Pump stroke extension apparatus and method

Abstract

A pump includes a piston disposed within a pump body, the piston reciprocating along a pump axis to pump fluid. The air valve is actuated between an open state and a closed state to drive reciprocating movement of the piston. A stroke limiter is disposed around the piston and configured to interface with the air valve to actuate the air valve. The stroke limiter includes a spring chamber that at least partially positions the limiting spring on an axial side of an interface between the stroke limiter and the pump body opposite the air valve.

Description

Background Art

[0001] The present disclosure relates generally to pumps. More particularly, the present disclosure relates to pneumatic pumps.

[0002] Pneumatic pumps rely on compressed air to displace a piston along a reciprocating axis to pump. The pump may include a piston disposed within a cylinder, on which compressed air acts to cause reciprocating motion of the fluid displacer. A spring is used to open and close a path that directs compressed air to the opposite side of the piston head to drive the fluid displacer along the reciprocating axis. The spring occupies a portion of the axial length of the pump, thereby limiting the stroke length relative to the overall length of the pump itself. Summary of the invention

[0003] According to one aspect of the present disclosure, a pump comprises: a pump body; a piston, the piston is disposed in the pump body and is configured to reciprocate along the pump axis; an air valve; and a stroke limiter, the stroke limiter is supported by the piston and is configured to contact the air valve to actuate the air valve from the open state to the closed state. The piston comprises: a piston head; and a piston shaft, the piston shaft extending axially from the piston head. The air valve is supported by the piston head and can be actuated between an open state and a closed state. The stroke limiter comprises: a retainer, the retainer is disposed around the piston shaft, the retainer defines a spring chamber; a limiting spring, the limiting spring is at least partially disposed in the spring chamber and extends axially toward the piston head; and a bracket, the bracket is disposed around the piston shaft and supported by the limiting spring, the bracket being axially disposed between the retainer 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. With the stroke limiter interfacing with the pump body at the actuation interface, the limit spring is at least partially disposed on an axial side of the actuation interface opposite the piston head.

[0004] According to additional or alternative aspects of the present disclosure, a pump comprises: a pump body; a piston, the piston being arranged in the pump body and configured to reciprocate along the pump axis, the piston comprising: a piston head and a piston shaft; an air valve, the air valve being supported by the piston, the air valve being actuated between an open state and a closed state, and when the air valve is in the closed state, the air valve guides driving air to cause the piston to move through a first stroke in a first axial direction along the pump axis, and when the air valve is in the open state, the air valve guides the driving air to cause the piston to move through a second stroke in a second axial direction along the pump axis; an end spring, the end spring being supported by the pump body, the end spring The piston is actuated by the piston and is configured to interface with the air valve to actuate the air valve from the closed state to the open state, thereby causing the piston to transition from the first stroke to the second stroke; and a stroke limiter supported by the piston, the stroke limiter being configured to interface with the air valve to actuate the air valve from the open state to the closed state, the stroke limiter comprising a bracket flange configured to interface with the pump body at an actuation interface to limit axial movement of the stroke limiter along the pump axis in the second axial direction, and the stroke limiter comprising a limit spring at least partially disposed on an axial side of the bracket flange opposite to the piston head

[0005] According to another additional or alternative aspect of the present disclosure, a pumping method includes: guiding driving air to a first driving chamber through an air valve to drive a piston in a first axial direction along a pump axis through the driving air; engaging a retaining member of a stroke limiter arranged around the piston with a portion of a pump body; driving the piston in the first axial direction when the retaining member engages the portion of the pump body, so that the piston moves relative to the retaining member and compresses a limiting spring located in a spring chamber formed in the retaining member, the spring chamber extending from an interface between the retaining member and the pump body along the first axial direction; actuating the air valve from an open state to a closed state through the stroke limiter interfacing with the air valve; and guiding the driving air to a second driving chamber through the air valve when the air valve is in the closed state to drive the piston in a second axial direction opposite to the first axial direction along the pump axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1A is a cross-sectional view of the pump.

[0007] Figure 1B yes Figure 1A Magnified view of detail B.

[0008] Figure 2A is an enlarged cross-sectional view of a portion of the pump showing the pump in a first pump state.

[0009] Figure 2B yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump shown in , showing the pump in a second pump state.

[0010] Figure 2C yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump shown in , showing the pump in a third pump state.

[0011] Figure 2D yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump shown in , showing the pump in a fourth pump state. DETAILED DESCRIPTION

[0012] Figure 1A is a cross-sectional view of the pump 10 . Figure 1B yes Figure 1A An enlarged view of detail B shown in FIG. Figure 1A and 1B Will be discussed together. The pump 10 includes a pump body 12, a piston 14, an inlet valve 16, a piston valve 18, an air valve 20, an end spring 22, and a stroke limiter 24. The pump body 12 includes a cylinder 26, a pump base 28, a fluid cylinder 30, an air inlet 32, an exhaust 34, a fluid inlet 36, and a fluid outlet 38. The piston 14 includes a piston head 40, a piston shaft 42, and a piston seal 44. The piston head 40 includes a valve passage 46 and a head hole 48. The piston shaft 42 includes a connecting shaft 50 and a piston rod 52. The piston rod 52 extends between the rod ends 54a, 54b and includes a receiving chamber 56, a protrusion 58, a rod hole 60, and a cross hole 62. The connecting shaft 50 includes an axis hole 64. The air valve 20 includes a valve cover 66, a valve base 68, a valve connector 70, and a channel seal 72. The valve connector 70 includes a fastener 74 and a sleeve 76. The stroke limiter 24 includes a retainer 78, a limit spring 80, a bracket 82, and a bearing 84. The retainer 78 extends between retainer ends 86a, 86b and includes a retainer body 88, a bracket flange 90, and a support flange 92.

[0013] The pump 10 is configured to pump a fluid, such as a liquid, such as paint, from an upstream location to a downstream location. The pumped fluid enters the pump body 12 through a fluid inlet 36 and exits the pump body 12 through a fluid outlet 38 .

[0014] The pump body 12 supports other components of the pump 10. The piston 14 is disposed within the pump body 12 and is configured to reciprocate along the pump axis PA to pump fluid from the fluid inlet 36 to the fluid outlet 38. In the example shown, the pump 10 is configured as a double displacement pump in the example shown, which means that the pump 10 outputs the pumped fluid during both an upstroke in which the piston 14 is displaced in a first axial direction AD1 along the pump axis PA and a downstroke in which the piston 14 is displaced in a second axial direction AD2 along the pump axis PA.

[0015] In the example shown, the pump 10 is configured as a pneumatic pump. Driving air is provided to the pump 10 to drive the reciprocating motion of the piston 14, and the driving air is compressed air provided from an air source such as a compressor, a pressurized tank, etc. In the example shown, the driving air is provided to the pump 10 through the air inlet 32 ​​and is discharged from the pump 10 through the exhaust portion 34. The air inlet 32 ​​provides driving air to the drive chamber 104a so that the piston 14 moves through the stroke along the first axial direction AD1. The driving air flows to the drive chamber 104b so that the piston 14 is displaced through the stroke along the second axial direction AD2. When the piston 14 is displaced along the first axial direction AD1, the driving air is discharged from the pump 10. Specifically, the driving air in the drive chamber 104b flows to the exhaust chamber 108 through the exhaust passage 96 and is discharged through the exhaust portion 34.

[0016] The pump base 28 is a central portion of the pump body 12. In the example shown, during operation of the pump 10, both the drive air and the pumped fluid flow within the pump base 28. The cylinder 26 is disposed at a first axial end of the pump base 28. The cylinder 26 is mounted to the pump base 28 and at least partially defines a drive chamber 104a and a drive chamber 104b. In the example shown, a portion of the pump base 28 extends into the cylinder 26, wherein the cylinder 26 is mounted to the pump base 28. A portion of the pump base 28 within the cylinder 26 forms a shelf 100. In the example shown, the shelf 100 is formed by an axial end face of the pump body 12 oriented in the first axial direction AD1.

[0017] The fluid cylinder 30 is provided at a second axial end of the pump base 28 opposite to the cylinder 26. The fluid cylinder 30 is connected to the pump base 28. The fluid cylinder 30 at least partially defines a fluid chamber 106a and a fluid chamber 106b through which the pumped fluid flows between the fluid inlet 36 and the fluid outlet 38. The inlet valve 16 is mounted to the fluid cylinder 30. The inlet valve 16 is a check valve configured to allow the pumped fluid to enter the pump body 12 and prevent the pumped fluid from flowing backward through the fluid inlet 36.

[0018] The piston 14 is disposed in the pump body 12. The piston 14 is configured to reciprocate along the pump axis PA to pump the pumped fluid from an upstream position fluidically connected to the fluid inlet 36 to a downstream position fluidically connected to the fluid outlet 38. The piston head 40 is disposed in the cylinder 26 and the piston head 40 is acted on by the driving air to cause the reciprocating motion of the piston 14. The piston head 40 separates the drive chamber 104a from the drive chamber 104b. The piston seal 44 is supported by the piston head 40 and engages the inner wall of the cylinder 26 to form an airtight seal between the piston head 40 and the cylinder 26.

[0019] The head hole 48 extends completely through the piston head 40. The head hole 48 is aligned on the pump axis PA. The head hole 48 forms a part of the exhaust passage 96 passing through the piston 14. The valve passage 46 extends completely through the piston head 40. The valve passage 46 is radially offset from the pump axis PA. It should be understood that the piston head 40 may include an array of valve passages 46 arranged annularly around the pump axis PA. The valve passage 46 provides a flow path for driving air to flow from the drive chamber 104a to the drive chamber 104b, so that the driving air can act on the piston head 40, so that the piston 14 is displaced through the stroke along the second axial direction AD2. Both the head hole 48 and the valve passage 46 define a flow path for driving air to flow through the piston head 40.

[0020] The piston shaft 42 extends axially from the piston head 40. The piston shaft 42 extends from the piston head 40 in the second axial direction AD2. The piston shaft 42 is connected to the piston head 40 and reciprocates with the piston head 40. The piston shaft 42 is connected to the piston head 40 at a position within the cylinder 26, extends through the pump base 28, and extends into the fluid cylinder 30. The piston shaft 42 extends from the piston head 40, passes through the drive chamber 104a, passes through the exhaust chamber 108, and enters the fluid chamber 106b.

[0021] The piston shaft 42 engages with shaft seals 98a and 98b supported by the pump body 12. The shaft seals 98a, 98b are configured as dynamic seals so that the components move relative to the shaft seals 98a, 98b during operation. In the example shown, the shaft seals 98a, 98b are supported by the pump body 12, and the piston 14 reciprocates relative to the shaft seals 98a, 98b. An exhaust chamber 108 is formed axially between the shaft seals 98a, 98b. The exhaust portion 34 is a port through the pump body 12 that is in fluid communication with the exhaust chamber 108.

[0022] Exhaust passage 96 is formed through piston 14 and is configured to provide a flow path for driving air to be exhausted from drive chamber 104b. Transverse hole 62 extends into piston shaft 42 and intersects exhaust passage 96. Transverse hole 62 extends from the outside of piston shaft 42 to exhaust passage 96. Transverse hole 62 provides a flow path for driving air to leave from piston 14 and enter exhaust chamber 108 formed in pump body 12.

[0023] The piston shaft 42 includes a connecting shaft 50 connected to and extending from the piston head 40, and the piston shaft 42 includes a piston rod 52 connected to the connecting shaft 50 and extending from the connecting shaft 50. The connecting shaft 50 can be connected to one or both of the piston head 40 and the piston rod 52 by interface threads therebetween. The shaft hole 64 extends axially through the connecting shaft 50. The shaft hole 64 defines a portion of the exhaust passage 96 passing through the piston 14. The shaft hole 64 provides a flow path for driving air to flow from the head hole 48 to the rod hole 60.

[0024] The piston rod 52 is connected to the connecting shaft 50 and extends axially from the connecting shaft 50. The connecting shaft 50 extends into the piston rod 52 and is directly connected to the piston rod 52. The connecting shaft 50 can be connected to the piston rod 52 in any desired manner, such as by an interface thread. The piston rod 52 engages with the shaft seals 98a, 98b to fluidly isolate the exhaust chamber 108 from the drive chamber 104a and to fluidly isolate the exhaust chamber 108 from the fluid chamber 106b. The rod seal 102 is disposed between the connecting shaft 50 and the piston rod 52 in the rod hole 60. The rod seal 102 can be formed as an elastomeric seal, such as an O-ring, etc.

[0025] The rod end 54a is an axial end of the piston rod 52 oriented toward the piston head 40. The rod end 54a is oriented in a first axial direction AD1. The rod end 54b is an axial end of the piston rod 52 opposite to the rod end 54a. The rod end 54b is oriented toward the inlet valve 16. The rod end 54b is oriented in a second axial direction AD2. The rod hole 60 extends from the rod end 54a into the piston rod 52. The rod hole 60 extends axially in the piston rod 52. The rod hole 60 forms a portion of the exhaust passage 96 that passes through the piston 14.

[0026] The piston valve 18 is provided at the axial end of the piston shaft 42 opposite to the piston head 40. The piston valve 18 is mounted to the piston shaft 42. More specifically, the piston valve 18 is mounted to the piston rod 52 at the rod end 54b. The piston valve 18 is carried by the piston shaft 42 to reciprocate with the piston 14. The piston valve 18 carries a seal that engages with the inner surface of the fluid cylinder 30. The piston valve 18 divides the fluid chamber within the pump 10 into an upstream fluid chamber 106a and a downstream fluid chamber 106b, through which the pumped fluid flows.

[0027] The air valve 20 is supported by the piston 14. In the example shown, the air valve 20 is supported by the piston head 40. The air valve 20 is mounted on the piston head 40 so that the air valve 20 and the piston head 40 travel axially along the pump axis PA. As discussed in more detail below, the air valve 20 can move relative to the piston head 40 to open and close the flow path of the valve passage 46 between the drive chamber 104a and the drive chamber 104b. The air valve 20 can be actuated between a first valve state and a second valve state, in which the drive air can flow from the drive chamber 104a to the drive chamber 104b through the valve passage 46, and in which the drive air is prevented from flowing through the valve passage 46 between the drive chamber 104a and the drive chamber 104b. The first valve state may also be referred to as an open state. The second valve state may also be referred to as a closed state. The air valve 20 directs drive air to move the piston 14 through a stroke in the first axial direction AD1 when the air valve 20 is in a closed state, and directs drive air to move the piston 14 through a stroke in the second axial direction AD2 when the air valve 20 is in an open state.

[0028] The valve cover 66 is disposed on a first axial side of the piston head 40. The valve cover 66 is disposed on a side of the piston head 40 oriented in the first axial direction AD1 and facing the end spring 22. The valve cover 66 is disposed above the head hole 48 passing through the piston head 40 and is axially aligned with the head hole 48. The valve cover 66 is configured to engage with the piston head 40 to seal the flow path through the head hole 48 when the driving air is provided to the drive chamber 104b to drive the piston 14 in the second axial direction AD2. The valve cover 66 is configured to be disengaged from the piston head 40 to open the flow path through the head hole 48 when the driving air is provided to the drive chamber 104a to drive the piston 14 in the first axial direction AD1. The valve cover 66 disengaged from the piston head 40 fluidly connects the drive chamber 104b with the exhaust portion 34 via the exhaust passage 96, the cross hole 62 and the exhaust chamber 108.

[0029] The valve base 68 is provided on a second axial side of the piston head 40 opposite to the first axial side of the piston head 40. The valve base 68 is provided on a side of the piston head 40 oriented in the second axial direction AD2 and facing the stroke limiter 24. The valve base 68 is provided on an axial side of the piston head 40 opposite to the valve cover 66.

[0030] A passage seal 72 is supported on the valve base 68. The passage seal 72 is axially disposed between the valve base 68 and the piston head 40. The passage seal 72 is configured to interface with the piston head 40 to fluidly disconnect the valve passage 46 from the drive chamber 104a when the air valve 20 is in the second valve state. The passage seal 72 is configured to disengage from the piston head 40 to fluidly connect the drive chambers 104a, 104b via the valve passage 46 when the air valve 20 is in the first valve state.

[0031] The valve connector 70 extends between the valve cover 66 and the valve base 68 and connects the valve cover 66 and the valve base 68. The valve connector 70 extends through the valve passage 46 formed in the piston head 40. The valve connector 70 can be directly connected to one or both of the valve cover 66 and the valve base 68. In the example shown, the valve connector 70 is formed by a fastener 74 (such as a bolt) that connects the valve base 68 and the valve cover 66 and a sleeve 76 that axially fixes the valve base 68 relative to the valve cover 66. The fastener 74 extends through the valve base 68 and is directly connected to the valve cover 66. The head of the valve connector 70 is the head of the fastener 74 in the example shown, and the head of the valve connector 70 is larger than the hole in the valve base 68 through which the valve connector 70 extends. The head of the valve connector 70 that interfaces with the valve base 68 prevents the valve base 68 from shifting in the second axial direction AD2 and leaving the valve connector 70. The valve connector 70 connects the valve cover 66 and the valve base 68 to move simultaneously when the air valve 20 is switched between the first valve state and the second valve state. In the example shown, the air valve 20 includes a plurality of valve connectors 70 extending between the valve cover 66 and the valve base 68 and connecting the valve cover 66 and the valve base 68. It should be understood that the air valve 20 may include one, two, three, four or more valve connectors 70. Therefore, the piston head 40 may include a plurality of one or more valve passages 46 passing through the piston head 40. Each valve connector 70 includes an associated passage seal 72. The passage seal 72 extends annularly around the valve connector 70.

[0032] The end spring 22 is disposed within the cylinder 26. The end spring 22 is disposed on the axial side of the piston head 40 opposite to the piston rod 52. The end spring 22 is disposed on the axial side of the piston head 40 opposite to the stroke limiter 24. The end spring 22 is supported by the pump body 12. In the example shown, the end spring 22 is mounted to the cylinder 26. The end spring 22 is mounted to the pump body 12 so that the piston 14 can move away from the end spring 22 when the piston 14 is displaced in the second axial direction AD2, and so that the piston 14 can move toward the end spring 22 when the piston 14 moves in the first axial direction AD1. The end spring 22 is configured to interface with the air valve 20 at the end of the upward stroke in the first axial direction AD1. The end spring 22 is configured to interface with the air valve 20 to actuate the air valve 20 from the second valve state to the first valve state. Specifically, the end spring 22 is configured to interface with the valve cover 66 to switch the air valve 20 from the second valve state to the first valve state.

[0033] In the example shown, the piston shaft 42 includes a receiving chamber 56 formed in the piston shaft 42. Specifically, the receiving chamber 56 is formed in the piston rod 52. The receiving chamber 56 is axially open toward the piston head 40. The receiving chamber 56 is axially spaced from the piston head 40. The protrusion 58 is a portion of the piston rod 52 extending to the rod end 54a. The protrusion 58 may be a cylindrical protrusion extending from the main body portion of the piston rod 52 along the first axial direction AD1. The receiving chamber 56 extends from the rod end 54a into the main body of the piston rod 52. The protrusion 58 defines the radially outer portion of the receiving chamber 56. The receiving chamber 56 may be formed as a portion of the rod hole 60 passing through the piston rod 52. The receiving chamber 56 has a larger diameter than other portions of the rod hole 60. In the example shown, the receiving chamber 56 is the largest diameter portion of the rod hole 60. The diameter of the receiving chamber 56 is larger than the outer diameter of the connecting shaft 50. Although the piston 14 is shown to include a receiving chamber 56 into which the retainer 78 extends during at least a portion of the operation of the pump 10, it should be understood that not all examples are limited thereto. In some examples, the piston rod 52 does not include a cylindrical protrusion 58 that protrudes axially to define the receiving chamber 56.

[0034] The stroke limiter 24 is supported by the piston 14. The stroke limiter 24 is disposed around the piston 14 and is disposed coaxially with the piston 14. The stroke limiter 24 is supported by the piston 14 but is disconnected from the piston 14. Therefore, the piston 14 can move axially relative to the stroke limiter 24, as discussed in more detail below.

[0035] The stroke limiter 24 is configured to limit the travel limit of the piston 14 through the downward stroke along the second axial direction AD2. Because the stroke limiter 24 helps to achieve a longer stroke length relative to previous pump designs, the stroke limiter 24 may also be referred to as a stroke extender. The stroke limiter 24 is configured to interface with the air valve 20 at the end of the downward stroke along the second axial direction AD2S. The stroke limiter 24 actuates the air valve 20 from the first valve state to the second valve state. Specifically, the stroke limiter 24 is configured to interface with the valve base 68 to convert the air valve 20 from the first valve state to the second valve state. The stroke length of the piston 14 is the linear distance that the piston 14 travels along the pump axis PA, through the stroke of the piston 14 along any one of the first axial direction AD1 and the second axial direction AD2, and is defined between.

[0036] The stroke limiter 24 is configured to, during a portion of the stroke of the piston 14, at the actuation interface 110 (at Figures 2B to 2D In the example shown, the actuation interface 110 is formed between the bracket flange 90 and the shelf 100. The stroke limiter 24 interfaces with the pump body 12 to limit movement of the stroke limiter in the second axial direction AD2 along the pump axis PA.

[0037] The retainer 78 extends axially between the retainer end 86a and the retainer end 86b. The retainer end 86a is axially oriented toward the piston head 40. The retainer end 86b is axially oriented away from the piston head 40. The retainer ends 86a, 86b may also be referred to as axial ends of the retainer 78. A spring chamber 94 is formed in the retainer 78. Specifically, the spring chamber 94 is radially arranged in the retainer body 88. The spring chamber 94 may be a cylindrical chamber extending completely annularly around the pump axis PA. The spring chamber 94 is formed around the connecting shaft 50 and is arranged in the retainer body 88. The spring chamber 94 extends axially between the retainer ends 86a, 86b. The spring chamber 94 is configured to receive at least a portion of the limiting spring 80 during operation of the pump 10. The spring chamber 94 is open toward the piston head 40 along the first axial direction AD1 so that the limiting spring 80 can extend through the open end of the spring chamber 94.

[0038] The retainer 78 is disposed around the piston shaft 42 so that the piston shaft 42 extends completely axially through the retainer 78. The piston shaft 42 protrudes axially outward from both the retainer end 86a and the retainer end 86b. Specifically, the retainer 78 is disposed around the connecting shaft 50, and the connecting shaft 50 extends completely axially through the retainer 78 and protrudes through both the retainer end 86a and the retainer end 86b.

[0039] The support flange 90 extends radially from the retainer body 88. In the example shown, the support flange 90 is disposed at the retainer end 86a. The support flange 90 is disposed at the end of the retainer body 88 oriented along the first axial direction AD1 and toward the piston head 40. The support flange 90 extends radially outward from the retainer body 88 in a manner away from the pump axis PA. The support flange 90 can extend completely annularly around the pump axis PA. The support flange 90 extends radially from the retainer body 88 and extends outward beyond the outside of the piston rod 52. The support flange 90 has a larger diameter than the outside of the portion of the piston rod 52 at the rod end 54a. The support flange 90 has a larger diameter than the outside of the portion of the piston rod 52 that defines the receiving chamber 56. In some examples, the support flange 90 has a larger diameter than any portion of the piston rod 52. The support flange 90 extends radially outward and partially spans the radial gap between the outer surface of the piston rod 52 and the inner surface of the cylinder 26.

[0040] The bracket flange 90 extends radially from the retainer body 88 to axially overlap with the portion of the pump body 12 that forms the shelf 100. When the components are arranged to be at a common radial position relative to the axis, the components can be considered to overlap each other axially so that an axial straight line parallel to the axis extends through each of those axially overlapping components. The bracket flange 90 is configured to contact the shelf 100 of the pump body 12 to prevent movement of the retainer 78 along the second axial direction AD2, as discussed in more detail below. In the example shown, an actuation interface 110 is formed between the bracket flange 90 and the shelf 100.

[0041] The support flange 92 defines a closed end of the spring chamber 94. Although the hole extends through the retainer 78 to allow the piston shaft 42 to pass completely through the retainer 78, the spring chamber 94 is considered to be closed because the support flange 92 extends radially inward to prevent the limit spring 80 from axially moving out of the spring chamber 94 along the second axial direction AD2. The support flange 92 is configured to support the limit spring 80. The support flange 92 is provided at the retainer end 86b opposite to the axial end of the retainer 78 where the support flange 90 is provided. The support flange 92 extends radially inward from the retainer body 88 and toward the pump axis PA. The support flange 92 can be completely annularly arranged around the pump axis PA. In the example shown, the support flange 92 extends radially inward toward the connecting shaft 50, but does not contact the connecting shaft 50. The support flange 92 is radially spaced from the connecting shaft 50 to inhibit wear caused by direct contact and relative movement between the support flange 92 and the connecting shaft 50.

[0042] In the example shown, the retainer 78 is configured to be at least partially disposed within the piston 14 during at least a portion of the stroke of the piston 14. Specifically, the retainer 78 is configured to be at least partially disposed within the receiving chamber 56 formed in the piston rod 52 during at least a portion of the stroke of the piston 14. However, it should be understood that not all examples are limited to this.

[0043] The limit spring 80 is arranged around the connecting shaft 50. The limit spring 80 is axially arranged between the support flange 92 and the piston head 40. The limit spring 80 is configured to bias the bracket 82 in the first axial direction AD1. The limit spring 80 is coaxially arranged on the pump axis PA with the piston 14. The limit spring 80 is at least partially arranged in a spring chamber 94 formed in the retainer 78. When the limit spring 80 is extended, the limit spring 80 protrudes axially outward from both axial sides of the bracket flange 90. The limit spring 80 extends away from the bracket flange 90 in the first axial direction AD1. The limit spring 80 extends away from the bracket flange 90 in the second axial direction AD2.

[0044] The limit spring 80 extending away from the bracket flange 90 in the second axial direction AD2 places at least a portion of the limit spring 80 on the axial side of the bracket flange 90 opposite the piston head 40. Disposing the limit spring 80 at least on the axial side of the bracket flange 90 opposite the piston head 40 helps to at least partially dispose the limit spring 80 on the axial side of the actuation interface 110 opposite the piston head 40. Disposing the limit spring 80 on the axial side of the actuation interface 110 opposite the piston head 40 helps to increase the stroke length of the piston 14, as discussed in more detail below.

[0045] The bracket 82 is supported by the limit spring 80. The bracket 82 is arranged around the connecting shaft 50. The bracket 82 is configured to float relative to the connecting shaft 50 and is not directly connected to the connecting shaft 50. The bracket 82 can be formed as a ring or a washer, etc. The bracket 82 can extend completely annularly around the pump axis PA. In the example shown, the bracket 82 forms a part of the stroke limiter 24 configured to interface with the valve base 68 to actuate the air valve 20 to the second closed state.

[0046] The bearing 84 is disposed at an axial end of the limit spring 80 opposite to the bracket 82. The bearing 84 is disposed within the spring chamber 94. The bearing 84 is axially disposed between the limit spring 80 and the support flange 92. In the example shown, the bearing 84 is supported on the support flange 92. Thus, the support flange 92 can be considered to indirectly support the limit spring 80 via the bearing 84. The bearing 84 interfaces with the piston shaft 42 on the radial inner side of the bearing 84 and interfaces with the retainer 78 on the radial outer side of the bearing 84. In the example shown, the bearing 84 is the only component of the stroke limiter 24 that directly interfaces with the connecting shaft 50, but it should be understood that not all examples are limited to this. In the example shown, the bearing 84 is configured as a linear bearing that slides along the connecting shaft 50 when the piston 14 is axially displaced relative to the stroke limiter 24.

[0047] Figure 2A is an enlarged cross-sectional view of a portion of the pump 10 showing the pump 10 in a first pump state. Figure 2B yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump 10 shown in , illustrating the pump 10 in a second pump state. Figure 2C yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump 10 shown in , illustrating the pump 10 in a third pump state. Figure 2D yes Figure 2A 0 is an enlarged cross-sectional view of a portion of the pump 10 shown in , showing the pump 10 in a fourth pump state. FIG. 2A to FIG. 2D Will be discussed together and continue to refer to Figure 1A and Figure 1B .

[0048] FIG. 2A to FIG. 2D The pump 10 is shown transitioning through a downstroke and then transitioning through an upstroke. During operation, the piston 14 is configured to pump the pumped fluid by reciprocating in an upstroke in a first axial direction AD1 and a downstroke in a second axial direction AD2. An example of a pump cycle including both an upstroke and a downstroke is briefly discussed below. In the example discussed, the piston 14 is at the end of the upstroke and begins a downstroke.

[0049] Drive air is provided to the pump 10 through the air inlet 32. For example, a compressed air source (e.g., an air compressor, a pressurized tank, etc.) is connected to the air inlet 32 ​​through a hose and fittings. The drive air initially flows into the drive chamber 104a. Figure 2A In the embodiment, the pump 10 is in the first pump state after the transition from the upstroke to the start of the downstroke. Figure 2AAs shown, the end spring 22 has actuated the air valve 20 to the first valve state, so that the channel seal 72 is disengaged from the piston head 40, and the valve cover 66 is engaged with the piston head 40. The valve channel 46 is opened to fluidly connect the drive chamber 104a with the drive chamber 104b. The driving air flows into the drive chamber 104a, passes through the valve channel 46, and flows into the drive chamber 104b. The driving air acts on the piston head 40 and drives the piston 14 in the second axial direction AD2, thereby increasing the volume of the drive chamber 104b and reducing the volume of the drive chamber 104a.

[0050] Moving the piston 14 in the second axial direction AD2 displaces the piston valve 18 to an open state and displaces the inlet valve 16 to a closed state. Fluid in the fluid chamber 106a can flow through the piston valve 18, into the fluid chamber 106b, and out of the pump 10 downstream through the fluid outlet 38. The piston 14 is displaced in the second axial direction AD2, and the pump 10 is placed in Figure 2B During the downward stroke of the piston 14 and before the piston 14 transitions to the upward stroke, the pump 10 is placed in the second state. Figure 2B As shown, the bracket flange 90 touches a shelf 100 formed by the axial end surface of the pump body 12. The bracket flange 90 interfaces with the shelf 100 to form an actuation interface 110 between the stroke limiter 24 and the pump body 12. The actuation interface 110 prevents further movement of the retainer 78 in the second axial direction AD2. When the actuation interface 110 prevents further displacement of the retainer 78 in the second axial direction AD2, the piston 14 continues to displace in the second axial direction AD2. The piston 14 moves in the second axial direction AD2 relative to the stroke limiter 24.

[0051] The piston 14 continues to shift in the second axial direction AD2 to move the pump 10 from Figure 2B The second pump state shown in FIG. Figure 2C The third pump state is shown in FIG. The piston 14 moves relative to the retainer 78 , and the bearing 84 slides along the outside of the connecting shaft 50 . The piston 14 continues to travel in the second axial direction AD2 , and the valve base 68 touches the bracket 82 .

[0052] With the bracket flange 90 supported on the shelf 100 and the valve base 68 engaging the bracket 82, the piston 14 continues to travel in the second axial direction AD2 to compress the limit spring 80 between the bracket 82 and the retainer 78. Specifically, the limit spring 80 is compressed between the bracket 82 and the bearing 84. Since the valve base 68 drives the bracket 82 in the second axial direction AD2 and the bracket 82 acts on the limit spring 80 in the second axial direction AD2, the limit spring 80 is compressed into the spring chamber 94. The limit spring 80 is disposed on the axial side of the actuation interface 110 opposite to the piston head 40. Since the limit spring 80 is compressed into the spring chamber 94, the portion of the limit spring 80 disposed on the axial side of the bracket flange 90 opposite to the piston head 40 increases.

[0053] The piston 14 continues to displace the bracket 82 in the second axial direction AD2 and compresses the limit spring 80 into the spring chamber 94 until the bracket 82 touches the retainer 78. The retainer 78 provides a hard stop that prevents the bracket 82 from further displacement in the second axial direction AD2. The bracket 82 is seated on the retainer 78 at the retainer end 86a. The retainer 78 is prevented from further displacement in the second axial direction AD2 by the actuation interface 110, and the bracket 82 is prevented from further displacement in the second axial direction AD2 by the retainer 78.

[0054] With the bracket 82 engaged with the retainer 78, the limit spring 80 is at a maximum operating compression. With the bracket 82 engaged with the retainer 78, the limit spring 80 cannot be further compressed. It should be understood that the maximum operating compression may not be the maximum spring compression of the limit spring 80. The maximum spring compression occurs when the limit spring 80 is fully compressed, which would occur if the retainer 78 did not engage the bracket to prevent the bracket 82 from continuing to drive the limit spring 80 into the spring chamber 94. Thus, the limit spring 80 is not fully compressed within the spring chamber 94. The maximum operating compression being less than the maximum spring compression prevents undesirable wear on the limit spring 80, increases the operating life of the limit spring 80, reduces downtime of the pump 10, and reduces maintenance requirements and costs.

[0055] The stroke limiter 24 interfaces with the valve base 68 and acts as a stopper to prevent the valve base 68 from further moving in the second axial direction AD2. The stroke limiter 24 abuts against the valve base 68, so that the air valve 20 is actuated to the second valve state. The piston 14 continues to travel in the second axial direction AD2 and moves relative to the air valve 20 and the stroke limiter 24. Since the bracket 82 interfaces with the valve base 68, the air valve 20 is prevented from shifting along the second axial direction AD2 with the piston head 40. The piston 14 moving in the second axial direction AD2 relative to the valve base 68 engages the channel seal 72 with the piston head 40 to seal the flow path through the valve channel 46. Therefore, the drive chamber 104a is fluidly isolated from the drive chamber 104b. Since the valve base 68 and the valve cover 66 are connected by the valve connector 70, the valve cover 66 is lifted away from the piston head 40. Lifting the valve cover 66 away from the piston head 40 fluidly connects the drive chamber 104b with the exhaust passage 96. Thus, the pump 10 switches to Figure 2C The third pump state shown in .

[0056] The third pump state is associated with the transition of the piston 14 from a downward stroke in the second axial direction AD2 to an upward stroke in the first axial direction AD1. At the time of the transition, the limit spring 80 is completely disposed within the spring chamber 94. As shown, at the transition from the downward stroke to the upward stroke, the limit spring 80 is completely disposed outside the receiving chamber 56, but it should be understood that not all examples are limited to this. Although the limit spring 80 is completely disposed in the spring chamber 94, it should be understood that the limit spring 80 may not be fully compressed to the maximum spring compression. The size of the limit spring 80 can be designed so that even if the bracket 82 interfaces with the retaining member 78, the limit spring 80 is not fully compressed.

[0057] The limit spring 80 is at least partially disposed on an axial side of the actuation interface 110 opposite to the interface between the stroke limiter 24 and the air valve 20. The limit spring 80 extends to radially overlap a portion of the pump body 12 disposed on an axial side of the actuation interface 110 opposite to the piston head 40. The components can be considered to radially overlap each other when they are disposed at a common axial position along an axis such that a radial line extending from the axis extends through each of those radially overlapping components. The limit spring 80 axially extending beyond the actuation interface 110 in the same axial direction as the piston 14 displaces during the downstroke facilitates a longer stroke length of the pump 10. The axial end of the limit spring 80 oriented toward the piston head 40 and extending axially toward the piston head 40 relative to the actuation interface 110 will otherwise define the axial stroke length. The extension spring will be fully compressed, and the position of this end of the extension spring along the pump axis PA will define the limit of movement of the piston 14 by actuating the air valve 20 to the first valve state. Retracting the limit spring 80 on the axial side of the actuation interface 110 opposite the piston head 40 helps the piston head 40 travel further in the second axial direction AD2 before the air valve 20 is actuated, thereby increasing the stroke length relative to prior art pumps.

[0058] When the air valve 20 is in the closed state, the driving air is prevented from flowing from the driving chamber 104a to the driving chamber 104b. The driving air in the driving chamber 104a acts on the piston head 40 and displaces the piston 14 in the first axial direction AD1. The limiting spring 80 applies a driving force to the bracket 82 in the first axial direction AD1. Therefore, the limiting spring 80 applies a driving force to the piston 14 in the first axial direction AD1 through the bracket 82 and the valve base 68.

[0059] The limit spring 80 assists the piston 14 in transitioning from the downstroke to the upstroke. The piston 14 is stationary at the transition point between the downstroke and the upstroke. The limit spring 80, which applies a biasing force in the first axial direction AD1, prevents the pump 10 from stalling or stopping at the transition point. The limit spring 80 helps overcome the fluid resistance in the fluid chamber 106b that acts on the piston 14 to resist movement in the first axial direction AD1, and helps accelerate the piston 14 out of the transition toward the upstroke.

[0060] When the piston 14 is displaced in the first axial direction AD1 through the upstroke, the piston valve 18 is displaced to a closed state, thereby reducing the volume of the fluid chamber 106b and increasing the volume of the fluid chamber 106a. The pumped fluid is driven downstream of the fluid chamber 106b through the fluid outlet 38. The piston 14 displaced in the first axial direction AD1 causes the inlet valve 16 to open, and the pumped fluid is sucked into the fluid chamber 106a.

[0061] The piston 14 begins to move through the upward stroke in the first axial direction AD1. As the volume of the drive chamber 104b decreases, the drive air contained in the drive chamber 104b is driven into the exhaust passage 96 and reaches the cross hole 62 through the exhaust passage 96. The drive air leaves the piston 14 through the cross hole 62 and flows into the exhaust chamber 108. The drive air is exhausted from the pump 10 through the exhaust portion 34 fluidly connected to the exhaust chamber 108.

[0062] The limit spring 80 extends and pushes the bracket 82 in the first axial direction AD1 and away from the retainer 78. When the piston 14 moves in the first axial direction AD1 relative to the retainer 78, the retainer 78 initially remains seated on the shelf 100. The piston 14 moves in the first axial direction AD1, and the pump 10 switches to the fourth pump state, which occurs during the upward stroke of the piston 14 and before the piston 14 transitions to the downward stroke. The piston shaft 42 is displaced relative to the retainer 78, and the retainer 78 is displaced into the receiving chamber 56 through the open end of the receiving chamber 56. The axial clearance between the rod end 54a and the bracket flange 90 is reduced.

[0063] The piston 14 continues to shift in the first axial direction AD1, and the retainer 78 is seated on the piston shaft 42. In the example shown, the retainer body 88 enters the receiving chamber 56. A portion of the piston 14 (e.g., the piston rod 52 and / or the connecting shaft 50) engages with the retainer 78 and carries the retainer 78 in the first axial direction AD1. In some examples, the retainer end 86b engages with the base of the receiving chamber 56 to seat the retainer 78 on the piston shaft 42. In some examples, the retainer 78 can be considered to bottom out in the receiving chamber 56. The piston shaft 42 can apply a driving force to the retainer 78 at the interface between the retainer 78 and the piston shaft 42 within the receiving chamber 56. In some examples, the rod end 54a engages the bracket flange 90 to apply a driving force to the retainer 78 in the first axial direction AD1. In other examples, when the retainer 78 bottoms out in the receiving chamber 56, the rod end 54a is axially spaced from the bracket flange 90. Disengaging the rod end 54 a from the bracket flange 90 while the piston 14 displaces the retainer 78 in the first axial direction AD1 prevents deformation and damage to the bracket flange 90 , thereby increasing the operating life of the stroke limiter 24 .

[0064] The piston 14 continues to travel axially in the first axial direction AD1 toward the end spring 22. The retainer 78 engages with the piston shaft 42 and is carried in the first axial direction AD1, causing the bracket flange 90 to disengage from the shelf 100. The piston 14 continues to travel to transition through the upstroke and touches the end spring 22, which actuates the air valve 20 to the open state. The passage seal 72 disengages from the piston head 40, and the drive chamber 104a is fluidly connected to the drive chamber 104b again. The valve cover 66 engages the piston head 40 to fluidly disconnect the drive chamber 104b and the exhaust passage 96. The piston 14 transitions from the upstroke to the downstroke, and the pump 10 is again in the Figure 2A The first pump state is shown. The piston 14 continues to reciprocate between the respective upstroke and downstroke.

[0065] During part of the operation of the pump 10, the retainer 78 is at least partially disposed within the receiving chamber 56 of the piston shaft 42. The retainer 78 extends into the receiving chamber 56 so that parts of the piston shaft 42 are disposed on both radial sides of the retainer 78. The retainer 78 radially overlaps the connecting shaft 50 and the piston rod 52. The retainer 78 is disposed in the receiving chamber 56 so that a radial line extending from the pump axis PA first passes through the connecting shaft 50, then through the retainer 78, and then through the piston rod 52.

[0066] During other portions of the operation of the pump 10, the retainer 78 is disposed axially outside of the receiving chamber 56. The shelf 100 abuts against the bracket flange 90, and the retainer 78 is at least partially moved out of the receiving chamber 56 so that portions of the retainer body 88 do not radially overlap the piston rod 52. The axial length of the retainer 78 that radially overlaps the piston rod 52 varies during the reciprocating motion of the piston 14.

[0067] The limit spring 80 extends into the spring chamber 94 and is disposed on the axial side of the hard stop formed at the actuation interface 110 opposite to the interface between the stroke limiter 24 and the air valve 20 that actuates the air valve 20 to the closed state. The limit spring 80 extends to radially overlap a portion of the pump body 12 disposed on the axial side of the actuation interface 110 opposite to the piston head 40 (particularly a portion of the pump base 28). This configuration forms a pump 10 having a longer stroke length relative to previous pumps without correspondingly increasing the axial length of the pump 10 itself.

[0068] During a portion of the operation of the pump 10, the limit spring 80 extends axially outwardly in a first axial direction AD1 relative to the component of the stroke limiter 24 that forms the actuation interface 110 (in the illustrated example, the bracket flange 90) and toward the piston head 40. During a portion of the stroke of the piston 14, the limit spring 80 is retracted into the spring chamber 94 and then extends axially out of the spring chamber 94, which helps the limit spring 80 assist the piston 14 in transitioning to the upstroke while also helping the piston 14 pump at an increased pump stroke length.

[0069] The pump 10 and the stroke limiter 24 provide significant advantages. The stroke limiter 24 is separated or disconnected from the piston 14 so that the piston 14 can move relative to the stroke limiter 24. When the piston 14 moves through the downstroke, the limit spring 80 is received in the spring chamber 94. Receiving the limit spring 80 in the spring chamber 94 increases the stroke length of the piston 14 without any associated change in the axial length of the pump 10 itself, wherein the spring chamber 94 protrudes in the second axial direction AD2 relative to the bracket flange 90 that limits the axial movement of the retainer 78 in the second axial direction AD2. Therefore, the stroke limiter 24 allows a greater stroke length, and therefore allows a greater fluid displacement during the stroke, without a corresponding increase in the length of the pump body 12. Therefore, the pump 10 can discharge a larger volume of fluid with a more compact pump body 12, thereby facilitating installation in a constrained or limited area. Therefore, the pump 10 can output a larger volume of pumped fluid with fewer transitions. The piston 14 stops moving at the transition and must accelerate away from the transition. Reducing the number of shifts reduces wear on the components of the pump 10, thereby reducing maintenance costs and downtime.

[0070] The limit spring 80 is received in the spring chamber 94. In some examples, the limit spring 80 is not fully compressed in the spring chamber 94. Compressing the limit spring 80 to less than a fully compressed amount reduces wear on the limit spring 80, thereby increasing the life of the limit spring 80 and requiring less downtime and maintenance of the pump 10. The limit spring 80 also helps drive the piston 14 in the first axial direction AD1 and move the piston 14 out of transition, thereby preventing stalling or stalling of the pump 10.

[0071] The limit spring 80 also provides cushioning for the piston 14 during the process of the piston 14 transitioning from the downstroke to the upstroke. The air valve 20 transitions from the open state to the closed state, and then the piston 14 begins to decelerate until the piston 14 stops moving at the transition point. The limit spring 80 can act as a damper that helps to decelerate the piston 14 and minimize the impact between the components, thereby minimizing the vibration of the pump 10. Therefore, the limit spring 80 can also reduce the noise of the pump 10 during operation.

[0072] Although the present invention has been described with reference to (multiple) exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements of the exemplary embodiments without departing from the scope of the present invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present invention without departing from the basic scope of the present invention. Therefore, it is intended that the present invention not be limited to the specific (multiple) embodiments disclosed, but that the present invention will include all embodiments falling within the scope of the appended claims.

Claims

1. A pump comprising: Pump body; A piston is disposed in the pump body and is configured to reciprocate along a pump axis, the piston comprising: piston head; and a piston shaft extending axially from the piston head; an air valve supported by the piston head, the air valve being 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 retainer disposed around the piston shaft, the retainer defining a spring chamber; a limit spring at least partially disposed within the spring chamber and extending axially toward the piston head; and a bracket, the bracket being arranged to surround the piston shaft and supported by the limiting spring, the bracket being axially arranged between the retaining member 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, with the stroke limiter interfacing with the pump body at the actuation interface, the limit spring is at least partially disposed on an axial side of the actuation interface opposite the piston head.

2. The pump according to claim 1, wherein The retaining member comprises: a retaining shaft extending along the pump axis; and A bracket flange protrudes radially outward from the retaining shaft beyond an outer surface of the piston shaft.

3. The pump according to claim 2, wherein: The pump body comprises: a pump base; and a cylinder connected to the pump base at a first axial end of the pump base, the piston head being disposed within the cylinder for reciprocating movement within the cylinder; Wherein, the piston shaft extends from the piston head into the pump base.

4. The pump according to claim 3, wherein: A shelf is formed at a first axial end of the pump base, and the bracket flange extends radially outward to axially overlap the shelf.

5. The pump according to claim 4, wherein With the piston at the end of a downstroke, the bracket flange engages the shelf to form the actuation interface, and with the piston at the end of an upstroke, the bracket flange disengages from the shelf.

6. A pump according to any one of claims 2 to 5, wherein The retaining member further comprises: A support flange projects radially inwardly from the retaining shaft and toward the pump axis.

7. The pump according to claim 6, wherein The extender includes a bearing supported on the support flange and interfacing with the piston shaft.

8. The pump according to claim 7, wherein The limit spring interfaces with the bearing.

9. The pump according to any one of claims 1 to 6, wherein The extender also includes: A bearing is supported by the retainer and interfaces with the piston shaft.

10. A pump according to any one of claims 1 to 9, wherein: The piston shaft includes a receiving chamber formed therein, the receiving chamber opening toward the piston head; and The retaining member is at least partially disposed within the receiving chamber.

11. The pump according to claim 10, wherein The retaining member is placed on a base of the receiving chamber.

12. A pump according to any one of claims 10 and 11, wherein The piston shaft comprises: a connecting shaft extending axially from the piston head; and A piston rod is connected to the connecting shaft and extends axially from the connecting shaft, and the receiving chamber is formed in the piston rod.

13. The pump according to claim 12, wherein With the piston at the end of an upward stroke, the retaining element is at least partially arranged in the receiving chamber such that the retaining element radially overlaps the connecting shaft and the piston rod.

14. A pump according to any one of claims 12 and 13, wherein The connecting shaft extends completely axially through the retaining member.

15. A pump according to any preceding claim, wherein The air valve comprises: a valve cover disposed on a first axial side of the piston head, the valve cover being engaged with the piston head when the air valve is in the open state and being disengaged from the piston head when the air valve is in the closed state; a valve base disposed on a second axial side of the piston head opposite to the first axial side of the piston head, the second axial side of the piston head being oriented toward the extender; a valve connector extending through the passage and between the valve cover and the valve base; and A channel seal is supported by the valve base, the channel seal engaging the piston head to fluidly separate a first drive chamber at least partially defined by the first axial side of the piston head from a second drive chamber at least partially defined by the second axial side of the piston head.

16. The pump according to claim 15, wherein The channel seal extends annularly around the connecting piece.

17. A pump comprising: Pump body; a piston disposed in the pump body and configured to reciprocate along a pump axis, the piston comprising a piston head and a piston shaft; an air valve supported by the piston, the air valve being actuatable between an open state and a closed state, wherein the air valve directs drive air to move the piston in a first axial direction along the pump axis through a first stroke when the air valve is in the closed state, and directs the drive air to move the piston in a second axial direction along the pump axis through a second stroke when the air valve is 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 transition the piston from the first stroke to the second stroke; as well as a stroke limiter supported by the piston, the stroke limiter being configured to interface with the air valve to actuate the air valve from the open state to the closed state, the stroke limiter comprising a bracket flange configured to interface with the pump body at an actuation interface to limit axial movement of the stroke limiter along the pump axis in the second axial direction, and the stroke limiter comprising a limit spring at least partially disposed on an axial side of the bracket flange opposite the piston head.

18. The pump according to claim 17, wherein The stroke limiter includes a spring chamber in which the limit spring is at least partially disposed, the spring chamber extending from the bracket flange in the second axial direction.

19. A pump according to any one of claims 17 and 18, wherein The limit spring is not fully compressed when the piston is at the end of the first stroke, and the limit spring is not fully compressed when the piston is at the end of the second stroke.

20. A pumping method, the method comprising: directing drive air to the first drive chamber through the air valve to drive the piston in a first axial direction along the pump axis by the drive air; engaging a retainer 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 retainer engaging the portion of the pump body such that the piston moves relative to the retainer and compresses a restraining spring located within a spring chamber formed in the retainer, the spring chamber extending in the first axial direction from an interface between the retainer and the pump body; actuating the air valve from an open state to a closed state via the stroke limiter interfacing with the air valve; as well as With the air valve in the closed state, the drive air is guided to the second drive chamber through the air valve to drive the piston along the pump axis in a second axial direction opposite to the first axial direction.

21. The method according to claim 20, wherein: Actuating the air valve from the open state to the closed state via the stroke limiter interfacing with the air valve comprises: engaging the air valve with a bracket supported by the limit spring; and As the piston continues to displace in the first axial direction, movement of the air valve along the pump axis is blocked by the bracket, so that the air valve is actuated to the closed state.

22. The method according to any one of claims 20 and 21, wherein: Driving the piston in the first axial direction with the retainer engaging the portion of the pump body such that the piston moves relative to the retainer and compresses a restraining spring located within a spring chamber formed within the piston includes: The piston is displaced in the first axial direction to displace the retainer axially outward from a receiving chamber formed in a piston shaft of the piston.

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