EP0067048B1 - A pump - Google Patents
A pump Download PDFInfo
- Publication number
- EP0067048B1 EP0067048B1 EP82302879A EP82302879A EP0067048B1 EP 0067048 B1 EP0067048 B1 EP 0067048B1 EP 82302879 A EP82302879 A EP 82302879A EP 82302879 A EP82302879 A EP 82302879A EP 0067048 B1 EP0067048 B1 EP 0067048B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- spool
- chamber
- fluid
- spool chamber
- passage
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000012530 fluid Substances 0.000 claims description 55
- 230000007423 decrease Effects 0.000 claims description 3
- 238000013022 venting Methods 0.000 description 10
- 230000004323 axial length Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 2
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
Images
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01L—CYCLICALLY OPERATING VALVES FOR MACHINES OR ENGINES
- F01L25/00—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means
- F01L25/02—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means by fluid means
- F01L25/04—Drive, or adjustment during the operation, or distribution or expansion valves by non-mechanical means by fluid means by working-fluid of machine or engine, e.g. free-piston machine
- F01L25/06—Arrangements with main and auxiliary valves, at least one of them being fluid-driven
- F01L25/066—Arrangements with main and auxiliary valves, at least one of them being fluid-driven piston or piston-rod being used as auxiliary valve
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B43/00—Machines, pumps, or pumping installations having flexible working members
- F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
- F04B43/06—Pumps having fluid drive
- F04B43/073—Pumps having fluid drive the actuating fluid being controlled by at least one valve
Definitions
- the invention relates to a pump of the kind comprising two chambers, each chamber having an inlet and an outlet for pumped fluid, the inlet and the outlet being controlled by respective valves, wherein a part of the wall of each chamber is formed of a respective diaphragm, the pump further comprising a rigid connection between the diaphragms of respective chambers whereby movement of the diaphragms increases the volume of one chamber and decreases the volume of the other chamber, an inlet for an operating fluid, and a directing means for directing the operating fluid alternately to respective enclosed spaces which are adjacent those surfaces of respective diaphragms which are outside the chambers, the directing means comprising a spool which is slidable between two positions in a spool chamber, a first passage leading from the operating fluid inlet to the spool chamber, and second and third passages leading from the spool chamber to respective ones of said spaces, wherein, when the spool is in a first 6f said positions, the first passage communicates with the second passage
- venting of both ends of the spool chamber is prevented. Only at the end of each stroke is venting of one or other end of the spool chamber permitted. When venting of the ends of the spool chamber is prevented or restricted, both ends of the spool will be subjected to a substantial pressure and longitudinal movement of the spool will not continue. If an attempt is made to operate the pump at high speed, venting of one end of the spool chamber may be substantially restricted before longitudinal movement of the spool has been completed and thus the required reciprocation of the spool may fail to occur.
- a pump of the kind referred to has control means movable with the diaphragms throughout their strokes for directing fluid, separately from the fluid directed to said enclosed spaces, to the ends of the spool chamber alternately, for controlling flow of fluid from ends of the spool chamber and for preventing supply of fluid to one end of the spool chamber when fluid is directed by the control means to the opposite end of the spool chamber.
- Fluid is directed to each end of the spool chamber over a fraction only of the range of movement of the diaphragms, the magnitude of that fraction being selected to ensure that the spool reciprocates fully at all operating speeds of the pump.
- FIG. 1 shows a pump 10 of the kind commonly referred to as a double diaphragm pump.
- the pump comprises a main inlet 11 and passages 12 and 13 leading from the inlet to respective chambers 14 and 15.
- a valve 16 at the inlet of chamber 14 and a valve 17 at the inlet of chamber 15 are capable of closing respective chambers from the main inlet.
- Passages 20 and 21 lead from chambers 14 and 15 respectively to a common main outlet 22.
- Valves 18 and 19 at the outlets of respective chambers 14 and 15 can close said chambers from the main outlet.
- the valves 16 to 19 are non-return valves and are suitably of a "ball" or "clack" kind.
- the volumes of the chambers 14 and 15 vary during the operation of the pump 10.
- a plate 23 and a diaphragm 24 surrounding the plate forms a part of the boundary of chamber 14.
- the diaphragm provides a flexible sealed connection between the plate and the remainder of the boundary of the chamber.
- a part of the boundary of the chamber 15 is defined by a plate 25 and a further diaphragm 26 arranged in the same manner as the plate 23 and diaphragm -24.
- the plate 23 and diaphragm 24 also define a part of the boundary of an enclosed space 31 outside the chamber 14 and the plate 25 and diaphragm 26 form a part of the boundary of a corresponding space 32 outside the chamber 15.
- the pump has a main driving fluid inlet 45 through which air under pressure can be supplied from an external source to the pump to drive the diaphragms.
- Actuating means 30 is provided for directing pressurised air alternately to the spaces 31 and 32 in order to exert pressure on the diaphragms alternately.
- the pump also includes control means 9 which is movable with the diaphragms for controlling operation of the actuating means 30 in such a manner that air is directed to one of the spaces 31 and 32 and exhausted from the other space until the diaphragms together reach one limit position and then movement of both diaphragms is reversed by directing air to the other of the spaces 31 and 32 and venting the one space.
- the control means 9 comprises a connecting member in the form of a rod 27 which extends between the plates 23 and 25 and, in conjunction with the plates, provides a rigid connection between the diaphragms 24 and 26.
- the diaphragms and plates have apertures through which end portions of the rod extend, the plates being secured on the end portions of the rod.
- the rod 27 is constrained by a housing 28 to move along an axis 29 defined by the rod and the diaphragms are constrained to reciprocate together with the rod.
- the consequent decreasing pressure in chamber 15 serves to hold inlet valve 17 open and outlet valve 19 closed so that material to be pumped is drawn from inlet 11, through passage 13 into the chamber.
- the increasing pressure in chamber 14 serves to hold inlet valve 16 closed and outlet valve 18 open so that material is driven out of the chamber along passage 20 to outlet 22.
- the reverse occurs upon movement of the rod to the right.
- the rod can in an alternative embodiment be connected directly to respective diaphragms.
- the actuating means 30 comprises a spool chamber 33 which contains a spool 34.
- the spool has a central land 35 and recesses 36 and 37 on opposite sides of the land. These recesses are preferably annular.
- Opposite end portions 38 and 39 of the spool act as pistons within the spool chamber.
- These end portions and the land 35 are cylindrical about an axis 40 of the spool chamber and are a free sliding fit in the spool chamber so that sliding of the spool is not impeded but there is no substantial gap between the peripheral boundary of the spool chamber and the end portions and land of the spool.
- the movement of the spool 34 in one direction is limited by end face 44 of the spool chamber 33 which engages end face 43 of piston portion 39 when the spool is in a first limit position, as shown in Figure 2. Movement of the spool in the opposite direction is limited by end face 42 of the chamber which engages end face 41 of piston portion 38 when the spool has travelled from the first position shown in Figure 2 or Figure 3 to a second limit position (not shown).
- the inlet passage 45 leads to a port 50 of the spool chamber 33, which port 50 is approximately equally spaced from the opposite ends of the chamber.
- Passages 46 and 47 lead to spaces 31 and 32 respectively from respective further ports 51 and 52 which are equally spaced in opposite axial directions from the centre of the spool chamber and from the port 50.
- Outlet passages 48 and 49 lead from respective ports 53 and 54 of the spool chamber to the housing 28.
- the ports 53 and 54 are spaced axially between port 50 and end face 42, and port 50 and end face 44 respectively.
- the passage 46 defines the sole path for flow of fluid into and from the space 31 so that the spool 34 controls both flow of fluid to this space and venting of the space.
- the passage 47 defines the sole path for flow of fluid into and from the space 32 so that the spool controls both flow of fluid to this space and venting thereof.
- Land 35 and piston portion 39 each provide a seal which ensures that fluid passing along the spool chamber through recess 37 from passage 47 leaves the actuating means by outlet passage 49.
- passages which extend through the interior of the spool.
- an axial end face of the land 35 is adjacent to port 50, and an inwardly directed axial face of either piston portion is adjacent a respective outlet passage when the spool is in the first or second position.
- Transfer of the spool 34 between the first and second positions occurs when the control rod 27 reaches a limit position.
- a passage 61 leads from the source of operating fluid to a port 62 in the housing 28.
- the port occupies a central position in the housing.
- Outlet passages (not shown in Figure 2) lead from ports 63 and 64 and may suitably combine with outlet passages 48 and 49 to provide a path by which fluid can leave the pump and be discharged to atmosphere.
- the ports 63 and 64 are equally spaced apart on either side of the inlet port.
- the rod 27 is a free sliding fit in portions of the housing adjacent to the outlet ports 63 and 64 and inlet port 62.
- Seals 65 which are positioned axially on either side of each of the ports, serve to prevent fluid leaking along the interface between the internal surface of the housing and the surface of the control rod.
- the seals may comprise 0-rings.
- the housing Between the inlet port 62 and each of the outlet ports 63 and 64, the housing defines respective annular spaces 66 and 67 about the control rod. Further passages 68 and 69 lead from respective annular spaces 66 and 67 to respective end portions of the spool chamber 33 at the end faces 42 and 44. In the rod there are two recesses in the form of annular grooves 70 and 71 which communicate with respective annular spaces 66 and 67.
- the ports 62, 63 and 64 are sealed from the further passages 68 and 69.
- the control rod 27 cooperates with the seals 65 to prevent supply of air from the passage 61 to either end of the spool chamber 33.
- the control rod in particular the surfaces thereof defining the grooves 70 and 71, direct air from the passage 61 to one end of the spool chamber and permit air to flow from the other end of the spool chamber to the ambient atmosphere through a corresponding one of the passages 63 and 64.
- groove 71 provides a path for operating fluid from port 62 about a seal 65 to annular space 67. Fluid is thereby permitted to pass from the source via further passage 69 to an end of the spool chamber 33 between piston portion 39 and end face 44.
- groove 70 provides a passage from annular space 66 around a seal 65 to outlet port 63. Fluid is thereby permitted to evacuate the space between piston portion 38 and end face 42. The pressure of fluid on end face 43 of the piston portion is sufficient to drive the spool along the spool chamber to the second position. Operating fluid is thereby redirected to space 32 to drive the rod in the opposite direction, to the right as shown in Figure 2. The grooves will accordingly move out of communication with ports 63 and 62 which become closed from annular spaces 66 and 67 by the seals 65.
- each of the grooves remains in communication with a respective annular space 66 and 67 during the operating cycle of the pump and is never aligned with one of the outermost seals 65. It is therefore not possible for any pumped fluid which has passed into either of spaces 31 or 32 across a fractured diaphragm to enter the actuating means via either of the grooves.
- the distance between corresponding edges of the grooves, dimension B in Figure 2 is slightly greater than the distance between the inlet port and either of the outlet ports, dimension A.
- Figure 3 illustrates the control means of a modified version of the pump shown in Figures 1 and 2.
- the general arrangement of the pump illustrated in Figure 3 is the same as that of the pump illustrated in Figures 1 and 2 and the preceding description is deemed to apply to the pump of Figure 3, except for the differences hereinafter mentioned.
- the control rod 127 of the pump shown in Figure 3 is formed with three V-shaped grooves, 172, 173 and 174.
- the grooves may be annular.
- the housing for the control rod defines a single annular space 175 surrounding a central part of the control rod.
- the groove 173 establishes communication between an inlet port 162 and a passage 170 which leads to the other end of the spool chamber. Accordingly, air is admitted to this other end of the spool chamber and is exhausted from the one end of the spool chamber to cause the spool to be driven from the position shown in figure 3.
- the spool and spool chamber of the pump illustrated in Figure 3 are arranged in the same manner as are the corresponding parts of the pump of Figures 1 and 2 and reciprocation of the spool causes the operating fluid for the pump to be redirected as hereinbefore described.
- the groove 172 establishes communication between the passage 170 and the outlet port 163 whilst the groove 173 establishes communication between the inlet port 162 and the passage 169.
- the spool chamber is preferably formed in a body which is separable from the housing of the control rod.
- An elastomeric gasket, designated 80 in Figure 2 and 180 in Figure 3 is provided at the interface between this body and the housing of the control rod, in order to prevent leakage of fluid at the interface from those passages which extend between the spool chamber and the control rod.
- Both of the pumps illustrated may be modified by the provision of at least one bleed passage which provides communication between part of the spool chamber through which fluid under pressure flows to one or other of the diaphragms and part of the spool chamber to which fluid is directed by the control rod.
- the bleed passage or each bleed passage may be provided in or adjacent to the gasket between the body containing the spool chamber and the housing of the control rod.
- a groove may be cut in the gasket to extend between two of the passages.
- a bleed passage formed in the gasket extends between the passage 46 and the passage 68.
- air is permitted to bleed at a relatively low rate from the passage 46 to the passage 68 and the corresponding end of the spool chamber. This maintains a substantial pressure on the end face 41 of the spool to ensure that the spool is moved fully to and is held in the required position engaging the end face 44 of the spool chamber.
- the end portion of the spool chamber adjacent to the face 44 is vented by a further bleed passage, formed in the gasket, and extending between the passage 69 and the passage 47.
- bleed passages avoids any tendancy for the spool to stitch in an intermediate position in which the central land 35 partly covers the inlet passage 45 and restricts the supply of air to one or other of the spaces 31 and 32.
- the bleed passages provided in the gasket would be of small cross-sectional area, compared with the cross-sectional area of the flow passage extending to and from the spool chamber.
- the passages extending to and from the spool chamber are typically 10 mm to 12 mm in diameter, it is intended that the bleed passages be between 0.5 mm and 1 mm in diameter.
- bleed passages may be formed in respective piston portions 38 and 39 of the spool. It will be noted that such bleed passages do not provide for the continuous supply of air under pressure from the inlet 45 to both ends of the spool chamber, since only one of the recesses in the spool is in communication with the air inlet passage at any one time.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Reciprocating Pumps (AREA)
Description
- The invention relates to a pump of the kind comprising two chambers, each chamber having an inlet and an outlet for pumped fluid, the inlet and the outlet being controlled by respective valves, wherein a part of the wall of each chamber is formed of a respective diaphragm, the pump further comprising a rigid connection between the diaphragms of respective chambers whereby movement of the diaphragms increases the volume of one chamber and decreases the volume of the other chamber, an inlet for an operating fluid, and a directing means for directing the operating fluid alternately to respective enclosed spaces which are adjacent those surfaces of respective diaphragms which are outside the chambers, the directing means comprising a spool which is slidable between two positions in a spool chamber, a first passage leading from the operating fluid inlet to the spool chamber, and second and third passages leading from the spool chamber to respective ones of said spaces, wherein, when the spool is in a first 6f said positions, the first passage communicates with the second passage, and, when the spool is in the second of said positions, the first passage communicates with the third passage.
- In published European Patent Application Number 0018143 of Wilden Pump & Engineering Company, there is disclosed a pump of the kind referred to wherein there is a clearance space between the periphery of the spool and the wall of the spool chamber sufficient for working fluid to pass from a fluid inlet beside the spool to both ends of the spool chamber continuously during operation of the pump. Vent passages are provided for venting respective end portions of the spool chamber and venting of the spool chamber through these passages is controlled by a rigid control rod extending between the diaphragms. It is indicated that alternate venting of the end portions of the spool chamber will cause reciprocation of the spool.
- During a major part of the stroke of the control rod of the pump disclosed in the aforesaid published application, venting of both ends of the spool chamber is prevented. Only at the end of each stroke is venting of one or other end of the spool chamber permitted. When venting of the ends of the spool chamber is prevented or restricted, both ends of the spool will be subjected to a substantial pressure and longitudinal movement of the spool will not continue. If an attempt is made to operate the pump at high speed, venting of one end of the spool chamber may be substantially restricted before longitudinal movement of the spool has been completed and thus the required reciprocation of the spool may fail to occur.
- According to the present invention, a pump of the kind referred to has control means movable with the diaphragms throughout their strokes for directing fluid, separately from the fluid directed to said enclosed spaces, to the ends of the spool chamber alternately, for controlling flow of fluid from ends of the spool chamber and for preventing supply of fluid to one end of the spool chamber when fluid is directed by the control means to the opposite end of the spool chamber.
- Fluid is directed to each end of the spool chamber over a fraction only of the range of movement of the diaphragms, the magnitude of that fraction being selected to ensure that the spool reciprocates fully at all operating speeds of the pump.
- An example of a pump in accordance with the invention will now be described with reference to the accompanying drawings wherein:-
- Figure 1 shows diagrammatically a pump with parts thereof cut away;
- Figure 2 shows diagrammatically and on an enlarged scale certain parts of the pump of Figure 1, the pump again being partly cut away; and
- Figure 3 illustrates in a manner similar to that of Figure 2 the actuating mechanism of a second example of pump.
- Figure 1 shows a
pump 10 of the kind commonly referred to as a double diaphragm pump. The pump comprises amain inlet 11 andpassages respective chambers valve 16 at the inlet ofchamber 14 and avalve 17 at the inlet ofchamber 15 are capable of closing respective chambers from the main inlet. -
Passages chambers main outlet 22. Valves 18 and 19 at the outlets ofrespective chambers valves 16 to 19 are non-return valves and are suitably of a "ball" or "clack" kind. - The volumes of the
chambers pump 10. Aplate 23 and adiaphragm 24 surrounding the plate forms a part of the boundary ofchamber 14. The diaphragm provides a flexible sealed connection between the plate and the remainder of the boundary of the chamber. A part of the boundary of thechamber 15 is defined by aplate 25 and afurther diaphragm 26 arranged in the same manner as theplate 23 and diaphragm -24. Theplate 23 anddiaphragm 24 also define a part of the boundary of an enclosedspace 31 outside thechamber 14 and theplate 25 anddiaphragm 26 form a part of the boundary of acorresponding space 32 outside thechamber 15. - Various fluids, including air, are suitable for driving the pump. The pump has a main driving fluid inlet 45 through which air under pressure can be supplied from an external source to the pump to drive the diaphragms. Actuating means 30 is provided for directing pressurised air alternately to the
spaces spaces spaces - The control means 9 comprises a connecting member in the form of a
rod 27 which extends between theplates diaphragms rod 27 is constrained by ahousing 28 to move along anaxis 29 defined by the rod and the diaphragms are constrained to reciprocate together with the rod. - Movement of the rod, plates and diaphragms in a direction to the left, as shown in Figure 1, serves to decrease the volume of
chamber 14 and increase the volume ofchamber 15. The consequent decreasing pressure inchamber 15 serves to holdinlet valve 17 open andoutlet valve 19 closed so that material to be pumped is drawn frominlet 11, throughpassage 13 into the chamber. Simultaneously, the increasing pressure inchamber 14 serves to holdinlet valve 16 closed andoutlet valve 18 open so that material is driven out of the chamber alongpassage 20 tooutlet 22. The reverse occurs upon movement of the rod to the right. It will be apparent that the rod can in an alternative embodiment be connected directly to respective diaphragms. - As shown in Figure 2, the actuating means 30 comprises a spool chamber 33 which contains a spool 34. The spool has a
central land 35 and recesses 36 and 37 on opposite sides of the land. These recesses are preferably annular.Opposite end portions land 35 are cylindrical about anaxis 40 of the spool chamber and are a free sliding fit in the spool chamber so that sliding of the spool is not impeded but there is no substantial gap between the peripheral boundary of the spool chamber and the end portions and land of the spool. - The movement of the spool 34 in one direction is limited by
end face 44 of the spool chamber 33 which engagesend face 43 ofpiston portion 39 when the spool is in a first limit position, as shown in Figure 2. Movement of the spool in the opposite direction is limited by end face 42 of the chamber which engages end face 41 ofpiston portion 38 when the spool has travelled from the first position shown in Figure 2 or Figure 3 to a second limit position (not shown). - The
inlet passage 45 leads to aport 50 of the spool chamber 33, whichport 50 is approximately equally spaced from the opposite ends of the chamber.Passages 46 and 47 lead tospaces further ports 51 and 52 which are equally spaced in opposite axial directions from the centre of the spool chamber and from theport 50.Outlet passages respective ports housing 28. Theports port 50 and end face 42, andport 50 andend face 44 respectively. - The passage 46 defines the sole path for flow of fluid into and from the
space 31 so that the spool 34 controls both flow of fluid to this space and venting of the space. Similarly, thepassage 47 defines the sole path for flow of fluid into and from thespace 32 so that the spool controls both flow of fluid to this space and venting thereof. - When the spool 34 is in the first limit position in spool chamber 33, shown in Figure 2, air is directed by the spool to pass from
inlet passage 45 to passage 46 and thence tospace 31adjacent plate 23 anddiaphragm 24 of thechamber 14. The fluid is able to pass along the spool chamber through recess 36.Land 35 provides a seal against fluid passing into thepassage 47, andpiston portion 38 similarly provides a seal against fluid enteringoutlet passage 48. - At the same time as a path from
inlet passage 45 to passage 46 is open, a path frompassage 47 tooutlet passage 49 is also open.Land 35 andpiston portion 39 each provide a seal which ensures that fluid passing along the spool chamber through recess 37 frompassage 47 leaves the actuating means byoutlet passage 49. In place of recesses in the external surface of the spool 34, there may be provided passages which extend through the interior of the spool. - It can be seen that, as fluid is directed through the spool chamber to
space 31, thecontrol rod 27 is driven to the left causing fluid to be expelled fromspace 32 through the spool chamber viaoutlet passage 49. When the spool is at the opposite end of the spool chamber from that shown in Figure Z, a path betweeninlet passage 45 andpassage 47, and a further path between passage 46 and outlet .passage 48 are open, and the reverse operation will occur. The length of the path of the spool in the spool chamber is approximately equal to the combined axial extent ofland 35 and theport 50. The axial distance between theports 51 and 52 is approximately equal to the addition of the axial length of theport 50 and twice the axial length ofland 35. The axial length ofpiston portions adjacent port 53 and end face 42 or betweenport 54 andend face 44 of the spool chamber. - Thus, an axial end face of the
land 35 is adjacent toport 50, and an inwardly directed axial face of either piston portion is adjacent a respective outlet passage when the spool is in the first or second position. - Transfer of the spool 34 between the first and second positions occurs when the
control rod 27 reaches a limit position. As shown in Figure 2, apassage 61 leads from the source of operating fluid to aport 62 in thehousing 28. The port occupies a central position in the housing. - Outlet passages (not shown in Figure 2) lead from
ports outlet passages ports rod 27 is a free sliding fit in portions of the housing adjacent to theoutlet ports inlet port 62.Seals 65, which are positioned axially on either side of each of the ports, serve to prevent fluid leaking along the interface between the internal surface of the housing and the surface of the control rod. The seals may comprise 0-rings. - Between the
inlet port 62 and each of theoutlet ports annular spaces Further passages 68 and 69 lead from respectiveannular spaces annular grooves 70 and 71 which communicate with respectiveannular spaces - For the greater part of the operating cycle of the pump, and as illustrated in Figure 2, the
ports further passages 68 and 69. Thecontrol rod 27 cooperates with theseals 65 to prevent supply of air from thepassage 61 to either end of the spool chamber 33. - When the
rod 27 reaches one of its two limit positions, two of theseals 65 are ineffective because they surround one or other of thegrooves 70 and 71 in the control rod. The control rod, in particular the surfaces thereof defining thegrooves 70 and 71, direct air from thepassage 61 to one end of the spool chamber and permit air to flow from the other end of the spool chamber to the ambient atmosphere through a corresponding one of thepassages - With the pump at the stage of its operating cycle shown in Figure 2, the
rod 27 is moving to the left and approaching the first limit position. When the rod has reached the limit position, groove 71 provides a path for operating fluid fromport 62 about aseal 65 toannular space 67. Fluid is thereby permitted to pass from the source viafurther passage 69 to an end of the spool chamber 33 betweenpiston portion 39 andend face 44. At the same time,groove 70 provides a passage fromannular space 66 around aseal 65 tooutlet port 63. Fluid is thereby permitted to evacuate the space betweenpiston portion 38 and end face 42. The pressure of fluid onend face 43 of the piston portion is sufficient to drive the spool along the spool chamber to the second position. Operating fluid is thereby redirected tospace 32 to drive the rod in the opposite direction, to the right as shown in Figure 2. The grooves will accordingly move out of communication withports annular spaces seals 65. - The fluid which has been retained between end faces 43 and 44 is sufficient to hold the spool in the second position until the converse of the above described operation takes place. This will occur when groove 71 moves into alignment with one of the
seals 65 adjacent to the outlet port 64 (to establish communication between this port and space 67) andgroove 70 moves into alignment with anotherseal 65 adjacent toinlet port 62, when the rod is at the second limit position. - It will be noted that each of the grooves remains in communication with a respective
annular space spaces - Figure 3 illustrates the control means of a modified version of the pump shown in Figures 1 and 2. The general arrangement of the pump illustrated in Figure 3 is the same as that of the pump illustrated in Figures 1 and 2 and the preceding description is deemed to apply to the pump of Figure 3, except for the differences hereinafter mentioned.
- The
control rod 127 of the pump shown in Figure 3 is formed with three V-shaped grooves, 172, 173 and 174. The smallest radius of each groove, measured from the intersect of the V to the axis of the rod, lies within the range one half to five sixths of the radius of a main portion of the rod. In the example illustrated, the minimum radius is approximately two thirds that of the main portion of the rod. In an alternative embodiment the grooves may be annular. The housing for the control rod defines a singleannular space 175 surrounding a central part of the control rod. When thecontrol rod 127 reaches a first limit position, groove 174 establishes communication betweenoutlet port 164 andpassage 169 leading to one end of thespool chamber 133. At the same time, thegroove 173 establishes communication between aninlet port 162 and apassage 170 which leads to the other end of the spool chamber. Accordingly, air is admitted to this other end of the spool chamber and is exhausted from the one end of the spool chamber to cause the spool to be driven from the position shown in figure 3. - The spool and spool chamber of the pump illustrated in Figure 3 are arranged in the same manner as are the corresponding parts of the pump of Figures 1 and 2 and reciprocation of the spool causes the operating fluid for the pump to be redirected as hereinbefore described.
- At the second limit position of the
control rod 127 shown in Figure 3, thegroove 172 establishes communication between thepassage 170 and theoutlet port 163 whilst thegroove 173 establishes communication between theinlet port 162 and thepassage 169. - In both the pump illustrated in Figures 1 and 2 and the pump illustrated in Figure 3, the spool chamber is preferably formed in a body which is separable from the housing of the control rod. An elastomeric gasket, designated 80 in Figure 2 and 180 in Figure 3, is provided at the interface between this body and the housing of the control rod, in order to prevent leakage of fluid at the interface from those passages which extend between the spool chamber and the control rod.
- Both of the pumps illustrated may be modified by the provision of at least one bleed passage which provides communication between part of the spool chamber through which fluid under pressure flows to one or other of the diaphragms and part of the spool chamber to which fluid is directed by the control rod. Conveniently, the bleed passage or each bleed passage may be provided in or adjacent to the gasket between the body containing the spool chamber and the housing of the control rod. Thus, a groove may be cut in the gasket to extend between two of the passages.
- In one example of a pump as illustrated in Figures 1 and 2 but modified by the provision of two bleed passages, a bleed passage formed in the gasket extends between the passage 46 and the passage 68. Thus, when air under pressure is directed from the
inlet passage 45 through the passage 46 to thespace 31, air is permitted to bleed at a relatively low rate from the passage 46 to the passage 68 and the corresponding end of the spool chamber. This maintains a substantial pressure on the end face 41 of the spool to ensure that the spool is moved fully to and is held in the required position engaging theend face 44 of the spool chamber. The end portion of the spool chamber adjacent to theface 44 is vented by a further bleed passage, formed in the gasket, and extending between thepassage 69 and thepassage 47. - The provision of the bleed passages avoids any tendancy for the spool to stitch in an intermediate position in which the
central land 35 partly covers theinlet passage 45 and restricts the supply of air to one or other of thespaces - It will be understood that, if movement of the spool within the spool chamber is not completed before the
control rod 27 moves out of its limit position, supply of air under pressure other than through a bleed passage to one end portion of the spool chamber would be interrupted and the spool may fail to reciprocate fully. This could lead to the control rod failing to complete its stroke so that the pump stalls. - The bleed passages provided in the gasket would be of small cross-sectional area, compared with the cross-sectional area of the flow passage extending to and from the spool chamber. Thus, whilst the passages extending to and from the spool chamber are typically 10 mm to 12 mm in diameter, it is intended that the bleed passages be between 0.5 mm and 1 mm in diameter.
- In place of bleed passages formed in the gasket, bleed passages may be formed in
respective piston portions inlet 45 to both ends of the spool chamber, since only one of the recesses in the spool is in communication with the air inlet passage at any one time.
Claims (6)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT82302879T ATE10776T1 (en) | 1981-06-06 | 1982-06-03 | PUMP. |
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8117397 | 1981-06-06 | ||
GB8117397 | 1981-06-06 | ||
GB8210093 | 1982-04-05 | ||
GB8210093 | 1982-04-05 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0067048A2 EP0067048A2 (en) | 1982-12-15 |
EP0067048A3 EP0067048A3 (en) | 1983-02-09 |
EP0067048B1 true EP0067048B1 (en) | 1984-12-12 |
Family
ID=26279709
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP82302879A Expired EP0067048B1 (en) | 1981-06-06 | 1982-06-03 | A pump |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP0067048B1 (en) |
DE (1) | DE3261533D1 (en) |
GB (1) | GB2102509B (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB2120733B (en) * | 1982-03-17 | 1987-02-11 | Walspar Engineering Limited | Valve system for pumps |
GB2164728B (en) * | 1982-03-17 | 1987-02-11 | Walspar Engineering Limited | Valve system |
US5616005A (en) * | 1994-11-08 | 1997-04-01 | Regents Of The University Of California | Fluid driven recipricating apparatus |
CN105065239A (en) * | 2015-07-24 | 2015-11-18 | 朱陈伟 | Explosion-proof-type kinetic energy output device |
Family Cites Families (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3791768A (en) * | 1972-06-16 | 1974-02-12 | W Wanner | Fluid pump |
US3849033A (en) * | 1973-06-01 | 1974-11-19 | Dorr Oliver Inc | Air pressure-actuated double-acting diaphragm pump |
DE3066127D1 (en) * | 1979-04-13 | 1984-02-23 | Wilden Pump & Eng | Air driven diaphragm pump |
US4242941A (en) * | 1979-05-14 | 1981-01-06 | Wilden Pump & Engineering Co. | Actuator valve |
-
1982
- 1982-06-03 EP EP82302879A patent/EP0067048B1/en not_active Expired
- 1982-06-03 DE DE8282302879T patent/DE3261533D1/en not_active Expired
- 1982-06-07 GB GB08216528A patent/GB2102509B/en not_active Expired
Also Published As
Publication number | Publication date |
---|---|
GB2102509B (en) | 1984-09-05 |
DE3261533D1 (en) | 1985-01-24 |
GB2102509A (en) | 1983-02-02 |
EP0067048A2 (en) | 1982-12-15 |
EP0067048A3 (en) | 1983-02-09 |
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