GB2139325A - Pressure regulator - Google Patents

Abstract

A flow control device includes a separator whose movement controls flow through a side port. In one arrangement a pressure regulator includes a diaphragm 12 which moves in response to pressure difference between first and second compartments 14, 16 to control flow through side port 27, compartment 14 being connected to a source 22 of predetermined pressure, and compartment 16 with a high pressure or atmosphere via passage 31 and with low pressure or vacuum through port 27. In other arrangements two (Figs. 3, 5) or three (Fig. 6) diaphragms are provided. A calibrated weight (96, Fig. 5) on the secondary diaphragm (94) biases it toward one of the compartments, depending on the orientation of the regulator. In a further arrangement (Fig. 4) the diaphragm is replaced by a pivoted, stiff plate (83) having a contoured free edge (86) which controls flow through side port (81). <IMAGE>

Description

SPECIFICATION Pressure regulator A pressure regulator that works only under negative pressure and is especially for use in a vacuum line includes an enclosure having an axis and having a side wall approximately parallel to the axis. The enclosure is spanned by a separator affording a first compartment and a second compartment. The first compartment is subject to a predetermined pressure.

The second compartment has a fluid inlet and has a fluid outlet passage. The fluid outlet is located in the side wall and is more or less obstructed by a portion of the separator that moves back and forth and so covers and uncovers the outlet passage. The remainder of the separator moves in a substantially axial direction and in response to pressure differences between the compartments.

The following patents were found in a preliminary novelty search: 3,083,943 Stewart, Jr. et al 3,415,275 Berggren 3,749,353 Pauliukonis 3,762,681 McKinney et al 3,837,615 Espeel 3,918,677 Cowan 3,948,285 Flynn 3,978,878 Rudolph 4,182,371 Moore 4,232,851 Johnson 4,244,554 DiMauro et al FIGURE 1 is a diagrammatic cross-section showing one form of the pressure regulator pursuant to the invention.

FIGURE 2 is a view of a modified form of pressure regulator pursuant to the invention.

FIGURE 3 is a cross-sectional view of a further modified form of the pressure regulator of the invention.

FIGURE 4 is a cross-sectional view of a different modification of the pressure regulator of the invention.

FIGURE 5 is a cross-sectional view of a still further modification of the invention.

FIGURE 6 is a cross-sectional view of a modified form of a device of the invention.

FIGURE 7 is a graph showing some of the performance characteristics of one version of the pressure regulator of the invention.

FIGURE 8 is a plan of a modified form of the pressure regulator of the sort shown in FIGURE 1.

In an exemplary form of the device, as shown particularly in FIGURE 1, there is provided an enclosure 6 extending along and symmetrical with an axis and preferably made up of an upper cup 7 and a lower cup 8 having meeting portions 9 and 11 urged or fastened together in any customary way.

Spanning the enclosure 6 is a separator 1 2 disposed between the upper cup 7 and the lower cup 8 so as to divide the enclosure into a first compartment 14 and a second compartment 16. The first compartment 14 has a passage 21 going to a source 22 of a predetermined pressure. This pressure is preferably at the desired level for regulation and can have any suitable or standard value. The second compartment 1 6 has a passage 23 extending to the volume in which the pressure is to be regulated. The second compartment 1 6 also is open to a passage generally designated 24 and extending in a compartment boundary wall 26 to a vacuum source (not shown).The wall 26, while conveniently circular-cylindrical, preferably has a small substantially planar, possibly chordal or flat portion substantially parallel to or inclined to the axis 21. The passage 24, which may be circular, rectangular or otherwise characterized in cross section, has an inner port or passage 27 open through the axially extending, limited chordal or planar wall 26 to the second compartment 1 6. The important point is that the force resisting opening of the vacuum port is not significantly asserted against movement of the separator.

A port 31, having a valve 32 or a pre-set restricted orifice therein, communicates with the second compartment 1 6 and also with the atmosphere.

As an example, the separator 1 2 as used under the usual practical conditions herein is a generally inelastic, flexible or foldable, pliant, gas impervious sheet. Silicone rubber has been found to be a useful material for the separator. On opposite sides the sheet 1 2 is faced with relatively stiff plates 33 and 34 smaller in area than the separator and appropriately held in position. Alternatively, the plates may be omitted and the sheet 1 2 centrally thickened or otherwise made stiff..

The plates preclude flexure of the separator 1 2 except in some or all of the marginal, peripheral or edge portion thereof. The unreinforced periphery of the separator that is located opposite the port 27 (i.e. the left-hand peripheral portion as shown in FIGURE I) is radially short enough and is so mounted that such portion of the separate periphery flexes to allow for a hinge-like or swinging movement of the separator within the enclosure 6.

The so-constrained separator motion, though largely arcuate, has in general a motion in a direction with a large axial component.

The separator 12, as shown in FIGURE 1, in the right-hand marginal portion is sufficiently flexible to move and fold. This folded local portion of the separator movement has components normal and parallel to the axis 21. This right-hand marginal portion of the separator is approximately U-shaped in crosssection in an axial plane and includes two approximately parallel leg portions of a pair of facing walls extending to a limited circumferential extent and merging gradually with the approximately flat, left-hand portion of the separator. One of the facing walls affords a vertical portion that lies flat against the flat part of the side wall 26 in a position overlying and blocking the port 27 so that there can be no flow there through.In rising toward an upper position, the separator has a motion causing its U-shaped wall portions to progressively flex so that one flat portion is progressively "peeled" or curled away from the flat wall 26 and so progressively uncovers the port 27 to permit correspondingly graduated flow there through.

One obvious limiting case or extension of the U-shape configuration of the flexible marginal portion of the separator can be roughly described as a "J" or "reverse-L" shape.

Such would be the case, for example, if the port 27 were positioned somewhat lower in the side wall 26 and in which the separator then operated in a relatively lower position in its port-closing configuration. In this case, the peeling action of the port-opening by the flexible marginal portion of the separator would still be similar. In some instances, the marginal flexible portion of the separator may change from its "J" or "reverse-L" configuration to the "U, '-shape as the separator moves from a generally lower position to a higher position (as in FIGURE 1).

In lowering from an upper position, the separator motion causes the facing wall to progressively flex to afford an increasing flat wall area progressively covering the port 27 and so progressively throttling flow there through. The flexing marginal portion of the separator deforms or flexes pursuant to the motion of the remaining portion of the separator resulting from pressure differences between the compartments 14 and 1 6. The effective edge portion moves across the port in opening and closing it. Because the vacuum port 27 is uncovered by a progressive peeling action, only a minimal force is required to overcome the force of the vacuum on the port-covering portion of the separator during the port-uncovering process.In part, this is because only an incremental part of the port-covering portion of the separator is moved from the port at a time and it is only the force of the vacuum effective on that small incremental area of this part that tends to resist the peeling. The force of the vacuum effective on the remaining part of the portcovering portion of the separator does not resist further peeling since that portion remaining in contact with the port is supported by the immediate wall surface surrounding the port.

Also, the force required for effecting the peeling of the port-covering portion of the separator during the port-uncovering process may be further reduced by the mechanical advantage associated with the peeling action of the "U"shaped pliable portion. The separator 1 2 accordingly opens and closes or throttles or limits the port 27 and in this fashion controls the pressure within the compartment 1 6 and regulates flow there through.

As shown in plan view in FIGURE 8, the stiffening plates 33 of the separator 1 2 may be arranged eccentrically, leaving a relatively small radial hinge portion of the separator 1 2 at the left-hand margin. The resulting valving or U-shaped flexible portion that sweeps over and throttles the port 27 is radially relatively large. This affords a greater extent of or freedom for flexure of the valving portion of the separator.

The device of FIGURE 1 acts such that the pressure within the second compartment 1 6 is made to correspond to the predetermined or selected value within the first compartment 14. This is done by varying the outflow through the port or passage 24 to the connected vacuum source with resulting pressure changes. If pressure in the second compartment 1 6 is greater than the pressure in the first compartment 14, the plates 33 and 34 together with the surrounding portions of the separator 1 2 are correspondingly moved upwardly. As the separator rises, the overlying part or leg of the U-shaped portion of the separator starts to uncover the port 27 interconnecting the second compartment 1 6 and the vacuum source allowing outflow. This reduces the pressure within the second compartment 16.The then-superior pressure in the first compartment 14 presses the plates 33 and 34 and the separator to descend the outer leg of the U-shaped separator portion partly or totally to cover the port 27, thus throttling the connection to the vacuum source. A pressure balance between the compartments 14 and 16 is so achieved. The desired pressure is thus established through the port 23 in the particular connected volume being regulated.

To improve regulation under some conditions, the atmospheric valve 32 may be cracked open to afford a slight air leak into the lower compartment 1 6. The pressure within the port-23 and the chamber 16 does not then tend to change abruptly or excessively and "hunting" is damped because of the small leakage inwardly from the atmosphere.

The overall performance of one specific embodiment of this device is approximately as illustrated by the graphs in FIGURE 7. These show that for a given pressure selection, the maintenance of the desired pressure in the port 23 and its connected volume is substantially constant over a relatively wide range of quantities of gas flowing from the pressure regulated volume to the vacuum. There is only a slight pressure change or "droop" with greatly increased quantities of gas flow.

An arrangement similar to that of FIGURE 1 is disclosed in FIGURE 2. An upper compartment 41 and a lower compartment 42 of an enclosure are segregated by a marginally flexi ble separator 43 having a limited marginal portion contoured into a shape U-shaped in axial cross-section to define adjacent approximately flat, axially disposed legs. A port 44 in the wall of the upper compartment 41 is connected to a vacuum source 45 under the control of a variable valve 46. A standard or reference pressure in the upper or first compartment 41 is set by a balance between air outflow through the restricted vacuum port 44 and air inflow from the atmosphere through a small port 47. In the lower or second compartment 42 a port 48 is coupled to the volume being pressure regulated. A port 49 in the path of movement of the adjacent separator leg connects to a suitable vacuum source.

An inlet bleed port 50 effects a limited, dampening connection between the second compartment 42 and the atmosphere. Pressure regulation takes place largely as described in connection with the FIGURE 1 device. In response to pressure differentials between the two compartments 41 and 42, the separator 43 moves and thereby effects a variable throttling of the port 49 by the covering and uncovering motion of the U-shaped margin of the separator.

In FIGURE 3, the FIGURE 1 arrangement is extended to provide an enclosure having a number of compartments 51, 52 and 53. The first compartment 51 and the second compartment 52 are divided by a common separator 54, while the second compartment 52 and the third compartment 53 are divided by a common separator 56. There is a standard or set pressure connection 57 from a source (not shown) like the source 22, extending into the first compartment 51. There is a limited atmospheric connection 58 into the third compartment 53. The second compartment 52 has a restricted inlet 59 from the atmosphere and a discharge port 60, like the port 24, leading to a vacuum source. The port 60 is variably blocked by the flexible edge of the separator 54.

The third compartment 53 has an inlet connection 61 from the volume to be pressure regulated and has a vacuum connection 62 variably blocked by the flexible edge of the separator 56. Movement of the separator 54 provides for regulation of the pressure within the second compartment 52 according to the set pressure within the first compartment 51.

In turn, movement of the separator 56 provides for regulation of the pressure within the third compartment 53 according to the pressure in the second compartment 52, following the set pressure in the first compartment 51.

The separator 54 tends to isolate the predetermined or set pressure within the compartment 51 from effects of the motion of the separator 56 and from any sudden pressure changes that may occur within the compartment 53.

In the modification shown in FIGURE 4, an upper, first compartment 66 is formed in an enclosure, including a cup 67. A second, lower compartment 68 is formed in an enclosure cup 69. The two cups 67 and 69 are assembled against an annular gasket 71 acting as a seal. The upper, first compartment 66 has an outlet 72 to a standard vacuum source (not shown) and also has an atmospheric inlet 77 controlled by a valve 78.

The second, lower compartment 68 is provided with a connection 79 to the volume to be pressure regulated and with a passage 81 going to a vacuum source. Within the enclosure formed by the two cups 67 and 69, and in some respects equivalent to the flexible separator 12, for example, is a stiff plate 83 having a pivot hinge 84 connecting one marginal part of the plate 83 to the cup 69. The plate 83 has an appropriately contoured edge or margin 86 opposite the hinge 84 to sweep over and obstruct or uncover the passage 81.

The operation of this device is like that of the FIGURE 2 device, with the plate 83 rising and falling pursuant to differential pressures between the enclosures 66 and 68 and the plate margin 86 changing axial positions to vary the flow through the passage 81.

In a modified form of device as shown in FIGURE 5, there is an enclosure made up of an upper housing 91, a lower housing 92 and an intermediate housing 93. These housings have intervening, flexible separators 94 and 95, respectively. Above the separator 94 there is a first compartment 87 having a duct 88 leading to a source of predetermined pressure acting as a standard for regulation. Below the separator 94 there is a second compartment 89. The separator 94 carries a calibrated weight 96 connected by a fastener 97 to a guide plate 98 on the under side of the separator 94. Stops 100 limit the downward travel of the plate 98 and its connected parts.

A central boss 99 depending from the plate 98 projects loosely through a bore 101 disposed coaxially or centrally of the intermediate housing 93. There is an atmospheric air passage 102 in the intermediate housing 93 leading to a port 103 opening into the bore 101. Flow through the port 103 is governed by the variable position of the boss 99 in aligning a central and a laterally extending passage 104 therein with the port 103. The passage 104 opens into a third compartment 106 in the housing 93 and separated by the separator 95 from a fourth compartment 107 in the housing 92. The compartment 107 has an opening 108 leading to the volume in which the pressure is to be regulated.

The fourth compartment 107 also has a side passage 109 leading to a source of subatmospheric pressure. A branch passage 111 from the subatmospheric passage 109 leads to the third compartment 106. The second compartment 89 and the third compartment 106, although distinct, are not isolated from each other entirely, but have some communication through the small clearance between the bore 101 and the boss 99.

To some extent in all of the above-described modifications, but especially with the FIGURE 5 arrangement and in the physical orientation shown, the use of the calibrated weight 96 establishes a fixed offset between the regulated pressure and the pressure set in the external volume connected to the duct 88.

This offset or bias acts in one direction or the other depending upon whether the device is used upright, as shown, or is used inverted.

During regulation, pressure differences cause corresponding movement of the boss 99 to register more or less of the port 103 and the opposite passage 104. This allows more or less atmospheric air to enter into the third compartment 106. The stops 100 permit misalignment of the port 103 and the passage 104 as the separator 94 moves upwardly from a central position but permit no throttling by downward movement. Since the third compartment 106 is connected to a vacuum exhaust through the passages 109 and 111, the separator 95 is displaced or flexed and varies conmunication between the vacuum connector 109 and the interior of the compartment 107 and also in the volume to be regulated, connected through the opening 108.

In the version shown in FIGURE 6, an enclosure includes an upper cup 116, a lower cup 117, and two intermediate bodies 11 8 and 11 9. These are respectively isolated by separators 121, 122 and 123. There is an opening 124 from a volume in which the pressure is predetermined to a first compartment 126 above the separator 121. Within the compartment 1 26 there is a washer 1 27 connected by a fastener 1 28 to a block 129 abutting both the separators 121 and 122.

The block 129 has a central or axial opening 131 connected by a radial opening 132 to a second compartment 1 33 between the separators 121 and 122. From the compartment 1 33 a passage 1 36 leads to the atmosphere.

On the other side of the separator 1 22 from the block 1 29 is a holding disc 1 37 appropriately fastened in place. Disposed on one boundary of a third compartment 138, there is a passage 1 39 connected to a passage 141 leading to a source of vacuum. The compartment 1 38 is likewise bounded by the separator 1 23 retained by a disc 142 and helping to define a fourth compartment 144. A duct 146 connects the compartment 144 to the volume containing air whose pressure is to be regulated.

In this instance, since the duct 1 24 is connected to a predetermined pressure, the pressure in the first compartment 126 responds accordingly and causes the separator 1 21 to flex upwardly or downwardly, depending upon the pressure below it in the second compartment 1 33. Corresponding responsive motion is imparted by the plate 1 29 to the separator 122, the motion of which variably obstructs the passage 1 36. This changes the pressure within the second and third compartments 1 33 and 1 38 as affected by flow through the passage 39 and the vacuum passage 141. Fluctuations in pressure in the compartments 1 33 and 1 38 cause deflections of the separator 123, in turn variably obstructing an opening 148 between the vacuum source 141 and the fourth compartment 144. A bleed opening 147 between the atmosphere and the compartment 144 is effective to dampen fluctuations in pressure within the compartment 144.

In some installations, the pressure serving as a standard may not be constant, but may vary with time. In such cases, the pressure regulator acts as a pressure follower and changes the regulated pressure according to variations in the standard. Included herein by reference is the priority application, USSN 490674, a copy of which is filed herewith

Claims (44)

1 A pressure regulator comprising an enclosure having a wall, means defining a port in said wall, and a separator mounted to span said enclosure and move therein, said separator having an edge portion adapted to cover and uncover said port as said separator moves.

2. A pressure regulator as in Claim 1 in which said edge portion has at least in part a pair of facing flexible walls adapted to move in a variable U-shaped configuration.

3. A pressure regulator as in Claim 1 or claim 2 in which said edge portion has a "peeling" motion in covering and uncovering said port.

4. A pressure regulator as in any one of the preceding claims in which said wall is a side wall and said separator has an edge adapted to overlie one portion of said side wall to block said port and to be disposed away from said portion of said side wall to leave said port open.

5. A flow controlling device including a wall having a flow port therein, and a movable diaphragm having a rolling edge portion adapted to cover and uncover said port as said diaphragm moves.

6. A pressure regulator comprising an enclosure having a separator having a generally central portion spanning said enclosure and substantially dividing said enclosure into first compartment and a second compartment, means in said enclosure defining a wall extending substantially perpendicularly to said separator and having therein a port opening into said second compartment, said separator having a first portion adapted. to move in a direction substantially parallel to said wall and having a second portion adapted to extend substantially adjacent to said wall, said motion of said first portion causing said second portion to move in relation to said port between a first position substantially blocking said port and a second position leaving said port substantially free, means for supplying fluid to said second compartment, and means effective in said first compartment to subject said separating means to a pressure value at which said separating means regulates flow from said second compartment through said port by the movement of its first portion back and forth according to pressure differences between said first compartment and said second compartment.

7. A device as in Claim 6 including means for subjecting said first compartment and said second compartment to various pressures by gases.

8. A device as in Claim 6 or Claim 7 including means to provide communication between said second compartment and the atmosphere.

9. A device as in any one of claims 6 to 8 in which said central portion of said separator is stiff.

10. A device as in any one of claims 6 to 8 including rigid plates secured on opposite sides of the central portion of said separator.

11. A device as in any one of claims 6 to 8 in which at least a portion of said separator is substantially rigid, and means for articulating said separator and said enclosure at a location substantially opposite said wall port.

1 2. A device as in Claim 11 in which the margin of said separator adjacent said port is minutely spaced from said wall adjacent said port.

1 3. A device as in any one of claims 6 to 1 2 in which said separator has flexible first and second portions, and in which said second portion is flexible and includes two portions facing and movable relative to each other.

14. A device as in Claim 1 3 in which said flexible second portion is substantially Ushape in cross-section.

1 5. A pressure regulator comprising a first cup having a rim, a second cup having a rim facing said first cup, a separator interposed between and meeting the rims of said cups, a side wall included in said second cup and disposed substantially perpendicular to said separator, means defining a port opening through said side wall into said second cup, means included in said separator and adapted to flex between one position covering and blocking said port and another position uncovering and unblocking said port, and means for varying pressures on opposite sides of said separator to move said separator between said positions.

16. A device as in Claim 15 in which opposite sides of said separator are subjected to gases under varying pressures.

1 7. A pressure regulator comprising a first cup having a rim substantially symmetrical about an axis, a second cup having a rim facing said first cup and substantially synmetrical about said axis, a separator interposed between and meeting the rims of said cups, a wall included in said second cup and having at least a portion lying in a direction substantially parallel to said axis, means defining a port opening through said portion of said wall, means defining at least a portion of said separator adapted to flex between a first position abutting said wall and overlying and substantially blocking said port and a second position leaving said port substantially free, means for subjecting said first cup to fluid pressure effective against one side of said separator, and means for subjecting said second cup to fluid pressure effective against the other side of said separator.

1 8. A device as in Claim 1 7 including means for providing a varying gas pressure in said first cup.

19. A separator for use in a pressure regulator comprising a diaphragm, said regulator having a discharge port in one wall of said regulator, said diaphragm having a central portion and an edge portion, said edge portion adapted to move between one position with said edge portion substantially covering and blocking said port and a second position with said edge portion leaving said port substantially free for flow as said central portion moves back and forth with a motion having a component substantially parallel to said wall in the vicinity of said port.

20. A separator as in Claim 1 9 in which at least said central portion of said diaphragm is substantially rigid and is disposed substantially in a plane and said edge portion of said diaphragm is adapted to flex across said port as said central portion moves with said motion.

21. A pressure regulator having a wall, means defining a flow passage extending through a portion of said wall to define a port, and a separator adapted to move back and forth along a direction substantially parallel to said portion of said wall in response to different pressures on opposite sides of said separator, said separator having at least a portion thereof adapted for covering and uncovering said port as said separator moves back and forth along said direction.

22. A pressure regulator comprising an enclosure, a separator having a generally central first portion having movement back and forth along one direction and dividing said enclosure into a first compartment and a second compartment, said separator having a second portion movable with a motion that includes a component different from said movement of said central portion, means for subjecting said first compartment to a gas pressure serving as a basis of regulation, means for admitting gas to said second com partment, and means defining a port for releasing gas from said second compartment and positioned to be blocked and unblocked by said second portion, said port opening to said second compartment through a wall of said enclosure in a location adapted to be covered and uncovered by said second portion, said wall lying in a direction substantially parallel to said direction of motion of said first portion of said separator.

23. A pressure regulator comprising means defining an enclosure extending substantially about an axis and having a side wall approximately parallel to said axis, a separator substantially spanning and movable substantially axially in said enclosure and defining a first compartment and a second compartment therein, means for subjecting said first compartment to pressure, means defining a fluid inlet opening to said second compartment, means opening through said side wall defining a fluid outlet from said second compartment, and blocking means included in said separator and foldable to move parallel to said axis into and out of a position substantially covering said outlet.

24. A pressure regulator comprising an enclosure, a separator having a generally central first portion having movement back and forth in one direction and dividing said enclosure into a first compartment and a second compartment, said separator having a second portion, means for subjecting said first compartment to a gas pressure serving as a basis of regulation, means for admitting gas to said second compartment, and means defining a port for releasing gas from said second compartment and positioned to be blocked and unblocked by said second portion, said port having its opening to said second compartment lying in a wall of said enclosure substantially parallel to said direction of motion of said first portion of said separator.

25. A pressure regulator as in Claim 1 9 in which said second portion is adapted to flex between a first position substantially blocking said port and a second position leaving said port substantially free.

26. A pressure regulator as in Claim 24 or Claim 25 in which said separator is a a diaphragm, at least a portion of said diaphragm being flexible, and means for mounting said diaphragm to move in said enclosure with one flexible portion of said diaphragm adjacent the edge thereof folding over and away from said port as said diaphragm moves.

27. A pressure regulator as in any one of Claims 25 to 26 in which said means for subjecting said first compartment to a gas pressure includes a first passage leading from the atmosphere into said first compartment and includes a second passage leading from a vacuum source into said first compartment.

28. A pressure regulator as in any one of Claims 24 to 27 including a second separator mounted in said enclosure to define a third compartment and making a separation between said second compartment and a third compartment, means for admitting gas to said third compartment, and means for releasing gas from said third compartment.

29. A pressure regulator as in Claim 28 in which said second separator has a generally central first portion having movement back and forth in opposite directions, and in which said means for releasing gas from said third compartment includes a second port, said second port opening through the wall of said third compartment, said wall being substantially parallel to the motion direction of said central portion of said second separator, and said second separator having a second portion being adapted to flex between a first position substantially blocking said second port and a second position leaving said second port substantially free.

30. A device as in Claim 28 or Claim 29 in which at least a portion of said second separator has in cross-section a substantially Ushaped contour with one leg of the U-shaped contour adapted to lie against said side wall in one position of flexure of the separator.

31. A pressure regulator as in Claim 28 in which said second separator has a central first portion movable back and forth along one line, and in which said means for releasing gas from said third compartment includes a second port, said second port opening through the wall of said third compartment, said wall being substantially parallel to said line, and a portion of said second separator being adapted to flex between a first position substantially blocking said second port and a second position leaving said second port substantially free.

32. A pressure regulator as in any of of Claims 28 to 31, including means in said housing defining a port open to said third compartment and to the atmosphere.

33. A pressure regulator as in any one of Claims 28 to 32 including a third separator means for spacing said third separator from said second separator to define said third compartment therebetween, means functioning with said third separator to define a fourth compartment, means for connecting said third compartment to a source of vacuum, and means including said third separator for variably connecting said fourth compartment and said source of vacuum.

34. A pressure regulator comprising an upper housing, an intermediate housing, a first flexible separator interposed between said upper housing and said intermediate housing, a lower housing, a second flexible separator interposed between said intermediate housing and said lower housing, means defining a bore through said intermediate housing and interconnecting an upper compartment below said first separator and a lower compartment above said second separator, means defining an atmospheric passage in said intermediate housing-leading to a port opening into said bore, a boss secured to said first separator and movable in said bore, means defining a passage in said boss adapted to communicate with said atmospheric passage and said lower compartment, a subatmospheric passage in said lower housing through a wall thereof and in a position to be blocked and unblocked by motion of said second separator, and means for connecting said subatmospheric passage and said lower compartment.

35. A device for controlling flow through a port comprising a diaphragm having an edge fold adapted to travel across said port.

36. A device for controlling fluid flow comprising a wall with a port opening therefrom, and a flexible sheet folded upon itself to afford two legs adjacent each other and having a connecting fold, means for disposing one of said legs against said wall, and means for moving the other of said legs to move said fold across said port.

37. A device as in Claim 36 including means for connecting said port to a vacuum.

38. A pressure regulator comprising an enclosure having a port through the wall thereof; a flexible, non-springy partition spanning said enclosure and having means defining a fold contacting said wall; and means solely of a fluid nature operating on opposite sides of said partition for moving said fold across said port.

39. A pressure regulator comprising a hollow enclosure having a port through the wall thereof; a flexible, non-springy member within said hollow enclosure and movable across said port between positions variably restricting said port; and means responsive only to fluid pressure for so moving said flexible member.

40. A pressure regulator comprising a wall having a discharge port there through, a nonspringy sheet adapted to abut said wall and to move variable to obstruct said port, and means without a spring for causing said sheet so to move.

41. A pressure regulator comprising an enclosure, a separator spanning said enclosure and dividing said enclosure into a first compartment and a second compartment, means for subjecting one of said compartments to the influx of fluid, means controlled by said separator for controlling efflux of said fluid from said one of said compartments and so establishing a fluid pressure therein acting toward the other of said compartments, and a weight on said separator acting toward the one of said compartments.

42. A pressure regulator comprising a separator, means for subjecting said separator on opposite sides to different fluid pressures, and a weight on said separator biasing said separator toward one of said sides.

43. A device as in Claim 42 in which said weight is calibrated to afford a predetermined offset to forces acting to displace said separator with an upward component.

44. A pressure regulator substantially as hereinbefore described with reference to the accomapnying drawings.