JPH04211769A - Spool valve - Google Patents

Abstract

PURPOSE:To reduce a fluid force generated in a spool valve and to maintain a sufficient strength even through a high pressure is applied to the spool. CONSTITUTION:A notch 2 is formed in an annular groove 1 formed on a spool (a), and an auxiliary notch 3 is formed in this notch 2. Further, the axis of the auxiliary notch 3 is laid substantially in parallel with a wall surface 2a of the notch 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a spool valve having a notch for reducing fluid force.

0002

[Prior Art] Fig. 5 shows a conventionally known Japanese Patent Application Publication No. 5
In the cross-sectional view of FIG. 4 shown in Publication No. 6-156563,
Notch 2 on side wall 1a side of annular groove 1 formed in spool a
is formed.

The notch 2 has a bottom surface 2a inclined so as to rise with respect to the axis, and a wall surface 2b on the depth side of the notch 2 is perpendicular to the bottom surface 2a, and is inclined with respect to the axis of the wall surface 2b. The inclination angle α is set to 90 degrees or more. Then, the generated fluid force F acting on the spool a can be determined by Equation 1 according to the law of momentum.

0004

[Equation 1] In Equation 1, ρ is the density of the fluid, Q is the flow rate, v is the flow velocity, and θ is the outflow angle.

As is clear from Equation 1, when the outflow angle θ becomes 90 degrees, cos θ becomes zero, so the fluid force generated in the axial direction of the spool a also becomes zero. and,
The conventional spool valve shown in FIG. 5 has a notch 2 as described above in order to increase the outflow angle θ. That is, when the notch 2 is formed, the fluids f1 and f2 flowing into the notch 2 hit the bottom surface 2a and the wall surface 2b of the notch 2, causing a flow f3 along the wall surface 2b.
However, as mentioned above, the inclination angle α of this wall surface 2b is 9
Since it is 0 degrees or more, the outflow angle θ of the flow f3 also becomes large. The deeper the cut depth of the notch 2 is, the more remarkable the effect of reducing the generated fluid force becomes.

In the conventional example shown in FIG. 5, an inching notch 2c is formed continuous with the notch 2, but this inching notch 2c is not for inching control. , it does not function in any way to reduce fluid force.

[0007]

[Problems to be Solved by the Invention] When attempting to increase the cutting depth of the notch 2 in the spool valve as described above, the effective cross-sectional area of the spool a at the deepest part of the notch 2 becomes smaller. When the effective cross-sectional area of spool a becomes smaller, when high pressure is applied to the spool valve, tensile stress increases in the portion where the effective cross-sectional area becomes smaller, and spool a may be torn off. For this reason, this conventional spool valve has a problem in that when it is used at high pressure, the cutting depth of the notch 2 cannot be made very deep, and the generated fluid force cannot be sufficiently reduced.

An object of the present invention is to provide a spool valve that maintains a sufficient notch depth and is not torn off even when high pressure is applied.

[0009]

[Means for Solving the Problems] This invention provides a spool a.
An annular groove 1 is formed in the annular groove 1, and a notch 2 is formed in the side wall 1a of the annular groove 1, and the notch 2 consists of a bottom surface 2a and a wall surface 2b, and the wall surface 2b is at an angle of 90 degrees with respect to the axis.
This is based on a spool valve that maintains an inclination angle α greater than 1°. Based on the above-mentioned spool valve, the present invention includes forming an auxiliary notch 3 consisting of a hole with one end opened in the bottom surface 2a, and making the axis of the auxiliary notch 3 substantially parallel to the wall surface 2b. Has characteristics.

0010

[Operation] The fluid that has flowed into the notch 2 is
and the auxiliary notch. The outflow angle of the fluid flowing out along this auxiliary notch becomes larger.

[0011]

[Embodiment] In the first embodiment shown in FIGS. 1 and 2, a notch 2 similar to the conventional one is formed on the spool a, and an auxiliary notch 3 consisting of a hole is formed along the wall surface 2b of this notch 2. This is what I did. The auxiliary notch 3 maintains an inclination angle α with respect to the axis, is parallel to the wall surface 2b, and has one end opening 3a open toward the bottom surface 2a. Moreover, this auxiliary notch 3 has the above-mentioned one end opening 3
a is located close to the annular groove 1, the other end bottom 3b is located far from the annular groove 1, and the bottom 3b is deeper than the bottom surface 2a of the notch 2. Therefore, in this first embodiment, the length of the wall surface 2b of the conventional notch 2 is extended.

Now, when fluid flows into the notch 2 from the annular groove 1, the fluid flows along the bottom surface 2a of the notch 2, as shown by the arrow 4 in FIG. After lowering, press the corresponding auxiliary notch 3.
and flows out along the wall surface 2a of the notch 2. As mentioned above, in this first embodiment, the fluid flowing into the notch 2 flows out while being guided not only to the wall surface 2b but also to the auxiliary notch 3, so it is similar to increasing the fluid guiding force of the wall surface 2b. Therefore, the outflow angle θ can be kept large accordingly.

In the second embodiment shown in FIGS. 3 and 4, an auxiliary notch 3 is formed within the notch 2, but this point is similar to the first embodiment. However, in this second embodiment, the phase of the auxiliary notch 3 is shifted in the direction away from the annular groove 1 along the axis. Since the phase of the auxiliary notch 3 is shifted in this way, the opening 3a of the auxiliary notch 3 opens slightly into the land portion 5 of the spool a, as shown in FIG.

Since the opening 3a of the auxiliary notch 3 is opened in the land portion 5, the degree of opening of the notch relative to the displacement of the spool becomes gentle. Therefore, the operability such as inching can be performed smoothly.

[0015]

[Effects of the Invention] As the fluid that has flowed into the auxiliary notch formed in the notch as described above flows out along this auxiliary notch, the outflow angle becomes very large and the generated fluid force can be suppressed to a small level. . Moreover, since the axis of this auxiliary notch is made almost parallel to the wall surface of the auxiliary notch, the effective cross-sectional area of the spool does not become small.
The desired strength can be maintained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of essential parts of a first embodiment.

FIG. 2 is a plan view of essential parts of the first embodiment.

FIG. 3 is a sectional view of essential parts of a second embodiment.

FIG. 4 is a plan view of main parts of the second embodiment.

FIG. 5 is a sectional view of a conventional main part.

[Explanation of symbols]

a Spool 1 Annular groove 1a Side wall 2 Notch 3 Auxiliary notch 3a Opening 3b Bottom

Claims (1)

[Claims] 1. An annular groove 1 is formed in a spool a, a notch 2 is formed in a side wall 1a of the annular groove 1, and the notch 2 consists of a bottom surface 2a and a wall surface 2b, and furthermore,
In a spool valve in which the wall surface 2b maintains an inclination angle α of 90 degrees or more with respect to the axis, an auxiliary notch 3 consisting of a hole whose tip is opened in the bottom surface 2a is formed, and the axis of the auxiliary notch 3 is A spool valve formed almost parallel to the wall surface 2b.