NZ239385A - Pneumatic control spool valve with internal pilot passageways and intensifier pistons to reverse spool movement after time delay - Google Patents

Description

239 3o5 Patents Form No 5 Prior::/Da Jo(s): Complete S;;:;cifio;i!ion Filed: tt-sKAi! I . BWwjiso..

PUbli«:=n Date: P.O. Journs!, No: .......

Patents Act 1953 COMPLETE SPECIFICATION M.Z. PATENT QFFICE 13 AUG 1991 fiEcetvr-a "PNEUMATIC VALVE" We, Goyen Controls Co Pty Limited, a Company incorporated under the laws of the State of New South Wales, and situated at 268 - 292 Milperra Road, Milperra, New South Wales, 2214, both States being in the Commonwealth of Australia, hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- 051498.M3 239 38 5 This invention relates to a pneumatic or compressed air valve for controlling the direction of flow in a pneumatically powered circuit. It more specifically relates to such a valve commonly known as a five-way two-position spool type; in this case it is adapted for pneumatic pilot operation between its two positions. In a derivative application of the valve it relates to the valve being a component of an integrally constructed time delay valve having compact dimensions together with a relatively wide range of time delay settings in the context of an all pneumatic valve of the type. Hereinafter such a valve will be referred to as "a valve of the type described".

The valve of the invention is intended to overcome or ameliorate disadvantages of already known valves of the type described, as listed below, or to provide at least a new and better choice among alternatives.

The disadvantages are: (i) The functions of a valve of the type described is not available in a single "envelope" as an integrally constructed valve; whilst the same functions can be achieved using only air as the energy medium by an interconnection of several pneumatic valves, it could not be achieved with a single unit; (ii) Conventional valves of the type described tend to be unreliable in switching quickly and positively between the extreme spool positions. Particularly where a pneumatically controlled time delay of long duration (e.g. 30 seconds) is required, the spool is inclined to translate sluggishly, possibly stalling in a neutral position, so causing malfunction; (iii) The alternative electrically timed and switched pneumatic valves often are not suitable due to a non-inherent flame or explosion-proof character. Often also it is not convenient to require electricity merely for control of pneumatic power when pneumatics are the preferred major energy source at a point of use. (iv) Pneumatically timed valves require an enclosed space to act as a reservoir; a double acting or two-position valve would require two reservoirs or their equivalent of a single reservoir divided into two fixed size spaces. The overall dimensions thus required to house the reservoir volume tend with 23 9385 conventional valves of the type to be large if the range of time delays accommodated is to be wide (e.g. 5 to 30 seconds); (v) An interconnection of valves to perforin the function of the valve of the type 5 described would not generally enable a neat modular assembly of housings with shared common dimensions. Thus there would not be an opportunity to minimise as far as possible the numbers of separate items required to support a manufacturing programme producing a range of pneumatic valves.

The invention consists of a pneumatic valve of the nominal five-way two position spool type adapted for a pneumatic pilot actuated translation of the spool between two extreme positions that it can occupy in a body of the valve in order to, by translation, to sequentially switch a supply of compressed bulk air supplied to an inlet port from one outlet port to a second outlet port and vice versa, all said 15 ports being located in the body, wherein the pilot operation derives its actuation energy for each translation of the spool from pilot air bled through internal passages in the valve body intercommunicating with a respective one of each of the two output ports and wherein the pilot air required to energise each translation of the spool is directed to act upon an intensifier piston assembly moveable within an 20 intensifier cylinder located within a housing mounted at either end of the valve body containing the spool and wherein the pilot air exerts force upon one side of the piston assembly whilst the other side of the piston assembly is configured to bear upon an adjacent end of the spool and wherein the intensifier piston assembly comprises a first piston having a small diameter and a second piston having a larger 25 diameter whereby the pilot air pressure acts, firstly during one spool translation on the first piston only and secondly on both pistons during that spool translation and wherein the intensifier cylinder has a small diameter chamber and a large diameter chamber respectively dimensioned to operatively house the small and large pistons.

In operation, upon initiation of the valve, the small piston responds to pilot air pressure build-up by exerting an initial force to initiate movement of the - " H reciprocable parts of the valve, that is, the spool and each intensifier piston assembly. When the spool is moved far enough to reverse the valve bulk air flow 35 direction, the small piston passes out of the small chamber of the intensifier - 3 0 EC 1993 cylinder. The pilot air pressure energy stored in the small chamber thus is released suddenly into the then available portion of the large chamber where it acts upon the large piston resulting in a suddenly applied substantially increased force that accelerates the reciprocable parts of the valve to the opposite end, resulting in the bulk air flowing from the pressure port of the valve to one outlet port being 23 diverted quickly to the other outlet port. The sequence of events then reverses, and continues to do so, so reversing the flow direction for such time as air is supplied to the pressure port of the valve, on each reversal causing the reciprocable parts to shuttle between either end position.

Preferably in a second aspect of the invention the valve further comprises an integrally attached time delay module comprising a reservoir in a reservoir housing, the reservoir being in the form of an elongate bore and containing a single floating piston configured to be reciprocable between each opposed end of said bore and wherein the reservoir housing is attached to the body of the valve, there being 10 internal passageways provided to allow internal communication between the small chamber of the intensifier piston and an adjacent one end of the said bore.

The significance of the provision of a single floating piston reciprocable between opposed ends of the elongate bore of the reservoir housing is that an approximately 15 30 second time delay can be built into the valve according to the second aspect of the invention whilst the reservoir as a whole only occupies a space approximately equal to that occupied by a valve according to the first aspect of the invention. To have achieved this result otherwise would have required either a physically much larger reservoir or, the orifice in which the tapered needle is entered to throttle 20 the bleed air would not be able to be manufactured using conventionally available drilling means and would be prone to blockages by airborne grit, dust or other particles.

In use, the time delay module allows the shuttling of the spool of the valve to be 25 reduced to a relatively slow rate in the context of a pneumatically timed valve, namely approximately twice per minute. The valve according to the second aspect of the invention may be controlled by the pilot air-bleed adjusting screws to shuttle between approximately 2 and 12 times per minute.

Preferably in the valve the pilot air is bled through a restricted internal passage able to be throttled separately for a flow direction to either one of said outlet ports by the positioning of a tapered needle in an orifice comprising a part of the passage. ' , f.: N ,■ H ^ v & 1994 ^ 23 9 7: .9 Preferably in the valve the position of the needle in the orifice is adjustable by use of an adjusting screw and is retainable by a lock nut.

Preferably the valve further comprises a manual pilot rod extending outwardly 5 co-axially from the intensifier piston assembly at each end and that can protrude from the intensifier cylinder housing at either end when the spool is at its extreme position closer to the respective end.

Preferably in the valve the small piston comprises a U-shaped cross-section cup 10 washer member made of a resilient material such as moulded neoprene.

Preferably in the valve an intersection between the small and large chambers comprises a frusto-conical lead-in region of the cylindrical wall of the small chamber.This enables the peripheral lip of the cup washer member to be guided into 15 the small chamber on each return direction stroke.

Preferably in the valve the manual pilot rods are configured to form a coaxial exhaust air passage portion between the rod and the wall of the intensifier piston housing through which the said pilot rod protrudes.

Preferably in the valve a second exhaust air passage portion is provided interconnecting the coaxial exhaust air passage portion and a common exhaust air passage provided to exhaust said intensifier cylinder. in operation of the valve, during the travel of the floating piston, air on its one unpressurised side is forced through the passage intercommunicating with the intensifier piston chamber, through said first and second exhaust air passage portions, and out of the valve by the common exhaust air passage.

The significance of the provision of the supply of air exhausted from the reservoir to the outside of the valve via the manual pilot rod between its locating and guiding clearance with its housing is that the air volume available to flush dust, dirt and the like out of the clearance greatly exceeds the volume of air potentially able to draw such dust and dirt inwardly into that region of the valve. Thus the 35 chances of a build-up of potentially failure causing dirt in the valve are greatly reduced. -5- <r' r<-' nvt! 1 • v '; 1994 23 9 3 85 The invention is described according to a first and second aspect of it by way of example with reference to the accompanying illustrations in which: Fig 1 is a perspective view of a valve according a first aspect of the invention 5 coupled with a time delay module to provide a timer delayed valve according to a second aspect of the invention; and Fig 2 is a cross-sectional view of the valve of Fig 1 sectioned on the plane ll-ll.

Referring to Figs 1 and 2 the air-piloted valve 10 according to a first aspect of the invention comprises a valve body 12 to which is bolted two intensifier cylinder housings 14A and B.

With particular reference to Fig 1, provision for attachment of a source of supply 15 of bulk compressed air is made in the valve body 12 at threaded port (or way) P.

Provision for exhaust of air is made at two ports R. On the opposite face (hidden in Fig 1), two output ports A and B are provided by which bulk air can be connected to a component such as a double-acting pneumatic cylinder (not shown).

With reference to Fig 2 the ports are correspondingly identified by the passage ways communicating with the ports, such as P and R visible in Fig 1. As visible in Fig 2, the valve body 12 houses an assemblage of five port modules for ports R, A, P, B and R, several annular spacers 16 and eight elastomeric seals 18. Spool 20 is located co-axially with and inside the five port modules, spacers 16 and seals 18, to slide axially therein. The spool 20 is illustrated in Fig 2 at its extreme right hand end of travel. Identical components to the left hand side of the centre line V-Y may be referred to by reference numbers followed by the letter A and to the right by the same reference number followed by the letter B, where such a distinction may assist understanding of the illustration. Every reference number 30 indicates an identical component on each side of the centre line Y-Y in this preferred embodiment.

In the following description the words "inner" and "inward" used to mean, in respect of a numbered item, the side or end closer to the centre line, "outer" and "outward" to mean the side or end of an item further from the centre line.

I- 1394 239 38 Each end of spool 20 is recessed to receive the inner end 22 of an intensifier piston assembly 24 which extends axially outwardly to include a large piston 26, small piston 28 and manual pilot rod 30. Small piston 28 comprises a U-shaped cross-section elastomeric moulded member supported by its inner side by the outer 5 face of the large piston 26 and retained on the outer side by boss 32. Manual pilot rod 30 is provided to extend axially outwardly from boss 32 to pass through the end wall 34 of each intensifier cylinder housing 14.

The intensifier large piston 26 and small piston 28 are located inside an 10 intensifier cylinder 36 comprising a small chamber 38 intercommunicating with a large chamber 40.

The intercommunication between the small chamber 38 and the large chamber 40 may include a frusto-conical entrance 42.

A small diameter pilot bleed passage 44 is made in the valve body 12 connecting each supply port A and B to its respective closer end face 46A or 46B of the valve body 12. A pilot bleed passage 48 is formed in the intensifier cylinder housing 14 to align with passage 44 upon assembly of the housings 14 to the body 12.

Co-axial with passage 48 and communicating with its outer end is a restricted orifice 50. Co-axial with orifice 50 and communicating with its outer end is a larger passage 52 which extends outwardly to the end wall 34 of the intensifier cylinder housing 14.

Branching from larger passage 52 is a further passage 53 intercommunicating with small chamber 38.

Larger passage 52 is threaded towards its outer end to receive an adjusting screw 54 30 which comprises plain shaft portion 56 occupying without clearance the cross-section of passage 52, and a tapered needle 58 extending from the inner end of the plain shaft portion 56 of the adjusting screw 54extending in an inward direction so as to enter orifice 50 and be axially adjustable for position therein by rotation of the screw 54. 23 9 An exhaust outlet passage 60 from the large chamber intercommunicates with a common exhaust main 62.

Reference to the left hand side small chamber 38 more clearly shows the exhaust 5 provisions associated with the small chamber, as follows. Manual push rod 30 carries on it a seal 64 which closes off concentric exhaust passage 66 from small chamber 38 except when the intensifier piston assembly 24A is in its innermost position. Then the intensifier cylinder 36 is open to exhaust main 62 via passage 68.

The dividing line between valve 10 and time delay module 80 is the line of the 15 exhaust main 62-62.

The operation of valve 10 is as follows. A bulk supply of compressed air is piped to the valve 10 at port P. Ports A and B are piped to a pneumatically powered device such as a double-acting pneumatic cylinder which is desired to be 20 continuously reciprocated. To initiate the valve, the spool and intensifier pistons as a unit, must be manually piloted to one end of the valve body such as to the right hand end as illustrated.

Describing the operation in terms of the initial spool position in the valve as 25 illustrated, compressed air initially flows from port P to port B. When port B is pressurised, air bleeds along pilot bleed passages 44 and 48, through orifice 50 and further passage 53 into small chamber 38. When the pressure rises in small chamber 38 the endwise force tends to push small piston 28 and hence the right hand intensifier piston assembly 24B, spool 20 and left hand intensifier piston assembly 30 24A ("the reciprocable parts") to the left.

A further intercommunication passage 70 passes from the lower wall of the small chamber 38 which may be co-linear with passage 53 previously described. The passages 70 are, to time delay module 80 to be further described below.

M £ T (') F o b 5 As the right hand side small piston 28B moves to the left its flexible elastomeric lip reaches the end of the frusto-conical entrance 42 before the spool 20 has moved a sufficient distance to alter the bulk air flow direction through the valve.

Because of the frictional resistance to motion of the reciprocable parts of the 5 valve the pressure in the small chamber 38 builds to a relatively high level before motion ensues. When the elastomeric lip clears the junction between the small and large chamber the pressure energy stored in the small chamber 38 is released suddenly into the portion of the volume of the large chamber between the large piston and the outer end of the large chamber.

The release of air into the large chamber causes the available air pressure to act suddenly on the total effective area of the small plus large piston. This provides an impulsive force to drive the reciprocable parts to the left, so causing the bulk airflow direction to be reversed from the P-to-B direction to the P-to-A direction.

As shown in Fig 2, the time delay module 80 is provided with a reservoir 82 in the form of an elongate straight cylindrical bore formed in a housing which may be of extruded aluminium. The ends are closed off with end caps 86 secured to either end of reservoir housing 84. The time-delay module is attached to the valve body 12 by a pair of tubular bushes 88, each half-in-half recessed and sealed into the housings of the reservoir 82 and intensifier cylinders 14. Two openings 90 are provided in the wall of the reservoir housing so that, upon assembly of the module 80 to the valve 10, there exists alignment between each of the openings 90, the tubular bore of the tubular bushes 88 and the interconnection O .tV' 239 38 5 passages 70 at each attachment point to provide an intercommunication path between each small chamber 38 and one adjacent end of the reservoir 82. The time delay module 80 is secured to the valve 10 with attachment bolts 92 shown in Fig 1.

Inserted in the reservoir 82 before closure of both end caps is a floating piston 94. The floating piston 94 is provided with a seal 96 and extension pieces 98 symmetrically extending from either side of the plane of the seal 96 so that the plane of the seal 96 is limited in its range of movement between the two openings 90 in the wall of reservoir 82. The extension pieces 98 may be, as illustrated, tubular and integral parts of the floating piston. In that case a circumferential groove 100 is provided in each extension piece together with a hole connecting each groove 100 to the interior of the reservoir on its respective side of the floating piston 94.

The valve 10 with time delay module 80 functions as follows. With reference to Fig 2, reciprocable parts of the valve are shown at the stage of imminent translation from right to left. This is because pilot air bleeding into small chamber 38B has also flowed through the opening 90B in the reservoir wall and has caused pressure build-up in the reservoir 82 to move the floating piston 94 to move to its extreme 20 left hand position. Once in this position the pressure will further increase in small chamber 38 relatively quickly to the stage where it initiates the translation of the reciprocable parts as already described.

The operation which would follow that right to left translation would include 25 pressurised air bleeding through small chamber 38A and opening 90A into the available volume of reservoir 82 to the left hand side of floating piston 94. The resistance to motion of piston 94 is low so that it would move first, in preference to the intensifier piston assembly 24A. Piston 94 would then move across to the right hand end of reservoir 82, the speed of that movement being slow if orifice 50A 30 were adjusted substantially blocked by tapered needle 58A, or substantially faster if a lesser blockage of the orifice were set.

While the piston 94 is progressing along the length of the reservoir 82, air on the non-pressurised side is exhausted through opening 90 into small chamber 38 and out 35 of the valve via two potential paths. The first path is through restricted orifice 239 38 5 50 and the second major path is along concentric exhaust passage 66 and passage 68 to exhaust main 62. This enables a relatively large volume of air to flush out potentially damage causing dust and dirt which might otherwise tend to accumulate and enter the internal parts of the valve via the exhaust main 62.

Using conventional drilling techniques for producing the orifice 50 and conventional manufacturing techniques for producing the tapered needle 58, the valve illustrated may be manufactured so as to be readily capable of adjustment to reverse flow direction of full line pressure between 2 and 12 times per minute, as set by adjustment of screws 54.

Claims (10)

WHAT WE CLAIM IS: 97 fl 7 Q C «-o ^ ,J O 0

1. A pneumatic valve of the nominal five-way two position spool type adapted for a pneumatic pilot actuated translation of the spool between two extreme positions that it can occupy in a body of the valve in order to, by translation, to sequentially switch a supply of compressed bulk air supplied to an inlet port from one outlet port to a second outlet port and vice versa, all said ports being located in the body, wherein the pilot operation derives its actuation energy for each translation of the spool from pilot air bled through internal passages in the valve body intercommunicating with a respective one of each of the two output ports and wherein the pilot air required to energise each translation of the spool is directed to act upon an intensifier piston assembly moveable within an intensifier cylinder arrangement located within a housing mounted at either end of the valve body containing the spool and wherein the pilot air exerts force upon one side of the piston assembly whilst the other side of the piston is configured to bear upon an adjacent end of the spool and wherein the intensifier piston assembly comprises a small area piston and a large area piston on which the pilot air pressure acts, firstly on the small area and secondly on both areas, during each spool translation and wherein the intensifier cylinder arrangement has a small diameter chamber and a large diameter chamber respectively dimensioned to house the small and large area pistons.

2. A pneumatic valve as claimed in claim 1 further comprising an integrally attached time delay module comprising a reservoir in a reservoir housing, the reservoir being in the form of an elongate bore and containing a single floating piston configured to be reciprocable between each opposed end of said bore and wherein the reservoir housing is attached to the body of the valve, there being internal passageways provided to allow internal communication between the small chamber of the intensifier cylinder arrangement and the adjacent one end of said opposed end of the said bore.

3. A pneumatic valve as claimed in either one of claim 1 or claim 2 in which the pilot air is bled through either of two restricted internal passages able to be throttled separately for a flow direction to either one of said outlet ports by the positioning of a tapered needle in either of two orifices ^ i Ct> comprising respective parts of each said passage. ^ , 23 9 385

4. A pneumatic valve as claimed in claim 3 in which the position of the needle in the orifice is adjustable by use of an adjusting screw and is retainable by a

5. A pneumatic valve as claimed in any one of the previous claims further comprising a manual pilot rod extending outwardly co-axially from the intensifier piston assembly at each outer end and that can protrude from the intensifier cylinder housing at either end when the spool is at its extreme position closer to the respective end.

6. A pneumatic valve as claimed in any one of the previous claims in which the small piston comprises a U-cup made of a resilient material such as moulded

7. A pneumatic valve as claimed in any one of the previous claims in which an intersection between the small and large chambers comprises a frusto-conical lead-in region of the cylindrical wall of the small chamber.

8. A pneumatic valve as claimed in claim 5 in which the manual pilot rods are configured to form a coaxial exhaust air passage portion between the rod and the wall of the intensifier piston housing through which the said pilot rod protrudes.

9. A pneumatic valve as claimed in claim 8 in which a second exhaust air passage portion is provided interconnecting the coaxial exhaust air passage portion and a common exhaust air passage provided to exhaust said intensifier cylinder.

10. A pneumatic valve substantially as described and illustrated with reference to Figures 1 and 2. GOYEN CONTROLS CO PTY LIMITED lock nut. neoprene. 051498 -13-