Fluid circulation valve assembly for fluid proportioner

A fluid circulation valve assembly comprises a valve body and first and second pressure relief valves. The valve body comprises two inlets to receive output of fluid pumps, two outlets to direct fluid from the two inlets out of the valve body, respectively, and two overpressure outlets to direct fluid from the twos out of the valve body, respectively. The first and second pressure relief valves intersect the two inlets, the two outlets and the two overpressure outlets, respectively. Each pressure relief valve comprises a spring operated overpressure valve configured to open an inlet to an overpressure outlet at an overpressure condition; and a manually operated valve having a first position configured to fluidly connect an inlet to an outlet while not affecting operation of the overpressure valve, and a second position configured to fluidly connect an inlet to an overpressure outlet while opening the overpressure valve.

BACKGROUND

The present invention relates generally to plural-component spray systems. In particular, the present invention relates to pressure relief systems for reciprocating fluid proportioners having at least two pumps.

Fluid proportioners comprise dispensing systems that receive separate inert fluid components, mix the components in a predetermined ratio and then dispense the components as an activated compound. For example, fluid proportioners are used to dispense epoxies and polyurethanes that solidify after mixing of a resin component and an activating material, which are individually inert. However, after mixing an immediate chemical reaction begins taking place that results in the cross-linking, curing, and solidification of the mixture. Therefore, the two components are routed separately into the proportioner so that they can remain segregated as long as possible. A manifold receives each component after it is pumped separately and mixes the components so the mixture can be dispensed from a sprayer coupled to the manifold.

A typical fluid proportioner comprises a pair of positive displacement pumps that individually draw in fluid from separate fluid hoppers and pump pressurized fluids to the mix manifold. The pumps are driven in synchronicity by a common motor, typically an air motor or hydraulic motor, having a reciprocating drive shaft. Most two component epoxies and polyurethanes are not, however, comprised of a 1:1 ratio of the components. Typically a first major component is needed in a higher concentration than a second minor component. In such a case, displacement of one pump is required to be larger than the other. The components are routed from the pumps to the mix manifold for blending. Additionally, a fluid manifold is positioned between the pumps and the mix manifold to permit each fluid to be independently circulated by its pump without mixing, thus segregating the mixing and curing part of the spray process from the pumping and pressurization part.

Because the fluids are circulated under high pressure, it is also desirable to provide pressure relief valves throughout the proportioner system. In particular, if one of the fluid lines becomes plugged, or one of the hoppers runs out of fluid, the other functioning pump will take the full force of the drive motor, causing an overpressure condition. For example, if a 4:1 mix ratio proportioner is spraying at 4,000 psi (˜27.6 MPa) and the major component pump runs out of fluid, the minor component pump will develop four times the normal operating pressure, or 16,000 psi (˜110.3 MPa). Excess pressures need to be vented to prevent failure of parts and unsafe conditions.

Typical proportioners include rupture disks that are permanently sealed, but open by tearing or bursting when overpressure conditions occur. Rupture disks can only be used one time and are used as secondary or back-up systems. Once the rupture disk breaks, the proportioner must be taken out of action until the disk can be replaced. Additionally, over pressure relief valves are used as the primary relief system. Relief valves are spring loaded and are set to open at a specific overpressure. The relief valves drain back to the hoppers or drain cans through drain lines. Ideally, the relief valves are not frequently used. As such, the relief valves and lines have a tendency to become plugged by the accumulation of dried and crystallized fluid from the previous use. This causes the relief valves to open at a much higher pressure or, in extreme cases, to not open at all. As such, there is a need to provide proportioners with more reliable and reusable relief valve systems.

SUMMARY

A fluid circulation valve assembly for a fluid proportioner comprises a valve body and first and second pressure relief valves. The valve body comprises first and second inlets to receive output of fluid pumps, first and second outlets to direct fluid from the first and second inlets out of the valve body, respectively, and first and second overpressure outlets to direct fluid from the first and second inlets out of the valve body, respectively. The first and second pressure relief valves intersect the first and second inlets, first and second outlets and first and second overpressure outlets, respectively. Each pressure relief valve comprises a spring operated overpressure valve configured to open an inlet to an overpressure outlet at an overpressure condition, and a manually operated valve having a first position configured to fluidly connect an inlet to an outlet while not affecting operation of the overpressure valve, and a second position configured to fluidly connect an inlet to an overpressure outlet while opening the overpressure valve.

DETAILED DESCRIPTION

FIG. 1is a perspective view of dual pump proportioner system10of the present invention. Proportioner system10is mounted on cart12and includes air motor14, fluid pumps16A and16B, fluid manifold18, mix manifold20and fluid hoppers22A and22B. Air motor14drives pumps16A and16B such that fluid from hoppers22A and22B is mixed in mix manifold20before being dispensed by a spray gun (not shown) coupled to outlet24. High pressure air is provided to system10at air inlet26. A hose (not shown) connects air inlet26to main air control28, which includes a switch or valve for feeding pressurized air to air motor14. Air motor14is mounted to platform30of cart12using mounting plate31. Air motor14comprises any conventional air motor as is known in the art. In other embodiments, a hydraulic motor is used. However, any motor having a reciprocating shaft may be used. As is discussed in detail with reference toFIGS. 2 and 3, pumps16A and16B are supported underneath air motor14such that air motor14can actuate pumps16A and16B. Operation of air motor14causes fluid within hoppers22A and22B to be drawn into pumps16A and16B, respectively, and pushed out to fluid manifold18. Pumps16A and16B comprise conventional positive displacement pumps having reciprocating pump shafts, as are known in the art. Fluid manifold18controls flow of fluid to mix manifold20, keeping the fluid components separated until after pumping. Mix manifold20blends the fluids on their way to outlet24. Fluid manifold18includes pressure gauges32A and32B, which provide an indication of the fluid pressures generated by pumps16A and16B, respectively.

Operation of proportioner system10is discussed with reference toFIGS. 2 and 3. As discussed in detail with reference toFIG. 4, fluid manifold18and mix manifold20together comprise fluid control assembly33. As discussed with reference toFIG. 5, fluid manifold18includes valves that simultaneously provide overpressure relief and drain valves for pumps16A and16B of proportioner system10. Operation of fluid manifold18is explained with reference toFIGS. 6A and 6B.

FIG. 2is a close-up perspective view of a back side of dual pump proportioner system10ofFIG. 1showing support tie rods34A-34D and pump tie rods36A and36D coupling air motor14to pumps16A and16B.FIG. 2shows the rear side of air motor14and pumps16A and16B with respect to the front of system10shown inFIG. 1. Air motor14is coupled to mounting plate31. Tie rods34A-34D are coupled to plate31at their uppermost ends and coupled to pump housings38A and38B at their lowermost ends. Specifically, tie rods34A,34C and36A connect pump housing38A of pump16A to mounting plate31, and tie rods34B,34D and36B connect pump housing38B of pump16B to mounting plate31. Housings38A and38B are coupled together with link40A (shown inFIG. 3), which connects to tie rods34A and34B. Another link40B (FIGS. 2 and 3) is coupled to tie rods34C and34D. Links40A and40B connect adjacent tie rods that are joined to different pump housings. The uppermost ends of tie rods36A and36B are coupled to mounting plate31and the lowermost ends are coupled to pump housings38A and38B, respectively. Tie rods36A and36B extend through yoke42. Bushings44A and44B surround tie rods36A and36B, respectively, within yoke42. Drive shaft46extends from air motor14, through mounting plate31, and couples to yoke42. Yoke42also couples with pump shafts48A and48B of pumps16A and16B, respectively. Reciprocation of pump shafts48A and48B produces flow of fluids into fluid manifold18of fluid control assembly33ofFIGS. 1 and 4.

Drive shaft46reciprocates yoke42, which glides along tie rods36A and36B with the aid of bushings44A and44B, respectively. Yoke42reciprocates pump shafts48A and48B, which cause pumps16A and16B to draw fluid from hoppers22A and22B and to push fluid into fluid manifold18, as discussed with reference toFIG. 1. Tie rods34A-34D and tie rods36A and36B maintain pump housings38A and38B stationary with respect to air motor14and plate31. Yoke42and piston shafts48A and48B reciprocate between mounting plate31and pump housings38A and38B under power from drive shaft46.

FIG. 3is an exploded perspective view of dual pump proportioner system10ofFIGS. 1 and 2. System10includes air motor14and pumps16A and16B. Air motor14is coupled to mounting plate31using motor tie rods50A-50C, and pumps16A and16B are coupled to mounting plate31using support tie rods34A-34D and pump tie rods36A and36B. Mounting plate31includes slots52A-52C, motor opening54, bores56A-56D and bores58A and58B. When assembled, motor tie rods50A-50C extend into slots52A-502C. Tie rods34A-34D are fastened to bores56A-56D, respectively. When assembled, pump tie rods36A and36B are fastened to bores58A and58B, respectively, at their upper ends, and coupled with yoke42at their lower ends. Motor shaft46extends into shaft bore54. Motor shaft46includes extension60and coupler61. Extension60includes head62for coupling with yoke42. Extension60includes nut64and gauge65is fitted around extension60to ride along mounting plate31. When assembled, nut64is tightened down on gauge65to immobilize extension60(and drive shaft46) with respect to yoke42. Tie rods36A and36D extend from bores58A and58B down to yoke42when assembled. Yoke42includes shaft slot66and tie rod bores68A and68B. Tie rods36A and36D pass through bushings44A and44B and bores68A and68B, respectively. Pump tie rods36A and36B couple to pump housings38A and38B, respectively. For example, tie rod36A is secured to flange70A using nut72A. Tie rod36B is similarly secured to a flange (not shown) using nut72B. Likewise, support tie rods34A-34D extend down from mounting plate31to tabs located on pump housings38A and38B and are secured with nuts74A-74D. For example, tie rods34A and34B couple to tabs flanges76A and76B using nuts74A and74B, respectively. Adapters78A and78B of pump shafts48A and48B are joined to couplers on the underside of yoke42. Reciprocation of drive shaft46is achieved by alternating the introduction of pressurized air into opposite sides of a piston within housing80, thus causing yoke42to ride on pump tie rods36A and36B and pump shafts48A and48B to be actuated. Pumps shafts48A and48B produce outflows of fluids from outlets49A and49B, respectively. Pump housings38A also includes rupture disk57A, which provides a fail safe overpressure outlet for pump16A. Typically, rupture disks are only provided on the smaller pump that is more susceptible to overpressure from the motor. Outlets49A and49B are fluidly coupled to fluid control assembly33.

FIG. 4is a perspective view of fluid control assembly33ofFIG. 1showing fluid manifold18and mix manifold20. As shown inFIG. 1, fluid control assembly33is mounted on cart12of proportioner10. In other embodiments, fluid control assembly33can be uncoupled from cart12so as to enable remote operation of proportioner10. Fluid manifold18includes first pressure gauge32A, second pressure gauge32B, valve body82, first drain valve84A, second drain valve84B, first valve lever86A, second valve lever86B, handle88, first outlet90A, second outlet90B, first recirculation or overpressure outlet92A, second recirculation or overpressure outlet92B, plug94A and plug94B (FIG. 5). Mix manifold20includes first shut-off valve96A, second shut-off valve96B, handle98, manifold body100, solvent flush mechanism102and outlet104.

Valve body82of fluid manifold18comprises a block through which various flow paths are machined to connect drain valves84A and84B with outlets90A and90B, outlets92A and92B and plugs94A and94B. Valve body82is provided with fluid from outlets49A and49B of pumps16A and16B (FIG. 3). The fluid is routed through drain valves84A and84B to outlets90A and90B. Levers86A and86B toggle drain valves84A and84B between recirculation mode positions and spray mode positions. Handle88ensures that valves84A and84B are in the same position and switched at the same time. With handle88in the up position as shown inFIG. 4, fluid manifold is in a spray mode. With handle88in a down position, fluid manifold18is in a recirculation mode. Pressure gauges32A and32B indicate the pressure of each fluid within valve body82, as generated by pumps16A and16B, respectively. Outlets92A and92B are coupled to a fluid container to collect fluid circulated out of valve body82. Outlets90A and90B are connected to shut-off valves96A and96B, respectively, of mix manifold20.

Shut-off valves96A and96B provide output control of proportioner system10. Shut-off valves96A and96B provide fluid inputs to mix manifold body100, which combines the individual flows of each fluid into a single, mixed flow that exits mix manifold body100at outlet104. Solvent flush mechanism102allows solvent to be introduced into and flushed from mix manifold20to clean out mixed fluid components before they fully cure and harden. Mix manifold outlet104is coupled to proportioner outlet24(FIG. 1), which couples to a spray gun or any suitable spraying device.

FIG. 5is an exploded view of fluid manifold18ofFIG. 4showing drain valves84A and84B coupled by common actuation handle88. Fluid manifold18includes inlets91A and91B in addition to the elements as listed with respect toFIG. 4. Drain valve84A comprises spring106A, valve stem108A and valve head110A. Likewise, drain valve84B comprises spring106B, valve stem108B and valve head110B.

Inlets91A and91B comprise fittings112A and112B that can be threaded or otherwise coupled to valve body82. Additionally, inlets91A and91B include fittings114A and114B that permit hoses from outlets49A and49B of pumps16A and16B, respectively, to be coupled to fluid manifold18. Outlets90A and90B comprise fitting116A and116B that can be threaded or otherwise coupled to valve body82. Additionally, outlets90A and90B include fittings118A and118B that permit hoses to join outlets90A and90B of fluid manifold18with shut-off valves96A and96B, respectively, of mix manifold20. Recirculation outlets92A and92B comprise fitting120A and120B that can be threaded or otherwise coupled to valve body82. Additionally, recirculation outlets92A and92B include fittings122A and122B that permit hoses to join outlets92A and92B of fluid manifold18with hoppers22A and22B (FIG. 1), respectively, of proportioner system10. Rupture disk57A is also threaded into housing38A of pump16A. Rupture disk57A includes a membrane that bursts when pressures feeding valve body82from pump16A exceed predetermined threshold levels, as is known in the art.

Valves84A and84B are coupled to valve body82at valve heads110A and110B. Valve heads110A and110B are threaded or otherwise coupled to bores in valve body82, respectively. For example, neck124of valve head110A is threaded into bore126such that passages within head110A extend into bore114. Valve heads110A and110B are joined to valve stems108A and108B, respectively, within valves84A and84B. Springs106A and106B are slid over valve stems108A and108B, respectively. Levers86A and86B are positioned on valve stems108A and108B, respectively, to compress springs106A and106B, and secured with nuts116A and116B. Springs106A and106B and cams within valves84A and84B control axial movement of valve heads110A and110B to control fluid flow through outlets92A and92B, while valve stems108A and108B and levers86A and86B control rotational movement of valve heads110A and110B to control fluid flow through outlets90A and90B.

Springs106A and106B bias valve heads110A and110B into positions to block flows from inlets91A and91B to outlets92A and92B, respectively. If pressures within valves84A and84B exceed the spring force of springs106A and106B, outlets92A and92B will be opened. Additionally, levers86A and86B can be rotated to adjust cams within valves84A and84B to manually compress springs106A and106B and open outlets92A and92B. Operation of levers86A and86B also control flow of fluid to outlets90A and90B, respectively. Specifically, levers86A and86B rotate valve stems108A and108B to align porting in head110A and110B to connect inlets91A and91B with outlets92A and92B, respectively, when in the recirculation mode as shown inFIG. 6A. Alternatively, levers86A and86B rotate valve stems108A and108B to align porting in head110A and110B to connect inlets91A and91B with outlets90A and90B, respectively, when in the spray mode as shown inFIG. 6B.

As shown inFIG. 6A, drain valve84A includes fluid control valve head130A and overpressure relief valve132A. Drain valve84B includes fluid control valve head130B and overpressure relief valve132B. Pump16A draws in fluid from hopper22A and provides pressurized fluid to drain valve84A through inlet91A. Inlet91A is coupled to fittings120A and122A, as shown inFIG. 5. Pump16B draws in fluid from hopper22B and provides pressurized fluid to drain valve84B through inlet91B. Inlet91B is coupled to fittings120B and122B, as shown inFIG. 5.

Head130A is oriented to a recirculation position such that passageways134A connect inlet91A to overpressure outlet92A. Oriented as such, head130A interacts with overpressure relief valve132B to permit fluid through overpressure outlet92A. Specifically, head130A includes a cam that opens overpressure relief valve132A by overcoming a spring force that normally maintains valve132A in a closed state. Head130A also closes of flow from inlet91A to outlet90A. Head130B acts upon overpressure relief valve132B in a similar fashion. In other embodiments of the invention, cams may be positioned on other portions of valves84A and84B, such as valve stems108A and108B (FIG. 5). Outlets92A and92B include fittings120A,120B,122A and122B, respectively, shown inFIG. 5.

In such a configuration, fluid is not sent to mix manifold20. Fluid manifold18acts to circulate fluid from hoppers22A and22B out of fluid manifold18. Overpressure outlets92A and92B can be coupled to hoppers22A and22B, respectively, in the recirculation mode. Such a configuration is used to prime pumps16A and16B with component material from hoppers22A and22B. Overpressure outlets92A and92B can be coupled to other fluid containers, cans, bottles or the like to capture fluid circulated from pumps16A and16B through fluid manifold.18. Such a configuration is used to circulate solvent through proportioner10. For example, clean solvent is placed in hoppers22A and22B, circulated through pumps16A and16B where it collects residual material, and dirty solvent is collected in separate fluid containers. Solvent is independently used to clean mix manifold20using solvent flush mechanism102(FIG. 4).

As shown inFIG. 6B, proportioner system10is configured in a spray mode. Specifically, valve heads130A and130B are oriented such that passages134A and134B connect inlets91A and91B to outlets90A and90B, respectively. Outlets90A and90B include fittings116A,116B,118A and118B, respectively, shown inFIG. 5. As such, pumps16A and16B direct fluid from hoppers22A and22B out to mix manifold20. In such a configuration, fluid manifold is susceptible to overpressures from pumps16A and16B. Valve body82is provided with two independent means for overcoming overpressure conditions. First, overpressure relief valves132A and132B are provided in overpressure outlets to92A and92B to vent overpressure from inlets91A and91B. With heads130A and130B oriented as shown inFIG. 6B, cams provided on drain valves84A and84B are rotated by handle88away from overpressure relief valves132A and132B, respectively. As such, springs within overpressure relief valves132A and132B close-off overpressure outlets92A and92B, respectively. However, valves132A and132B are still fluidly coupled to pressurized fluid flowing through inlets91A and91B via passages134A and134B, respectively. If the pressurized fluid overcomes the spring force, valves132A and132B will open, venting excessively pressurized fluid to a separate container coupled to overpressure outlets92A and92B. Overpressure relief valves132A and132B are maintained wetted by operation of fluid manifold18in the priming mode as shown inFIG. 6A. As such, valves132A and132B are lubricated such that they open at the intended overpressure condition. If, however, for some unforeseen reason valves132A and132B do not open as intended, rupture disk57A is provided on pump16A. Rupture disk57A is configured, as is known in the art, to intentionally fail at a predetermined pressure. Below the predetermined pressure, metallic membranes of rupture disk57A seal allow pressurized fluid to continue to flow through outlets90A and90B. At or above the predetermined pressure, the membranes will tear or burst to vent excessively pressurized fluid from pump16A. Typically, the fluid is not, however, contained. Additionally, once ruptured the disk must be replaced. As such, rupture disk57A provides a last resort failsafe. Plugs94A and94B provide access to passages within valve body for maintenance and other purposes.

The present invention provides a system that maintains pressure relief valves wetted within normal operation of the proportioner system. For example, drain valves are rotated to a recirculation position to prime the proportioner pumps by routing fluid through the pressure relief valves. As such, the pressure relief valves remain lubricated to limit exposure to air and to prevent formation of dried and crystallized component fluids. As such, the pressure relief valves remain in good working condition when needed to vent actual over pressure conditions when the drain valves are operating in a spray mode. Additionally, the drain valves are manually operable to provide a pressure dump when spraying is completed, again wetting the pressure relief valves. Thus, when not in the priming or dumping mode, the pressure relief valves have been wetted such that they will readily open during an overpressure events, such as when one fluid is exhausted from a hopper.