WO1993017274A1

WO1993017274A1 - Lubricant gun

Info

Publication number: WO1993017274A1
Application number: PCT/GB1993/000379
Authority: WO
Inventors: Derek Sydney Izzard
Original assignee: Derek Sydney Izzard
Priority date: 1992-02-26
Filing date: 1993-02-24
Publication date: 1993-09-02
Also published as: AU3571193A

Abstract

A lubricant gun of the kind having a reciprocating piston pump (13, 15) which forces lubricant supplied to the pump from a lubricant container (2) to an outlet (7), characterised by a lubricant inlet (18, 19) to the pump disposed in the cylinder (13) at or near the outermost end of the piston travel and controlled by a valve (11, 12, 36, 37).

Description

TITLE: LUBRICANT GUN DESCRIPTION

TECHNICAL FIELD

The invention relates to lubricant guns, that is to say devices from which a lubricant such as grease or oil is dispensed under pressure to lubricate bearing surfaces and the like of machinery. Such a lubricant gun has a reciprocating piston pump which forces lubricant supplied to the pump from a lubricant container to a dispensing outlet.

BACKGROUND ART

A device of this general kind is described in the specification of GB 1210199 of Metabowerke KG Closs, Rauch

& Schnizler, and the specification discloses that the piston pump may be driven by an electric motor.

I have discovered that there may in some circumstances be a tendency in operating a lubricant gun of the kind having a reciprocating piston pump for a vacuum or partial vacuum to form in the chamber or chambers of the pump which results in a loss of pumping efficiency and/or in the formation of so called "air locks".

It is an object of the invention to avoid or mitigate such occurrences by reducing the tendency for the formation of a vacuum.

DISCLOSURE OF INVENTION

According to the invention there is provided a lubricant gun of the kind having a reciprocating piston pump which forces lubricant supplied to the pump from a lubricant container to an outlet, characterised by a lubricant inlet to the pump disposed in the cylinder at or near the outermost end of the piston travel and controlled by a one-way valve. A lubricant outlet from the pump will preferably also be disposed at the outermost end of the cylinder. This arrangement is in contrast to the known arrangements in which the lubricant inlet to the cylinder is remote from the outer end of the cylinder and in which the leading end of the piston is itself effective to shut off and open the lubricant inlet.

Preferably the pump will be a double-acting reciprocating piston pump. A single double-headed piston may be employed or alternatively a pair of free pistons may be employed. In the latter case the pistons may be moved outwardly under the action of a cam or eccentric and may be returned by resilient means, e.g compression springs.

The lubricant gun may comprise an electrically operated pump. The pump may be driven by a DC electric motor which can be powered from an electric battery, e.g. an accumulator of a vehicle or machine to be serviced or by a battery, e.g. a rechargeable dry-cell battery, contained perhaps in the lubricant gun or in a separate powerpack carried by the user on a waist band.

The lubricant gun may be in the form of a hand-held tool comprising a lubricant container, which may be under pressure from resilient means such as a spring in conventional manner, reciprocating piston pump means, an electric motor driving the pump, means for delivering the lubricant to a dispensing outlet nipple and means connecting the electric motor to an electric battery or accumulator.

The device will preferably comprise a pressure relief valve in the lubricant delivery system, and preferably a pressure switch will be provided to shut off, and thus protect, the electric motor in the event of pressure overload in the system.

BRIEF DESCRIPTION OF DRAWINGS

The invention is diagrammatically illustrated, by way of example, in the accompanying drawings, in which:-

Figure 1 is a general side view of a portable lubricant gun, showing the pump driving mechanism in dotted lines;

Figure 2 is a cross-sectional side view through a preferred form of reciprocating piston pump;

Figure 3 is a cross-sectional view of the pump of Figure 2 and taken on the line 3-3 of Figure 2;

Figure 4 is a cross-sectional side view, similar to that of Figure 2, through a second embodiment of reciprocating piston pump, and

Figure 5 is a cross-sectional side view, similar to that of Figure 2, through a third embodiment of reciprocating piston pump.

BEST MODES FOR CARRYING OUT THE INVENTION

In the drawings there is shown a high pressure lubricant gun, e.g. for dispensing grease or oil, of the kind comprising a reciprocating piston pump which forces lubricant supplied to the pump from a lubricant container or reservoir to a dispensing outlet.

As shown in Figure 1 of the drawings a lubricant gun 1 comprises a generally cylindrical lubricant container or receptacle 2 adapted, in conventional fashion, to hold a cartridge of grease or oil (not shown) and to apply pressure to the lubricant by means of a spring or the like (not shown) to force the lubricant to a pump 8 described below. The container 2 is secured to a pump body 9 by means of a releasable coupling, (not shown) e.g. screw- threaded means. The pump body 9 contains a reciprocating piston pump more particularly described below with reference to Figures 2 and 3. The pump in the body 9 is actuated by means of an electric motor 3 which is mounted on the pump body 9 and a handle 4 is mounted on the casing of the electric motor to assist in the handling and manipulation of the gun. A flexible lubricant delivery hose or pipe 6 extends from the pump body and is terminated in conventional fashion by a dispensing outlet or connector 7.

The pump 8 comprises a body 9 made for example from aluminium and having a substantially centrally disposed cylindrical cavity 14 defining a cylinder 13, containing a cylindrical member 15 defining at its opposite ends an opposed pair of pistons 16,17. The cylindrical member 15 is a snug fit in the cylinder 13 and is slidable axially therein. The cylindrical member 15 is formed centrally with a recess 34 snugly containing an assembly consisting of a circular drive member or eccentric 31 and a bearing 32 mounted eccentrically on a drive shaft 30 journalled in bearing 33 in the body 9 whereby rotation of the shaft 30 causes the pistons 16,17 to reciprocate in the cylinder 13. Lubricant from the container 2 enters the pump body 9 through an inlet cavity 10 and communicates with an opposed pair of cylinder inlets 18,19 disposed at the outer ends of the cylinder 13, via respective non-return valves 11,12, each of which comprises a ball urged against a seat by spring means in conventional manner.

Lubricant leaves the cylinder 13 via under pressure through a pair of outlets 21 disposed at the outer ends of the cylinder 13 and exits the body 9 through a common outlet 23 via a common non-return or shuttle valve 22 consisting of a ball which is movable under lubricant pressure to seat in either one of an opposite pair of orifices communicating with the outlets 21. The outlet 23 communicates with hose 6 in conventional fashion. A pressure relief valve 24 is provided in the outlet downstream of the shuttle valve 22 to vent lubricant back to the container 2 via an outlet 25 in the event of over¬ pressure in the system.

The pump arrangement described in Figure 4 is very similar to that described above with reference to Figures 2 and 3 with the exception that the cylindrical member 15 is replaced by a pair of free pistons I5a,15b which are held in contact with the eccentric assembly 31,32 by compression springs 35. In the arrangement of Figure 5, which is generally similar to that of Figures 2 and 3, the one way valves 11,12 are replaced by piston controlled lubricant inlet ports 36, and to avoid or mitigate the formation of vacuum in the cylinder 13 above the pistons, the sides of the pistons near to their tops are cut away at 37 to form flow paths for the lubricant so that the ports 36 are uncovered or opened early in the pump cycle. Thus the sides of the pistons may be formed with small grooves extending to the tops of the pistons to form the lubricant flow paths.

In a further modified arrangement not shown in the drawings, lubricant may be fed to the cylinder 13 through inlet ports extending longitudinally through the cylindrical member 15 and fed with lubricant e.g. from a centrally disposed opening in the side of the cylindrical member 15 and through a registering inlet port in the body 9 and opening into the cylinder 13. The inlet ports in the member 15 would open at each end into the cylinder through the piston tops and would be controlled by an opposed pair of one-way valves, e.g. ball valves, disposed in the cylindrical member 15.

It will be appreciated that although the invention has been described with reference to a lubricant pump, the apparatus of the invention could be used to dispense other liquids, gels and semi-solids.

INDUSTRIAL APPLICABILITY

The pump arrangements described above permit a lubricant gun to be operated with a modest power consumption and thus permits the gun to be operated as a self powered hand tool.

Claims

1. A lubricant gun of the kind having a reciprocating piston pump (13,15) which forces lubricant supplied to the pump from a lubricant container (2) to an outlet (7) , characterised by a lubricant inlet (18,19) to the pump disposed in the cylinder (13) at or near the outermost end of the piston travel and controlled by a valve (11,12,36,37) .

2. A lubricant gun according to claim 1, characterised by a double-acting reciprocating piston pump (16,17).

3. A lubricant gun according to claim 1 or claim 2, characterised in that the pump (13,15) is driven by a DC electric motor (3) powered from an electric battery, whereby the lubricant gun is in the form of a hand-held self contained tool.

4. A lubricant gun according to any one of claims 1 to 3, characterised by a pressure relief valve (24) in the lubricant outlet (21) to vent lubricant into the container (2) on over-pressure.

5. A lubricant gun according to any preceding claim, characterised in that the lubricant inlet (18,19) is controlled by a one way valve (11,12) .

6. A lubricant gun according to any one of claims 1 to 4, characterised in that the lubricant inlet (36) is controlled by the piston (15) and characterised in that the sides of the pistons (16,17) are formed near to their tops with lubricant paths (37) whereby the inlets (36) are uncovered early to reduce formation of vacuum in the cylinder (13)