GB2131917A - Solenoid-operated valves - Google Patents

Abstract

The valve comprises a body 1 with a portion 2 forming a gas flow passage 3, a portion 4, a valve cover 7 for closing off the end 8 of the passage 3 and a solenoid 9 for moving the valve cover 7 away from the end 8 of the passage 3. The valve cover 7 comprises a disc- shaped shoe 22 and an armature support 23 between which is clamped a flexible stainless steel diaphragm 24 which is itself clamped between an annular clamping ring 34 and the uppermost part 31 of the valve portion 4. The valve shoe 22 forms a seal with the end 8 of the passage 3 by engaging a rubber "O" ring 20 located in a recess 19 in the upper face 18 of the portion 2. <IMAGE>

Description

SPECIFICATION A valve for controlling fluid flow The present invention relates to a valve for controll ing fluid flow.

According to the present invention there is provided a valve for controlling fluid flow, the valve comprising a bodywith a portion forming a central passage for conveying fluid through the valve, a coverwhich is linearly movable relative to the passage between positions where the passage is open orclosed at one end bythe cover and means forforming a flexible seal between the cover and that portion of the body surrounding the closable end of the passage.

Embodiments ofthe invention will now be particu larly described with reference to the accompanying drawings in which: Figure lisa side view in section of one embodiment ofthe valve arranged for normally closed operation, Figure 2 is a view along lines Il-Il of Figure 1.

Figure 3 is a simplecircuitforenergisingthe solenoid part ofthevalve for ONIOFF or HIGH/LOW operation, Figure 4 is a side view in section of another embodimentofthe valve, Figure 5 is a schematic view of the valve shown in Figure 4 when functioning in one mode, and Figure 6 is a schematic view of the valve shown in Figure 4when functioning in another mode.

Referring to Figures 1 and 2 thevalve comprises a body 1 with a fist or inner portion 2forming a passage 3 to receive and discharge fluid, a second or outer portion 4forming a chamber 5 with the portion 2, a threaded port 6 in the portion 4, a valve cover 7 for closing offthe end 8 ofthe passage 3 and means, in the form ofan electric solenoid 9, for moving the valve cover 7 away from the end 8 ofthe passage 3.

The portion 2 comprises a generallytubular central part 1 0formed with an internal passage 3. The bore 3 has internallythreaded lowermost end 11 opposite the uppermostend8.The portion 2 isformed atits lowermost end with a flanged disc 12 to form a seat for the portion 4. The disc 12 has a circular recess 13 formed in its uppermost face 14to receive a seal 15 in the form of a nitrile rubber"O" ring to form a seal with the portion 4 as will subsequently be described.

The tubular central part 10 ofthe portion 2 is formed with an upwardlyflared part 16terminating in an upper end 17 in which the bore end 8 is formed and which is of a greater external diameterthan the remainder ofthetubular part 10. The upper end 17 of thetubularpartl0isformedwith an annularendface 18 which is provided with an annular recess 19 circumscribing the end 8 ofthe bore 3. Avalve cover sealing means intheform of a nitrile rubber"O" ring 20 locates in the recess 19 with part of its surface projecting above the end face 18 so as, in use, to be engageable bythe valve cover 7.

Asanoptional feaure, the wall of the tubular part 10 may be provided with a port 21 to provide a further connection to the chamber 5 forfluidflowing in the bore 3 for reasons which will be mentioned subse quently. The valve cover 7 comprises a generally disc shaped valve shoe 22 for engaging the ring 20 and a support member 23 fixed to the shoe 22 and also secured to the solenoid 9. Clamped between the shoe 22 and the support member 23 is an annular diaphragm 24 of stainless steel. Extending through a central aperture in the diaphragm 24 is a clamping screw 25 which is received in a corresponding countersunkthroughgoing clearance bore in the shoe 22 and a blind hole in the support member 23. As will be seen an innermost annular portion of the diaphragm 24 is held between the shoe 22 and the support member 23.

The outer portion 4 has a generally cylindrical shape which is generally concentric with the tubular part 10 ofthe portion 2 and is dimensioned to form a generally annular chamber 5 therewith. An intermediate part 26 of the portion 4 is provided with a port 6.

The portion 4 is formed at its lowermost end with a narrowed annular neck portion 27 to engagewith the seal 15 located in the disc 12 of the portion 2. The annularflange 28Ofthedisc 12 is received as a close fit in the recess formed between the neck 27 and the main body 29 of the portion 4.

The dise 12 therefore forms with the portion 4 and the "0" ring 15 a sealed lower end to the chamber 5.

The main body 29 ofthe portion 4 is formed with an upwardlyflared end 30 terminating in an annular end face 31. The end face 31 is provided with a concentric annular recess 32 in which is disposed a seal 33 in the form of nitrile rubber "0" ring. A clamping ring 34 is screw clamped to the end face 31 by means of eight countersunk clamping screws 35 (only two shown).

These screws 35 extend through corresponding countersunkthrough-going clearance bores in the clamping ring 34 and into corresponding blind tapped holes in the end 30 of the outer portion 4.

The screws 35 are as shown located at a greater radius then the seal 33 which projects slightly above the recess 32 to enable the clamping ring 34to form a seal with the ring 33. As will be seen an outermost annular portion ofthe diaphragm 24 is also clamped between the "0" ring 33 and the clamping ring 34. The diaphragm 24 and valve shoe 22 therefore form with the clamping ring 34, "0" ring 33 and the portion 4, a sealed upper end to the chamber 5 which is thus sealed to atmosphere save forthe port 6. As shown in Figure 1 the valve shoe 22 is a radial close fit within the aperture formed in the uppermost end 30 ofthe portion 4.

The solenoid 9 comprises a movable armature 36, a core 37 and a pair offixed wire-wound coils 38. The armature 36 and the core 37 are generally "E" shaped and are constructed of a suitable grain oriented magnetic steel such as Alphasil 30M5. The limbs 39, 40 and 41 of the armature 36 are separated from the limbs 42,4344 of the core 37 by a distance which is sufficient when the armature 36 is attracted towards the core 37 to cause the valve shoe 22to move away from the "0" ring 20 and breakthe seal therewith. The coils 38 are of varnished copperwirewoundon a cardboard former. Each coil 38 is mounted on the outer limbs 42 and 44 of the core 37 and connected in parallel electrically.

As shown in Figure 2 a pair of brackets 45 and46 is provided to anchorthe solenoid core 37 to the clamping ring 34. Each bracket 45 and 46 comprises an uppermost vertical portion 47 which is secured to the core 37. The portions 47 of each bracket 45 and 46 are located on opposite faces of the core 37 and are secured together and to the core 37 by two connecting pins 48 and 49 extending through the portions 47 and the core 37 itself. The brackets 45 and 46 also each comprise a lowermost horizontal flange portion 50 which is clampedtothe clamped ring 34bycounter- sunk screws 51 and 52 extending into threaded bores in the clamping ring 34.

The brackets 45 and 46 also comprise intermediate horizontal and vertical portions 53 and 54 respectively connected to the uppermost and lowermost portions 47 and 50 respectively.

Mounted between the armature 36 and the coils 38 is a steel closure spring 55. The ends of the spring 55 engage with a pair of brass retaining cups 56 and 57, the upper cup 56 abutting with the intermediate horizontal portions 53 of the brackets 45 and 46 while the lowermost cup 57 abuts with the inner surface of the body 58 (see Figure 1 of the armature36whitethe spring 55 itself circumscribes the central limbs 40 and 43 ofthe armature 36 and core 37 respectively. In use, the spring 55 urges the armature 36 and the support member 23 downwardly to cause the shoe 22 to engage the "0" ring 20 and close the endS of the tubular central part 10 inthevalve portion 2.

The member 23 is formed with a pair of ears or lugs 59 and 60 one at either side of its uppermost end.

These lugs 59 and 60 are connected to the armature 36 (to connect the member 23 and thereby the shoe 22 to the armature 36) and to each other by means of a connecting pin 61 extending through the lugs 59 and 60 and the armature body 58.

To open the valve against the pressure of the spring 55, the wire wound coils 38 are energized to magnetisethe core 37 and cause itto attract the armature 36 to the core. The armature 36 moves some or all of the small distance between its limbs andthose of the core 37. Movement of the armature 36 causes the support 23 and shoe 22 also to move upwardly towards the core 37 thereby flexing the diaphragm 24. Upward movement of the shoe 22 causes itto breaktheseal formed by the shoe 22 and the ring 20 and subsequentlyto open the passage 3.

When the coils 38 are de-energised the spring 55 causes the armature 36 and valve shoe 22to move downwardly so thatthe shoe 22 intimately engages the ring 20 and once again seals offthe end 8 ofthe bore 3.

In general the passage end 11 serves an inletto receive fluid under pressure and the port 6 serves as an outlet to discharge the fluid entering the chamber 5. In this case the fluid enters the chamber 5 from the bore 3via the upper end 8 ofthe passage 3 afterthe shoe 22 is moved sufficientlyto open the passage end 8. the port 21 is provided in the tubular part 10, fluid continues to flow from the passage 3 to the chamber 5 and outthrough the outlet port 6 even when the valve is closed, thus providing a pilotfluid supply. In this case the bore 21 enables the valve to operate in a HIGH/LOW mode ratherthan, in the absence ofthe port 21, in an ON/OFF mode.

Alternatively, where circumstances dictate, fluid can be caused to flow inthe opposite direction by connecting the fluid supplytothe port6whichthereby serves as an inlet, with the passage end 11 serving as an outlet In this case, fluid entering the chamber 5 flows into the passage 3 by way ofthe open valve and out by way of the end 1 1.The port 21, if provided, will continueto allowfluidtoflowfromthe chamber 5 into the passage 3 even when the valve is closed.

By suitable selection of the materials from which the valve and electromagnetic components are made and ofthe dimensions of the components, the valve can be used as a low power fluid control valve with an ON-state current requirement low enough to allow operation from a miniature cell, for instance, a nickel-cadmium rechargeable cell. Indeed it is possible to provide a valve which in the ON-state consumes a current of less than 125mAat 1.0 volt Inthisform a small low-powercell, preferably ofthe rechargeable type and preferably kept "topped-up" normally by trickle-charging fromthe mains, can supply power to operate the valve, in the event of an extended failure of the mains electricity supply.Where this feature is advantageous (eg. in association with low-power microelectronic control circuitry) the applicant's valve constitutes an ideal substitute for the conventional solenoid valve, which cannot be operated for an extended period from a compact, low-power source.

Referring to Figure3 a simple circuit is shown for operating the valve in an ON/OFF or HIGH/LOW mode.

The circuit comprises a pair of resistors R1, R2, a capacitor C in series with the resistor R2 and the solenoid 9 in parallel via the switch S with R2 and C but in series with R1. The circuit derives its power from a low voltage (1.2v) source such as a rechargeable nickel-cadmium cell NC.

In this case, during normal operation with electrical power being suppliedfromthe mains,thenickel- cadmium cell NC is trickle-charged by means of a conventional transformer/rectifier circuit (not shown).

Should the supply of mains electricityfail, energy to operatethevalve is withdrawn when required from the cell NC. With the switch S open, the valve is electrically in the "OFF" state. Capacitor C is charged up by the cell NC. When the switch S is closed either manually or under the control of a microprocessor, capacitor C dischargesthrough R2 to provide a high current impulse to energise the solenoid 9to operate the valve. As the capacitor C discharges the solenoid current drops and therefore the power consumption also drops ultimatelytothe normal low operating level necessaryto hold the valve in operation. This low operating current is supplied directly from the cell NC via resistor Ri, as long as the switch S remains closed.

It will be appreciated that more sophisticated circuitry can be provided to control the solenoid and thevalve. For instance, by regulating the solenoid current it would be possible to operate the valve in a "modulating" modewheretheflowrateoffluid through the valve could be controlled bythe extent by which the valve opens in dependence upon varying operating parameters such as temperature, pressure, the composition of a fluid mixture, etc.

Referring to Figure 4, the valve comprises a body 101 with afirstorinnerportion 102 forming a passage 103 to receive and discharge fluid, a second or outer portion 104forming a chamber 105 with the portion 102, the portion 104 having a threaded port 106 and a fluid flow passage 107 communicating with the chamber 105, a valve cover 108 for closing off either the uppermost end 109 ofthe passage 103 or the lowermost end 110 of passage 107 and means, in the form of an electric solenoid 111, for moving the valve cover 108 away from the end 109 of the passage 103.

The portion 102 is very similarto the portion 2 of Figures 1 and 2 and has a tubular central part 112 formed with the internal passage 3, the passage 3 having an internally threaded end 113 opposite the uppermost end 109. The portion 102 has a flanged disc 114forming a seatforthe portion 104,the disc 114 having an annular recess to locate a nitrile rubber"O" ring seal 11 Swith which the portion 104forms a seal.

The tubular central part 112 has an upwardly flared part 1 16 terminating in an upper end 117 in which the bore end 109 is formed. The upper end 117 ofthe tubular part 112 is formed with an annular end face 118which is provided with an annular recess 119 circumscribing the end 109 of the bore 103. Avalve cover sealing means in the form of nitrile rubber "0" ring 120 is located in the recess 119 with part of its surface projecting above the end face 1 18so as, in use, to be engageable bythe valve cover 108.

The portion 104 is generally cylindrical and forms a generally annular chamber 105 with the portion 102.

An intermediate part ofthe portion 104 is provided with the internallythreaded port 106 while a lower part has a narrowed annular neck 121 to engage with the seal 115 when the flanged disc 114 is received in the recess formed between the neck 121 and the main body 122 ofthe portion 104.

The main body 122 of the portion 104 is formed with an upwardly flared end 123 which is provided with the fluid flow passage 107 which communicates with the chamber 105. The passage 107 comprises a first part 124 extending inwardlyfrom the outer wall of the portion 104 and a second part 125 formed as a vertical bore which communicates with the annular chamber 105. The first part 124 is partially internallythreaded at a position adjacent to the outerwall of the portion 104.

A circular recess 126 isformed in the uppermost face 127 of the portion 104. This is itself provided with an annular recess to receive a nitrile rubber "0" ring 128 which is dimensioned to project above the level of the face ofthe recess 126. The recess 126 and the second passage part 125 communicate byway of a central bore 129 through which, in use, the stem 130 of the valve cover 108 slideably and sealingly extends.

The valve cover 108 comprises a disc-shaped valve shoe 131 from which the valve stem 130 upwardly extends. The shoe 131 has a planar lowerface 132 which, in use, engages with the "0" ring 120 in one lowermost position to close and seal off the upper end 109 ofthe bore 103. The shoe 131 also has an upper face 133 which is provided with an annular recess to receive an "0" ring 134which isdimensionedto project above the level of the face 133 so that, in use, in an uppermost position the shoe 131 forms a seal with the surface surrounding the bore 125 to close offthe bore 125. The arrangement is such that when the shoe 131 seals offthe end 109 of the bore 103, the passage 107 is open to the chamber 105 while when the shoe 131 seals offthe end 110 ofthe bore 125 the passage 103 is open to the chamber 105.However, the shoe 131 can be moved to an intermediate position between the bores 103 and 125 where the seals are both broken and the bores 103 and 125 simultaneously open to the chamber 105.

The valve stem 130 is connected at its uppermost end to the movable armature 135 of a solenoid (not shown) which is of similar construction and operation to that previously described in relation to the valve of Figures 1 and 2. The stem 130 has spaced ears 136 like the support member 23 of the previously described valve and these ears 136 are connected to the armature 135 via a connecting pin 137 in a similar manner.

The stem 130 comprises uppermost and lowermost portions 138 and 139 respectively, the uppermost portion 138 incorporating the ears 136.

Astainlesssteelannulardiaphragm 140 is clamped centrally between both the uppermost and lowermost portions 138 and 139 ofthe valve stem 130 and peripherally between the outermost portion 104 andaclampingring 141.A clamping screw 142 extendsthrough athreaded bore in portion 1 38 of the valve stem 130 and the central aperture 143 in the diaphragm 140 and terminates in a threaded blind hole in portion 138 ofthe valve stem 130. In use, the diaphragm 140 rests on and compresses the sealing ring 128 under a compressive force exerted by the clamping ring 141. The diaphragm 140 thereby seals the upper end of bore 125.

The clamping ring 141 is provided with a peripheral flange 144 which is screw clamped to a peripheral annular ridge 145 on the upper face 127 of the portion 104 by means of eightcircumferentallyspaced coun tersunkscrews 146 (only two shown) which extend into suitably threaded blind holes inthe ridge 145. The clamping ring 141 has a neck portion 147 located within the recess 126 in the uppermostface 127 of the outer portion 104, the neck portion 147 engaging with the diaphragm 140.

The clamping screw 142 also clamps a leaf spring 148 to a stepped portion on the uppermost portion 138 of the valve stem 130. The ends of the leaf spring 148 are secured by screws 149 to the internal periphery of the clamping ring 141.The spring 148 tends to bias the valve 108 downwardly so thatthe va Ive shoe 131 engages the seal 120 so as to close offthe passage 103 and fully open the passage 107. The valve shoe 131 can be lifted by the armature 135 against the spring bias when the armature 135 is attracted towards the core (not shown) after the solenoid coils (not shown) have been energised. Eventually, if lifted far enough, the "0" ring 134 will engage the surface surrounding the bore 125to close offthe passage 107 and fully open the passage 103.

Referring to Figure 5, in this example of valve operation, port 106 serves as an inletforfluid to the valve "V" while the passage 103 and 107 serve as outlets for the fluid. In this case the valve could be operated in the mannerofaflowdiverterwith fluid flow being diverted into eitherthe passage 103 or the passage 107 depending on the position of the valve shoe. The circuit shown in Figure 3 would provide the required solenoid control to enable such an operation to be performed. Alternatively the use of a more sophisticated "modulating" circuit (as previously mentioned) would enable the valve to be operated as a flow proportioning type device.In this case in response to a variable current provided by the control circuit the valve shoe could be positioned between the ends 109 and 1 ofthe passages 103 and 107 respectively as to enable fluid to enter both the passage 103 and the passage 107 at rates dependent onthe position ofthe shoe 131 relative to the ends of the passage 103 and the passage 107. The wall of either or both ofthe passages 103 and 107 adjacentto the chamber 105 can be provided with by-pass ports 150 and 151 (see Figure 4) similarto port 21 in the valve of Figures 1 and 2to cause the valve to operate in a HIGH/LOW proportioning mode with fluid still able to enter one or either of the passages (as the case may be) at a low rate when the main flow has been shut off by the shoe. The by-pass flow is shown schematically bythe broken lines in Figure 5.

Referring to Figure 6, in this example of valve operation, the port 106 serves as a common outlet while the passages 103 and 107 serves as dual inlets.

In this case the valve "V" could be operated in the manner of a fluid flow selector with the appropriate fluid inlet being selected when it is open to the chamber 1 while the other is closed bythevalve shoe. Here again the circuit shown in Figure 3 can be used to provide this type of control function. Alternativelythe use of a more sophisticated "modulating" circuitwould enable the valve to be operated as a mixing device. In this case the valve shoe could be positioned between the ends of the passages 103 and 107 to enable fluid from both inlets to enterthe chamber 105 for mixing.The relative proportion of the fluid ingredientswoulddepend on the relative position ofthe shoe, which position itselfcouldofcourse be continuously varied in dependence on signals from external sensors serving the control circuit.

In this case, should the valve contain any by-pass port(s) similartothose previously described, the valve would operate in a HIGH/LOW mixing mode, with fluid still able to enterthe chamber at a low rate from one or either (as the casemay be) of the passages 103 and 107, when the corresponding main flow has been shut off by the valve shoe. Again the bypass flow is shown schematically in broken line.

Itwill be appreciated thatintheforegoing variants ofthe applicant's valve: (i) The valve can alternatively be operated by an actuator comprising afixed armature and a moving core/coil assembly.

(ii) The valve can alternatively be operated by an actuator of a type other than electromagnetic, for example, pneumatic, hydraulic, magnetic, bimetallic, thermoexpansive, magnetostrictive, piezoelectric, etc.

(iii) Changes in the relative positions of valve shoe and passage end(s) can be accomplished either as described, or alternatively by movement of the passage end(s),the valve shoe remaining immobile, or again by any appropriate combination of movements of the valve shoe and passage end(s) jointly.

(iv) The biassing force to oppose the primary actuatorforce can be provided by gravity, with or without the assistance of a spring.

(v) Asingle circuit can be used to provide the two-state or infinitely-variable control actions described.

(vi) The valve can be used to control the flow both of gases and of liquids.

Itwill further be appreciated that the applicant's valve may embody any appropriate selection ofthe features described.

Claims (8)

1. Avalvefor controlling fluidflow, thevalve comprising a body with a portion forming a central passagefor conveying fluid through the valve, a cover which is linearly movable relative to the passage between positions where the passage is open or closed at one end bythe cover and meansforforming aflexible seal between the cover and that portion of the body surrounding the closable end of the passage.

2. Avalve as claimed in claim 1 in which the body forms a further passageforfluidflowthrough the valve independently of the central passage, the cover being linearly movable relative to the further passage between positions where the passage is open or closed at one end by the cover and means being provided for forming a flexible seal between the cover and that portion of the bodysurroundingtheclosable end ofthefurtherpassage.

3. Avalve as claimed in claim 1 in which the body forms a chamber with which the central passage communicates by way of its closable end, the body having an external port leading to the chamber.

4. Avalve as claimed in claim 2 in which the body forms a chamber with which both passages communicate by way of their closable ends, the body having an external port leading to the chamber.

5. Avalve as claimed in claim 3 or claim 4 in which the central passage communicates with the chamber by way of a port having a smaller area than the passage.

6. Avalve as claimed in claim 4 in which thefurther passage communicates with the chamber byway of a port having a smaller area than the further passage.

7. Avalve as claimed in any ofthe preceding claims in which the cover is mounted on the body so asto be movable relative to the body.

8. Avalve substantially as hereinbefore described with reference to Figures 1 to 3 or Figures 4to 6.