US3766933A

US3766933A - Rolling diaphragm vacuum control

Info

Publication number: US3766933A
Authority: US
Inventors: C Nicholson
Original assignee: Broughton Corp
Current assignee: Broughton Corp
Priority date: 1970-07-27
Filing date: 1970-07-27
Publication date: 1973-10-23
Anticipated expiration: 1990-10-23
Also published as: JPS56137213U

Abstract

A vacuum control device for controlling the vacuum delivered to certain elements of paper making machines including a housing wherein passages are provided to permit selective control from a vacuum header or atmosphere to a flat box of a paper making machine and wherein a flexible member is provided to control communication through the vacuum and atmospheric introduction passages which member is normally held in closing position to said passages through the utilization of the introduced vacuum, but will upon proper sensing of the element to be controlled, be rolled past certain of the passages to either open or close the same to thereby control the admission of vacuum or atmospheric pressure or pressure above atmospheric pressure.

Description

United States Patent 1 1 Nicholson, Jr.

[ Oct. 23, 1973 [63] Continuation-impart of Ser. No. 835,709, June 23,

1969, abandoned.

[52] U.S. Cl..... 137/1163, 137/596.18, 137/DIG. 8, 25l/DIG. 2 [51] Int. Cl. Fl6k 31/365 [58] Field of Search 137/116, 116.3, 596,

137/596.l8, 625.3, 625.33, 625.34, 625.37, 625.66, 625.67, DIG. 8; 25l/61.l, 331, 334, 358, DIG. 2

[56] References Cited UNITED STATES PATENTS 2,950,730 8/1960 Svensson 137/1163 ROLLING DIAPHRAGM VACUUM CONTROL Inventor: Charles B. Nicholson, ,Ir., Glens Falls, NY.

Assignee: Broughton Corporation, Glens Falls,

Filed: July 27, 1970 Appl. No.: 58,283

Related U.S. Application Data 7'0 drnosrmsze' Otto 0251/61.] Macy l37/625.67

Primary Examiner-Robert G. Nilson Att0rneyJames R. Cwayna [57] ABSTRACT A vacuum control device for controlling the vacuum delivered to certain elements of paper making machines including a housing wherein passages are provided to permit selective control from a vacuum header or atmosphere to a flat box of a paper making machine and wherein a flexible member is provided to control communication through the vacuum and atmospheric introduction passages which member is normally held in closing position to said passages through the utilization of the introduced vacuum, but

will upon proper sensing of the element to be controlled, be rolled past certain of the passages to either' open or close the same to thereby control the admission of vacuum or atmospheric pressure or pressure above atmospheric pressure.

9 Claims, 5 Drawing Figures 0190 FIOM REGUt/QTOR WENTEDIIM 23 an 3 93 sum-:1 1 BF 3 0190 FROM RfGUlflTOR am Amrosraszs FRO/7 HEWDER FIG? I N VEN TOR 'WQW lrrmwsy CHARLES B. NlCHOLSON JR.

PAIENIEU "B 2 3 i975 SHEET 2' OF 3 7'0 HEADER INVENTOR CHARLES B. NICHOLSON JR.

flrramwsr & BY r PAIENIEUnmBIm 3,766,933

I SHEET m3 CONTROLLING PRESSURE INPUT ABOVE ATMOS.

PRESS.

VACUUM HEADER TO FLATBOX INVENTOR CHARLES B.NICHOLSON JR.

BY 322-45: 5' W 21% A TJ'JkA/Ey ROLLING DIAPHRAGM VACUUM CONTROL This application is a continuation in part application of an application filed June 23, 1969, Ser. No. 835,709 filed by Charles B. Nicholson, .Ir. entitled Rolling Diaphragm Vacuum Control, now abandoned.

In the past, various vacuum control devices for controlling specific operations of paper making machines have been provided which control mechanisms primarily assume the normally assumed shape of a valve wherein a passage is provided between a vacuum header or source of vacuum and the element to be controlled which passage is surrounded by a seat member with a valving device being placed in shiftable relation to said valving seat such that a normal valving function will be performed. Applicant has through this concept, provided a new and unique valving arrangement wherein the normal valving member and seating arrangement is completely eliminated and rather a rolling flexible member is utilized to selectively and controllably open certain selected passages to control the vacuum supply to for example, a flat box. In addition to this particular concept, a sensing arrangement may be provided wherein the rolling operation is controlled in accordance with a predetermined vacuum pressure to be delivered to the element to be controlled with an automatic movement of the rolling member taking place upon any variations from the set condition for the element.

Applicants device includes variations of the prime concept which will incorporate either a vacuum breaking device such that a vacuum system may be opened to atmosphere upon the system reaching a predetermined vacuum pressure level or that may be utilized to maintain vacuum at a predetermined level by the introduction of either vacuum or atmospheric pressure to the particular sensed area. Primarily, each of the concepts includes the concept of pressure introductions through a selective valving system wherein the valving member provides a flexible member to roll upon itself when opened or closed such that a unique valve member is utilized rather than the now readily available valve and seat structure.

It is therefore an object of applicants invention to provide a vacuum control member incorporating a flexible valving member designed to selectively open or maintain control through communicating passages by being selectively moved thereacross.

It is a further object of applicants invention to pro vide a rolling diaphragm valving member to control vacuum systems wherein the diaphragm is designed to roll upon itself and thereby open and control communication between certain passages in the valving device.

It is still a further object of applicants invention to provide a rolling diaphragm or bellows valving system to control vacuum pressures which includes a sensing arrangement operatively connected to the operative section, which operative section requires control such that pressure will be automatically maintained at this particular operative section either through the introduction of vacuum or atmospheric pressures thereto.

It is still a further object of applicants invention to provide a valving member consisting and including a pair of rolling diaphragm members having a'control chamber therebetween for introduction of pressures thereto which chamber depends for its actuation upon differentiation in areas of the two rolling diaphragm members.

provide a rolling diaphragm valving device including a controlling pressure chamber arranged between a pair of rolling diaphragm members which will provide an automatic actuation device for the introduction of either relief atmospheric pressure, or controlled vacuum pressure into an area in which the pressure is to be controlled.

These and other objects and advantages of the invention will more fully appear from the following description 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 vertical section taken substantially centrally through a valving member which incorporates the concepts of applicants invention and illustrated in connective position between a vacuum header and a flat box of a paper making machine;

FIG. 2 is a transverse section taken substantially along Line 2-'2 of FIG. 1;

FIG. 3 is a vertical section taken substantially centrally longitudinally through a modified form of the invention; and

FIG. 4 is a transverse section taken substantially along Line 4-4 of FIG.3.

FIG. 5 is a vertical section taken substantially centrally longitudinally through a modified form of the invention which basically includes the variations and the improvements over the original invention.

In accordance with the accompanying drawings the utilization of applicants concept to control the vacuum pressure at flat boxes of paper making machines is illustrated in FIGS. 1 and 2 while the utilization of the concept to control or relieve excessive pressure in vacuum headers is illustrated in FIGS. 3 and 4.

In controlling the flat box pressure the unit 10 is positioned between the vacuum header H and flat box Line F and includes a housing body 11 provided with attachment flanges 11a, 11b, with the entire control portion of the unit 10 carried by and in the housing 11. The housing 11 provides a control cavity 12 having a cover plate 13 by which the control cylinder 14 is placed into cavity 12.

Communication between the cavity 12 and the flat box line F is provided through passage 15 in flange 11a. Communication between the cavity 12 and the vacuum header H is provided through the hollow toroidal insert 16 arranged generally centrally in the cavity 12 communicating through passage 17 in flange 11b and the plurality of radially extending passages 18 formed in the inner wall 16a of the toroidal section 16. As illustrated the toroidal section 16 provides inner wall 16a opening in an axial direction to permit insertion of the control cylinder 14.

Control cylinder 14 includes a first hollow, generally arcuate member 20 having a flange 20a on the bottom the closure effect for the closure member 22 to the control cylinder 14.

A vacuum introduction Line 26 is provided between the loading chamber 24 and the header II. This Line 26 permits, through the utilization of a regulator R, loading of the chamber 24 such that predetermined vacuum pressures will be maintained at the flat box.

Cover plate 13 is pressure sealed to the control cylinder 14 in such a manner to permit the assembly of the control cylinder H to the toroidal vacuum section 16 as access must obviously be afforded to attachment screws 21 interiorly of the cavity 12.

Sets of apertures designated 27, 28 are provided respectively above and below the cover plate 14 to permit atmospheric pressures to be selectively to the interior of cavity 12.

Within the control cylinder 14 a floating piston member 30 is provided. Piston 30 includes a connective control end 31 arranged in controlled relation to the loading chamber 24. This connective control end 31 includes the afore-mentioned flexible, resilient, diaphragm bellows member which in its common form would comprise a cup-shaped member having a radially extending flange at its upper end. When related to the drawing the flange is designated 32, the sides of such cup 33 and the bottom 34. The flange 32 is captured between the afore-mentioned flanges 20b, 22b and the bottom 34 is captured through the use of a generally arcuate flat plate member 35 and an inverted cupshaped member 36 on opposite sides of the bottom 34. These two capturing elements are clamped by a connecting rod 37 extending therethrough with capturing elements 37a, 37b cooperatively associated therewith.

The concept of the bellows member is to permit a relatively large stroke of the connective rod 37 by permitting the bellows to roll upon itself. Obviously, to control such rolling the sizing of the upstanding inverted cup-shaped clamp element 36 in relation to the interior wall of the dome shaped closure 22 is important and in this drawing this relationship is distorted to permit full explanation of the coaction of the elements. It should also be obvious that this sensing bellows could be provided as a flat diaphragm member if the same were large enough to permit the desired stroke.

The connective rod 37 extends to the vacuum and atmospheric introduction area of the cavity 12 and at such area a pair of rolling diaphragm bellows members designated respectively as an atmospheric bellows 40 and a vacuum bellows 41 are provided. The flange portions 40a, 41a thereof are clamped between the aforementioned flange 20a and the upper wall 16b of the to.- roidal section 16 while the side wall portions 40b, 41b thereof are held respectively upwardly into sealing relation to the interior surface of control cylinder 14 and downwardly into sealing relation to the interior wall 16a of the toroidal section 16 which upward and downward relation is maintained through the means for clamping the respective bottom 40c, 410 of the members in spaced relation along the connective rod 37.

The connective rod 37 and the means for clamping the bellows members 40, 41 are designed to provide a rolling, opening and closing action over the vacuum introducing apertures '28 such that a balancing or floating motion will occur in accordance with the loading chamber 24 pressure and the pressure in the flat box.

A plurality of clamp means including a first cupshaped member 45, a spacing member 46 and a second cup shaped member 47 are provided on rod 37 between a shoulder 37c and a member device such as the threaded aperture 47a in cup member 47. The diaphragm bellows members 40, 41, are respectively provided between first cup member 45 and spacer 46 and the second cup clamp member 47. Again the cup members control the rolling effect of the diaphragm bellows members to place the sealing side thereof against a solid surface with the low pressure always acting to hold the same against such surface. To further insure the existence of this relative pressure differential a

passage system

48, 49 is utilized to introduce atmospheric pressure into the area 50 defined by the diaphragm. To further expound on this relative pressure concept the vacuum control diaphragm 41 has the relatively low pressure of the header I-I acting to pull the same against wall 16a of the toroidal section 16 and the atmospheric control diaphragm H as the relatively lower pressure within cavity 12 acting to pull the same against the inner wall of control cylinder 14.

In operation of this unit vacuum pressure is introduced into loading chamber 24 to thereby draw the connective control end 31 and rod 37 upwardly thus drawing up or rolling diaphragms 40, 41 upwardly to roll over to close atmospheric apertures 28 and to roll over to open at least certain of the vacuum introducing apertures 18. When the proper vacuum pressure exists at the flat box the regulator acts to maintain this attained pressure in the loading chamber 24.

As the formed sheet of paper passes over the flat box the vacuum pressure in the flat box will vary and as these variations occur the pressure existing in the flat box is transmitted to the cavity 12 and the unit will operate to maintain the predetermined pressure by either introducing more vacuum or by the introduction of atmospheric pressure into the cavity 12. For example, should the pressure in the flat box decrease, i.e. higher vacuum than proper, the control unit will move downwardly to open the cavity to atmosphere while closing or tending to close vacuum communication. As the pressure in cavity 12 and thus the flat box pressure increases to its proper level this motion will reverse to the point where it should be obvious that if the vacuum pressure is less than desirable the control unit will move upwardly to open the passages 18 between the header H and the cavity 12. In this manner then a continuously operating unit is provided which will maintain proper flat box pressure.

In the modification of the device as illustrated in FIGS. 3 and 4, the unit will primarily perform a relieving function which will open the header H to atmospheric pressure should the vacuum in the header H exceed a predetermined limit to prevent what is termed dead ending in which the vacuum pumps are forced to operate against a closed system.

In the form shown, this modified form designated generally 50, includes a generally T-shaped housing having a pair of

opposed attachment flanges

51, 52, and a third attachment flange 53 arranged to attach the unit to the vacuum header H. A screening attachment 54 is provided on flange 51 having a screen 540 therein and a regulator mounting attachment 55 is provided on the opposed flange 52 with a control member 56 mounted thereon controlling the introduction of vacuum to a control portion 57 within the housing. Regulator 56 receives vacuum from a header connecting line 58 and delivers the same through passage 55a into the control portion 57.

. A control cylinder 60 is provided interiorly of the housing 50 having one end 60a thereof sealed to screening flange 54 with the other end provided with a radially extending flange 60b which is sealingly clamped between flange 52 and the regulator attachment plate 55. A plurality of apertures 61 are provided in spaced relation generally longitudinally centrally of the cylinder 60 to be in communicating alignment with the header communicating passage 53a. lnteriorly of control cylinder 60 a movable, flexible, valving diaphragm bellows 65 is provided to selectively open and close the apertures 61 by rolling upon itself as the pressure in the control section 57 varies.

The diaphragm 65 includes on it the first described device an inverted cup shaped unit having a radially extending flange 66 for clamping between flange 52 and regulator mount 55, side members 67 and a closure bottom 68.

Clamp members

69,70 are provided on opposite sides of the closure bottom 68 with a clamping element 71 exerting the clamping force thereon. In the form shown the

clamp member

69,70 are cup shaped and are provided with longitudinally extending

side elements

69a, 70a of a diameter to permit free movement thereof within the interior of control cylinder 60. A biasing member 71 is provided with the control section 57 with one end 710 thereof located against clamp element 69 and the other end 72a thereof arranged about a locating shoulder 55b on regulator mounting plate 55. This member 72 normally biases the diaphragm 65 downwardly against vacuum introduced into control section 57 to close the aperture 61. The diaphragm member 65 provides, as the pressure in chamber 57 varies in combination with spring 72, an opening and closing effect over the aperture 61 by rolling upon the inner wall of the control cylinder 60 and is held there against by the relatively low vacuum pressure existing in the vacuum header H which communicates with all of the area around the control cylinder 60 and thus through the apertures 61.

The sizing of the aperture as applicant has determined is important to prevent tearing of bellows member 65 and also to control the introduction of atmospheric pressure into header H. Utilizing a staggered aperture arrangement will permit a varied vacuum pressure within chamber 57 which may be lower than the header vacuum to lift the bellows member and permit the introduction of atmospheric pressure while always providing that the relatively higher vacuum pressure in the header H will hold the sides of the bellows against the interior of the control cylinder 67.

In operation of the unit for example, if it is desired to maintain the header pressure at inches, a pressure of 10 inches may be introduced into chamber 57 which will in combination with spring member 72, place the unit in the position of FIG. 3.'lncrease to 20.5 inches in the header will result in an increase in chamber 57 and will immediately start lifting of the bellows against the spring 72. Here again the area of the bottom of the bellows 68 and the clamp members becomes important as the sensitivity of the unit will be a function of this area as compared to the respective areas of the aperture 61. As apertures 61 are opened the admission of atmospheric pressure will cause lowering of the header pressure and pressure in chamber 57. Obviously, as the pressure in chamber 57 again returns to its present condition the bellows system will return to close apertures 61. Conversely to these conditions if the header pressure should vary to 19.5 inches the spring 72 will prevent movement of the bellows 57. In this manner then it should be obvious that this modified form of the invention may be termed a vacuum header controller or vacuum header relief mechanism.

The modified form of the invention and the portion of the invention that includes the new subject matter herein is particularly illustrated in FIG. 5.

In the form shown the controller would be mounted on the standpipe for the individual flat box with a connection 81 being made to the vacuum header for the introduction of vacuum to the unit. In the form shown the unit includes a body member 82, having an opening 83, to atmosphere which would normally be covered with a screening device 84, or the like, to prevent particles from flowing therein.

A first cylindrical sleeve member 85, is positioned within the body 82 and defines a pressure regulated chamber 86, between itself and the body member 82. This chamber 85 communicates with the flat box and is at flat box pressure. A plurality of apertures 85a, are formed through sleeve 85 to permit controlled communication between this pressure regulating chamber and the atmospheric pressure which obviously exists internally of the sleeve number 85. This particular sleeve 85 is of a first diameter, and a rolling diaphragm member 87, is arranged therein for vertical movement therewithin to open the apertures 85a and permit communication between the atmospheric pressure and the pressure regulated chamber 86. This particular diaphragm member 87 is, in the form shown, captured between a cup member 88, and a plate member 89.

Additional chambers are formed below this atmospheric entrance 84, and in the form shown a first cylindrical sleeve member 90 is positioned within the body member 82, and a second cylindrical sleeve member 91 is spaced radially inwardly therefrom, and said second sleeve has a plurality of apertures 91a therein to permit communication between the chamber 92 formed therebetween, which chamber, as illustrated FIG. 5, communicates with the vacuum header such that vacuum header pressure may be introducted through apertures 91a into the area which is directly connected to the flat box.

In order to control communication between the'vacuum header chamber 92, and the flat box area which is designated as 93, a second rolling diaphragm member 94 is provided, again held by a cup member 95, and a plate member 96 on opposite sidles thereof. The two

diaphragm members

87, 94, are connected in sealed relationship through a control shaft 97, such that they will move in unison vertically within the body member 82. It should be noted that the diameter of the aforementioned cylindrical member 91 is less than the diameter of the upper atmospheric cylinder 85 for purposes which will be explained hereinafter.

As stated, the upper chamber 86 is a continuous chamber and is at the same pressure as the flat box area 93. This is obviously accomplished through communicating passages through the high pressure introduction member'98 located intermediate the afore-mentioned

cylindrical members

85, 90 and 91. This atmospheric introduction member basically provides an isolation arrangement and a mounting means for attachment of the rolling

diaphragms

87, 94, thereto such that a cavity 99 is provided therebetween with an inlet passage 99a, affording the means for introducing pressure above atmospheric pressure into the chamber 99.

Basically, the concept of this device is to provide a means for controlling the pressure in the flat box by the introduction of vacuum pressure into the flat box area, or the introduction of atmospheric pressure into the flat box area. Obviously, this is obtained through the upward or downward movement of the combined structure consisting of the upper diaphragm 87, and the lower diaphragm 94 as joined by shaft 97. When the movement of this structure is downward, the apertures 91a will be covered to prevent vacuum introduction into the flat box area and the apertures 85a will be open to permit the introduction of atmospheric pressure to the flat box area. Upon vertical rising of the control element the reverse will occur and higher vacuums will be introduced into the flat box area while the introduction of atmospheric pressure is controlled to sealing of the apertures 85a.

The manner in which this control is obtained is the differentiation in areas between the two diaphragm members. The introduction of pressures above atmosphere into the cavity 99 through the inlet 99a will result in a normal upward movement of the control structure thereby introducing or permitting the introduction of higher vacuums into the flat box area. Obviously, this above atmospheric controlling pressure must also overcome the weight of the combined control structure before such vertical movement will result. Once this weight is overcome, however, the unit will perform its own control function without further adjustment.

In operation of the unit an initial control pressure will be introduced into the cavity 99, and this control pressure will be determined by the amount of vacuum which is desired to be held on the flatbox. The differentials in various sizes when introducing the pressure above atmospheric into the control chamber 99 will result in a net upward vertical movement of the structure opening the communication apertures 91a to vacuum header pressure until the vacuum header pressure and the resultant flatbox pressure is enough to draw the control unit downwardly to cover the apertures 91a. Should the vacuum exceed a desired limit the net effect will be to draw the control structure of the

diaphragms

87,94 downwardly to uncover the atmospheric apertures 85a and permit the introduction of atmospheric pressure into the regulated area. This opening will decrease the vacuum pressures and will cause the control element and associated

diaphragms

87, 94 to rise, thereby cutting off the atmospheric introduction. Obviously, this entire system could not be utilized unless the diaphragms were of different areas.

From the comparison of the two units it should be obvious that in the first form of the invention as particularly illustrated in FIGS. 1 and 2 atmospheric pressure is introduced in the area between the diaphragms, but this does not necessarily serve a control function and the regulator member at the upper portion thereof is necessary for proper control of the unit. With the particular device shown in the improvement of FIG. 5 this additional controlling factor is not necessary and rather the whole unit is controlled by combining the control area into the area between the diaphragms and using only above atmospheric pressure therein.

. It should be obvious that application has provided a unique valving member to control vacuum systems which eliminates common valve seating arrangements by providing a flexible valving member which will selectively seal communicating passages and which will because of the flexibility of the material utilized seal over impurities which may enter the system.

I claim:

1. A pressure controller to define a maintained vacuum pressure to a remote location including:

a. a housing defining a cavity;

b. means permitting connection of said cavity to the remote location;

c. means for introducing vacuum pressure to said cavity including a generally arcuately disposed conduit arranged in said cavity having a connection means for the introduction of vacuum pressure thereto and at least one passage through the inner radial wall thereof for the introduction of such vacuum to said cavity;

d. means for introducing atmospheric pressure to said cavity including a generally arcuately disposed tubular member having the inner wall generally aligned with the inner wall of said vacuum introduction means to provide therewith a common valving surface with means for introducing atmospheric pressure to the interior of said member and having at least one passage through said wall for the introduction of atmospheric pressure to said cavity;

e. shiftable valving means arranged in controlling arrangement to said vacuum and atmospheric pressure introduction means;

f. a control chamber having a movable portion having a controlling connection to said valving means and communicating with said cavity; and

g. means for introducing control pressure to said control chamber whereby said shiftable valving means will be moved in response to pressure existing in said cavity and said control chamber.

2. The structure set forth in claim 1 and a plurality of passages through the wall of said tubular member.

3. The structure set forth in claim 1 and said shiftable valving means including:

a. a flexible diaphragm member arranged to seal against the inner walls of said tubular member and said conduit member and being shiftable therealong by said movable portion of said control chamber whereby the vacuum and atmospheric passages therethrough are respectively opened and closed.

4. The structure set forth in claim 3 and passage means permitting communication of pressure within said cavity against said valving means.

5. The structure-set forth in claim 4 and said valving means including:

a. a pair of flexible diaphragm means extending respectively in both directions from a common location intermediate the vacuum and atmospheric pressure introduction passages on the inner wall of said tubular member and conduit member;

b. connecting shaft means extending from said movable portion of said control chamber to said diaphragm means; and

c. the inner portions of said diaphragm means being attached to said shaft means at spaced locations therealong.

rolling upon themselves.

8. The structure set forth in claim 1 and said tubular member extending exteriorally of said housing with said atmospheric pressure introduction means including a passage through the wall portion thereof exteriorally of said housing.

9. The structure set forth in claim 8 and said control chamber arranged on said tubular member to position said movable portion thereof in operative alignment with said valving means.

Claims

1. A pressure controller to define a maintained vacuum pressure to a remote location including: a. a housing defining a cavity; b. means permitting connection of said cavity to the remote location; c. means for introducing vacuum pressure to said cavity including a generally arcuately disposed conduit arranged in said cavity having a connection means for the introduction of vacuum pressure thereto and at least one passage through the inner radial wall thereof for the introduction of such vacuum to said cavity; d. means for introducing atmospheric pressure to said cavity including a generally arcuately disposed tubular member having the inner wall generally aligned with the inner wall of said vacuum introduction means to provide therewith a common valving surface with means for introducing atmospheric pressure to the interior of said member and having at least one passage through said wall for the introduction of atmospheric pressure to said cavity; e. shiftable valving means arranged in controlling arrangement to said vacuum and atmospheric pressure introduction means; f. a control chamber having a movable portion having a controlling connection to said valving means and communicating with said cavity; and g. means for introducing control pressure to said control chamber whereby said shiftable valving means will be moved in response to pressure existing in said cavity and said control chamber.

3. The structure set forth in claim 1 and said shiftable valving means including: a. a flexible diaphragm member arranged to seal against the inner walls of said tubular member and said conduit member and being shiftable therealong by said movable portion of said control chamber whereby the vacuum and atmospheric passages therethrough are respectively opened and closed.

5. The structure set forth in claim 4 and said valving means including: a. a pair of flexible diaphragm means extending respectively in both directions from a common location intermediate the vacuum and atmospheric pressure introduction passages on the inner wall of said tubular member and conduit member; b. connecting shaft means extending from said movable portion of said control chamber to said diaphragm means; and c. the inner portions of said diaphragm means being attached to said shaft means at spaced locations therealong.

6. The structure set forth in claim 5 and the movable portion of said control chamber including a resilient diaphragm member.

7. The structure set forth in claim 5 and said pair of flexible diaphragm means including: a. cup shaped members having the sides thereof arranged and constructed to sealingly engage said inner walls; and b. strengthening means on the spaced bottom portions thereof to prevent collapsing thereof from said walls and to hold the same thereagainst for rolling upon themselves.