EP4594638A1

EP4594638A1 - Pump stroke extension apparatus and method

Info

Publication number: EP4594638A1
Application number: EP22960215.6A
Authority: EP
Inventors: Xueshui Wu; Xiaochuang SONG; Zaixing You
Original assignee: Graco Minnesota Inc
Current assignee: Graco Minnesota Inc
Priority date: 2022-09-30
Filing date: 2022-09-30
Publication date: 2025-08-06
Also published as: WO2024065587A1; EP4594638A4; CN119855982A

Abstract

A pump includes a piston disposed within a pump body that reciprocates along a pump axis to pump fluid. An air valve is actuated between open and closed states to drive reciprocation of the piston. A stroke limiter is disposed around the piston and is configured to interface with the air valve to actuate the air valve. The stroke limiter includes a spring chamber that disposes a limit spring at least partially on an opposite axial side of an interface between the stroke limiter and the pump body from the air valve.

Description

PUMP STROKE EXTENSION APPARATUS AND METHOD

BACKGROUND

The present disclosure relates generally to pumps. More specifically, the present disclosure relates to air operated pumps.
Air operated pumps rely on compressed air to displace a piston along a reciprocation axis to cause pumping. The pump can include a piston disposed within an air cylinder that is acted on by the compressed air to cause reciprocation of the fluid displacer. Springs are utilized to open and close pathways that direct the compressed air to the opposite sides of the piston head to drive the fluid displacer along the reciprocation axis. The springs occupy a portion of the axial length of the pump, limiting the stroke length relative to the overall length of the pump itself.
SUMMARY
According to an aspect of the disclosure, a pump includes a pump body; a piston disposed within the pump body and configured to reciprocate along a pump axis, an air valve, and a stroke limiter supported by the piston and configured to contact the air valve to actuate the air valve from the open state to the closed state. The piston includes a piston head; and a piston shaft extending axially from the piston head. The air valve is supported by the piston head and is actuatable between the open state and the closed state. The stroke limiter includes a holder disposed around the piston shaft, the holder defining a spring chamber; a limit spring at least partially disposed within the spring chamber and extending axially towards the piston head; and a brace disposed around the piston shaft and supported by the limit spring, the brace disposed axially between the holder and the piston head. The stroke limiter interfaces with the pump body at an actuation interface to limit axial movement of the stroke limiter in an axial direction along the pump axis. The limit spring is at least partially disposed on an opposite axial side of the actuation interface from the piston head with the stroke limiter interfacing with the pump body at the actuation interface.
According to an additional or alternative aspect of the disclosure, a pump includes a pump body; a piston disposed within the pump body and configured to reciprocate along a pump axis, the piston including a piston head and a piston shaft; an air valve supported by the piston, the air valve actuatable between an open state and a closed state, the air valve directing driving air to cause the piston to move through a first stroke in a first axial direction along the pump axis with the air valve in the closed state and the air valve directing the driving air to cause the piston to move through a second stroke in a second axial direction along the pump axis with the air valve in the open state; an end spring supported by the pump body, the end spring configured to interface with the air valve to actuate the air valve from the closed state to the open state to cause the piston to change over from the first stroke to the second stroke; and a stroke limiter supported by the piston, the stroke limiter configured to interface with the air valve to actuate the air valve from the open state to the closed state, the stroke limiter including a brace flange configured to interface with the pump body at an actuation interface to limit axial movement of the stroke limiter in the second axial direction along the pump axis, and the stroke limiter including a limit spring at least partially disposed on an opposite axial side of the brace flange from the piston head.
According to another additional or alternative aspect of the disclosure, a method of pumping includes directing driving air to a first driving chamber by an air valve to drive a piston in a first axial direction along a pump axis by the driving air; engaging a holder of a stroke limiter disposed about the piston with a portion of a pump body; driving the piston in the first axial direction with the holder engaging the portion of the pump body such that the piston moves relative to the holder and compresses a limit spring within a spring chamber formed within the holder, the spring chamber extending in the first axial direction from an interface between the holder and the pump body; actuating the air valve from an open state to a closed state by the stroke limiter interfacing with the air valve; and directing the driving air to a second driving chamber by the air valve with the air valve in the closed state to drive the piston in a second axial direction along the pump axis opposite the first axial direction.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional view of a pump.
FIG. 1B is an enlarged view of detail B in FIG. 1A.
FIG. 2A is an enlarged cross-sectional view of a portion of a pump showing the pump in a first pump state.
FIG. 2B is an enlarged cross-sectional view of the portion of the pump shown in FIG. 2A, showing the pump in a second pump state.
FIG. 2C is an enlarged cross-sectional view of the portion of the pump shown in FIG. 2A, showing the pump in a third pump state.
FIG. 2D is an enlarged cross-sectional view of the portion of the pump shown in FIG. 2A, showing the pump in a fourth pump state.

DETAILED DESCRIPTION

FIG. 1A is a cross-sectional view of pump 10. FIG. 1B is an enlarged view of detail B shown in FIG. 1A. FIGS. 1A and 1B will be discussed together. Pump 10 includes pump body 12, piston 14, inlet valve 16, piston valve 18, air valve 20, end spring 22, and stroke limiter 24. Pump body 12 includes air cylinder 26, pump base 28, fluid cylinder 30, air inlet 32, air exhaust 34, fluid inlet 36, and fluid outlet 38. Piston 14 includes piston head 40, piston shaft 42, and piston seal 44. Piston head 40 includes valve passage 46 and head bore 48. Piston shaft 42 includes connector shaft 50 and piston rod 52. Piston rod 52 extends between rod ends 54a, 54b and includes receiving chamber 56, projection 58, rod bore 60, and cross-bores 62. Connector shaft 50 includes shaft bore 64. Air valve 20 includes valve cap 66, valve base 68, valve connector 70, and passage seals 72. Valve connector 70 includes fastener 74 and sleeve 76. Stroke limiter 24 includes holder 78, limit spring 80, brace 82, and bearing 84. Holder 78 extends between holder ends 86a, 86b and includes holder body 88, brace flange 90, and support flange 92.
Pump 10 is configured to pump fluid, such as liquids, such as paint, from an upstream location to a downstream location. Pumped fluid enters pump body 12 through fluid inlet 36 and exits pump body 12 through fluid outlet 38.
Pump body 12 supports other components of pump 10. Piston 14 is disposed within pump body 12 and is configured to reciprocate along pump axis PA to pump the fluid from the fluid inlet 36 to the fluid outlet 38. In the example shown, pump 10 is configured as a double displacement pump in the example shown, meaning that pump 10 outputs pumped fluid during both an upstroke, with piston 14 shifting in first axial direction AD1 along pump axis PA, and a downstroke, with piston 14 shifting in second axial direction AD2 along pump axis PA.
Pump 10 is configured as an air powered pump in the example shown. Driving air, which is compressed air provided from an air source, such as a compressor, a pressurized tank, etc., is provided to pump 10 to drive reciprocation of piston 14. In the example shown, the driving air is provided to pump 10 through air inlet 32 and is exhausted from pump 10 through air exhaust 34. Air inlet 32 provides driving air to driving chamber 104a to displace piston 14 through a stroke in first axial direction AD1. Driving air flows to driving chamber 104b to displace piston 14 through a stroke in second axial direction AD2. Driving air is exhausted from pump 10 as piston 14 displaces in first axial direction AD1. Specifically, the driving air in driving chamber 104b flows through exhaust passage 96 to exhaust chamber 108 and is exhausted through air exhaust 34.
Pump base 28 is a central portion of pump body 12. In the example shown, both driving air and pumped fluid flow within pump base 28 during operation of pump 10. Air cylinder 26 is disposed at a first axial end of pump base 28. Air cylinder 26 is mounted to pump base 28 and at least partially defines driving chamber 104a and driving chamber 104b. In the example shown, a portion of pump base 28 extends into air cylinder 26 with air cylinder 26 mounted to pump base 28. A portion of pump base 28 within air cylinder 26 forms shelf 100. In the example shown, shelf 100 is formed by the axial end face of pump body 12 that is oriented in first axial direction AD1.
Fluid cylinder 30 is disposed at a second axial end of pump base 28 opposite air cylinder 26. Fluid cylinder 30 is connected to pump base 28. Fluid cylinder 30 at least partially defines fluid chamber 106a and fluid chamber 106b through which the pumped fluid flows between fluid inlet 36 and fluid outlet 38. Inlet valve 16 is mounted to fluid cylinder 30. Inlet valve 16 is a check valve that is configured to admit pumped fluid into pump body 12 and to prevent retrograde flow of the pumped fluid through fluid inlet 36.
Piston 14 is disposed within pump body 12. Piston 14 is configured to reciprocate along pump axis PA to pump the pumped fluid from an upstream location fluidly connected to fluid inlet 36 to a downstream location fluidly connected to fluid outlet 38. Piston head 40 is disposed within air cylinder 26 and is acted on by the driving air to cause reciprocation of piston 14. Piston head 40 separates driving chamber 104a from driving chamber 104b. Piston seal 44 is supported by piston head 40 and engages the inner wall of air cylinder 26 to create an airtight seal between piston head 40 and air cylinder 26.
Head bore 48 extends fully through piston head 40. Head bore 48 is aligned on pump axis PA. Head bore 48 forms a portion of the exhaust passage 96 through piston 14. Valve passage 46 extends fully through piston head 40. Valve passage 46 is radially offset from pump axis PA. It is understood that piston head 40 can include an array of valve passages 46 arrayed annularly around pump axis PA. Valve passage 46 provides a flowpath for driving air to flow from driving chamber 104a to driving chamber 104b such that the driving air can act on piston head 40 to displace piston 14 through the stroke in second axial direction AD2. Both head bore 48 and valve passage 46 define flowpaths for driving air to flow through piston head 40.
Piston shaft 42 extends axially from piston head 40. Piston shaft 42 extends in second axial direction AD2 from piston head 40. Piston shaft 42 is connected to piston head 40 and reciprocates with piston head 40. Piston shaft 42 connects to piston head 40 at a location within air cylinder 26, extends through pump base 28, and extends into fluid cylinder 30. Piston shaft 42 extends from piston head 40, through driving chamber 104a, through exhaust chamber 108, and into fluid chamber 106b.
Piston shaft 42 engages with shaft seal 98a and shaft seal 98b that are supported by pump body 12. Shaft seals 98a, 98b are configured as dynamic seals such that a component moves relative to the shaft seals 98a, 98b during operation. In the example shown, shaft seals 98a, 98b are supported by pump body 12 and piston 14 reciprocates relative to shaft seals 98a, 98b. Exhaust chamber 108 is formed axially between shaft seals 98a, 98b. Air exhaust 34 is a port through pump body 12 that is in fluid communication with exhaust chamber 108.
Exhaust passage 96 is formed through piston 14 and is configured to provide a flowpath for driving air to exhaust from driving chamber 104b. Cross-bores 62 extend into piston shaft 42 and intersect with exhaust passage 96. Cross-bores 62 extend from the exterior of piston shaft 42 to exhaust passage 96. Cross-bores 62 provide flowpaths for driving air to exit from piston 14 into exhaust chamber 108 formed within pump body 12.
Piston shaft 42 includes connector shaft 50 that is connected to and extends from piston head 40 and includes piston rod 52 that is connected to and extends from connector shaft 50. Connector shaft 50 can be connected to one or both of piston head 40 and piston rod 52 by interfaced threading therebetween. Shaft bore 64 extends axially through connector shaft 50. Shaft bore 64 defines a portion of the exhaust passage 96 through piston 14 Shaft bore 64 provides a flowpath for driving air to flow from head bore 48 to rod bore 60.
Piston rod 52 is connected to and extends axially from connector shaft 50. Connector shaft 50 extends into piston rod 52 and is directly connected to piston rod 52. Connector shaft 50 can connect to piston rod 52 in any desired manner, such as by interfaced threading. Piston rod 52 engages with shaft seals 98a, 98b to fluidly isolate exhaust chamber 108 from driving chamber 104a and to fluidly isolate exhaust chamber 108 from fluid chamber 106b. Rod seal 102 is disposed between connector shaft 50 and piston rod 52 within rod bore 60. Rod seal 102 can be formed as an elastomer seal, such as an O-ring, among other options.
Rod end 54a is an axial end of piston rod 52 oriented towards piston head 40. Rod end 54a is oriented in first axial direction AD1. Rod end 54b is an opposite axial end of piston rod 52 from rod end 54a. Rod end 54b is oriented towards inlet valve 16. Rod end 54b is oriented in second axial direction AD2. Rod bore 60 extends into piston rod 52 from rod end 54a. Rod bore 60 extends axially within piston rod 52. Rod bore 60 forms a portion of exhaust passage 96 through piston 14.
Piston valve 18 is disposed at an opposite axial end of piston shaft 42 from piston head 40. Piston valve 18 is mounted to piston shaft 42. More specifically, piston valve 18 is mounted to piston rod 52 at rod end 54b. Piston valve 18 is carried by piston shaft 42 to reciprocate with piston 14. Piston valve 18 carries a seal that engages with the interior surface of fluid cylinder 30. Piston valve 18 separates a fluid chamber within pump 10, through which pumped fluid flows, into an upstream fluid chamber 106a and a downstream fluid chamber 106b.
Air valve 20 is supported by piston 14. In the example shown, air valve 20 is supported by piston head 40. Air valve 20 is mounted to piston head 40 such that air valve 20 travels axially with piston head 40 along pump axis PA. As discussed in more detail below, air valve 20 is movable relative to piston head 40 to open and close the flowpaths through valve passages 46 between driving chamber 104a and driving chamber 104b. Air valve 20 is actuatable between a first valve state, in which driving air can flow through valve passage 46 from driving chamber 104a to driving chamber 104b, and a second valve state, in which driving air is prevented from flowing through valve passage 46 between driving chamber 104a and driving chamber 104b. The first valve state can also be referred to as an open state. The second valve state can also be referred to as a closed state. Air valve 20 directs the driving air to cause piston 14 to move through the stroke in first axial direction AD1 with air valve 20 in the closed state and the air valve 20 directs the driving air to cause piston 14 to move through the stroke in second axial direction AD2 with air valve 20 in the open state.
Valve cap 66 is disposed on a first axial side of piston head 40. Valve cap 66 is disposed on a side of piston head 40 oriented in first axial direction AD1 and towards end spring 22. Valve cap 66 is disposed over and axially aligned with head bore 48 through piston head 40. Valve cap 66 is configured to be engaged with piston head 40 to seal the flowpath through head bore 48 while driving air is provided to driving chamber 104b to drive piston 14 in second axial direction AD2. Valve cap 66 is configured to be disengaged from piston head 40 to open the flowpath through head bore 48 while driving air is provided to driving chamber 104a to drive piston 14 in first axial direction AD1. Valve cap 66 being disengaged from piston head 40 fluidly connects driving chamber 104b with air exhaust 34 via exhaust passage 96, cross-bores 62, and exhaust chamber 108.
Valve base 68 is disposed on a second axial side of piston head 40 opposite the first axial side of piston head 40. Valve base 68 is disposed on a side of piston head 40 oriented in second axial direction AD2 and towards stroke limiter 24. Valve base 68 is disposed on an opposite axial side of piston head 40 from valve cap 66.
Passage seal 72 is supported on valve base 68. Passage seal 72 is disposed axially between valve base 68 and piston head 40. Passage seal 72 is configured to interface with piston head 40 to fluidly disconnect valve passage 46 from driving chamber 104a with air valve 20 in the second valve state. Passage seal 72 is configured to disengage from piston head 40 to fluidly connect driving chambers 104a, 104b via valve passage 46 with air valve 20 in the first valve state.
Valve connector 70 extends between and connects valve cap 66 and valve base 68. Valve connector 70 extends through valve passage 46 formed within piston head 40. Valve connector 70 can directly connect to one or both of valve cap 66 and valve base 68. In the example shown, valve connector 70 is formed by fastener 74, such as a bolt, that connects valve base 68 and valve cap 66 and sleeve 76 that axially fixes valve base 68 relative to valve cap 66. Fastener 74 extends through valve base 68 and directly connects to valve cap 66. A head of valve connector 70, which is the head of fastener 74 in the example shown, is larger than the aperture in valve base 68 that valve connector 70 extends through. The head of valve connector 70 interfacing with valve base 68 prevents valve base 68 from shifting in second axial direction AD2 and off of valve connector 70. Valve connector 70 connects valve cap 66 and valve base 68 for simultaneous movement as air valve 20 shifts between the first valve state and the second valve state. In the example shown, air valve 20 includes multiple valve connectors 70 extending between and connecting valve cap 66 and valve base 68. It is understood that air valve 20 can include one, two, three, four, or more valve connectors 70. Piston head 40 can thus include multiple one or multiple of valve passages 46 through piston head 40. Each valve connector 70 includes an associated passage seal 72. The passage seal 72 extends annularly around the valve connector 70.
End spring 22 is disposed within air cylinder 26. End spring 22 is disposed on an opposite axial side of piston head 40 from the piston rod 52. End spring 22 is disposed on an opposite axial side of piston head 40 from stroke limiter 24. End spring 22 is supported by pump body 12. In the example shown, end spring 22 is mounted to air cylinder 26. End spring 22 is mounted to pump body 12 such that piston 14 can move away from end spring 22, with piston 14 shifting in second axial direction AD2, and such that piston 14 can move towards end spring 22, with piston 14 shifting in first axial direction AD1. End spring 22 is configured to interface with air valve 20 at the end of an upstroke in first axial direction AD1. End spring 22 is configured to interface with air valve 20 to actuate air valve 20 from the second valve state to the first valve state. Specifically, end spring 22 is configured to interface with valve cap 66 to shift air valve 20 from the second valve state to the first valve state.
In the example shown, piston shaft 42 includes receiving chamber 56 that is formed in piston shaft 42. Specifically, receiving chamber 56 is formed in piston rod 52. Receiving chamber 56 is open axially towards piston head 40. Receiving chamber 56 is spaced axially from piston head 40. Projection 58 is a portion of piston rod 52 that extends to rod end 54a. Projection 58 can be a cylindrical projection that extends in first axial direction AD1 from a main body portion of piston rod 52. Receiving chamber 56 extends into the body of piston rod 52 from rod end 54a. Projection 58 defines a radial exterior of the receiving chamber 56. Receiving chamber 56 can be formed as a portion of rod bore 60 through piston rod 52. Receiving chamber 56 has a larger diameter than other portions of rod bore 60. In the example shown, receiving chamber 56 is a largest diameter portion of rod bore 60. Receiving chamber 56 has a larger diameter than the exterior diameter of connector shaft 50. While piston 14 is shown as including receiving chamber 56 into which holder 78 extends during at least a portion of the operation of pump 10, it is understood that not all examples are so limited. In some examples, piston rod 52 does not include cylindrical projection 58 that projects axially to define receiving chamber 56.
Stroke limiter 24 is supported by piston 14. Stroke limiter 24 is disposed around piston 14 and is disposed coaxially with piston 14. Stroke limiter 24 is supported by but disconnected from piston 14. Piston 14 can thus move axially relative to stroke limiter 24, as discussed in more detail below.
Stroke limiter 24 is configured to define the limit of travel of piston 14 in second axial direction AD2 through the downstroke. Stroke limiter 24 can also be referred to as a stroke extender as stroke limiter 24 facilitates a longer stroke length relative to previous pump designs. Stroke limiter 24 is configured to interface with air valve 20 at the end of a downstroke in second axial direction AD2Stroke limiter 24 to actuate air valve 20 from the first valve state to the second valve state. Specifically, stroke limiter 24 is configured to interface with valve base 68 to shift air valve 20 from the first valve state to the second valve state. A stroke length of piston 14, which is the linear distance traveled by piston 14 along pump axis PA through a stroke of the piston 14 in either of first axial direction AD1 and second axial direction AD2, is defined between
Stroke limiter 24 is configured to interface with pump body 12 at actuation interface 110 (shown in FIGS. 2B-2D) during a portion of the strokes of piston 14. The actuation interface 110 is formed between brace flange 90 and shelf 100 in the example shown. Stroke limiter 24 interfaces with pump body 12 to limit movement of stroke limiter in second axial direction AD2 along pump axis PA.
Holder 78 extends axially between holder end 86a and holder end 86b. Holder end 86a is oriented axially towards piston head 40. Holder end 86b is oriented axially away from piston head 40. Holder ends 86a, 86b can also be referred to as axial ends of holder 78. Spring chamber 94 is formed within holder 78. Specifically, spring chamber 94 is disposed radially within holder body 88. Spring chamber 94 can be a cylindrical chamber that extends fully annularly around pump axis PA. Spring chamber 94 is formed around connector shaft 50 and is disposed within holder body 88. Spring chamber 94 extends axially between holder ends 86a, 86b. Spring chamber 94 is configured to receive at least a portion of limit spring 80 during operation of pump 10. Spring chamber 94 is open in first axial direction AD1 towards piston head 40 such that limit spring 80 can extend through that open end of spring chamber 94.
Holder 78 is disposed around piston shaft 42 such that piston shaft 42 extends fully axially through holder 78. Piston shaft 42 projects axially outwards from both holder end 86a and holder end 86b. Specifically, holder 78 is disposed around connector shaft 50 and connector shaft 50 extends fully axially though holder 78 and projects through both holder end 86a and holder end 86b.
Brace flange 90 extends radially from holder body 88. In the example shown, brace flange 90 is disposed at holder end 86a. Brace flange 90 is disposed at an end of holder body 88 oriented in first axial direction AD1 and towards piston head 40. Brace flange 90 extends radially outward from holder body 88, away from pump axis PA. Brace flange 90 can extend fully annularly around pump axis PA. Brace flange 90 extends radially from holder body 88 and outward beyond the exterior of piston rod 52. Brace flange 90 has a larger diameter than the exterior of the portion of piston rod 52 at rod end 54a. Brace flange 90 has a larger diameter than the exterior of the portion of piston rod 52 defining receiving chamber 56. In some examples, brace flange 90 has a larger diameter than any portion of piston rod 52. Brace flange 90 extends radially outward and partially across the radial gap between the exterior surface of piston rod 52 and the interior surface of air cylinder 26.
Brace flange 90 extends radially from holder body 88 to axially overlap with the portion of pump body 12 that forms shelf 100. Components can be considered to axially overlap with each other when the components are disposed at a common radial location relative to an axis such that an axial line parallel to the axis extends through each of those axially overlapping components. Brace flange 90 is configured to contact shelf 100 of pump body 12 to arrest movement of holder 78 in second axial direction AD2, as discussed in more detail below. In the example shown, actuation interface 110 is formed between brace flange 90 and shelf 100.
Support flange 92 defines a closed end of spring chamber 94. While a bore extends through holder 78 to allow piston shaft 42 to pass fully therethrough, the spring chamber 94 is considered to be closed because support flange 92 extends radially inward to prevent axial movement of limit spring 80 out of spring chamber 94 in second axial direction AD2. Support flange 92 is configured to support limit spring 80. Support flange 92 is disposed at holder end 86b opposite the axial end of holder 78 at which brace flange 90 is disposed. Support flange 92 extends radially inward from holder body 88 and towards pump axis PA. Support flange 92 can be disposed fully annularly around pump axis PA. In the example shown, support flange 92 extends radially inward towards connector shaft 50 but does not contact connector shaft 50. Support flange 92 is spaced radially from connector shaft 50 to inhibit wear due to direct contact and relative movement therebetween.
In the example shown, holder 78 is configured to be at least partially disposed within piston 14 during at least a portion of a stroke of piston 14. Specifically, holder 78 is configured to be at least partially disposed within receiving chamber 56 formed in piston rod 52 during at least a portion of the strokes of piston 14. It is understood, however, that not all examples are so limited.
Limit spring 80 is disposed around connector shaft 50. Limit spring 80 is disposed axially between support flange 92 and piston head 40. Limit spring 80 is configured to bias brace 82 in first axial direction AD1. Limit spring 80 is disposed coaxially with piston 14 on pump axis PA. Limit spring 80 is at least partially disposed within spring chamber 94 formed in holder 78. With limit spring 80 extended, limit spring 80 projects axially outward from both axial sides of brace flange 90. Limit spring 80 extends in first axial direction AD1 away from brace flange 90. Limit spring 80 extends in second axial direction AD2 away from brace flange 90.
Limit spring 80 extending in second axial direction AD2 away from brace flange 90 places at least a portion of limit spring 80 on an opposite axial side of brace flange 90 from piston head 40. Limit spring 80 being at least disposed on an opposite axial side of brace flange 90 form piston head 40 facilitates disposing limit spring 80 at least partially on an opposite axial side of actuation interface 110 from piston head 40. Disposing limit spring 80 on an opposite axial side of actuation interface 110 from piston head 40 facilitates an increased stroke length for piston 14, as discussed in more detail below.
Brace 82 is supported by limit spring 80. Brace 82 is disposed around connector shaft 50. Brace 82 is configured to float relative to connector shaft 50 and is not directly connected to connector shaft 50. Brace 82 can be formed as a ring or washer, among other options. Brace 82 can extend fully annularly around pump axis PA. In the example shown, brace 82 forms the component of stroke limiter 24 that is configured to interface with valve base 68 to actuate air valve 20 to the second, closed state.
Bearing 84 is disposed at an opposite axial end of limit spring 80 from brace 82. Bearing 84 is disposed within spring chamber 94. Bearing 84 is disposed axially between limit spring 80 and support flange 92. Bearing 84 is supported on support flange 92 in the example shown. As such, support flange 92 can be considered to indirectly support limit spring 80 via bearing 84. Bearing 84 interfaces with piston shaft 42 on an inner radial side of bearing 84 and interfaces with holder 78 on an outer radial side of bearing 84. In the example shown, bearing 84 is the only component of stroke limiter 24 that directly interfaces with connector shaft 50, though it is understood that not all examples are so limited. In the example shown, bearing 84 is configured as a linear bearing that slides along connector shaft 50 as piston 14 shifts axially relative to stroke limiter 24.
FIG. 2A is an enlarged cross-sectional view of a portion of pump 10 showing pump 10 in a first pump state. FIG. 2B is an enlarged cross-sectional view of the portion of pump 10 shown in FIG. 2A, showing pump 10 in a second pump state. FIG. 2C is an enlarged cross-sectional view of the portion of pump 10 shown in FIG. 2A, showing pump 10 in a third pump state. FIG. 2D is an enlarged cross-sectional view of the portion of pump 10 shown in FIG. 2A, showing pump 10 in a fourth pump state. FIGS. 2A-2D will be discussed together and with continued reference to FIGS. 1A and 1B.
FIGS. 2A-2D illustrate the transition of pump 10 through a downstroke and subsequent changeover through an upstroke. During operation, piston 14 is configured to reciprocate through an upstroke in the first axial direction AD1 and downstroke in second axial direction AD2 to pump the pumped fluid. An example of a pump cycle, which includes both an upstroke and a downstroke, is briefly discussed below. The piston 14 is at the end of an upstroke and beginning the downstroke in the example discussed.
Driving air is provided to pump 10 through air inlet 32. For example, a compressed air source (e.g., air compressor, pressurized tank, etc. ) is connected to air inlet 32 by a hose and fitting. The driving air initially flows into driving chamber 104a. In FIG. 2A, pump 10 is in a first pump state after changing over from an upstroke to begin a downstroke. As shown in FIG. 2A, end spring 22 has actuated air valve 20 to the first valve state such that passage seal 72 is disengaged from piston head 40 and valve cap 66 is engaged with piston head 40. Valve passage 46 is open to fluidly connect driving chamber 104a with driving chamber 104b. Driving air flows into driving chamber 104a, through valve passage 46, and into driving chamber 104b. The driving air acts on piston head 40 and drives piston 14 in second axial direction AD2, increasing the volume of driving chamber 104b and decreasing the volume of driving chamber 104a.
Piston 14 moving in second axial direction AD2 causes piston valve 18 to shift to an open state and inlet valve 16 to shift to a closed state. Fluid within fluid chamber 106a can flow through piston valve 18, into fluid chamber 106b, and downstream from pump 10 through fluid outlet 38. Piston 14 displaces in second axial direction AD2 and pump 10 is placed in the second pump state shown in FIG. 2B. Pump 10 is placed in the second state during the downstroke of piston 14 and prior to piston 14 changing over to the upstroke. As shown in FIG. 2B, brace flange 90 encounters shelf 100 that is forrmed by an axial end face of pump body 12. Brace flange 90 interfaces with shelf 100 to from the actuation interface 110 between stroke limiter 24 and pump body 12. The actuation interface 110 inhibits further movement of holder 78 in second axial direction AD2. While holder 78 is prevented from shifting further in second axial direction AD2 by actuation interface 110, piston 14 continues to shift in second axial direction AD2. Piston 14 moves in second axial direction AD2 relative to stroke limiter 24.
Piston 14 continues to shift in second axial direction AD2 to transition pump 10 from the second pump state shown in FIG. 2B to the third pump state shown in FIG. 2C. Piston 14 moves relative to holder 78 and bearing 84 slides along the exterior of connector shaft 50. Piston 14 continues in second axial direction AD2 and valve base 68 encounters brace 82.
Piston 14 continuing in second axial direction AD2 with brace flange 90 braced on shelf 100 and valve base 68 engaging brace 82 compresses limit spring 80 between brace 82 and holder 78. Specifically, limit spring 80 is compressed between brace 82 and bearing 84. Limit spring 80 compresses into spring chamber 94 due to valve base 68 driving brace 82 in second axial direction AD2 and brace 82 acting on limit spring 80 in second axial direction AD2. Limit spring 80 is disposed on an opposite axial side of actuation interface 110 from piston head 40. The portion of limit spring 80 that is disposed on an opposite axial side of brace flange 90 From piston head 40 increases as limit spring 80 is compressed into spring chamber 94.
Piston 14 continues to displace brace 82 in second axial direction AD2 and compresses limit spring 80 into spring chamber 94 until brace 82 encounters holder 78. Holder 78 provides a hard stop that prevents brace 82 from shifting further in second axial direction AD2. Brace 82 seats on holder 78 at holder end 86a. Holder 78 is prevented from shifting further in second axial direction AD2 by actuation interface 110 and brace 82 is prevented from shifting further in second axial direction AD2 by holder 78.
With brace 82 engaging holder 78, limit spring 80 is at a maximum operating compression. Limit spring 80 is not compressed further with brace 82 engaging holder 78. It is understood that the maximum operating compression may not be the maximum spring compression of limit spring 80. The maximum spring compression occurs when limit spring 80 is fully compressed, which would occur if holder 78 did not engage brace to prevent brace 82 from continuing to drive limit spring 80 into spring chamber 94. As such, limit spring 80 is not fully compressed within spring chamber 94. The maximum operating compression being less than the maximum spring compression prevents undesirable wear to limit spring 80, increasing the operating life of limit spring 80, decreasing downtime of pump 10, and reducing maintenance requirements and costs.
Stroke limiter 24 interfaces with valve base 68 and acts as a stop that prevents further movement of valve base 68 in second axial direction AD2. Stroke limiter 24 braces valve base 68 such that air valve 20 is actuated to the second valve state. Piston 14 continues in second axial direction AD2 and moves relative to air valve 20 and stroke limiter 24. Air valve 20 is prevented from shifting in second axial direction AD2 with piston head 40 due to brace 82 interfacing with valve base 68. Piston 14 moving in second axial direction AD2 relative to valve base 68 causes passage seal 72 to engage with piston head 40 to seal the flowpath through valve passage 46. Driving chamber 104a is thus fluidly isolated from driving chamber 104b. Valve cap 66 is lifted off of piston head 40 due to the connection of valve base 68 and valve cap 66 by valve connector 70. Valve cap 66 lifting off of piston head 40 fluidly connects driving chamber 104b with exhaust passage 96. Pump 10 is thus transitioned to the third pump state shown in FIG. 2C.
The third pump state is associated with changeover of piston 14 from the downstroke in the second axial direction AD2 to the upstroke in the first axial direction AD1. Limit spring 80 is fully disposed within spring chamber 94 at the changeover. As shown, limit spring 80 is disposed fully outside of receiving chamber 56 at changeover from the downstroke to the upstroke, though it is understood that not all examples are so limited. While limit spring 80 is fully disposed in spring chamber 94, it is understood that limit spring 80 may not be fully compressed to the maximum spring compression. Limit spring 80 can be sized such that limit spring 80 is not fully compressed even with brace 82 interfacing with holder 78.
Limit spring 80 is at least partially disposed on an opposite axial side of actuation interface 110 than the interface between stroke limiter 24 and air valve 20. Limit spring 80 extends to radially overlap with a portion of pump body 12 disposed on an opposite axial side of actuation interface 110 from piston head 40. Components can be considered to radially overlap with each other when the components are disposed at a common axial location along an axis such that a radial line extending from the axis extends through each of those radially overlapping components. Limit spring 80 extending axially beyond actuation interface 110 in the same axial direction that piston 14 displaces during the downstroke facilitates a longer stroke length for pump 10. The axial end of limit spring 80 that is oriented towards piston head 40 and extends axially towards piston head 40 relative to actuation interface 110 would otherwise define the axial stroke length. The extension spring would fully compress and the position of that end of extension spring along pump axis PA would define the limit of movement of piston 14 by actuating air valve 20 to the first valve state. Recessing limit spring 80 on an opposite axial side of actuation interface 110 from piston head 40 facilitates piston head 40 traveling further in second axial direction AD2 before air valve 20 is actuated, thereby increasing the stroke length relative to prior art pumps.
With air valve 20 in the closed state, the driving air is prevented from flowing to driving chamber 104b from driving chamber 104a. The driving air in driving chamber 104a acts on piston head 40 and displaces piston 14 in first axial direction AD1. Limit spring 80 exerts a driving force on brace 82 in first axial direction AD1. The limit spring 80 thereby exerts a driving force on piston 14 in first axial direction AD1 through brace 82 and valve base 68.
Limit spring 80 assists piston 14 in changing over from the downstroke to the upstroke. Piston 14 is stationary at the point of changeover between the downstroke and upstroke. Limit spring 80 exerting the biasing force in first axial direction AD1 prevents stalling of pump 10 at the changeover point. Limit spring 80 assists in overcoming the fluid resistance in fluid chamber 106b that acts on piston 14 against movement in first axial direction AD1 and assists in accelerating piston 14 out of the changeover to the upstroke.
Piston valve 18 is shifts to a closed state as piston 14 shifts in first axial direction AD1 through an upstroke, thereby decreasing the volume of fluid chamber 106b and increasing the volume of fluid chamber 106a. Pumped fluid is driven downstream from fluid chamber 106b through fluid outlet 38. Piston 14 shifting in first axial direction AD1 causes inlet valve 16 to open and pumped fluid is drawn into fluid chamber 106a.
Piston 14 begins moving in first axial direction AD1 through an upstroke. The driving air contained within driving chamber 104b is driven into the exhaust passage 96 and through the exhaust passage 96 to cross-bores 62 as the volume of driving chamber 104b decreases. That driving air exits piston 14 through cross-bores 62 and flows into exhaust chamber 108. The driving air is exhausted from pump 10 through air exhaust 34 that is fluidly connected to exhaust chamber 108.
Limit spring 80 expands and pushes brace 82 in first axial direction AD1 and away from holder 78. Holder 78 initially remains seated on shelf 100 as piston 14 moves in first axial direction AD1 relative to holder 78. Piston 14 moves in first axial direction AD1 and pump 10 transitions to the fourth pump state, which occurs during an upstroke of piston 14 and prior to piston 14 changing over to a downstroke. Piston shaft 42 shifts relative to holder 78 and holder 78 shifts into receiving chamber 56 through the open end of receiving chamber 56. The axial gap between rod end 54a and brace flange 90 decreases.
Piston 14 continues to shift in first axial direction AD1 and holder 78 seated on piston shaft 42. Holder body 88 enters into receiving chamber 56 in the example shown. A portion of piston 14 (e.g., piston rod 52 and/or connector shaft 50) engages with holder 78 and carries holder 78 in first axial direction AD1. In some examples, holder end 86b engages with the base of receiving chamber 56 to seat holder 78 on piston shaft 42. In some examples, holder 78 can be considered to bottom out in receiving chamber 56. Piston shaft 42 can exert a driving force on holder 78 at the interface between holder 78 and piston shaft 42 within receiving chamber 56. In some examples, rod end 54a engages brace flange 90 to exert a driving force on holder 78 in first axial direction AD1. In other examples, rod end 54a is spaced axially from brace flange 90 with holder 78 bottomed out in receiving chamber 56. Having rod end 54a disengaged from brace flange 90 while piston 14 displaces holder 78 in first axial direction AD1 prevents distortion of and damage to brace flange 90, improving the operating life of stroke limiter 24.
Piston 14 continues in first axial direction AD1 and axially towards end spring 22. Holder 78 engages with piston shaft 42 and is carried in first axial direction AD1 such that brace flange 90 disengages from shelf 100. Piston 14 continues to transition through the upstroke and encounters end spring 22, which actuates air valve 20 to the open state. Passage seal 72 disengages from piston head 40 and driving chamber 104a is again fluidly connected to driving chamber 104b. Valve cap 66 engages piston head 40 to fluidly disconnect driving chamber 104b and exhaust passage 96. Piston 14 changes over from the upstroke to the downstroke and pump 10 is again placed in the first pump state shown in FIG. 2A. Piston 14 continues to reciprocate between respective upstrokes and downstrokes.
During portions of the operation of pump 10, holder 78 is disposed at least partially within receiving chamber 56 of piston shaft 42. Holder 78 extends into receiving chamber 56 such that portions of piston shaft 42 are disposed on both radial sides of holder 78. Holder 78 radially overlaps with both connector shaft 50 and piston rod 52. Holder 78 is disposed in receiving chamber 56 such that a radial line extending from the pump axis PA passes first through connector shaft 50, then through holder 78, and then through piston rod 52.
During other portions of the operation of pump 10, holder 78 is disposed axially outside of receiving chamber 56. Shelf 100 braces brace flange 90 and holder 78 shifts at least partially out of receiving chamber 56 such that portions of holder body 88 do not radially overlap with piston rod 52. The axial length of holder 78 that radially overlaps with piston rod 52 varies during reciprocation of piston 14.
Limit spring 80 extends into spring chamber 94 and is disposed on an opposite axial side of the hard stop formed at actuation interface 110 from the interface between stroke limiter 24 and air valve 20 that actuates air valve 20 to the closed state. Limit spring 80 extends to radially overlap with portions of pump body 12, specifically portions of pump base 28, that are disposed on the opposite axial side of actuation interface 110 from piston head 40. Such a configuration forms pump 10 that has a longer stroke length relative to previous pumps without a corresponding increase in the axial length of pump 10 itself.
During portions of operation of pump 10, limit spring 80 extends axially outward in first axial direction AD1 relative to the component of stroke limiter 24 forming the actuation interface 110 (brace flange 90 in the example shown) and towards piston head 40.Limit spring 80 recessing within spring chamber 94 during portions of the stroke of piston 14 and then extending axially out of spring chamber 94 facilitates limit spring 80 assisting in changeover of piston 14 to the upstroke while also facilitating piston 14 pumping with the increased pump stroke length.
Pump 10 and stroke limiter 24 provide significant advantages. Stroke limiter 24 is disconnected from piston 14 such that piston 14 can move relative to stroke limiter 24. Limit spring 80 is received within spring chamber 94 as piston 14 moves through the downstroke. Receiving limit spring 80 in spring chamber 94, which spring chamber 94 projects in second axial direction AD2 relative to the brace flange 90 that limits axial movement of holder 78 in second axial direction AD2, increases the stroke length of piston 14 without any associated change in the axial length of pump 10 itself. Stroke limiter 24 thereby allows for a greater stroke length, and thus a greater fluid displacement volume during a stroke, without a corresponding increase in the length of the pump body 12. Pump 10 can thus displace larger volumes of fluid with a more compact pump body 12, facilitating installation in constricted areas. Pump 10 can thus output larger volumes of pumped fluid with fewer changeovers. Piston 14 stops moving at changeover and must accelerate out of the changeover. Reducing the number of changeovers reduces wear on components of pump 10, decreasing maintenance costs and reducing downtime.
Limit spring 80 is received within spring chamber 94. In some examples, limit spring 80 does not fully compress within spring chamber 94. Compressing limit spring 80 less than full compression reduces wear on limit spring 80, improving the life of limit spring 80 and requiring less downtime and maintenance for pump 10. Limit spring 80 further assists in driving piston 14 in first axial direction AD1 and out of a changeover, preventing stalling of pump 10.
Limit spring 80 further provides a buffer for piston 14 during the process when piston 14 changes over from a downstroke to an upstroke. Air valve 20 changes over from the open state to the closed state and then piston 14 begins to decelerate until piston 14 stops moving at the changeover point. Limit spring 80 can act as a dampener that assists in decelerating piston 14 and minimizes impact between components and thus vibration to pump 10. Limit spring 80 can thereby also reduce the noise of pump 10 during operation.
While the invention has been described with reference to an exemplary embodiment (s) , it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment (s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

A pump comprising:

a pump body;

a piston disposed within the pump body and configured to reciprocate along a pump axis, the piston comprising:

a piston head; and

a piston shaft extending axially from the piston head;

an air valve supported by the piston head, the air valve actuatable between an open state and a closed state;

a stroke limiter supported by the piston and configured to contact the air valve to actuate the air valve from the open state to the closed state, the stroke limiter comprising;

a holder disposed around the piston shaft, the holder defining a spring chamber;

a limit spring at least partially disposed within the spring chamber and extending axially towards the piston head; and

a brace disposed around the piston shaft and supported by the limit spring, the brace disposed axially between the holder and the piston head;

wherein the stroke limiter interfaces with the pump body at an actuation interface to limit axial movement of the stroke limiter in an axial direction along the pump axis; and

wherein the limit spring is at least partially disposed on an opposite axial side of the actuation interface from the piston head with the stroke limiter interfacing with the pump body at the actuation interface.
The pump of claim 1, wherein the holder comprises:

a holder shaft extending along the pump axis; and

a brace flange projecting radially outward the holder shaft beyond an exterior surface the piston shaft.
The pump of claim 2, wherein the pump body comprises:

a pump base; and

an air cylinder connected to the pump base at a first axial end of the pump base, the piston head disposed within the air cylinder to reciprocate within the air cylinder;

wherein the piston shaft extends into the pump base from the piston head.
The pump of claim 3, wherein a shelf is formed at the first axial end of the pump base and the brace flange extends radially outward to axially overlap with the shelf.
The pump of claim 4, wherein the brace flange is engaged with the shelf with the piston at an end of a downstroke to form the actuation interface and the brace flange is disengaged from the shelf with the piston at an end of an upstroke.
The pump of any one of claims 2-5, wherein the holder further comprises:

a support flange projecting radially inward from the holder shaft and towards the pump axis.
The pump of claim 6, wherein the extender includes a bearing supported on the support flange and interfacing with the piston shaft.
The pump of claim 7, wherein the limit spring interfaces with the bearing.
The pump of any one of claims 1 6, wherein the extender further comprises:

a bearing supported by the holder and interfacing with the piston shaft.
The pump of any one of claims 1-9, wherein:

the piston shaft includes a receiving chamber formed in the piston shaft, the receiving chamber open towards the piston head; and

the holder is at least partially disposed within the receiving chamber.
The pump of claim 10, wherein the holder seats on a base of the receiving chamber.
The pump of any one of claims 10 and 11, wherein the piston shaft comprises:

a connector shaft extending axially from the piston head; and

a piston rod connected to and extending axially from the connector shaft, the receiving chamber formed within the piston rod.
The pump of claim 12, wherein the holder is at least partially disposed within the receiving chamber with the piston at an end of an upstroke such that the holder radially overlaps with the connector shaft and the piston rod.
The pump of any one of claims 12 and 13, wherein the connector shaft extends fully axially through the holder.
The pump of any preceding claim, wherein the air valve comprises:

a valve cap disposed on a first axial side of the piston head, the valve cap engaged with the piston head with the air valve in the open state and disengaged from the piston head with the air valve in the closed state;

a valve base disposed on a second axial side of the piston head opposite the first axial side of the piston head, the second axial side of the piston head oriented towards the extender;

a valve connector extending through a passage and between the valve cap and the valve base; and

a passage seal supported by the valve base, the passage seal engaging the piston head to fluidly disconnect a first driving chamber at least partially defined by the first axial side of the piston head from a second driving chamber at least partially defined by the second axial side of the piston head.
The pump of claim 15, wherein the passage seal extends annularly around the connector.
A pump comprising:

a pump body;

a piston disposed within the pump body and configured to reciprocate along a pump axis, the piston including a piston head and a piston shaft;

an air valve supported by the piston, the air valve actuatable between an open state and a closed state, the air valve directing driving air to cause the piston to move through a first stroke in a first axial direction along the pump axis with the air valve in the closed state and the air valve directing the driving air to cause the piston to move through a second stroke in a second axial direction along the pump axis with the air valve in the open state;

an end spring supported by the pump body, the end spring configured to interface with the air valve to actuate the air valve from the closed state to the open state to cause the piston to change over from the first stroke to the second stroke; and

a stroke limiter supported by the piston, the stroke limiter configured to interface with the air valve to actuate the air valve from the open state to the closed state, the stroke limiter including a brace flange configured to interface with the pump body at an actuation interface to limit axial movement of the stroke limiter in the second axial direction along the pump axis, and the stroke limiter including a limit spring at least partially disposed on an opposite axial side of the brace flange from the piston head.
The pump of claim 17, wherein the stroke limiter includes a spring chamber within which the limit spring is at least partially disposed, the spring chamber extending in the second axial direction from the brace flange.
The pump of any one of claims 17 and 18, wherein the limit spring is not fully compressed with the piston at an end of the first stroke and the limit spring is not fully compressed with the piston at an end of the second stroke.
A method of pumping, the method comprising:

directing driving air to a first driving chamber by an air valve to drive a piston in a first axial direction along a pump axis by the driving air;

engaging a holder of a stroke limiter disposed about the piston with a portion of a pump body;

driving the piston in the first axial direction with the holder engaging the portion of the pump body such that the piston moves relative to the holder and compresses a limit spring within a spring chamber formed within the holder, the spring chamber extending in the first axial direction from an interface between the holder and the pump body;

actuating the air valve from an open state to a closed state by the stroke limiter interfacing with the air valve; and

directing the driving air to a second driving chamber by the air valve with the air valve in the closed state to drive the piston in a second axial direction along the pump axis opposite the first axial direction.
The method of claim 20, wherein actuating the air valve from the open state to the closed state by the stroke limiter interfacing with the air valve comprises:

engaging the air valve with a brace supported by the limit spring; and

arresting movement of the air valve along the pump axis by the brace as the piston continues to displace in the first axial direction to cause the air valve to actuate to the closed state.
The method of any one of claims 20 and 21, wherein driving the piston in the first axial direction with the holder engaging the portion of the pump body such that the piston moves relative to the holder and compresses the limit spring within the spring chamber formed within the piston comprises:

shifting the piston in the first axial direction to shift the holder axially outward from a receiving chamber formed in a piston shaft of the piston.