Negating check valve

A positive displacement pump for dispensing fluid includes a fluid body sub-assembly including a fluid body and a negating check valve. The negating check valve includes a negating body defining a dispensing opening. The fluid body and the negating body form a flow path for the fluid. The fluid is dispensed through the dispensing opening. The positive displacement pump is primed by allowing trapped air within the flow path to flow out of the dispensing opening. The negating check valve may be fully or partially attached to the fluid body. The trapped air within the flow path flows out of the dispensing opening when the negating check valve is partially attached to the fluid body.

TECHNICAL FIELD

The present invention relates generally to positive displacement pumps for adhesive dispensing.

BACKGROUND

Traditional positive displacement pumps dispense fluids and/or adhesives by displacing a fixed amount of fluid trapped within a displacement chamber of a positive displacement pump's flow path. Air may become trapped inside the pump's displacement chamber and other parts of the pump's flow path and interfere with the pump's ability to dispense adhesive accurately. One approach to remove trapped air is through bleed holes. However, the bleed holes can get plugged by the adhesive, are messy and provide a low level of confidents that all the trapped air has been removed from the pump's flow path.

SUMMARY

A positive displacement pump for dispensing fluid includes a fluid body sub-assembly including a fluid body and a negating check valve. The negating check valve includes a negating body defining a dispensing opening. The fluid body and the negating body form a flow path for the fluid. The fluid is dispensed through the dispensing opening. The positive displacement pump is primed by allowing trapped air within the flow path to flow out of the dispensing opening.

These and other objects, features and advantages of the present disclosure will become apparent in light of the following description of exemplary embodiments, with reference to the accompanying drawings.

DETAILED DESCRIPTION

Referring toFIG. 1, a positive displacement pump10includes a fluid body sub-assembly12that forms a flow path14through which pressurized fluid is dispensed in the direction shown by arrows18and20. The positive displacement pump10may further include a cylinder sub-assembly22connected to the fluid body sub-assembly12. The cylinder sub-assembly22facilitates the dispensing of the pressurized fluid by displacing the pressurized fluid in the flow path14.

Referring toFIGS. 1-6, the fluid body sub-assembly12includes a fluid body24that defines the flow path14and a negating check valve28attached to the fluid body24that dispenses the pressurized fluid. The fluid body sub-assembly12further includes a barbed fitting hose connector30fluidly connected to the fluid body24. The barbed fitting hose connector30penetrates the fluid body24and defines the beginning of the flow path14through the fluid body sub-assembly12. A flanged locking sleeve32fits over the barbed fitting hose connector30and attaches to the fluid body24. The fluid body sub-assembly12further includes a valve coupling34that fits over the fluid body24and secures the fluid body sub-assembly12to the cylinder sub-assembly22. The fluid body sub-assembly12further includes a tip retainer nut38. The barbed fitting hose connector30, the fluid body24and the negating check valve28form the flow path14.

As shown in more detail inFIGS. 7 and 8, the barbed fitting hose connector30forms the beginning of the flow path14, receives pressurized fluid, and directs the received pressurized fluid into the fluid body24.

The fluid body24has an elongated hollow shape that includes an interior surface40and an exterior surface42that define a first fluid opening44and a second fluid opening48disposed at opposite ends of a longitudinal axis50of the fluid body24. The fluid body24may be fabricated from plastic, metal, or a composite thereof. The second fluid opening48of the fluid body24has a fluid-mating portion52formed on the interior surface40of the fluid body24. The fluid-mating portion52extends along the interior surface40of the fluid body24from the second fluid opening48towards the first fluid opening44. The fluid body24further includes a fitting port54disposed between the first fluid opening44and the second fluid opening48and receives the barbed fitting hose connector30. The fitting port54allows the barbed fitting hose connector30to penetrate the fluid body24. The fluid body24further includes a flooded-product chamber58disposed within the fluid body24between the first fluid opening44and the second fluid opening48. The flooded-product chamber58is fluidly connected to the barbed fitting hose connector30. The fluid body24further includes a sealing displacement chamber60disposed within the fluid body24between the first fluid opening44and the second fluid opening48and downstream from the flooded-product chamber58. The sealing displacement chamber60is fluidly connected to the flooded-product chamber58and the negating check valve28. The flooded-product chamber58and the sealing displacement chamber60form part of the flow path14.

The fluid body24further includes an displacement rod fluid seal62, disposed between the flooded-product chamber58and the sealing displacement chamber60, as well as a fluid chamber seal64, disposed between the first fluid opening44and the flooded-product chamber58. The fluid body24further includes a piston rod bearing68disposed between the fluid chamber seal64and the first fluid opening44.

The flooded-product chamber58may be defined by the interior surface40of the fluid body24and includes a first flooded opening70, a second flooded opening72and a third flooded opening74. The first flooded opening70is fluidly connected to the barbed fitting hose connector30and the second flooded opening72is fluidly connected to the sealing displacement chamber60. The second flooded opening72and the third flooded opening74are disposed on opposite sides of the flooded-product chamber58. The third flooded opening74is configured to receive a displacement rod76that passes through the first fluid opening44of the fluid body24, the piston rod bearing68, the fluid chamber seal64and the flooded-product chamber58, as best seen inFIG. 1. The interior of the flooded-product chamber58is larger than the diameter of the received displacement rod76. Thus, pressurized fluid can flow from the barbed fitting hose connector30, around the received displacement rod76, and into the flooded-product chamber58.

The sealing displacement chamber60includes a sealing opening80and a chamber gateway opening82. The sealing opening80of the sealing displacement chamber60is fluidly connected to the second flooded opening72of the flooded-product chamber58. The chamber gateway opening82of the sealing displacement chamber60is fluidly connected to the negating check valve28. An internal retaining ring81may secure the sealing displacement chamber60to the fluid body24. The sealing displacement chamber60retains pressurized fluid to be dispensed by the negating check valve28. The sealing displacement chamber60further includes an O-ring84disposed near the chamber gateway opening82that fluidly seals off the flow path14from the fluid-mating portion52of the fluid body24.

The displacement rod fluid seal62includes one or more O-rings88. The displacement rod fluid seal62allows pressurized fluid to flow from the flooded-product chamber58to the sealing displacement chamber60. The displacement rod fluid seal62further allows the displacement rod76to pass through and penetrate the sealing displacement chamber60, as best seen inFIG. 17. The displacement rod fluid seal62prevents pressurized fluid from flowing from the flooded-product chamber58to the sealing displacement chamber60while the displacement rod76is penetrating the sealing displacement chamber60.

The fluid chamber seal64includes an O-ring90. The fluid chamber seal64allows the displacement rod76to pass through and penetrate the flooded-product chamber58while preventing the pressurized fluid from flowing out of the third flooded opening74of the flooded-product chamber58.

The piston rod bearing68includes an O-ring92disposed around the exterior of the piston rod bearing68.

The negating check valve28includes a negating body94that has a negating opening98and a dispensing opening100disposed at opposite ends of the negating body94. The negating body94defines a portion of the flow path14. The negating opening98has a negating-mating portion102that extends along the exterior of the negating body94from the negating opening98towards the dispensing opening100. The dispensing opening100terminates the flow path14and dispenses the pressurized fluid therefrom. The negating check valve28further includes a compression spring104disposed within the negating body94between the negating98and dispensing openings100, a ball seat108disposed within the negating body94between the negating opening98and the compression spring104, and a ball110disposed within the negating body94between negating opening98and the ball seat108. The compression spring104exerts force upon the ball seat108and the ball110.

The negating check valve28is attached to the fluid body24by mating the negating-mating portion102of the negating opening98of the negating check valve28with the fluid-mating portion52of the second fluid opening48of the fluid body24. When the negating check valve28is attached to the fluid body24, the negating opening98of the negating check valve28penetrates the second fluid opening48of the fluid body24and the chamber gateway opening82of the sealing displacement chamber60penetrates the negating opening98of the negating check valve28. Further, the negating opening98of the negating check valve28is fluidly connected to the chamber gateway opening82of the sealing displacement chamber60and the O-ring84of the sealing displacement chamber60seals the flow path14so that pressurized fluid cannot flow into the negating-mating portion102and the fluid-mating portion52. The negating check valve28may be fully or partially attached to the fluid body24.

As shown inFIG. 8, when the negating check valve28is fully attached to the fluid body24, the compression spring104is compressed and generates a force that lodges the ball110into the ball seat108and against the chamber gateway opening82of the sealing displacement chamber60. When the ball110is lodged into the ball seat108such that the ball110is against the chamber gateway opening82of the sealing displacement chamber60, the flow path14is blocked and the pressurized fluid cannot flow out of the dispensing opening100of the body94of the negating check valve28.

As shown inFIG. 9, when the negating check valve28is partially attached to the fluid body24, the compression spring104is relaxed such that the force generated by the compression spring104is less than the force generated by the compression spring104when the negating check valve28is fully attached to the fluid body24. When the compression spring104is relaxed, the pressurized fluid entering through the barbed fitting hose connector30is able to flow along the flow path14, around the ball110, and out from the dispensing opening100of the negating check valve28, as the spring104does not provide sufficient pressure or resistance on the ball110to prevent the pressurized fluid from flowing around the ball110.

Referring toFIGS. 1 and 10-14, the cylinder sub-assembly22includes a cylinder housing112and the displacement rod76. The cylinder housing112propels and retracts the displacement rod76. The cylinder sub-assembly22further includes a first114and a second118pneumatic fitting connected to the cylinder housing112which direct pneumatic fluid and/or gas into the cylinder housing112. The cylinder sub-assembly22further includes a stroke adjustor120that determines the distance the displacement rod76is propelled and retracted by the cylinder housing112. The cylinder sub-assembly22may further include a valve-mounting bracket122attached to the cylinder housing112.

As shown in more detail inFIGS. 15 and 16, the cylinder housing112forms an interior cavity124and an exterior surface128and includes a first housing opening130and a second housing opening132disposed at opposite ends of the cylinder housing112along a longitudinal axis134. The cylinder housing112may be fabricated from plastic, metal or a composite thereof. The cylinder housing112further includes a cylinder piston138and a piston rod140both disposed within the interior cavity124. The piston rod140connects the displacement rod76to the cylinder piston138. The cylinder housing112further includes a first and a second pneumatic fitting ports142,144disposed between the first and the second housing openings130,132. The first and second pneumatic fitting ports142,144fluidly connect the first and second pneumatic fittings114,118, respectively, to the interior cavity124. The cylinder housing further includes one or more O-rings148, an airport insert150, a stroke hub152and an internal retaining ring154disposed within the interior cavity124. One or more external retaining rings158and a shim160are mounted to the interior cavity124of the cylinder housing112.

The first and the second pneumatic fittings114,118direct the flow of a pneumatic fluid and/or gas (not shown) into the interior cavity124of the cylinder housing112. The first114and the second118pneumatic fittings are attached to the first and the second pneumatic fitting ports142,144such that the pneumatic fluid and/or gas does not leak out at the first and the second fitting ports.

The mounting bracket122is attached to the cylinder housing112by a first fastener162, e.g., a screw, adhesive(s), soldering or welding. The mounting bracket122may include additional fasteners164for attaching the mounting bracket122to a structure (not shown). The additional fasteners164may be, for example, screws, adhesive(s), soldering or welding.

The displacement rod76penetrates the first fluid opening44of the fluid body24and is received by the third flooded opening74of the flooded product chamber58. The cylinder piston138moves along the longitudinal axis134of the cylinder housing112between a first position, as best seen inFIG. 1, and a second position, as best seen inFIG. 17. The displacement rod76and/or the piston rod140may be guided by the one or more external retaining rings158and the shim160. When the cylinder piston138is in the first position, the displacement rod76is clear of the sealing opening80of the sealing displacement chamber60. When the cylinder piston138is in the second position, the displacement rod76penetrates the sealing displacement chamber60.

The stoke adjustor120abuts the first housing opening130of the cylinder housing112and receives the piston rod140. The stoke adjustor120determines how far the displacement rod76penetrates the sealing displacement chamber60. The stroke adjustor120may include socket head screws168to adjust position of the displacement rod76.

In operation, during operational dispensing mode of the positive displacement pump10, the negating check valve28is fully attached to the fluid body24and pressurized fluid is fed into to the barbed fitting hose connector30. The pressurized fluid then flows along the flow path14and into the flooded-product chamber58. Pressurized pneumatic fluid and/or gas (not shown) is fed into the first pneumatic fitting114which directs the pressurized pneumatic fluid and/or gas into the interior cavity124of the cylinder housing112where it causes the cylinder piston138to move into the first position. When the cylinder piston138is in the first position, the displacement rod76is clear of the sealing opening80of the sealing displacement chamber60. Accordingly, pressurized fluid flows along the flow path14and into the sealing displacement chamber60.

When the negating check valve28is fully attached to the fluid body24, the compression spring104provides sufficient force to prevent the pressurized fluid from flowing around the ball110. Thus, the pressurized fluid is prevented from flowing into the negating check valve28.

After pressurized fluid has filled the sealing-displacement chamber60, the positive displacement pump10may be primed so as to remove any air trapped within the flow path14. Priming is accomplished by loosening the negating check valve28from the fluid body24of the fluid body sub-assembly12until the negating check valve28is partially attached to the fluid body24. When the negating check valve28is partially attached to fluid body24, trapped air in the flow path14can escape via the dispensing opening100of the negating body94of the negating check valve28.

As shown inFIG. 9, the negating check valve28is partially attached to the fluid body24such that the compression spring104has relaxed to the point where the pressurized fluid and the trapped air flow around the ball110, along the flow path14, and out of the dispensing opening100of the negating body94of the negating check valve28. Thus, as the pressurized fluid enters the barbed fitting hose30and passes through the flooded-product chamber58and sealing displacement chamber60, the fluid flows past the ball110since the spring104does not provide sufficient pressure or resistance on the ball110to prevent the pressurized fluid from flowing around the ball110. Therefore, the pressure of the fluid entering the flow path14through the barbed fitting hose30is the same as when the pressurized fluid exists through the dispensing opening100of the negating check valve28. Further, the negating body94may be attached to the fluid body24at a variable degree of attachment having a maximum degree when the negating check valve28is fully attached to the fluid body24. Accordingly, the rate of flow of the pressurized fluid through the flow path14during priming can be varied by varying (tightening/loosening) the degree of attachment of the negating body94of the negating check valve28to the fluid body24. The greater the degree of attachment of the negating check valve28to the fluid body24, the slower the flow of the pressurized fluid through the flow path14. Likewise, the lesser the degree of attachment of the negating check valve28to the fluid body24, the greater the flow of the pressurized fluid through the flow path14.

The pressurized fluid is allowed to continuing flowing out of the dispensing opening100of the negating body94of the negating check valve28until the trapped air has been removed from the flow path14. Further, the flow path14remains sealed while the negating check valve28is partially attached to the fluid body24during the priming of the positive displacement pump10. Thus, the pressurized fluid is unable to flow into the negating-mating portion102or the fluid-mating portion52when the fluid body sub-assembly12is primed.

As shown inFIG. 1, when the trapped air has been removed from the flow path14, the negating check valve28is then fully attached to the fluid body sub-assembly12and the compression spring104generates predetermined force to prevent the pressurized fluid from flowing around the ball110. Accordingly, the pressurized fluid is prevented from flowing into the negating check valve28and thus fills the flooded product chamber58and the sealing displacement chamber60.

Referring toFIG. 17, once the positive displacement pump10has been primed, pressurized pneumatic fluid and/or gas (not shown) is fed into the second pneumatic fitting118and travels down into the interior cavity124of the cylinder housing112to cause the cylinder piston138to move to the second position. When the cylinder piston138is in the second position, the displacement rod76penetrates the sealing displacement chamber60, acting against the pressurized fluid within the sealing displacement chamber60. The displacement rod fluid seal62prevents any pressurized fluid from flowing from the flooded product chamber58into the sealing displacement chamber60while the displacement rod76is penetrating the sealing displacement chamber60.

When the displacement rod76acts up against the pressurized fluid within the sealing displacement chamber60, the force overcomes the compression spring104and the pressurized fluid flows around the ball110. The pressurized fluid then flows into the negating check valve28along the flow path14until it is dispensed out of the dispensing opening100of the negating body94of the negating check valve28.

The degree of the penetration of the displacement rod76into the sealing displacement chamber60, as determined by the stroke adjustor120, determines the amount of the pressurized fluid dispensed from the dispensing opening100of the negating check valve28. For example, the stoke adjustor120can be set so that the positive displacement pump10dispenses small drops of pressurized fluid in variable discrete amounts. The variable discrete amounts may range in size according to the type of pressurized fluid in the flow path14. For instance, the variable discrete amounts may range between 0.0015 grams to 0.015 grams, but other ranges are possible too.

The negating check valve28of the present application is particularly advantageous. For example, by allowing trapped air to flow through the dispensing opening100of the negating body94of the negating check valve28, the fluid body sub-assembly12can be quickly and safely primed with no air remaining trapped within the flow path14.

Further, because the negating check valve28can prime the fluid body sub-assembly12without the need of an additional bleed hole and/or threaded plug, there is no risk of the additional bleed hole becoming clogged. This is particularly useful when the pressurized fluid is an adhesive that may permanently plug the bleed hole.

Additionally, because the flow path14remains sealed even when the negating check valve28is partially attached to the fluid body24, the pressurized fluid does not leak into the negating-mating portion102or the fluid-mating portion52. This is especially advantageous when the pressurized fluid is an adhesive, as there is no risk that the negating check valve28will become permanently bonded to fluid body24. Accordingly, the negating check valve28requires less maintenance than other types of valves.

Although this invention has been shown and described with respect to detailed embodiments thereof, it will be understood by those skilled in the art that various changes in form and detail thereof may be made without departing from the spirit and the scope of the invention.

For example, the fluid body sub-assembly12and the cylinder sub-assembly22may be integrated as a single assembly unit. Additionally, the fittings114and118may be integrated into the cylinder housing112so as to form a single unit. Further, the displacement rod fluid seal62may be integrated into the sealing displacement chamber60. Further still, the ball110may be a generic Teflon ball or any other suitable type of ball. Also, the fluid chamber seal64may be integrated into the piston rod bearing68. Moreover, the pressurized fluid may be a non-compressible fluid. Additionally, the negating-mating portion102and the fluid-mating portion52may be any type of mating system such as magnets, interlocking groves, and/or snap-in connectors. For example, as shown in the figures, the negating-mating portion102may be a threaded and/or grooved portion and the fluid-mating portion52may be a threaded and/or grooved portion and the negating-mating portion102may be mated with the fluid-mating portion52by screwing/securing the negating-mating portion102into the fluid-mating portion52.

Further, it is also to be understood that the terminology used is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the claims of the present application.