JPH0114469B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a structure that reduces the fluid force acting on the spool in the direction of closing it due to oil flowing in and out when the auxiliary passage of the spool valve is opened.

Note that the above-mentioned auxiliary passage is used to include both the notch of the spool valve that forms a land and the oil hole of the hollow spool valve, but throughout this specification, both the notch and the oil hole are referred to. What is included is referred to as an auxiliary passage.

However, in order to reduce the fluid force, the applicant experimented by changing the position and shape of the auxiliary passage of the spool valve, and found that the present invention can significantly reduce the fluid force compared to the conventional one. found.

In order to logically elucidate the results of this experiment, in other words, the correlation between fluid force and the shape of the auxiliary passage, etc.
It is based on the following assumptions.

First, the fluid force F is found by equation ().

F=ρQVCosθ () where ρ is the weight per unit volume of hydraulic fluid, Q is the flow rate, V is the outflow velocity, and θ is the outflow angle with respect to the spool axis.

In equation (), if the opening area, the shape of the auxiliary passage, the amount of supplied oil, the type of supplied oil, the temperature, etc. are constant, ρQ is also constant.

Therefore, in order to clarify the above correlation, ρQ
may be constant, so that the expression ()
can be thought of as equation ().

Axial velocity component W = V Cosθ ... () Considering this equation (), when comparing the respective fluid forces, it is sufficient to compare this axial velocity component W, and in other words, the above outflow All you have to do is compare the angle θ.

However, in practice, it is difficult to theoretically elucidate this outflow angle θ.

Therefore, while observing the experimental process, the applicant
By estimating the oil outflow direction in each case and finding the outflow angle θ based on it, we were able to logically prove the correlation between the fluid force and the shape of the auxiliary passage.

On the premise of the above, FIG. 1 shows the correlation between the axial velocity component W of the notch shape as an auxiliary passage, that is, the fluid force F.

In this FIG. 1, A and B show the conventional one, and C to F show the first to fourth embodiments of the present invention. As is clear from this figure, there is a considerable difference in the axial velocity component W between the conventional one and the one of the present invention. explain.

In FIG. 1A, a notch a is formed at the ridge of the land 2 of the spool 1 along the axial cross section. In other words, this notch a maintains a relationship that coincides with the axis of the spool 1 and the center line of the end surface 3 of the land 2. And the bottom surface 4 of this notch a is
It is made to have a slight bulge while becoming shallower towards the land 2 circumference.

Now, when the notch a opens on the peripheral surface side of the land 2, the oil flows out in the direction of the arrow 5.

On the other hand, in FIG. 1B, the bottom surface 6 of the notch b is made at a right angle and its depth is deepened, and the other features are the same as in FIG. 1A.

Comparing both FIGS. 1A and 1B, the angle θ of the outflow direction 7 of the notch B, which has a vertical bottom and a deep pocket, is larger than that of the outflow direction 5 of the notch A.

This is because when the notch is made deeper, the oil flows out from the notch after flowing into the deeper notch, which inevitably increases the outflow angle θ.

The more I became deeply attached to Notsuchi, the more
The outflow angle becomes larger and the fluid force can be reduced.

However, the conventional notches shown in FIGS. 1A and B,
Since it is formed on the axial cross section along the diameter line of the spool, there is a limit to how deep it can be made. This is because in order to make the notch deeper than the one in Figure 1B, it would be necessary to cut into the neck 8 of the spool 1, which not only weakens the strength of the spool but also makes it difficult to work. This is because it is practically impossible.

Therefore, in the present invention, the notch serving as the auxiliary passage is formed with the axial section removed, thereby making the notch deeper.

Note that in the following description, when the term "axial section" is used, it refers to "the axial section along the diameter line of the spool."

In the first embodiment shown in FIG. 1C, a notch c is formed by cutting parallel to the axis from the end surface 3 of the land 2 of the spool 1 and across it.

Of course, as is clear from Fig. 3, this notch c is formed with the axial cross section removed, so it does not intersect with the neck 8, and its pocket relative to the opening on the land peripheral surface side is different from that of the conventional one. It gets deeper.

Therefore, the oil that has flowed into the opening on the land end face side of this notch c branches in two directions from the center of the notch c, and flows out from the opening on the land circumference side in the direction of arrow 9, but the outflow angle θ is The deeper it gets, the bigger it becomes.

In the second embodiment shown in FIG. 1D, as is clear from FIGS. 4 to 6, the land 2 of the spool 1
A notch d is formed by cutting from the end surface 3 of the cutting tool 10 at an angle α with respect to the axis.

Since the depth direction of the notch d is made oblique toward the shaft center as described above, the opening of the notch d on the land peripheral surface side is also oblique.

Since the land peripheral surface opening of the notch d is oblique, oil flows out along the opening in the direction of arrow 11. This outflow direction 11 is oblique to the axis, but in this case the angle θ of this outflow direction 11 with respect to the axis must be determined. This is because fluid forces acting in the axial direction are always a problem.

FIG. 4 shows this angle θ. That is, in this FIG. 4, the line gh indicates the axis line,
The outflow direction 11, that is, the line g-k is the axis gh
It rises by an angle θ ₂ from the line gi which is shifted by an angle θ ₁ in the horizontal direction.

Therefore, in Fig. 4, from point k to line gh
The angle kgl of the triangle gkl when a line k-l perpendicular to is drawn is the angle θ of the outflow direction 11 with respect to the axis. However, in the first embodiment, the above θ ₂ is the angle of the outflow direction with respect to the axis, so at least in this second embodiment, the angle θ of the outflow direction 11 with respect to the axis is larger than in the first embodiment, and the fluid force is increased accordingly. will decrease.

The third embodiment shown in FIG. 1E is similar to the first embodiment, but they differ in the following points. That is, in the first embodiment, the back wall 12 of the notch c is parallel to the land end surface 3, whereas in the third embodiment, the back wall 13 of the notch e is arc-shaped. .

By forming the back wall 13 into an arc shape as described above, the notch e becomes deeper, and the angle θ in the oil outflow direction 14 increases accordingly.

The notch f of the fourth embodiment shown in FIG. 1F is similar to the second embodiment, but the back wall 15 of the notch f is shaped like an arc, unlike the back wall 16 of the second embodiment.

Therefore, the outflow direction 17 is smaller than that in the second embodiment.
The angle θ becomes even larger.

It should be noted that each of the notches in the first to fourth embodiments described above is of course formed by removing the axial cross section and crossing the land end face, but a plurality of such notches are required, and they are formed on the circumference of the land end face. Equal spacing in direction must be maintained.

7 and 8 show a fifth embodiment, and FIGS. 9 and 10 show a sixth embodiment. In these fifth and sixth embodiments, the spool 21 is hollow, and oil holes are used as oil inflow and outflow passages. 22 and 23 are formed.

The oil holes 22 and 23 serve as both the auxiliary passage of the present invention and the main passage of the spool.

However, in the fifth embodiment, the pair of oil holes 22
was formed immediately after removing the axial section.

Since the oil hole 22 is formed by removing the shaft cross section as described above, the length n' of the oil hole 25 is longer than the length n' of the oil hole 25 when the oil hole is formed along the shaft cross section as shown in FIG. The length n of the hole 22 is longer. The longer the oil hole is, the stronger the vertical guiding force becomes, and the more the outflow direction 24 rises,
The angle θ also becomes larger.

Also in the sixth embodiment, the oil hole 23 is formed by removing the axial cross section, and is bent outward to maintain the angle β with respect to the tangent to the spool. The oil hole 23 also maintains an angle δ with respect to the axis.

Therefore, according to this sixth embodiment, the oil hole 23
Not only is the length of the oil hole 22 of the fifth embodiment longer than that of the oil hole 22 of the fifth embodiment, but since the angle δ is maintained, the hole is deeper, and the angle θ in the outflow direction 26 is also further increased.

Note that the oil holes 22 and 23 in the fifth and sixth embodiments are as follows:
A plurality of each oil hole must be formed and each oil hole must be located at equal intervals.

Further, in the fifth and sixth embodiments described above, one oil hole serves as both the auxiliary passage and the main passage, but they are formed separately, and only the oil hole serving as the auxiliary passage is used as explained in the above embodiment. Of course it's a good thing.

As is clear from the above description, according to the fluid force reduction structure of the present invention, since the auxiliary passage is formed with the axial section removed, the auxiliary passage can be formed deeply.

Since the auxiliary passage can be formed deeply in this manner, the outflow angle of the fluid flowing out from the auxiliary passage can be increased accordingly. Therefore, the fluid force when the auxiliary passage opens can be reduced, and the operability of the spool is improved accordingly.

[Brief explanation of drawings]

Figure 1 of the drawing shows the relative difference in velocity components in the axial direction.
Figures C to F show the first to fourth embodiments of the present invention, Figure 2 is a perspective view of the conventional one, Figure 3 is a perspective view of the first embodiment, and Figures 4 to 6 show the second embodiment. 4 is a perspective view, FIG. 5 is a plan view, FIG. 6 is a side view also showing the cutting tool for forming the notch, and FIGS. 7 and 8 are views of the fifth embodiment. An end view of the spool and a sectional view taken along the line 7 in FIG. 7, and FIGS.
11 is an end view of a conventional spool. 1, 21...Spool, c to f and 22, 23
...Notches and oil holes that are auxiliary passages of this invention,
13, 15...The back wall of Notsuchi.

Claims (1)

[Claims] 1. In a spool valve that has a plurality of auxiliary passages through which a small amount of oil flows until the spool is completely opened, the auxiliary passages are removed from the axial cross section along the diameter line of the spool, and each of the auxiliary passages is a fluid force reduction structure of spool valves spaced at equal intervals in the circumferential direction of the spool.