阅读说明：本技术 用于流体泵的可移除活塞杆套筒 (Removable piston rod sleeve for fluid pump ) 是由 杰里米·D·豪仑英 史蒂夫·J·弗罗贝尔 于 2018-02-22 设计创作，主要内容包括：承磨套筒可移除地安装在活塞杆上。活塞杆包括活塞帽、活塞杆本体和活塞头,其中活塞帽和活塞头中的至少一个可从活塞杆本体移除。承磨套筒设置在活塞杆本体上并防止活塞杆接触设置在泵内的动态密封件。承磨套筒被机械地固定在所述活塞杆上、在活塞帽的帽肩部和活塞头的头肩部之间的圆柱形凹部中。(A wear sleeve is removably mounted on the piston rod. The piston rod includes a piston cap, a piston rod body, and a piston head, wherein at least one of the piston cap and the piston head is removable from the piston rod body. A wear sleeve is disposed on the piston rod body and prevents the piston rod from contacting a dynamic seal disposed within the pump. A wear sleeve is mechanically secured to the piston rod in a cylindrical recess between a cap shoulder of the piston cap and a head shoulder of the piston head.)

1. A piston for pumping coating material through a displacement pump of a coating material spray system, the piston comprising:

a piston rod having a piston rod body elongated along an axis between a first end and a second end;

a piston head connected to the second end;

a cylindrical cutout extending around the piston rod body; and

a wear sleeve disposed around the piston rod body within the cylindrical relieved portion;

wherein the piston rod body is removably connected to the piston head by a mounting portion of the piston rod extending into a receiving portion of the piston head.

2. The piston of claim 1, wherein the receiving portion is a socket formed in the piston head and the mounting portion is a shank protruding from the second end.

3. The piston of claim 2, wherein the shank extends axially from the second end.

4. The piston of claim 2, wherein engaged threads are formed on the seat and the shank, the engaged threads securing the piston head to the piston rod body.

5. The piston of claim 1, wherein a check valve is disposed in the piston head.

6. The piston of any preceding claim, wherein a dynamic seal is provided on an outer surface of the piston head.

7. The piston of claim 6, wherein the dynamic seal is formed by a plurality of packing rings.

8. The piston of claim 1, further comprising:

a piston cap disposed at the first end, the piston cap including a radially protruding connecting portion.

9. The piston of any of claims 1-5 and 8, wherein the piston head comprises a piston head first end and a piston head second end, the receiving portion extending into the piston head first end and a central bore extending into the piston head second end, wherein at least one port extends through an outer surface of the piston head and is in fluid communication with the central bore.

10. The piston of claim 9, wherein the piston head includes a flange extending radially from an outer surface of the piston head.

11. The piston of claim 10, wherein a cutback is formed on the piston head between the piston head second end and the flange, the cutback configured to receive a dynamic seal.

12. The piston of claim 10, wherein at least a portion of the at least one port extends through the flange.

13. The piston of claim 9, wherein the piston head includes a head shoulder formed at the piston head first end, the head shoulder at least partially defining the cylindrical taper.

14. A displacement pump for a paint spray system, the displacement pump comprising:

a cylinder having an upstream end and a downstream end;

a first dynamic seal mounted in the cylinder; and

the piston of claim 1, wherein the piston extends through the first dynamic seal into the cylinder;

wherein the piston is configured to reciprocate within the cylinder and relative to the first dynamic seal; and is

Wherein the wear sleeve is disposed between the first dynamic seal and the piston such that the wear sleeve is the only portion of the piston that contacts the first dynamic seal during reciprocation.

15. The displacement pump of claim 14, further comprising:

a second dynamic seal disposed on an outer surface of the piston head, wherein the second dynamic seal is configured to reciprocate relative to the cylinder.

16. A piston for pumping coating material through a displacement pump of a coating material spray system, the piston comprising:

a piston rod body elongated along an axis between a first end and a second end;

a piston head connected to the second end; and

a first dynamic seal mounted on an outer surface of the piston head;

wherein the piston rod body is removably connected to the piston head by a mounting portion of the piston rod extending into a receiving portion of the piston head.

17. The piston of claim 16, wherein the receiving portion is a socket formed in the piston head and the mounting portion is a shank protruding from the second end.

18. The piston of claim 17, wherein the shank includes external threads and the socket includes internal threads configured to mate with the external threads to secure the piston head to the piston rod body.

19. The piston of any of claims 16 to 18, wherein the piston head comprises a piston head first end and a piston head second end, the receiving portion extending into the piston head first end and a central bore extending into the piston head second end, wherein at least one port extends through an outer surface of the piston head and is in fluid communication with the central bore.

20. The piston of claim 19, wherein the piston head includes a flange extending radially from an outer surface of the piston head, and wherein the at least one port is disposed on a first side of the flange and the first dynamic seal is disposed on a second side of the flange.

Technical Field

The present disclosure relates generally to piston rods. More particularly, the present disclosure relates to removable wear sleeves for piston rods.

Background

Fluid dispensing systems, such as those used for paints and other solutions, typically utilize an axial displacement pump to draw fluid from a fluid source and drive the fluid downstream. An axial displacement pump includes a piston driven in a reciprocating motion along its longitudinal axis to pump fluid. As the piston reciprocates, fluid is drawn into the pump and driven downstream. Displacement pumps include dynamic seals to prevent fluid from leaking around the piston. Due to a combination of factors, such as the high pressures generated during pumping; periodic relative movement of the engaging components such as the piston and dynamic seal; and the abrasive nature of the pumped fluid, significant wear of the piston may occur. Even where the piston is made of high grade hardened steel, the abrasive nature and high pressure of the pumped fluid can cause excessive wear to the piston. If the piston wears, the entire piston needs to be replaced.

Disclosure of Invention

According to one aspect of the present disclosure, a piston rod for a pump includes a piston rod body elongated between a first end and a second end, a piston cap connected to the first end, and a piston head connected to the second end. The piston cap includes a cap shoulder extending radially relative to the first end. The piston head includes a shoulder portion extending radially relative to the second end. A cylindrical relief (relief) extends around the piston rod body between the cap shoulder and the head shoulder, and the cylindrical relief is capable of receiving a wear sleeve. The piston rod body is removably connected to at least one of the piston cap and the piston head.

According to another aspect of the present disclosure, a pump includes a cylinder having an upstream end and a downstream end, a dynamic seal mounted in the cylinder, and a piston extending into the cylinder and through the first dynamic seal. The piston is configured to reciprocate within the cylinder and relative to the dynamic seal. The piston includes: a piston rod body elongated between a first end and a second end; a piston cap connected to the first end and including a head shoulder; a piston head connected to the second end and including a head shoulder; a cylindrical cutout extending around the piston rod body between the cap shoulder and the head shoulder; and a wear sleeve mounted on the piston rod body within the cylindrical cutback. The cap shoulder extends radially relative to the first end. The head shoulder extends radially relative to the second end. The cylindrical cutback extends between the cap shoulder and the head shoulder. The piston rod body is removably connected to at least one of the piston cap and the piston head. The outer surface of the wear sleeve is the only portion of the piston that contacts the dynamic seal during the reciprocating pumping stroke of the piston within the cylinder.

According to yet another aspect of the present disclosure, a method of replacing a wear sleeve comprises: separating a first portion of a piston rod from a second portion of the piston rod; sliding a first wear sleeve off the piston rod body of the piston rod; sliding a second wear sleeve onto the piston rod body; and sandwiching the second wear sleeve between the upstream shoulder of the piston rod and the downstream shoulder of the piston rod by bonding the first portion of the piston rod to the second portion of the piston rod.

According to yet another aspect of the present disclosure, a removable sleeve for a piston rod having a piston cap, a piston head, and a piston rod body extending between and removably connected to at least one of the piston cap and the piston head, the removable sleeve comprising: a first end configured to abut a cap shoulder of the piston cap; a second end configured to abut a shoulder portion of the piston head; and a cylindrical sleeve body extending between the first end and the second end. The cylindrical sleeve body receives the piston rod body. The cylindrical sleeve body is formed of ceramic.

Drawings

Fig. 1A is an isometric view of a fluid dispensing system.

Fig. 1B is an exploded view of the fluid dispensing system.

Fig. 2A is an isometric view of a displacement pump.

Fig. 2B is a cross-sectional view of the displacement pump of fig. 2A taken along line B-B shown in fig. 2A.

Fig. 3A is an exploded view of the piston.

Fig. 3B is a cross-sectional view of the piston.

Fig. 4A is an exploded view of the piston.

Fig. 4B is a cross-sectional view of the piston.

Fig. 5A is a cross-sectional view of a displacement pump.

Fig. 5B is an exploded view of the piston.

Fig. 5C is a cross-sectional view of the piston.

Fig. 6A is an exploded view of the piston.

Fig. 6B is a cross-sectional view of the piston.

Detailed Description

Pumps according to the present disclosure reciprocate a piston within a cylinder to pump various fluids, examples of which include paint, water, oil, stains, finishes, aggregates, coatings, solvents, and the like. Displacement pumps may produce high fluid pumping pressures, such as 3,000 to 5,000 pounds per square inch or even higher. High fluid pumping pressures are used to atomize fluids into a spray for application to a surface. The generation of high fluid pumping pressures can result in accelerated wear of the components of the pump that reciprocate relative to each other. As discussed further herein, aspects of the present disclosure may reduce or minimize the effects of wear in displacement pumps.

Fig. 1A is an isometric view of a fluid dispensing system 10. Fig. 1B is an exploded view of fluid dispensing system 10. Fig. 1A and 1B will be discussed together. Fluid dispensing system 10 includes a frame 12, a motor portion 14, a drive housing 16, a displacement pump 18, a reciprocating drive 20 (fig. 1B), a control system 22, an inlet hose 24, a supply hose 26, a dispensing hose 28, a housing cover 30, and a handle 32. As shown in fig. 1B, the motor section 14 includes a motor housing 34 and a drive gear 36, and the drive gear 36 includes an eccentric drive pin 37. The drive housing 16 includes an upper portion 38 and a lower portion 40. The upper portion 38 includes a gear aperture 42 and a link aperture 44. The lower portion 40 includes a mounting cavity 46 and a guard 48. As shown in fig. 1B, displacement pump 18 includes a piston 50 (which includes a piston rod 52 and a wear sleeve 54 (shown in fig. 2B-6B)), a cylinder 56, an inlet housing 58, and a clamp 60. The cylinder 56 includes an upstream end 62, a downstream end 64, and an outlet port 66. The inlet housing 58 includes an inlet port 68. The reciprocating drive 20 includes a connecting rod 70 and a drive link 72. The control system 22 includes a control housing 74. The inlet hose 24 includes an inlet fitting 76 and the supply hose 26 includes a supply fitting 78.

The frame 12 supports the motor section 14, and the drive housing 16 is mounted to the motor section 14. Fasteners 80a (fig. 1B) extend through the drive housing 16 and into the motor section 14 to secure the drive housing 16 to the motor section 14. The handle 32 is attached to the drive housing 16 by a fastener 80B (fig. 1B), which fastener 80B extends through the drive housing 16 and into the handle 32. Housing cover 30 is attached to upper portion 38 of drive housing 16 and encloses upper portion 38 of drive housing 16. The drive gear 36 is disposed within the motor section 14 and extends into the upper portion 38 of the drive housing 16 through a gear aperture 42. The drive gear 36 is driven by a motor (not shown) disposed within the motor housing 34. The eccentric drive pin 37 extends into the upper portion 38 and is configured to engage the connecting rod 70. Any desired motor may be used to power the drive gear 36. For example, the fluid distribution system 10 may be powered electrically, pneumatically, or hydraulically.

The upper portion 38 of the drive housing 16 is integral with the lower portion 40 of the drive housing 16. A gear aperture 42 extends through a rear side of the upper portion 38 and a link aperture 44 extends through the drive housing 16 between the upper portion 38 and the lower portion 40. Mounting cavity 46 extends into lower portion 40 and is configured to receive displacement pump 18. A guard 48 is mounted on the lower portion 40 and is configured to cover the mounting cavity 46.

A reciprocating drive 20 is disposed within the drive housing 16. The drive link 72 is attached to the connecting rod 70. The connecting rod 70 is disposed within the upper portion 38 of the drive housing, and the drive link 72 extends through the link aperture 44 and into the mounting cavity 46. The connecting rod 70 is attached to the drive gear 36 and driven by the drive gear 36, with the drive gear 36 extending into the upper portion 38 through the gear aperture 42. The connecting rod 70 and the eccentric drive pin 37 convert the rotational motion of the drive gear 36 into linear motion of the drive link 72.

Displacement pump 18 is at least partially disposed within mounting cavity 46 and may be secured by clamp 60. Clamp 60 extends around cylinder 56 and clamp 60 secures displacement pump 18 to lower portion 40 of drive housing 16. Although displacement pump 18 is described as being secured to drive housing 16 by clamp 60 disposed on cylinder 56, it should be appreciated that displacement pump 18 may be mounted in any suitable manner. For example, displacement pump 18 may include external threads configured to mate with threads on drive housing 16, or displacement pump 18 may be secured by a clamping mechanism integral with drive housing 16.

Inlet housing 58 is attached to an upstream end 62 of cylinder 56 to form the body of displacement pump 18. Piston 50 is at least partially disposed within displacement pump 18. The piston rod 52 extends into the cylinder 56 through a downstream end 64 of the cylinder 56. One end of the piston rod 52 extending from the cylinder 56 is connected to a drive link 72, and the drive link 72 is configured to drive the piston rod 52 in a reciprocating manner. Piston rod 52 may be connected to drive link 72 in any suitable manner; for example, piston rod 52 may include a head that fits within a slot of drive link 72, or piston rod 52 may be pinned to drive link 72.

An inlet hose 24 extends between the fluid source and the displacement pump 18. An inlet fitting 76 is connected to the inlet port 68 to provide fluid to the inlet housing 58. Supply hose 26 extends between outlet port 66 of cylinder 56 and control housing 74 to provide fluid from displacement pump 18 to control housing 74. Supply fitting 78 connects to outlet port 66 to attach supply hose 26 to displacement pump 18. The dispensing hose 28 is connected to the control housing 74 and extends between the control housing 74 and a dispenser (not shown), such as a spray gun. The control system 22 includes various components, such as pressure regulators and trigger valves, for setting the flow rate and flow pressure of the fluid, as well as other operating criteria. The dispensing hose 28 provides fluid downstream of the dispensing system 10.

During operation, the motor of the motor part 14 drives the drive gear 36 in a rotating manner, and due to the connection of the eccentric drive pin 37 and the connecting rod 70, the connecting rod 70 will follow the drive gear 36. The connecting rod 70 converts the rotational motion of the drive gear into linear motion of the drive link 72 such that the drive link 72 reciprocates through the link aperture 44. Thus, due to the connection of the piston rod 52 and the drive link 72, the drive link 72 drives the piston 50 in a reciprocating motion. Driving piston 50 in a reciprocating manner causes piston 50 to draw fluid into displacement pump 18 through inlet hose 24 and inlet housing 58, and pump the fluid downstream through cylinder 56 and supply hose 26.

Fluid is drawn from an external source (e.g., a tank) through inlet hose 24 and into displacement pump 18 through inlet port 68. Fluid is driven by piston 50 through displacement pump 18 and fluid exits displacement pump 18 through outlet port 66 in cylinder 56. Fluid flows from the outlet port 66 into the supply hose 26 and to the control housing 74. The fluid exits the control housing 74 through the dispensing hose 28 and flows downstream to a dispenser where it can be dispensed for any desired purpose, such as applying paint to a surface with a spray gun. Displacement pump 18 thus draws fluid from a container through inlet hose 24, drives the fluid downstream through supply hose 26 to control system 22, and drives the fluid through dispensing hose 28 and to a dispenser where the fluid is applied in any desired manner.

Fig. 2A is an isometric view of displacement pump 18. Fig. 2B is a cross-sectional view of displacement pump 18 taken along line B-B in fig. 2A. Displacement pump 18 includes piston 50, cylinder 56, inlet housing 58, first check valve 82, second check valve 84, first dynamic seal 86a, and second dynamic seal 86 b. The piston 50 includes a piston rod 52 and a wear sleeve 54. The piston rod 52 includes a piston cap 88, a piston rod body 90, and a piston head 92. Wear sleeve 54 includes a sleeve body 94, a first end 96 and a second end 98. The piston cap 88 includes a socket 100, a cap shoulder 102, and a connecting portion 104. The piston rod body 90 includes an upstream end 106, a downstream end 108, a seal groove 110, and a shank 112. The piston head 92 includes a central bore 114, a flange 116, a head shoulder 118, and a cutback 119. The cylinder 56 includes an outlet port 66 (shown in fig. 2A), a first fluid chamber 120, a second fluid chamber 122, and an inner cylinder portion 124. The inlet housing 58 includes an inlet port 68. The first check valve 82 includes a cage 126, a first ball 128, and a first seat 130. The second check valve 84 includes a second ball 132, a second seat 134, and a retainer 136. Dynamic seal 86a includes an packing ring 138a and a gland 140a, and dynamic seal 86b includes a packing ring 138b and a gland 140 b. The generally downstream direction is indicated by a downstream arrow and the generally upstream direction is indicated by an upstream arrow.

An inlet housing 58 is mounted to the cylinder 56. The outlet port 66 extends through the cylinder 56. The piston 50 is at least partially disposed within the cylinder 56. Piston 50 extends along a longitudinal axis L-L, wherein longitudinal axis L-L is oriented coaxially with the generally elongated profile of displacement pump 18. The piston rod 52 extends into the cylinder 56 through a cap 63 and a packing nut 65. The piston rod 52 is elongated along the longitudinal axis L-L. The piston rod 52 may be formed of any suitable durable material to withstand the high pressures associated with pumping. For example, the piston rod 52 may be machined or cast from steel, brass, aluminum, or any other suitable metal. In some examples, the piston rod 52 may be formed of hardened 440C stainless steel. The components of the piston rod 52, such as the piston cap 88, the piston rod body 90, and the piston head 92, may be manufactured separately.

A first check valve 82 is mounted in the inlet housing 58. A ball retainer 126 is disposed within the inlet housing 58 and a first ball 128 is disposed within the ball retainer 126. In some examples, the ball retainer 126 is molded from a polymer, but it should be understood that the ball retainer 126 may be formed from any suitable durable material for retaining the first ball 128 through repeated oscillation cycles. The first seat 130 is disposed between the ball retainer 126 and the inlet port 68 of the inlet housing 58. The second check valve 84 is disposed within the central bore 114 of the piston head 92. The retainer 136 engages the inner surface of the piston head 92, such as by threads, to secure the second seat 134 within the piston head 92. In some examples, the second seat 134 is integrally formed on a downstream end of the retainer 136. A second ball 132 is disposed within the piston head 92. The second seat 134 and the retainer 136 are fixed relative to the piston head 92. First ball 128 and second ball 132 may be formed of stainless steel or any other suitable material to form a seal with first seat 130 and second seat 134, respectively. The first and second sockets 130, 134 may be formed of a high strength material such as tungsten carbide.

A dynamic seal 86a is disposed between the cylinder 56 and the piston rod 52. The cap 63 and packing nut 65 attach to the downstream end 108 of the cylinder 56 and retain the dynamic seal 86a within the cylinder 56. The packing ring 138a is retained on the cylinder 56 such that the dynamic seal 86a remains stationary relative to the cylinder 56 as the piston 50 reciprocates relative to the cylinder 56 during operation. Wear sleeve 54 is positioned along a portion of piston rod 52 that overlaps with packing ring 138a along longitudinal axis L-L throughout the range of reciprocation of piston 50. An excluder ring 138a surrounds the wear sleeve 54 and tightly engages the wear sleeve 54 to form a seal around the piston 50 to prevent leakage of the pumped fluid from the downstream end 108 of the cylinder 56. The packing ring 138a is held between the gland 140 a. The gland 140a may be a metal retaining ring or the like. The encapsulation ring 138a may be formed of leather, polymer, and/or any other suitable sealing material.

Dynamic seal 86b is located on the cutback 119 of piston head 92 and around the cutback 119 and provides a fluid seal between piston head 92 and cylinder 56. An packing ring 138b is mounted on the piston head 92 and is retained by a gland 140 b. A flange 116 extends radially from piston head 92 and is disposed at a downstream end of dynamic seal 86. The flange 116 prevents the downstream gland 140b, and therefore the packing ring 138b, from moving in a downstream direction relative to the piston rod 52. The retainer 136 supports the upstream gland 140b to prevent the gland 140b and thus the packing ring 138b from moving in the upstream direction relative to the piston rod 52. The dynamic seal 86b divides the cylinder 56 into a first fluid chamber 120 and a second fluid chamber 122. In the example shown, the dynamic seal 86b reciprocates with the piston rod 52 relative to the cylinder 56. However, it should be understood that the dynamic seal 86b may be mounted on the cylinder 56 such that the dynamic seal 86b remains stationary relative to the cylinder 56 as the piston rod 52 reciprocates relative to the dynamic seal 86 b. The gland 140b may be a metal retaining ring or the like. The encapsulation ring 138b may be formed of leather, polymer, and/or any other suitable sealing material. Although displacement pump 18 is shown as including two dynamic seals 86, it should be understood that displacement pump 18 may include any number of dynamic seals 86. Further, while the dynamic seal 86 is shown as including a stack of packing rings 138, it should be understood that the dynamic seal 86 may have any desired configuration, such as a single polymeric ring that fits around the piston rod 52 within the cylinder 56 and includes inner and/or outer projecting ribs that engage and seal with the outer surface of the piston rod 52 and/or the inner cylinder portion 124 of the cylinder 56.

A piston rod body 90 extends between the piston cap 88 and the piston head 92. The socket 100 extends into the piston cap 88. A stem 112 extends from the downstream end 108 of the piston rod body 90 and into the socket 100. A stem 112 is received in the socket 100 to removably connect the piston rod body 90 and the piston cap 88. In some examples, the hub 100 includes internal threads and the shank 112 includes external threads configured to mate with the internal threads to connect the piston rod body 90 and the piston cap 88. It should be understood that the piston rod body 90 and the piston cap 88 may be connected in any desired manner that allows the piston cap 88 to be removed from the piston rod body 90. For example, a hole may extend through the piston cap 88 and the stem 112, and a pin may be received in the hole to secure the stem 112 within the socket 100. The piston head 92 is integral with the piston rod body 90 such that the piston head 92 and the piston rod body 90 are formed from a single piece. However, it should be understood that both the piston head 92 and the piston cap 88 may be removably connected to the piston rod body 90 such that the piston rod 52 is formed of three separable pieces. The connecting portion 104 of the piston cap 88 is configured to be connected to a drive mechanism, such as the reciprocating drive 20, to facilitate reciprocating movement of the piston 50. The cap shoulder 102 is the portion of the piston cap 88 that extends radially relative to the piston rod body 90. The head shoulder portion 118 is the portion of the piston head 92 that extends radially relative to the piston rod body 90. The cap shoulder 102 and the head shoulder 118 define a cylindrical cutout 142 extending around the piston rod body 90. Although the terms head shoulder 118 and cap shoulder 102 are used herein, it should be understood that the cap shoulder 102 and head shoulder 118 need not be integral with the piston cap 88 and piston head 92, respectively. The cap shoulder 102 and the head shoulder 118 may refer to any two shoulders closer to the piston cap 88 and the piston head 92, respectively, for retaining the wear sleeve 54. Any reference to the cap shoulder 102 may be replaced with the term first shoulder and/or downstream shoulder, and any reference to the head shoulder 118 may be replaced with the term second shoulder and/or upstream shoulder.

The wear sleeve 54 is tubular and is disposed on the piston rod body 90. Wear sleeve 54 is coaxially aligned with piston rod 52, and specifically with piston rod body 90. Wear sleeve 54 is disposed in cylindrical cutback 142 and is secured to piston rod body 90 by head shoulder 118 and cap shoulder 102. The first end 96 of the wear sleeve 54 abuts the head shoulder 118 and the second end 98 of the wear sleeve 54 abuts the cap shoulder 102. In the example shown, the inner surface of the wear sleeve 54 contacts the radially outer surface of the piston rod body 90 along the entire length of the sleeve body 94. However, it should be understood that the central portion of the piston rod body 90 may have a reduced diameter such that a chamber is formed between the sleeve body 94 and the piston rod body 90. In such an example, the downstream end 108 and the upstream end 106 of the piston rod body 90 are sized to remain in contact with the sleeve body 94 while the chamber extends between the upstream end 106 and the downstream end 108, thereby ensuring concentricity of the wear sleeve 54 and the piston rod body 90. With the wear sleeve 54 mounted on the piston rod 52, the piston 50 has a uniform outer diameter along the longitudinal axis L-L between the piston cap 88, the wear sleeve 54, and the piston head 92.

Wear sleeve 54 may be formed of a different material than piston rod 52. For example, the wear sleeve 54 may be formed of metal, ceramic, or the like. The wear sleeve 54 may also be hardened prior to use. In some examples, wear sleeve 54 is formed from yttria stabilized zirconia, alumina, tungsten carbide, silicon nitride, and the like. The wear sleeve 54 may therefore be formed of a harder material than the metal of the piston rod 52, such that the wear sleeve 54 is better able to withstand the frictional forces experienced during pumping. Where wear sleeve 54 is the only component of piston 50 that contacts dynamic seal 86a, piston rod 52 may be formed of a softer metal and/or may be subjected to less hardening than is typically required to withstand the grinding caused during pumping.

The wear sleeve 54 is removable from the piston rod 52. The piston cap 88 is removed from the piston rod body 90 by rotating the piston cap 88 to unscrew the stem 112 from the socket 100. With the piston cap 88 removed, the wear sleeve 54 may be pulled out of the piston rod body 90. Wear sleeve 54 is mounted on piston rod 52 by sliding wear sleeve 54 onto piston rod body 90 and threading piston cap 88 onto piston rod body 90. Accordingly, the wear sleeve 54 may be quickly and efficiently replaced to provide a new wear surface for the piston 50.

The sealing groove 110 extends to the upstream end 106 of the piston rod body 90 near the piston head 92. The seal groove 110 receives a seal 144 disposed between the piston rod body 90 and the wear sleeve 54. The seal 144 prevents the pumped fluid from moving into the space between the piston rod body 90 and the sleeve body 94. In some examples, the seal 144 is an O-ring, such as an elastomeric O-ring. However, it should be understood that the seal 144 may be any suitable configuration for preventing pumped fluid from moving between the piston rod body 90 and the sleeve body 94. For example, the seal 144 may be a washer disposed on the head shoulder 118 and captured between the head shoulder 118 and the first end 96 of the wear sleeve 54. Further, although the seal 144 is described as being disposed within the seal groove 110, it should be appreciated that the seal 144 may be retained in any desired manner. For example, the seal 144 may be disposed on the head shoulder 118, and the first end 96 of the wear sleeve 54 may include a chamfer to fit the seal 144 and maintain a seal on the head shoulder 118. In other examples, the wear sleeve 54 may include a groove extending into the sleeve body 94 to receive the seal 144.

During operation, piston 50 is driven through an upstroke and a downstroke along longitudinal axis L-L by a drive mechanism, such as reciprocating drive 20, to draw fluid into displacement pump 18 and drive fluid downstream from displacement pump 18. During the upstroke, the piston 50 is drawn in a downstream direction (represented by the downstream arrow in FIG. 2B) along the longitudinal axis L-L. When the piston 50 moves in the downstream direction, the volume of the first fluid chamber 120 increases and the volume of the second fluid chamber 122 decreases as the piston head 92 and dynamic seal 86b displace in the downstream direction. The expanded first fluid chamber 120 experiences a vacuum condition that causes the first ball 128 to displace to an open position in which the first ball 128 is disengaged from the first seat 130. The flow path is thus opened through the first check valve 82 and fluid is drawn into the first fluid chamber 120 through the inlet port 68 and the first check valve 82. During the upstroke, the second ball 132 is pushed against the second seat 134 and forms a seal with the second seat 134 to prevent the fluid within the second fluid chamber 122 from flowing upstream into the first fluid chamber 120. As the volume of the second fluid chamber 122 decreases, fluid within the second fluid chamber 122 is driven downstream through the outlet port 66 in the cylinder 56.

After the completion of the upstroke, the piston 50 travels in reverse and is driven through the downstroke. During the downstroke, the piston 50 is driven in the upstream direction (indicated by the upstream arrow in fig. 2B). During the downstroke, the volume of the first fluid chamber 120 decreases and the volume of the second fluid chamber 122 increases. When the piston 50 switches from the upstroke to the downstroke, the second ball 132 disengages from the second seat 134, providing a flow path through the piston head 92 between the first and second fluid chambers 120, 122. The first ball 128 engages the first seat 130, closing the first check valve 82 and preventing backflow of fluid from the first fluid chamber 120 through the inlet port 68. As the piston 50 moves through the downstroke, fluid within the first fluid chamber 120 flows downstream through the retainer 136, the piston head 92, the second check valve 84, and the piston port 146 (shown in fig. 3A-4B and 5B-6B) to the second fluid chamber 122. The outlet port 66 is in open fluid communication with the second fluid chamber 122 and, as should be appreciated, fluid is driven downstream through the outlet port 66 during the upstroke and downstroke of the piston 50.

The dynamic seal 86 prevents fluid and air from flowing between the inner surface of the cylinder 56 and the outer surface of the piston 50 during the upstroke and downstroke. The two dynamic seals 86 are tightly contained to establish vacuum conditions in the first and second fluid chambers 120, 122 and to apply positive pressure during the reciprocation cycle of the piston 50. The wear sleeve 54 is the only portion of the piston 50 that contacts the dynamic seal 86a during reciprocation of the piston 50. Accordingly, the wear sleeve 54 prevents any portion of the dynamic seal 86a from contacting any portion of the piston rod 52 (including the piston cap 88, the piston rod body 90, and the piston head 92). Thus, wear sleeve 54 protects piston rod 52 from wear caused by relative movement at the interface of piston rod 52 and dynamic seal 86 a.

The wear sleeve 54 provides significant advantages. Wear sleeve 54 experiences all of the frictional forces caused by the reciprocating motion of piston 50 relative to dynamic seal 86 a. Because the wear sleeve 54 is the only portion of the piston 50 that is subject to wear generated by the dynamic seal 86a during reciprocation, the piston rod 52 may be formed from a softer metal and/or may experience less hardening, thereby reducing manufacturing costs. Further, the wear sleeve 54 can be easily removed and replaced on the piston rod 52 by unscrewing the piston cap 88 from the piston rod body 90, pulling the wear sleeve 54 out of the piston rod body 90, and replacing a new wear sleeve 54 on the piston rod body 90. The wear sleeve 54 is removable, which saves cost and reduces the downtime previously required to replace the worn piston 50. In a particularly abrasive environment, the wear sleeve 54 may be made of a suitably strong and inexpensive material to facilitate multiple replacements throughout the pumping process while utilizing a single piston 50.

Fig. 3A is an exploded view of the piston 50. Fig. 3B is a cross-sectional view of the piston 50. Fig. 3A and 3B will be discussed together. The piston 50 includes a piston rod 52 and a wear sleeve 54. The piston rod 52 includes a piston cap 88, a piston rod body 90, and a piston head 92. Wear sleeve 54 includes a sleeve body 94, a first end 96 and a second end 98. The piston cap 88 includes a socket 100, a cap shoulder 102, and a connecting portion 104. The piston rod body 90 includes an upstream end 106, a downstream end 108, a seal groove 110, and a shank 112. The piston head 92 includes a central bore 114, a flange 116, a head shoulder 118, and a piston port 146.

The piston rod body 90 is integral with the piston head 92 and extends longitudinally from the piston head 92. The central bore 114 extends into the piston head 92 and is configured to receive a check valve, such as the second check valve 84 (shown in fig. 2B and 4). The piston port 146 extends through the piston head 92 and provides a flow path for fluid flowing downstream out of the piston head 92. A flange 116 extends radially from the piston head 92 and is configured to support a seal, such as dynamic seal 86B (shown in fig. 2B and 4), that is mounted around a cutback 119. A head shoulder 118 extends radially from the piston head 92 relative to the piston rod body 90 and is disposed near the upstream end 106 of the piston rod body 90. The sealing groove 110 extends into the upstream end 106 of the piston rod body 90. The seal groove 110 receives a seal 144.

A shank 112 extends from the downstream end 108 of the piston rod body 90 and is configured to engage the socket 100. The stem 112 is secured within the socket 100 to attach the piston rod body 90 to the piston cap 88. A connecting portion 104 extends from the piston cap 88 and is configured to engage a drive mechanism, such as the reciprocating drive 20 (shown in fig. 1B), to facilitate reciprocating movement of the piston 50. A cap shoulder 102 extends radially from the piston cap 88 relative to the piston rod body 90. In some examples, the shank 112 includes external threads configured to mate with internal threads in the socket 100. In other examples, a hole extends through the stem 112 and the socket 100, and the hole is configured to receive a pin to secure the stem 112 within the socket 100, thereby connecting the piston cap 88 and the piston rod body 90.

The cap shoulder 102 and the head shoulder 118 define a cylindrical cutout 142 that extends axially along the length of the piston rod body 90 between the piston cap 88 and the piston head 92. The wear sleeve 54 is disposed on the piston rod body 90 in the cylindrical cutout 142 and extends between the piston cap 88 and the piston head 92. The sleeve body 94 is cylindrical and receives the piston rod body 90. With the wear sleeve 54 disposed on the piston rod body 90, the first end 96 of the wear sleeve 54 abuts the head shoulder 118 and the second end 98 of the wear sleeve 54 abuts the cap shoulder 102.

Wear sleeve 54 is secured to piston rod body 90 by head shoulder 118 and cap shoulder 102. Wear sleeve 54 covers piston rod body 90 such that piston rod body 90 is prevented from contacting abrasive wear surfaces such as dynamic seal 86a (shown in fig. 2B and 4) during operation. Wear sleeve 54 is a replaceable wear component of piston 50 that extends the useful life of piston rod 52 by preventing direct contact between piston rod 52 and dynamic seal 86 a. With the wear sleeve 54 mounted on the piston rod 52, the piston 50 has a uniform outer diameter between the piston cap 88, the wear sleeve 54, and the piston head 92. As described above, the wear sleeve 54 may be made of any desired material, such as metal or ceramic.

The wear sleeve 54 is mechanically fixed to the piston rod 52. No adhesive is used to secure wear sleeve 54 to piston rod 52. Mechanically securing the wear sleeve 54 to the piston rod 52 facilitates removal and replacement of the wear sleeve 54. The clamping force exerted on the wear sleeve 54 by the head shoulder 118 and the cap shoulder 102 secures the wear sleeve 54 to the piston rod 52. To remove the wear sleeve 54, the piston cap 88 is rotated relative to the piston rod body 90 to unscrew the shank 112 from the socket 100 and pull the piston cap 88 out of the piston rod body 90. With the piston cap 88 removed, the wear sleeve 54 may be pulled out of the piston rod body 90. To install the wear sleeve 54 on the piston rod 52, the wear sleeve 54 is slid onto the piston rod body 90 such that the shank 112 extends from the second end 98 of the wear sleeve 54. The piston cap 88 is attached to the piston rod body 90 by threading the shank 112 into the socket 100. With the piston cap 88 reattached to the piston rod body 90, the wear sleeve 54 is secured between the head shoulder 118 and the cap shoulder 102.

The wear sleeve 54 provides significant advantages. Wear sleeve 54 protects piston rod 52 from wear due to movement relative to dynamic seal 86 a. Since the wear sleeve 54 is subject to all wear caused by the dynamic seal 86a, the piston rod 52 may be made of a softer metal and/or may be subject to less hardening, thereby saving manufacturing costs. Additionally, the wear sleeve 54 is replaceable, thereby extending the useful life of the piston rod 52 by allowing the user to replace the wear sleeve 54 and continue to use the same piston rod 52, which saves replacement costs. Wear sleeve 54 is retained on piston rod body 90 by head shoulder 118 and cap shoulder 102 without the use of adhesives, which facilitates quick and efficient removal and replacement of wear sleeve 54.

Fig. 4A is an exploded view of the piston 50'. Fig. 4B is a cross-sectional view of the piston 50'. The piston 50 'includes a piston rod 52' and a wear sleeve 54. The piston rod 52 'includes a piston cap 88', a piston rod body 90', and a piston head 92'. Wear sleeve 54 includes a sleeve body 94, a first end 96 and a second end 98. The piston cap 88' includes a cap shoulder 102' and a connecting portion 104 '. The piston rod body 90' includes an upstream end 106', a downstream end 108', a seal groove 110', and a shank 112 '. Piston head 92' includes a socket 100', a central bore 114', a flange 116', a head shoulder 118', a relieved portion 119', and a piston port 146 '.

The piston rod body 90' is integral with the piston cap 88' and extends longitudinally from the piston cap 88 '. A connecting portion 104' extends from the piston cap 88' and is configured to engage a drive member, such as the reciprocating drive 20 (shown in fig. 1B), to facilitate reciprocating movement of the piston 50 '. Cap shoulder 102' extends radially from piston cap 88' relative to piston rod body 90' and is disposed near a downstream end 108' of piston rod body 90 '. The shank 112' extends from the upstream end 106' of the piston rod body 90' and includes external threads. The seal groove 110' extends into the upstream end 106' of the piston rod body 90' proximate the shank 112', and the seal groove 110' receives the seal 144. The seal 144 may be any suitable seal for preventing fluid from migrating to the interface between the wear sleeve 54 and the piston rod body 90'. For example, the seal 144 may be an elastomeric O-ring.

Seat 100 'extends into the downstream end of piston head 92' and central bore 114 'extends into the upstream end of piston head 92'. The socket 100 'includes internal threads configured to mate with external threads on the shank 112' to attach the piston head 92 'and the piston rod body 90'. A piston port 146' extends through the piston head 92' and is in fluid communication with the central bore 114 '. The piston ports 146 'provide a flow path for fluid to flow downstream out of the piston head 92'. A flange 116 'extends radially from the piston head and is configured to support a seal, such as dynamic seal 86B (shown in fig. 2B and 5A), that is mounted around a cutback 119'. A head shoulder 118' is formed on a portion of the piston head 92' that extends radially relative to the piston rod body 90 '.

The cap shoulder 102 'and the head shoulder 118' define a cylindrical cutout 142 'that extends along the length of the piston rod body 90' between the piston cap 88 'and the piston head 92'. The wear sleeve 54 is disposed in the cylindrical cutback 142' and extends between the piston cap 88' and the piston head 92 '. The sleeve body 94 is cylindrical and surrounds the piston rod body 90'. The first end 96 of the wear sleeve 54 abuts the head shoulder 118', and the second end 98 of the wear sleeve 54 abuts the cap shoulder 102'. With the wear sleeve 54 mounted on the piston rod 52', the piston 50' has a uniform outer diameter between the piston cap 88', the wear sleeve 54, and the piston head 92'. Wear sleeve 54 covers piston rod body 90' such that piston rod body 90' is prevented from contacting abrasive wear surfaces, such as dynamic seal 86a, as piston 50' reciprocates during operation. The wear sleeve 54 is a replaceable wear component of the piston 50 'that extends the life of the piston rod 52'. As described above, the wear sleeve 54 may be made of any desired material, such as metal or ceramic.

The wear sleeve 54 is mechanically secured to the piston rod 52' by the clamping force exerted on the wear sleeve 54 by the head shoulder 118' and the cap shoulder 102 '. No adhesive is used to secure the wear sleeve 54 to the piston rod 52'. Mechanically securing the wear sleeve 54 facilitates removal and replacement of the wear sleeve 54. To remove the wear sleeve 54, the piston head 92 'is rotated relative to the piston rod body 90' to unscrew the shank 112 'from the socket 100'. The piston head 92 'is pulled out of the piston rod body 90'. With the piston head 92 'removed, the wear sleeve 54 is pulled out of the piston rod body 90'. To install the wear sleeve 54 on the piston rod 52', the wear sleeve 54 is slid onto the piston rod body 90' such that the shank 112' extends from the first end 96 of the wear sleeve 54. The piston head 92 'is attached to the piston rod body 90' by threading the shank 112 'into the socket 100'. With the piston head 92 'reattached to the piston rod body 90', the wear sleeve 54 is secured between the head shoulder 118 'and the cap shoulder 102'.

Fig. 5A is a cross-sectional view of displacement pump 18 including piston 50 ". Fig. 5B is an exploded view of the piston 50 ". Fig. 5C is a cross-sectional view of the piston 50 ". Fig. 5A to 5C will be discussed together. Displacement pump 18 is similar in function to displacement pump 18 shown in fig. 2A and 2B. Accordingly, like parts are indicated with like numerals and their operation and arrangement will not be discussed in detail.

The piston 50 "includes a piston rod 52" and a wear sleeve 54. The piston rod 52 "includes a piston cap 88", a piston rod body 90 ", and a piston head 92". Wear sleeve 54 includes a sleeve body 94, a first end 96 and a second end 98. The piston cap 88 "includes a cap shoulder 102", a connecting portion 104 ", and a shank 112". Piston rod body 90 "includes a socket 100", an upstream end 106 ", a downstream end 108" and a seal groove 110 ". Piston head 92 "includes a central bore 114", a flange 116 ", a head shoulder 118", a cutout 119 ", and a piston port 146".

Piston 50 "extends along longitudinal axis L-L and is configured to drive fluid through displacement pump 18. The piston rod 52 "extends into the cylinder through the cap 63 and packing nut 65 and is elongated along the longitudinal axis L-L. The piston rod 52 "may be formed of any suitable durable material to withstand the high pressures associated with pumping. For example, the piston 50 "may be machined or cast from steel, brass, aluminum, or any other suitable metal. In some examples, the piston 50 "may be formed of hardened 440C stainless steel.

A stem 112 "extends from the piston cap 88" and is received within the hub 100 ". In some examples, the socket 100 "includes internal threads and the shank 112" includes external threads configured to mate with the internal threads in the socket 100 "to secure the piston cap 88" to the piston rod body 90 ". In other examples, a hole may extend through the socket 100 "and the shank 112", and the hole may receive a pin to secure the piston cap 88 "to the piston rod body 90". In this manner, the piston cap 88 "is removably connected to the piston rod body 90". The connecting portion 104 "of the piston cap 88" is configured to connect the piston 50 "to a drive mechanism that drives the piston 50" in a reciprocating motion during operation. As shown, the connecting portion 104 "includes an aperture for receiving a pin that is driven in a reciprocating manner by a drive device, such as the reciprocating drive device 20 (shown in fig. 2B), to facilitate reciprocating movement of the piston 50". A cap shoulder 102 "extends radially from the piston cap 88" relative to the piston rod body 90 ".

The piston rod body 90 "is integral with the piston head 92" and is elongated along the longitudinal axis L-L. The socket 100 "extends into the downstream end 108" of the piston rod body 90 "and receives the shank 112". The socket 100 "may include internal threads configured to mate with external threads on the shank 112" such that the engaged threads secure the piston cap 88 "to the piston rod body 90". The sealing groove 110 "extends to the upstream end 106" of the piston rod body 90 "proximate the piston head 92". The seal 144 is at least partially disposed within the seal groove 110 ". Seal 144 provides a fluid tight seal between piston rod body 90 "and wear sleeve 54, and may be of any desired configuration for preventing pumped fluid from flowing into the interface between piston rod body 90" and sleeve body 94. In some examples, the seal 144 is an O-ring, such as an elastomeric O-ring. However, it should be understood that seal 144 may be any suitable configuration for preventing pumped fluid from moving between piston rod body 90 "and wear sleeve 54.

A head shoulder portion 118 "extends radially from the piston head 92" relative to the piston rod body 90 ". The central bore 114 "extends into the upstream end of the piston head 92" and receives the second check valve 84. The piston port 146 "extends through the piston head 92" downstream of the second check valve 84, and the piston port 146 "provides a flow path between the central bore 114" and the second fluid chamber 122 to allow pumped fluid to flow downstream out of the piston head 92 ". A flange 116 "extends radially from the piston head 92" and provides downstream support for the dynamic seal 86b to prevent the dynamic seal 86b from displacing downstream during reciprocation of the piston 50 ". Dynamic seal 86b is disposed around a relieved portion 119 "on piston head 92".

The head shoulder portion 118 "and the cap shoulder portion 102" define a cylindrical cutout 142 "that extends along the longitudinal length of the piston rod body 90". A wear sleeve 54 is disposed in the cylindrical cutout 142 "and surrounds the piston rod body 90". The sleeve body 94 is tubular and configured to receive the piston rod body 90 ". Wear sleeve 54 is positioned along a portion of piston rod 52 "that overlaps with packing ring 138a along longitudinal axis L-L throughout the range of reciprocation of piston rod 52". Wear sleeve 54 is coaxially aligned with piston rod 52 ", and in particular with piston rod body 90". The first end 96 of the wear sleeve 54 abuts the head shoulder 118 "and the second end 98 of the wear sleeve 54 abuts the cap shoulder 102". Although the terms head shoulder 118 "and cap shoulder 102" are used herein, it should be understood that the cap shoulder 102 "and head shoulder 118" need not be integral with the piston cap 88 "and piston head 92", respectively. The cap shoulder 102 "and the head shoulder 118" may refer to any two shoulders closer to the piston cap 88 "and the piston head 92", respectively, for retaining the wear sleeve 54. Any reference to the cap shoulder 102 "may be replaced with the term first shoulder and/or downstream shoulder, and any reference to the head shoulder 118" may be replaced with the term second shoulder and/or upstream shoulder.

Wear sleeve 54 is mechanically secured to piston rod body 90 "by head shoulder 118" and cap shoulder 102 ". No adhesive is used to secure the wear sleeve 54 to the piston rod 52 ". Mechanically securing the wear sleeve 54 to the piston rod body 90 "facilitates removal and replacement of the wear sleeve 54. To remove the wear sleeve 54 from the piston rod 52 ", the piston cap 88" is rotated relative to the piston rod body 90 "to unscrew the shank 112" from the socket 100 ". The piston cap 88 "is pulled away from the piston rod body 90". With the piston cap 88 "removed, the wear sleeve 54 is pulled out of the piston rod body 90". To install the wear sleeve 54 on the piston rod 52 ", the wear sleeve 54 is slid onto the piston rod body 90". The piston cap 88 "is attached to the piston rod body 90" by threading the shank 112 "into the socket 100". With the piston head 92 "reattached to the piston rod body 90", the wear sleeve 54 completely surrounds the piston rod body 90 "and is secured between the head shoulder 118" and the cap shoulder 102 ".

During operation, the piston 50 "reciprocates within the cylinder 56 and relative to the dynamic seal 86 a. Wear sleeve 54 is the only portion of piston 50 "that contacts dynamic seal 86a during reciprocation of piston 50". In this manner, wear sleeve 54 prevents any portion of dynamic seal 86a from contacting piston rod 52 "(including piston cap 88", piston rod body 90 ", and piston head 92"). Wear sleeve 54 experiences all of the frictional forces generated at the interface of dynamic seal 86a and piston 50 ". Thus, the wear sleeve 54 protects the piston rod 52 "from wear caused by movement relative to the dynamic seal 86 a.

As described above, wear sleeve 54 may be formed of a different material than piston rod 52 ". The piston rod 52 "is typically metallic. The wear sleeve 54 may be formed of metal or ceramic or the like, and the wear sleeve 54 may be hardened prior to use. In some examples, wear sleeve 54 is formed from yttria stabilized zirconia, alumina, tungsten carbide, silicon nitride, and the like. The wear sleeve 54 may therefore be formed of a harder material than the metal of the piston rod 52 "so that the wear sleeve 54 is better able to withstand the frictional forces experienced during pumping. In examples where the wear sleeve 54 is formed of a metal, the metal of the wear sleeve 54 may be different than the metal of the piston rod 52 "and/or may be treated (e.g., heat treated) to have different properties than the piston rod 52". Where wear sleeve 54 is the only portion of piston 50 "that is in contact with dynamic seal 86a, piston rod 52" may be formed of a softer metal and/or may be subjected to less hardening than is typically required to withstand the grinding experienced during pumping. In some examples, wear sleeve 54 is made of the same material as piston rod 52 ". However, it should be understood that regardless of the material from which the wear sleeve 54 is made, the wear sleeve 54 is the only portion of the piston 50 "that engages the dynamic seal 86a during operation.

The wear sleeve 54 provides significant advantages. Wear sleeve 54 experiences all of the frictional forces caused by the reciprocating motion of piston 50 "relative to dynamic seal 86 a. Since the wear sleeve 54 is the only portion of the piston 50 "that is subject to wear generated during reciprocation, the piston rod 52" may be formed of a softer metal and/or may experience less hardening, thereby reducing manufacturing costs. Further, the wear sleeve 54 can be easily removed and replaced on the piston rod 52 "by unscrewing the piston cap 88" from the piston rod body 90 ", pulling the wear sleeve 54 out of the piston rod body 90", and replacing a new wear sleeve 54 on the piston rod body 90 ". The wear sleeve 54 is removable, which saves cost and reduces the downtime previously required to replace the wear elements of the piston 50 ". Wear sleeve 54 eliminates the need to replace piston rod 52 ", thereby reducing operating costs.

Fig. 6A is an exploded view of the piston 50 "'. The piston 50 "'includes a piston rod 52"' and a wear sleeve 54. Plunger rod 52 "'includes plunger cap 88"', plunger rod body 90 "'and plunger head 92"'. Wear sleeve 54 includes a sleeve body 94, a first end 96 and a second end 98. The piston cap 88 "' includes a cap shoulder 102" ' and a connecting portion 104 "'. Piston rod body 90 "'includes a socket 100"', an upstream end 106 "', and a downstream end 108"'. The piston head 92 "'includes a shank 112"', a central bore 114 "', a flange 116"', a head shoulder 118 "', and a piston port 146"'. The handle 112 "'includes a sealing groove 110"'.

Piston rod body 90 "' is integral with piston cap 88" ' and extends longitudinally from piston cap 88 "'. A connecting portion 104 "' is provided on the piston cap 88" ' and is configured to engage with a drive member, such as the reciprocating drive 20, to facilitate reciprocating movement of the piston 50 "' during operation. In the example shown, the connecting portion 104 "'includes an aperture extending therethrough configured to receive a pin to drive the piston 50"' in a reciprocating manner. Cap shoulder 102 "' extends radially from piston cap 88" ' relative to piston rod body 90 "'. Cap shoulder 102 "' is disposed near downstream end 108" ' of piston rod body 90 "'. The socket 100 "' extends into an upstream end 106" ' of the piston rod body 90 "'. In some examples, the socket 100 "' includes internal threads.

A handle 112 "'extends from the downstream end of the piston head 92"'. In some examples, the handle 112 "'includes external threads configured to mate with internal threads of the socket 100"'. As such, the shank 112 "may be threadably engaged into the socket 100" to secure the piston head 92 "to the piston rod body 90". The sealing groove 110 "'extends circumferentially around the handle 112"'. The seal 144 is at least partially disposed in the seal groove 110 "'. The central bore 114 "'extends into the upstream end of the piston head 92"'. Piston port 146 "' extends through piston head 92" ' and is in fluid communication with central bore 114 "'. The piston port 146 "'provides a flow path for fluid to flow downstream out of the piston head 92"'. A flange 116 "' extends radially from the piston head and is configured to support a seal, such as dynamic seal 86B (shown in fig. 2B and 5A). A head shoulder 118 "' extends radially from the piston head 92" ' relative to the piston rod body 90 "'.

Cap shoulder 102 "'and head shoulder 118"' define a cylindrical taper 142 "'that extends along the length of piston rod body 90"' between piston cap 88 "'and piston head 92"'. The wear sleeve 54 is disposed in the cylindrical cutback 142' ″. Sleeve body 94 is cylindrical and surrounds piston rod body 90 "'. The first end 96 of the wear sleeve 54 abuts the head shoulder 118 "', and the second end 98 of the wear sleeve 54 abuts the cap shoulder 102"'. With wear sleeve 54 mounted on piston rod 52 "', piston rod 52"' has a uniform outer diameter between piston cap 88 "', wear sleeve 54 and piston head 92"'. Wear sleeve 54 surrounds piston rod body 90 "'such that piston rod body 90"' is prevented from contacting abrasive wear surfaces, such as dynamic seal 86a, during operation. The wear sleeve 54 is a replaceable wear part of the piston 50' ". As described above, the wear sleeve 54 may be made of any desired material, such as metal or ceramic.

The wear sleeve 54 is mechanically secured to the piston rod 52 "' by the clamping force exerted on the wear sleeve 54 by the head shoulder 118" ' and the cap shoulder 102 "'. The wear sleeve 54 is fixed to the piston rod 52 "' without the use of an adhesive. Mechanically securing the wear sleeve 54 facilitates removal and replacement of the wear sleeve 54. To remove the wear sleeve 54 from the piston rod 52 "', the piston head 92" ' is rotated relative to the piston rod body 90 "' to unscrew the handle portion 112" ' from the socket 100 "'. The piston head 92 "'is pulled out of the piston rod body 90"'. With the piston head 92 "'removed, the wear sleeve 54 is pulled out of the piston rod body 90"'. To install the wear sleeve 54 on the piston rod 52 ", the wear sleeve 54 is slid onto the piston rod body 90". The piston head 92 "' is attached to the piston rod body 90" by threading the shank 112 "' into the socket 100" '. With piston head 92 "'reattached to piston rod body 90"', wear sleeve 54 is secured between head shoulder 118 "'and cap shoulder 102"'.

While the invention has been described with reference to 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 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 disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.