JPH0552466U - Control valve drive - Google Patents

Abstract

(57) [Abstract] [Purpose] The guide bearing of the rod that moves up and down together with the diaphragm of the control valve drive that pneumatically operates the automatic control valve is made movable to eliminate the bias load applied to the rod and seal the diaphragm chamber. The purpose is to retain sex. [Structure] A center hole of a yoke is formed on the outer circumference of a guide bearing that holds a rod that moves up and down by being fixed to a diaphragm, and a collar that fits an O-ring for sealing in a ring groove and fixes this to the valve body. It is configured by movably fitting in a groove provided on the inner circumference.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a guide bearing that supports a core shaft of a pneumatic drive unit that drives an automatic control valve or the like used in the field of process control, for example.

[0002]

[Prior Art]

 As a device for automatically remotely controlling and opening and closing various valves such as an automatic control valve, there is a device as shown in FIG. This device is a diaphragm-type valve drive device that vertically moves a valve shaft that is integrally connected to a rod of a diaphragm by applying a pressure displacement to the diaphragm by air pressure applied to the pressure chamber.

The control valve drive device in FIG. 6 is fixed to a yoke A, and a diaphragm case B whose inside is divided into an upper chamber C1 and a lower chamber C2 by a diaphragm D, and between the diaphragm D and the diaphragm case B. Interposed coil spring G, a guide bearing H that holds the drive shaft vertically movable at the center of the diaphragm case B, and a guide bearing H that supports the guide shaft H and fixes the upper end to the diaphragm D and the lower end. It is composed of a drive shaft protruding outside the diaphragm case B and protruding to the center of the yoke A, and an automatic control valve and the like are operated by compressed air.

That is, a diaphragm fixed to the upper portion of a yoke A that is fixed to the valve body to be controlled. A disc-shaped diaphragm D that defines an upper chamber C1 and a lower chamber C2 in a diaphragm case B is provided at the center of the valve shaft of the valve body. The upper end of the rod F connected to E is screwed, and the coil spring G is urged to the upper part of the diaphragm D, and the rod F moves up and down on the guide bearing H integrally fixed to the center of the yoke A together with the diaphragm case B. It has a structure that allows it to move freely. J is an upper stopper which is fastened together with the diaphragm D to regulate the upper limit of the rod F, and K is a lower stopper. Further, the rod F and the yoke A are provided with a pointer L for displaying the degree of opening and closing of the valve body and a scale plate M.

[0005]

[Problems to be solved by the device]

 In the conventional valve drive device configured as described above, the rod F of the diaphragm D is concentrically connected to the valve shaft E of the valve body and assembled, and is added to the lower lower chamber C 2 of the diaphragm D. The diaphragm D, the diaphragm plate I, the rod F, and the valve shaft E are united by the air pressure, and the vertical movement is repeated, and the valve seat of the valve body is accurately held, so that the reliability of the process control can be obtained. .. In this case, the airtightness of the lower chamber C2 that holds the air pressure for operating the diaphragm D is an essential requirement.

In order to correctly move the valve shaft E of the valve body up and down, it is also an important point to ensure that the shaft center of the rod F of the valve drive device and the shaft center of the valve shaft of the valve body are aligned. However, in order to accurately center the shaft, the valve body uses its own method to center the valve shaft, and the center of the bonnet of the valve body and the yoke A of the valve drive unit is centered.

In the above-mentioned conventional example, the guide bearing H that supports the rod F of the diaphragm D is fixed by welding the outer circumference to the diaphragm case B and integrated, so that the rod F always attaches the diaphragm D downward. The biasing coil spring G is twisted and the valve shaft E of the valve body is subjected to a bending stress in the joint portion due to the misalignment of the valve shaft E, so that a biasing force is applied to the guide bearing H.

Further, the guide bearing H has a function of holding the airtightness of the lower chamber C2, which is an absolute requirement for holding the air pressure, and a role of holding the vertical axis of the rod F, but on the other hand, it is fixed to the case portion B2 of the diaphragm case B. Therefore, there is a defect that the airtightness is impaired due to the uneven wear, and the durability is weak.

[0009]

[Means for Solving the Problems]

 The present invention has been devised to solve the above problems, and has the following means. The first invention to receive registration is a diaphragm case that is fixed to a yoke and is divided into upper and lower parts by a diaphragm, a coil spring interposed between the diaphragm and the diaphragm case, and a center of the diaphragm case. A guide bearing that holds the drive shaft so that it can move up and down, and a drive that is supported by this guide bearing, the upper end is fixed to the diaphragm, and the lower end projects outside the diaphragm case and projects into the center of the yoke. In a control valve drive device that is composed of a shaft and operates an automatic control valve etc. with compressed air, the above guide bearing holds the drive shaft that moves up and down in conjunction with the movement of the diaphragm, and also follows the deviation of the drive shaft. In this way, the guide bearing is made movably. Even if the coil spring twists due to the guide bearing being movable, the valve seat of the valve body can be held accurately without applying a biasing force to the valve shaft, and the air pressure can be kept tight. Can be secured.

A second invention for receiving registration is a more specific configuration of the guide bearing of the above-mentioned first invention, in which a flange portion in which an O-ring is fitted is formed on the outer peripheral portion thereof. A guide tube that serves as a guide through hole is fitted to the inner peripheral part, a seal packing is fitted to the upper inner peripheral part of the guide through hole, and a grease reservoir and a dust seal are fitted to the lower inner peripheral part of the guide through hole. It is provided so that the guide bearing can be made to follow the displacement of the drive shaft. The above guide bearing ensures sufficient airtightness by an O-ring, seal packing, grease reservoir, etc., and allows the guide bearing to move and follow even if the downwardly biased coil spring is twisted. The valve seat of the valve body is accurately held without applying a biasing force to the valve shaft.

[0011]

[Action]

 The guide bearing works smoothly with the valve shaft in response to the vertical movement of the rod, has the role of reducing reciprocal hysteresis, and has the function of sealing the air pressure supplied to the lower chamber. It is an important part that influences. The guide bearing of the present invention is not fixed to the diaphragm case and can move freely according to the shaft center. The guide bearing is sealed with the diaphragm case by the O-ring in the ring groove provided in the flange on the outer circumference of the main body. Ensure the air pressure supplied to the chamber is sealed. The groove into which the flange fits can respond to the movement of the guide bearing that moves with the left and right swing in the circumferential direction when the rod moves up and down.

The seal packing prevents leakage from the inner longitudinal contact portion between the rod and the guide bearing, and the guide tube facilitates vertical sliding of the rod, while at the same time ensuring the smoothness by the grease in the grease reservoir, The dust seal prevents grease from leaking and prevents dust from adhering to the portion of the rod exposed to the atmosphere from the outside, or foreign matter from entering the guide bearing when the rod is raised. Therefore, the workability such as the distortion of the diaphragm case and the centering work with the diaphragm case is much better than that of the conventional welding and fixing, and the durability can be improved by an order of magnitude.

[0013]

【Example】

 Next, an embodiment of the present invention will be described. FIG. 1 is a front view showing a part of the present invention cut away, FIG. 2 is a plan view of the same, FIG. 3 is a sectional view of an essential part, and FIG. 4 is a guide. FIG. 5 is an enlarged sectional view of the bearing, and FIG. 5 is a sectional view for normal operation using the control valve driving device according to the present invention.

The valve drive device in the above drawings comprises a U-shaped yoke 1 fixed to a valve body, and a disc-shaped hollow die which is vertically divided into an upper end flange portion of the yoke 1. The flam case 2 is fixed. The diaphragm case 2 is composed of an upper cover and a case portion, and is hermetically joined by a plurality of bolts 3, 3, .... A diaphragm-shaped diaphragm 4 fastened together with bolts 3, 3, ... Is provided inside the diaphragm case 2, and the case 2 is partitioned into an upper chamber 2a and a lower chamber 2b. Then, the upper end of a rod 6 which is vertically movably fitted to a guide bearing 5 is fixed to the center of the diaphragm 4 by a nut 7 which is screwed into its threaded portion.

Reference numeral 8 is a U-shaped upper stopper that is fastened together with the diaphragm 4 and regulates the upper limit of the rod 6, and 9 is a U-shaped lower stopper that is also fastened together with the diaphragm 4 and restrains its movement. Further, between the diaphragm 4 and the upper stopper 8 is inscribed in the diaphragm 4 and holds a plurality of coil springs 10, 10, ... There is.

Reference numeral 12 is a spring receiving plate for positioning the coil spring 10. The spring receiving plate 12 is fixed to the diaphragm plate 11, and the diaphragm 4 is urged downward by the coil spring 10. A compressed air supply port is opened in the lower chamber 2b of the diaphragm case 2. The rod 6 is connected via a coupling to a valve shaft 13 that opens and closes the valve seat of the valve body to be controlled by vertical movement, and the rod 6 and the yoke 1 are provided with a pointer 14 that indicates the degree of opening and closing of the valve. A scale plate 15 is provided. When compressed air is supplied to the lower chamber 2b of the diaphragm case 2, the pressure causes the diaphragm 4 to displace against the elastic force of the coil spring 10 and the valve shaft 13 together with the rod 6 integrated with the diaphragm 4. Rises and a predetermined valve opening is obtained. The valve opening at this time is displayed on the scale plate 15 and the pointer 14. The above is the operating principle of the reverse-acting valve drive device, but the forward-acting valve drive device shown in FIG. 5 operates similarly.

Next, the guide bearing 5 provided at the center of the diaphragm 4 will be described. The guide bearing 5 has a flange portion 18 projectingly formed on its outer peripheral portion, and a ring groove 18 a is formed on the upper peripheral surface of the flange portion 18. An O-ring 19 is fitted in the ring groove 18a. A guide through hole is formed in the inner peripheral portion of the guide bearing 5 to fit the rod 6 vertically and automatically. The guide tube 20 is fitted inside the guide through hole. A seal packing 21 is fitted in the portion. Further, a grease reservoir 22 and a dust seal 23, in which a grease 22a is filled, are provided on the lower inner peripheral portion of the guide through hole.

On the other hand, in the upper end flange portion of the yoke 1, a concave groove 17 is formed in the center portion of the center hole into which the guide bearing 5 is fitted. The concave groove 17 is formed in the concave groove 17. The collar portion 2 is adapted to fit. Then, when the yoke 1 and the diaphragm case 2 are fixed, the O-ring 19 fitted in the ring groove 18a of the collar portion 18 abuts the bottom surface portion of the diaphragm case 2 to seal the lower chamber 2b of the diaphragm case 2. Sex is certain.

Accordingly, the guide bearing 5 is provided in the groove 17 of the collar 18 in response to the core misalignment between the valve body and the valve shaft, the vertical movement of the rod 6, and the slight movement of the rod shaft core due to the twisting of the coil spring 10. Fine movements are adjusted to eliminate the biased force due to bending stress. Then, the lower chamber 2b under the diaphragm, which is sealed by the O-ring 19 of the collar 18 and to which air pressure is applied, is securely sealed and held. The seal packing 21 prevents air pressure from leaking from the inner diameter contact portion of the rod 6, and the dust seal 23 prevents dust and foreign matter from entering the rod 6, and the grease 22a in the grease reservoir 22 prevents the rod 6 from sliding. Be smoothed.

Therefore, compared to the conventional structure in which the guide bearing is welded and fixed to the diaphragm case, workability in centering work, leakage prevention, and durability are significantly improved. In the test, air leaked from the inner diameters of the rod and the guide bearing after 100,000 to 300,000 times, and the durability increased over 500,000 times, the leakage increased so as to affect the performance of the control valve. The performance of the control valve did not change at all even after a durability test of over 1 million times, and a large effect could be confirmed. Note that the number of coil springs is not limited to one, and the same effect can be obtained with one coil spring.

[0021]

[Effect of the device]

 As described above, in the present invention, in a control valve drive device for operating an automatic control valve or the like with compressed air, a guide bearing holds a drive shaft that moves up and down in conjunction with the movement of a diaphragm, and the drive shaft shifts. Following this, the guide bearings were made to be mobile. Therefore, when the air pressure is applied to the lower chamber due to the introduction of the supply air pressure and the diaphragm, the diaphragm plate, and the integrally connected rod are lifted against the coil spring, the plane of the diaphragm plate generated by the directionality of the elastic force of the coil spring is increased. The variation of the spring force received gives a horizontal left and right torque to the rod in the horizontal direction, and at the same time, a left and right circumferential torque acts on the guide bearing as the rod slides up and down. The inner circumference and the collar follow the fine movements of the rod to reduce the torque on the left and right sides of the circumference, the axial center of the rod and the valve shaft are matched, and the seal is secured and the air pressure is maintained. The operation of the shaft is ensured, and the valve seat can be held accurately.

Further, in the movable guide bearing, a flange portion in which an O-ring is fitted is formed on an outer peripheral portion thereof, a guide tube serving as a guide through hole is fitted on an inner peripheral portion, and the guide through hole is formed. A seal packing is fitted on the upper inner peripheral part of the guide through hole, and a grease reservoir and a dust seal are provided on the lower inner peripheral part of the guide through hole, so that followability and hermeticity are further ensured.

[Brief description of drawings]

FIG. 1 is a front view showing a partially cutaway view.

FIG. 2 is a plan view.

FIG. 3 is a sectional view of a main part.

FIG. 4 is an enlarged cross-sectional view of a guide bearing.

FIG. 5 is a cross-sectional view for normal operation using a control valve drive device.

FIG. 6 is a cross-sectional view of a conventional drive device.

[Explanation of sign]

 1 Yoke 2 Diaphragm Case 4 Diaphragm 5 Guide Bearing 6 Rod 10 Coil Spring 17 Groove 18 Collar 19 O-ring 21 Seal Packing 22 Grease Reservoir 23 Dust Seal

Claims (2)

[Scope of utility model registration request] 1. A diaphragm case which is fixed to a yoke and whose inside is divided into upper and lower parts by a diaphragm, a coil spring interposed between the diaphragm and the diaphragm case, and a drive shaft which is vertically movable at a central portion of the diaphragm case. And a guide bearing to be supported by this guide bearing,
A control valve drive device comprising a drive shaft having an upper end fixed to a diaphragm and a lower end protruding outside the diaphragm case and protruding into the center of the yoke, wherein the automatic control valve or the like is operated by compressed air. The control valve driving device is characterized in that the guide bearing of (1) holds a drive shaft that moves up and down in conjunction with the movement of the diaphragm, and that the guide bearing is made movable in accordance with the displacement of the drive shaft. 2. The movable guide bearing has a flange portion in which an O-ring is fitted on an outer peripheral portion thereof, a guide tube serving as a guide through hole is fitted on an inner peripheral portion, and the guide through hole is provided. A seal packing is fitted on the upper inner peripheral part of the guide through hole, and a grease reservoir and a dust seal are provided on the lower inner peripheral part of the guide through hole to allow the guide bearing to be movable following the deviation of the drive shaft. The control valve drive device according to claim 1, wherein the control valve drive device is provided.