Abstract:
A shoulder supported, hand directed automotive grease gun in which a reciprocating piston transfers fluid from a supply tube to an outlet conduit. A battery powered motor and gear transmission rotate a disc on which is mounted an eccentric pin. The pin forcibly moves a piston holder between low friction parallel guides so as to advance the piston with its transferred fluid toward the outlet conduit. A first spring constantly biases the piston holder toward the pin so that the piston reciprocates rapidly as the disc rotates. An adjustable spring-loaded ball seal unit with an adjustable spring seat controls flow of the fluid. A fluid supply tube heating device alters fluid density to also control fluid flow. An auxiliary shoulder strap relieves pressure on an operator&#39;s wrist and transfers backpressure and tool weight to the operators body.

Description:
REFERENCE TO RELATED APPLICATIONS  
       [0001]     Not applicable  
       REFERENCE TO SEQUENCE LISTING  
       [0002]     Not applicable  
       BACKGROUND OF THE INVENTION  
       [0003]     1. Field of the Invention  
         [0004]     The invention disclosed and claimed herein relates to battery powered, hand manipulated fluid dispensing tools of the type typically referred to as grease guns, and more particularly to a cam and piston fluid ejection system acting against an adjustable check valve to control output.  
         [0005]     2. Description of the Related Art  
         [0006]     Hand manipulated fluid dispensers of the type employed as grease guns and the like generally include fluid pumps driven by power transmission systems including DC motors and associated power output gearing systems. Typically, as a final power transmission segment, a reciprocating piston or plunger interconnected to or engaged by the power transmission system acts in a first direction along a passageway to rapidly eject fluid, e.g., grease. The fluid exits by force through an outlet and into a tool outlet conduit leading to a delivery target location. In its second, or opposite, direction the piston or plunger permits fluid to exit a fluid supply container into the passageway for subsequent ejection.  
         [0007]     In general, portable grease guns and the like include three overall tool components which may be present in a variety of mechanical formulations. First is the mechanical component where a rotational movement produced as output from a motor and its associated gearing is transformed to substantially linear reciprocal pumping movement causing a piston or plunger element to present a rapid pressurized force to eject the fluid.  
         [0008]     The second component is the power generation and transmission system, itself, including a DC motor and associated gear set or motor output system. The third principal component of portable grease guns and the like is a handle, typically including an on/off power switch, a suitably configured hand-grip portion, and a power source (e.g., battery) often enclosed within a handle cavity. Again, typically, the battery power source may of the rechargeable type.  
         [0009]     Additional components beyond the three just described may include a fluid material supply chamber in the form of a hollow housing (e.g., tubular in shape) adapted to be fitted with a charge or reservoir of fluid (e.g., grease) which itself may be contained within a tubular insert element. This charge is configured and positioned so as to deliver fluid material on demand to a charging area passageway where the reciprocating piston or plunger acts to eject it through a pumping action. A fluid material supply chamber may be tubular in shape, and may also be equipped with an internal spring-biased feeding plunger ensuring a consistent and continuous discharge of fluid into the charging area passageway.  
         [0010]     Prior art portable fluid ejection or dispensing systems frequently include external delivery conduits or hoses with remote terminal fittings at their distal ends where ejected fluid, e.g. grease, is to be delivered or deposited under pressure. The hoses may generally be adapted to have proximal ends suitably connected to the dispensing tools adjacent their fluid exit openings, and configured to receive fluid expelled under the ejection force of the reciprocating pistons or plungers.  
         [0011]     Closure seals for said exit openings may be biased into a closed position by spring elements so as to keep the exit openings closed when not forced open by the pumping movement of the piston. A typical seal may involve a ball element contained within a discrete sealing unit that is fastened in place by an externally accessible bolt or screw plug.  
         [0012]     The patent granted to Post et al., U.S. Pat. No. 6,135,327 illustrates a battery operated liquid dispenser having a top mounted, battery powered motor. The motor in the Post et al. dispenser operates through a set of gears to move a yoke with an external slot. A plunger for ejecting fluid has a head retained in the slot such that the plunger is moved relative to the yoke and dispenses fluid under pressure.  
         [0013]     The Post et al. patent also shows a ball check valve assembly serving as a closure seal, and held in place by a threaded plug. The ball check valve itself is biased by a seal spring. The plug serves to secure the check valve assembly in place, but is not adapted to adjust biasing pressure of the spring. The plunger, engaged by the yoke reciprocates to discharge fluid counter to the biased the closure seal.  
         [0014]     In the Orlitzky et al. U.S. Pat. No. 6,408,985, another motor driven lubricator system is shown. In this disclosure, lubricant fluid is received and held in a chamber having an outlet. A movable member is part of a crank mechanism by which a movable member is moved toward the outlet to force lubricant therefrom.  
         [0015]     Shih, et al., in their U.S. Pat. No. 5,609,274, show a portable grease dispensing device with a supply tube and a handle, wherein the driving unit has a rotatable output shaft and linkage unit interconnecting the shaft and a push rod so as to convert rotary motion of the shaft into reciprocating motion of the push rod.  
         [0016]     Barry&#39;s U.S. Pat. No. 5,685,462 teaches an extruding apparatus with a feeder piston that extrudes fluid from a cylinder. The piston is moved by a throw mounted to a crank. Further disclosed by Barry is a fluid supply chamber in the form of a hollow housing having an inserted tube including a fluid charge. A spring element adds a biasing pressure against a feeding plunger.  
         [0017]     Huang et al., in their Published U.S. patent application No. 2004/0231927, illustrate and describe another battery operated grease gun. This gun includes an electronic pressure regulator for controlling pressure of the grease. Also described is a pump system consisting of an eccentric pin-driven sliding block which, in turn, drives a reciprocating plunger. Huang et al. also describe a lubricant reservoir in the form of a cylindrical housing.  
         [0018]     While the above discussed patent references clearly relate to the instant invention disclosed and claimed herein, none has the distinguishing features to be discussed below. In particular, and despite many years of incremental development in this field, the prior art suffers from relatively high friction mechanisms and a disregard for the need for important adjustability features to ensure smooth and ready delivery of fluid on demand. Additionally, prior art fluid ejection tools too often are far too delicate in mechanical design. Specifically, their point of failure most often lies in the mechanism for transferring rotary motion of reduction gearing to linear motion of the fluid ejection piston or plunger. This is especially a problem in ejection tools where no adjustment means is available to the user to accommodate field conditions.  
       SUMMARY OF THE INVENTION  
       [0019]     A principal objective of the present invention is to provide a portable grease gun that will have a power source, e.g., rechargeable battery, and with a fluid pumping mechanism in the form of a more efficient and effective pump plunger drive system. This system includes a low friction eccentric pin uniquely engaging a stable, robust spring biased plunger-holding device, so as to ensure a highly dependable and durable, yet relatively low cost, system.  
         [0020]     A further objective is to manage fluid output or ejection pressure as operating conditions of such a tool may demand, and to do this through a combination of adjustment features including a biased ball seal passage closure unit, as well as heating elements within the fluid reservoir housing. A still further objective is to make such a tool principally shoulder supported and hand directed, by furnishing it with a unique shoulder strap element to shift the weight and backlash forces away from the user&#39;s wrist to thus avoid discomfort and painful injuries.  
         [0021]     Other objects, features, and characteristics of the present invention will become apparent upon consideration of the following full description and the appended claims, with reference to the accompanying drawings, wherein like reference numerals designate corresponding elements in the various figures. 
     
    
     BRIEF SUMMARY OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0022]     Referring now to the accompanying drawings, constituting a part hereof, and with like reference characters indicating like parts, it is seen that:  
         [0023]      FIG. 1  is a side elevation view of the fluid dispensing tool of the present invention;  
         [0024]      FIG. 2  is a top perspective view of the fluid dispensing tool of the present invention;  
         [0025]      FIG. 3  is a side elevation view similar to  FIG. 1 , and with a portion of the handle and motor housing removed to facilitate viewing internal elements;  
         [0026]      FIG. 4  is a side view showing only the motor housing and gearing arrangement for the fluid dispensing tool of the present invention;  
         [0027]      FIG. 5  is an elevation view of the motor housing and gearing arrangement of the present invention;  
         [0028]      FIG. 6  is a top plan view of the fluid dispensing tool of the present invention with a portion of the housing enclosure removed revealing the pin driven piston arrangement;  
         [0029]      FIG. 7  is a top perspective view further illustrating the eccentric pin driven piston arrangement along with such external details of a hose fitting and bleeder of the present invention;  
         [0030]      FIG. 8  is a view similar to  FIG. 7 , but showing a pin sleeve element removed for clarity;  
         [0031]      FIG. 9  is a perspective view of pin sleeve and plunger along with associated parts shown as disassembled for clarity;  
         [0032]      FIG. 10  is a sectional view of the fluid dispensing tool of the present invention, showing the interrelationship of certain moving parts, including gearing, eccentric pin/piston arrangement, and check valve elements;  
         [0033]      FIG. 11  is a sectional view similar to that illustrated in  FIG. 10 , but with a portion enlarged to show clearly the details of the check valve ball and spring elements, as well as unique adjustment features;  
         [0034]      FIG. 12  is an exploded perspective view of the present invention with details of the check valve ball and spring assembly, particularly illustrating the adjustable features of the present invention, and with certain assembly elements illustrated in an exploded view labeled as “a;”  
         [0035]      FIG. 12   a  is an enlarged perspective of the certain assembly elements from view “a” in  FIG. 12 ;  
         [0036]      FIG. 13  is a side elevation of the present invention, and in particular illustrating the fluid storage features;  
         [0037]      FIG. 14  is a side elevation of the tubular-shaped fluid storage housing;  
         [0038]      FIG. 15  is a cross-sectional view of the storage housing of  FIG. 14  wherein the section is taken at A—A, and in particular illustrating a heating element therein.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0039]     It should be appreciated that the tool described as the present invention can have a number of applications, and that reference to grease gun or grease fluid is merely an economy of expression in the interest of efficiency and brevity. Thus, this reference in the title and description is without intent to limit the invention scope or in any respect to exclude equivalents.  
         [0040]     In terms of an operating system, the present invention includes four main work portions. Viewing  FIG. 1 , it is apparent that these main portions include a handle grip  9  a power supply, along with a power and transmission system shown generally at  7 , fluid (e.g., grease) supply source or container  6  and tool output conduit  4 . The handle grip  9  further includes an on-off switch  2 .  
         [0041]     To accommodate tool weight and backpressure forces during fluid delivery, an auxiliary shoulder belt or strap  1  is suitably attached to the handle grip  9 . Extended periods of wielding such a portable device can be exhausting, given its weight, vibratory characteristics and inherent backlash or back pressure. Besides, the constant twisting effect on an operator&#39;s wrist can cause injury.  
         [0042]     The shoulder strap  1  offers stress relief by shifting a major portion of tool weight and backlash to the operator&#39;s body. In other words, the tool becomes shoulder -supported and hand-directed. By facilitating the operator&#39;s application of shoulder strength and body weight, this shoulder belt  1  works in conjunction with other fluid flow management (to be described in detail herebelow) to deliver a smoother and more effective discharge, and with less effort and chance of injury.  
         [0043]     Stored within or directly adjacent handle grip  9  is a power source, shown at  8 . The power source  8  is chosen from a variety of widely available rechargeable battery power units and assigned the primary role of powering DC motor  12  shown in  FIG. 3 . A tool outlet conduit or hose  4  is attached at a proximate end to a fluid exit, to be further described herebelow, and includes a suitable fitting  5  at the distal end thereof whereby fluid, e.g., lubricant, may be directed for targeted delivery. Additional conventional features are illustrated in  FIG. 2 , including a bleeder tap  10  and filler port  11 .  
         [0044]     Driven by DC motor  12 , as illustrated in  FIGS. 4 and 5 , are a series or train of reduction and transmission gears illustrated at  15 ,  13 ,  14 , and  16 . At this point the tool drive and transmission system serves to operate the fluid pumping mechanism, where motion is converted from rotary to linear. To this end, the output of gear  16  rotatably engages disc 17  which is adapted to rotate about its central axis.  
         [0045]     Attached or otherwise affixed to said disc is pin  18  which is eccentric, or spaced from said central axis. A low-friction sleeve  19  composed of well known low friction material is shown in  FIGS. 6, 7  and  8  substantially covers pin  18 . Sleeve  19  is mounted on pin  18  so as to be rotatable on its own axis when in moving engagement with piston holder  20  to be described as follows.  
         [0046]     Pin  18 , through its rotatable, substantially non-friction sleeve  19 , directly engages a piston holder  20 , itself machined, constructed and/or coated so as to present low friction characteristics. Piston  21  is suitably interconnected or attached at a first end thereof, for example by a threaded connection or the like, to piston holder  20  as is further illustrated in  FIG. 9 . Of course, said piston could be integral with said holder, as well. A second end of said piston  21  extends into housing passageway as will be described.  
         [0047]     Surrounding piston  21  is a first compression spring  22 . Spring  22  has a first end engaging piston holder  20  at a point on holder surface  36  where piston  21  is attached or otherwise interconnected to said holder. A second end of said first spring  22  engages said tool housing  34  at a point where said piston enters a housing passageway, so as to continuously and flexibly bias holder  20  toward pin  18 .  
         [0048]     Biased by first spring  22  toward pin  18 , piston holder  20  is thus moved in one direction by the force of the eccentric pin  18  mounted on rotating disc  17  and returned in its rapid reciprocal path by the force of spring  22 . Piston holder  20  is adapted to slidably fit between parallel guide portions  23  and  24  of said tool housing, viewed as part of the tool housing (see  FIG. 12 ). Importantly, such guide portions  23  and  24  along with piston holder  20  include substantially non-friction bearing surfaces. Thus, piston holder  20  is confined and stabilized in its rapid reciprocating motion by said parallel guide portions  23 ,  24 .  
         [0049]     With this elegantly simple, low cost and low friction mechanical design for the fluid pumping mechanism, piston  21  is thus driven along a pathway or passageway adjacent said fluid supply source so as to push fluid exiting said supply source toward said tool outlet conduit.  
         [0050]     Most power loss in existing fluid pumping systems has been experienced at the point where rotary motion is converted to the reciprocal dispensing motion. Through the use of this novel, low friction pin-driven piston holder system, the fluid injection or dispensing tool described herein operates more efficiently than the prior art systems.  
         [0051]     The guided, confined motion of the piston holder between guides  23  and  24 , coupled with the steadying or stabilizing effect of the first compression spring  22 , reduces damaging vibration and misalignment of moving parts found to be common in past configurations. Additionally, the first compression spring  22  works cooperatively with a second compression spring within a check valve spring adjustment system to be described as follows.  
         [0052]      FIG. 10  illustrates an exit where fluid material would emerge from its reservoir within fluid supply source container  6  (removed in this view) through a reduced nozzle area  37  and into an output zone (or piston passageway)  38  to be impinged upon by the reciprocating piston  21 . As the piston moves along a pathway to the right as viewed in  FIG. 10 , it imparts a rapidly repeated pressure to the fluid, rapidly pressing said fluid under an ejection force toward tool outlet conduit  4  attached at its proximate end at a fluid exit area of the tool housing  
         [0053]     A ball seal unit is positioned along said passageway between said piston  21  and said tool outlet conduit  4 , and adapted to block said passageway between said piston and said tool outlet conduit. Said ball seal unit including as a component thereof a blocking ball  25  biased by second compression spring  26 . The term “ball” in the context of, and within the scope of the appended claims, is meant to extend to ball-like, rounded, substantially spherical or hemispherical surfaces.  
         [0054]     Said second compression spring is shown as seated against a spring seat  28 , as best viewed in  FIGS. 11, 12  and  12   a . Thus, the exit area is normally blocked by sealing ball  25  biased against the fluid material flow by spring  26 . Spring  26  is positioned within the ball seal unit between ball seal  25  and O-ring  27  pressed against seat  28 .  
         [0055]     Typical of prior art devices of this type, the pressure provided by a ball seal mechanism is pre-set at the factory. While different settings of such a mechanism will determine the output pressure of fluid being delivered to the target, there is no ready way to adjust this pressure (post-assembly) while in the field according to present needs, conditions of the surrounding environment, fluid characteristics and delivery requirements. The present invention successfully addresses this shortcoming in the prior art, and in a way that uniquely combines with other adjustment features of the present invention.  
         [0056]     The ball seal  25 , its spring  26  and O-ring  27  are held in place by a valve bolt  3 , threaded (not shown) in a conventional manner to the tool housing (see  FIG. 11 ). The pressured fluid forces ball seal  25  to compress its biasing spring  26  against O-ring  27  and seat  28  to a point (or position) where the fluid exits. Of course, the rapid movement of plunger  21  produces the effect of a substantially continuous flow of fluid exiting through conduit  4  as long as the tool operator engages the trigger switch  2 .  
         [0057]     Experience has shown, however, that differences or changes in viscosity or other flow characteristics of the fluid to be ejected or discharged can pose problems in obtaining desirable output volume and/or pressure. For example, surrounding temperatures can have either a softening or hardening effect on the fluid to be pumped. Where the fluid is less dense or more flowable, a considerable amount, too much in fact, may be ejected with bad results with respect to the work being performed.  
         [0058]     On the other hand, when the fluid is dense and insufficiently flowable a considerable amount of power may be drawn so as to deplete the battery. Beyond that the tool may be damaged from the severe pressures involved. To address such problems, the present invention includes a unique adjustment mechanism as illustrated in  FIGS. 11, 12  and  12   a . Valve bolt  3  includes an internal adjustable lug  29 . Adjustment lug  29  is generally protected by cover  30 , and is fitted within valve bolt  3  by a conventionally internal threaded connection, not shown.  
         [0059]     At its outermost end, adjustable lug  29  is provided with a slot, accessible when cover  30  is removed, and adapted to be engaged by a conventional adjusting element such as a screwdriver and the like. Of course, a variety of other, equivalent configurations could be employed to reach the same end. For example, adjustable lug  29  could have an externally extended head provided with two or more flattened portions to be engaged by a wrench.  
         [0060]     When conditions require an adjustment to the flow of fluid such as grease and the like, to permit either an increased flow rate or reduced flow rate, the cover  30  is removed and a tool is applied to turn lug  29 . The turning of lug  29  serves to move the seat  28  such that it de-compresses or compresses spring  26 . Thus, the resistive force of ball seal  25  is adjusted accordingly.  
         [0061]     By adjusting the spring seat  28  position, the operator achieves a desired preload on the spring  26 ; and, thus the operator achieves a desired exit pressure or flow by selectively countering the ejection force of the plunger. This is because a large preload will require a higher pressure to move the ball seal  25 . Exiting fluid generally is delivered under high pressure. Less preload or pre-set resistance, of course, will result in a lower fluid pressure at exit. Working in conjunction with the compression spring  22 , spring  26  provides a remarkably effective dampening effect, and considerable control of the flow of the fluid through and out of the tool.  
         [0062]     Another feature of the present invention further addresses the problem of fluid viscosity changes, particularly in colder climes where stiffening or solidifying of the fluid results in an increased density. The increased density, in turn, brings about constricted fluid flow and reduction of working efficiency.  
         [0063]     As discussed above, when the fluid resists movement along its intended pathway, less fluid material is expelled and more battery power is consumed, causing increased battery drain. Similarly, increased work demand imposes a strain on the DC motor, reducing its operational life. Likewise, the operator must struggle against the backpressure in the tool&#39;s passageways, and work against the clock to get the job done in a timely manner.  
         [0064]     To address this problem, the present invention modifies the grease supply source. This modified tube is shown as tube  31  in  FIGS. 13-15 . Tube  31  is fitted with an internal heating element in the form of a layer of wiring  32 . This heating element itself may take a tubular configuration. The heating element may include a wire mesh construction  32  and/or have a metal foil material covering  33 .  
         [0065]     A fluid supply tube would be placed within said tube  31 , and the wiring is selectively connected to battery  8  such that the wiring is caused to be heated. Heat from the wiring maintains a more workable density in the fluid flow.  
         [0066]     Upon careful reading of the foregoing specification and the accompanying drawings, it will be evident that this invention is susceptible of modifications, combinations, and alterations in a number of ways which may differ from those set forth. The particular arrangements disclosed herein are intended as illustrative only and in no way limiting as to the scope of the invention which is to be given full breadth of claims appended hereto and any and all equivalents thereof. What is claimed is: