US2925987A - Diaphragm valve with yieldable connections between the diaphragm, stem, and valve hea - Google Patents

Description

Feb. 23, 1960 c H. PRIESMEYER 2,925,987

DIAPHRAGM VALVE YIELDABLE CONNECTIONS BETWEEN THE DIAPHRAGM, STEM, AND VALVE HEAD Filed Aug. 28, 1957 United States Patent DIAPHRAGM VALVE WITH YIELDABLE CON NECTIONS BETWEEN THE DIAPHRAGM, STEM, AND VALVE HEAD Charles Hansen Priesmeyer, Wilmette, 111., assignor to The Powers Regulator Company, Skokie, 111., a corporation'of Illinois Application August 28, 1957, Serial No. 680,737

8 Claims. (Cl. 251--61) This invention pertains to control valves and in particular to control valves that are used in conjunction with air conditioning systems.

In air conditioning systems the control element generally consists in part of a valve member which is actuated by a temperature sensing device. This valve member regulates the flow of a medium, either a liquid or a gas, be it hot or cold, to the conditioning unit. The temperature sensing elements that are presently available commercially have been developed to the extent that they respond to minute changes in the measured variable such as heat. However, this accuracy of the sensing element cannot be fully appreciated unless the control valve which is actuated by the sensing element is comparably accurate. The valves that have been used heretofore, due to their mechanical nature, have been seriously limited due to hysteresis, friction, and other error inducing forces. Consequently, the accuracy with which an air conditioning system could be controlled was seriously limited by the control valve.

Therefore, it is an object of the invention to provide a control valve that is novel in construction.

Another object of the invention is to provide a control valve in which hysteresis and other error inducing forces are substantially eliminated.

A still further object of the invention is to provide a control valve that is adapted for use in an air conditioning system.

A still further object of the invention is to provide a control valve that is pneumatically operated and may be actuated by a pneumatic signal generating temperature sensitive device.

A still further object of the invention is to provide a control valve that is economical in construction and simple in operation. These objects and others will be apparent upon reading of the specification with reference to the following drawing.

In the drawing:

Figure 1 is a side elevational view in cross section of the control valve embodying the invention.

Referring now to the drawing, there is shown a control valve provided with an upper casing member 10 and a The diaphragm member 19 is secured in place by the annular bead 21 at its base which is received within the annular groove 22 in the upper casing member 10.

The diaphragm member 19 is molded into the shape of a conical frustum having a ribbed like convolution 24 at I its base to prevent binding of the diaphragm as it is discomplementary lower casing member 11. The two casing members 10 and 11 are secured together by the complementary flanges 13 and 14 and the usual nut and bolt arrangement 15. In their assembled position the casing members 10 and 11 form a chamber generally denoted by the numeral 16. This chamber is divided into an upper compartment 17 and a lower compartment 18 by the diaphragm member 19. I

As will be seen later on, the diaphragm member 19is generally under pressure other'than atmospheric, in the upper compartment 17, provided by a suitable temperature sensing element which communicates thereto through the fixture 20. The lower compartment, however, is at atmospheric pressure due to the cutaway portions 23 in the casing member 11.

placed either upwardly or downwardly. Although this is the preferred embodimentof the diaphragm, it is contemplated that other types and shapes of diaphragms may be used in the practice of the invention. Underlying the diaphragm 19 is a diaphragm support member 25 which receives and centrally positions the cup member 26 by the annular shoulder 27. The cup member 26 has a conical shaped chamber 29 which receives the bushing 28 provided with a spherical surface 30. The spherical surface 30 compensates for any misalignment between the diaphragm support member 25 and the valve stem, as will be explained more fully later on.

The bushing 28 has an internally threaded bore 31 which engages the threaded portion 33 near the upper end 32 of the valve stem 34. When the valve is in normal repose, the spherical surface 30 is seated within the conical surface 29 so that the end 32 is spaced from the support member 25.

The lower casing 11 is provided with the bore 35 which receives the guide member 36. The guide member 36 at its upper end is provided with the threaded portion 37 which receives the locknut 38 for holding the guide member 36 in place. A second locknut 39 is received on the threaded portion 37 and co-operates with the cup member 26 to confine the coil spring 40 therebetween, as shown in the drawing. It can be seen that the load on the coil spring can be adjusted by simply varying the height of the locknut 39 on the threaded portion 37.

A second guide member 44 is press fitted into the bore 36a so that the two guide members co-operate to prevent any misalignment of the stem 34. Although the two guide members 36 and 44 are precision fitted to the stem 34, it is possible that there will be some leakage from the fitting 48 along the stem 34. In order to prevent the controlled media from leaking into the lower compartment 18, the central portion of the stem is enclosed by the bellows 41. The bellows 41 is held in place as shown in the drawing by the bushing 42 which is threadably received within the bore 43 of the guide member 36. When the bushing 42 is tightened in its holding position, it abuts the stepped washer 41a which is secured to the lower end of the bellows 41, so as to hold the latter into sealing engagement with the guide member 44. It may also be desirable to provide a means for further reducing any leakage along the stem such as the spring and cup assembly, generally denoted by the numeral 46, as shown in the drawing. The cup member 46a provides a vertical support for the guide member 44 and serves to confine any leakage along the valve stem. The spring 46b holds the resilient washer 460 so as to provide a check valve arrangement. In this manner any fluid in the bellows 41 may be forced past the washer 46c against the force of the spring 46b when the bellows is compressed. On the other hand, fluid attempting to move in the other direction past the cup assembly will tend to increase the sealing engagement of the washer 46c.

The fitting 48 is incorporated into the conduit through which the measured variable such as steam, water, or air flows. A valve member, generally denoted by the numeral 49, co-operates with the fitting 48 to control the flow of the measured variable therethrough as actuated by the previously described diaphragm assembly. As shown in the drawing, the valve 49 is secured to the stem 34 by the flexible connector 49a which will compensate for any misalignment between the stem and the valve seat.

The flexible ring 50 of the valve 49 is adapted to seat on the surface 51, as shown in the drawing. The flexible ring 50 may be formed of any suitable material such as rubber or plastics that will generally conform to the surface 51 and provide an impervious sealing engagement Extending below the flexible ring 50 is the tapered plug 52 which co-operates with the hole 53 to meter the flow of the measured variable therethrough.

The operation of the control valve will now be briefly described. If the temperature sensing element should send an increased pressure signal to the chamber 17, the diaphragm 19 and the underlying support member 25 will be forced downwardly so as to displace the cup member 26 which is seated against the support member 25 and is held there by the force of the spring 40. If the spring should have an uneven bias due to the ends not being parallel, the spherical surface 30 will permit adjustment of the support member with respect to the stem 34. Thus, even though the support member 25 is canted with respect to the stem 34 due to the exertion of an uneven force by the spring 40, there will still be an evenly distributed force exerted on the stem 34. This arrangement permits the use of two guide members which prevent any lateral play of the stem 34 without any tendency for the stem 34 to bind with the guide members. As the diaphragm support member 25 continues downwardly, the cup member 26 is forced out of engagement with the spherical surface 30 until the end 32 abuts the under side of the support member 25. During this part of the operation, the stem 34 has not been moved from its previous position. However, as the support member 25 moves further downwardly, the stem is likewise moved downwardly until the pressure in the compartment 17 is equal with the force exerted by the spring 40 or until the valve 49 is in its seated position.

Now, if the temperature sensing element should send a decreased pressure signal to the valve, the diaphragm 19 and the support member 25 will move upwardly. At this point the end 32 will become spaced from the support member 25 and the spherical surface 30 will once again become seated on the conical surface 29, as shown in the drawing. The entire valve assembly will continue upwardly until the force of the spring 40 is in equilibrium with the pressure in the compartment 17.

The previously described arrangement for connecting the stem 34 to support member 25 compensates for any tendency of the spring 40 to exertan unevenly distributed force on the support member 25 due to the spring ends not being parallel. In this manner the use of a twopoint guide system for the valve stem is permitted. Thus any hysteresis that would ordinarily be present in such a valve is substantially eliminated because the stem 34 cannot bind with any other of the associated parts, such as the guide members.

Furthermore, the use of the two-point guide system permits the use of precision and close tolerances in the construction of the valve and will tend to eliminate any error inducing forces such as friction. It should be noted that the flexible surface 50 co-operates with the two-point guide system and the spherical joint connection to eliminate the noise inherently present in the ordinary type valve, as well as insuring seating engagement. It can now be seen that the valve herein described substantially eliminates sources of error such as hysteresis which are present in ordinary control valves and at the same time provides noiseless and smooth operation.

Though certain elements and uses have been specified in the description of the invention, it is to be understood that these are merely by way of example and are not to be construed as limitations. It is contemplated that the valve may be modified within the scope of the claims without departing from the spirit of the invention.

I claim:

1. In a control valve comprising a flexible diaphragm, a support member underlying and in touching relationship with said diaphragm, a frustoconical member having an aperture therein underlying said support member, a stem one end of which extends through said aperture and into said frustoconical member, a spherical bushing secured adjacent said end to said stem and seated on said frustoconical member, the said end of said stem being normally spaced from said support member when said bushing is seated against said frustoconical member, means yieldingly biasing said frustoconical member into engagement with said bushing, and a valve member flexibly secured to the other end of said stem and adapted to be actuated by said diaphragm.

2. In a control valve comprising a flexible diaphragm, a support member underlying and in touching relationship with said diaphragm, a frustoconical member having an aperture therein underlying said support member, a stem one end of which extends through said aperture and into said frustoconical member, a spherical bushing secured adjacent said end to said stem and seated on said frustoconical member, the said end of said stem being normally spaced from said support member when said bushing is seated against said frustoconical member, means yieldingly biasing said frustoconical member into engagement with said bushing, a valve member flexibly secured to the other end of said stem and adapted to be actuated by said diaphragm, a first guide means for said stem, and a coaxially spaced second guide means for said stem.

3. A control valve comprising a flexible diaphragm, a support member underlying and in touching relationship with sard diaphragm, a frustoconical member having an aperture therein underlying said support member, a stem one end of which extends through said aperture and into said frustoconical member, the said end of said stern being normally spaced from said support member, a spherical bushing secured adjacent said end to said stem .and seated on said frustoconical member, a spring member abutting said frustoconical member and biasing said frustoconical member into engagement with said spherical bushing, a valve member flexibly secured to the other end of said stern and adapted to be actuated by said diaphragm, a first guide means for said stem, and a second guide means for said stern coaxially spaced from said first guide means.

4. A control valve comprising a diaphragm operated by pneumatic pressure signals, said diaphragm mounted on a support member, a frustoconical cup member underlying said support member and in touching relationship therewith, said frustoconical member having an aperture therein, a stem one end of which extends through said aperture into said frustoconical cup member, a spherical bushing secured to said end, a spring member biasing said aforesaid conical cup member into engagement with said spherical bushing whereby said end is normally spaced from said support member, a valve member flexibly secured to the other end of said stem, flexible sealing means on said valve member, and first and a coaxially spaced second guide means for said stem.

5. In a control valve having a flexible diaphragm adapted to be actuated by variations in pressure, and a valve member spaced from said flexible diaphragm and movable in response to the movement of the same, the combination comprising a support member underlying and in touching relationship with the flexible diaphragm, a cupshaped member having an aperture therein in abutting relationship with said support member to form a chamber, a stem member extending through said aperture at one end into said chamber and secured at the other end to the valve member, and a bushing embracing said stem member adjacent the said one end thereof, said bushing having a spherical surface in which said spherical surface normally being seated on said cup member, said one end of said stem being spaced from said support member when said bushing is in its seated position, said stem being axially movable with respect to said support member whereby said bushing is unseated when said support member moves in the direction of the valve member.

6. In a control valve having a flexible diaphragm adapted to be actuated by variations in pressure, and a valve member spaced from said flexible diaphragm and movable in response to the movement of the same, the combination comprising a support member underlying and in touching relationship with the flexible diaphragm, a cupshaped member having an aperture therein in abutting relationship with said support member to form a chamber, a stem member extending through said aperture at one end into said chamber and secured at the other end to the valve member, a bushing embracing said stem member adjacent the said one end thereof, said bushing having a spherical surface in which said spherical surface normally being seated on said cup member, said one end of said stem being spaced from said support member when said bushing is in its seated position, said stem being axially movable with respect to said support member whereby said bushing is unseated when said support member moves in the direction of the valve member, and a spring resisting movements of said diaphragm and biasing said cup member toward seated position against said bushing.

7 In a control valve having a flexible diaphragm adapted to be actuated by variations in pressure, and a valve member spaced from said flexible diaphragm and movable in response to the movement of the same, the combination comprising a support member underlying and in touching relationship with the flexible diaphragm, a frustoconical cup member having an aperture therein in abutting relationship with said support member to form a chamber, a stem member extending through said aperture at one end into said chamber and secured at the other end to the valve member, a spherical member embracing said stem adjacent said one end within said chamber and normally seating on said cup member,

said spherical member providing for rotation of said stem with respect to said support member, said stem being axially movable with respect to said support member whereby said bushing is unseated when said support member moves in the direction of the valve member so that said one end of said stem abuts said support member, and a spring resisting movements of said diaphragm toward the valve member and biasing said cup member toward seated position against said spherical member.

8. In a control valve having a flexible diaphragm adapted to be actuated by variations in pressure, the combination comprising a support member underlying and in touching relationship with the flexible diaphragm, a frusto-conical cup member having an aperture therein in abutting relationship with said support member to form a chamber, a stem member extending through said aperture at one end into said chamber, a valve member flexibly secured to said stem spaced from said cup member, a spherical member embracing said stem adjacent said one end within said chamber and normally seating on said cup member, said spherical member providing for rotation of said stem with respect to said support member, said stem being axially movable with respect to said support member whereby said bushing is unseated when said support member moves in the direction of the valve member so that said one end of said stem abuts said support member, and a spring resisting movements of said diaphragm toward said valve member and biasing said cup member toward seated position against said bushing.

References Cited in the file of this patent UNITED STATES PATENTS 2,311,110 Johnson Feb. 16, 1943 2,456,403 Goehring Dec. 14, 1948 2,496,215 Jones Jan. 31, 1950

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