JPH1047501A - Gate valve - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To allow foreign substances to be smoothly discharged to the downstream side by the flow of fluid itself even at a small flow rate with a small valve opening, and to minimize the occurrence of fluid leakage when fully closed. It can be so. SOLUTION: An axis x of a fluid flow path 2 formed in a valve box 1 is provided.
The valve rod 3 is slid in the vertical direction with respect to the valve rod 3 so that the seat 7a of the valve body 7 fixed to the tip of the valve rod 3 is brought into contact with and separated from the seat 8 formed on the outer periphery of the fluid flow path 2. Thereby, in the gate valve configured to open and close the fluid flow path 2,
The fluid passage 2 in the valve box 1 has an oval shape in vertical cross section, and a reduced passage portion 2A having a reduced sectional area is formed below the passage 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sluice valve used for sewage or agricultural water piping, for example. The present invention relates to a gate valve that opens and closes a flow path or changes a flow path area by sliding in a direction.

[0002]

2. Description of the Related Art FIG. 3 is a view generally used in the past, and is a semi-longitudinal front view of a flange type external threaded gate valve specified in JIS, and FIG.
In each of these drawings, reference numeral 1 denotes a valve box in which a fluid flow path 2 having a circular vertical cross section is formed linearly, and fluid pipes are provided at both ends of the fluid flow path 2 in the direction of the axis x. (Not shown), flange portions 2a, 2a connectable to each other are formed. Reference numeral 3 denotes a valve cover 4 fixed to an upper portion of the valve box 1 and a cylinder 5 fixedly connected to an upper end portion of the valve cover 4 in a vertical posture perpendicular to the axis x of the fluid flow path 2. The valve shaft is rotatably supported and has an external thread portion 3a formed on the outer peripheral surface thereof. It is configured to be slidable up and down with rotation.

An opening / closing valve element 7 is fixedly connected to the lower end of the valve rod 3 and contacts a seat portion 8 formed on the outer periphery of the fluid flow path 2 as the valve rod 3 slides up and down. It has a substantially arc-shaped seat portion 7a that comes in contact with and separates from the seat portion, and when the valve is closed, fluid leakage is prevented by metal touch between the seat portion 8 on the valve box 1 side and the seat portion 7a on the valve body 7 side. Have been.

[0004]

In the conventional gate valve having the above-described structure, the leakage at the time of closing the valve box 1 occurs.
Is determined by the quality of the rubbing accuracy of the contact surface between the seat portion 8 on the side and the seat portion 7a on the valve body 7 side. The deposited foreign matter tends to accumulate near the upstream of the contact surface of the sheet 7a, and this accumulated foreign matter is caught between the sheet portions 8, 7a, causing fluid leakage when the sheet is fully closed. In particular, since the fluid flow path 2 has a circular vertical cross-sectional shape, the water level does not rise at a small flow rate with a small valve opening, and it is difficult to sufficiently exert the function of discharging foreign substances downstream by the flow of the fluid. There is a problem that a fluid leak easily occurs due to the accumulation of foreign matter.

Accordingly, the present invention has been made in view of the above circumstances, and foreign substances can be smoothly discharged downstream by the flow of the fluid itself even at a small flow rate with a small valve opening.
It is an object of the present invention to provide a gate valve that can minimize the occurrence of fluid leakage when fully closed.

[0006]

According to a first aspect of the present invention, there is provided a gate valve having a fluid passage therein and a valve having a fluid passage therein. A valve stem slidable in the vertical direction perpendicular to the axis, and a valve fixed to the tip of the valve stem and abutting against a seat formed on the outer periphery of the fluid flow passage by sliding the valve stem in the vertical direction. A gate valve having an opening / closing valve body having a separated seat portion, characterized in that a reduced channel portion having a cross-sectional area is formed below a fluid channel in the valve box. By synergistically increasing the water level at a low flow rate with the valve slightly opened, and increasing the flow velocity by reducing the cross-sectional area of the flow path, the foreign substances contained in the fluid can be flowed by the fluid itself. It is possible to discharge to the downstream side, so that there is almost no accumulation of foreign matter. , The occurrence of fluid leakage due to the fully closed foreign matter is caught between both seat can be prevented as much as possible.

[0007] In particular, if the fluid flow path in the valve box is formed in an oval shape in a vertical sectional shape, and the reduced flow path portion is formed with its small diameter side,
Since there is no angularity in the reduced flow path portion, the discharge of the foreign matter to the downstream side at a small flow rate is further smoothed, and the function of preventing fluid leakage can be enhanced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a semi-longitudinal front view of a gate valve according to the present invention. As is apparent from FIG. 1, a fluid flow passage 2 formed inside a valve box 1 has an oval longitudinal cross-sectional shape. By forming the flow path 2 such that the large diameter side is located at the upper part and the small diameter side is located at the lower part, the lower part of the fluid flow path 2 is a reduced flow path part 2A having a reduced sectional area. Since the entire configuration of the gate valve is as shown in FIGS. 3 and 4, in FIG. 1, the same parts as those of the conventional gate valve shown in FIGS. Description is omitted.

In the gate valve configured as described above,
When the valve 7 is slightly opened and the flow rate is small, the water level in the reduced flow path 2A rises, and the cross-sectional area of the flow path is reduced, so that the flow velocity of the fluid flowing in the reduced flow path 2A increases.
Due to the synergistic effect of the rise in water level and the increase in flow velocity,
Foreign matter contained in the fluid is smoothly discharged downstream with the flow of the fluid itself, whereby the foreign matter hardly accumulates near the upstream of the contact surfaces of the sheet portions 8, 7a. When the sheet is completely closed, foreign matter is
This prevents the occurrence of fluid leakage due to being caught between the a and 8.

[0010] In the above embodiment, the whole of the fluid flow path 2 has an oval longitudinal cross section.
In addition to this, for example, as shown in FIG. 2, even when a reduced cross-section 2 </ b> A having a substantially U-shaped vertical cross-section is formed to communicate with a lower portion of the main fluid flow path 2 having a circular vertical cross-section, It is possible to exhibit the same foreign matter discharging function as in the above embodiment.

[0011]

As described above, according to the present invention, by forming the reduced flow path portion below the fluid flow path, it is possible to raise the water level at a small flow rate with a small valve opening degree, By the synergistic action of reducing the cross-sectional area and increasing the flow velocity, foreign substances contained in the fluid can be smoothly discharged to the downstream side with the flow of the fluid itself. Foreign matter is deposited near the upstream side of the contact surface with the valve box side seat portion, and it is possible to minimize the occurrence of fluid leakage due to the deposited foreign matter being caught between the two seat portions when fully closed. To play.

In particular, in the case where the fluid flow path is formed in an oval shape in vertical cross section, since the reduced flow path portion does not have a square shape, the discharge of foreign matter to the downstream side at a small flow rate is made smoother. The function of preventing fluid leakage can be enhanced.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing an open state of a gate valve according to the present invention.

FIG. 2 is an enlarged vertical sectional front view of a main part showing another embodiment of the present invention.

FIG. 3 is a semi-longitudinal front view of a conventionally used gate valve.

FIG. 4 is a semi-longitudinal side view of the gate valve;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve case 2 Fluid flow path 2A Reduction flow path part 3 Valve stem 7 Valve body 7a Valve body side seat part 8 Valve box side seat part

Claims (2)

[Claims] 1. A valve box having a fluid flow path therein, a valve rod slidable in a vertical direction perpendicular to an axis of the flow path in the valve box, and fixed to a tip of the valve rod. An opening / closing valve body having a seat portion which comes into contact with and separates from a seat portion formed on the outer periphery of the fluid flow passage by sliding the valve stem in the vertical direction; A gate valve having a reduced flow passage section having a reduced cross-sectional area formed at a lower portion of a passage. 2. The gate valve according to claim 1, wherein the fluid passage in the valve box has an oval shape in a vertical cross-sectional shape, and the reduced passage portion is formed by a small diameter side thereof.