US3602097A

US3602097A - Fluid-operated valve assemblies

Info

Publication number: US3602097A
Application number: US809085A
Authority: US
Inventors: Dennis Stephen Dowdall
Original assignee: Telektron Ltd
Current assignee: Telektron Ltd
Priority date: 1968-03-26
Filing date: 1969-03-21
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31
Also published as: FR1599404A; NL6904477A; DE1914690B2; NL142228B; DE1914690A1; JPS4835970B1

Abstract

A fluid-operated valve assembly of the present invention comprises a thrust diaphragm (14) adapted for connection to a driven member and peripherally held at one end of the valve housing. This diaphragm is biased towards a rear position by a bias member (17) from which position it is movable forward under pressure exerted by fluid introduced into the housing to a first position at which mechanical contact is made between the thrust diaphragm and a rear valve part (7). This rear valve part carries an inlet valve member (2A) which is moved forward with the valve part to separate a fluid-inlet port (28) from the thrust diaphragm and mechanical contact is made between the rear valve part and a central valve part (2A, 24A). Further forward movement of the thrust diaphragm moves the central valve part forward to open an outlet valve (23B, 13B) so that fluid under pressure is lost from the housing through an outlet port (29) and then the thrust diaphragm is moved rearward by the bias member to move the rear part rearwards to open the inlet valve and close the outlet valve. The central valve part and the rear valve part are both biased rearwardly by bias members (21, 25). The assembly is capable of automatic reciprocation when fluid pressure is applied and is of application to supply fluid pressure to a fluidoperated motor.

Description

United States Patent [72] Inventor Dennis Stephen Dowdall Primary Examiner-1Paul E. Maslousk y Morden, Surrey, England Attorney-Norman S. Blodgett [21] App]. No. 809,085 [22] Filed Mar. 21, 1969 [45] patented Aug 31, 971 ABSTRACT: A fluid-operated valve assembly of the present [73] Assighee Telektl-on Limited invention comprises a thrust diaphragm (14) adapted for conw Molesey surrey England nection to a driven member and peripherally held at one end 2 priority Man 2 19 Och 3 9 of the valve housing. This diaphragm is biased towards a rear [33 1 Great Britain position by a bias member (117) from which position it is 31 524 6 and 51523 movable forward under pressure exerted by fluid introduced into the housing to a first position at which mechanical contact is made between the thrust diaphragm and a rear valve M'UIDJWEATE VALVE ASSEMBLIES part (7). This rear valve pan carries an inlet valve member 9 Claims. 2 Dnwlng F1gs 21h which 18 moved forward with the valve part to separate a fluid-inlet port (20) from the thrust diaphragm and mechani- [521 US. Cl 911/267, ca] Contact is made between the rear valve part and a central 91/273 91/342 valve part (2A, 24A). Further forward movement of the thrust [51] Int. Cl F01] 15/14, diaphragm moves the centra] valve part f d to open an F01l23/00 outlet valve (23B, 1313) so that fluid under pressure is lost [50] Field of Search 91/267, f the housing through an Outlet pol-t 29 and the the 272, 341 thrust diaphragm is moved rearward by the bias member to References Cited move the rear part rearwards to open the inlet valve and close the outlet valve. The central valve part and the rear valve part UNITED STATES PATENTS are both biased rearwardly by bias members (21, 25). The as- 1,067,613 7/1913 Lane 91/273 sembly is capable of automatic reciprocation when fluid pres 2,603,191 7/1952 Sterrett 91/272 sure is applied and is of application to supply fluid pressure to 3,305,953 2/1967 Mehren et al 91/267 a fluid-operated motor.

23 24A 2A 24 2 I9 -t PATE NTED A1193] IS?! I 3502097 SHEET 1 BF 2 Ha. I.

INVENT OR Dennis .Sfeph en Dawdal/ "(fl mm 3. 5

ATTORNE PATENTEI] AUGBI l9?! 3,602,097

SHEET 2 or 2 INVENTOR enn'ils Sfephen Dowda/l 70mm 8. 1B

, ATTORNE FLUlD-OPERATED VALVE ASSEMBLIES CROSS REFERENCE TO RELATED APPLICATIONS Applicant claims priority under 35 U.S.C. 119 for Applications 14524168 and 51523/68 tiled in the Patent Office of the United Kingdom on Mar. 26, 1968 and Oct. 30, 1968,

This invention relates to fluid-operated valve assemblies, which are capable of providing reciprocation when fluid pressure is applied, and are utilized in fluid-operated motors. In motors of this type a flexible diaphragm is moved between two positions under fluid pressure applied to one face of the diaphragm and the movement of the diaphragm is utilized to move a driven member. This driven member may be a shaft having a ratchet wheel which is driven by a pawl connected to the moving part of the diaphragm. Thus, if fluid pressure is applied intermittently to the diaphragm, which is peripherally held, the center part of the diaphragm will be given a reciprocating movement which is transferred to the driven member.

The present invention provides a fluid-operated valve assembly which operates so that a substantially constant fluid pressure applied to a fluid-driven motor will be converted into an intermittent pressure supplied to the diaphragm by operation of the valve assembly with its snapover action. Thus the diaphragm can be reciprocated with a substantially constant applied fluid pressure.

A fluid-operated valve assembly according to the invention includes a thrust diaphragm, adapted for connecting to a driven member, peripherally held atone end of a valve housing and biased towards a rear position by a bias member from i which position it is movable forward, under pressure exerted by fluid introduced into the housing, to a first position at which mechanical contact is established between the thrust diaphragm and a rearwardly biased, diaphragm-supported rear valve part carrying an inlet valve member so that the inlet valve member is moved forward to separate a fluid'inlet port from the thrust diaphragm and mechanical contact is established between the rear valve part and a rearwardly biased, diaphragm-supported central valve part, and further forward movement of the thrust diaphragm moves the central valve part forward to open an outlet valve so that fluid under pressure is lost from the valve housing through an outlet port and then the thrust diaphragm is moved rearwardly by the bias member to move the rear part rearwardly to open the inlet valve, and close the outlet valve.

The valve assembly of the invention allows a rapid rate of reciprocation to be obtained from a motor diaphragm by the valve assembly having low inertial resistance to high speed movement.

The central. and rear valve parts may be rearwardly biased by bias members between each of them and the thrust diaphragm and the central valve part may be biased from both the thrust diaphragm and rear valve part.

A particular feature of the invention is the support of the moving parts of the valve performed by flexible diaphragms peripherally held in the valve housing. Thus the assembly has no relatively moving parts which are in sliding relationship. Thus the energy losses are low and the assembly of the invention has the important advantage of not requiring lubrication. As is standard practice in engineering, lubricant is applied to sliding parts and in a fluid-operated motor having sliding parts supply of lubricant is necessary at regular intervals. (Lubrication being usually performed by an oil mist in the air supply). When the valve parts are enclosed, as is normal in valves for use with fluid-operated motors, regular lubrication service introduces a complication into the operation of these motors. Fluid-operated motors are frequently used in servomechanisms and therefore the reduction in servicing achieved by the preferred embodiment of the present inven tion is an advantage.

Embodiments of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings which show axial sections of two pneumatic valve assemblies with the parts in the rest position.

The first assembly (shown in FIG. ll) comprises a valve housing which includes four parts attached rigidly together. A disclike rear member 1 is attached to an annular intermediate part 26 and a central part 13 with the aid of screws 8 (of which one is shown). Together these three housing parts enclose a generally cylindrical housing space within which the moving parts of the valve are positioned. A front housing part R5 of conical shape contains means for transferring power from the assembly to a driven member (which is not shown). The rear member 1 has a supply port 28 extending through it for the introduction of air under pressure into the housing; an exhaust port 29 is positioned in the central part 113.

Between the opposed annular areas of the housing parts 113 and 15, which are clamped together by screws (not shown) or other suitable means, is clamped the periphery of a thrust diaphragm M. The diaphragm forms the flexible front wall of the space enclosing the valve parts. A diaphragm plate 16 is secured to the diaphragm 14 with the aid of screws 18 extending through the diaphragm 14 to cooperate with a member on the rear face of the diaphragm. The plate 16 has an internally threaded central bore which receives a main shaft 19. The shaft 19 has a rearwardly directed face 19A positioned at the rear end of the bore. A helical return spring 17 contacts the plate 116 and biases the plate to the rear away from the position of the driven member.

The member on the rear face of the diaphragm is a cylindrical sleeve 22 having an outwardly directed radial projection 22A which contacts the diaphragm 14 and receives the screws 18. At the other (rear) end of the sleeve is an inwardly directed radial projection which has an annular surface 228 within the sleeve. The thrust diaphragm has a central aperture so that a cylindrical bore 30 is formed. within the diaphragm M and sleeve 22. Reciprocating movement of the diaphragm causes similar movement in the sleeve 22, plate 16 and shaft 19 which are rigidly attached to the central part of the diaphragm. An elongate spindle 20 positioned axially and centrally within the housing space has its front end extending into the bore 30. The front end has an enlarged head 20A which is spaced from the walls of the bore but cooperates with the annular surface 228. Thus movement of the diaphragm M to the front will cause the spindle 20 to move forward after the surface 223 has contacted the head 20A. When rearward movement of the diaphragm occurs the rear-face 19A of the shaft 19 will contact the head 20A to move the spindle rearwardly.

In some embodiments of the invention the spindle may be deflected under gravity so that a sliding contact exists between the head 20A and the inner surface of bore 30. For this purpose the surfaces can be coated with a low friction material for example molybdenum disulfide. It should be noted that the contact pressure will be very low because these surfaces are not load-bearing, thus no in-service lubrication will be required. The spindle 20 is supported. at its rear end at the center of an inlet diaphragm 7 which is peripherally supported between the rear member 1 and intermediate part 26. Ports 7A are positioned in the diaphragm 7 to allow passage of air from the supply port 28 into the housing space. These ports 7A allow the supply port 28 to be positioned rearwardly of the diaphragm 7 so as to reduce the volume between diaphragms 6 and 7 as low as possible.

The spindle is rigidly attached to the diaphragm by means of a threaded nut 5, washer 4 and resilient seal 3 which are placed on an extension of the spindle. The rear member 1 has a blind bore to receive these fixing members'so that the inlet diaphragm can lie on the front surface of the member ll.

An inlet valve plate 2 is rigidly attached to the front face of the inlet diaphragm between a rim on the spindle and the diaphragm front face. The plate 2 carries an annular resilient valve member 2A which extends forward from the plate. Coaxial with the spindle 20 and embracing it is a valve member 24 which comprises a cylindrical part having at its forward end an annular inwardly radial projection which acts as a seat for a first helical spring 25. The rear end of this spring contacts the valve plate 2 within the annular valve member 2A. The spring 25 biases the inlet diaphragm 7 and the member 24 apart. The rear end of the valve member 24 has an annular outwardly radial projection 24A, the rear face of which acts as a valve seat for the reception of the valve member 2A. From the diagram it will be seen that when the biasing force of the spring 25 is overcome the valve member 2A and seat 24A can be brought together so that the supply port 28 cannot supply air under pressure to the thrust diaphragm 14. The member 24 is supported in the housing space by a support diaphragm 6 which is peripherally held between the intennediate part 26 and the central part 13; the member 24 extends through a central hole in the diaphragm. The member 24 is slidable relative to the diaphragm but the diaphragm is retained in contact with the front face of seat 24A. Ports 24B are provided so that fluid flow through 24 is not restricted. A disc-shaped stop plate 27 is positioned against the front face of diaphragm 6 and is in sliding contact with the member 24. A stop member 13A of annular form projects inwardly from the central member 13 into the forward path of the periphery of plate 27 and thus limits the forward movement of the member 24.

An exhaust valve member 23 comprises a cylinder positioned coaxially and externally relative to the spindle 20 and member 24. The rear end of the cylinder has an annular projection 23A extending radially inwardly, the rear face of the projection contacting the stop plate 27. The projection 23A acts as a seat for one end of a second helical spring 21 which contacts the projection 22A of the sleeve 22 which, together with the member 24, lies within this spring 21. The spring 21 thus biases the projection 23A from the thrust diaphragm 14 and, through the projection 23A, the members 23 and 24.

The forward end of thecylinder has a radially outwardly projecting flange which carries an annular resilient valve member 238 on its rear face. A second stop member 13B projects inwardly from the central part 13 to interrupt the rearward path of the valve member 23B and provide an annular valve seat to receive the member 238. When the member 23B is on its seat the exhaust port 29 is closed off from the housing space.

A silencer 11 supported on annular resilient members 9, 12 is positioned in the exhaust port to reduce the noise output in the exhausted air, and to prevent ingress of foreign matter.

The operation of the valve assembly which causes reciprocation of the diaphragm 14 when air under pressure is supplied constantly to supply port 28, will now be described. For convenience the components consisting of the valve member 24, the support diaphragm 6, the stop member 27 and the exhat st valve member 23 will be referred to as the central subassembly. As will be seen hereafter this subassembly moves as a single unit when the valve is in operation and although the components are only in sliding contact together and perform different functions. in practice the spring 21 (which biases the central valve part rearwardly) retains the projection 23A, stop member 27 and support diaphragm 6 in contact against the valve seat 24A.

ln the accompanying diagram all the valve parts are shown in the rest position in which the diaphragm is in its extreme rear position. It will be seen that the outlet valve is closed and the inlet valve is open The diaphragm has been moved to this rear position by the return spring 17 and the diaphragm operates through its power stroke to the power position (in which the diaphragm 14 is in its forward position) and then follows the exhaust stroke to return to the rest position.

The air under the valve is supplied through port 28, and, passing through the aperture 7A exerts pressure on the diaphragm 14 because the supply port is in communication with the diaphragm through the channel between the spindle 20 and the valve member 24. Thus, the first movement to occur from the rest position is that the thrust diaphragm moves forward with the other components remaining in the position shown. After travelling through a certain distance the spindlehead 20A is contacted by the surface 228 and further movement of the diaphragm drags the spindle 20 forward. As the spindle 20 is pulled forward the first spring 25 is compressed, but this spring is selected so that the central subassembly components which are biased from the inlet diaphragm 7 by this spring 25 will not be moved by compression of the spring. It will be appreciated that as the diaphragm 14 moves forward the compression of the spring 21 is reduced so that the biasing force retaining the central subassembly and the diaphragm 14 apart is reduced. The dimensions of the exhaust valve 23 and diaphragm 6 are selected so that the net fluid pressure exerted on the exhaust valve is rearwards at this point in the operation.

After travelling through a second distance the thrust diaphragm has pulled the inlet diaphragm forward a certain distance so that the valve member 2A contacts the valve seat 24A thus closing the inlet valve from the rear face of the thrust diaphragm. It is to be noted that at this point the inlet air pres- 'sure still acts on the rear face of the support diaphragm 6 and also on the rear face of diaphragm 7 within the annular valve member. Now that the inlet valve is closed the central subassembly is in direct mechanical contact with the spindle 20 and further forward movement of this spindle (or an increase in pressure on the supply side of diaphragms 6 and 7) will open the outlet valve between the valve member 23B and the valve seat 13B so that air under pressure can escape from the housing space. '1

It is possible for the diaphragm 6 to lift from the surface of member 24 due to the air pressure exerted on its rear face. However, the inner periphery of the diaphragm maintains contact with the stop member and seals the air under pressure from the thrust diaphragm. i

Forward movement of the central subassembly and hence also of the spindle 20 is prevented by'the bringing into abutment of the stop member 27 and the stop face 13A. It is at this point that the-valve components reach their forward position (the power position) having executed the power stroke. The air pressure supplied to the housingspace will of necessity have been of sufficient value to overcome the compression of the return spring 17 and the return spring acts so as to return the valve components through the exhaust stroke to the rest position. As the diaphragm commences its rearward movement the spring 21 commences to be compressed but it will be remembered that the air pressure at the supply port is still present on the rear face of the support diaphragm 6 and part of the rear area of diaphragm 7 and the dimensions and flexibility of this diaphragm and the properties of the spring 21 are selected so that the valve 23 remains open while the diaphragm 14 is moving to the rear. The pressure in the supply port is still acting on the rear face of the support diaphragm 6 and also on the central part of the inlet diaphragm 7. I

The. inlet valve is opened w en the rear face 19 A of the shaft 19 strikes the front faces of the spindle head 20A. This contact forces the spindle 20 rearwards and opens the inlet valve by causing the valve member 2A to separate from the valve seat 24A. As the air pressure builds up within the housing space pressure is equalized on the'diaphragm 6 and valve 23 so that the central valve part is moved rearwards under the action of spring 21. The components then reach the positions shown and the cycle is repeated. 1

The driven member may be a shaft carrying a ratchet wheel which is stepwise rotated by a pawl on the end of the main shaft. Thus reciprocation of this shaft is translated into rotary motion.

The embodiment of FIG. 2 will now be described.

It should be noted that the integers common to this embodiment and the embodiment of FIG. 1 have common reference numerals and new reference numerals are used to describe the modifications existing between the two embodiments.

In the accompanying drawings, the first modification to which attention will be drawn relates to the helical spring 34L which biases the rear valve part rearwardly. This biasing member contacts the valve plate 2 on the forward face of diaphragm 7 and its front end seats on the annular ledge 33 positioned near the rearward end of sleeve 22.. A rear plate 32 is provided in contact with diaphragm 7. Comparing the present embodiment with that shown in H6. 1, it will be noted that previously the spring 25 contacted the valve member 24. In the previous embodiment the central valve parts were retained in position by the opposed forces in the springs 21! and 25. However, in the present embodiment, in order to retain the central valve parts together it is necessary to retain them against the projection 24A by means of resilient annular member 36. This member 36 seats in an annular groove on the outer surface of the cylindrical part of member 24. An annular rigid insert 37 between parts 23 and 24 provides a seat for spring 21L An O-ring seal 35 is provided in the central valve part to provide sealing between the members.

The use of this longer helical spring provides an increased rearward load on the rear valve part when this moves to open the inlet valve. It also reduces the force on the rear valve part when the part is snapping to the exhaust position.

A nonreturn valve comprising a Nylon ball 45 forwardly biased by a helical spring 44 is provided in parallel with the valve mechanism to ensure that the power chamber of the motor can be exhausted without regard to the position of the component parts of the valve. It will be noted that the spring extends rearwardly to contact the valve housing part l and the corresponding aperture must be formed in each of the intervening housing parts and diaphragm. it will be seen that the ball 43 closes a duct leading from the volume immediately adjacent the rear face of the diaphragm lid. When the ball 43 is lifted from its seat this volume can communicate with the inlet chamber of the mechanism via the cutaway portion in diaphragm 7.

In the rear valve assembly an adjustment collar 3% has been introduced between the plate 2 and a rearwardly directed face on the spindle 20. When the valve components are assembled the length of the collar can be selected to allow for tolerances in the components. it will be appreciated that selection of the appropriate collar size will determine the first position at which mechanical contact occurs between the spindle and the sleeve 22.

The silencer assembly has also been modified and the annular cylindrical silencer member 39 is held on annular seats by means of clips 40. This assembly ensures that the silencer ring is firmly held on its seat across the exhaust ports. it will be noted that the housing part 13 (as then numbered) in the copending application, has been modified into two parts ll3A and 1133 in the present embodiment. it will be seen that the nonreturn valve requires a sealing ring All where the helical spring M passes through the abutment faces of these parts.

An optional feature of this embodiment is a pressure-relief valve which is formed by a Nylon ball d5 biased to close a duct which communicates with the volume immediately rearward of the diaphragm M. The valve member is biased by spring 46 and the biasing force is variable by means of a threaded screw 47 which has a locking nut lb. Sealing rings 12; and d9 are provided where necessary. This pressure-relieving valve allows the maximum thrust of the motor mechanism to be regulated to avoid damage to the driven mechanism by overloading. As stated previously, this pressure-relieving valve is an optional feature and will be omitted on mechanism designed to operate with specific pressure supplies.

it will be noted that the inlet duct cooperates with the dish part on the front face of housing part l by means of a tluttt' 23A, the function of which is to ensure that the inlet pressure acts on the whole of the rear of diaphragm 7.

It will be seen that the components forward of the thrust diaphragms 114 have been omitted for clarity but there will be provided a surface near position 311 for contacting the spindle as the thrust diaphra m moves rearwardly.

The invention has een described with particular reference to pneumatic operation, but the invention also contemplates the use of the fluid-valve assembly with a suitable hydraulic liquid.

1 claim:

1. A fluid-operated valve assembly, capable of providing automatic reciprocation when fluid pressure is applied, comprising a. a housing,

b. a thrust diaphragm peripherally held at one end of the housing, adapted for connection to a driven member, and movable from a first to a second position, movement to said second position being the result of the pressure of fluid within the housing,

0. a first bias member which biases the diaphragm to the first position, I

d. a diaphragm-supported rear valve part connected to the thrust diaphragm and movable with it between a first and a second position,

e. a second bias member which biases the rear valve part rearwardly,

f. a diaphragm-supported central valve part, and

g. a third bias member which biases the central valve part into a first position wherein it forms a fluid-exit seal, the central valve part being movable into a second position by the action of said rear valve part moving into a second position at which position the said rear valve part and said central valve part form a fluid-inlet seal and said central valve part no longer forms a fluid-exit seal.

2. A valve assembly as claimed in claim 1 in which the inlet seal is formed between the rear valve part and a valve seat on the central valve part.

3. A valve assembly as claimed in claim 1 in which the diaphragm supporting the rear valve part is apertured and positioned between the thrust diaphragm and an inlet port.

4. A valve assembly as claimed in claim 1 in which a contact member extends toward the thrust diaphragm from the rear valve part and carries a first contact surface which is contacted by a part of the thrust diaphragm at the first position so tat the rear valve part is thereafter moved toward the thrust diaphragm.

5. A valve assembly as claimed in claim 4 in which the con tact member carries a second contact surface which is contacted by a part of the thrust diaphragm as this diaphragm moves to its first position so that the rear valve part is moved toward its first position.

6. A valve assembly as claimed in claim 5 in which the contact member is received in a bore in the thrust diaphragm.

7. A valve assembly as claimed in claim 1 in which the outlet seal is fonned by an outlet valve member on the central valve part which separates an outlet port from the thrust diaphragm when seated on a valve seat surface on the housing.

d. A valve assembly as claimed in claim 7 in which the valve seat surface faces the diaphragm so that the outlet-valve member separates from it when the central valve part moves toward the diaphragm.

ii. A valve assembly as claimed in claim l in which the central valve part includes a stop member which limits the movement of the central valve part by contacting a surface on the housing.

Claims

1. A fluid-operated valve assembly, capable of providing automatic reciprocation when fluid pressure is applied, comprising a. a housing, b. a thrust diaphragm peripherally held at one end of the housing, adapted for connection to a driven member, and movable from a first to a second position, movement to said second position being the result of the pressure of fluid within the housing, c. a first bias member which biases the diaphragm to the first position, d. a diaphragm-supported rear valve part connected to the thrust diaphragm and movable with it between a first and a second position, e. a second bias member which biases the rear valve part rearwardly, f. a diaphragm-supported central valve part, and g. a third bias member which biases the central valve part into a first position wherein it forms a fluid-exit seal, the central valve part being movable into a second position by the action of said rear valve part moving into a second position at which position the said rear valve part and said central valve part form a fluid-inlet seal and said central valve part no longer forms a fluid-exit seal.

5. A valve assembly as claimed in claim 4 in which the contact member carries a second contact surface which is contacted by a part of the thrust diaphragm as this diaphragm moves to its first position so that the rear valve part is moved toward its first position.

7. A valve assembly as claimed in claim 1 in which the outlet seal is formed by an outlet valve member on the central valve part which separates an outlet port from the thrust diaphragm when seated on a valve seat surface on the housing.

8. A valve assembly as claimed in claim 7 in which the valve seat surface faces the diaphragm so that the outlet-valve member separates from it when the central valve part moves toward the diaphragm.

9. A valve assembly as claimed in claim 1 in which the central valve part includes a stop member which limits the movement of the central valve part by contacting a surface on the housing.