JPH0755415Y2 - Flow control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a flow rate control valve that proportionally changes the flow rate according to the stroke amount of a valve body.

(Prior Art) A flow control valve is used for blow-by gas recirculation of a crankcase of an automobile, intake of purge gas from a carbon canister, and the like, and is opened by receiving a negative pressure of intake air. Such a conventional valve is disclosed in, for example, Japanese Utility Model Laid-Open No. 61-6085, one example of which is shown in FIG. The valve element 31 is inserted into the valve case 30 and is pressed against the first valve seat 33 by the spring 32. The valve case 30 has a reduced diameter 34
Is provided to face the taper portion 35 of the valve body 31. Disc
The maximum stroke of 31 is restrained by the second valve seat 36, and the valve is closed at this position.

(Problems to be Solved by the Invention) The valve having the above structure is opened by negative pressure from the right side in FIG. It is difficult to accurately and proportionally adjust the minute flow rate when the negative pressure increases and the gap of the throttle portion 34 becomes smaller due to the movement of the taper portion 35. Therefore, a minute flow rate cannot be maintained at a relatively high negative pressure.

This is because the gap must be further narrowed when the pressure difference between the front and rear of the throttle becomes large due to a relatively high negative pressure. Because there is a limit.

(Means for Solving the Problems) In the flow control valve of the present invention, a first throttle portion facing the taper portion is provided on the inner wall of a valve case in which the valve body having the taper portion is arranged, and the valve body is provided. A second throttle portion is provided at a portion facing the tip end of the valve case so that the inner diameter of the valve case at this portion is reduced and the gap with the tip end of the valve body is narrowed.

(Operation) The gap between the first throttle portion and the taper portion of the valve body of the flow control valve of the present invention is narrowed as the negative pressure increases and the stroke of the valve body advances, which reduces the flow rate. Is. When the negative pressure increases and the valve body further advances, the tip portion of the valve body faces the position of the second throttle portion and throttles the flow rate. Therefore, the pressure difference between the front and rear of the valve element is shared by the first and second throttle portions, and the pressure difference is reduced in the first throttle portion even if the gap is the same as when the conventional second throttle portion is not provided. It is easy to fine-tune. Further, since the pressure difference in the second throttle portion is small, it is possible to maintain a minute flow rate as the entire valve. That is, even if the gap between the first and second throttles is about the same size as the conventional throttle, by using two stages in series, a gap with a smaller size than the conventional one with respect to the pressure difference before and after the valve body is created. It has the same effect as, and enables the proportional control of the minute flow rate at high negative pressure.

(Example) FIG. 1 shows an example. The flow control valve 1 includes a valve case 2, a valve body 3, and a spring 4. Valve case 2
Has a cylindrical shape, and one end of which has an inlet hole 5a at the center.
A first valve seat 5 having an outlet pipe 15 at the other end,
The hole of the outlet pipe 15 forms the outlet hole 15a. On the inner surface of the side wall of the valve case 2, a stepped portion 6, a first throttle portion 7 for partially reducing the inner diameter, and a second throttle portion 9 for further reducing the inner diameter are sequentially provided from one end side, and The second valve seat 8 is formed by the end surface of the second throttle portion 9 on the one end side of the valve case 2. The valve body 3 has a plunger shape, and the base end thereof has a first shutoff portion 11 facing the first valve seat 5, then a tapered portion 12 having a truncated cone shape, and a stepped portion on the small-diameter side end surface of the tapered portion 12. And a columnar tip portion 14 having a smaller diameter than the outer diameter of the cutoff portion 13, that is, the diameter of the end portion on the small diameter side of the taper portion 12, in that order. In the valve body 3, the tapered portion 12 faces the first throttle portion 7 of the valve case 2, and the tip portion 14 faces the second throttle portion 9,
It is arranged. The spring 4 is the tapered portion 12 of the valve body 3.
The first shutoff portion 11 having a slightly larger diameter and the one end surface of the first throttle portion 7 of the valve case 2 are arranged in a contracted manner, and the first shutoff portion 11 is connected to the first valve seat 5 Pressing against.

When a negative pressure is transmitted to the flow control valve 1 from the right side in the figure, the first cutoff portion 11 separates from the first valve seat 5 against the spring 4, and the fluid flows from left to right. When negative pressure becomes high, valve body 3
Goes to the right, and the gap between the tapered portion 12 and the first throttle portion 7 is gradually narrowed and the flow rate is relatively reduced. When the negative pressure is further increased, the gap between the first throttle portion 7 and the taper portion 12 is further narrowed, and at the same time, the tip portion 14 projects into the second throttle portion 9 to start the throttle action. Then, the pressure difference between the front and rear of the valve element due to the negative pressure is divided by the first and second throttle portions 7 and 9, so that the pressure difference between each is reduced. Therefore, the gap size is the same as when there is only one throttle portion. Even so, the flow rate is reduced, and the fine flow rate can be finely adjusted by advancing and retracting the stroke. This state is shown in the diagram X in FIG.
Indicate. Diagram Y shows the conventional state.

In FIG. 1, the tip portion 9 may be tapered, and the length of the valve element 3 may be changed so that the stepped portion 6 serves as a third valve seat and the rear surface of the first shutoff portion has a maximum stroke. At this time, the stepped portion 6 may be brought into contact with the second valve seat 8 and the second cutoff portion 13 shown in FIG.

Further, as in the example of FIG. 2, the small diameter portion of the tapered portion 22 of the valve body 23 is extended to form a cylindrical tip portion 24, and the tip end portion 24 is opposed to the inner surface of the side wall of the valve case 20. A cylindrical second throttle portion 29 is formed, and the tip end face of the valve body 23 is used as a second shutoff portion 25, and a stepped end face, that is, a bottom wall of the second throttle portion 29 is formed at the right end of the inner wall of the valve case 20. It may be seat 28.

(Effect of the Invention) The flow control valve of the present invention is provided with the first throttle portion and the second throttle portion, and the pressure difference is divided into two stages. A minute flow rate can be adjusted when a minute flow rate is to be achieved by pressure, and the desired valve performance can be obtained accurately.

[Brief description of drawings]

1 and 2 are sectional views showing an embodiment of the present invention and FIG. 3 is a sectional view showing a conventional product. FIG. 4 is a characteristic diagram of the flow control valve. 2, 20 ...... Valve case, 4 ...... Spring, 5 ...... First valve seat, 5a ...... Inlet hole, 7 ...... First throttle part, 8, 28 ......
2nd valve seat, 9, 29 ... 2nd throttle part, 12, 22 ... taper part, 15a ... exit hole, 14, 24 ... tip part

Claims (1)

[Scope of utility model registration request] 1. A first and a first cylindrical valve seat having an inlet hole at one end, and an inner diameter of the valve case reduced at two locations on an inner surface of a side wall of the valve case having an outlet hole at the other end. Two
Inside the valve case, in which the throttle portion is sequentially provided from one end side of the casing, a truncated cone-shaped tapered portion, a first cutoff portion formed on the large diameter side end surface of the tapered portion, and a small diameter side of the tapered portion. A plunger-shaped valve body composed of a tip portion continuing from the end face is arranged such that the large diameter side of the tapered portion is on the first valve seat side of the casing, and the tapered portion of the valve body faces the first throttle portion. At the same time, the tip of the valve body is opposed to the second throttle portion, and further, the spring is pressed in the gap between the valve case and the valve body, and the shutoff part of the valve body is pressed against the first valve seat of the valve case. The second valve seat, which is arranged so as to be contracted and closes the valve between the small diameter side end surface of the taper portion of the valve body or the tip end surface of the valve body, is the end surface of the second throttle portion on the inlet hole side or A flow rate control valve formed by the bottom wall of the hole of the second throttle portion.