US3861642A

US3861642A - Fluid control valve

Info

Publication number: US3861642A
Application number: US329573A
Authority: US
Inventors: Gerald E Maddocks
Original assignee: Fram Corp
Current assignee: Siemens Bendix Automotive Electronics Ltd; Bendix Engine Components Ltd; Fram Corp
Priority date: 1973-02-05
Filing date: 1973-02-05
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: AU6444074A; DE2402669A1; IT1007021B; BE810538A; JPS49111039A; FR2216447A1; CA1000588A; BR7400812D0; FR2216447B3; GB1459513A; AR202013A1; ZA74324B

Abstract

A valve for producing an output signal proportional to an input signal, comprising, a pair of chambers having elastomeric diaphragms thereacross, the diaphragms having predetermined proportionally sized areas and the diaphragms spaced from each other and connected by an integral post therebetween, the diaphragms having moveable inner portions flexibly thin about the margins thereof and thickened by said post inwardly of the margins to be relatively rigid therewithin, an input passage communicating with one chamber, and a second input passage and an output passage communicating with the other chamber, said second input passage normally closed by the diaphragm thereadjacent and opened by movement of said diaphragms away therefrom.

Description

United States Patent [1 1 Maddocks 1 Jan. 21, 1975 FLUID CONTROL VALVE Primary ExaminerArnold Rosenthal [75] Inventor: Gerald E. Maddocks, Chatham,

Ontario, Canada [57] ABSTRACT Assigneel Fl'am Corporation, East Providence, A valve for producing an output signal proportional to an input signal, comprising, a pair of chambers having [22] Filed. 5 1973 elastomeric diaphragms thereacross, the diaphragms having predetermined proportionally sized areas and [21] Appl. No.: 329,573 the diaphragms spaced from each other and connected by an vintegral post therebetween, the dia- 52 US. Cl 251 61.1, 123 119 A, 137 100 phragm havmg movable inner Pom"nS flexib'y E Int. CL Fmk 145 about the margins thereof and thickened by said post [58] Field 1 inwardly of the margins to be relatively rigid there- 157/625 5 6 within, an input passage communicating with one i chamber, and a second input passage and an output [56] References Cited passage communicating with the other chamber, said second input passage normally closed by the dia- UNITED STATES PATENTS phragm thereadjacent and opened by movement of 2,376,918 5/1945 Hughes 251/61.1 X aid diaphragms away therefrom. 3,550,629 12/1970 Kreuter 137/625.66 1

15 Claims, 6 Drawing Figures 28 f X/ is 94 84 as 6 9O 96 98 8O 42 3 54- 5e so FLUID CONTROL VALVE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an improved fluid control valve for producing an output signal proportional to an input signal and, more particularly, to such a control valve for use in amplifying the vacuum signal from a carburator venturi in an internal combustion engine to regulate the recirculation valve of an exhaust gas recirculation system in the engine.

2. Description of the Prior Art Such valves, having a large area diaphragm across a low vacuum chamber connected to an engine carburator venturi and, spaced therefrom a smaller area diaphragm across a high vacuum chamber connected to the engines intake manifold, the smaller diaphragm normally closing the passage from the intake manifold and opening the passage on movement toward the low vacuum chamber, have been previously suggested.

Thus, in a prior control valve design, central discs rigidify the larger diaphragm and the smaller diaphragm is sealed to a central rigid member comprising part of a hook washer assembly interconnecting the two diaphragms for common movement thereof. A tension spring for biasing the diaphragms toward the low vacuum chamber is positioned in the low vacuum chamber and is connected on one end to the diaphragm assembly and on the other end to an exteriorly adjustable calibration unit for tension adjustment. The space between the diaphragms is vented, through a filter in a recess in the valve housing, directly to the atmosphere and a valved bleed passage, intermittently operated, communicates through the rigid member, centrally of the smaller diaphragm, from the high vacuum chamber to the space between the diaphragms. An override mechanism is provided in another recess in the valve housing for disabling the control valve when intake manifold vacuum drops below a predetermeined level.

SUMMARY OF THE INVENTION It is a principal object of this invention to provide an improved fluid control valve which minimizes the number of operating parts and the hysteresis effects inherent in such valves. A further object is to provide such a fluid control valve which eliminates the need for calibration of each unit. Another object is to provide an override mechanism in one of the valve chambers which positively shuts down valve operation under predetermined conditions and which simplifies design. Yet another object is to provide, in such a valve, means for compensating for variations in vacuum caused by the condition of the filter in the air intake. Still another object is to simplify the design of such valves for ease of manufacture and assembly thereof.

In general, the invention features in a fluid control valve an integral elastomeric diaphragm member comprising a pair of diaphragms having predetermined proportionally sized areas, one sealingly spanning each of a pair of chambers, and an integral connector extending between and interconnecting the diaphragms. The diaphragms are flexibly thin about their margins and are thickened inwardly of their margins by the post, thereby centrally rigidifying the diaphragms.

In preferred embodiments the diaphragm member includes a restricted open bleed passage from one chamber, through the diaphragm member, to the space between the diaphragms and a vent passage through the valve housing to the space between the diaphragms. A biasing member in one chamber biases the diaphragm toward the other chamber and in the other chamber a sealed piston is biased in the opposite direction by a biasing member having a greater force than the biasing member in said one chamber.

The control valve is used in an internal combustion engine with: the chamber having the larger area diaphragm connected to the carburator venturi; the other chamber connected, by a passage normally closed by the adjacent diaphragm and opened on movement of the diaphragm member away therefrom, to the engine intake manifold via a vacuum reservoir; an output passage from the said other chamber connected to the engine exhaust gas recirculation valve; the vent passage connected to the air passage ahead of the venturi and after the engine air cleaner filter; and the volume behind the sealed piston connected directly to the intake manifold.

Other objects, features and advantages of this invention will be apparent to those skilled in the art from the following detailed description of a preferred embodiment thereof, taken together with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an isometric view of a vacuum control valve embodying the invention;

FIG/2 is a plan view of the valve shown in FIG. 1;

FIG. 3 is an enlarged, sectional view taken along the line 33 of FIG. 1;

FIGS. 4 and 5 are reduced, sectional views, similar to that of FIG. 3, illustrating different operative positions of the valve components; and

FIG. 6 is a schematic view, partly in section, of the valve as used in an internal combustion engine.

DESCRIPTION OF THE PREFERRED EMBODIMENT As shown in FIGS. 1 and 2, the control valve 10 comprises a housing, circular in transverse plane, having cylindrical exterior walls. The housing includes a cap 12, a base 14 and a metal connector collar 16 therebetween. Cap 12 and base 14 are preferably molded from heat resistant organic plastic material.

In greater detail, as shown in FIG. 3, cap 12 has a ho]- low interior closed on the sides by cylindrical side wall 18 and on the end, remote from base 14, by circular, transverse, end wall 20 integral with side wall 18. A lip 22 extends radially outwardly about the periphery of wall 18 at the end thereof opposite end wall 20. Within the interior of cap 12 a cylindrical low vacuum first chamber 24, of predetermined cross-sectional area, extends from lip 22 toward end wall 20. About the periphery of low vacuum chamber 24 and lip 22, a quarter round recess 26 is provided.

A cylindrical override chamber 28, of smaller diameter than and coaxial with low vacuum chamber 24, extends centrally within low vacuum chamber 24 to end wall 20. Coaxially of end wall 20, a cylindrical first locating member 30, having a reduced diameter relative to that of override chamber 28, extends a short distance into override chamber 28, member 30 having a groove 32 extending thereacross.

A low vacuum first input tube 34, located at the peripheral edge of end wall 20 and extending outwardly therefrom, has a first input passage 36 therein communicating with low vacuum chamber 24 through end wall and along and within cylindrical wall 18. Coaxially of override chamber 28, another tube, override tube 38, extending outwardly from end wall 20, has an override passage 40 communicating through end wall 20 with override chamber 28 at the base of groove 32.

Base 14 comprises essentially a cylindrical block having a planar surface 42 facing cap 12 and coaxial thereof, base 14 having a diameter only slightly smaller than that of cap 12. Coaxially of and facing low vacuum chamber 24, a cylindrical high vacuum second chamber 44 is formed in base 14, extending from surface 42 to end wall 46. High vacuum chamber 44 is closed on the end remote from cap 12 by end wall 46 and on the sides by cylindrical side wall 48 integral with end wall 46. A lip 50 extends radially outwardly about the periphery of wall 48 adjacent surface 42. High vacuum chamber 44 has a cross-sectional area proportional, in a predetermined relationship, to that of low vacuum chamber 24, in the preferred embodiment illustrated chamber 44 being smaller than chamber 24.

A vent tube 52, located adjacent the peripheral edge of end wall 46 in base 14 and extending outwardly therefrom has a vent pasage 54 extending through base 14 to surface 42, the portion of passage 54, adjacent surface 42, angled outwardly to open through surface 42 just inwardly of lip 50. Coaxially of high vacuum chamber 44, a high vacuum second input tube 56 extends outwardly of end wall 46 and extends coaxially within high vacuum chamber 44, spaced from the side walls thereof, to a position flush with the plane of surface 42, a second input passage 58 communicating through tube 56. A signal output tube 60, spaced from

tubes

52, 56 located adjacent the peripheral edge of end wall 46 in base 14 and extending outwardly therefrom, has an output passage 62 extending through base 14 and angled inwardly to communicate with the interior of high vacuum chamber 44 through the side thereof adjacent surface 42 and spaced from high vacuum tube 56.

The metal connector collar 16 has ana inwardly directed base flange 64 at one end of the integral cylindrical wall 66 thereof, flange 64 engaging the underside oflip 50 of base 14 opposite the surface 42 thereof. An outwardly directed cap flange 68 axially spaced from flange 64 by and integral with wall 66, underlies the surface of lip 22 of cap 12 facing base 14. An integral portion 70 of flange 68 is bent around lip 22 to the side thereof opposite base 14.

An elastomeric diaphragm member 72 is positioned within housing 10. Diaphragm member 72 includes a first circular, planar diaphragm 74 spanning cap lip 22 across low vacuum chamber 24. A normally inverted U-shaped, flexibly thin bead 76, marginally defining an inner movable portion of diaphragm 72, is provided about the first diaphragm 74 extending toward cap 12, bead 76 positioned in quarter round recess 26 and having a slightly smaller radius of curvature to form the inverted U-shape than the recess 26. The peripheral portion of diaphragm 74 extends radially beyond bead 76 to a solid bead seal 78 about the periphery thereof, seal 78 facing base 14 and positioned between the facing surfaces of cap lip 22 and collar flange 68.

Diaphragm member 72 also includes a second circular, planar diaphragm 80, parallel to diaphragm 74, spanning high vacuum chamber 44, and including a peripheral portion extending beyond high vacuum chamber 44, across a portion of base surface 42, to a solid bead seal 82 about the periphery and radially inwardly of passage 54. Seal 82 faces base 14 and is positioned in an annular groove (not separately numbered) in base surface 42. Second diaphragm is flexibly thin inwardly adjacent the edge of high vacuum chamber 44, marginally defining a moveable inner portion of diaphragm 80. Diaphragm 80 normally is against and closes the passage 58 of tube 56 within high vacuum chamber 44.

First and

second diaphragms

74, 80 are fixedly and rigidly axially spaced from each other and connected together by integral coaxial post 84 extending therebetween. Tube 56 abuts diaphragm 80 opposite post 84. Spaced radially outwardly of tube 56, a right angle passage, restricted unobstructed, continuously open bleed hole 86, extends through second diaphragm 80 and post 84 from high vacuum chamber 44 to the compensator third chamber 88 defined in the space between

diaphragms

74, 88. In the preferred embodiment, bleed hole 86 has a diameter of 0.02 inches opening into high vacuum chamber 44 and a diameter of 0.06 inches opening into compensator chamber 88.

Post 84 extends as a cylinder from second diaphragm 80 about half-way toward first diaphragm 74 and then flares radially outward blending into first diaphragm 74. The diameter of post 84 at diaphragm 80 is about two thirds the diameter of high vacuum chamber 44 and at diaphragm 74 post 84 extends substantially thereacross to adjacent bead 76. Thus, the inner moveable portions of

diaphragms

74, 80, are centrally thickened and rigidified by post 84 inwardly adjacent narrow, flexibly thin annular portions thereof and comprise the major portions of the areas of

diaphragms

74, 80. The flexibly thin portions of

diaphragms

74, 80, and the portion of post 84 flared outwardly, adjacent diaphragm 74, together comprising a major portion of the area of diaphragm 74, are exposed to the compensator chamber 88.

A metal retainer 90 is positioned in compensator chamber 88. Retainer 90 includes a cylindrical wall 94 inwardly adjacent and parallel to wall 66 of collar 16. An integral, outwardly extending flange 94 of retainer 90 extends from one end of wall 92 between collar flnge 68 and fist diaphragm 74 opposite cap lip 22 and abutting the inner periphery of bead seal 78. At the other end of wall 92 an integral, inwardly extending pierced flange 96 overlies second diaphragm 80. outwardly from high vacuum chamber 44, sandwiching second diaphragm 80 between the flange 96 and surface 42 of base 14. Centrally of flange 96, an annular opening 98 is provided through which post 84 of diaphragm member 72 extends. Annular opening 98 is substantially the same diameter as high vacuum chamber 44, in the preferred embodiment 0.02 inches larger, and defines the outer limit of the operative moveable inner portion area of second diaphragm 80 in essentially the same predetermined ratio of area to first diaphragm 74 moveable inner portion area, across the apex of head 76, as the ratio of the areas of the low and

high vacuum chambers

24, 44. In the preferred embodiment illustrated the ratio of the areas of the inner moveable portions of

diaphragms

80, 74 is about one order of magnitude, e.g., 1:14. Opposite the opening of passage 54 through base surface 42, an aperture 100 is provided in flange 96 of retainer 90 for communication of passage 54 with compensator chamber 88.

Retainer 90 functions with collar 16 to fixedly space cap 12 and base 14 a predetermined distance apart, firmly engaging collar flange 64 against base lip 50. Flange 96, together with base surface 42 and second diaphragm 80, including seal 82, renders high vacuum chamber 44 air tight sealingly engaging the peripheral portion outwardly of opening 98. Similarly, low vacuum chamber 24 is rendered air tight by retainer flange 94, and lip 22 sealingly engaging the peripheral portion outwardly of bead 76, seal 78 against the edge of flange 94. Compensator chamber 88 is sealed on one side by the same sealing means which renders low vacuum chamber 24 air tight and on the other side is sealed by the collar flange 64 against base lip 50.

Within high vacuum chamber 44, a biasing member, compression spring 102, is provided without about 56. Spring 102 bears against base end wall 46 and against second diaphragm 80, opposite post 84 urging second diaphragm 80 away from its normal position closing passage 58 in tube 56.

Secured in low vacuum chamber 24 is override piston, diaphragm 104, extending coaxially of and across a substantial portion of the side of first diaphragm 74 opposite post 84. Override diaphragm 104 includes a generally cylindrical inner wall 106, integral therewith, extending to cap end wall 20 and having an accordian pleat or rib 108 formed therein to permit axial flexure of inner wall 106 for movement of override diaphragm 104 toward and away from first diaphragm 74. Adjacent end wall 20, inner wall 106 is turned outwardly to form an integral cylindrical outer wall 110 against cap side wall 18, outer wall 110 molded to metal retainer ring 112 which presses outer wall 110 against cap side wall 18 thereby sealingly defining override chamber 28 in low vacuum chamber 24.

Facing first locating member 30 and coaxially thereof within override chamber 28, integral with override diaphragm 104, is short cylindrical second locating member 1 14 normally spaced from first locating member 30 and having the same diameter thereas. A biasing member, override compression spring 116, is positioned within override chamber 28 coaxially of and about locating

members

30, 114. Override spring 116 bears against end wall 20 and override diaphragm 104 urging override diaphragm 104 toward diaphragm member 72. Override spring 116 has a greater spring force than spring 102 in high vacuum chamber 44.

Control valve is shown in FIG. 6 as used to control the exhaust gas recirculation system of an internal combustion engine 200. As shown in FIG. 6, engine 200 includes an intake manifold 202 within which a relatively high vacuum is generated during engine operation.

Carburator 204 is mounted on intake manifold 202 and communicates with the interior thereof via passage 206. Within carburator 204 is carburator venturi 208 and, downstream thereof a throttle plate 210. A relatively low vacuum, proportional to the fuel and air mixture entering the engine 200 via intake manifold 202, is generated during engine operation at the throat of venturi 208.

Upstream of carburator 204 is air cleaner 212 having an air intake 214 and a filter 216. Downstream of filter 216, upstream of venturi 208, air cleaner 212 has a passage 218, communicating with carburator 204 and passage 206, through which filtered air passes to carburator 204. A small vacuum, due to the pressure drop across filter 216, is generated during engine operation which increases the vacuum at venturi 208 and in manifold 202. The vacuum, due to the pressure drop across filter 216, is not constant, however, increasing as the filter 216 becomes contaminated thereby increasing the pressure drop.

Also mounted on intake manifold 202 is exhaust gas recirculation valve 220. Recirculation valve 220 communicates with the interior of intake manifold 202 via passage 222. Recirculation valve 220 also communicates with and connects passage 222 of intake manifold 202 with one end of an exhaust gas passage 224, within the wall of intake manifold 202, extending from the engine exhaust manifold (now shown). Recirculation valve 220 includes a valve member 226 for opening and closing exhaust gas passage 224 and also includes a vacuum motor 228 connected to valve member 226 for actuation thereof in response ro a vacuum signal, opening exhaust gas passage 226 in response to a high vac uum signal and closing exhaust gas passage 226 in response to a relatively lower vacuum signal.

As shown in FIG. 6, low vacuum tube 34 is connected by tube 230 to venturi 208, communicating low vacuum chamber 24 therethrough with the throat of carburator venturi 208. Override tube 38 is connected by tube 232 to intake manifold 202, communicating override chamber 28 therethrough directly with the interior of intake manifold 202. High vacuum tube 56 is connected by branch tube 234, which in turn is connected to tube 232, to intake manifold 202, communicating high vacuum chamber 44 therethrough with the interior of intake manifold 202. Signal output tube 60 is connected by tube 240 to vacuum motor 228 of recirculation valve 220, communicating high vacuum chamber 44 therethrough with vacuum motor 228. Compensator tube 42 is connected by tube 242 to air cleaner passsage 218, communicating compensator chamber 88 to passage 218 downstream of filter 216 and upstream of venturi 208.

A vacuum reservoir 236 is provided in branch tube 234, upstream of high vacuum chamber 44. Upstream of reservoir 236, in branch tube 234, is a one way check valve 238 for admitting vacuum to reservoir 236 and for preventing immediate reduction of vacuum therein upon reduction of intake manifold 202 vacuum.

In operation, as shown in FIGS. 4 and 5, the vacuum from intake manifold 202, communicated to override chamber 28, is normally greater than the biasing force of spring 1 16, resulting in the movement of override diaphragm 74 toward cap end wall 20, away from first diaphragm 74, rendering diaphragm member 72 operative. The opening of passage 40 from override tube 38 into override chamber 28 at the base of slot 32 in locating member 30 prevents the blocking of passage 40 if override diaphragm contacts locating member 30, thereby maintaining override chamber in constant communication with intake manifold 202.

First diaphragm 74 is affected by the vacuum in low vacuum chamber 24 and by the pressure in compensator chamber 88. Second diaphragm is affected by the vacuum in high vacuum chamber 44 and by the pressure in compensator chamber 88. Due to their rigid interconnection and their relative rigidity centrally, when a vacuum is applied to first diaphragm 74, the force applied to the first diaphragm 74 is transmitted by post 84 to the second diaphragm 80. Due to the different areas of

diaphragms

74, 80, equilibrium of forces applied thereto is achieved when the ratio of the vacuum in high vacuum chamber 44 to the vacuum in low vacuum chamber 24 is directly proportional to the area of the first and

second diaphragms

74, 80.

Thus, assuming an initial equilibrium, when the vacuum communicated from carburator venturi 208 to low pressure chamber 24 is increased, upsetting the equilibrium between low and

high vacuum chambers

24, 44, first diaphragm 74 moves toward cap end wall 20, moving with it second diaphragm 80 and opening high vacuum tube 56 to high vacuum chamber 44, as shown in FIG. 4. Intake manifold vacuum from reservoir 236 thereupon enters high vacuum chamber 44 and is communicated through signal output tube 60 to vacuum motor 228 to move valve member 226 to a more open position admitting more exhaust gas through

passages

224, 222 to intake manifold 202. When equilibrium is restored, first and

second diaphragms

74, 80 will return to their normal positions, second diaphragm 80 closing tube 56, as shown in FIG. 5.

The high vacuum in chamber 44 is continuously bled through bleed hole 86 to compensator chamber 88 which is maintained at a higher pressure, i.e., lower vacuum, than both low and

high vacuum chambers

24, 44. Thus, when equilibrium is attained, it is continually unbalanced by the bleeding of vacuum from chamber 44 causing

diaphragms

74, 80 to move and open tube 56 to restore equilibrium, after which diaphragms 74, 80 will move to close tube 56. Moreover, if the vacuum in low vacuum chamber 24 is reduced to a value lower than the existing equilibrium value, second diaphragm 80 remains closed and vacuum is bled from high vacuum chamber 44 until equilibrium is restored at the lower value reducing vacuum communicated to vacuum motor 228 to move valve member 226 to a more closed position restricting exhaust gas flow to intake manifold 202. As vacuum is further bled from chamber 44,

diaphragms

74, 80 will move to open and close to maintain equilibrium, as above described.

Spring 102 functions to provide a predetermined minimum vacuum within high vacuum chamber 44. Thus, with no vacuum in low vacuum chamber 24, spring 102 will nevertheless move second diaphragm 74 to open tube 56 admitting vacuum to chamber 44 until the vacuum is sufficient to overcome the biasing force of spring 102 moving second disphragm 74 to close tube 56.

Thus a minimum vacuum value is maintained in high vacuum chamber 44 and communicated to vacuum motor 228. Above the minimum vacuum, the amount of vacuum in chamber 44 and communicated to vacuum motor 228 is proportional to the vacuum at carburator venturi 208 communicated to low vacuum chamber 24.

The connection of compensator chamber 88 to passage 218 of air cleaner 212, downstream of filter 216, serves two functions. First, it provides a source of clean filtered air for the bleed of vacuum from high vacuum chamber 44. Second, it applies the vacuum, resulting from the pressure drop across filter 216, to the exposed sides of

diaphragms

74, 80 opposite

vacuum chambers

24, 44. Thus, the vacuum in compensator chamber 88 tends to cancel the effect of the additional vacuum in low vacuum chamber 24 resulting from pressure drop across filter 216, principally affecting the venturi vacuum and communicated by venturi 208 to chamber 24.

Additionally, this inherently corrects for changes in vacuum, resulting from the pressure drop across filter 216, as filter 216 becomes dirty thereby increasing the pressure drop. Thus the net force on

diaphragms

74, 44 is essentially the true value of the vacuum at venturi 208 and in manifold 222 unaffected by the pressure drop across filter 216. The change in vacuum in compensator chamber 88 does not substantially affect second diaphragm 80, because its value is low relative to the vacuum in chamber 44.

When the vacuum in intake manifold 202 falls, check valve 238 in branch tube 234 closes maintaining vacuum at a high level in vacuum reservoir 236 for use by control valve 10. Check valve 238 will reopen when the vacuum in reservoir 236 falls to the level of vacuum in intake manifold 202 or when the vacuum in intake manifold 202 is raised to that in reservoir 236.

If, however, the vacuum in intake manifold 202 falls below the predetermined biasing force of spring 116 in override chamber 28, override diaphragm 104 will move against first diaphragm 74. The effective area of first diaphragm 74 in low vacuum chamber 24 is immediately reduced and the force of override spring 116 together with the vacuum in high vacuum chamber 44 moves diaphragm member 72 toward base 14, closing second diaphragm against tube 56, as shown in FIG. 3. Thus, as vacuum in chamber 44 is bled through bleed hole 86, the signal to vacuum motor 228 is reduced closing valve member 226 to stop circulation of exhaust gas to intake manifold 202. The same sequence occurs when engine operation is terminated.

Thus, in normal engine operation, control valve 10 puts forth a signal to exhaust gas recirculation valve 220, above a predetermined minimum value, which is proportional to the vacuum at carburator venturi 208. The flow of exhaust gas to intake manifold 202 is, therefore, proportional to the flow thereto of fuel air mixture. The signal is unaffected by most variations in vacuum in intake manifold 202. Hence, during engine idling or deceleration, when vacuum in intake manifold 202 is at its highest levels but venturi vacuum is low, the signal to recirculation valve 220 is attenuated to reduce the flow of exhaust gas to intake manifold 202. However, when manifold pressure falls below a predetermined value, as during full throttle acceleration when venturi vacuum is high, the override diaphragm will operate to shut down the system and close recirculation valve 220.

Hysteresis is minimized in the control valve by virtue of the integral diaphragm member design minimizing the number of operative and connecting parts. The continuously open bleed passage contributes to the minimizing of hysteresis effects. The design further eliminates the need for unit calibration. The override mechanism, in the low vacuum chamber, provides a simple and positive means for disabling the valve. Compensation for variations in venturi vacuum caused by the filter condition is provided. The simplified valve design eases the manufacture and assembly thereof.

Other embodiments of this invention will occur to those skilled in the art which are within the scope of the following claims.

What is claimed is:

1. In a fluid control valve comprising:

a housing enclosing a volume and defining, therewithin, a pair of spaced apart chambers opening toward each other, the first of said chambers at one end of and the second of said chambers at the other end of said enclosed volume;

a first diaphragm across said first chamber and a second diaphragm across said second chamber, said diaphragms spaced apart, connected to each other and having predetermined proportionally sized areas;

a first input passage communicating through said housing with said first chamber and spaced from said first diaphragm; and

a second input passage and a separate output passage, each communicating through said housing with said second chamber, said output passage spaced from said second diaphragm and said second input passage extending to said second diaphragm and normally closed thereby, said second input passage open with said second diaphragm moved toward said first chamber;

that improvement characterized in comprising:

an integral elastomeric diaphragm member positioned between and closing said chambers, said diaphragm member comprising said first and second spaced apart diaphragms, each said diaphragm spanning one of said chambers and having an outer peripheral portion fixedly and sealingly secured peripherally to one of said chambers and each said diaphragm having a moveable inner portion and a flexibly thin portion about the margin thereof adjacent said outer peripheral portion, said flexibly thin portion marginally defining said moveable inner portion and integrally connecting said inner and outer portions and said moveable inner portion moveable toward and away from said chambers, and said diaphragm member also comprising a connector post extending between and integrally connected to and connecting said diaphragms on the adjacent sides thereof, said post extending transversely across each said diaphragm moveable inner portion from inwardly adjacent said flexibly thin portion, said post thickening and rigidifying said moveable inner portion inwardly adjacent said flexibly thin portion, said control valve further including a vent passage communicating through said housing with a third chamber defined within said housing by said housing and the space between said diaphragms and further including a bleed passage extending through said diaphragm member from said second chamber to said third chamber at a position spaced from said second input passage.

2. In the control valve claimd in claim 1, the improvement further characterized in comprising a biasing member in said second chamber contacting the said second diaphragm and biasing said diaphragm member toward said first chamber.

3. In a fluid control valve comprising:

an integral elastomeric diaphragm member positioned between and closing said chambers, said diaphragm member comprising first and second spaced apart diaphragms, said disphragms respectively spanning said first and second chambers and having an outer peripheral portion fixedly and sealingly secured peripherally to one of said chambers and each said diaphragm having a moveable inner portion and a flexibly thin portion about the margin thereof adjacent said outer peripheral portion, said flexibly thin portion marginally defining said moveable inner portion and integrally connecting said inner and outer portions and said moveable inner portion moveable toward and away from said chambers, and said diaphragm member also comprising a connector post extending between and integrally connected to and connecting said diaphragms on the adjacent sides thereof, said post extending transversely across each said diaphragm moveable inner portion from inwardly adjacent said flexibly thin portion, said post thickening and rigidifying said moveable inner portion inwardly adjacent said flexibly thin portion, the area of said first diaphragm inner moveable portion greater than the area of said second diaphragm inner moveable portion;

a second input passage and a separate output passage, each communicating through said housing with said second chamber, said output passage spaced from said second diaphragm and said second input passage extending to said second diaphragm and normally closed thereby, said second input passage open with said second diaphragm moved toward said first chamber,

that improvement characterized in comprising:

a piston in said first chamber extending transversely of siad moveable inner portion of said first diaphragm to a position inwardly spaced from said flexibly thin portion of said first diaphragm, a tubular, axially flexible wall sealingly connected at one end thereof to said piston and at the other end thereof, remote from said first diaphragm, to said housing, thereby defining, with said piston and said housing, an override chamber, an override biasing member in said override chamber contacting said piston, said override biasing member biasing said piston toward said first diaphragm, and an override passage communicating through said housing with said override chamber.

4. In the control valve claimed in claim 1, the improvement further characterized in comprising a restricted open passage forming said bleed passage.

5. In the control valve claimed in claim 1, the improvement further characterized in comprising said first and second diaphragms, on the sides thereof facing said first and second chambers, respectively, and opposite said post, comprising planar surfaces parallel to each other, the area of the moveable inner portion of said second diaphragm comprising a minor fraction of the area of the movable inner portion of said first diaphragm, said post integral with said diaphragms across said moveable inner portions thereof inwardly of said flexibly thin portions thereof, and said post comprising a first portion extending generally angularly inwardly from said first diaphragm and toward said second diaphragm and having an area, in a plane spaced from said first diaphragm and parallel to said diaphragm surfaces, smaller than the area of said moveable inner portion of said second diaphragm.

6. In the control valve claimed in claim 5 the difference in said areas of said moveable inner portions of said diaphragms being on the order of one order of magnitude.

7. In the control valve claimed in claim 4, the improvement further characterized in comprising said post having a surface extending generally transversely outwardly adjacent said first diaphragm, the combined transverse areas of the flexibly thin portion of said first diaphragm moveable inner portion and of said transversely extending surface of said post, in a plane parallel to said first diaphragm, being exposed to said third chamber and comprising a major fraction of said area of said first diaphragm inner moveable portion.

8. In the control valve claimed in claim 1, the improvement further characterized in comprising a cap member and a base member comprising said housing, said members connected together enclosing said volume, said cap member comprising a cap end wall at said housing one end and a cap side wall extending therefrom toward said base member and having an inner annular wall, extending from said cap end wall toward said base member, defining with said cap end wall said first chamber, said base member comprising a base end wall at said housing other end and a base side wall extending therefrom toward cap member and having an inner annular wall, extending from said base end wall toward said cap member, defining with said base end wall said second chamber, said moveable inner portions of said diaphragms substantially coextensive and coaxial with said chamber annular walls.

9. In the control valve claimed in claim 8, the improvement further characterized in comprising a generally tubular collar connector connected to and joining together said cap and base members said outer peripheral portion of said first diaphragm sealingly secured between said collar connector and said cap side wall.

10. In the control valve claimed in claim 8, the improvement further characterized in comprising a retainer member having a radially extending pierced flange overlying the outer peripheral portion only of said second diaphragm, outwardly of said moveable inner portion thereof, and overlying said base member under said diaphragm, sandwiching said second diaphragm outer peripheral portion therebetween, and also having a tubular wall extending to and against said first diaphragm opposite the portion of said cap side wall facing said base member and secured thereat, said retainer spacing said cap and base members and sealingly securing said second diaphragm.

11. in the control valve claimed in claim 10, said first, second and third chambers of generally cylindrical configuration, the improvement further characterized in comprising said first and second diaphragms, on the sides thereof facing said first and second chambers, respectively, and opposite said post, comprising planar surfaces parallel to each other, the area of the moveable inner portion of said second diaphragm comprising a minor fraction of the area of the moveable inner portion of said first diaphragm, said post integral and coaxial with said diaphragms across said moveable inner portions thereof inwardly of said flexibly thin portions thereof, and said post comprising a first portion extending generally angularly inwardly from said first diaphragm and toward said second diaphragm and having an area, in a plane spaced from said first diaphragm and parallel to said diaphragm surfaces; smaller than the area of said moveable inner portion of said second diaphragm.

12. In the control valve claimed in claim 11, the improvement further characterized in comprising a coil compression spring in said second chamber about said second input passage, extending between said base end wall and said second diaphragm, biasing said diaphragm member toward said first chamber.

13. In the control valve claimed in claim 11, in which said second input passage comprises a tube coaxial of said second chamber, extending therewithin from said base end wall to said second diaphragm opposite said post, the improvement further characterized in comprising a piston in said first chamber extending parallel to said moveable inner portion of said first diaphragm to a position inwardly spaced from said flexibly thin portion of said first diaphragm, a tubular, axially flexible wall sealingly connected at one end thereof to said piston and at the other end thereof, remote from said first diaphragm, to said housing, thereby defining with said housing an override chamber, an override coil compression spring in said override chamber, extending between said cap end wall and said piston, biasing said piston toward said first diaphragm, and an override passage communicating through said housing with said override chamber.

14. In the control valve claimed in claim 13, in which said second input passage comprises a tube coaxial of said second chamber, extending therewithin from said base end wall to said second diaphragm opposite said post, the improvement further characterized in comprising a second coil compression spring in said second chamber, about said second input passage, extending between said base end wall and said second diaphragm, opposite said post, biasing said diaphragm member toward said first chamber, the biasing force of said override spring being greater than that of said second spring.

15. In the control valve claimed in claim 14, the improvement further characterized in comprising a generally cylindrical locating member integral with said cap end wall extending therefrom within said override chamber toward said piston and spaced from said piston, one end of said override spring positioned about said locating member, and a transverse groove extending across said locating member, said override passage opening to the base of said groove.

CER'FTHWCATE 0 CGRELEI'EVEGN Patent No. 3, 861,642 Dated January 21, 1975 UNETED S'EATEC PA'FER'E EFZCE I l f i E Inventor(s) Gerald E Maddocks 3 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 3, line 42, "ana" should be --an-.

C01. 4, line 42, "94" should be -92-;

line 46, "flnge" should be --f1ange--.

Col. 5, line 18, "without about 56" should be --about tube 56 C01. 6, line 15, "now" should be not-;

line 19, "T0" should be -to-.

C01. 9, line 50, "claimd" should be -claimed-.

C01. 10, line 33, Y'siad" should be --said-.

Claims

1. In a fluid control valve comprising: a housing enclosing a volume and defining, therewithin, a pair of spaced apart chambers opening toward each other, the first of said chambers at one end of and the second of said chambers at the other end of said enclosed volume; a first diaphragm across said first chamber and a second diaphragm across said second chamber, said diaphragms spaced apart, connected to each other and having predetermined proportionally sized areas; a first input passage communicating through said housing with said first chamber and spaced from said first diaphragm; and a second input passage and a separate output passage, each communicating through said housing with said second chamber, said output passage spaced from said second diaphragm and said second input passage extending to said second diaphragm and normally closed thereby, said second input passage open with said second diaphragm moved toward said first chamber; that improvement characterized in comprising: an integral elastomeric diaphragm member positioned between and closing said chambers, said diaphragm member comprising said first and second spaced apart diaphragms, each said diaphragm spanning one of said chambers and having an outer peripheral portion fixedly and sealingly secured peripherally to one of said chambers and each said diaphragm having a moveable inner portion and a flexibly thin portion about the margin thereof adjacent said outer peripheral portion, said flexibly thin portion marginally defining said moveable inner portion and integrally connecting said inner and outer portions and said moveable inner portion moveable toward and away from said chambers, and said diaphragm member also comprising a connector post extending between and integrally connected to and connecting said diaphragms on the adjacent sides thereof, said post extending transversely across each said diaphragm moveable inner portion from inwardly adjacent said flexibly thin portion, said post thickening and rigidifying said moveable inner portion inwardly adjacent said flexibly thin portion, said control valve further including a vent passage communicating through said housing with a third chamber defined within said housing by said housing and the space between said diaphragms and further including a bleed passage extending through said diaphragm member from said second chamber to said third chamber at a position spaced from said second input passage.

3. In a fluid control valve comprising: a housing enclosing a volume and defining, therewithin, a pair of spaced apart chambers opening toward each other, the first of said chambers at one end of and the second of said chambers at the other end of said enclosed volume; an integral elastomeric diaphragm member positioned between and closing said chambers, said diaphragm member comprising first and second spaced apart diaphragms, said disphragms respectively spanning said first and second chambers and having an outer peripheral portion fixedly and sealingly secured peripherally to one of said chambers and each said diaphragm having a moveable inner portion and a flexibly thin portion about the margin thereof adjacent said outer peripheral portion, said flexibly thin portion marginally defining said moveable inner portion and integrally connecting said inner and outer portions and said moveable inner portion moveable toward and away from said chambers, and said diaphragm member also comprising a connector post extending between and integrally connected to and connecting said diaphragms on the adjacent sides thereof, said post extending transversely across each said diaphragm moveable inner portion from inwardly adjacent said flexibly thin portion, said post thickening and rigidifying said moveable inner portion inwardly adjacent said flexibly thin portion, the area of said first diaphragm inner moveable portion greater than the area of said second diaphragm inner moveable portion; a first input passage communicating through said housing with said first chamber and spaced from said first diaphragm; and a second input passage and a separate output passage, each communicating through said housing with said second chamber, said output passage spaced from said second diaphragm and said second input passage extending to said second diaphragm and normally closed thereby, said second input passage open with said second diaphragm moved toward said first chamber; that improvement characterized in comprising: a piston in said first chamber extending transversely of siad moveable inner portion of said first diaphragm to a position inwardly spaced from said flexibly thin portion of said first diaphragm, a tubular, axially flexible wall sealingly connected at one end thereof to said piston and at the other end thereof, remote from said first diaphragm, to said housing, thereby defining, with said piston and said housing, an override chamber, an override biasing member in said override chamber contacting said piston, said override biasing member biasing said piston toward said first diaphragm, and an override passage communicating through said housing with said override chamber.