JPH01234676A - Valve device - Google Patents

Abstract

PURPOSE:To enhance the cavitation characteristic by making the angle of inclination of the one of two tapered peripheral surfaces formed in a valve element, which is adapted to be seated on a seat surface of a valve seat. CONSTITUTION:Two tapered peripheral surfaces 23a, 23b respectively having different angles theta1, theta2 of inclination and connected with each other are formed in a valve element 23 disposed on the axis of a seat ring 21 and adapted to control the opening and closing of a fluid passage 22. Of two these tapered peripheral surfaces, the one 23a adapted to be seated on a tapered seat surface 21a of the seat ring 21 has its angle theta1 which is set to be smaller than the angle theta2 of the other inclined peripheral surface 23b. With this arrangement, it is possible to delay occurrence of cavitation upon valve-opening.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a valve device that controls opening and closing of a fluid passage hole by raising and lowering a valve body.

[Conventional technology]

Various types of valve devices of this type have been known in the past, including a straight-through type shown in FIG. This will be explained based on the figure. In the figure, what is indicated by reference numeral 1 is a valve body that opens in three directions, and an inflow side compartment 3 and an outflow side compartment 4 are formed inside by a partition wall 2. ing. A ring mounting hole 5 opening in the axial direction is provided in the partition wall 2 of the valve body 1, and the ring mounting hole 5 has a valve seat having a fluid passage hole 6 communicating with the corner chambers 3 and 4. A seat ring 7 is fixed. Reference numeral 8 denotes an upper cover having an insertion hole 9 opening in the axial direction, and is fixed onto the valve body 1 with a star bolt 10 and a nut 11. Reference numeral 12 denotes a valve body for controlling opening and closing of the fluid passage hole 6, which is provided so as to be movable forward and backward on the axis of the seat ring 7, and is attached to a stem 13 that is inserted through the insertion hole 9. A guide ring 14 guides the valve body 12 and is fixed inside the valve body 1.

[Problem to be solved by the invention]

By the way, the sixth valve body in this type of valve device is
As shown in the figure, it is constituted by a valve body 15 provided with a seating portion 15a whose tapered peripheral surface has an inclination angle of θ,
Among these, the inclination angle θ of the taper circumferential surface is usually θ -30°, 45° because it improves the shutoff of fluid pressure when the valve is closed.
(The plane width t of the seating portion 15a is set to t=1 to 3 m).

In such a valve device, when the valve is opened, the arrow A in FIG.
, B, C, the valve body 15 or seat ring 1
It is known that the cavitation that occurs in the vicinity of 6 can be classified into three types depending on the location where it occurs, and that each cavitation occurs sequentially depending on the size of the valve opening (closed - open).

Here, if we pay attention to the cavitation that occurs in the direction of the arrow, the seating portion 15a is tilted at an angle of θ-3o°.

As can be seen from the experimental data graph shown in Figure 8, when the angle of inclination is 45°, cavitation is more likely to occur than when the angle of inclination is other than that; in other words, cavitation occurs when the differential pressure after the valve is low. -ing The figure shows the change in the initial value of cavitation depending on the inclination angle of the seating part 15a, and the vertical and horizontal axes represent the cavitation coefficient σ and the flow coefficient cd, and σ-(P2-P ν)/(PI-P2) .

cd=v,/,,7+2(p,-pz)/ρ+4-
■、2 There is.

However, Pl: Primary side pressure P2: Secondary pressure Pν: saturated vapor pressure ρ: fluid density vl is the flow velocity in the pipe.

Therefore, this type of valve device has poor cavitation characteristics, and has a low performance and service life as a valve.

In this case, the inclination angle θ of the seating portion 15a greatly affects the shutoff performance of the valve, and therefore the inclination angle θ is set to θ≧45.
It is virtually impossible to set the inclination angle θ to θ≦20°, and it is impossible to set the inclination angle θ to θ≦20°.
5a bites into the seat surface 16a of the seat ring 16 and does not operate smoothly.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a valve device that can improve the cavitation characteristics, thereby improving the performance and life of the valve.

[Means to solve the problem]

In the valve device according to the present invention, the valve body has an inclination angle θ1. θ2 and two connected taper circumferential surfaces are formed, and among these two taper circumferential surfaces, the inclination angle θ of the taper circumferential surface that is seated on the seat surface of the valve seat is smaller than the inclination angle θ2 of the other taper circumferential surfaces. It is set at an angle.

Further, in a valve device according to another invention, the valve seat has an inclination angle θ3. θ4 and two connected taper circumferential surfaces are formed, and among these taper circumferential surfaces, the inclination angle θ3 of the taper circumferential surface on which the valve body seating surface is seated is smaller than the inclination angle θ of the other taper circumferential surface. It is set at an angle.

[Function] In the present invention, the occurrence of cavitation when the valve is opened can be delayed by the two tapered circumferential surfaces each having an inclination angle different in size from each other.

〔Example〕

EMBODIMENT OF THE INVENTION Hereinafter, the structure etc. of this invention will be explained in detail by the Example shown in the figure.

Figure 1 (al and (bl) are a front view showing the main parts of the valve device according to the present invention and an enlarged view of the F part thereof. In the following figures, the same members as those in Figure 5 and members corresponding to these members are shown. are denoted by the same reference numerals, and detailed explanation will be omitted.
A seat ring serving as a valve seat has a fluid passage hole 22 that communicates with the outflow compartment 4 (shown in FIG. 5) and the outflow compartment 4 (shown in FIG. 5).
It is fixed in the ring attachment hole 5 (shown in FIG. 5), and a tapered peripheral surface 21a is formed at the open end as a seat surface on which a seating portion of a valve body, which will be described later, is seated. 23
is a valve body that controls opening and closing of the fluid passage hole 22, and is provided on the axis of the seat ring 21 so as to be movable forward and backward. This valve body 23 has an inclination angle θ2 that is different in size from each other.
．． two connected tapered peripheral surfaces 23a having θ2;
23b is formed. Of these tapered circumferential surfaces 23a and 23b, the tapered circumferential surface 23a seated on the tapered circumferential surface 21a of the sealing ring 21 has an inclination angle θ1.
is set to an angle smaller than the inclination angle θ2 of the other tapered surfaces 23b (for example, θ1-30° and θ2-60°). Further, the flow rate control portion 23c of the valve body 23 has a circumference set to a diameter of 44 mm, and each tapered peripheral surface 23a, 23b.
The maximum circumferences of are set to 46 mm and 4811, respectively. As a result, the tapered peripheral surfaces 23a, 2 (not shown in the figure)
3b plane width 1. ．． 12 is the dimension of LI+j2-1 dragon.

In the valve device configured in this way, two tapered circumferential surfaces 23a each having an inclination angle different in size from each other,
23b can delay the occurrence of cavitation when the valve is opened.

This can be understood from the graph shown in FIG. 2, and the cavitation characteristics of the valve device according to the present invention can be surely improved. Here, cavitation is P+ -4,0kgf/cn! abs, in the past, P2 = 1.8 kgf/cn! In the present invention, what is generated in abs is P2=0.8 kgf/
Colabs.

Moreover, in the present invention, two tapered surfaces 23a.

23b changes the streamline, and the flow rate characteristic curve changes to the third
As shown in the figure, it was possible to approach the ideal curve G and improve the flow characteristics.

In this embodiment, an example is shown in which two tapered surfaces 23a and 23b, each having a different size from the other, are formed on the valve body 23, but the present invention is not limited to this, and as shown in FIG. The valve seat 31 has tapered peripheral surfaces 31a and 31b.
Alternatively, both parts may have a tapered peripheral surface (
(not shown), the same effects as in the embodiment can be expected. In this case, the tapered peripheral surfaces 31a and 31b each have an inclination angle θ3. It has θ4 and is connected. Among these tapered peripheral surfaces 31a and 31b, a tapered peripheral surface 31a on which the seating surface 32a of the valve body 32 is seated.
The inclination angle θ3 is the inclination angle θ4 of the other tapered circumferential surface 31b.
The inclination angle is set to be smaller, and the planar width t3 of the tapered peripheral surface 31a is set to be smaller than the planar width t4 of the tapered peripheral surface 31b.

Further, in this embodiment, the inclination angle θ1. θ2 is set to θ1-30° and θ2-60°, and the plane width tl+j of the tapered peripheral surfaces 31a and 31b
2 is set to jl+j2 = i mm, but the present invention is not limited to this, and the tapered peripheral surfaces 31a, 31
The inclination angle θ4 of b. As long as θ2 satisfies the relationship θ1≦θ2, there is no problem in setting other inclination angles and plane widths. However, according to experiments, the tilt angle θ1.
θ is 20°≦θ1≦50°, 50'<θ2≦900,
θ2-θ, ≧5° is satisfied, and the plane width tI+t2 is 0
．． It is desirable that m≦(tl, t2) be satisfied.

〔Effect of the invention〕

As explained above, according to the present invention, the valve body has inclination angles θ1. 2 that has θ2 and is connected
The inclination angle θ1 of the taper circumferential surface that sits on the seat surface of the valve seat is set to be smaller than the inclination angle θ2 of the other taper circumferential surfaces, so that the valve can be opened. can delay the occurrence of cavitation.

Therefore, since the cavitation characteristics can be reliably improved, the performance and service life of the valve can be improved. Furthermore, the streamlines change due to the two tapered circumferential surfaces having different inclination angles, which has the advantage of improving flow characteristics.

[Brief explanation of the drawing]

Fig. 1 (a+ and b) is a front view showing the main parts of the valve device according to the present invention and an enlarged view of the F part thereof, Fig. 2 is the occurrence of cavitation due to the inclination angle of the tapered peripheral surface in the valve body of the present invention. Figure 3 is a diagram showing the flow rate characteristics, Figure 4 is a sectional view showing the main parts of the valve device according to the present invention and another invention, and Figure 5 is the entire conventional valve device. FIG. 6 is a cross-sectional view showing the main part of the valve body, FIG. 7 is a cross-sectional view showing how cavitation occurs, and FIG. 8 shows the initial occurrence of gearvitation due to the inclination angle of the taper circumferential surface in a conventional valve body. It is a diagram showing changes in values. 21...Seat ring, 22...Fluid passage hole,
23... Valve body, 23a, 23b... Tapered peripheral surface, θ8. θ2...Inclination angle.

Claims (2)

[Claims] (1) A valve seat (21) provided in the valve body and having a fluid passage hole communicating with an inflow-side compartment and an outflow-side compartment; In a valve device including a valve body (23) for controlling opening and closing of a passage hole, the valve body (23) has two connected tapered circumferential surfaces each having an inclination angle (θ_1) and (θ_2) different in size from each other. (23a, 23b), and the inclination angle (θ_1) of the taper peripheral surface (23a) that sits on the seat surface (21a) of the valve seat (21) among both tapered peripheral surfaces (23a) and (23b) is the inclination angle of the other taper circumferential surface (θ_
2) A valve device characterized by being set at a smaller angle. (2) In the valve device according to claim 1, the valve seat (31) has inclination angles (θ_3) and (θ_4) that are different in size from each other.
) and two connected tapered peripheral surfaces (31a), (
31b), and both tapered peripheral surfaces (31a), (
31b), the inclination angle θ_3 of the tapered circumferential surface (31a) on which the seating surface (32a) of the valve body (32) is seated is set to be smaller than the inclination angle θ_4 of the other taper circumferential surface (31b). valve device.