Cross-Reference to Related Application

[0001] The present application relates and claims priority to United States Provisional Application No. 63/054885, filed July 22, 2020, the entire contents of which are hereby incorporated by reference.

Field of the Invention

[0002] The present disclosure is directed generally to a wave cam drive system for a liquid pump sprayer that provides enhanced pumping performance and a low weight and size for a comparable liquid pump.

Background

[0003] Many hand-held lawn and garden sprayers utilize a battery-powered and electric- motor driven liquid pump to provide the pressure needed to spray liquids. Employing light weight and compact spray bottle or spray wand applicators, these sprayers provide the user with a more effortless spray session as compared to comparable manual-pump sprayers.

[0004] Figure 1 shows a typical battery-powered, hand-held spray bottle type applicator. Because the entire sprayer is held in one hand, the weight and compactness of the battery, motor, and pump is an important consideration, as shown in Figure 2.

[0005] Figure 3 shows a typical battery-powered, hand-held spray wand type applicator. [0006] As compared to the bottle sprayer, the weight (and corresponding volume) of the liquid is greater in the separately-held bottle. Figure 4 illustrates the liquid pump, electric motor, and battery contained within the spray wand. The need for a lightweight and compact pump system remains important for ease of use and spray application performance.

[0007] Figure 4 illustrates this use of the spray wand type liquid sprayer to apply herbicide. IT should be noted that the weight of the spray system is distributed, with the liquid-filled bottle carried in one hand, and the spray wand, consisting of the battery, motor and pump, held in the other.

[0008] For both the spray-bottle and spray -wand type electric liquid pump lawn and garden sprayers, the need exists for a pump system that minimizes the hand-held weight and size of the applicator, while maintaining or exceeding the pumping performance relative to a comparative liquid pump applicator. [0009] Accordingly, there is a need in the art for an electric motor powered liquid pump lawn and garden sprayer that (1) reduces weight and size of the overall pump, while

(2)exceeding performance characteristics of a comparable liquid pump spray applicator , and

(3) improving user comfort and ease-of-use, resulting in greater overall sprayer operating efficiency.

Summary

[0010] The present disclosure is directed to a wave cam drive system for a liquid pump sprayer that provides for improved pumping performance and a reduction in weight and size for a comparable liquid pump.

[0011] According to an aspect is a drive system for a liquid pump used to provide the pressure needed to spray liquids, comprising a housing; a motor having a drive shaft extending along a first longitudinal axis; a cam operably coupled to the drive shaft and comprising a cam surface formed in an undulating pattern that is non-planar and undulates in a predetermined number of cycles with each cycle representing a stroke distance, whereby the cam rotates about the first longitudinal axis when power is provided to the motor; an inlet port and an outlet port extending from and in fluid communication with the interior of the housing; a plurality of pistons mounted within the housing for reciprocating inlet stroke and outlet stroke movement along respective longitudinal axes each of which is parallel to the first longitudinal axis; a plurality of follower springs each one of which is operably associated with a respective one of the plurality of pistons and provide the bias force to reciprocally move each piston; and a plurality of followers positioned in contacting and sandwiched relation between the cam surface and a respective one of the plurality of pistons.

[0012] According to an embodiment, the plurality of pistons comprise three pistons arranged in a circular pattern with each piston positioned 120 degrees relative to the others. [0013] According to an embodiment, the followers are formed as spherical balls each of which is adapted to rotate on the cam surface as the cam rotates about the first longitudinal axis.

[0014] According to an embodiment, wherein each of the plurality of pistons includes a follower receiver positioned on its bottom surface, wherein each follower engages a respective follower receiver.

[0015] According to an embodiment, wherein the undulating pattern on the cam surface creates a series of two inlet stroke and two outlet stroke reciprocating movements in each piston for every full rotation of the cam. [0016] These and other aspects of the invention will be apparent from the embodiments described below.

Brief Description of the Drawings

[0017] The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which: [0018] FIG. 1 is a perspective view of a prior art battery-powered hand-held type spray bottle.

[0019] FIG. 2 is a perspective, enlarged view of the prior art sprayer portion of the spray bottle of FIG. 1 with internal features shown.

[0020] FIG. 3A is a perspective view of a prior art battery-powered spray wand type applicator.

[0021] FIG. 3B is a perspective, enlarged view of the prior art spray wand portion of the spray wand applicator of FIG. 3 with internal features shown.

[0022] FIG. 3C is a perspective view of the prior art spray wand applicator in use.

[0023] FIG. 4 is an exploded perspective view of showing a wave cam drive system, in accordance with an embodiment, applied to the prior art spray wand applicator of FIG. 3 A. [0024] FIG. 5A is a top plan view of a wave cam drive system, in accordance with an embodiment.

[0025] FIG. 5B is a front elevation view of a wave cam drive system, in accordance with an embodiment.

[0026] FIG. 5C is a cross-sectional view a wave cam drive system taken along section line 5C-5C of FIG. 5 A, in accordance with an embodiment.

[0027] FIG. 6 is a perspective view illustrating the circular arrangement of piston and inlet valves of a wave cam drive system, in accordance with an embodiment.

[0028] FIG. 7 is a cross-sectional view illustrating in two halves the basic function of the inlet and outlet valves of a wave cam drive system, in accordance with an embodiment.

[0029] FIG. 8A is a perspective view illustrating the wave cam drive system, in accordance with an embodiment.

[0030] FIG. 8B is an exploded perspective view illustrating the wave cam drive system, in accordance with an embodiment.

[0031] FIG. 9A is a top plan annotated view of a wave cam, in accordance with an embodiment.

[0032] FIG. 9B is a front elevation view of a wave cam, in accordance with an embodiment. [0033] FIG. 9C is a bottom perspective view of a wave cam, in accordance with an embodiment.

[0034] FIG. 9D is a top perspective view of a wave cam, in accordance with an embodiment. [0035] FIG. 10A is a cross-sectional view taken along section line 10A-10A of FIG. 9A illustrating the surface profile that positions the follower of one piston at maximum lift with the cam at 0 degrees and 180 degrees clockwise rotation, in accordance with an embodiment. [0036] FIG. 10B is a cross-sectional view taken along section line 10B-10B of FIG. 9A illustrating the surface profile that positions the follower of one piston at minimum lift with the cam at 90 degrees and 270 degrees clockwise rotation, in accordance with an embodiment. [0037] FIG. 11 is a portion of the cross-sectional view of FIG 5C illustrating the relative full displacement (stroke) of the pistons between positions of maximum and minimum lift, in accordance with an embodiment.

[0038] FIG’S 12A - 12C are top plan, front elevation, and perspective views, respectively, of a wave cam, in accordance with an embodiment.

Detailed Description of Embodiments

[0039] The present disclosure describes a wave cam drive system 10 for a liquid pump sprayer 100.

[0040] Referring to FIG. 4, in one embodiment, identifies the wave cam drive system 10 as applied to a spray wand type applicator 100 having a liquid container 102 and a spray wand 104 in which an electric motor 106 and power source (e.g., batteries) 108 are contained.

[0041] Referring to FIG’S 5A-5C, the components of the wave cam drive systemlO are shown, with FIG. 5C showing them in section through the pump-motor assembly. In this embodiment, the wave cam drive 10 is applied to a piston pump. The fundamental elements of the wave cam drive 10 are the wave cam 12 and the follower 14. The wave cam 12 is operably coupled to the drive shaft of motor 106 such that it is driven about axis X-X when power is applied to the motor. The additional components of wave cam drive system 10 include pistons 16, 18 and 20; piston seals 22 that seal each piston at an upper and lower position within the stroke cylinder; return springs 24 that provide the bias to each piston permitting them to reciprocate along their stroke paths; and an inlet and an outlet port 26, 28, respectively, that are in fluid communication with the pistons. Outlet port 28 is positioned co-axial with axis X-X. Pistons 16, 18 and 20 each extend along longitudinal axes A- A, B-B, and C-C, respectively, that are parallel to axis X-X. A housing 30 provides the cavity in which the elements are contained with the inlet and outlet ports extending outside the housing. [0042] FIG. 6 illustrates the compact circular arrangement of pistons 16, 18 and 20 that are possible with the wave cam drive system 10. Any appropriate number of pistons may be driven by this system. The three piston 16, 18, 20 employ this circular arrangement, resulting in a compact and light weight pump with improved liquid displacement within the available space. [0043] FIG. 7 demonstrates the basic function of the inlet and outlet valves 32, 34, respectively. As shown in FIG. 6, the inlet valves 32 follow the circular arrangement of the piston componentry, while the outlet valve 34 is centrally positioned, with flexible feature sealing elements aligned with their respective ports.

[0044] For a piston driven on its outlet stroke (at left in FIG. 7), the flexible respective element of the centrally positioned outlet valve 34 opens under liquid pressure, while the inlet valve 32 is simultaneously closed by the liquid pressure. A piston returning on its inlet stroke (at right in FIG. 7) causes the flexible inlet valve 32 to open due to the negative liquid pressure, while the flexible outlet valve element 34 is simultaneously closed by the same negative pressure.

[0045] Via the followers 14 and with the return springs 24, the piston displacements are uniquely controlled by the wave cam 12. The wave cam 12 is a circular disk in form that, as shown, is coupled on its axis to and driven by the electric motor output shaft. Alternatively, the wave cam 12 may be indirectly coupled to the electric motor output shaft by a gear pair or gear train (not shown), in order to rotate the wave disk at a higher or lower angular velocity than that of the motor shaft.

[0046] FIGS 8A and 8B provide perspective internal views of the wave cam pump drive system, continuing with the three-piston pump arrangement. Note that, alternatively, this drive system could similarly operate a diaphragm pump with one or more diaphragm follower components.

[0047] The top face of the rotating wave cam 12 has a surface profile with an undulating pattern that controls the linear movement of the followers 14. In one embodiment, the followers 14 are of rolling ball form that couple to and are located by a receiving feature 36 positioned at the base of the piston. Alternatively, the followers 14 could take a different form; for example, cylindrical roller elements could be utilized. Note that the axis of rotation of the wave cam 12 is parallel with the lines of action of the followers 14 and pistons 16, 18 and 20. [0048] FIG. 9 discloses the form of wave cam 12 as employed in this three-piston pump example. In this embodiment and for explanation, the relative motion of one follower/piston (Piston 1) is described during one rotation of the wave cam 12. The piston will rise and fall to maximum and minimum lift positions as the wave cam rotates. [0049] Corresponding to the initial cam angular position at 0°, the piston is initially positioned at maximum lift profile on the cam surface. With the wave cam now rotating clockwise (CW) relative to the piston, the piston falls to its minimum lift position at 90° cam rotation. Continuing now with relative CW cam rotation, the piston is lifted over the next 90°, returning to maximum lift at 180° cam rotation. With continued rotation, the piston will again fall to minimum lift at 270°, and then return to maximum lift as the wave cam returns to its 0° initial angular cam position, after one full revolution.

[0050] FIGS 10A and 10B describe the surface profile of the wave cam 12 in more detail, with section views 10A-10A and 10B-10B as taken from FIG. 9A.

[0051] Section 10A-10A shows the surface profile that positions the follower of piston number one at maximum lift (top dead center, or TDC) with the wave cam at 0° and 180° CW rotation.

[0052] Section 1 OB-10B shows the surface profile that positions the follower of piston number one at minimum lift (bottom dead center, or BDC) with the wave cam at 90° and 270° CW rotation.

[0053] FIG. 11 now indicates, with reference to the assembly view of FIG. 5C, the relative full displacement (stroke) of the piston between its positions of maximum and minimum lift. [0054] A performance benefit of this wave cam drive system is that for each revolution of the cam, each piston will achieve four complete strokes. As outlined in Figure 9, within one revolution of the wave cam, the piston falls to establish the 1st inlet stroke, then rises to produce the 1st outlet stroke, then falls again to establish the 2nd inlet stroke and, finally, rises to produce the 2nd outlet stroke.

[0055] Conventional eccentric-drive or crank-drive piston pumps will produce only two strokes per piston per revolution of the eccentric or crank.

[0056] For the three piston example, the wave cam drive system 10 will produce 12 strokes per revolution of the wave cam 12.

[0057] As initially referenced in FIG’S. 8 A and 8B, the rotating and undulating wave cam surface profile is designed to control the follower motion. FIGS 12A-12C identify the diametrical size of the wave cam 12 in front and top views, and the undulating surface profile of the wave cam in a perspective view.

[0058] The surface profile of the wave cam may be designed to move the follower such that the follower may dwell, or remain at rest, for a period of cam rotation, between rising and falling motion. Additionally, the surface profile of the wave cam may be designed to impart standard follower motion schemes, such as constant velocity, constant acceleration, and harmonic motion.

[0059] The overall diameter of the wave cam may be of any appropriate size, as needed to engage the applicable number of piston followers (or diaphragm followers, in the case of a diaphragm pump) or other functional pump design size considerations.

[0060] Of continued importance, a combination of diametrical and surface profile characteristics of the wave cam would permit different pump followers at to operate along separate and distinct paths or tracks. For example, one follower could produce a single defined stroke and motion scheme in one cam revolution, whereas a second follower, operating at a different diameter and along a unique profile, could produce two defined strokes in the same cam revolution. With this arrangement, the flow and pressure characteristics of the pump can be adjusted in novel ways.

[0061] The stroke, or maximum rise-and-fall displacement of the follower, as referenced in Figures 10 and 11, are designed to meet the desired flow characteristics of the applicable pump. Along with the previously described profile characteristics for follower rise, fall, and dwell, the stroke may be of any design value appropriate to the desired sprayer performance characteristics.

[0062] Importantly, in addition to designing the surface profile of the wave cam to achieve a desired follower stroke, the wave cam itself may be user-adjustable to different height location settings relative to its initial set position along its axis of rotation. In combination with an appropriate follower arrangement, this setting adjustability would permit the user to beneficially adjust the pump stroke to any number of appropriate settings during a spraying session, which would permit such pump performance characteristics as pressure and flow to meet the needs of the session.

[0063] With reference to the threaded housing components shown in FIG. 5C, it is noted that ease of assembly of the liquid pump is provided with this configuration.

[0064] The wave cam drive system 10 described herein provides for a compact arrangement of piston pump (or diaphragm pump) componentry as compared to traditional piston and diaphragm pump designs. This compact arrangement, as a result, permits a larger pump displacement to be employed for higher performance outcomes within a given competitive size for the spray bottle or spray wand applicator.

[0065] Alternatively, and equally beneficial, a pump using the wave cam drive system with comparable competitive performance may be housed within a smaller hand held spray bottle or spray wand applicator, saving weight and improving the user experience. [0066] While various embodiments have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the function and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the embodiments described herein. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, embodiments may be practiced otherwise than as specifically described and claimed. Embodiments of the present disclosure are directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present disclosure.