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1. Field of the Invention
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.
2. Description of the Related Art
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Barry'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.
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.
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.
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.
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's wrist to thus avoid discomfort and painful injuries.
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.
Referring now to the accompanying drawings, constituting a part hereof, and with like reference characters indicating like parts, it is seen that:
a is an enlarged perspective of the certain assembly elements from view “a” in
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.
In terms of an operating system, the present invention includes four main work portions. Viewing
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's wrist can cause injury.
The shoulder strap 1 offers stress relief by shifting a major portion of tool weight and backlash to the operator's body. In other words, the tool becomes shoulder -supported and hand-directed. By facilitating the operator'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.
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
Driven by DC motor 12, as illustrated in
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
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
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.
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
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.
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.
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.
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.
Said second compression spring is shown as seated against a spring seat 28, as best viewed in
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.
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
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.
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
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.
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.
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.
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.
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's passageways, and work against the clock to get the job done in a timely manner.
To address this problem, the present invention modifies the grease supply source. This modified tube is shown as tube 31 in
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.
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: