JPH03249414A - Hydraulic pilot valve - Google Patents

Abstract

PURPOSE:To reduce a shock at the time of starting a device by providing a middle diameter part either on the side of a tank port or of an entrance port of a small diameter part that communicates and cuts off the entrance port and a tank port on a spool, and by reducing the gap between the middle diameter part and a spool inserting hole. CONSTITUTION:A middle diameter part 20 is formed on the side of a tank port 9 in a small diameter port 4a of a spool 4, in an integrated manner, and a gap S1 for regulating return flow is formed between a spool inserting hole 21 of a valve 1 and the middle diameter part 20. When the spool 4 is in a neutral position, an entrance port 2 and an oil route 8 are cut off with each other, and pressure oil flows out of the gap S1 to the tank port 9. When the spool 4 is pushed down, until it is in a pressure oil supply position, the pressure oil of the entrance port 2 flows out of a gap S2 to the oil route 8, and runs from the oil route 8 to an exit port 3. Since the pressure oil which is narrowed when it flows in the gap S1 runs slowly, a shock can be reduced thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic pilot valve used in construction machinery, industrial machinery, and the like.

[Conventional technology]

As shown in FIG. 5, the valve body 1 is provided with a spool 4 that communicates and blocks the inlet port 2 and the outlet port 3, and the spool 4 is held in the blocking position by a spring 5, and the piston is moved by the swinging of the lever 6. A hydraulic pilot valve of a pressure reducing valve type is known in which pressure oil in an inlet port 2 is outputted to an outlet port 3 by pushing down the spool 4 and sliding the spool 4 in the communication direction.

Such a hydraulic pilot valve is used to supply hydraulic pressure to a pressure receiving part of a pilot-operated operating valve that supplies pressure oil to an actuator to switch the operating valve and operate the actuator. It is necessary to improve the response of the operating valve to the operation of the hydraulic pilot valve so that the actuator operates without delay.

For this purpose, as shown in FIGS. 6(a) and 6(b), an oil passage 8 is formed that communicates the small diameter portion 4a of the spool 4 with the output port 3, and when the lever 6 is not operated, the spool 4 is moved to the sixth position.
Outlet port 3 with oil passage 8 as the neutral position shown in Figure (a).
is connected to the tank port 9, and when the lever 6 is operated, the spool 4 is moved downward as shown in FIG. 6(b) to communicate the oil passage 8 with the inlet port 2. Opening area of inlet port 2 and oil passage 8 (outlet port 3) and tank port 9 for the stroke of
The opening area of the oil passage 8 (outlet port 3) is increased as shown in FIG. 7 to improve the responsiveness of the operating valve, thereby improving the responsiveness when starting the actuator and when stopping the actuator.

[Problem to be solved by the invention]

With such a hydraulic pilot valve, the change in the opening area when the spool 4 is moved in the direction of the pressure oil is the same as the change in the opening area when the spool 4 is moved toward the neutral position.
It is possible to improve the responsiveness when starting and stopping the actuator, but depending on the actuator, it may be necessary to improve the responsiveness only when starting or stopping. It may make your sex worse.

To solve this problem, as shown in FIG. The pressure oil flows smoothly from the pressure receiving part C to the outlet port 3, but the pressure oil is throttled and flows slowly to improve the response at startup and reduce the shock at stop. However, in this case, a slow return valve B is required in addition to the hydraulic pilot valve A, which not only increases cost but also requires piping work and reduces reliability with respect to oil leakage.

Therefore, an object of the present invention is to provide a hydraulic pilot valve that can solve the above-mentioned problems.

[Means and effects for solving the problem] An intermediate diameter part is provided on the tank port side or the inlet port side of the small diameter part of the spool that communicates and blocks the inlet port and the tank port, and the intermediate diameter part and the spool insertion hole are connected. Reduce the gap and throttle the pressure oil at the outlet port when it flows to the tank port,
This allows the pressure oil in the inlet port to be throttled when flowing to the outlet port.

〔Example〕

As shown in FIGS. 1(a) and (b), an intermediate diameter portion 20 having a slightly smaller diameter than the spool 4 and a larger diameter than the small diameter portion 4a is integrally formed on the tank port 9 side of the small diameter portion 4a of the spool 4. , a gap S1 for regulating the return flow rate is formed between the spool insertion hole 21 of the valve body 1 and the intermediate diameter portion 20, and this gap S
1 is made smaller than the supply flow rate regulating gap S2 formed between the spool insertion hole 21 and the small diameter portion 4a.

When the spool 4 is placed in the neutral position as shown in FIG. 1(a), the artificial port 2 and the oil passage 8 are blocked, and the oil passage 8 flows from the gap S to the tank port 9.

When the spool 4 is pushed down to the pressure oil supply position as shown in FIG. Since the gap S2 is large, the relationship between the opening area of the inlet port 2 and the oil passage and the spool stroke is shown in Figure 2 (X).
Since it is the same as the conventional one, the activation response of the actuator can be improved.

Furthermore, when the spool 4 is moved from the neutral position shown in FIG. 1(b) to the neutral position shown in FIG.
2 (Y ), and the pressure oil in the outlet port 3 flows through the gap S between the spool insertion hole 21 and the intermediate diameter portion 20.
, because it is throttled and flows slowly when flowing through, the responsiveness of the operating valve is reduced and the shock when the actuator stops can be reduced.

In the above embodiment, the intermediate diameter part 21 was provided on the tank port 9 side of the small diameter part 4a of the spool 4, but as shown in FIG.
, as shown in (b), the intermediate diameter portion 21 is connected to the artificial port 2.
If it is installed on the side, the relationship between the opening area and the spool stroke will be as shown in Figure 4 (X) and (Y), and the pressure oil in the inlet port 2 will slowly flow to the outlet port 3, improving responsiveness when starting the actuator. As a result, the pressure oil in the outlet port 3 smoothly flows to the tank port 9, improving responsiveness when the actuator is stopped.

〔Effect of the invention〕

If the intermediate diameter portion 20 is provided on the tank port side, the gap S1 between the intermediate diameter portion 20 and the spool insertion hole 21 will be reduced, and the gap S will be reduced when pressure oil from the outlet port 3 flows to the tank port 9.
, the flow is slow, so the shock when the actuator stops can be reduced while improving the startup response of the actuator.

If the intermediate diameter portion 20 is provided on the inlet port 2 side, the pressure oil in the inlet port 2 will be throttled and flow slowly when it flows into the oil passage 8, as described above, and this will improve the responsiveness when the actuator is stopped, while also improving the actuator's performance. The shock at startup can be reduced.

Further, since the intermediate diameter portion 20 is only provided in the small diameter portion 4a of the spool 4, the cost does not increase and the piping does not become complicated.

[Brief explanation of drawings]

Figures 1 (a) and (b) are cross-sectional views of the spool portion showing an embodiment of the present invention, Figure 2 is a chart showing the relationship between the opening area and the spool stroke, and Figures 3 (a) and (b). 4 is a diagram showing the relationship between the opening area and the spool stroke, FIG. 5 is a vertical sectional view of the hydraulic pilot valve, and FIGS. ) is a sectional view of a conventional spool part, FIG. 7 is a front view showing the relationship between the opening area and the spool stroke, and FIG. 8 is a hydraulic circuit diagram with a slow return valve. 1 is a valve body, 2 is an inlet port, 3 is an outlet port, 4 is a spool, 4a is a small diameter portion, 8 is an oil passage, 9 is a tank port, 20 is an intermediate diameter portion, and 21 is a spool insertion hole.

Claims (1)

[Claims] The spool insertion hole 21 of the valve body 1 is provided with an inlet port 2, an outlet port 3, and a tank port 9. A spool 4 is fitted and inserted, and this spool 4 is moved by swinging a lever 6 to supply pressure oil from the inlet port 2 to the outlet port 3 or to flow the pressure oil from the outlet port 3 to the tank port 9. In the hydraulic pilot valve, the spool 4 is provided with a small diameter portion 4a that communicates with and blocks off the inlet port 2 and the tank 9, and an oil passage 8 that communicates the small diameter portion 4a with the outlet port 3. A hydraulic pilot valve characterized in that an intermediate diameter portion 20 having a larger diameter than a small diameter portion 4a is provided on the tank port 9 side or the inlet port 2 side.