JPH0552467U - Gate valve actuator - Google Patents

Abstract

(57) [Summary] [Purpose] Even if the valve shaft expands or contracts due to significant fluctuations in ambient temperature, the function of the valve is not hindered. [Structure] A long stem nut (11) is screwed on the lower part of the valve shaft (3), and a worm wheel (12) rotated by a motor via a worm (14) is installed on the lower part of the stem nut (11). , A compression spring (20) that is slidably fitted in the non-rotatable axial direction by a spline connection (13) and presses the buffer cylinder (17) downward in the valve box (2). It corresponds to the expansion and contraction of 3).

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an actuator that prevents the function of a valve from being hindered even when the valve shaft expands or contracts due to a significant change in temperature around the gate valve.

[0002]

[Prior Art]

 Fig. 2 shows the main part of a conventional gate valve. The valve shaft (3) whose lower end is fixed to the valve body (1) and penetrates the valve box (2) has a vertically long guide groove cut on the side surface. The valve (4) fits into the detent (5) formed in the valve box (2), and is lifted and lowered by the actuator (A) as described below installed on the outer upper part of the valve box (2), Open and close.

A stem nut (6) is screwed onto the upper portion of the valve shaft (3), and the stem nut (6) is held by upper and lower bearings (7) so that the valve nut (2) cannot rotate up and down. Supported by.

A worm wheel (8) is fitted on the stem nut (6), and a worm (9) meshing with the worm wheel (8) is rotated in both directions by a motor (10). The valve body (1) rises together with the valve shaft (3) by the rotation of the motor (10) to open and close the gate valve.

[0005]

[Problems to be solved by the device]

 However, since the long valve shaft (3) of the gate valve expands and contracts due to changes in ambient temperature, in the conventional gate valve, the valve box (3) contracts when the valve closed under high temperature in hot weather becomes cold at night. , The valve may open slightly.

Further, when the valve closed at night during cold weather becomes hot during the daytime, the valve shaft (3) may extend and damage the member of the actuator (A). The present invention has been made for the purpose of solving these problems.

[0007]

[Means for Solving the Problems]

 According to the present invention, a worm wheel of a worm gear is provided on the valve shaft by screwing a system nut longer than the stem nut (6) of the conventional actuator (A), and the lower part of the stem nut is rotated by an appropriate drive device. Non-rotatable axially slidable external fitting, a shock absorber cylinder is movably connected to the upper end of the stem nut so as to be slightly movable in the axial direction, and a compression spring that presses the shock absorber cylinder downward in the valve box. By providing the above, the above-mentioned problems are solved.

[0008]

[Action]

 In the gate valve to which the present invention is applied, when the stem nut rotates together with the worm gear, the valve body moves up and down together with the valve shaft to open and close the valve, similar to the conventional gate valve.

When the valve body is located at the upper limit or the lower limit, if the long valve shaft expands or contracts slightly due to temperature change, the stem nut expands or contracts the compression spring to accommodate the movement of the buffer cylinder. The valve body is constantly pressed with an appropriate pressure in the closing direction to prevent the closing valve from opening and the members from being damaged.

[0010]

【Example】

 FIG. 1 shows an embodiment of the present invention. The same members as those of the above-mentioned conventional actuator (A) are designated by the same reference numerals and the description thereof will be omitted. The valve shaft (3) is moved up and down by an actuator (B) of the present invention installed on the valve box (2) as described below to open and close the valve.

A stem nut (11) longer than the above (6) is screwed onto the valve shaft (3), and a worm wheel (12) is connected to the stem nut (11) by a spline connection (13). Non-rotatable fits in the vertical movement.

The worm (14) meshing with the worm wheel (12) is rotated in both directions by a motor (not shown), and the worm wheel (12) is laterally moved to the valve box (2) by the bearing (15). It is imperatively supported.

A shock absorbing cylinder (17) is fitted onto the upper part of the stem nut (11) through a bearing ring (16), and the shock absorbing cylinder (17) is provided above and below the inner upper part of the valve box (2). Due to the gap (18), it is fitted so that it can move up and down slightly.

A coil-shaped compression spring (20) is provided inside an annular groove (19) cut in the upper surface of the buffer cylinder (17) and the opposing surface of the valve box (2). In the actuator (B), when the stem nut (11) rotates together with the worm wheel (12), the valve body (not shown) moves up and down together with the valve shaft (3) to open and close the valve.

When the valve body is located at the upper limit or the lower limit and the valve shaft (3) expands or contracts slightly due to temperature change, the stem nut (11) together with the buffer cylinder (17) falls within the range allowed by the gap (18). Although it goes up and down slightly, the worm wheel (12) that is splined with the stem nut (11) does not go up and down.

However, since the amount of vertical movement of the stem nut (11) is small, the valve shaft (3) can be raised and lowered without hindrance, and members such as the worm (14) and the worm wheel (12) are not damaged. ..

Even when the valve shaft (3) is shortened, the compression spring (20) pushes down the valve shaft (3) via the buffer cylinder (17) and the stem nut (11), so that the valve is closed. No leaks will occur.

[0018]

[Effect of the device]

 As described above, in the actuator of the present invention, when the valve body is located at the upper limit or the lower limit because the compression spring constantly presses the stem nut, which can be moved up and down slightly, with appropriate pressure through the buffer cylinder. Even if the valve shaft expands or contracts slightly due to temperature changes, leakage does not occur in the closed valve and members such as the stem nut and worm gear are not damaged or damaged.

[Brief description of drawings]

FIG. 1 is a central vertical front view of an actuator of the present invention.

FIG. 2 is a central vertical sectional front view of a conventional actuator.

[Explanation of symbols]

 (A) (B) Actuator (1) Valve body (2) Valve box (3) Valve shaft (4) Guide groove (5) Anti-rotation (6) Stem nut (7) Beering (8) Worm wheel (9) Worm (10) Motor (11) Stem nut (12) Worm wheel (13) Spline connection (14) Worm (15) (16) Bayer ring (17) Buffer tube (18) Gap (19) Annular groove (20) Compression spring

Claims (1)

[Scope of utility model registration request] 1. A long stem nut is screwed on a valve shaft of a gate valve, and a worm wheel of a worm gear which is rotated by an appropriate driving device is slidably mounted on a lower portion of the stem nut in a non-rotatable axial direction. A gate valve, which is fitted externally, is provided with a shock absorber cylinder at the upper end of the stem nut so as to be movable, and is slightly movable in the axial direction, and a compression spring for pressing the shock absorber cylinder downward is provided in the valve box. Actuator.