FLUID PUMP

Description

TECHNICAL FIELD

Embodiments of the technology relate, in general, to systems, apparatuses and methods for pumping fluids, particularly liquids.

BACKGROUND

Liquid pumps find usefulness in many applications. For example, liquid pumps can be utilized to disperse insecticides, herbicides, fertilizers, and the like from a liquid container. For many applications, a relatively small, relatively quiet, and/or relatively low cost pump can be beneficial.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments will become better understood with regard to the following description, appended claims and accompanying drawings wherein:

FIG. 1 is an isometric view of a pump assembly for pumping fluid;

FIG. 2 is an exploded view of the pump assembly of FIG. 1;

FIG. 3 is a partially transparent isometric view of the pump assembly of FIG. 1 with the inlet connector removed;

FIG. 4 is a partially transparent rotated isometric view of the pump assembly of FIG. 1;

FIG. 5 is a partially transparent rotated isometric view of the pump assembly of FIG. 1 with the motor removed;

FIG. 6 is a front elevation view of the pump assembly of FIG. 1;

FIG. 7 is an isolated back isometric view of an upper cover of the pump assembly of FIG. 1 depicting an inlet chamber and an outlet chamber, in accordance with one embodiment;

FIG. 8 is an isolated back isometric view of a cylinder housing of the pump assembly of FIG. 1, in accordance with one embodiment;

FIG. 9A is a cross sectional view of a portion of the pump assembly taken along the line 9A-9A of FIG. 6;

FIG. 9B is a cross sectional view of a portion the pump assembly taken along the line 9B-9B of FIG. 6;

FIG. 9C is a cross sectional view of a portion of the pump assembly taken along the line 9C-9C of FIG. 6;

FIG. 10 is a side view depicting an interior portion of an exemplary hand-held fluid dispenser including the pump assembly of FIG. 1; and

FIG. 11 is a schematic representation of a system and method for pumping fluid.

DETAILED DESCRIPTION

Certain embodiments are hereinafter described in detail in connection with the views and examples of FIGS. 1-11, wherein like numbers indicate the same or corresponding elements throughout the views.

Various non-limiting embodiments of the present disclosure will now be described to provide an overall understanding of the principles of the structure, function, and use of the apparatuses, systems, methods, and processes disclosed herein. One or more examples of these non-limiting embodiments are illustrated in the accompanying drawings. Those of ordinary skill in the art will understand that systems and methods specifically described herein and illustrated in the accompanying drawings are non-limiting embodiments. The features illustrated or described in connection with one non-limiting embodiment may be combined with the features of other non-limiting embodiments. Such modifications and variations are intended to be included within the scope of the present disclosure.

Reference throughout the specification to “various embodiments,” “some embodiments,” “one embodiment,” “some example embodiments,” “one example embodiment,” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with any embodiment is included in at least one embodiment. Thus, appearances of the phrases “in various embodiments,” “in some embodiments,” “in one embodiment,” “some example embodiments,” “one example embodiment,” or “in an embodiment” in places throughout the specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

The examples discussed herein are examples only and are provided to assist in the explanation of the apparatuses, devices, systems, and methods described herein. None of the features or components shown in the drawings or discussed below should be taken as mandatory for any specific implementation of any of these the apparatuses, devices, systems, or methods unless specifically designated as mandatory. For ease of reading and clarity, certain components, modules, or methods may be described solely in connection with a specific figure. Any failure to specifically describe a combination or sub-combination of components should not be understood as an indication that any combination or sub-combination is not possible. Also, for any methods described, it should be understood that unless otherwise specified or required by context, any explicit or implicit ordering of steps performed in the execution of a method does not imply that those steps must be performed in the order presented but instead may be performed in a different order or in parallel.

Technical solutions to issues related to size, noise, and/or cost of fluid pumps can be achieved by the systems, apparatuses, assemblies, and methods of the present disclosure. In general, the disclosed assemblies and apparatuses can be used to spread, inject, or otherwise distribute fluids supplied to the assembly and apparatus according to the systems and methods of the disclosure. In general, the components of the apparatuses and assemblies described herein, unless otherwise described, can be made of plastic materials, including injection-molded plastic materials. The materials of disclosed pumps and pump components can be selected for chemical resistance, wear resistance, and/or durability, depending on the fluid pump's use application.

FIGS. 1-9C illustrate a pump assembly 100 according to an example embodiment of the present disclosure. The pump assembly 100 can include an upper cover 111, a cylinder housing 123, a gearbox 106, and a motor 102. The upper cover 111 can be sealingly coupled to a first end (e.g., a front end) of the cylinder housing 123 using any number of sealing mechanisms or processes (e.g., glue, fasteners, gaskets, plastic welding, wax, tape, etc.), either individually or in combination. The gearbox 106 can include a gearbox housing 107, which can be coupled or otherwise attached to a second end (e.g., a back end) of the cylinder housing 123 to provide for a moisture-and contaminant-resistant enclosure. As shown in FIGS. 1-2, the gear box housing 107 can include a plurality of attachment tabs 125, each being sized and shaped to cooperate with a corresponding latching connector 124 of the cylinder housing 123. In such arrangements, the gearbox housing 107 can be detachably coupled to the cylinder housing 123. It should be appreciated, however, that in other embodiments, the gearbox housing 107 can be fixedly secured to the cylinder housing 123.

Referring now to FIGS. 1-4, the pump assembly 100 can be powered by a motor, such as, for example, the motor 102. During operation, the motor 102 is configured to rotate a motor output shaft 108 at a reference rotational speed. The motor 102 can be an electric motor energized by a portable power source such as, for example, one or more batteries. As shown in FIG. 4, the motor 102 includes electrical connectors 104, which can be electrically coupled to the portable power source for powering or energizing the motor 102. The motor 102 can be operatively coupled to the pump assembly 100 by the gearbox 106. As shown in FIGS. 3-5, the gearbox 106 can include a plurality of intermeshing gears 109. As described in more detail below, the gears 109 are configured to change, including reduce, a first rotational speed of the motor output shaft 108 of the motor 102 to a second rotational speed of an actuator 130 rotating about a plate 113 of the pump assembly 100.

The plate 113 can be a disk-shaped washer sized and shaped to receive respective gear shafts 115 of the plurality of intermeshing gears 109 of the gearbox 106 on one side and provide a surface about which the actuator 130 can rotate about on the other side. For example, in some embodiments, such as the one shown in FIG. 2, the plate 113 can include a substantially round and flat front surface about which the actuator 130 can rotate. On its rear surface, the plate 113 can include a plurality of cylindrically-shaped bushings extending therefrom, which are configured to receive the gear shafts 115 and aid in maintaining proper positioning of the various gears 109 of the gearbox 106. The plate 113 can be coaxially aligned with a threaded securement 110, which as disclosed in more detail below, can join separate components of the actuator 130, in some embodiments.

As described above, the pump assembly 100 includes an actuator 130. Referring to FIG. 2, the actuator 130 can include a first actuator member 132 and a second actuator member 134. The first actuator member 132 and the second actuator member 134 are generally cylindrical and when joined form the actuator 130 having an annular groove that is a cam path 136 (FIGS. 3-4). As depicted in FIG. 9A, a first portion including a first cam surface 136A of the annular groove is molded into, or machined into, the first actuator member 132 and a complementary second portion including a second cam surface 136B of the annular groove is molded into, or machined into, the second actuator member 134. In some embodiments, such as the one shown in FIGS. 2-4, the first actuator member 132 and the second actuator member 134 are joined together with a threaded securement 110. When the first actuator member 132 is joined to the second actuator member 134, such as by the threaded securement 110, the first cam surface 136A is in a generally parallel, spaced-apart relationship to the second cam surface 136B and define the cam path 136. It should be appreciated that any other attachment or securement mechanisms can be used to join the first actuator member 132 and the second actuator member 134 together. Alternatively, in some embodiments, the actuator 130 can be a single integral or monolithic component having the first cam surface 136A and the second cam surface 136B forming the cam path 136.

As shown in FIGS. 4-5, the bottom portion of the actuator 130, below the cam path 136, is cylindrically-shaped. A plurality of teeth 135 are formed or otherwise extend from the inner surface of the cylindrically-shaped bottom portion of the actuator 130. The teeth 135 are sized and shaped to cooperate with one or more teeth of the intermeshing gear 109 such as, for example, the teeth of gear 109c. In operation, rotation of the motor output shaft 108 by the motor 102 causes the intermeshing gears 109a-c to rotate, which then causes the actuator 130 to rotate about the plate 113.

Referring again to FIGS. 1 and 3, the pump assembly 100 can include an inlet port 152 and an outlet port 156. In an embodiment, the inlet port 152 and/or an outlet port 156 can be joined to, or molded into, the upper cover 111, which can be joined to the cylinder housing 123. The pump assembly 100 may, in an embodiment, include an inlet connector 153 (shown best in FIGS. 4 and 9). The inlet connector 153 may be coupled to the cover 111 and include an inlet port 157 fluidically coupled with the inlet port 152.

The cylinders, actuator, and other working components of the pump assembly 100, as described below, can be housed in a cylinder housing 123. The pump assembly 100 can include a plurality of pistons. In an embodiment, the pump assembly 100 includes a first piston 112 and a second piston 114. The first piston 112 and the second piston 114 each reciprocate in a linearly parallel configuration inside a first cylinder 116 and a second cylinder 118, respectively. The first cylinder 116 and the second cylinder 118 can each be a cylindrical-shaped bore inside the cylinder housing 123, shown in more detail in FIGS. 8 and 9A. The cylinder housing 123 can be joined to the gearbox housing 107 and can cooperate to house the gearbox 106 and the actuator 130 (described more fully below). The first piston 112 is generally cylindrical, having a central axis 142 being coaxial with a central axis 144 of the first cylinder 116. Likewise, the second piston 114 is generally cylindrical, having a central axis 146 being coaxial with a central axis 148 of the second cylinder 118. In an embodiment, the first piston central axis 142, the second piston central axis 146 are parallel. In an embodiment, the first piston central axis 142, the second piston central axis 146, and the central axis 150 of the actuator 130 are each parallel and coplanar. A first piston seal 120 can be sized to provide for a substantially leak-free seal between an outer surface of the first piston 112 and the inner wall of the first cylinder 116. Likewise, a second piston seal 122 can be sized to provide for a substantially leak-free seal between an outer surface of the second piston 114 and the inner wall of the second cylinder 118. In an embodiment, the first piston seal 120 and the second piston seal 122 can be an O-ring disposed at or near a distal end of the first cylinder 116 and the second cylinder 118, respectively. Thus, each cylinder 116, 118 is a variable-volume fluid reservoir, with the volume being cyclically alternating from a first minimum volume to a second maximum volume as a function of the reciprocating motion of the corresponding piston.

As shown in FIG. 2, in an embodiment, a piston holder 119 can facilitate retention of the first and second pistons 112, 114 within the cylinder housing 123 (i.e., within the first and second piston cylinders 116, 118, respectively). The piston holder 119 can define a slot 151 (one shown) on each of opposing sides in which a connecting rod pin (e.g., 138, 140) on each respective piston (e.g., 112, 114) (and which can be oriented opposite the respective cam followers 138, 140) can travel with the reciprocating piston. The connecting rod pin (e.g., 138, 140) in the slot 151 can prevent the pistons 112 114 from rotating and becoming disconnected from the rotating actuator 130 that provides the reciprocating movement of the pistons 112, 114.

Each of the first piston 112 and the second piston 114 can be actuated in reciprocating motion within the first and second piston cylinders 116, 118 by the rotation of the actuator 130. The actuator 130 rotates via an actuator shaft that is driven by the motor 102 via the gearbox 106. The actuator 130 can comprise a first actuator member 132 and a second actuator member 134 (FIG. 2). The first actuator member 132 and the second actuator member 134 can be generally cylindrical and can be coupled together to form the actuator 130. The first actuator member 132 and the second actuator member 134 can cooperate to define a cam path 136 (FIGS. 3-4) that is formed as an annular groove. As depicted in FIG. 9A, a first portion including a first cam surface 136A of the cam path 136 is molded into, or machined into, the first actuator member 132 and a complementary second portion including a second cam surface 136B of the cam path 136 is molded into, or machined into, the second actuator member 134. When the first actuator member 132 is joined to the second actuator member 134, such as by the threaded securement 110, the first cam surface 136A is in a generally parallel, spaced-apart relationship to the second cam surface 136B and define the cam path 136.

The first piston 112 has at or near its proximal end a first cam follower 138 that extends into the cam path 136. Likewise, the second piston 114 has at or near its proximal end a second cam follower 140 that extends into the cam path 136. Thus, each piston 112, 114 is coupled by their respective cam followers 138, 140 to the actuator 130 in such a way that rotation of the actuator 130 causes each of the first and second pistons 112, 114 to slide (e.g., translate) either downwardly (e.g., an intake stroke) or upwardly (e.g., an exhaust stroke). For each of the first and second cylinders 116, 118, fluid can be drawn into the respective cylinders (116, 118), during the intake stroke and exhausted from the respective cylinders (116, 118) during the exhaust stroke. The stroke direction of the first piston 112 can be opposite the stroke direction of the second piston 114 such that when the first piston 112 is in its intake stroke (e.g., sliding downwardly), the second piston 114 can be in its exhaust stroke (e.g., sliding upwardly) and vice versa. Each of the first and second pistons 112, 114 can have a top dead center position that corresponds to a position of maximum advance and a bottom dead center position that corresponds to a position of maximum retraction. The advance position of the first piston 112 can be opposite the advance position of the second piston 114 such that when the first piston 112 is at top dead center, the second piston 114 is at bottom dead center and vice versa.

As best depicted in FIGS. 7, 9A, and 9B, in one embodiment, the first and second cylinders 116, 118 can be in fluid communication at their respective distal ends with an inlet chamber 158 and an outlet chamber 159. As will be described in further detail below, when the first piston 112 travels through its intake stroke, fluid can be drawn from the inlet port 152, through the inlet chamber 158 and into the first cylinder 116. When the first piston 112 travels through its exhaust stroke, fluid can be expelled from the first cylinder 116, through the outlet chamber 159 and discharged from the outlet port 156. The second piston 114 can operate in a similar manner.

Referring now to FIG. 9A, a first inlet check valve 160 can be associated with the first cylinder 116 and can be selectively operable in either a closed state or an opened state. When in the closed state, the distal perimeter portion of the circularly extending flap of the first inlet check valve 160 can be sealed over openings 163 (see FIG. 8) that extend to the inlet chamber 158 to substantially seal and prevent fluid flow from the first cylinder 116 into the inlet chamber 158. When in the opened state, the distal perimeter portion of the circularly extending flexible flap of the first inlet check valve 160 can be outwardly biased, thereby permitting fluid flow from the inlet chamber 158, through the openings 163 (FIG. 8) and into the first cylinder 116.

A second inlet check valve 164 can be associated with the second cylinder 118 and can be selectively operable in either an open state or a closed state. When in the closed state, the distal perimeter portion of the circularly extending flap of the second inlet check valve 164 can be sealed over openings 165 (see FIG. 8) that extend to the inlet chamber 158 to substantially seal and prevent fluid flow from the second cylinder 118 into the inlet chamber 158. When in the opened state, the distal perimeter portion of the circularly extending flexible flap of the second inlet check valve 164 can be outwardly biased, thereby permitting fluid flow from the inlet chamber 158, through the openings 165 (FIG. 8) and into the second cylinder 118. In one embodiment, the first and second inlet check valves 160, 164 can each comprise an umbrella valve having a generally circularly extending flexible flap that can move from a closed position and an open position. It is to be appreciated that any of a variety of suitable alternative inlet check valve configurations are contemplated.

Still referring to FIG. 9A, the first and second cylinders 116, 118 have at their respective distal ends a first outlet opening 172 (also shown in FIG. 8) and a second outlet opening 176, respectively. The first and second outlet openings 172, 176 can be in fluid communication with the outlet chamber 159 (FIG. 7), which is in turn in fluid communication with the outlet port 156. A first outlet check valve 174 can be associated with the first cylinder 116 and can be selectively operable between an opened position and a closed position. When in the closed position, the first outlet check valve 174 can be in contact with a valve seat 197 (FIG. 9B) to provide a seal therebetween that prevents fluid flow from the first cylinder 116 into the outlet chamber 159. When in the opened position, the first outlet check valve 174 can be spaced from the valve seat 197 (and can rest against a valve stop 194) to allow fluid flow from the first cylinder 116 into the outlet chamber 159. The first outlet check valve 174 can be biased into the closed position by a spring 184

A second outlet check valve 178 can be associated with the second cylinder 118 and can be selectively operable between an opened position and a closed position. When in the closed position, the second outlet check valve 178 can be in contact with a valve seat 199 to provide a seal therebetween that prevents fluid flow from the second cylinder 118 into the outlet chamber 159. When in the opened position, the second outlet check valve 178 can be spaced from the valve seat 199 (and can rest against a valve stop 196) to allow fluid flow from the second cylinder 118 into the outlet chamber 159. The second outlet check valve 178 can be biased into the closed position by a spring 186.

In one embodiment, the first and second outlet check valves 174, 178 can comprise a plunger valve. In other embodiments, the first and second outlet check valves 174, 178 can be any other type of plug or valve having any of a variety of sizes and shapes that facilitate sealing contact with valve seats (e.g., 197,199). It is to be appreciated that any of a variety of suitable alternative check valves are contemplated.

In one embodiment, the first piston 112 and the second piston 114 do not permit fluid to pass out of their respective cylinders 116, 118 except through one of the outlet check valves 174, 178. The outlet check valves 174, 178 may be generally disposed toward the upper cover 111, near the inlet port 152 and outlet port 156, both of which are disposed on one end (e.g., the distal end) of the cylinders 116, 118. That is, in one embodiment, the pistons 112, 114 are solid, such that fluid does not pass through the pistons 112, 114, but is drawn into the cylinders 116, 118 and displaced out of the cylinders 116, 118 without being in contact with any other pump components other than the inlet port 152 and the outlet port 156, both of which include fluid paths (e.g., through the inlet and outlet chambers 158, 159) generally leading to or from the top of the cylinders, that is, the distal end of the cylinders 116, 118 nearest the upper cover 111.

The first and second inlet check valves 160, 164 and the first and second outlet check valves 174, 178 can cooperate with the first and second pistons 112, 114 to facilitate pumping of fluid from the inlet port 152 to the outlet port 156. For example, when the first piston 112 travels along its exhaust stroke (e.g., from a bottom dead center position in the direction of arrow 177 to the top dead center position shown in FIG. 9A), the pressure generated in the first cylinder 116 can urge the first inlet check valve 160 into the closed state while simultaneously urging the first outlet check valve 174 into the opened position (in the direction of arrow 180). The fluid disposed in the first cylinder 116 during the exhaust stroke can accordingly be urged through the first outlet opening 172, around the first outlet check valve 174 (along the path 188), to the outlet chamber 159 and out of the outlet port 156. The second piston 114 can travel along its intake stroke (e.g., from a top dead center position in the direction of arrow 179 to the bottom dead center position shown in FIG. 9A) simultaneously with the first piston 112. The resulting pressure generated in the second cylinder 118 can urge the second inlet check valve 164 into the opened state while simultaneously urging the second outlet check valve 178 into the closed position (in the direction of arrow 182). The fluid at the inlet port 152 can accordingly be drawn into the inlet chamber 158, through the opening 165 (in the direction of arrow 190 in FIG. 8), around the second inlet check valve 164 (along the path 170), and into the second cylinder 118 to effectively fill the second cylinder 118 with fluid.

Once the first and second pistons 112, 114 reach the top dead center and bottom dead center positions, respectively, shown in FIG. 9A, they can then reverse direction towards an intake stroke (in the direction of arrow 181) and an exhaust stroke (in the direction of arrow 183), respectively. When the first piston 112 travels along its intake stroke (e.g., from the top dead center position shown in FIG. 9A to the bottom dead center position), the pressure generated in the first cylinder 116 can urge the first inlet check valve 160 into the open state while simultaneously urging the first outlet check valve 174 into the closed position (opposite the direction of arrow 180). The fluid at the inlet port 152 can accordingly be drawn into the inlet chamber 158, through the opening 163 (in the direction of arrow 191 in FIG. 8), around the first inlet check valve 160, and into the first cylinder 116 to effectively fill the first cylinder 116 with fluid.

The second piston 114 can travel along its exhaust stroke (e.g., from the bottom dead center position as shown in FIG. 9A to the top dead center position) simultaneously with the first piston 112. The resulting pressure generated in the second cylinder 118 can urge the second inlet check valve 164 into the closed state while simultaneously urging the second outlet check valve 178 into the opened position (opposite the direction of arrow 182). The fluid disposed in the second cylinder 118 during the exhaust stroke can accordingly be urged through the second outlet opening 176, around the second outlet check valve 178, to the outlet chamber 159 and out of the outlet port 156. The first and second pistons 112, 114 can continue to operate in this manner to facilitate pumping of fluid from the inlet port 152 to the outlet port 156.

Referring now to FIGS. 2 and 9C, in one example embodiment, the pump assembly 100 includes a pressure control member 202 that can limit the pressure of fluid exiting the pump assembly 100 to a predetermined pressure. Fluid can enter the inlet port 157 of the inlet connector 153 in the direction of arrow 204, and exit the outlet port 156 in the direction of arrow 206. The fluid path follows that described above, i.e., into the cylinders 116, 118 from the inlet chamber 158, and out of the cylinders 116, 118 to the outlet port 156. In an embodiment, an output tube 458 (FIG. 11) having a nozzle (not shown) can be attached to the outlet port 156 to provide a fluid path from the outlet port 156 to the nozzle. The nozzle may have a structure that restricts fluid flow, which creates back pressure. The volume of fluid, and in turn, the back pressure may be reduced or controlled to a predetermined value. The pressure control member 202 can facilitate control of the back pressure to a maximum, or otherwise predetermined, value by serving as an overpressure relief check valve that permits fluid at a predetermined pressure to flow through a pressure relief channel 260 from the outlet port 156 back to the inlet port 152, in the direction indicated by the arrow 212.

Still referring to FIG. 9C, in one embodiment, the pressure control member 202 can include a spring biased plunger 155 that sealingly seats against a valve seat 161 in the pressure control member 202 to prevent fluid flow from the outlet port 156 to the inlet port 152. The plunger 155 is biased against the valve seat 161 by a spring 154, which can be a coil spring that presses with a predetermined force on the plunger 155. In some embodiments, such as the one shown in FIG. 2, the pressure control member 202 can include the inlet connector 153, which is configured to provide an opposing force against a portion of the spring 154 distal to the portion of the spring 154 that contacts the plunger 155. The plunger 155 can prevent fluid from flowing from the outlet port 156 to the inlet port 152 unless and until the pressure of the fluid in the outlet port 156 is sufficient to cause the spring 154 to compress, and, therefore, the plunger 155 to be separated from the valve seat 161, thus permitting fluid flow from the outlet port 156 to the inlet port 152 in the direction of arrow 212, thereby reducing the back pressure at the nozzle. Once the back pressure at the nozzle is reduced to the predetermined maximum pressure or below, the spring force of the spring 154 urges the plunger 155 against the valve seat 161, and remains sealingly seated until the back pressure once again causes unseating, and fluid flow in the direction of arrow 212. The pressure control member 202 can continuously cycle from a closed valve condition to an open valve condition to keep the back pressure at the nozzle relatively constant during use of the pump assembly 100. It is to be appreciated that the plunger 155 can be any other type of plug or valve having any of a variety of sizes and shapes that facilitate sealing contact with a valve seat (e.g., 161).

In a method of operation, fluid from a supply reservoir, such as a bottle, tank, or the like, can be dispersed in a controlled manner utilizing the pump assembly 100 described herein, for example, through a hand-held wand joined to the outlet port. In an embodiment, a supply reservoir can be connected in fluid communication to the inlet port 152, such as by a flexible tube. As the actuator 130 rotates, for example, by being driven by the motor 102 in rotational motion, the cam path 136 rotates to force the pistons, coupled by their respective cam followers, into a reciprocal linear motion, with each piston being 180 degrees out of phase with the other. As a piston retracts, such as depicted in FIGS. 9A and 9B with second piston 114, a partial pressure is created in the cylinder. The partial pressure acts to cause the inlet check valve to open, thereby drawing fluid from the supply reservoir, through the inlet port, and into the cylinder. As a piston advances, such as depicted in FIGS. 9A and 9B with first piston 112, the pressure induced on the fluid in the cylinder both closes the inlet check valve and forces open the outlet check valve to permit the fluid in the cylinder to be forced out to the outlet port. In an embodiment, a handheld wand in fluid communication with the outlet port can be manipulated to direct dispersed fluid from a wand nozzle, for example.

With reference to FIG. 10, the pump assembly 100 can be part of a hand-held fluid dispenser 300, in one embodiment. The hand-held fluid dispenser 300 can be of the type known to be used with commercially available herbicides. As shown in FIG. 10, the pump assembly 100 and the motor 102 can be mounted into a handle body 302, which can be a molded plastic handle. The handle body 302 can include a power supply for the motor 102, such as, for example, one or more batteries 304. A depressible trigger member 306 can be spring-biased by a spring 308 into an extended position, in which an electrical circuit connecting power from the batteries 304 via electrical conductors 310 to the electrical connections 104 is open. When the trigger member 306 is urged against the spring force of the spring 308 a sufficient distance, the electrical circuit is closed, permitting power from the batteries 304 to energize the motor 102, which in turn causes rotational motion of the actuator 130. Rotational motion of the actuator 130 causes the reciprocating motion of the pistons and the resulting fluid movement from the inlet port to the outlet port, as described herein.

In a method of operation, as depicted schematically in FIG. 11, the hand-held fluid dispenser 300 can be used to pump fluid 450 from a supply reservoir 452, such as a bottle, tank, or the like. The fluid 450 can be drawn in the direction of arrow 400 into a supply tube 456, which can be a flexible tube. The supply tube 456 extends into the supply reservoir 452 to a connection at the inlet port 152, as described above. In an embodiment, the supply tube 456 is coupled to the inlet connector 153. The fluid 450 can be dispersed in a controlled manner utilizing the pump assembly 100 through the output tube 458 joined to the outlet port 156. Fluid can be dispensed from a distal end of the output tube 458 in the direction of arrow 460. In operation, the actuator 130 rotates, for example, by being driven by the motor 102 in rotational motion, thus rotating the cam path 136 to force the pistons, coupled by their respective cam followers, into a reciprocal linear motion, with each piston being 180 degrees out of phase with the other. As a piston retracts, such as depicted in FIGS. 9A and 9B with second piston 114, a partial pressure is created in the cylinder. The partial pressure acts to cause the inlet check valve to open, thereby drawing fluid from the supply reservoir 452, through the supply tube 456 and to the inlet port 152, and into one of the cylinders 116, 118. As a piston advances, such as depicted in FIGS. 9A and 9B with first piston 112, the pressure induced on the fluid in the cylinder both closes the inlet check valve and forces open the outlet check valve to permit the fluid in the cylinder to be forced out to the outlet port. In an embodiment, the output tube 458 coupled in fluid communication with the outlet port 156 can be a handheld wand that can be manipulated to direct dispersed fluid from a wand nozzle, for example.

The foregoing description of embodiments and examples has been presented for purposes of illustration and description. It is not intended to be exhaustive or limiting to the forms described. Numerous modifications are possible in light of the above teachings. Some of those modifications have been discussed, and others will be understood by those skilled in the art. The embodiments were chosen and described in order to best illustrate principles of various embodiments as are suited to particular uses contemplated. The scope is, of course, not limited to the examples set forth herein, but can be employed in any number of applications and equivalent devices by those of ordinary skill in the art. Rather it is hereby intended the scope of the invention to be defined by the claims appended hereto.