YY sectional view in FIG. 4. Figure 6 is a side sectional view of the valve case. FIG. 7 is a hydraulic circuit diagram of the hydraulic system of the present invention. Figure 8 is a front sectional view of the slow return check valve. 9 and 10 are perspective views of the pin. FIG. 11 shows a conventional structure.

As shown in FIGS. 1 to 6, a case 3 and a valve case 4 are fixedly installed on both sides of a hydraulic oil tank 1, and a drive shaft 2 passes through the lower part of the hydraulic oil tank 1. 10 is an input pulley to which power from the engine is transmitted via a V-belt. At the upper end of the hydraulic oil tank 1 is a lubrication plug 1 with a breather mechanism.
1 and a cantilevered filter 12 at the bottom.
is disposed and communicates with the suction port 4a of the valve case 4.

A gear 5 is fixed on an extension shaft 9 disposed on an extension of the drive shaft 2 inside the valve case 4.
A hydraulic pump A is constructed by meshing with a gear 6 disposed at the inner rear. A relief valve 13 is disposed above it, and a switching valve 7 is disposed above it.
is installed. The switching valve 7 is of a rotary type, and a switching arm 14 is fixed to the end of the switching shaft 7a outside the case 19, and a pin 15 fixed to the switching arm 14 is connected to the float of the rice transplanter via a wire. The switching valve 7 is switched by the vertical movement of the float. Further, a pin 16 protruding from the lower end of the switching arm 14 is connected to a manual lever via a wire, allowing the operator to switch.

A cylinder port is provided at the upper end of the valve case 4, and joints 20 and 21 for connecting to a hydraulic cylinder 17 for raising and lowering the aircraft body are provided in the cylinder port. The joint 20
A slow return check valve B is installed inside, and a roll pin 23 shown in FIG. 9 as an embodiment of the present invention is fitted into a hole 21 penetrating the lower part of the joint 20 as shown in FIG. The roll pin 23 serves to prevent the steel ball 22 constituting the check valve from coming off, and its cross section is formed in a C shape, and the gap and hollow part are used as the throttle hole 2.
It is used as 0a, and roll pin 2
The aperture can be adjusted by changing the wall thickness of 3 or by changing the gap.

That is, as shown in FIG. 8, a steel ball 2 is attached to the valve sleeve 20 of the slow return check valve B.
A vertical hole 21a for assembling the valve seat 2 is provided at the tip.
1b, a horizontal hole 21c is bored in the direction crossing the vertical hole 21a at intervals to accommodate the steel balls 22, a pin 23 is supported in the horizontal hole 21c, and the pin 23 is
A constricted portion that communicates the vertical hole 21a and the horizontal hole 21c is formed in the hole. Further, as shown in FIG. 10, instead of the roll pin 23, a notch 25a may be provided at the engagement portion of the pin 25 with the hole 21 to communicate the inside and outside of the joint 20, and a pipe-shaped pin can be used. It is also possible to make an aperture hole in the center of the diaphragm.

(F) Function of the invention In this configuration, the function will be explained based on the hydraulic circuit shown in Fig. 7.

When the pulley 10 is rotated and the drive shaft 2 is rotated, the hydraulic pump A is activated, and hydraulic oil is sucked in from the filter 12 in the hydraulic oil tank 2, and into the hydraulic pump A from the suction port 4a of the valve case 4. It is converted into pressurized oil. When the switching valve 7 is in the neutral position, the pressurized hydraulic oil returns to the hydraulic oil tank 1 via the drain oil passage 4b, and the oil passages 4c and 4d leading to the joints 20 and 21 are closed.

Also, when the switching arm 14 rotates as the aircraft rises, or when the switching valve 7 is switched by manually rotating the hydraulic cylinder 17 in the direction of extension, the hydraulic cylinder 17 is moved from the oil passage 4d to the head side 17a. Supply oil and lengthen. Then, the hydraulic oil on the rod side 17b is supplied to the steel ball 2 of the check valve 20b.
2 is pressed against the seat surface of the joint 20 by hydraulic pressure and closed, so that it flows out of the joint 20 through the gap on the side of the roll pin 23 and the throttle hole 20a in the hollow part, and the hydraulic cylinder slowly expands. The hydraulic oil returns to the hydraulic oil tank 1 from the drain oil passage 4b via the oil passage 4c.

Conversely, when the aircraft is lowered and the switching shaft 7a is rotated to switch the switching valve 7, the hydraulic oil flows into the oil path 4c.
The check valve 20b is opened to send oil through the joint 20 to the rod side 17b, the hydraulic cylinder 17 is contracted, and the hydraulic oil in the head side 17a returns to the hydraulic oil tank 1 from the drain oil path 4b via the oil path 4d. It is. When the check valve 20b opens and the steel ball 22 floats within the joint 20, it is regulated by the roll pin 23 as described above. Excess pressure when the hydraulic cylinder 17 is extended or contracted is returned to the hydraulic oil tank 1 through the relief valve 13.

(G) Effects of the invention Due to the above-described structure and operation, the present invention has the following effects.

First, since the throttle valve can be constructed simply by inserting a pin to prevent the check valve from coming off, it has become possible to construct a slow return check valve with a simple structure and at low cost.

Second, since it is an in-line type, it can be screwed directly into the cylinder port, making it easy to assemble into the valve case.

Thirdly, by changing the diameter of the oil passage formed within the pin, it became possible to easily obtain any desired throttling effect.

[Brief explanation of the drawing]

FIG. 1 is a front view of the entire hydraulic system of the present invention. Figure 2 is also a partial plan view. Figure 3 is also a side view. FIG. 4 is a sectional view taken along line XX in FIG. 2. Fifth
The figure is also a YY sectional view in FIG. 4. Figure 6 is a side sectional view of the valve case. FIG. 7 is a hydraulic circuit diagram of the hydraulic system of the present invention. Figure 8 is a front sectional view of the slow return check valve. 9 and 10 are perspective views of the pin. FIG. 11 is a diagram of a conventional structure. A... Hydraulic pump, B... Slow return check valve, 1... Hydraulic oil tank, 2... Drive shaft, 7... Switching valve, 13... Relief valve, 20a... Throttle hole, 20b... Check valve , 22... steel ball, 23... roll pin.

Claims (1)

[Scope of utility model registration request] In a hydraulic system in which pressure oil from a hydraulic pump A is controlled by a switching valve 7 and supplied to and discharged from a hydraulic cylinder 17 via a slow return check valve B, a steel ball 22 is attached to a valve sleeve 20 of the slow return check valve B. Vertical hole 21a for installation
A valve seat 21b is formed at the tip of the steel ball 2.
A horizontal hole 21c is bored in the direction crossing the vertical hole 21a with an interval for accommodating the pins 21a and 21a, and the pin 23 is supported in the horizontal hole 21c.
A hydraulic device characterized by forming a constriction portion that communicates with c.