GB2525503A

GB2525503A - Method of fitting a grease cartridge to a vacuum grease gun

Info

Publication number: GB2525503A
Application number: GB1505661.7A
Authority: GB
Inventors: Michael Horace Gregory
Original assignee: LUMETER Ltd
Current assignee: LUMETER Ltd
Priority date: 2015-04-01
Filing date: 2015-04-01
Publication date: 2015-10-28
Anticipated expiration: 2035-04-01
Also published as: GB2525503B; GB201505661D0

Abstract

A method of fitting a grease cartridge 10 to a greasing head 100 with an associated barrel 26 and end cap 32; the barrel attaches to the greasing head at a first end 28 and the end cap attaches to the barrel at a second end 30, and the cartridge is enclosed within the barrel and end cap arrangement. The grease cartridge is longer than the length of the barrel, such that when inserted into the barrel it protrudes from the second end, and fitting of the end cap clamps the cartridge in place against the greasing head by use of a cooperating screw thread on the barrel 34 and within the end cap. The arrangement also includes a follower seal (16 Fig. 2) which provides an airtight seal for the grease cartridge, allowing vacuum dispensing of grease. The follower seal can be integral with the cartridge or it can be removable and re-used. An aperture may be provided in the end cap so that pressure can be applied to the follower seal in order to prime the greasing head. The greasing head can be part of a grease gun, and in particular a vacuum-type grease gun.

Description

METHOD OF FITTING A GREASE CARTRIDGE TO A GREASE GUN

The present invention relates to a method of fitting a grease cartridge to a grease gun head. In particular, the method of the invention allows a standard grease gun cartridge to be used with a greasing head, to discharge the grease by the vacuum principle, without the use of a spring.

BACKGROUND TO THE INVENTION

Grease guns are used to dispense grease for lubrication of mechanical parts. Grease guns include a greasing head and a barrel for storing grease. The most common type has a spring and a plunger which pushes against a body of grease packed into the barrel, to push grease out of the greasing head. Spring-plunger grease guns have a straightforward mechanism, but there are certain disadvantages associated with their use. The spring can sometimes become damaged and lock', preventing release. Releasing the spring can also sometimes be a cause of injury) and another safety issue is that fingers can be trapped between the release handle and the end of the barrel.

Vacuum grease guns are also available, and have benefits in certain applications. Known vacuum' grease guns are for use with specialised cartridges. A vacuum-type grease gun works by creating a vacuum at the grease head, to draw grease out of the barrel. Vacuum-type guns are more compact, because there is no push-rod which needs to extend from the grease barrel. Also, grease guns which use the vacuum principle and therefore do not require a spring can be stored ready for use, because the stored grease is not under any pressure when the gun is not being operated. In contrast, in a spring-plunger gun, the spring pressure has to be released when the gun is not in use) because otherwise the pressurized grease can bleed oil.

Vacuum grease guns use substantially the same type of greasing head as spring-plunger guns, but have no spring and plunger. Instead, a follower seal is provided in place of the plunger, behind the grease to be dispensed, forming a seal between the grease and the atmosphere.

Spring-plunger grease guns are available with refillable barrels, which can be bulk-filled from kegs of grease. However, refilling a grease gun with grease is a time-consuming and messy procedure.

Commercial users therefore generally prefer to use grease cartridges, which are available in standard sizes for spring-plunger guns. The cartridge is in the form of a cylindrical sleeve, open at both ends and filled with grease. The cartridge is loaded into the gun with one end facing the greasing head, and the plunger is introduced into the other end and used to push grease out of the cartridge and through the greasing head. When the cartridge is empty, it is discarded and replaced with a new, ready-filled cartridge.

Grease cartridges are also available for emptying by the vacuum principle. One advantage of discharging grease by the vacuum principle is that the cartridge can be completely emptied, eliminating waste. This is in contrast to a spring-plunger gun, where typically a small amount of grease will be left in the cartridge which cannot be dispensed. However, known cartridges for vacuum-principle discharging include a screw-fitting at one end of the cartridge, for attaching and sealing the cartridge to the greasing head. This is necessary because in a grease gun which is to operate on the vacuum principle) with no spring) there is nothing to hold the cartridge in place from the rear end, which is a function provided by the barrel) spring and plunger in a spring-plunger gun.

The screw-fitting and the need to supply a follower seal makes these cartridges more expensive to buy. In addition, there is currently no standard fitting for cartridges for vacuum-principle discharge) and so generally users have no option but to buy both the grease gun and the matching grease cartridges from the same manufacture) if they wish to take advantage of the benefits of vacuum-principle discharge.

A completely airtight seal is not strictly necessary for a spring-plunger gun to work. However) if air is able to enter the system between the end of the cartridge and the greasing head, then the amount of grease dispensed with each pull of the trigger may not be uniform. This can be a problem in some applications, where a carefully-controlled amount of grease is required.

It is an object of the invention to solve the above-mentioned problems) by providing a method of fitting a standard grease cartridge to a grease gun head, for vacuum-principle discharge.

STATEMENT OF INVENTION

According to the present invention, there is provided a method of fitting a standard grease cartridge to a greasing head, the method comprising the steps of: providing a barrel, the barrel having means for attaching the greasing head at a first end, and means for attaching an end cap at a second end; attaching the barrel at the first end to the greasing head; inserting a grease cartridge into the barrel, the length of the grease cartridge being longer than the distance between the greasing head and the second end of the barrel, so that a first end of the grease cartridge abuts the greasing head and a second end protrudes from the second end of the barrel; providing a follower seal and inserting the follower seal into the second end of the grease cartridge; attaching an end cap to the second end of the barrel, so that the end cap bears against the second end of the grease cartridge and applies a force to the second end of the grease cartridge, sealing the first end of the grease cartridge against the greasing head.

The greasing head will typically include an 0' ring seal, and so as the end cap pushes the cartridge against the greasing head, an airtight seal will be formed between the cartridge and the greasing head.

The greasing head may be any of a variety of different types. In particular the method of the invention may be applied to manual, pneumatic or battery operated greasing heads.

The method is advantageous, because the grease cartridges used may be ordinary standard-sized cartridges, designed for spring-follower guns, with no special fittings. These grease cartridges are in the form of hollow tubes with two open ends. These standard cartridges are available at low cost from multiple suppliers, and the method of the invention allows them to be discharged by the vacuum principle, using greasing heads which were originally intended for use with a spring and plunger. For vacuum principle discharge, a sealed connection must be provided between the greasing head and the cartridge, at one end of the cartridge, allowing grease to be sucked out of the cartridge when the greasing head is operated.

A DIN 1284 grease cartridge is 235 to 239mm long. Therefore, the barrel may be around 233mm long. In practice, depending on the design of the greasing head, the cartridge may or may not protrude slightly beyond the first end of the barrel to abut the 0' ring seal in the greasing head, and therefore the amount of protrusion of the cartridge from the second end of the barrel may be slightly less than the difference between the length of the barrel and the length of the cartridge.

The small protrusion allows force to be applied to the second end of the grease cartridge by the end cap. In a preferred embodiment, the barrel is externally screw threaded at the second end and the end cap screws onto the barrel. A screw fitting is advantageous because the end cap can be tightened to apply the required force against the second end of the grease cartridge, simply by screwing the end cap an appropriate distance onto the thread of the barrel.

The end cap is typically in the form of an end plate and a circular wall extending perpendicularly from a periphery of the end plate. The extent of the circular wall may be, for example, 12mm - 20mm. The circular wall may be threaded internally, preferably along substantially its entire extent.

The end cap can be firmly attached to the barrel when it is screwed, for example, at least 5mm onto the thread of the barrel. Therefore a 10mm -20mm thread on the end cap provides a good 5mm- 15mm tolerance, allowing the equipment to be used with cartridges of slightly different lengths, and with different greasing heads.

Preferably) an aperture is provided in the end cap. This is typically provided substantially at the centre of the end plate. The aperture is used to apply a force to the follower seal when priming the gun.

The purpose of the follower seal is to provide an airtight seal in the grease cartridge, allowing the vacuum system to work. The follower seal is inserted into the second end of the grease cartridge, and is pushed against the body of grease which is packed into the cartridge. As grease is dispensed by the vacuum system, the follower seal will be drawn along the cartridge, until the grease cartridge is empty at which point the follower seal will stop against the greasing head. It is then easy to remove the follower seal and re-use it with a new grease cartridge.

The follower seal is preferably rigid at the centre, and has a flexible peripheral seal. The seal may be made from, for example, flexible plastics. The rigid centre part allows the follower plate to be pushed during priming, without the risk of damaging the seal. It will be understood that the follower seal can be inserted into the grease cartridge either before or after the grease cartridge is inserted into the barrel. In some cases, grease cartridges may already include a follower seal. However, for cost savings it is preferred to provide a reusable follower seal which can be removed from a spent cartridge and inserted into a new cartridge.

According to a second aspect of the invention, there is provided a grease gun comprising a greasing head, a barrel, a grease cartridge for fitting inside the barrel, a follower seal within the cartridge, and an end cap, the barrel being attached to the greasing head at a first end and the end cap being attachable to the barrel at a second end for closing the barrel, and the grease cartridge being long enough to protrude from the second end of the barrel when the grease cartridge is inserted into the barrel and abuts the greasing head, and short enough for the end cap to be attached to the barrel when the grease cartridge is protruding from the end of the barrel.

Preferable and/or optional features of the second aspect of the invention are set out in claims 11 to 18.

DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, and to show more clearly how it may be carried into effect, preferred embodiments will now be described, by way of example only, with reference to the appended drawings, in which: Figure 1 shows a known, standard grease cartridge; Figure 2 shows a follower seal being inserted into the grease cartridge of Figure 1, as part of the method of the invention; Figure 3 shows the grease cartridge and follower seal of Figure 2 being loaded into a barrel attached to a greasing head, as part of the method of the invention; Figure 4 shows an end cap being screwed onto the loaded barrel of Figure 3, as part of the method of the invention; Figure 5 shows the loaded grease gun of Figure 4 being primed, ready for use; and Figure 6 shows five types of grease gun, loaded according to the method of the invention and ready for use.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring firstly to Figure 1, a standard sized DIN 1284 grease cartridge is indicated at 10. These cartridges are widely available, and take the form of a hollow cylinder, packed with grease. An end cap 12 and end seal 14 are typically provided, so that the grease cartridge can be stored and transported as a sealed unit. The cap 12 and seal 14 can take various forms, but in any case are removed before use, as shown in Figure 1 and indicated by arrows A, B, to leave a grease cartridge in the form of a tube which is open at both ends 22, 24.

In Figure 2, a follower seal 16 is being inserted into one end of the grease cartridge 10. The follower seal 16 is inserted into the cartridge by pushing, as indicated by arrow C. The flexible plastic follower seal 16 seals against the internal walls of the grease cartridge 10, to provide an airtight seal between the grease in the cartridge 10 and the open end 24 of the cartridge 10. The follower seal 16 can move longitudinally within the cartridge 10, whilst maintaining its sealing properties.

As shown in Figure 3, a greasing head 100 is provided with a barrel 26. The barrel is of a slightly larger diameter than the standard DIN 1284 grease cartridge 10, and is provided with an external screw thread at a first end 28, for attaching to the greasing head 100. Note that the barrel 26 must be firmly attached to the greasing head 100, but the connection does not need to be airtight. The barrel 26 is open at a second end 30, and the grease cartridge 10 with follower seal 16 can be loaded into the barrel, via the open second end 30, as indicated by arrow Din Figure 3.

Note that the barrel 26 is slightly shorter than the grease cartridge 10, such that the grease cartridge will not fully insert into the barrel 26 but will protrude slightly from the second end 30 of the barrel

S

2, as is evident in Figure 4. The protrusion is typically around 3mm, but the method will work with varying extents.

In Figure 4, an end cap 32 is screwed onto the second end 30 of the barrel 26, an external screw thread 34 being provided on the second end of the barrel. As the end cap 32 is screwed onto the barrel 26, the end cap will apply a force to the protruding end of the grease cartridge 10. This forces the first end 22 of the grease cartridge 10 against the seal in the greasing head 100, creating an air tight seal between the cartridge 10 and the greasing head 100, which allows the vacuum dispensing system to work.

Once the grease cartridge has been prepared and inserted into the barrel 26, as described above, the grease gun needs to be primed, as shown in Figure 5. Pressure is applied to the follower seal 16 in the cartridge 10, within the barrel 26, through a hole in the end cap 32, in the direction indicated by arrow E. While a force is being applied, the handle of the greasing head 100 is opened fully, and then pumped several times until grease appears from the grease coupler. The grease gun is now ready for use.

Figure 6 shows the loaded cartridge, ready for use. The grease in the greasing gun is not stored under pressure, and therefore it will not bleed oil, even if used only intermittently over a long period. The method allows this and all the other advantages of a vacuum-type grease gun, without the cost of having to obtain specialist grease cartridges, or the mess associated with refilling a refillable grease gun. The grease gun will operate consistently until all of the grease in the grease cartridge 10 is used up, at which point a new cartridge may be obtained and installed as described above. Note that the barrel, end cap and follower seal are all reusable.

Claims

CLAIMS1. A method of fitting a grease cartridge to a greasing head) the method comprising the steps of: providing a barrel, the barrel having means for attaching to the greasing head at a first end, and means for attaching an end cap at a second end; attaching the barrel at the first end to the greasing head; inserting a grease cartridge into the barrel, the length of the grease cartridge being longer than the distance between the greasing head and the second end of the barrel, so that a first end of the grease cartridge abuts the greasing head and a second end protrudes from the second end of the barrel; providing a follower seal and inserting the follower seal into the second end of the grease cartridge; attaching an end cap to the second end of the barrel, so that the end cap bears against the second end of the grease cartridge and applies a force to the second end of the grease cartridge, sealing the first end of the grease cartridge against the greasing head.
2. A method as claimed in claim 1, in which the grease cartridge is in the form of a hollow tube
3. A method as claimed in claim 1 or claim 2, in which the grease cartridge is around 2mm to 6mm longer than the barrel.
4. A method as claimed in any of the preceding claims, in which the grease cartridge protrudes from the second end of the barrel by substantially 2mm -6mm.
5. A method as claimed in any of the preceding claims, in which the means for attaching the end cap is a screw thread on each of the end cap and the barrel.
6. A method as claimed in claim 5, in which the extent of each screw thread is at least 10mm.
7. A method as claimed in any of the preceding claims, in which an aperture is provided in the end cap.
8. A method as claimed in claim 7, in which the aperture is provided substantially at the centre of the end cap.
9. A method as claimed in any of the preceding claims, in which the follower seal has a rigid central section, and a flexible peripheral seal.
10. A vacuum-type grease gun comprising a greasing head, a barrel, a grease cartridge for fitting inside the barrel, a follower seal within the cartridge, and an end cap, the barrel being attached to the greasing head at a first end and the end cap being attachable to the barrel at a second end for closing the barrel, and the grease cartridge being long enough to protrude form the second end of the barrel when the grease cartridge is inserted into the barrel and abuts the greasing head, and short enough for the end cap to be attached to the barrel when the grease cartridge is protruding from the edge of the barrel.
11. A vacuum-type grease gun as claimed in claim 10, in which the grease cartridge is in the form of a hollow tube with two open ends.
12. A vacuum-type grease gun as claimed in claim 10 or claim 11, in which the grease cartridge is around 2mm to 6mm longer than the barrel.
13. A vacuum-type grease gun as claimed in any of claims 10 to 12, in which the grease cartridge protrudes from the second end of the barrel by substantially 3mm -5mm.
14. A vacuum-type grease gun as claimed in any of claims 10 to 13, in which the means for attaching the end cap is a screw thread on each of the end cap and the barrel.
15. A vacuum-type grease gun as claimed in claim 14, in which the extent of the screw thread is at least 10mm.
16. A vacuum-type grease gun as claimed in any of claims 10 to 15, in which an aperture is provided in the end cap.
17. A vacuum-type grease gun as claimed in claim 16, in which the aperture is provided substantially at the centre of the end cap.
18. A vacuum-type grease gun as claimed in any of claims 10 to 17, in which the follower seal has a rigid central section and a flexible peripheral seal.
19. A method of fitting a grease cartridge to a greasing head, substantially as described herein with reference to and as illustrated in Figures ito 6 of the accompanying drawings.
20. A vacuum-type grease gun substantially as described herein with reference to and as illustrated in Figures ito 6 of the accompanying drawings.