US2883998A - Vacuum control valve - Google Patents

Description

A. E. B'ROUGHTON VACUUM CONTROL VALVE April 28, 1959 Filed Jan. 14, 1954 /nventor flrbhur- .E. Brag/16021,

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an upper section 11. peripheral marginal portion securely clamped between United States Patent C) 2,883,998 VACUUM CONTROL VALVE Arthur E. Broughton, Glens Falls, N.Y., assignor to Frances I. Broughton, Glens Falls, and Douglas H. Newcomb, Hudson Falls, N.Y., as trustees Application January 14, 1954, Serial No. 404,080

1 Claim. (Cl. 137116.3)

This invention relates to a diaphragm type control valve and particularly to a vacuum control Valve for suction heads on paper making machines.

: This application is a continuation in part of my copending application, filed December 18, 1948, Serial No. 66,007, and entitled Vacuum Control, now abandoned.

Chattering in vacuum control valves has long been a serious problem and causes undue wear and damage to the parts thereof in addition to causing fluctuation in the suction produced on the vacuum head. I have found also that a diaphragm actuated vacuum control valve is considerably more sensitive and efficient as well as being more durable and requiring less maintenance than do the piston actuated valves disclosed and claimed in my prior patents, No. 1,962,477 granted June 12, 1934, and No. 2,147,877 granted February 21, 1939.

' i It is an object of my present invention to provide a vacuum control valve particularly adapted to substantially eliminate chattering while maintaining a substantially constant vacuum on a suction head.

It is another object to provide a diaphragm actuated control valve for suction heads for maintaining a substantially uniform suction in said head without being rendered inoperative by the effect of the corrosive vapors from the 'paper making solutions of a paper making machine.

More specifically, it is an object to provide a control valve for maintaining a substantially uniform vacuum in a suction head whereby, if the suction in the head falls below a predetermined limit, additional suction will be supplied thereto and, if the suction rises above a prede- "termined limit, the same will be released, said control valve including a relief valve constructed to provide an opening of gradually increasing area to prevent sudden pressure changes within the suction head and thus prevent chattering of the valve.

These and other objects and advantages of this invention will more fully appear from the following descrip tion made in connection with the accompanying drawings wherein like reference characters refer to the same or similar parts throughout the several views, and in which:

Fig. 1 is a central vertical sectional view taken through my new vacuum controller showing the control valve in open position and the relief valve in closed position;

Fig. 2 is a fragmentary central vertical sectional view showing both the control valve and relief valve in closed position;

Fig. 3 is a view similar to Fig. 2 showing the relief valve in partially open position;

Fig. 4 is an enlarged fragmentary central vertical sectional view of the relief valve in closed position; and

Fig. 5 is a diagrammatic elevational view showing my vacuum control valve connected in a vacuum system.

As illustrated in the accompanying drawings, I pro-,

vide a controller having a lower casing section and A diaphragm 12 has the outer said two sections 10 and 11 as by the cap screws 13.

"A double conical poppet valve structure, designated as an entirety by the letter A, is operatively connected with 2,883,998 Patented Apr. 28, 1959 "ice the diaphragm 12 to be actuated thereby. The valve A has a casing 14 with a pair of openings 15 and 16, the opening 15 being connected with a source of suction supply such as the vacuum pump 17 driven by an electric motor 18 as illustrated in Fig. 5. The valve opening 16 is connected with a controlled vacuum line ,19 extending to a vacuum head 20, such as the flat box for a paper making machine.

The lower casing section 10 defines a control chamber 21 therewithin and has a communication opening 21a to which a sensing communication conduit 22 is connected at one end, the other end thereof being connected with the controlled vacuum line 19 extending to the vacuum head 20 and equalizing the pressure between said conduit 19 and said chamber 21. The diaphragm 12 is resiliently urged upwardly by a control spring 23 as best shown in Fig. 1. A spring seat member 24 is securely fixed to the underside of diaphragm 12 and receives the upper end of spring 23 in seated relation against the outer peripheral portion thereof. The upper surface of said outer marginal portion is curved downwardly in divergent relation to the diaphragm 12, as indicated at 25, to facilitate flexing of the diaphragm 12 without undue wear on the portion thereof adjacent said seat member 24. The lower end of control spring 23 is mounted on an adjustable seat 26, as best shown in Fig. 1, and a screw shaft 27 is journalled in said adjustable seat member 26 and is threadably mounted through the bottom of lower casing section 10 through insert plug member 100. Suitable means for turning the screw shaft 27 within threaded insert 10a are provided, such as a gripping handle 28 best shown in Fig. 1. Obviously, turning shaft 27 in insert 10a projects the lower spring seat 26 upwardly or retracts the same downwardly, and thereby adjusts the compression of spring 23 and the force exerted thereby on diaphragm 12.

An opening is provided in the central portion of diaphragm 12, and a relief valve B is mounted therein to control the flow of air under atmospheric pressure therethrough into control chamber 21. The valve B has an annular seat member 29 securely fixed to the diaphragm 12 as by being attached to the spring seat 24 by suitable means such as the screws 30, the valve seat 24 and spring seat 29 forming backing members for each other. A valve sleeve 31 extends through the central opening in valve seat 29 and the openings in diaphragm 12 and spring seat 24 and has a sealing flange 32 formed on the upper portion thereof with a sealing gasket 33 interposed between the flange and the valve seat 29. The upper portion of valve sleeve 31 is secured to an actuating stem 34 to which a pair of frusto-conical control valve elements 35 are fixed. Said elements 35 control the flow through valve casing 14 and are respectively provided with a pair of valve seats 36 into which said elements are received when in closed position, as shown in Figs. 2 and 3. The valve sleeve 31 is hollow below the connection with stem 34 and a relief opening 31a of sufiiciently small diameter to materially restrict the flow of air therethrough is provided in the upper portion of sleeve 31 adjacent seat 29 when said valve is closed so that slight opening of the valve will produce a restricted area of communication between the atmosphere and control chamber 21. This prevents the sudden increase of pressure within said chamber 21 as said valve is initially opened, which would obviously, produce a rapid snapping shut of the valve and ultimately produce chattering until the overall pressure became adjusted. Additional apertures 31b are'provided in downwardly spaced relation from aperture 31a to provide increased areas of communication as the valve B is progressively opened by excessive vacuum in chamber 21 pulling diaphragm 12 downwardly away from flange 32 after the valve elements 35 have been closed, as shown making solutions.

in Fig. 3. A relief spring 37 has its upper end seated against the central portion of valve seat member 24 surrounding the opening thcrethrough and extends downwardly therefrom in surrounding relation to valve sleeve 31 and is seated at its lower end against a spring seat collar 38 fixed to the lower portion of sleeve 31. This spring 37 urges the valve flange 32 downwardly into engagement with seat 29 and also, of course, urges valve elements 35 downwardly into closed seated position whenever the diaphragm 12 is pulled downwardly by excessive vacuum in chamber 21. The valve seat member 29 has a smoothly contoured outer periphery 2% for engagement with the adjacent portion of diaphragm 12 when the same is flexed.

The following is a description of the operation of my vacuum control valve as disclosed herein. The vacuum pump 17 provides a source of vacuum for suction head 20, and the valve A controls communication between said pump 17 and said head. Since the chamber in the suction head 20 and the control chamber 21 are in communication through pressure sensing conduit 22, the pressures therein are substantially equal. Whenever the suction in head 20' and chamber 21 fall below a predetermined limit, the adjusta-bly compressed control spring 23 will overcome the downward pulling force of the suction in chamber 21 on diaphragm 13 and urges said diaphragm upwardly whereby the valve flange 32 and valve stem 33 connected therewith will carry the valve elements into gradually opening position. However, when the suction in chamber 21 is suflicient to overcome the upwardly directed force exerted by spring 23 on diaphragm 12, the diaphragm will be flexed downwardly to seat valve elements 35 in closed position and, if the suction is still sufficient to draw diaphragm 12 downwardly against the force of springs 23 and 37, the relief valve B will be gradually opened and air under atmospheric pressure will be introduced through the restricted opening 31a as the same is exposed to the atmosphere by initial opening of valve B. Obviously, additional opening of valve sleeve 31 progressively increases the area of communication between the atmospheric air pressure and control chamber 21 in order to increase drastically reduced pressures in said chamber, if necessary, and overcome excessive vacuum in suction head 20. This prevents a sudden rush of air into chamber 20 when valve B is initially opened to cause valve B to be again quickly closed and open valve A, which, of course, produces the undesirable chatter of the valve previously referred to herein. The chatter of the valve is caused by a sudden change in the pressure within chamber 21, and it will 'be seen that my present relief valve structure is designed to prevent any such rapid change. The tapered control valve structure prevents a high suction from being suddenly imposed upon the suction head 20 since the tapered construction thereof prevents large open areas of communication from vbeing suddenly created between the vacuum source and the vacuum head.

It is obvious that my present controller construction, as disclosed herein and as previously disclosed in my copending application, of which the instant application is a continuation and part, entirely eliminates the deleterious effect produced by the corrosive vapors from the paper By replacing the pressure responsive control piston with the control diaphragm 12, metal to metal contact of this important controller element is entirely eliminated and thus it is obvious that any corrosion which might occur on the inside surface of lower casing would have no harmful eflect whatever on the sensitivity or controlling operation of the diaphragm member. With the substantial elimination of chattering by my present relief valve structure, it will be seen that I have provided an extremely durable, long lasting and highly accurate control valve which is easily and quickly adjustable and which will require an absolute minimum of maintenance.

It will, of course, be understood that various changes may be made in the form, details, arrangement and proportions of the parts without departing from the scope of this invention which, generally stated, consists in the matter shown and described herein and set forth in the appended claim.

What I claim is:

A device for automatically controlling, and maintaining substantially constant, the vacuum pressure in a vacuum head, said device comprising a casing formed from three separate units and means securing said units together in superposed relation to form a unitary structure having three separate chambers therein; a flexible diaphragm having a central opening therein being interposed between said bottom unit and the intermediate unit and separating the chambers laterally enclosed by said units; a valve seat on the upper side of said diaphragm; a first spring seat on the under side of said diaphragm; means securing said seats together around the opening in said diaphragm; a second spring seat within said bottom unit below said first seat; a comparatively heavy helical spring compressed between said spring seats; means for adjusting the compression of said spring from apoint relatively remote from said device and comprising a threaded rod extending through a threaded opening in the bottom of said bottom unit; and cooperating with said second spring seat to raise and lower the same;the top unit having a control valve therein including astern extending downwardly through said intermediate unit and through said diaphragm into the lower unit with the lower end thereof disposed in spaced relation below said diaphragm and provided with a third spring seat at said lower end, a fourth spring seat immediately surrounding the portion of the valve stem extending downwardly-below the diaphragm and concentrically disposed within said first spring seat adjacent the lower surface of the diaphragm and said stem normally holding said control valve in open position, a normally closed valve cooperating with the valve seat on the top of said diaphragm, and a comparatively weak helical spring surrounding said valve stem and compressed between the third and fourth spring seats and normally holding said last mentioned valve in seated position; said top unit being provided with an air inlet, for connecting a -pipe thereto communicating with said vacuum head, and with an air outlet for connecting a pipe thereto communicating with a source of vacuum; said intermediate unit being provided with an opening therein to aiford communication with the atmosphere; and said bottom unit being provided with an opening therein for connecting a pipe thereto communicating with said vacuum head; whereby, the normal pressure in said bottom unit will .besubstantially the same as in said vacuum head, and a reduction in said pressure, beyond a point determined by the adjustment of said compression spring in said bottom unit will eflect a downward flexure of said diaphragm by,;atmospheric pressure on the upper side thereof, close said control valve and pull the valve seat on said diaphragm away from the valve cooperating therewith to effect opening thereof and admit air to said vacuum :head through said bottom unit, and thus raise the pressure therein.

References Cited in the file of thispatent UNITED STATES PATENTS 1,501,331 Guliek July 15, 1924 1,962,477 Broughton June 12', 1934 2,147,877 Broughton Feb. 21, 1939 2,252,152 Work Aug. 12,1941 2,305,519 Dunmire Dec. 15, 1942 2,556,308 Weather-head June 12, 1951 2,731,026 Hughes Jan. 17, 1956 2,745,322 Broughton May 15, 19.56

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