HK1094248B - Air foam pump with shifting air piston - Google Patents

Description

Air foam pump with moving air piston

Technical Field

The present invention relates to a manually operated liquid foaming dispenser. In particular, the present invention relates to a manually operated pump that is attached to the top of a bottle containing a liquid and pumps and mixes the liquid and air to generate foam from the liquid and dispense the foam. The dispenser includes a pump housing containing an air pump chamber and a liquid pump chamber, and a pump plunger that manually reciprocates within the air pump chamber and the liquid pump chamber. The air piston and the liquid piston are mounted on the plunger and are reciprocated by the plunger in the respective air pump chamber and liquid pump chamber.

Background

There are various types of manually operated liquid dispensers that pump liquid from a container to which it is connected and generate a foam from the liquid discharged from the dispenser. A common example of these types of foam-producing liquid dispensers is a manually operated trigger sprayer. The trigger sprayer is designed to be held in one hand of a user, and the trigger of the trigger sprayer is easily controlled by the fingers of the user. Pivotal movement of the trigger sprayer operates a liquid pump within the trigger sprayer. Operation of the pump draws liquid from a bottle container attached to the trigger sprayer and discharges the liquid in a spray from a discharge nozzle of the trigger sprayer. The discharge nozzle of this type of trigger sprayer typically has a blockage located in the path of the liquid being sprayed from the trigger sprayer. The liquid spray striking the obstruction mixes the liquid spray with air in the environment outside the sprayer and thereby produces foam that is discharged from the trigger sprayer.

Foaming liquid trigger sprayers of the type described above are well suited for dispensing foam generated from liquids where foaming of the desired liquid is critical, such as foaming liquids for kitchen or bathroom cleaners. But this type of foaming liquid trigger sprayer cannot produce a denser foam such as that in shaving cream.

To produce a denser foam from a manually operated foaming liquid dispenser, both liquid and air need to be pumped through the obstruction that produces the foam. Foaming liquid dispensers of this type include a pump housing containing an air pump chamber and a liquid pump chamber, and a pump plunger that manually reciprocates within the pump housing. An air piston is mounted on the pump plunger and is received for reciprocating movement in the air pump chamber, and a liquid piston is mounted on the pump plunger and is received for reciprocating movement in the liquid pump chamber. Movement of the pump plunger to a retracted position within the pump housing moves the air piston into the air pump chamber and applies a force to air within the chamber and also moves the liquid piston into the liquid pump chamber and applies a force to liquid within the chamber. A pair of valves controls the flow of air and liquid from the respective air and liquid pump chambers through the central discharge passage of the pump plunger where the air and liquid are mixed to create the foam. The foam is then discharged from the dispenser.

The spring of the foaming liquid dispenser moves the pump plunger from its retracted position within the pump housing to an extended position in which the top of the pump plunger extends outwardly from the top of the pump housing. This movement of the pump plunger moves the air piston and the liquid piston out of the respective air pump chamber and liquid pump chamber, expanding the internal volume of both chambers. This creates a vacuum within the two pump chambers that draws air into the interior volume of the air pump chamber and draws liquid into the interior volume of the liquid pump chamber. Because the internal volume of the pumping chamber increases as the pump plunger moves, valve assemblies are typically employed to control the flow of air and liquid into the respective air and liquid pumping chambers. The valves permit air and liquid to enter the respective air and liquid pump chambers when the pump plunger is moved to its extended position, and the valves close to prevent the passage of air and liquid through the valves when the pump plunger is moved to its retracted position within the pump housing.

A considerable number of manually operated foaming liquid dispensers are manufactured to meet the needs of the user. Although the manufacturing costs of a manually operated liquid foaming dispenser are reduced to a small extent, for example 1 cent or a fraction of 1 cent, the manufacturing costs of a manually operated liquid foaming dispenser can be greatly reduced due to the large number of dispensers manufactured. Thus, even variations in the design of manually-operated foaming liquid dispensers that result in a minimal reduction in manufacturing costs would be of great benefit to the manufacture of manually-operated foaming liquid dispensers.

Disclosure of Invention

The manually operated foaming liquid dispenser of the present invention has a novel and simplified construction which reduces the number of component parts compared to prior art dispensers which pump air and liquid when generating foam which is discharged from the dispenser. This novel construction of the foaming liquid dispenser eliminates the need for a valve to control the flow of air into the air pump chamber of the dispenser, thereby eliminating the cost of the valve and reducing the cost of manufacturing the dispenser. In addition, the manually operated liquid foaming dispenser of the present invention has a more simplified construction than other prior art liquid foaming dispensers. This more simplified construction of the dispenser also results in a reduction of manufacturing costs. Furthermore, the novel construction of the liquid foaming dispenser makes it possible to immediately connect the interior of the air pump chamber to the environment outside the dispenser under the action of the upward movement of the pump plunger. This ensures that the air pump chamber is vented even if the user of the dispenser causes the pump plunger to reciprocate rapidly within the pump housing without returning it to a fully extended position relative to the pump housing.

The pump housing of the foaming liquid dispenser of the present invention combines the connecting cover, the air pump chamber and the liquid pump chamber into one integral piece. The liquid pump chamber, the air pump chamber, and the connecting cover have a common central axis and are axially aligned within the pump housing. The cylindrical liquid pump chamber is located at the bottom of the pump housing. An opening on the top of the liquid pump chamber communicates the interior volume of the liquid pump chamber with the cylindrical air pump chamber directly above. The air pump chamber also has an opening at its top that communicates the interior volume of the air pump chamber with the exterior environment of the dispenser through the top opening of the pump housing. The connection cover surrounds the top opening of the pump housing.

A dip tube is connected to the bottom of the pump housing and extends downwardly from the liquid pump chamber. The liquid inlet control valve is disposed at the bottom of the liquid pump chamber. The liquid inlet control valve controls the flow of liquid through the dip tube and into the liquid pump chamber and prevents backflow.

The pump housing is connected to the bottle containing the liquid by first inserting the liquid pump chamber and the air pump chamber through the neck opening of the bottle. The connecting cap is connected to the outside of the bottle neck, and the air pump chamber and the liquid pump chamber are located in the bottle. The dip tube extends downwardly from the pump housing into the liquid contained in the bottle to a position adjacent the bottom of the bottle.

The pump plunger is fitted within the pump housing through a top opening of the pump housing. The pump plunger has a tubular section with an internal discharge passage extending through the section of the pump plunger. A liquid piston is mounted externally of the pump plunger and is received within the liquid pump chamber for reciprocal movement therein. An air piston is also mounted externally of the pump plunger and is received in the air pump chamber for reciprocal movement therein.

The liquid outlet valve is fitted within the interior discharge passage of the pump plunger adjacent the bottom of the plunger. The liquid outlet valve controls the flow of liquid out of the liquid pump chamber and into the discharge passage of the plunger while preventing backflow of the liquid. An air outlet valve is also fitted within the interior discharge passage of the pump plunger at an intermediate position along the passage. An air outlet valve controls the flow of air out of the air pump chamber and into the discharge passage of the plunger while preventing backflow of air.

The spring is fitted between the pump housing and the pump plunger. The spring biases the pump plunger to an extended position of the plunger relative to the pump housing in which a top portion of the pump plunger projects outwardly from a top portion of the pump housing.

The pump plunger includes a dispenser head at the top of the pump plunger. The dispenser head has a tubular central cylinder and a spout, both of which are part of the internal discharge passage of the pump plunger. The central cylinder of the dispenser head and the spout deliver the foam produced by the dispenser and the spout discharges the foam from the dispenser.

Manually pressing the pump plunger into the pump housing compresses the spring and forces the air piston upward into the air pump chamber, reducing the internal volume of the air pump chamber. Downward movement of the pump plunger also causes the liquid piston to move downward into the liquid pump chamber, reducing the internal volume of the liquid pump chamber. Downward movement of the pump plunger causes the air piston to pressurize air within the air pump chamber. The pressurized air unseats the air outlet valve from the valve seat, which allows air from the air pump chamber to enter the interior discharge passage of the pump plunger through the air outlet valve. Downward movement of the pump plunger also causes the liquid piston to apply a force to the liquid in the liquid pump chamber, which unseats the liquid outlet valve. Thereby causing liquid within the liquid pump chamber to be forced through the liquid outlet valve and into the internal discharge passage of the pump plunger. Air and liquid entering the internal passage of the pump plunger pass through the mixing element, which creates foam from the air and liquid. The foam is forced upwardly through the internal discharge passage of the pump plunger and dispensed therefrom.

After the pump plunger completes its movement downwardly into the pump housing to its retracted position within the pump housing, the compressed spring urges the pump plunger to move out of the pump housing toward its extended position relative to the pump housing. This in turn causes the air piston and the liquid piston to move upwardly within the respective air pump chamber and liquid pump chamber, creating a vacuum pressure in each of the chambers. The vacuum pressure in the liquid pump chamber forces the liquid inlet valve off the valve seat, thereby drawing liquid up from the dip tube into the liquid pump chamber.

The novel mechanism of the manually operated foaming liquid dispenser of the present invention does not include a separate valve that opens to vent air into the air pump chamber in response to a vacuum being created in the air pump chamber. Instead, the air piston of the dispenser is configured with a central hole that acts as a vent for the air pump chamber. The pump plunger extends through the vent hole of the air piston. This mounts the air piston on the pump plunger for limited axial movement of the air piston relative to the pump plunger.

The pump plunger is configured to have a first upper projection on an exterior thereof and a plurality of second lower projections on the exterior thereof. The first projection and the plurality of second projections are on axially opposite sides of the piston. An axial gap between the first projection and the plurality of second projections allows the air piston to move axially between the two projections relative to the pump plunger. The outer diameter of the plunger between the first upper protrusion and the second lower protrusion is slightly smaller than the inner diameter of the air vent of the air piston. This creates a radial gap between the outer surface of the pump plunger and the inner surface of the air vent of the air piston. This radial clearance defines a vent flow path between the pump plunger and the air piston.

The first upper projection is designed as an annular plug. The annular plug engages and seals within the vent bore of the air piston as the pump plunger moves downwardly relative to the air piston. The second plurality of lower projections are spaced around the exterior of the plunger. Each of the plurality of second lower projections is sized to engage within the vent bore of the air piston to inhibit upward movement of the pump plunger relative to the air piston. However, since the plurality of second lower protrusions are arranged at intervals around the pump plunger, they do not block the ventilation flow passage between the pump plunger and the air piston when the second lower protrusions are engaged in the ventilation hole of the air piston.

Thus, when the pump plunger is manually pushed down into the pump housing, the pump plunger first upper projection engages in and closes the vent hole of the air piston. This allows the air piston to compress air in the air pump chamber when the pump plunger pushes the air piston down into the air pump chamber. The limited axial movement of the air piston relative to the pump housing provided by the axially spaced first and second projections causes the first upper projection to move out of the air piston vent hole as the pump plunger is moved upwardly relative to the pump housing by the spring toward its extended position. This opens a vent flow path between the pump plunger and the inner surface of the air piston surrounding the vent hole. Thus, air from the environment external to the dispenser passes through the vent flow passage between the pump plunger and the air piston as the air piston is moved upwardly through the air pump chamber by the pump plunger. This allows the interior volume of the air pump chamber to be vented without the need for an additional valve to control the venting of the air pump chamber.

Because the first and second protrusions on the pump plunger axially move the air piston to a limited extent relative to the pump plunger, the air piston does not begin to pressurize air within the air pump chamber when the pump plunger initially moves downward into the pump housing. To ensure that both air and liquid are simultaneously pumped into the internal discharge passage of the pump plunger, a liquid piston is also mounted on the pump plunger for limited axial movement of the liquid piston relative to the pump plunger. This moves the pump plunger downward into the pump housing a short distance required to seat the first upper projection in the vent hole of the air piston before the pump plunger begins to push the liquid piston downward through the liquid pump chamber. The limited axial movement of the liquid piston relative to the pump plunger causes the air piston and the liquid piston to begin pumping operations from the respective air pump chamber and liquid pump chamber at approximately the same time.

The liquid foaming dispenser of the present invention is thus capable of mixing air and liquid pumped into the discharge passage of the dispenser, thereby producing a dense foam discharged from the dispenser while eliminating the need for a valve to vent air to the air pump chamber as required in prior art dispensers. The elimination of the valve results in a reduction in manufacturing costs. The simplified construction of such a foaming dispenser with a reduced number of component parts also reduces the manufacturing costs of the dispenser. In addition, the air piston is mounted on a pump plunger that is capable of limited axial movement between the air piston and the pump plunger to allow the interior of the air pump chamber to vent quickly as the pump plunger moves upwardly. This ensures that the air pump chamber is vented even if the user of the dispenser causes the pump plunger to reciprocate rapidly within the pump housing without returning it to a fully extended position relative to the pump housing.

Drawings

Further features of the invention are set forth in the following detailed description of preferred embodiments of the invention and the accompanying drawings, in which:

FIG. 1 is a front perspective view of a manually operated foaming liquid dispenser of the present invention attached to the top of a bottle container;

FIG. 2 is a side sectional view of the dispenser taken along line 2-2 of FIG. 1 with the pump plunger in its fully extended position relative to the pump housing and vial container;

FIG. 3 is an enlarged fragmentary view of the relative positions of the air piston and the pump plunger shown in FIG. 2;

FIG. 4 is a side sectional view of the dispenser with the pump plunger in a fully retracted position relative to the pump housing and vial container;

fig. 5 is an enlarged partial view of the relative positions of the air piston and pump plunger shown in fig. 4.

Detailed Description

The foaming liquid dispenser 10 of the present invention is similar to the type of dispenser known in the art as a lotion dispenser. Dispensers of the type described are typically operated by attaching the dispenser to the neck of a bottle container containing the liquid to be dispensed and positioning the dispenser and container upright. In the following description of the liquid foaming dispenser of the present invention, the terms "top" and "bottom", "upper" and "lower" or similar related terms are used to describe the components of the dispenser and their relative positions. These terms are used only because the dispenser is typically positioned upright when dispensing is used. These terms should not be construed as limiting.

The liquid foaming dispenser 10 shown in fig. 1, 2 and 4 consists essentially of a pump housing 12, a pump plunger 14 and a snap ring 16 connecting the pump housing and the pump plunger together. The materials used in constructing the component parts of the dispenser are the same as those commonly used in the industry, typically all of a plastic material except for the metal coil spring used on the pump plunger.

The pump housing 12 basically combines the four cylindrical portions of the pump housing and the connecting cover into one integral piece. The cylindrical portion of the housing and the connecting cap have a common central axis 18 and are axially aligned within the pump housing.

The cylindrical portion includes a cylindrical dip tube connector 22 disposed at the bottom of the pump housing. A cylindrical liquid pump chamber 24, which is the second cylindrical portion of the pump housing, is located directly above the dip tube adapter 22. A valve seat surface 26 is provided at the bottom of the liquid pump chamber 24. The interior volume 28 of the liquid pump chamber 24 communicates with the interior of the dip tube adapter 22 through the valve seat 26. The liquid pump chamber 24 is open at its top end.

The third cylindrical portion of the pump housing 12 is a cylindrical air pump chamber 32 located directly above the liquid pump chamber 24. The air pump chamber 32 has an interior volume 34 that communicates with the interior volume 28 of the liquid pump chamber through the top end opening of the liquid pump chamber 24. The air pump chamber 32 is open at its top end.

The cylindrical sleeve 36 forms a fourth cylindrical portion of the pump housing 12. A sleeve 36 extends upwardly from the top of the air pump chamber 32. Several vial container vent holes 42 extend through sleeve 36. The cylindrical sleeve 36 is also open at the top end.

A cylindrical connecting cap 44 is attached to the bottom of the sleeve 36. As shown in fig. 2 and 4, the attachment cap 44 extends downwardly and is spaced radially outwardly from the air pump chamber 32. The inner surface of the connection cap 44 is provided with a mechanical fitting, such as a bayonet fitting or a screw fitting. The particular fitting employed on the connecting cap 44 cooperates with the fitting on the bottle container employed in the liquid foaming dispenser 10.

As previously described, the dip tube adapter 22, the liquid pump chamber 24, the air pump chamber 32, the cylindrical sleeve 36, and the attachment cap 34 of the pump housing 12 are formed as a single piece. Integrally forming all of these components reduces the total number of individual components of the liquid foaming dispenser 10. This reduction in parts also saves cost in manufacturing the dispenser.

The pump housing 12 is shown mounted on a bottle container 46 in fig. 1, 2 and 4. The bottle container 46 shown in the drawings is only one example of a bottle container that can be used with the liquid foaming dispenser 10. To removably attach the pump housing 12 to the vial container 46, the vial container is provided with a neck 48 having a mechanical fitting that interfits with the mechanical fitting of the pump housing attachment cap 44. After the pump housing 12 is removably attached to the vial container 46 by the attachment cap 44, the liquid pump chamber 24 and the air pump chamber 32 of the pump housing 12 are completely contained within the vial container 46. This reduces the overall size of the liquid foaming dispenser 10 and bottle container 46.

A dip tube 52 is connected to the dip tube adapter 22 at the bottom of the pump housing. The dip tube 52 extends downwardly from the pump housing 12 into the liquid in the container to a position adjacent the bottom of the bottle container 46.

The liquid inlet control valve 54 is located at the bottom of the liquid pump chamber 24. The liquid inlet control valve 54 is a flexible, resilient disc check valve that seats against the valve seating surface 26 at the bottom of the liquid pump chamber 24. The liquid inlet control valve 54 is responsive to the vacuum pressure created within the interior volume 28 of the liquid pump chamber 24. The valve 54 controls the flow of liquid from the bottle container 46 through the dip tube 52 and into the liquid pump chamber interior volume 28 and prevents backflow of the liquid.

A snap ring 16 is fitted to the top of the pump housing 12. The snap ring 16 has a top cap 58 and a cylindrical outer wall 62 that fits tightly around the cylindrical sleeve 36 of the pump housing 12. A cylindrical tube 64 extends upwardly from the snap ring cap 58. A locking tab 65 projects inwardly from the inner surface of the tube 64. The upper portion of tube 64 above snap ring cap 58 provides an aesthetically pleasing cover for the upper portion of pump plunger 14 and a spring mounted pump plunger as will be described further below. A portion of tube 64 extends below snap ring cover 58 to a circular bottom wall 66 of the snap ring.

The snap ring bottom wall 66 has an opening 68 in its center to receive the pump plunger 14, as will be described below. The bottle vent 72 also extends through the snap ring bottom wall 66. A cylindrical plunger tube 74 extends downwardly from the underside of the collar bottom wall 66. Plunger tube 74 limits upward movement of pump plunger 14 relative to pump housing 12 to the extended position of the pump plunger shown in fig. 1 and 2.

A cylindrical vent baffle 76 is fitted over the exterior of the snap ring plunger tube 74 and the interior of the pump housing cylindrical sleeve 36. The vent baffle 76 is configured as a truncated circular ring having a downwardly extending inner cylindrical wall 78, a downwardly extending intermediate cylindrical wall 80, and a downwardly extending outer cylindrical wall 82. An inner cylindrical wall 78 of the vent baffle plate 76 extends downwardly from the inner edge of the baffle plate and is tightly engaged against the outer surface of the snap ring plunger tube 74. The intermediate wall 80 extends over the inner surface of the air pump chamber 32. An outer cylindrical wall 82 extends downwardly from the outer peripheral edge of the vent baffle 76 on the inner surface of the pump housing cylindrical sleeve 36. A gap is provided between the vent baffle outer wall 82 and the pump housing sleeve 36. This gap serves as part of the vent flow path from the environment outside the dispenser and through the pump housing vial vent 42 between the vent baffle outer wall 82 and the sleeve 36.

The pump cylinder 14 is basically comprised of an upper dispenser head 84, a lower piston rod 86, an air piston 88 mounted on the piston rod 86, and a liquid piston 92 mounted on the piston rod 86.

The upper dispenser head 84 has a tubular central cylinder 96 extending downwardly through the dispenser head. The cylinder 96 is open at its bottom. The cylinder bore communicates with a spout 98 of the dispenser head at the top of the cylinder.

A metal coil spring 102 is mounted on the central post 96. The spring engages against the collar bottom wall 66 at its bottom and against the dispenser head 84 at its top. The spring 102 urges the dispenser head and pump plunger 14 upwardly to the extended position shown in figures 1 and 2.

The inner cylindrical wall 104 of the dispenser head 84 extends downwardly over the spring. The inner cylindrical wall 104 has a locking tab 106 projecting outwardly from the wall. Against the bias of the spring 102, the dispenser head 84 is pressed downward and rotated so that the dispenser head locking tab 106 engages the snap ring locking tab 65 below to hold the dispenser head 84 in its downward, retracted position relative to the dispenser 10.

The dispenser head also has an outer cylindrical wall 108. The outer wall 108 telescopes over the collar tube 64. The overlap of the outer wall 108 and the snap ring tube 64 prevents liquid from entering the pump plunger 14 and also provides an aesthetically pleasing appearance to the dispenser.

The internal bore of dispenser head central cylinder 96 and the internal bore of dispenser head spout 98 define a portion of the internal discharge passage of the pump plunger that extends through the length of dispenser head 84. A plug that generates foam is disposed in the interior discharge passage 112 adjacent the bottom of the passage. The plug is comprised of a cylindrical core sleeve 114 having a mesh screen 116 overlying opposite open ends of the core sleeve 114. The air and liquid passing through the two mesh screens 116 of the core sleeve 114 create a foam.

The piston rod 86 of the pump plunger is tubular and has its upper end connected to the lower end of the dispenser head central cylinder 96. The tubular piston rod 86 has an internal bore extending through the length of the rod and communicating with the internal bore of the central cylinder 96 of the dispenser head. The interior bore of piston rod 86, central cylinder 96 of the dispenser head, and spout 98 define a length of an interior discharge passage 112 extending through pump plunger 14. The portion of discharge passage 112 extending through plunger rod 86 and dispenser head central cylinder 96 has a central axis that is coaxial with central axis 18 of pump housing 12.

The piston rod 86 has a cylindrical upper air piston portion 122 and a cylindrical lower liquid piston portion 124. The air piston portion 122 has a cylindrical inner surface extending downwardly through the piston rod to an annular bottom wall 126, which annular bottom wall 126 connects the air piston portion 122 to the liquid piston portion 124 of the piston rod. A pair of diametrically opposed valve openings 128 (only one of which is visible in fig. 5) extend through the annular bottom wall 126. The liquid piston portion 124 of the piston rod also has a cylindrical inner surface extending downwardly from an annular bottom wall 126 to the bottom end of the piston rod 86.

The outer surface of the air piston portion 122 of the piston rod is provided with a first upper projection 132 and a plurality of second lower projections 134. The first protrusion 132 is an annular protrusion that extends completely around the air piston portion 122 of the piston rod. As best shown in fig. 3 and 5, the first protrusion 132 is inclined radially outward while extending axially upward on the outer surface of the piston rod. Each of the plurality of second protrusions 134 is configured as a narrow ridge that protrudes radially outward from the air piston portion 122 of the piston rod while extending axially over the outer surface of the piston rod. The second protrusions 134 are spaced around the air piston portion 122 of the piston rod.

An axial flange 136 is provided on the outer surface of the liquid piston portion 124 of the piston rod. A flange 136 extends downwardly on the outer surface of the liquid piston portion 124 but short of the bottom end of the plunger rod, forming a radial shoulder 138 projecting outwardly from the liquid piston portion 124 of the plunger rod.

An integrated valve assembly comprising a tubular sleeve valve 142, a central rod 144, a spring 146 and a plug check valve 148 is fitted into the interior of the dispenser piston rod 86. The tubular sleeve valve 142 projects upwardly from an annular bottom wall 152 of the valve assembly. The bottom wall 152 has an opening in its center that communicates with the interior of the liquid piston portion 124 of the piston rod and forms part of the interior discharge passage 112 extending through the pump plunger. The outer circumference of the bottom wall 152 engages against the inner surface of the air piston portion 122 of the piston rod and secures the valve assembly in place. A pair of diametrically opposed recesses 154 extend through bottom wall 152 at a location coincident with valve opening 128 of piston rod annular wall 126. The valve assembly elastomeric sleeve 142 is received in the pair of recesses from the bottom wall 152

154 extend upwardly and engage in sealing engagement against the inner surface of the dispenser head center cylinder 96.

The central stem 144 of the valve assembly has a cruciform cross-section. The rod 144 engages against the inner surface of the liquid piston portion 124 of the piston rod to reliably hold the valve assembly in place while allowing liquid to flow axially along the central rod 144. A spring 146 extends downwardly from the bottom end of the rod 144 and biases a plug check valve 148 downwardly.

The valve seat plug 156 is inserted into an opening on the bottom of the liquid piston portion 124 of the piston rod. The valve seat plug 156 has a seating surface 158 against which the plug check valve 148 is engaged. An annular ring 162 on the valve seat plug 156 engages against the bottom of the liquid piston portion 124 of the piston rod to ensure proper positioning of the valve seat plug. The plug check valve 148, which engages against a seating surface 158 of the valve seat plug 156, acts as a liquid outlet valve for the liquid pump chamber 124.

The liquid piston 92 is mounted on the bottom end of the liquid piston portion 124 of the piston rod between the annular ring 162 of the valve seat plug 156 and the radial shoulder 138 of the piston rod axial flange 136. As best shown in FIG. 4, the axial spacing between the valve seat plug annular ring 162 and the shoulder 138 of the axial flange 136 causes the liquid piston 92 to move a small distance axially on the pump cylinder 14. The liquid piston 92 is disposed within the liquid pump chamber 24 in sliding sealing engagement against the interior surface of the liquid pump chamber. The engagement of the liquid piston 92 against the interior surface of the liquid pump chamber 24 moves the liquid piston upwardly relative to the pump cylinder 14 as the piston moves downwardly until the liquid piston 92 engages against the shoulder 138 of the axial flange 136. As the pump plunger moves upward, the liquid piston 92 also moves downward relative to the pump plunger 14 until the liquid piston 92 engages the annular ring 162 of the valve seat plug 156.

The air piston 88 is configured as a flat head ring 164 having an inner cylindrical wall 166 extending downwardly at the inner peripheral edge of the ring and an outer cylindrical wall 168 extending downwardly at the outer peripheral edge of the ring. The inner cylindrical wall 166 of the air piston has an inner surface 172 that is spaced a small distance radially outwardly from the outer surface of the piston rod air piston portion 122 by the inner surface 172. This creates a small annular gap between the outer surface of the piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylindrical wall 166, which acts as a vent flow passage. The radial spacing between the outer surface of the piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylindrical wall 166 defines a vent or vent hole through the air piston 88, wherein the pump plunger 14 extends through the air piston 88. The radial spacing between the outer surface of the piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylindrical wall 166 enables the air piston 88 to move axially to a limited extent relative to the pump cylinder 14. The extent of axial movement of the air piston 88 on the pump plunger 14 is defined by a first upper projection 132 of the pump plunger above the air piston and a second lower projection 134 below the air piston.

The air piston's tack ring 164 extends radially outwardly from the air piston's inner cylindrical wall 166 to the air piston's outer cylindrical wall 168 to position the outer cylindrical wall in a position where it will slidingly and sealingly engage the inner surface of the air pump chamber 32. The sliding sealing engagement of the air piston outer cylindrical wall 168 with the air pump chamber 32 applies sufficient frictional resistance to movement of the air piston 88 relative to the air pump chamber 32 to move the air piston 88 relative to the pump plunger 14 as the pump plunger moves upwardly and downwardly within the pump housing 12.

The first upper projection 132 of the pump plunger piston rod 86 is designed as an annular plug. The outer diameter dimension of the upper projection 132 is slightly larger than the inner diameter dimension of the inner surface 172 of the air piston inner cylindrical wall. As the pump plunger 14 moves downward relative to the air piston 88, the annular plug formed by the upper protrusion 132 engages and seals within the air piston vent hole formed by the inner surface 172 of the inner cylindrical wall. Each of the second plurality of lower projections 134 on the piston rod 86 is sized to engage within the vent bore of the air piston defined by the inner surface 172 of the inner cylindrical wall. The second plurality of lower projections 134 prevent upward movement of the pump cylinder 14 relative to the air piston 88. However, because the plurality of second lower projections 134 are spaced around the pump plunger 14, they do not block the vent flow path between the outer surface of the piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylinder wall 166 when the second lower projections 134 are engaged within the air piston vent defined by the inner cylindrical wall inner surface 172.

Thus, when the pump plunger 14 is manually pushed downwardly into the pump housing 12, the first upper projection 132 of the pump plunger engages and seals within the vent hole of the air piston defined by the inner surface 172 of the air piston inner cylindrical wall 166. This allows the air piston 88 to compress the air within the air pump chamber 32 as the pump plunger 14 pushes the air piston 88 downward into the air pump chamber 32. The limited axial movement of the piston 88 relative to the pump plunger 14 provided by the axially spaced first and second projections 132, 134 causes the first upper projection 132 to move out of the air piston vent defined by the inner surface 172 of the air piston inner cylindrical wall 166 as the pump plunger 14 is moved upwardly by the spring 102 toward its extended position relative to the pump housing 12. This opens a vent flow path between the outer surface of the piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylindrical wall. Thus, as air piston 88 is moved upwardly through air pump chamber 32 by pump plunger 14, the through-flow air from the environment external to dispenser 10 is caused to pass through the nested connection of dispenser head outer cylindrical wall 108 and snap ring tube 64 and flow between the outer surfaces of dispenser head 84 and lower piston rod 86 on the pump plunger and the inner surface of snap ring plunger tube 74 to the vent flow path between the outer surface of piston rod air piston portion 122 and the inner surface 172 of the air piston inner cylindrical wall. This allows the interior volume 34 of the air pump chamber 32 to be vented without requiring an additional valve to control the venting of the air pump chamber.

Because the first and second projections 132, 134 on the pump plunger 14 allow a limited range of movement of the air piston 88 axially relative to the pump plunger, the air piston 88 does not pressurize the air in the air pump chamber 32 when the pump plunger 14 is initially moved downward into the pump housing 12. To ensure that both air and liquid are simultaneously pumped into the interior discharge passage 112 of the pump plunger, the liquid piston 92 is mounted on the piston rod liquid piston portion 124 for limited axial movement of the liquid piston relative to the pump plunger. This moves the pump plunger 14 downwardly into the pump housing 12 a short desired distance before the pump plunger begins to push the liquid piston 92 downwardly through the liquid pump chamber 24 to seat the first upper projection 132 in sealing engagement within the air piston vent opening defined by the inner surface 172 of the air piston inner cylindrical wall. The limited axial movement of the liquid piston 92 relative to the pump plunger 14 causes the air piston 88 and the liquid piston 92 to begin pumping operations from the respective air pump chamber 32 and liquid pump chamber 24 at approximately the same time.

The liquid foaming dispenser of the present invention is thus capable of mixing air and liquid pumped into the discharge passage of the dispenser, thereby producing a dense foam discharged from the dispenser while eliminating the need for a valve to vent air to the air pump chamber as required in prior art dispensers. The elimination of the vent valve results in a reduction in manufacturing costs. This simplified construction of the foaming dispenser also integrates several different component parts of prior art foaming dispensers. In addition, the air piston is fitted over a pump plunger that is capable of limited axial movement between the air piston and the pump plunger to allow the interior of the air pump chamber to vent quickly as the pump plunger moves upwardly. This ensures that the air pump chamber is vented even if the user of the dispenser causes the pump plunger to reciprocate rapidly within the pump housing without returning it to a fully extended position relative to the pump housing.

Although the manually operated foaming liquid dispenser of the present invention has been described above with reference to a single embodiment, it will be understood that variations and modifications may be made to the dispenser without departing from the scope of the invention as claimed, which is defined by the following claims.

Claims (18)

1. A liquid dispenser, comprising:

a pump housing having a liquid pump chamber and an air pump chamber;

a pump plunger within the pump housing, the pump plunger having a central axis defining mutually perpendicular axial and radial directions, and the pump plunger having an internal discharge passage extending axially therethrough;

a liquid piston on said pump plunger disposed within a liquid pump chamber defining an interior volume of said liquid pump chamber, said liquid piston being movable between a fill and a discharge position within said liquid pump chamber in which said liquid piston increases and decreases, respectively, the interior volume of said liquid pump chamber;

an air piston on said pump plunger disposed within an air pump chamber defining an interior volume of said air pump chamber, said air piston being movable between a fill and a discharge position within said air pump chamber in which said air piston increases and decreases, respectively, the interior volume of said air pump chamber, and said air piston being movable relative to said pump plunger between a vent open and a vent closed position of said air piston relative to said pump plunger, wherein in said vent open position of said air piston said air pump chamber vents the exterior environment of said dispenser to vent air into the interior volume of said air pump chamber, and in said vent closed position of said air piston said air pump chamber is sealingly isolated from the exterior environment of said dispenser;

a vent hole through the air piston; and

the pump plunger extends through the vent hole of the air piston, the vent hole of the air piston defining a vent flow path between the plunger and the air piston, the vent flow path venting the interior volume of the air pump chamber to the environment exterior to the dispenser when the air piston is moved to the vent open position relative to the pump plunger.

2. The dispenser of claim 1, further comprising:

the air piston is mounted on the pump plunger for limited axial movement of the air piston relative to the pump plunger between a vent-open position and a vent-closed position of the air piston.

3. The dispenser of claim 1, further comprising:

the pump plunger extends through the vent hole of the air piston, thereby mounting the air piston on the pump plunger for movement of the air piston relative to the pump plunger between vent-on and vent-off positions of the air piston;

a first protrusion on the pump plunger on one side of the air piston;

a second projection on the pump plunger axially spaced from the first projection on a side of the air piston opposite the first projection, the first and second projections defining movement of the air piston relative to the pump plunger within an axial spacing between the first and second projections.

4. The dispenser of claim 3, further comprising:

the vent hole of the air piston defines a vent flow passage between the plunger and the air piston that vents the interior volume of the air pump chamber to the exterior environment of the dispenser when the vent piston moves relative to the pump plunger to the vent open position; and

the first protrusion is disposed on the plunger to engage the air piston and close the air vent and the air vent flow passage of the air piston when the air piston is moved to the air vent closed position relative to the pump plunger.

5. The dispenser of claim 4, further comprising:

the first projection is an annular plug extending around the pump plunger and configured to engage within the vent hole of the air piston to close the vent hole of the air piston when the air piston is in the vent closed position relative to the plunger.

6. The dispenser of claim 4, further comprising:

the second protrusion is disposed on the pump plunger to engage the air piston when the air piston moves to the vent open position relative to the pump plunger to prevent movement of the air piston and maintain the vent flow passage between the pump plunger and the air piston open.

7. The dispenser of claim 4, further comprising:

the second projection is one of a plurality of second projections on the pump plunger spaced around the pump plunger in positions to engage the air piston and maintain the opening of the vent flow passage between the pump plunger and the air piston when the air piston is moved to the vent open position.

8. The dispenser of claim 1, further comprising:

the vent hole is the only hole through the air piston.

9. The dispenser of claim 1, further comprising:

the liquid piston is mounted on the pump plunger for limited axial movement of the liquid piston relative to the pump plunger.

10. The dispenser of claim 9, further comprising:

a liquid pump chamber outlet valve disposed in said pump plunger discharge passage for controlling the flow of liquid from said liquid pump chamber and through said pump plunger discharge passage, said outlet valve being separate from said liquid piston.

11. The dispenser of claim 1, further comprising:

a pump plunger mounted in said pump housing for reciprocal movement relative to said pump housing between extended and retracted positions of said pump plunger;

the liquid piston is movable within the liquid pump chamber between filling and discharge positions in response to movement of the pump plunger between respective extended and retracted positions, wherein the liquid piston increases and decreases an internal volume of the liquid pump chamber when moved to the respective filling and discharge positions;

the air piston is movable within the air pump chamber between a fill and a discharge position in response to movement of the pump plunger between respective extended and retracted positions, wherein the air piston increases and decreases an internal volume of the air pump chamber when moved to the respective fill and discharge positions;

a protrusion disposed on the plunger to open a vent of the air piston in response to movement of the pump plunger to the extended position and to close the vent in response to movement of the pump plunger to the retracted position.

12. The dispenser of claim 11, further comprising:

the air piston is mounted on the pump plunger for axial movement of the air piston relative to the pump plunger between vent open and vent closed positions of the air piston in response to movement of the pump plunger between respective extended and retracted positions, the projection on the pump plunger being displaced from the vent hole of the air piston in the vent open position of the air piston, and the projection on the pump plunger closing the vent hole of the air piston in the vent closed position of the air piston.

13. The dispenser of claim 11, further comprising:

the projection on the plunger is an annular projection extending around the plunger and disposed on the plunger to seat over the vent hole of the air piston to close the vent hole.

14. The dispenser of claim 13, further comprising:

the annular projection is spaced from the air vent of the air piston in response to movement of the pump plunger to the extended position, thereby forming a vent flow path from the interior volume of the air pump chamber to the environment external to the dispenser through the radial spacing between the pump plunger and the air piston.

15. The dispenser of claim 13, further comprising:

the annular protrusion is located on one side of the air piston and a second protrusion is located on an opposite side of the air piston from the annular protrusion, the annular protrusion and the second protrusion enabling limited axial movement of the air piston relative to the pump plunger between the annular protrusion and the second protrusion.

16. The dispenser of claim 15, further comprising:

the second projection is one of a plurality of second projections spaced around the pump plunger in positions to engage the air piston in the vent open position of the air piston and form a vent flow path between the pump plunger and the air piston to vent the interior volume of the air pump chamber to the exterior environment of the dispenser.

17. The dispenser of claim 11, further comprising:

the liquid piston is mounted on the pump plunger for limited axial movement of the liquid piston relative to the pump plunger.

18. The dispenser of claim 11, further comprising:

the vent hole of the air piston is the only hole through the air piston.