JPH052974Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The invention has a poppet valve connected to the main spool interposed between the cylinder port and the drain port, which are communicated with the hydraulic cylinder for driving the lift arm. Regarding position control valves for agricultural tractors.

[Conventional technology]

As shown in Japanese Utility Model Application Publication No. 57-100605, position control valves for agricultural tractors of this type can be used by screwing the valve seat of the poppet valve into the poppet hole in the direction of hole-closing operation. The most common structure is one that is tightened and fixed.

[Problem that the invention attempts to solve]

However, in the conventional structure, in order to arrange the poppet valve and the valve seat concentrically so that they can be brought into close contact, it is necessary to improve the alignment accuracy of the poppet hole and the screw hole for mounting the valve seat, which requires machining. It had become a difficult point.

In view of these circumstances, the present invention aims to solve the above-mentioned difficulties in machining by improving the means for fixing the valve seat to the control valve.

[Means for solving problems]

The characteristic structure of the present invention, which has been made to achieve the above object, is to make the drain port side of the poppet hole of the poppet valve smaller in diameter than the poppet hole,
The valve seat of the poppet valve is inserted from the direction of the valve closing operation and is fitted and held on the drain port side, and its functions and effects are as follows.

[Effect]

In other words, the valve seat of the poppet valve is inserted into the poppet hole from the direction in which the valve is closed, and is held in place by being brought into contact with the small diameter portion of the poppet hole on the drain port side.

[Effect of idea]

Therefore, according to the present invention, there is no need for screw machining, which is difficult to improve centering accuracy, and the machining effort is greatly reduced. In addition, it has become possible to assemble the valve seat with high precision and in a short time.

〔Example〕

Hereinafter, embodiments of the present invention will be described based on the drawings.

As shown in FIG. 4, a rotary tiller A is connected to the rear of an agricultural tractor T via a three-point linkage mechanism 2 that is raised and lowered by the operation of a lift arm 1.

As shown in FIG. 3, the support shaft 3 of the lift arm 1
A hydraulic arm 4 is fixed to and connected to a hydraulic rod 6 of a hydraulic cylinder 5, so that the lift arm 1 swings up and down in conjunction with the operation of the hydraulic cylinder 5.

Next, the control valve V for controlling the position of the hydraulic cylinder 5 will be explained using the structural diagram of FIG. 1 and the hydraulic circuit diagram of FIG. 2.

The control valve V is connected to the hydraulic cylinder 5
A poppet valve 11 connected to the main spool 7 via a spool operating lever 10 is interposed between a cylinder port 8 and a drain port 9, which are connected to the main spool 7.
and a check valve 13. and,
The positions of the hydraulic cylinder 5 and the lift arm 1 are maintained by sliding the main spool 7 and returning the oil pressure-fed from the gear pump port 14 to the transmission case M through the drain port 15 on the unload valve 12 side. Also, the oil is passed through the cylinder port 8 to the hydraulic cylinder 5.
Furthermore, the oil is sent to the poppet valve 1 so that the lift arm 1 is swung upward by sending the oil to the poppet valve 1.
At the same time, the oil in the hydraulic cylinder 5 sent from the cylinder port 8 is returned to the transmission case M through the drain port 9 on the poppet valve 11 side. 1 is adapted to be swung downward by the weight of the rotary tiller A.

The poppet valve 11 has a drain port 15 of a poppet hole 17 formed through the control valve V to have a smaller diameter than the poppet hole 17, and a cylindrical valve seat 18 is provided in the poppet hole 17 to close the valve 11. Insert the valve 11 from the direction of valve operation, contact the small diameter part, fit and hold it, and then insert the main body of the valve 11 into the poppet hole 17 of the bearing part 1.
While being positioned at 9, it is slidably fitted and held inside.

Note that although reference numerals are written in the claims section of the utility model registration for convenience of comparison with the drawings, the present invention is not limited to the structure of the attached drawings by such entry.

[Brief explanation of the drawing]

The drawings show an embodiment of the position control valve for an agricultural tractor according to the present invention, in which Fig. 1 is a sectional view, Fig. 2 is an overall hydraulic circuit diagram, Fig. 3 is a vertical side view of a hydraulic cylinder, and Fig. 4 is a cross-sectional view. The figure is a rear side view of the agricultural tractor. 5...Hydraulic cylinder, 7...Main spool, 8...
...Cylinder port, 9...Drain port, 11
...Poppet valve, 16...Drain port,
17...Poppet hole, 18...Valve seat.

Claims (1)

[Scope of utility model registration request] A position control valve for an agricultural tractor in which a poppet valve 11 connected to a main spool 7 is interposed between a cylinder port 8 communicating with a hydraulic cylinder 5 for driving a lift arm and a drain port 9, the poppet valve 11 being connected to a main spool 7. The drain port 9 side of the poppet hole 17 is made smaller in diameter than the poppet hole 17, and the valve seat 18 of the poppet valve 11 is inserted from the valve closing operation direction of the valve 11 and is fitted and held on the drain port 9 side. Tractor position control valve.