Fluid pump leakage transfer

Abstract

Embodiments of the present disclosure relate to fluid pump leakage diversion. A piston rod assembly includes a piston rod having a first end configured to contact a fluid, a packing retainer through which the piston rod extends, and one or more packing rings. The packing retainer includes one or more leakage ports that form a passageway between an inner surface and an outer surface of the packing retainer. The one or more packing rings surround the piston rod, are adjacent to the inner surface of the packing retainer, and are positioned between the one or more leakage ports and a bottom end of the packing retainer. The one or more leakage ports are positioned such that fluid leaking through the one or more packing rings will flow through the one or more leakage ports.

Description

[0001] This application is a divisional application of Chinese patent application No. 201710063467.4, filed on February 3, 2017, entitled "Fluid Pump Leakage Transfer".

[0002] Cross-references to related applications

[0003] This application claims the benefit of U.S. Provisional Application Serial No. 62 / 292,047 entitled “FLUID PUMP LEAKAGE DIVERSION”, filed on February 5, 2016, the disclosure of which is incorporated herein by reference in its entirety. Technical Field

[0004] This disclosure generally relates to fluid distribution systems, and more specifically, to piston pump assemblies for fluid distribution systems. Background Technology

[0005] Fluid distribution systems can be used to spray materials such as paint onto desired surfaces. Fluid distribution systems, such as paint spraying apparatus, typically include a pump assembly to move paint from a reservoir to a spray gun. A piston pump assembly may include a piston rod assembly having a piston rod located within a filler retainer.

[0006] During pumping operation, paint within the piston pump assembly may be forced into the packing retainer and further leak along the piston rod. In this case, the leaking paint may travel along the piston rod until it reaches critical drive mechanisms of the paint spraying unit, such as gears and motors. Such paint leakage can cause damage to critical drive mechanisms, potentially leading to a malfunctioning spraying unit. Therefore, a piston pump assembly is needed that simplifies the identification of paint leaks and prevents leaking paint from contacting and damaging critical drive mechanisms of the paint spraying unit. Summary of the Invention

[0007] A piston rod assembly includes a piston rod having a first end configured to contact a fluid; a packing retainer through which the piston rod extends; and one or more packing rings. The packing retainer includes one or more leakage ports forming a channel between an inner surface and an outer surface of the packing retainer. One or more packing rings surrounding the piston rod are adjacent to the inner surface of the packing retainer and positioned between the one or more leakage ports and a bottom end of the packing retainer. The one or more leakage ports are positioned such that fluid leaking through the one or more packing rings will flow through the one or more leakage ports.

[0008] A method for controlling leakage of fluid along the piston rod of a piston pump assembly, the method comprising: directing fluid leaking through one or more packing rings in a packing retainer from an inner end of a leak port in the packing retainer to an outer end of the leak port, the leak port being located between the one or more packing rings and the top of the packing retainer; directing the fluid from the outer end of the leak port to an inner end of a leak outlet in a pump housing; and directing the fluid from the inner end of the leak outlet in the pump housing to the outer end of the leak outlet, the leak outlet being positioned such that fluid will flow downward along a visible outer surface of the pump housing. Attached Figure Description

[0009] Figure 1 It is a perspective view of the spraying device, in which the door is in the closed position covering the piston pump assembly of the spraying device.

[0010] Figure 2 It is an enlarged partial perspective view of the spraying device, showing the open position of the piston pump assembly mounted on the end bell.

[0011] Figure 3 This is a perspective view of the rear of the piston pump assembly after it has been removed from the end cap.

[0012] Figure 4 This is a cross-sectional view showing the front side of the piston pump assembly inside the pump housing.

[0013] Figure 5 This is a perspective view of the piston rod assembly, which includes the piston rod and the packing retainer.

[0014] Figure 6 It is along Figure 3 The enlarged partial cross-sectional view of the piston pump assembly taken from line 6-6. Detailed Implementation

[0015] In general, this disclosure describes a piston pump assembly that utilizes a leak port and a leak outlet to control the leakage of paint along the piston rod of the piston pump assembly, thereby preventing interference with or damage to the operation of critical drive mechanisms of the paint spraying apparatus. Paint exiting the leak outlet serves as a visible indicator when the piston pump assembly requires maintenance. As a result of controlled leakage and visible indication, the less expensive components of the piston pump assembly can be replaced before other, more expensive components of the paint spraying apparatus fail and require replacement.

[0016] Figure 1This is a perspective view of the spraying apparatus 10, which includes an end bell 12, a frame 14, a front cover 16, a motor housing 18, a piston pump assembly 20, and a feed hose 22. The front cover 16 includes a door 24, which is in a closed position to cover a portion of the piston pump assembly 20 of the spraying apparatus 10.

[0017] End cap 12 is mounted on frame 14. Front cover 16 is attached to the front side of end cap 12, and motor housing 18 is attached to the rear side of end cap 12. Front cover 16 can be secured to the front side of end cap 12 using a plurality of screws extending through front cover 16 and screwed into end cap 12. Piston pump assembly 20 can be mounted to the front side of end cap 12. Feed hose 22 is attached to the bottom end of piston pump assembly 20. Door 24 is movably attached to the bottom end of front cover 16. In an alternative embodiment, front cover 16 may not include door 24. In this embodiment, front cover 16 extends over the area where door 24 will be located.

[0018] End cap 12 serves as a structural element supporting front cover 16 and motor housing 18 on frame 14. Front cover 16 partially includes, covers, supports, and / or protects various components of spraying apparatus 10. Motor housing 18 contains an electric motor (not shown) to drive piston pump assembly 20. End cap 12 also supports piston pump assembly 20. Piston pump assembly 20 causes feed hose 22 to draw paint from reservoir and deliver it to piston pump assembly 20. Paint is further guided through hose (not shown) out of piston pump assembly 20 to gun assembly (not shown) for spraying onto desired surfaces.

[0019] Figure 2 This is a partial perspective view of the spraying device 10, in which the door 24 is in the open position showing the piston pump assembly 20 mounted on the end cover 12. Figure 3 This is a perspective view of the rear side of the piston pump assembly 20, which has been removed from the end cap 12. Figure 4 This is a cross-sectional view showing the front side of the piston pump assembly 20 inside the pump housing 32. Figure 5 This is a perspective view of the piston rod assembly 30, showing the piston rod 40 and the packing retainer 42. These will be discussed together. Figure 2-5 The spraying device 10 includes an end cap 12 (e.g., ...). Figure 2 (as shown), front cover 16 (as shown) Figure 2 As shown), motor housing 18 (as shown) Figure 2 (as shown), piston pump assembly 20 and yoke 26 (as shown) Figure 2 (As shown). The front cover 16 includes a door 24 (as shown). Figure 2 (As shown). End cap 12 includes pin 28 (as shown). Figure 2 (As shown). The piston pump assembly 20 includes a piston rod assembly 30, a pump housing 32, a pressure control device 34, a start control device 36, and an outlet check valve 37 (as shown). Figure 2 and4 As shown), output port 38 (as shown) Figure 2 and Figure 4 As shown), and inlet check valve 39 (as shown) Figure 4 (As shown). The piston rod assembly 30 includes a piston rod 40 and a packing retainer 42. The pump housing 32 includes a receiver 44, a leakage outlet 46, and a feed inlet 48 (as shown). Figure 3 and 4 As shown), pumping chamber 50 (as shown) Figure 4 As shown), feed housing 52 (in Figure 3 and Figure 4 (As shown in the diagram). The inlet check valve 39 includes a ball 39A (as shown in the diagram). Figure 4 (as shown) and ball guide 39B (as shown) Figure 4 (As shown). The packing retainer 42 includes a leakage port 54 (as shown). Figure 4 and 5 (as shown) and channel 56 (as shown) Figure 4 and 5 (As shown).

[0020] The spraying device 10 has an end cap 12, a front cover 16 attached to the front of the end cap 12, and a motor housing 18 attached to the rear of the end cap 12. The top of a piston pump assembly 20 can be mounted to the front of the end cap 12, near the bottom of the end cap 12. The top of the piston pump assembly 20 is mounted to the front of the end cap 12, inside the front cover 16. A door 24 is movably attached to the bottom end of the front cover 16, near the top of the piston pump assembly 20. A yoke 26 is also connected to the front of the end cap 12, inside the front cover 16. The first end of a pin 28 is connected to the front of the end cap 12, near the bottom of the end cap 12, such that it cantilevered out of the end cap 12. The pin 28 is connected to the end cap 12, below the yoke 26 and inside the door 24 of the front cover 16. The pin 28 can be an integral part of the end cap 12 or fixed to the end cap 12. The pin 28 is not mechanically supported by the front cover 16. The pin 28 can be made of metal.

[0021] The piston pump assembly 20 has a piston rod assembly 30, the bottom end of which is surrounded by a pump housing 32. The bottom end of the piston rod assembly 30 extends into the top of the pump housing 32. The piston rod assembly 30 is at least partially contained within the pump housing 32. A pressure control device 34 is attached to a first side of the pump housing 32, and a start control device 36 is attached to a second side of the pump housing 32. In an alternative embodiment, the piston pump assembly 20 does not include either the pressure control device 34 or the start control device 36, or both. An outlet check valve 37 is located on the front side of the pump housing 32, positioned between the pressure control device 34 and the start control device 36. An outlet port 38 is located on the front side of the pump housing 32, positioned between the pressure control device 34 and the outlet check valve 37. The outlet port 38 is the external terminus of a lateral passage within the pump housing 32. An inlet check valve 39 is located within the pump housing 32.

[0022] The piston rod assembly 30 has a piston rod 40 surrounded by a packing retainer 42. The bottom end of the piston rod 40 extends completely through the cavity of the packing retainer 42 and into the top of the pump housing 32, where it can contact the coating inside the pump housing 32. The top end of the piston rod 40 can be inserted into a yoke 26. The piston rod 40 may be made of a metal such as stainless steel. The packing retainer 42 surrounds the piston rod 40, and the bottom end of the packing retainer 42 extends into the top of the pump housing 32. The inner surface of the packing retainer 42 forms a cavity within which the piston rod 40 reciprocates. The outer surface of the packing retainer 42 is its circumferential outer surface. The outer surface of the packing retainer 42 includes threads that can engage with the internal threads of the pump housing 32, allowing the packing retainer 42 to be threaded into and secured to the pump housing 32. The top end of the packing retainer 42 has a hexagonal feature to facilitate tool-assisted removal of the packing retainer 42 from the pump housing 32. The packing retainer 42 can also be called a packing nut.

[0023] Pump housing 32 has a receiver 44 located at the top of pump housing 32, which is an opening. More specifically, the opening of receiver 44 extends completely through pump housing 32. In an alternative embodiment, the opening of receiver 44 may extend only partially through pump housing 32. Receiver 44 may be an opening whose size and shape correspond to the size and shape of pin 28. A first receiver 44 is located on a first side of pump housing 32, and a second receiver 44 is located on a second side of pump housing 32. Leakage outlet 46 is an opening that extends laterally from the inner surface of pump housing 32 through pump housing 32 to the outer surface of pump housing 32. Leakage outlet 46 is located in pump housing 32, below the top of pump housing 32. A first leakage outlet 46 is located on the first side of the front of pump housing 32, and a second leakage outlet 46 is located on the second side of the front of pump housing 32. A third leakage outlet 46 is located on the first side of the rear of pump housing 32, and a fourth leakage outlet 46 is located on the first side of the rear of pump housing 32. Although four leakage outlets 46 are shown, in alternative embodiments, the pump housing 32 may have any number of leakage outlets 46, including a single leakage outlet 46. The inlet 48 is an opening located at the bottom end of the pump housing 32. The inlet 48 leads to the pumping chamber 50. The pumping chamber 50 is an internal chamber or cylindrical cavity formed by the inner surface of the pump housing 32. The pumping chamber 50 receives the bottom end of the piston rod 40. The pumping chamber 50 is in fluid communication with the outlet 38. The bottom end of the pump housing 32 is the inlet housing 52. The pump housing 32 may be made of aluminum, steel, or any other suitable metal. The inlet check valve 39, having a ball 39A and a ball guide 39B, is positioned in the pumping chamber 50 of the pump housing 32, near the bottom of the pumping chamber 50 and above the inlet housing 52.

[0024] The packing retainer 42 has a circumferentially positioned leakage port 54 surrounding the packing retainer 42. The leakage port 54 is an opening extending laterally through the packing retainer 42 from its inner surface to its outer surface. Thus, the leakage port 54 connects the internal or cavity fluid of the packing retainer 42 to its external or circumferential surface. The leakage port 54 is located between the top and bottom ends of the packing retainer 42. Additionally, when the packing retainer 42 is threaded into the pump housing 32, the leakage port 54 is inside the pump housing 32. A first leakage port 54 is located on a first side of the front of the packing retainer 42, and a second leakage port 54 is located on a second side of the front of the packing retainer 42. A third leakage port 54 is located on a first side of the rear of the packing retainer 42, and a fourth leakage port 54 is located on a second side of the rear of the packing retainer 42. Although four leak ports 54 are shown, in alternative embodiments, the packing retainer 42 may have any number of leak ports 54, including a single leak port 54. The leak ports 54 are evenly arranged around the circumference of the packing retainer 42, with one of the four leak ports 54 spaced every 90 degrees. However, in alternative embodiments, the leak ports 54 may not be evenly arranged. The leak ports 54 are positioned such that they are in fluid communication with the leak outlet 46. The channel 56 is a circumferential channel positioned to fluidly connect the leak ports 54 to the leak outlet 46. The channel 56 is a recess formed in the outer surface of the packing retainer 42. The channel 56 may be semi-annular or fully annular. The upper edge of the channel 56 is above the leak ports 54, and the lower edge of the channel 56 is below the leak ports 54. When the channel 56 is formed in the packing retainer 42, the channel 56 is aligned with the leak outlet 46 or a lateral passage leading to the outlet 38. In alternative embodiments, the packing retainer 42 does not include the channel 56. Furthermore, in alternative embodiments, the channel 56 may be formed in the pump housing 32 ( Figure 6 The recess in the inner surface of the channel 54 (shown in the diagram) fluidly connects the leak port 54 to the leak outlet 46, the outlet 38, or a passage leading to the outlet 38. Thus, when the channel 56 is formed in the pump housing 32, the channel 56 is aligned with the leak port 54. Additionally, both the packing retainer 42 and the pump housing 50 may include the channel 56 to fluidly connect the leak outlet 46 and the leak port 54. The packing retainer 42 may be made of a metal such as brass.

[0025] By threading the receiver 44 onto the pin 28, such that the pin 28 is received within the receiver 44, the piston pump assembly 20 can be mounted to the pin 28, and thus to the front side of the end cap 12. For the piston pump assembly 20 to be mounted to the end cap 12, the top of the piston rod 40 must be inserted into the yoke 26. Similarly, by removing the receiver 44 from the pin 28 and the piston rod 40 from the yoke 26, the piston pump assembly 20 can be removed from the end cap 12. A sliding motion can remove the receiver 44 from the pin 28 and disengage the piston rod 40 from the yoke 26, thus separating the piston pump assembly 20 from the end cap 12. The door 24 can be accessed from the closed position (e.g., Figure 1 Move to the open position (as shown) Figure 2 (As shown). Door 24 is opened by a sliding pivoting action. By moving door 24 to the open position, piston pump assembly 20 can be installed onto or removed from end cover 12 without removing front cover 16. Opening door 24 exposes various mechanical and electrical components of the spraying apparatus 10. Piston pump assembly 20 can be removed from end cover 12 for use with the spraying apparatus 10, and in particular, piston pump assembly 20 can be serviced for maintenance.

[0026] The pump housing 32 supports a pressure control device 34 and a start-up control device 36. The pressure control device 34 controls the pressure regulation of the piston pump assembly 20, and the start-up control device 36 controls the starting of the piston pump assembly 20. The pressure control device 34 may include an electrically driven control device containing a sensor sensitive to the generated paint pressure, a user input for setting the paint pressure (e.g., a rotary knob connected to a potentiometer), and a circuit for closed-loop pressure regulation based on the sensor and user input settings. This circuit may control a motor (not shown) to regulate the pressure, for example, by turning the motor on and off.

[0027] Piston pump assembly 20 is mounted to end cap 12 for spraying paint from spraying device 10. Pump housing 32 can be used as a manifold for paint flow. When piston rod 40 is engaged with yoke 26, piston rod 40 is driven by drive mechanism of spraying device 10 to reciprocate within cavity of filler retainer 42 and pumping chamber 50 of pump housing 32. Reciprocating motion of piston rod 40 between downward and upward directions draws paint from reservoir (not shown) into piston pump assembly 20 through feed hose 22 and ejects paint from piston pump assembly 20 through outlet port 38. Inlet port 48 is connected to feed hose 22 to provide passage for paint to be carried into pump housing 32 through feed housing 52. Paint is drawn upward into pumping chamber 50, where it interacts with inlet check valve 39. Ball 39A, seat, and ball guide 39B of inlet check valve 39 allow paint to flow in only one direction, according to Figure 4The orientation shown is generally upward. During the upward stroke phase of the reciprocating cycle, piston rod 40 moves upward to pull the coating material through inlet check valve 39 and further upward into pump chamber 50. During the downward stroke phase of the reciprocating cycle, piston rod 40 moves downward to push the coating material from pump chamber 50 through the lateral passage within pump housing 32 and outlet check valve 37 to outlet 38. Figure 4 The piston rod 40 is shown in the downward stroke phase of a reciprocating motion cycle. A first end of a hose (not shown) can be connected to an outlet 38, and a second end of the hose can be connected to a spray gun assembly (not shown) to dispense paint onto the desired surface.

[0028] Leakage port 54 forms a passage between the inner surface and the outer surface of the packing retainer 42. Therefore, leakage port 54 provides a passage for leaked paint to travel from the inner surface to the outer surface of the packing retainer 42. Leakage port 54 is directly injected into channel 56 at the outer surface of the packing retainer 42. Therefore, once at the outer surface of the packing retainer 42, the paint can travel along channel 56 to leakage outlet 46. Leakage outlet 46 forms a passage between the inner surface and the outer surface of the pump housing 32. Therefore, leakage outlet 46 provides a passage for paint to move from the inner surface or interior of the pump housing 32 to the outer surface or exterior of the pump housing 32 before reaching the top of the pump housing 32. In this embodiment, leakage port 54 is aligned with leakage outlet 46 such that paint can travel directly from leakage port 54 to leakage outlet 46 without needing to travel along channel 56. In such an embodiment, the packing retainer 42 and pump housing 32 may not include channel 56. In an alternative embodiment, the leak port 54 is not aligned with the leak outlet 46, and the coating travels along the channel 56 in the packing retainer 42 to reach the leak outlet 46. In another embodiment, the leak port 54 is not aligned with the leak outlet 46, and the coating travels along the channel 56A in the pump housing 32 (e.g., Figure 6 (As shown) Proceed to the leak outlet 46.

[0029] Due to the pressure from the reciprocating motion or pumping action of the piston rod 40 within the pump housing 32, paint may leak within the pump housing 32 and seep along the piston rod 40 into the packing retainer 42. For example, paint may be forced or squeezed between the inner surface of the packing retainer 42 and the outer surface of the piston rod 40. Leaked paint may seep along the piston rod 40 and from the top of the piston pump assembly 20 until it reaches the internal mechanical components of the spraying device 10 behind the front cover 16. This leaked paint dries on the mechanical components of the spraying device 10 and interferes with the mechanical operation of the spraying device 10. Furthermore, this leak may be concealed by the front cover 16 and the door 24, making it difficult for the user to easily see the paint interfering with the mechanical components. The leak port 54 allows paint to exit the packing retainer 42 from the side of the packing retainer 42 and limits the extent of paint leakage along the piston rod 40. Specifically, paint that has leaked or been squeezed into the packing retainer 42 may be forced or squeezed from the inner surface of the packing retainer 42 through the leak port 54. Therefore, the paint is discharged from the side of the packing retainer 42, rather than being pushed out of the top of the packing retainer 42, where it could come into contact with and damage the drive mechanism of the spraying device 10. The leaked paint can then travel along the channel 56 until it reaches the leak outlet 46 in the pump housing 32. At the leak outlet 46, the paint is pushed from the inner surface of the pump housing 32 to the outer surface of the pump housing 32.

[0030] As a result, the leaked paint escapes from the pump housing 32 through the leak outlet 46 at the side of the pump housing 32 and flows downward along the outer surface of the pump housing 32. Therefore, by providing a pathway for the leaked paint to exit the interior of the pump housing 32 at the side of the pump housing 32 before reaching the top, the leak outlet 46 prevents the paint from escaping through the top of the piston pump assembly 20. Consequently, less paint travels to the outside of the top of the filler retainer 42 to the drive mechanism of the spraying device 10, resulting in less damage to the drive mechanism of the spraying device 10. As a result, the leak outlet 46 prevents paint from leaking into the end cap 12 of the spraying device 10 (e.g., ...). Figure 1 (as shown) and motor housing 18 (as shown) Figure 1 (As shown) and prevents interference with the mechanical function of the drive mechanism of the spraying device 10. Furthermore, because the leak outlet 46 allows leaked paint to flow downwards along the outer surface or exterior of the pump housing 32, the leak outlet 46 provides a visible indicator that paint is leaking, i.e., paint on the outer surface of the pump housing 32. Therefore, the piston pump assembly 20 can be repaired before leaked paint seeps into the internal drive mechanism of the spraying device 10 and causes damage.

[0031] Figure 6 It is along Figure 3The image shows an enlarged partial cross-sectional view of the piston pump assembly 20 taken from line 6-6. The piston pump assembly 20 includes a piston rod assembly 30 and a pump housing 32. The piston rod assembly 30 includes a piston rod 40, a packing retainer 42, and a spring 58. The pump housing 32 includes a leakage outlet 46 and a passage 56A. The packing retainer 42 includes a leakage port 54 and a passage 56. A sleeve 60, a felt ring 62, a first sealing sleeve 64, a packing ring 66, a second sealing sleeve 68, a retainer 70, and a pressure seal 72 are positioned within the packing retainer 42. The pressure seal 72 includes a U-shaped element 74 and an O-ring 76.

[0032] The piston pump assembly 20 has a piston rod assembly 30 surrounded by a pump housing 32. The bottom end of the piston rod assembly 30 extends into the top of the pump housing 32. The piston rod assembly 30 has a piston rod 40 surrounded by a packing retainer 42. The bottom end of the piston rod 40 extends through the cavity of the packing retainer 42 and the top of the pump housing 32 into the pumping chamber 50 of the pump housing 32. The packing retainer 42 surrounds the piston rod 40, and the bottom end of the packing retainer 42 extends into the top of the pump housing 32. A spring 58 is located on the inner surface of the pump housing 32 and near the bottom end of the packing retainer 42.

[0033] The pump housing 32 has a leakage outlet 46 located within the pump housing 32. The leakage outlet 46 is an opening extending laterally from the inner surface of the pump housing 32 through the pump housing 32 to the outer surface of the pump housing 32. The leakage outlet 46 is located on the side of the pump housing 32, below the top of the pump housing 32. In an alternative embodiment, the pump housing 32 may have any number of leakage outlets 46. The channel 56A is a recess formed in the inner surface of the pump housing 32.

[0034] The packing retainer 42 has a leakage port 54 between the top end and the bottom end of the packing retainer 42. The leakage port 54 is an opening that extends laterally from the inner surface of the packing retainer 42 through the packing retainer 42 to the outer surface of the packing retainer 42. Figure 6 Two leak ports 54 are shown, but in alternative embodiments, the packing retainer 42 may have any number of leak ports 54. The packing retainer 42 has a circumferential channel 56, which is a recess formed in the outer surface of the packing retainer 42. The upper edge of the channel 56 is above the leak ports 54, and the lower edge of the channel 56 is below the leak ports 54. The channel 56 is positioned to fluidly connect the leak ports 54 to a leak outlet 46. The channel 56 may be semi-annular or fully annular. In alternative embodiments, the packing retainer 42 does not include the channel 56.

[0035] Channel 56A is aligned with the leak port 54 in the packing retainer 42. Channel 56A is also aligned with channel 56 in the packing retainer 42, such that channel 56A is in fluid communication with channel 56. Channel 56A is positioned to fluidly connect the leak port 54 to the leak outlet 46. Channel 56A may be semi-annular or fully annular. Alternatively, channel 56A may fluidly connect the leak port 54 to the outlet 38 or a passage in the pump housing 32 leading to the outlet 38. In an alternative embodiment, the pump housing 32 does not include channel 56A.

[0036] The packing retainer 42 has an annular sleeve 60 positioned at the top of the packing retainer 42, adjacent to the inner surface of the packing retainer 42. The sleeve 60 surrounds the piston rod 40. The sleeve 60 may be made of metal. In an alternative embodiment, the packing retainer 42 does not include the sleeve 60. Furthermore, in alternative embodiments, the sleeve 60 is positioned at different locations within the packing retainer 42.

[0037] The packing retainer 42 has a felt ring 62 surrounding the piston rod 40 and positioned adjacent to the inner surface of the packing retainer 42 at the leak port 54. Therefore, the felt ring 62 is located between the piston rod 40 and the leak port 54. The felt ring 62 is a paint-permeable annular ring and may be the only paint-permeable component included within the packing retainer 42. The felt ring 62 is formed of felt or other stranded material. Additionally, the felt ring 62 may be oil-impregnated. The felt ring 62 may be a lubricating ring for lubricating the piston rod 40. The felt ring 62 may include a lateral hole adjacent to the first port. In an alternative embodiment, the packing retainer 42 does not include the felt ring 62. Furthermore, in alternative embodiments, the felt ring 62 is located at different positions within the packing retainer 42.

[0038] The packing retainer 42 has an annular first sealing sleeve 64 at the bottom end of the packing retainer 42, adjacent to the inner surface of the packing retainer 42, and surrounding the piston rod 40. The first sealing sleeve 64 has a convex profile. The first sealing sleeve 64 may be formed of nylon of glass packing or any other suitable polymer. In an alternative embodiment, the packing retainer 42 does not include the first sealing sleeve 64. Furthermore, in alternative embodiments, the first sealing sleeve 64 is located at different positions within the packing retainer 42.

[0039] The packing retainer 42 has an annular packing ring 66 adjacent to the inner surface of the packing retainer 42 and surrounding the piston rod 40. The packing rings 66 are V-shaped and stacked on top of each other. Multiple packing rings form a packing ring stack. The bottom end of the bottom packing ring 66 is adjacent to the top end of the first sealing sleeve 64, such that the V-shaped packing ring 66 engages with the first sealing sleeve 64. The packing rings 66 may include alternating leather and polymer rings. The polymer packing rings 66 may be made of UHMWPE or any other suitable polymer. The packing retainer 42 may have any number of packing rings 66 located therein, including a single packing ring 66. In an alternative embodiment, the packing retainer 42 does not include packing rings 66. Furthermore, in an alternative embodiment, the packing rings 66 are positioned at different locations within the packing retainer 42.

[0040] The packing retainer 42 has an annular second sealing sleeve 68 adjacent to the inner surface of the packing retainer 42 and surrounding the piston rod 40. The second sealing sleeve 68 has a concave profile. The bottom end of the second sealing sleeve 68 is adjacent to the top end of the top packing ring 66, such that the second sealing sleeve 68 engages with the V-shaped packing ring 66. The top end of the second sealing sleeve 68 is adjacent to the bottom end of the felt ring 62. The second sealing sleeve 68 may be formed of brass or any other suitable material. In an alternative embodiment, the packing retainer 42 does not include the second sealing sleeve 68. Furthermore, in an alternative embodiment, the second sealing sleeve 68 is positioned at different locations within the packing retainer 42.

[0041] The packing retainer 42 has an annular retainer 70 adjacent to the inner surface of the packing retainer 42 and surrounding the piston rod 40. The bottom end of the retainer 70 is adjacent to the top end of the felt ring 62. The retainer 70 may be formed of acetal or any other suitable polymer. In an alternative embodiment, the packing retainer 42 does not include the retainer 70. Furthermore, in an alternative embodiment, the retainer 70 is positioned at different locations within the packing retainer 42.

[0042] The packing retainer 42 has an annular pressure seal 72 adjacent to the inner surface of the packing retainer 42 and surrounding the piston rod 40. The bottom end of the pressure seal 72 is adjacent to the top end of the retainer 70. The top end of the pressure seal 72 is adjacent to the bottom end of the sleeve 60. In an alternative embodiment, the packing retainer 42 does not include the pressure seal 72. Furthermore, in an alternative embodiment, the pressure seal 72 is positioned at different locations within the packing retainer 42. The pressure seal is wetted by a felt ring 62. The pressure seal 72 has an annular U-shaped element 74 surrounding an O-ring 76. The U-shaped element 74 and the O-ring 76 may be made of a polymer, rubber, a combination of rubber and polymer, or any other suitable material.

[0043] The piston rod 40 moves vertically relative to the packing retainer 42 and sleeve 60, the felt ring 62 of the packing retainer 42, the first sealing sleeve 64, the packing ring 66, the second sealing sleeve 68, the retainer 70, and the pressure seal 72. The sleeve 60, felt ring 62, first sealing sleeve 64, packing ring 66, second sealing sleeve 68, retainer 70, and pressure seal 72 seal the piston rod 40 to prevent coating movement between the outer surface of the piston rod 40 and the inner surfaces of the sleeve 60, felt ring 62, first sealing sleeve 64, packing ring 66, second sealing sleeve 68, retainer 70, and pressure seal 72. A spring 58 maintains compression of the sleeve 60, felt ring 62, first sealing sleeve 64, packing ring 66, second sealing sleeve 68, retainer 70, and pressure seal 72 within the packing retainer 42. The packing ring 66 expands laterally under compression to seal the piston rod 40 to facilitate the creation of a vacuum. The packing ring 66 also provides a seal below the leak port 54. Felt ring 62 allows paint to wick or penetrate between the strands of felt ring 62. If felt ring 62 is oil-impregnated, paint can penetrate felt ring 62, and the oil on the strands may inhibit the drying of water-based paints. Oil also extends the life of packing ring 66, making the wear of packing ring 66 take longer. In addition, oil lubricates pressure seal 72 to extend the life of pressure seal 72, making the wear of pressure seal 72 take longer. If felt ring 62 has lateral holes, paint can flow laterally from the inside of felt ring 62 to the outside of felt ring 62 without penetrating the material of felt ring 62. Pressure seal 72 provides an additional seal between the inner surface of packing retainer 42 and the outside of piston rod 40.

[0044] The packing ring 66 and piston rod 40 create a vacuum to draw paint into the piston pump assembly 20. Because the felt ring 62 is adjacent to the leak port 54, paint passing through the felt ring 62 exits the packing retainer 42 through the leak port 54. As the only paint-permeable component in the packing retainer 42, the felt ring 62's proximity to the leak port 54 positions the release of paint, allowing most or all of the paint to exit through the leak port 54. A pressure seal 72 prevents paint from seeping further up the piston rod 40 through the pressure seal 72 and leaking out of the top of the packing retainer 42. Instead, the pressure seal 72 pushes paint out of the leak port 54 in the packing retainer 42. Furthermore, because the felt ring 62 lubricates the pressure seal 72, the pressure seal is more durable than the first sealing sleeve 64, the packing ring 66, and the second sealing sleeve 68 located below the leak port 54 and positioned within the packing retainer 42. Due to the nature of the reciprocating piston rod 40 and the abrasive material pumped within the piston pump assembly 20, the felt ring 62, first sealing sleeve 64, packing ring 66, second sealing sleeve 68, retainer 70, and pressure seal 72 wear during use, causing paint to leak through them over time. The packing ring 66 may experience more wear and fail first, leading to paint leakage through it.

[0045] The leak vent 54 prevents the paint from flowing entirely along the piston rod 40, leaving the top of the packing retainer 42, and coming into contact with the mechanical structure of the drive mechanism of the spraying device 10. Instead, the paint is diverted through the leak vent 54 to the outside of the packing retainer 42 and through the leak outlet 46 to the outside of the side of the pump housing 32, thus flowing downwards along the outer surface of the pump housing 32. Because the leak outlet 46 is far from the interior of the drive mechanism of the spraying device 10, paint leakage to the leak outlet 46 does not interfere with the operation of the spraying device 10. Furthermore, paint leakage to the leak outlet 46 is visible to the user and provides an indication of wear and the need for maintenance of the piston pump assembly 20, for example, by replacing one or more of the felt ring 62, first sealing sleeve 64, packing ring 66, second sealing sleeve 68, retainer 70, and pressure seal 72 of the packing retainer 42. Thus, the piston pump assembly 20 can be repaired while the rest of the spraying device 10 (including the gear assembly and motor) remains undamaged.

[0046] While the invention has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of the invention. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of the invention without departing from its essential scope. Therefore, it is intended that the invention be limited to the specific embodiments disclosed, but rather that the invention encompass all embodiments falling within the scope of the appended claims.

Claims

1. A piston rod assembly, comprising: The piston rod has a first end configured to contact the fluid. A packing retainer through which the piston rod extends, the packing retainer including one or more leakage ports forming a passage between an inner surface and an outer surface of the packing retainer; A coating-permeable ring is located on the inner surface of the packing retainer adjacent to the one or more leaks; and One or more packing rings surround the piston rod, adjacent to the inner surface of the packing retainer, and are positioned between the one or more leaks and the bottom end of the packing retainer; The one or more leak ports are positioned such that fluid leaking through the one or more packing rings will flow through the one or more leak ports.

2. The piston rod assembly according to claim 1, wherein, The coating permeable ring is made of felt.

3. The piston rod assembly according to claim 1, wherein, The coating-permeable ring is a lubricating ring.

4. The piston rod assembly according to claim 1, characterized in that, The coating permeable ring is oil-immersed.

5. The piston rod assembly according to claim 1, wherein, The coating-permeable ring includes transverse holes adjacent to the one or more leaks.

6. The piston rod assembly of claim 1, further comprising an annular pressure seal adjacent to the inner surface of the packing retainer and positioned between the one or more leakage ports and the top of the packing retainer.

7. The piston rod assembly according to claim 6, wherein, The one or more leakage outlets are located between the annular pressure seal and the one or more packing rings.

8. The piston rod assembly according to claim 6, wherein, The annular pressure seal includes an O-ring and a U-ring.

9. The piston rod assembly according to claim 6, further comprising: A coating-permeable ring is located on the inner surface of the packing retainer adjacent to the one or more leaks; An annular retainer is located adjacent to the inner surface of the packing retainer and positioned between the annular pressure seal and the coating-permeable ring; A first annular sealing sleeve is located adjacent to the inner surface of the packing retainer and is positioned between the one or more packing rings and the bottom end of the packing retainer; The second annular sealing sleeve is adjacent to the inner surface of the filler retainer and is positioned between the paint-permeable ring and the one or more filler rings; as well as A sleeve is located adjacent to the inner surface of the packing retainer and positioned between the annular pressure seal and the top end of the packing retainer.

10. The piston rod assembly of claim 6, further comprising a spring adjacent to the bottom end of the packing retainer.

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