CA1043218A - Vap or recovery valve - Google Patents

Abstract

VAPOR RECOVERY VALVE

ABSTRACT OF THE DISCLOSURE

A flow control valve particularly useful for a vapor recovery system of a gasoline station. Gasoline and gasoline vapor flow through separate passages in the valve. A restriction (venturi) is provided in the gasoline passage so that a pressure differential will be produced in the passage as a function of the rate of flow of gasoline passing therethrough. A first diaphragm carrying a valve element which controls the flow of fluid through the vapor passage is responsive to said pressure differential so that the flow rate of vapor passing through the valve will be proportional to the flow rate of gasoline. In each of two alternative embodiments, another diaphragm responsive to gasoline pressure is ganged to the valve to compensate for gasoline pressure variations. In a further embodiment, the vapor control valve operates in an "on-off" mode so that a maximum vapor "draw back" is effected whenever gasoline flow of any magnitude is extant.

Description

~043~18 VAPOR RECOVERY VALVE

BACKGROUND OF THE INVENTION
The present invention relates generally to a flow control valve and, more particularly, to a valve for maintaining the fluid flow rate in a first line at least proportional to the fluid flow rate in a second line.
The present invention will be described herein as being a par~
of a gasoline stat~on vapor recovery system. However, it will be appreciated that the invention may find numerous applications, wherever ~ -it is necessary to maintain the rate of flow of fluid in one line at least proportional to the rate of flow of fluid in another line. The valve may be utilized for controlling the flows of two liquids, two gases, or a gas and a liquid.
Recent Federal regulations require that gasoline stations be pro-vided with vapor reoovery systems. In such a system, gasoline vapor collected in an automobile gasoline tank, during filling oi the tank with gasoline, is drawn thereErom through a suction line into the gasoline dispensing unit or pump. A blower (pump) conveys the vapor from the unit to a condenser, where it is condensed and the condensate is returned to a gasoline storag~ tank. The purpose of such vapor recovery system is to minimize the escape of gasoline vapors into the atmosphera and, hence, prevent aonsequent air pollution.
It is desirable that a flow control valve be employed in the vapor line of the vapor recovery system which will control the flow of vapor from the automobile gasoline tank at least proportional to the flow of gasoline into the tank. At the present time, this is accomplished by the use of either two solenoid valves or a single soleno~d valve combined with ",~
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10~3Z18 a flow responsive switch. Because the valves are electrically operated, they must be explosion-proof, which adds considerably to their cost. Also, the sole-noid valves do not inherently modulate. Thus, it has been necessary to elec-' trically modulate the solenoid valves to obtain the approprlate control function.
Such modulation, however, cor~siderably shortens the life of the solenoid valves, and is difficult to attain with any reasonable precision.
' - Therefore, what is needed and constitutes the principal object of the ~
present invention is an improved flow control valve for.use in a gasoline station vapor recovery system or the like. The valve should be simple in construction, automatically modulate or switch, and not require electrically controlled sole-noids or switches'which add to the expense of presently known flow control valves.
:, SU~1ARY OF THE INVENTION
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. According to one aspect of the present invention, there is provided a ` flow control valve for maintaining the fluid flow rate in a first line propor-tional to the fluid Plow rate in a second line comprising: a valve housing hav-;, ing first and second passages therethrough, said first passage being adapted to be coupled to said first line and said second passage being adapted to be coupled I to said second line; a restriction in said second passage for producing a pressure difEerential propoxtional to the rate of flow o~ fluid passing through said second ..
line~ a first cavity in said housing divided into first'and second sections by amovable member; firqt means providing flow communication between said first cavity :
section and said restriction; second means providing flow communication between :, said second cavity section and an unrestricted portion of said second passage ' whereby said movable member is subjected to said pressure differential; a valve :325 seat formed in said first passage; and a valve element in said secon'd cavity sec- ~.
tion fixed to said movable member and positioned to close said valve seat, said valve element shifting away from said valve seat in response to said pressure differential whereby the rate of flow o~ fluid passincJ through said first line ~i will be a predetermined function of the rate of flow of fluid passing through said second line.
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~.~43Z18 According to another aspect of the present invention, there is pro-vided a gasoline vapor recovery system for gasoline delivery to a vented tank, said system comprising: a liquid gasoline line; a gasoline vapor line; a liquid gasoline velocity sensor connected from said liquid gasoline line; and control means connected from said sensor to said vapor line to increase and de-ereasa the vapor veloeity in said vapor line as said liquid gasoline velocity increases and decreases in said liquid gasoline line, respeetively.
BRIEF DESCRIPTION OF THE DRAWINGS
In the aceo~panying drawings which illustrate exemplary embodimentS
of the present invention:
Fig. 1 is a schematic illustration of a simplified form of a ~ :
gasoline station vapor recovery system; - '~
Fig. 2 is a sectional view of a simplified form of a flow con- -trol valve for use in the system illustrated in Fig. 1, and constructed in aecordanee with the present invention;
Fig. 3 is a seetional view of a flow eontrol valve aceording to the invention, having integral eompensation for gasoline pressure varia-tion9i Fig. 4a is a first sectional view of a ~urther embodiment;
~, 20 Fig. 4b is a seeond seetional vlew oE the em~odiment of Fig. 4a; and Fig. 5 is a vertieal seetional view, partly in elevation, of , . . . .
j an alternative embodiment of the present invention.
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to Fig. 1 in dstail, the numeral 10 generally designates a gasoline station recovery system including a gasoline storage tank 12 and a dispensing pump 14. A line 16 connects the tank 12 to a flow control valve 18 within the pump unit 14. A second line 20 in communication with the line 16 through the valve 18 terminates in a conventional nozzle 22 which is shown inserted within the gas tank of an automobile 24. A vapor line 26 also extends from the valve 18 to the nozzle 22 . The end of the line 26 extends into the gas tank when the `~ 10 nozzle is mounted therein for withdrawing vapor from the space above the gasoline in the tank. A second vapor line 28 in communication with the line 26 through the valve 18 is connected to a condenser 30~ A line 32 extends from the condenser back to the storage tank 12. A pump 34 is . ~ .

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provided in the line 16 for pumping gasoline from the tank 12 through the line 16, flow control valve 18 and the line 2~ to the nozzle 22. A blower 35 is provided in the line 28 for creating a partiea vacuum which draws vapor from the automobile gasoline tank through the line 26, control valves 18 and conveys the same to the condenser 30. There the vapor condeses and the condesate returns to the storage tank 12 via the line 32. The vapor recovery system described so far is entirely conventional and does not include ~;
; the present ivention.
According to the present inveniton, there is pro-vided, simplified, and inexpensive flow control valve assembly 18, shown (typically) in detail in Fig. 2.
The valve comprises a housing 36 having a pair of pas-sages 38 and 40 extending therethrough. The housing 36 may be ~ormed of an assembly of metal parts, machined, cast or combination of these, as will be seen.
! The passage 38 is connected to the lines 16 and 20 while the passa$e ~0 is connected to the lines 26 and . . '~
28 of the vapor recovery system illustrated in Fig. 1 The housing 36, as illustrated, is comprised of three separate parts, an upper par-t 42, a lower part 44 and -;
~ intermediate part 46. A cylindrical recess 48 is J formed in the lower portion of the upper housing part 42. A second complementary recess 50 is formed in the '`! .
in the upper portion of the intermediate housing part 46. The two recesses 48 and 50 coopera1e to define a cylindricaI cavity 52 between the passa~es 38 and 40.
A slexible diaphragm ~of gasoline resistant rubber ~1 or thelike ) 54 is interposed between the upper part 42 and intermediate part 46 of the housing. This ,:, ~,~, .-,;:.
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`~ A vertical bore 58 extends from the restriction 56 to ; the space in cavity 52a above the diaphragm 54. A
second bore 60 extends from an unrestricted portion of the passage 38 to the lower face of the upper houslng part 42. This bore could be on ~'. .

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321~ -either side of restriction 56. An opening 62 is formed ~-inthe diaphragm 54 aligned with the bore 60. A passage 64 aligned withthe bore 60 extends from the uppers surface of the intermediate housing part 46 to the recess 52b thereby providing flow communication between an unrestricted portion of the passage 38 and the space in the cavity 52 below the diaphragm 54.
As will be appreciated, as fluid flows -through the passage 38 the restriction 56 will~create a ;, pressure differential which is dependent upon the flo rate of fluid passing through the passage in accord- ~, ance with the well known venturi priniple. Obviously, the prssure in the recess 52b below the kiaphragm 54 will be greater than the pressure in the recess 48 ;
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above the diaphragm so that the pressure differential will act upon the diaphragm 54 to lift the same up- ~
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wardly as viewed in Fig. 2.
A valve element 66 is coaxially positioned within ~
the cavity 52. The upper end of the valve element is ~ -formed with a mouting disc 68 which is fixed and sealed to the diaphragm 54. A spring 70 in the recess 48 acts upon the disc 68 to urge the valve element 66 in the downward direction. The spring 70 provides only ji enough force to bias the valve clsoed in the quiescent conditinn, but not enough to significantly resist the differential pressure on opposite sides of 54 during gasoline flow.
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A bore 72 extends vertically downwardly from the cavity 52 into the vapor passage 40. A flange 74 formed in the housing ex-tends inwardly into the bore 72. The flange joins a generally vertically extending wall 76 which extends as a barrier across the passage " . ' ': '.', ~3'~i~

40. A bore 78 extends vertically through the flange 74 coaxial with the axis of the cylindrical cavity 52. The edge of the flange 74 surrounding the upper end of the bore 78 forms a valve seat 80. The valve element 66, which is coaxial with the axis of the cavity 52 and the bore 78, is formed at its lower end with a conical member 82 which engages the sear 80 under the biasing force of -.: ~ ~ , .

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the spring 70 to normally prevent the flow of fluid through the passage 40. A second flexible rubber diaphragm 84 is interposed between the intermediate housing part 46 and lower part 44. The lower end of the valve element 66 is formed with a flange 86 above :
the conical portion 82. This flange is sealed to the diaphragm 84. The diaphragm 84 thus prevents fluid introduced into the cavity 52b via 60 and 64 from entering the bore 78 and passage 40. This is important in a gasoline station vapor recovery system wherein it is desirable not to have gasoline enter into thevapor ~ .
return line. -`
As stated previously, the diaphragm 54 is subjected -to the pressure differential resulting from the flow of gasoline through the line 38. Such pressure dif-ferential is proportional to the rate of flow of . .
gasoline throught he valve. The area of the diaphragm 54 exposed to pressure in the recess 52b is greater than that o~ diaphragm 84, thus the diaphragm 54 will rise when the pressure below it exceeds that above, relatively independently of the incidental pressure differential between the two faces of diaphragm 84.
The pressure differential created by flow of gasoline thus raises the diaphragm 54 therebylifting the conical portion 82 of the valve element 66 upwardly off the ~ .
valve seat 80, thereby permitting flow of vapor through the passage 40 at a rate which is a direct function of the rate of flow of gasoline through the valve.
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The diaphragm 84 also provides a pressure regu-1~ lating function for -the valve. For example, if the ,~ pressure in the cavity 52b will cause the diaphragm ~ _ 7 -.

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and hence the valve element 66, to tend to move down-wardly, tending to partially close the bore 78, causing the pressure in bore 72 to increase. Likewise, if the pressure in passage 40 increases to a level greater than that in cavity 5s, the valve element will tend to lift off the seat 80 more than dictated by the gasoline .
flow rate to ~`educe the pressure in the passage.

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: - 7a - -32~8 - -Suitable fasteners, not shown, such as nuts and bolts, connect the three parts 42,44 and 46, the diaph- -ragms 54 and 84 into a unitary assembly. Also suitable sealing rings, not shown, may be provided in various parts of the valve housing, such as at the interconne-ction of the bore 60 and passage 64. -While it is not necessary for many applications, preferably a separate pressure regulator, shown schem-atically at 90 in Fig.2, is provided with the valve 18 when the latter is employed in vapor recovery system. -Such regulator maintains the vacuum in the suction -line 26 lar~ enough not to allow too much air to be drawn in from outside the tank which might create an explosive mixture. Any desired form of pressure regu-lator may be utilized. The pressure regulator is preferably upstream of the valve 18 and may be made . . .: ' ' an integral part of the valve.~
While the embodiment disclosed herein utilizes flexible diaphragms as the movable pressure responsive i member, it will be appreciated that the diaphragms may be replaced by slidable pistons sealed with 0-rings if desired. This modification would be particularly useful ! if the valve is to be sub~ected to relat.ively high pressures.
Referring now to Fig. 3, an embodiment of the dé-vice of the invention incorporating integral compensa-tion for gasoline pressure variations will be described.
It will be noted from ~ig.2, that increases in gasoline pressure into the passage 38 can have the effect of biasing the entire valve member 66 down- i ward, even though the differential across diaphragm ~
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~0~3;i~8 54 continues to be governed by the venturi effect generated in 56 as already described. This is true because gasoline pressure variation influences the differential across diaphragm 84, liquid gasoline being in contact with the upper surface of 84 without any counterbalancing fromthe vapor chamber below.

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' " ~'' ' In the embodiment of Fig. 3, all parts which are substantial duplicates of parts shown on Fig. 2 are identified by like numerical legends. The description of such parts set forth in connection with Fig. 2 also applies to Fig. 3.
Basically, Fig. 3 incorporates a third diaphragm 91 separates chambers 93a and 93b formed between a modified housing or body member 44a and an additional housing or body member 90. These members 44a and 90 are joined in the same manner as are 42 and 46, as previously described.
A passage 97 connects chamber 52a to chamber 93b ' : !, . .. ...
Thus liquid gasoline from 52a exerts an upward force on 91 essentially proportional to gasoline pressure, since chamber 93a is directly vented to the atmosphere -through a passage 96.
It should be noted that passage 97 passes through portions of housing members 42, 46, 44a and 90, but does not communicate with any of the chambers or bores, its sole function being to connect chambers 52a and 93b.
The area of diaphragm 91 separating 93a and 93b is substantially the same as for diaphragm 54 within . . . .
the bore below 52b. ~ ;
:: i A connector rod 94 serves to mechanically connect the conical valve member 82 to diaphragm 91 through ~ ;
a spring 95. The said spring 95 serves to permit vari- , ation of the mechanical relationships, although it ~:
could be replaced by a continuation of rod 94 to ~ -obtain a oneOfor-one motion relationship between 82 and 91. Such considerations would be matters of design.
~ _ 9 _ ~09~3Z9~3 A seal 98 prevents leakage between vapor passage 40 and chamber 93a. Leakage at that point is unlikely even with a minimal sealing effort, sich only the dif-ference be-tween the vapor line returning to the suction pump 35 (see Fig. 1) and atmosphere is extant across seal 98.

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Parts 6 8 and 92 serve e s sentially the same purpose s .
In ~rder to explain the operation of the additional structure of ., Fig. 3, the venturi pressure in chanlber 52a will be called Pv~ the vapor lnlet pressure is PA, and PO is atmospheric pressure.
;) The magnitude of PV ~ Po~ which is the upward pressure on 91, .. . . .
will be seen to be always smaller than the magnitude of PV ~ PA~ the;
differential pressure acting on diaphragm 84 when the device is operating, ; The net effective force is Agl (PO - PA) acting downward (in Fig. 3) and tending to restrict the vapor valve oriflce (formed between 80 and 82).
0 Since the effective areas of diaphragms 84 and 91 are substantially equal PV tends to balance out, making the device substantially independent of . . .
gasoline pressure variations. Ag1 is the effective area of diaphragm 91.
The action described tends to afford regulation of the vapor inlet ;~i pressure with variation in suction or vapor exit pressure. An automatic -~'5 trimming operation on the modulating position of the vapor valve due to : . :
modulation of gasoline flow rate is thereby achieved.
Dlaphragm 9I may be of the same gasoline resistant rubber or like material as is used in the other diaphragms 54 and 84. - I
It 19 understood, of course, that thin metallic diaphragms could 1~ be used. Selectlon of materials is a matter of design within the ordinary `1 sklll of the art, suitable materials for all parts being readily selected.
There are no critical material requirer.ants.
Referring now to Figs. 4a and 4b, a third embodiment of the invention will be described. This third embodiment presents cert?in practlcal advan-~,!5 tages vis-a-vis, the other embodiments hereinabove described. By re-arranging the functional sub-assemblies of the overall valve assembly according to the invention, it has been possible, as shown ln Fig. 4b particularly, to oliminate sliding seals and to afford improved regulation in respect to gasoline pressur3, so that potential conditions of lock-down ,, .- 10 ' ' ' ' ' '"

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of the main vapor value due to high gasoline pressure are more effectively avoided, Moreover, the embodiment of Figs. 4a and 4b is less subject ;~ to the influence of the vapor blower pressure variations on the main vapor valve.
;5 In the particular embodiments of Figs. 4a an~ 4b, the construction -~ was such that the li~uid gasoline venturi was somewhat offset physically j from the valve housing components. A housing section lO0 is seen onFig. 4b, representing a centerplane sectional view of the valve functional .,.
parts, whereas Fig. 4a represents a sectional view taken behind that of io Fig. 4b through the centerline of the liquid gasoline vellturi. The exact relationship of these parts is, of course, a matter of design choice, and not a specific aspect of, or limitation on, the present invention, so long as the various passages and relationships which will be described here-lnafter, are provided.
In describipg the additional embodiment of Figs. 4a and 4b, it is to be understood that the same materials, all well known in these arts, ~' are employed. The various housing parts might typically be aluminum alloy (or other non-ferrous alloy) castlngs. Well-known machining and fabrlcating operatlons provlde the bores, threadlng, flat matlng surfaces, etc., as requlred.
` The houslng parts lOOa and 100b may be projectlons on the back of ; ~ the houslng assembly as lllustrated in Fig. 4b, joined to the venturi section body 100, typlcally via screwer bolt 130. In addition to general mechanlcal mounting consideratlons, these latter described parts provide for the ducts 'S or passages 101 and llOj comparable to 58 and 60 in Fig. 2. The part 129 ~i ~ ("snorkel " tube) and is an extension of the passage 110 fnr a purpose to be described hereinafter and is only applicable to the embodlment of Flg. 5 i to be described subsequently herein). ~In Fig. 9a, the passage 110 breaks ;~
'~ ttrough the gasoline venturl wall as a slde bore, comparable to 60 of Fig. 2, !30 without the " snorkel" 12 9 .~

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V432~8 Referring now to FigO 4b in palticular, it will be noted at the outset that no sliding seals are employed. The spindle 106 carries the main vapor seal valve plunger 126 up and down, as illustrated, and .. . .
with it, washers 111 and 112, bushing 115, washers 107 and 108, bushing 114, washers 104 and 105 a~d spring retaining washer 136. These move-` ments produce flexure of diaphragms 103, 109 and 113 contemporaneously and in the same directional sense. The seals evident along the inside diameters of bushings 114 and 115 are fixed seals intended only to prevent inter-chamber leakage. ;
` 10 The valve housing comprises essentially three parts, namely, 127, 114 and 128. These sections are held together via conventional methods with entirely conventlonal sealing techniques app~ied. The section 114 l comprises the lLquid- gasoline pressure compensator. The aforementioned i spindle 106 and all the parts mechanically~ fixed thereto, which translate .. ~ , . .: .
up and down ~as viewed in Fig. 4b) and do not rely on sliding seals or other sllding frlction tçchnitl~les to maintain their lateral ali~nment. Actually it will be apparent that the diaphragms 103, 109 and 113 easily afford ; l sufficlent lateral rigidity to maintaln alignment of the spindle and related parts.
A valve seat 125 operatlng in cooperation with the main vapor valve plunger 126 is capabie of metering the vapor flow from the vapor inlet and the outlet to the way to pump 35 interrupting it completely when the plunger j ls In the extreme downward positlon, as lllustrated~ Conversely, a varlable flow of vapor through the main vapor passage in 128 irom vapor '~ 25 lnlet to vapor outlet is produced in accordance with the amount by which .,. ,~ .
the plunger 126 is lifted during operation from the seat 125.
It will be noted that the interior cavities of the valve above the ;, i , .
plunger 125 compri~e a lower cavity 135 which is in communication with the vapor lnlet; a chamber 134 constrained between diaphragms 109 and 113;

3 a chamber includLng both I32 and 133 constrained between dLaphragms 103 ;

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The said upper h~using member 127 downthard facing concavity overlaps the member 114 producing a small annular extremity 137 as part of the S cavity 131. The reason for this will be apparent hereinafter in connection with the description of Fig. 5.
Actually this annular cavity extension 137 serves no specific purpose in connection with the functioning of Fig. 4b, but is provided in order to allow for converslon of the embodiment of Fig. 4b to that of Fig. 5 merely by partial disassembly, removal of certain parts and reassembly without modifLcation or rework of any parts.
The housing part 127, together with the plug 123 emplaced in the top of 127, serve together as a bonnet for the assembly.
- -It will be noted that a threaded insert sleeve part 118 is fitted within a contral internal bore in the upper end of 127 and seated therein `1 by means of a .hread engagamen. 119. Part il8 is sealad ~,-ia saal 41 against the internal bore of the aforementioned part 127. An internal .~, , .
,, shoulder on part 118 applies a compression bias on spring 116 tending to ' ~1 .
; ~ blas the spindle 106 downward (in the direction of closùre of the 125/126 valve/seat arrangement). The amount of thls spring bias may be adjusted ln accordance wlth the extent of the thread engagement at 119. Part 118 ~' will be seen to have its own lnternal bore above the sald internal shoulder ~ ~
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bearing on sprlng 116, this addltional bore accommodating a threaded plug - ~
120. The threaded plug 120 provides an additional ad~ustment of the ~ ~ -resillent bias on the splndle 106 by méans of sprlng 117 retained against ~ ;
the top of spindle 106 and a pro~ection on the bottom of threaded plug 120.
; ' -1 The extent of thls compression bias may be adjusted by rotating the said ;~ ~ threaded plug 120 and consequently the extent of the thread engagement 121.
~ ~ A screwdriver slot 122 is lllustrated in thls connection. Plnally, the cap t ~;30 plug 123 seats in a counter bore and threaded upper portion of part 127, ; ~; ~

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~ .~J43Z18 th~ ~hreaded engagement being identified as 124; and the corresponding seal is 142.
A boss 138, forming a part of the bonnet casting 127, has a central bore 139 in communication with the passage 102, and is sealed by means ` 5 of a threaded cap 140, preferably with the usual resilient O ring seal. The ,. . . . .
external communication with the passage 102 thereby afforded permits the attachment oi a manometer or ottler instrument for the purpose of operation-ally adjusting the device specifically by rotation of threaded plug 120.
; The passage 102 assumes essentially the vapor inlet pressure I condition extant in the valve at any time, and this is an independent parameter of significance in connection with adjustment of the device.
Concerning operation of the device, it will be noted that the pressure dlfferential across diaphragm 109 is substantially only the true algebraic dlfference between the passage 101 and 110 pressures, l.e, it is a lS function only of the gasoline delivery rate through 100.
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,' Gasoline iAput presstlre variations are effectively balanced outaoross 109, and slnce the under side of diaphragm 103 and the upper side ' of 113 present the same area to the gasoline pressure, there is inherent `~ `l cancellatlon o~ net forces due to liquld gasoline pressure changes.
Stlll further, lt will be noted that passage 102 serves to equalize the vapor pressure between chambers 131 and 135 (top of diaphragm 103 and bottom of dlaphragm 113~ thus also provlding inherent balancing out of force dlfferentlals resultlng from vapOr blower net pressure - as, for example, caused by varlatlon in the number of gasollne pumps operating irl parallel c)n the system at any time.
`~ Referring now to Fig. 5, a simplified "on-off" version of the device ls deplcted. Here the regulator section 114 is omitted and the bonnet casting 127 Is~ fitted onto 128. The annular chamber portion 137 disappears because the effective bores of 127 and 128 match.
A shorter spindle 106 is employed and the components above ~04 in 14- ;~
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Flg. 1 are now adjacent to 107. Passage 102 is omitted by sealing or plugging the casting openings.
. r. In Fig. 5, it is assumed that the vapor return pump 35 suction is relatively high, or that the gasoline delivery nozzle 22 is tightly fitted into the automobile tank filler pipe (as by a gasket or resilient coliar). In that gas, displacement of vapor in the automobile tank during filling drives the vapor back to the reservoir 12 without need for pump 35.
The snorkel 129 may now be seen to provide some fluid ram effect augmenting the pressure in chamber 131. The result is a maximum up move-` 10 ment of 106 and consequently, a maximum openin~ of the 126/125 valve opening.
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Removal of the regulator section, as aforementioned, removes the liquid - gasoline venturi connection and consequently no regulation of vapor return flow as a function of valve 126/125 opening is effected. The chamber 1~1 is preferablY closed to avoid external gasoline or vapor leakage in the event of a failure of diaphragm 109.
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Obviously, the embodiments of Figs. 4 and 5 could be constructed with sliding piston arrangements in lieu of the de1ecting diaphragms, however, :1 .
the diaphragms are simple, relatively inexpensive and free of surface sliding friction problems. ~ `
Although the present invention is consldered particularly useful in retall gasoline vending, it is also obviously applicable to the vending of other liquld hydrocarbon fuels whicb are relatively volatile and thereby vapor-Ize and produce air pollution if the vapors are allowed to pass into the atmosphere, Variations and modificatlons within the scope of the invention, once its princlples are understood, are of course possible. Accordingly, it is not :; . ,.. ,. i,~
i ~ ` intended that the specific embodiments shown should be regarded as deining .1 the scope of the inventlon, the drawings and descrlption being intended as I ~ illustrative only. Pistons may be substltuted for one or more or all of the , ~ - ~ - :
~, 30 - diaphragms disclosed herein, although one or more diaphragms may be used ~ ;
in combination with one or rnore plstons.
~ 1~` ; WTO:dr ; `; August 1, 1974 .. : : - . .

Claims (8)

WHAT IS CLAIMED IS:

1. A flow control valve for maintaining the fluid flow rate in a first line proportional to the fluid flow rate in a second line comprising:
a valve housing having first and second passages there-through, said first passage being adapted to be coupled to said first line and said second passage being adapted to be coupled to said second line;
a restriction in said second passage for producing a pressure differential proportional to the rate of flow of fluid passing through said second line;
a first cavity in said housing divided into first and second sections by a movable member;
first means providing flow communication between said first cavity section and said restriction;
second means providing flow communication between said second cavity section and an unrestricted portion of said second passage whereby said movable member is subjected to said pressure differential;
a valve seat formed in said first passage; and a valve element in said second cavity section fixed to said movable member and positioned to close said valve seat, said valve element shifting away from said valve seat in response to said pressure differential whereby the rate of flow of fluid passing through said first line will be a predetermined function of the rate of flow of fluid passing through said second line.

2. A valve as set forth in Claim 1 including:
means biasing said valve element against said valve seat to normally prevent flow of fluid through said first passage.

3. A valve as set forth in Claim 2 wherein:
said biasing means comprises a spring in said first cavity section bearing against said movable member.

4. A valve as set forth in Claim 1 including:
a second movable member between said second cavity section and said valve seat;
said valve element being sealed to said second movable member; and the exposed area of said second movable member being less than that of said first-mentioned member.

5. A valve as set forth in Claim 1 wherein:
said cavity has a cylindrical configuration;
said movable member extends across said cylindrical cavity generally perpendicular to the axis thereof;
said valve element and valve seat are coaxially positioned with respect to said axis;
a bore is provided in said housing extending between said second cavity section and said first passage coaxial with said axis;
a second movable member is provided in said housing extending across said bore between said valve seat and said cavity, the exposed area of said second movable member being less than that of said first-mentioned movable member; and said valve element is sealed to said second movable member.

6. Apparatus according to Claim 1 comprising;
a second cavity spaced with respect to said first cavity;
a third movable element arranged to divide said second cavity into third and fourth separate sections;
means connecting said third cavity section to the atmosphere;
means providing flow communication between said first cavity section and said fourth cavity section;
and a mechanical connection between said third movable element and said valve element, thereby to provide automatic trimming of the modulating position of said valve element as a function of gasoline pressure variations.

7. Apparatus according to Claim 6 in which said third movable element extends across said second cavity generally perpendicular to the axis thereof and said mechanical connection comprises a series rod and spring joined to the center area of said third movable element and said valve element.

8. Apparatus according to Claim 6 in which said third movable member extends across said second cavity in a plane generally perpen-dicular to the axis of said second cavity, and said mechanical connection comprises at least an elongated member attached on one end to the center area of said third movable member and passing through said third cavity section, through an opening in said housing and into said valve seat substantially coaxially with and attached said valve element.