JPH0242926Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention is a viscous fluid restrictor for a hydraulic control device that has a land portion in contact with fluid and a member that cooperates with the land portion to determine the opening degree of the restriction. Regarding the mechanism.

[Conventional technology]

Conventionally, as a device using this type of viscous fluid throttling mechanism, there is a compensator throttling mechanism of a pressure compensation type flow rate regulating valve as shown in Fig. 5, as described in, for example, Japanese Utility Model Publication No. 55-39444. .

To explain this simply, fluid flows into the center of the flow path immediately downstream of the throttle opening a formed by the gap between the land portion 1a and the piston 2 on the inner wall surface of the cylinder 1 and the outer wall surface of the piston 2. A sloped surface 1b and a concave surface 2a are provided to form a part that is actively separated from the flow, and a relatively long and thin passage substantially parallel to the central axis of the piston 2 is provided following the flow path formed by both of them. A straight channel 3 is formed.

As a result, the fluid that has passed through the throttle opening a between the cylinder 1 and the piston 2 does not diffuse rapidly, and the effective flow area changes extremely smoothly, thereby preventing the generation of noise and vibration. .

[Problem that the invention attempts to solve]

However, in such a conventional viscous fluid throttling mechanism, when the control pressure of the pressure compensation type flow regulating valve is changed, the noise value changes to the curve shown by line a when the flow rate is large as shown in Fig. 6. However, when the flow rate is low, as shown by line b, a convex part with a high noise level occurs in a specific range of the low pressure region, and when the operating noise of the mechanical equipment itself is low in the low pressure region, this becomes even more pronounced. There was a problem with it being audible.

Therefore, considering that the flow condition after the fluid passes through the throttle opening is inappropriate in the low pressure region, an attempt was made to improve it by rounding the ridgeline 2b of the piston (see Figure 5). However, simply moving the location (pressure) where the noise level is high in the area will not make it go away, and the problem has not been fundamentally solved.

The purpose of this invention is to provide a viscous fluid restricting mechanism that can solve these problems.

[Means for solving problems]

Therefore, the viscous fluid restriction mechanism according to this invention is a restriction mechanism for a hydraulic control device that has a land portion in contact with the fluid and a member that cooperates with the land portion to determine the opening degree of the restriction. The inner wall surface of the land portion has a substantially linear cross-sectional shape including the central axis, and is an inclined surface inclined in the direction of enlarging the flow path, and the wall surface on the side of the member that determines the aperture opening, which is opposite to the inclined surface, is centered on the inner wall surface of the land portion. The shape of the cross section including the axis is a concave surface having a tapered surface on the upstream side that defines the aperture opening and a corner on the downstream side thereof, and the slope of the land portion and the corner of the concave surface of the member that determines the aperture opening. Therefore, a second throttle is formed to provide back pressure, and a plurality of notches extending in the axial direction from the vicinity of the ridge line of the tapered surface of the member to the downstream portion are provided at intervals in the circumferential direction.

[Effect]

According to the viscous fluid throttling mechanism configured in this way, the flow passing through the valve is the sum of the flow from the ridgeline portion and the flow from the plurality of notches, and the flow condition that causes the noise level is eliminated.

In addition, the fluid flowing out downstream from the multiple notches provided from the vicinity of the ridgeline of the member that determines the throttle opening to the downstream part flows to the slope of the land portion and the corner of the concave surface of the member that determines the throttle opening. Since the air flows out into the recessed portion which is provided with back pressure by the second restrictor thus formed, the pressure drop is also small, making it possible to prevent the occurrence of cavitation, thereby making it possible to prevent noise.

〔Example〕

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

Fig. 1 is an enlarged cross-sectional view showing only the pressure compensator section of a pressure-compensated flow regulating valve to which this invention is applied, Fig. 2 is a sectional view showing the entire pressure-compensated flow regulating valve, and Fig. 3 is the same. It is a perspective view showing only the piston, and parts corresponding to those in FIG. 5 are given the same reference numerals.

First, to explain its configuration, as shown in FIG. 2, a land portion 1a in contact with fluid is provided inside a valve body 1 that also serves as a cylinder.
A piston 12, which is a member that determines the aperture opening in cooperation with the piston 12, is provided to be slidable in the direction of arrow A, and the aperture aperture a is adjusted by the land portion 1a and the piston 12, as shown in FIG. A first aperture 10 is formed.

Immediately downstream of the aperture a (to the left in Figure 1),
The inner wall surface of the land portion 1a is an inclined surface 1b whose cross-sectional shape including the center line is substantially straight and inclined in the direction of enlarging the flow path, and the wall surface on the side of the piston 12 facing the inclined surface 1b includes the center axis. A concave portion 16 is formed as a concave surface 12a having a tapered surface 12b on the upstream side (right side in the figure) whose cross-sectional shape defines the aperture aperture a and a corner portion 12c on the downstream side, and the sloped surface 1b of the land portion 1a. A second restriction 14 is formed by the corner portion 12c of the piston 12, and a back pressure is applied to the recessed portion 16.

Further, from the vicinity of the ridge line l to the downstream portion of the tapered surface 12b of the piston 12, as best shown in FIG. 3, a plurality of notches 15 facing in the axial direction are provided at intervals in the circumferential direction. (Four pieces in the illustrated example).

As shown in FIG. 2, the piston 12 has a through hole 1 extending radially through the center in the longitudinal direction.
2d, and a center hole 12e that communicates the through hole 12d with a chamber B provided at one end of the piston 12.

This piston 12 is connected to a spring 17 provided in a spring chamber C formed in the valve body 1.
is always biased to the left in FIG.

Further, the valve body 1 includes a flow passage 13 extending downstream of the second throttle 14, an outflow passage 19 that communicates the flow passage 13 with the tank 18, an inflow passage 21 that communicates with the hydraulic pump 20, and an inflow passage 19 that communicates with the tank 18. 21 and an output flow path 22 connected to an external load such as an actuator, etc.
A flow rate adjusting throttle valve 23 and a pilot flow path 24 having a narrow diameter that communicate the output flow path 22 and the spring chamber C are provided in the middle thereof.

A pilot relief valve 25 is provided between the hydraulic pump 20 and the inflow passage 21 to prevent the inflow pressure from rising above a set value.

Next, the operation of this embodiment configured as described above will be explained.

In this pressure compensated flow rate regulating valve, the hydraulic pump 2
The pressure P ₁ on the primary side applied to the inflow path 21 from 0 is applied to the chamber B through the through hole 12d and the center hole 12e of the piston 12, and acts to push the piston 12 to the right in FIG.

On the other hand, the pressure P ₁ applied to the inflow path 21 is subjected to throttle resistance by the flow rate adjustment throttle valve 23, becomes pressure P ₂ on the secondary side, operates an actuator, etc. (not shown), and reduces the pilot flow. The spring 17 joins the spring chamber C through the channel 24.
The first throttle 1
A required diaphragm aperture a (see FIG. 1) is formed at 0.

That is, the pressure on the primary side P ₁ and the pressure on the secondary side P ₂
The difference is almost constant regardless of the load pressure on the actuator, etc.

Therefore, if the pressure _P2 is now lowered, the spring chamber C is
As the pressure applied to the piston 12 decreases, the piston 12 moves to the right in the figure, widening the aperture aperture a, moves to a position where the forces applied to both ends are balanced, and stops.
The primary side pressure _P1 also decreases.

At this time, the fluid flowing out into the flow path 13 expanding downstream through the throttle opening a also flows out from the plurality of notches 15 provided in the piston 12, resulting in the high pressure and flow rate of the noise level shown in FIG. Noise-generating flow situations are eliminated even in the combined state.

Further, the fluid that has passed through the aperture opening a is directed to a concave portion provided with back pressure by a second aperture 14 formed by the inclined surface 1b of the land portion 1a and the corner portion 12c of the piston 12, as shown in FIG. 16, and cavitation does not occur due to the influence of the back pressure. As shown in Figure 7, the noise level characteristics with respect to the control pressure are approximately linear, and the noise level suddenly increases in a specific range of the low pressure region. Things like that will no longer be the case.

Note that in the flow path 13 according to this embodiment shown in FIGS. 1 and 2, compared to the conventional straight flow path 3 shown in FIG. 5, the portion of the flow path substantially parallel to the central axis of the piston Although the noise level will be a little higher because there is no flow path, the length of the flow path can be shortened, making it possible to downsize the entire flow rate regulating valve.

Furthermore, it goes without saying that if the shape of the flow path is made similar to the linear flow path 3 of the conventional example, the effects of the conventional example can also be obtained.

FIG. 4 shows another embodiment in which this invention is applied to a relief valve, in which a seat 31 fixed to a valve body 30
A land portion 31a having an inclined surface 31b is provided. The piston 32 is formed with a concave surface 32a, a tapered surface 32b, a corner 32c, and a notch 35 similar to those in the above-described embodiment, and a second aperture 34
This allows back pressure to be applied to the recess 36.

In this embodiment as well, the fluid that has passed through the aperture a flows through the notch 35 into the recess 36 where back pressure is applied, so cavitation does not occur, so the same effect as in the previous embodiment can be obtained. can.

[Effect of idea]

As explained above, the viscous fluid throttling mechanism according to this invention allows the fluid to flow downstream from multiple notches provided from the vicinity of the ridgeline to the downstream portion of the member that determines the throttling opening, and the fluid flows to the land. Cavitation is prevented from occurring by causing the flow to flow into the concave part with back pressure due to the second constriction formed by the inclined surface of the part and the corner of the concave part of the member that determines the aperture opening. The noise level does not suddenly increase in a specific range in the low pressure region, and it is possible to reliably prevent the occurrence of harsh noise in the entire low pressure and high pressure ranges.

[Brief explanation of drawings]

Fig. 1 is an enlarged cross-sectional view showing only the pressure compensator section of a pressure-compensated flow regulating valve to which this invention is applied, Fig. 2 is a sectional view showing the entire pressure-compensated flow regulating valve, and Fig. 3 is the same. A perspective view showing only the piston, FIG. 4 is a sectional view of main parts showing another embodiment in which this invention is applied to a relief valve, and FIG. 5 is a sectional view showing an example of a conventional pressure-compensated flow rate regulating valve. 6 and 7 are diagrams showing the noise level characteristics with respect to the control pressure of the conventional pressure compensator and the pressure compensator to which this invention is applied, respectively. 1a, 31a...Land part, 1b, 31b...
... Inclined surface, 12, 32 ... Piston (member that determines the aperture opening), 12a, 32a ... Concave surface, 12b,
32b...Tapered surface, 12c, 32c...Corner part,
14, 34... second aperture, 15, 35... notch.

Claims (1)

[Scope of utility model registration request] In a throttle mechanism for a hydraulic control device having a land portion in contact with fluid and a member that cooperates with the land portion to determine the throttle opening, the inner wall surface of the land portion immediately downstream of the throttle opening includes a center axis. An inclined surface having a substantially straight cross-sectional shape and inclined in the direction of enlarging the flow path, and the shape of the cross section including the central axis of the wall surface on the side of the member that determines the aperture opening, which faces the inclined surface, defines the aperture opening. The concave surface has a tapered surface on the upstream side and a corner on the downstream side, and a second aperture is formed by the inclined surface of the land portion and the corner of the concave surface of the member that determines the aperture opening. A viscous fluid throttling mechanism, characterized in that a plurality of notches are provided at intervals in the circumferential direction from the vicinity of the ridge line of the tapered surface of the member to the downstream portion thereof to provide back pressure.