JPS6068410A - Reversible reducing valve - Google Patents

Abstract

PURPOSE:To obtain a miniature reversible valve by providing slidably a small spool to a pilot path so that an end of the spool is exposed to the pressure of the primary side and closing the pilot path by the land of the spool only when the pressure of the secondary side is higher than that of the primary side. CONSTITUTION:A miniature spool 6 is set slidably to a pilot path 8 which is led to an end face 5 of a main spool 4 from a secondary side B provided to a cover 3. The spool 6 is closed by plugs 20 and 22 and also pressed always toward the plug 22 by a spring 13. The pressure receiving surface 6' at an end of the spool 6 is exposed to the pilot pressure oil via the side B and the path 8. While the pressure receiving surface 6'' of the other end having almost the same area as the surface 6' is exposed to the pressure of a primary side B'. A sleeve part 6c which forms a land of the spool 6 cuts off a pilot oil path 8d only when the pressure P2 of the side B is higher than the pressure P1 of the side B'. Thus it is possible to obtain a miniature reversible reducing valve with which a reverse current is not limited by a decompressing action.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in fluid pressure reducing valves used in machine tools, industrial machinery, etc., and more particularly to improvements in space-saving cartridge-type reducing valves.

A reducing valve used in a fluid pressure device such as a hydraulic device is inserted into an oil path that is sent from a pump to a cylinder through a switching valve, etc. For example, in FIG. Secondary side 1 on the cylinder side with respect to pressure (B)
Reduce pressure. For this purpose, pilot pressure oil is usually passed from the secondary side to the end of the main spool through the pilot passage (
8).

(9) is a drain oil passage. When the cylinder is returned,
When no other valve is used, the pressure oil in the cylinder must flow back through the reducing pulp (In) and return to the tank, i.e. in the opposite direction from the downstream side (B) to the It needs to be returned to (B').

However, in this case, the pilot pressure oil led from the secondary side also pushes the end of the main spool, so if the inflow pressure to the secondary side is close to the set pressure (secondary 1 μm 1 pressure), the reduction will occur. It is known that the single valve operates to reduce pressure, and when the pressure exceeds the set pressure, the main spool blocks the passage inside the valve from the secondary side to the primary side, preventing backflow. A check pulp (7) is installed as a bypass as shown in the figure, and the backflow is returned to the tank as a free flow through this check valve (7).However, in this method, a check of a size corresponding to the backflow amount is required. Pulp must be used, which increases the size of the valve, making it difficult to make it compact and increasing costs.

Alternatively, as shown in Figure 2, it is known to connect a reducing valve directly to the pressure oil port (P) from the pump and guide the pilot pressure oil through the passage (B'B) to the cylinder. It is being However, although this approach makes the valve more compact, it does mean that from the secondary side 113) to the
When pressure oil flows backward into 3'l, the pressure on the secondary side and the pilot pressure oil increase due to pressure loss, and when this approaches the set pressure, the reducing valve (]0 operates to reduce the pressure and limit the flow rate of backflow. There are drawbacks to reducing it.

The present invention eliminates the drawbacks of such conventional products and provides a reducing valve capable of backflow, which does not use a check valve in parallel, is compact and inexpensive, and whose backflow is not restricted by pressure reduction operation. The purpose is to

Therefore, in the present invention, pilot pressure oil is guided from the secondary side to the end of the main spool via the pilot passage so as to reduce the pressure on the secondary side of the pressure oil flowing from the secondary side to the secondary side. In the reducing valve, a small spool is provided in the pilot passage, the pressure receiving surface of one end of which is exposed to the pilot pressure oil, and the pressure receiving surface of the other end of approximately the same area as that of the small spool exposed to the pressure on the primary side via the oil passage. is slidably inserted therein, and the small spool is a reversible reducing valve configured to close the pilot passage by the land of the small spool only when the outlet pressure is higher than the inlet pressure. It is. According to this configuration, when there is a backflow from the secondary side to the primary one law, the secondary 1111 pressure is always higher than the primary side pressure, so the land of the small spool closes the pilot passage and does not perform a pressure reduction operation, so the pressure decreases during the backflow. The secondary side pressure increased due to the influence of the loss, and the pressure of the pilot pressure oil approached the set pressure, allowing the pressure to be reduced and the flow rate to no longer be restricted. Furthermore, since there is no need to use check pulp in parallel and only a small piston is inserted into the pilot passage, it is compact and inexpensive.

Next, embodiments of the present invention will be described with reference to the drawings. 3 and 4 show cross-sectional structural views showing one embodiment, and FIG.
The figure shows the hydraulic J/S symbol. In Figure 3, the reversible reducing valve is of the balanced piston type, and the pilot part (2) connects the main spool (4) to the main spool (4).
At part (a), the land (6) of the pilot pressure oil guided from the secondary side by the pilot passage (8) flows from the primary side (B) to the secondary side ■] to the main spool (4). The end of (
5) K acts to reduce pressure. The configuration of such a balanced piston type reducing valve,
The principle of pressure reduction operation is well known and will not be described in detail.

In this embodiment, a slidable small spool (6) is installed in a pilot passage (8) that is guided from the secondary side (B) provided on the cover (3) to the end face (5) of the main spool (4). It has been inserted. The small spool (6) is closed by a plug (c) and is constantly pressed toward the platen 2 by a spring Q3. The small spool (6) is connected to the poppet part (6a) by the small diameter part (6a) as shown in FIG.
c) and a sleeve part (6) forming the land of the small spool (6), and the small diameter part (6a) is provided with a radial hole (6d), and the sleeve part (six central holes (8)
Together with this, a pilot passage (8d) is formed. A spring q4 is inserted into the poppet portion (6b).

The pressure receiving surface at one end of the poppet portion (6b) (6 is the pressure receiving surface on the secondary side (
B) and pilot passage (8b, 80.8a, (3d)
The pressure receiving surface (6") at the other end, which has approximately the same area as the pilot pressure oil, is exposed to the pressure of the primary side (B) via the oil passage (field).

When the main spool (4) is currently under no load, the main spool (4) is pressed by the main spring aη, and its end face (5) is pressed against the cover (3). When pressure oil flows from the negative side (B'') to the secondary side (B), the pressure (Pl) on the negative side (B) is higher than the pressure (P2) on the secondary side 1. , the small spool (6) is in the position shown.The spring a4 is very weak to ensure this state./''The lower end of the spool (6) is in contact with the plug device, Pilot passage (8b, 8G, 8 (1, 6d,
8) is open and the valve operates to reduce pressure. The pilot pressure oil acts on the end (5) of the main spool (4), then the land (6), then the secondary Since the pressure (B2) of 1ull (f3) is higher than the pressure (Pl) of - next side (B), the small spool (6) moves upward and the soto pressure oil acts on the end face (5) of the main spool (4). Therefore, the valve does not operate to reduce pressure, and the land (6) of the main spool (4)
is fully opened at part (a), and the flow from the secondary trunk to the primary side (B1) is a free flow and is not affected by the pressure increase on the secondary side due to pressure drop. Also, since there is no need to install a check valve in parallel, it is compact and inexpensive. Since the small piston (6) may be small, the increase in space is extremely small.

[Brief explanation of drawings]

Figures 1 and 2 show a conventional reducing valve, Figure 3 is a cross-sectional structural diagram of a reducing valve that allows backflow, which is an embodiment of the present invention, and Figure 4 is a diagram of the reducing valve shown in Figure 3. The partially enlarged view, FIG. 4, shows the hydraulic JIS symbols in FIG. 3. 4...Main spool 5...End 6...Small spool 6+, 6"...Pressure receiving surface 6G...Small spool land 6eL, 8.8b, 8C, 8d...Pilot passage 1
2...Main spool land 13...Spring 19...Oil road agent Patent attorney Jun Kawachi Second procedure Amendment Written on October 31, 1981 Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent Application No. 174190 2, name of the invention Reducing valve capable of backflow 3, relationship with the case of the person making the amendment Patent applicant name (519) Fuji Koshi Co., Ltd. 4, agent residence Shiba Koen, Minato-ku, Tokyo 2-4-1 Hidekazu Shiba Park Building, 3rd floor, Part 6, Detailed description of the invention in the specification subject to amendment, Drawing 7, Contents of amendment 7.1 Page 6 of the specification, line 3 “Poppet portion (Correct bcJ to ``Poppet part (6b) J.'' 7.2 Correct figure 3 of the drawing as shown in the attached sheet.)

Claims (1)

[Claims] In a reducing valve in which pilot pressure oil is guided from the secondary ml to the end of the main spool via a pilot passage so as to reduce the pressure of the secondary I11 of pressure oil flowing from the primary side to the secondary side, A small spool having a pressure receiving surface at one end exposed to the pilot pressure oil and a pressure receiving surface at the other end having approximately the same area as the pilot pressure oil is slidably inserted into the pilot passage. has been
The small spool is configured to close the pilot passage by the land of the small spool only when the pressure on the secondary side is higher than the pressure on the primary side.