Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
TRIGGER AEROSOL CAN REPLACEMENT
Document Type and Number:
WIPO Patent Application WO/2017/001810
Kind Code:
A1
Abstract:
A manually operated pump dispenser that is activated by a trigger handle (133) for dispensing a fluid from a non-pressurized container (101) as an atomised spray or foam wherein as the trigger handle (133) is moved from a first to a second position it moves a pump plunger (113) from a downstream position to an upstream position drawing fluid into the pump chamber (110) from the container (101) through a valve (109) and simultaneously causing a resiliently deformable part (117) to be tensioned and wherein as the trigger handle (133) returns from the second position to the first position under the action of the resiliently deformable part (117) reforming the plunger (113) also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber (110) and through a final orifice (129).

Inventors:
LAIDLER, Keith (35 Fairfield Rise, Wollaston Stourbridg, West Midlands DY8 3PQ, GB)
Application Number:
GB2016/000132
Publication Date:
January 05, 2017
Filing Date:
June 28, 2016
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
LEAFGREEN LIMITED (35 Fairfield Rise, Wollaston Stourbridge, West Midlands DY8 3PQ, GB)
International Classes:
B05B9/08; B05B1/12; B05B11/00
Domestic Patent References:
2006-12-28
Foreign References:
JPH09301410A1997-11-25
EP1449594A12004-08-25
FR1147172A1957-11-20
Other References:
None
Attorney, Agent or Firm:
LAIDLER, Keith (Leafgreen Limited, 35 Fairfield RiseWollaston, Stourbridge, West Midlands DY8 3PQ, GB)
Download PDF:
Claims:
Claims

1. A manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice

2. A device as described in the previous claim wherein there is a separate second handle, lever, button or equivalent that has to be moved to enable the fluid to discharge.

3. A device as described in any of the previous claims wherein the second handle, lever, button or equivalent is spring loaded so that once released it goes back to its original position closing off the discharge of fluid from the outlet orifice.

4. A device as described in the previous claims wherein the second handle, lever, button or equivalent opens and closes an outlet valve.

5. A device as described in claims 1 - 3 wherein the second handle, lever, button or equivalent enables a valve to open and close.

6. A device as described in claims 1 - 3 wherein the second handle, lever, button or equivalent opens and closes a fluidic outlet route.

7. A device as described in claims 1 - 3 wherein the second handle, lever, button or equivalent when activated moves the final spray orifice and an outlet valve to enable the fluid to discharge.

8. . A device as described in any of the previous claims wherein the second handle, lever, button or equivalent is positioned so that a finger or thumb of the same hand used on the trigger handle can activate it.

9. . A device as described in any of the previous claims wherein the second handle, lever, button or equivalent is positioned above, on or around the trigger handle in such a way that a finger or thumb of the same hand used on the trigger handle can activate it

10. A device as described in any of the previous claims wherein the second handle, lever, button or equivalent is pivoted and the finger contacts it to activate it.

11. A device as described in the previous claims wherein the resiliently deformable part is a spring.

12. A device as described in the previous claims wherein the resiliently deformable part is pretensioned to generate a minimum pressure for the fluid when it is discharged.

13. A device as described in the previous claims wherein the maximum fluid pressure in the pump chamber is determined by the distance of the inward movement of the trigger, the strength of the resiliently deformable element and the size of the pump chamber.

14. A device as described in the previous claims wherein the maximum possible fluid volume and pressure in the pump chamber is achieved after one full inward movement of the trigger handle from the first to the second position.

15. A device as described in the previous claims wherein the minimum discharge time from one full movement of the handle from the second to the first position is over 0.1 seconds.

16. A device as described in the previous claims wherein the maximum discharge time from one full movement of the handle from the second to the first position is under 10 seconds

17. A device as described in the previous claims wherein the discharge is continuous lasting under 10 seconds from one full movement of the handle from the second to the first position.

18. A device as described in any of the previous claims wherein the outlet from the pump chamber is followed by a swirl and a finial orifice to create a spray.

19. A device as described in any of the claims 1 - 17 wherein the outlet from the pump chamber is followed by a swirl and a finial orifice and a tube to create a foam.

20. A device as described in any of the claims 1 - 17 wherein the outlet from the pump chamber is followed by one or more meshes to create a foam.

21. A device as described in any of the previous claims wherein the fluid is a liquor.

22. A device as described in any of the previous claims wherein the fluid is a liquor and air or gas.

Description:
Trigger Aerosol Can Replacement

The present invention relates to a more efficient manually actuated pump type fluid dispenser that produces a discharge as the trigger handle returns rather than as the user pulls it inwards enabling large volumes to be discharged. In a preferred version it is also only activated by actuating a button or lever that acts as an on / off switch so it competes with pressurized gas aerosol dispensers but uses none pressurized containers.

Many products are dispensed with pressurized gas aerosols commonly known as aerosols. Most of these use metal cans and propellents such as butane but companies are starting to switch over to using compressed air aerosols and these are now also made with plastic containers. People like aerosols because they are so user friendly and convenient and the butane aerosols produce an excellent performance with sprays and foams. Compressed air aerosols are as easy to use but the pressures have to be much higher typically starting at around 10 bars and ending up around 3 bars and the performance isn't as consistent or good and the containers have to be stronger. They are much more environmentally friendly though.

Manually actuated pump type fluid dispensers are commonly used to provide a means by which fluids can be dispensed from a none pressurised container. Typically, dispensers of this kind have a pump arrangement which is located above the container when in use. The pump includes a pump chamber connected with the container by means of an inlet having an inlet valve and with a dispensing outlet via an outlet valve. To actuate the dispenser, a user manually applies a force to an actuator to reduce the volume of the pump chamber and pressurise the fluid inside and to compress a spring. Once the pressure in the chamber reaches a pre-determined value, the outlet valve opens and the fluid is expelled through the outlet. When the user removes the actuating force, the spring reforms and the volume of the chamber increases and the pressure in the chamber falls. This closes the outlet valve and draws a further charge of fluid up into the chamber through the inlet. A range of fluids can be dispensed this way this way including pastes, gels, liquid foams and liquids. In certain applications, the fluid is dispensed in the form of an atomised spray, in which case the outlet will comprise an atomising nozzle. The actuator may be push button or cap, though in some applications the actuator arrangement includes a trigger that can be pulled by a user's fingers.

A large number of commercial products are presented to consumers in a manual pump type dispenser, including, for example, tooth paste, antiperspirant, de-odorant, perfumes, air fresheners, antiseptics, paints, insecticides, polish, hair care products, pharmaceuticals, shaving gels and foams, water and lubricants.

There are numerous types of manually activated pumps and triggers on the market and they are sold in enormous volumes especially through the major retailers such as supermarkets. One of the biggest drawbacks with pumps and triggers is the fact that they deliver pulses of fluid rather than a continuous discharge. Generally they deliver a disc shaped spray or foam or a bolus of fluid. So, if someone sprays onto a wall or onto furniture they produce a series of discs with some overlapping in parts and gaps between them. Similarly, if you spray into the air with an air treatment such as air freshener, you don't achieve an even coverage when you spray. A better alternative is to deliver a continuous spray or foam so that a much more even coverage is attained. There are continuous pumps and triggers on the market that use special containers where the user pumps air into the canister and continues to do so until a sufficient pressure has been reached and the fluid is then driven out by the compressed air. The user then simply presses on an actuator which acts as an on / off switch just like with an aerosol until the pressure drops by too much when the container has to be repressurised. These work well and can be reused but they tend to be too costly and bulky and are much less user friendly than aerosols. It is also difficult to achieve the same high pressures that are possible with aerosols so the performance isn't as good.

Our first innovation is to make a trigger actuated pump that is almost as simple to use as an aerosol and is cheaper, fully controllable with an on / off switch, uses a none pressurized container, can work at higher pressures, is reusable and most importantly, only normally needs one simple pull of the trigger each time it is used. The main limitation of the device being that it can practically only deliver a maximum of 3 - 5 mis of fluid from each pull of the trigger and this makes it unsuitable for many aerosol applications as many deliver 6 mis plus each time they are used. Of course, this could be used in such applications by simply pulling the trigger a second time and that would be acceptable for some of those applications but ceases to be as convenient as an aerosol and it doesn't discharge as the trigger is pulled inwards. Another limitation would be for very small aerosols where the trigger version would be more expensive and bulkier. The device isn't intended to replace all aerosols or triggers and merely some of them.

Our second innovation uses the same device with a larger outlet orifice to deliver a substantial pulse of fluid. In practice most trigger dispensers used in the mass volume markets such as those sold in supermarkets are limited to dispensing 1.5 mis per stroke because of the actuation force required. Yet there is a market for such devices delivering higher discharges of over 2 mis and up to as high as 4 mis as a single pulse discharged over around 0.25 seconds as normal. This is because the user has to make fewer actuations and tends to use more liquor which leads to more sales for the supplier. The higher efficiency of this innovation makes large discharges practical and it can be done with or without the second lever or button but for cost, simplicity and ease of manufacturing in most cases it would be made without However, such devices usually have some sort of lock to prevent the user operating it accidentally so the button or lever could double up as a lock or could be modified so it functions solely as a lock. The action is less natural than with a standard trigger sprayer as the fluid is discharged as the handle returns on the pump return stroke rather than as the handle is pulled inwards on the pump compression stroke. But it is important as the forces have to be minimized for this to work with such high discharges. The time of the discharge could easily be increased if required simply by reducing the size of the final orifice.

According to a first aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice According to a second aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part refoiming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice provided that a second separate handle, lever, button or equivalent is also moved.

According to a third aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice provided that a second separate handle, lever, button or equivalent is also moved and the second handle, lever, button or equivalent is positioned above, on or around the trigger handle in such a way that the index finger of the same hand on the trigger handle can activate it.

According to a fourth aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice provided that a second separate handle, lever, button or equivalent is also moved.

According to a fifth aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice provided that a second separate handle, lever, button or equivalent is also moved wherein the discharge is then continuous lasting under 10 seconds from one full movement of the trigger handle.

According to a sixth aspect of the present invention there is provided a manually operated pump dispenser that is activated by a trigger handle for dispensing a fluid from a none pressurized container as an atomised spray or foam wherein as the trigger handle is moved from a first to a second position it moves a pump plunger from a downstream position to an upstream position drawing fluid into the pump chamber from a container through a valve and simultaneously causing a resiliently deformable part to be tensioned and wherein as the trigger handle returns from the second position to the first position under the action of the resiliently deformable part reforming the plunger also returns from the upstream position to the downstream position and fluid is discharged from the pump chamber and through the final orifice wherein the maximum possible fluid volume and pressure in the pump chamber is achieved after one full inward movement of the trigger handle from the first to the second position.

An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawing, in which:

Figure 1 is a cross-sectional view of a dispenser pump actuated with a trigger handle and a smaller second trigger in the none pressurized condition configured in accordance with the invention;

Figure 2 is a cross-sectional view of figure 1 in the pressurized condition;

Figure 3 is a view of the device in figures 1 and 2 on a shaped container; Figure 4 is a cross-sectional view of a dispenser pump actuated with a trigger handle and a smaller second button in the none pressurized condition configured in accordance with the invention;

Figure 5 is a cross-sectional view of figure 4 in the pressurized condition;

Figure 6 is a view of the device in figures 4 and 5 on a shaped container;

Figures 1, 2 and 3 show a first embodiment of a manually actuated pump dispenser with a trigger in accordance with the invention. The arrangement itself comprises the following component parts, a none pressurised container 101 with a cap fitting 103 which could be a thread, snap fit or bayonet fitting or any other suitable arrangement. A cap 100 has a annular ledge 102 that goes onto the container and is fixed with a matching arrangement on the container as at 103. It also has an inlet tube 106 which retains a diptube 104 that goes to the base of the container 101 so fluid can be sucked up from the container 101 through the diptube inlet 105. The cap part 102 has an inlet 108 to the pump chamber 110 and there is an inlet to the ball valve 109 which is restrained from moving too far from the inlet hole 108 by a small annular ledge 112. The pump chamber 110 has a plunger 113 with 2 annular seals 114 and 115 that seal against the pump chamber wall 116. There is a rod 119 attached to the centre of the plunger 113 that has an end stopper 121. The pump chamber 110 has an upstream end wall 118 with a hole 120 in it that the plunger rod 119 passes through and a spring 117 is sited between the end wall 118 and plunger 113 and around the plunger rod 119. There is an outlet 111 from the pump chamber 110 that leads to an outlet hole 122 and into a small tubular chamber 127. An outlet valve 123 seals the outlet hole 122 with a conically tapered prodder 124 and it also seals the small chamber 127 with an annular seal 126 The outlet valve 123 is also fixed inside a tube that has an outlet orifice 129 and is part of a small handle or lever 131 which pivots around a pivot point 132 against a resiliently deformable lever 140 and acts as a spring for the small handle 131. The outlet valve 123 combines with the orifice part of the cap 131 to form a swirl 130 so the liquor leaves the orifice 129 as an atomised spray. There is a trigger handle 133 that pivots at 134 and has a lever 135 that engages with the plunger rod 119 and the rod end 121 which is inside the slot 136 in the lever 135 moving it upstream as the handle is pulled inwards by the user.

As the trigger 133 is pulled inwards by the user, the plunger 113 is moved upstream by the action of the trigger lever 135 moving the plunger rod end 121 inside the slot 136 adding tension to the spring 117 by compressing it and drawing liquor up from the container 101 through the diptube 104 past the ball inlet valve 109 and into the pump chamber 110. The trigger 133 is normally pulled as far inwards as possible and the plunger 113 moves the corresponding distance upstream. Figure 1 shows the initial position and figure 2 shows the maximum position with the lever 131 pulled in, the valve 124 in the unsealed position and fluid able to be discharged from the spray orifice 129. When the trigger 133 is released the spring 117 acts upon the plunger 113 which in turn pressurises the fluid in the pump chamber 110 and the tube 111. The fluid is trapped by the ball inlet valve 109 and the outlet valve prodder 124. The user can open the outlet valve 123 by moving his index finger from the trigger 133 to pull on the lever 131. This rotates around the pivot point 132 causing the orifice part of the lever to draw the outlet valve 123 away from the outlet hole 122 allowing liquor into the small chamber 127. The liquor can only escape through a hole 137 in the outlet valve 123 because of the annular seal 126 and it then goes to the swirl chamber 130 and then through the final orifice 129. If the user releases the lever 131 then the spring element 140 on the lever 131 pushes the lever 131 back to its rest position and also the outlet valve 123 back in position so the prodder 124 seals the outlet 122. As the liquor is discharged the trigger 133 gradually moves back outwards. Once the discharge is stopped then the trigger 133 remains in its latest position. The user can pull the trigger 133 back at any time so the pump chamber 110 refills to its maximum but if that is done while the device is discharging it will immediately stop discharging because the liquor is no longer pressurized and the liquor will instead be drawn into the expanding pump chamberl 10 through the diptube 104.

The inlet valve is shown as a ball 109 and its movement is restricted by an annular ledge 112. This is so the ball 109 can move away from the inlet hole 108 to allow liquor to pass when required and it stops the ball 109 from moving too far away so that when the device is discharging the ball 109 is pushed against the inlet hole 108 by the liquor pressure even if the device is inverted. Any suitable one way inlet valve could be used and there are many examples used in conventional triggers and pumps and aerosols. This is simply one example. Similarly, the lever 131 could activate any type of outlet valve and this is just one example.

In figures 4, 5 and 6 we see another example of the device according to the invention where there is a main trigger handle 133 that is pulled in to pressurize the pump chamber 110 and this time there is a second moveable valve 403 that has to be opened by pushing a finger onto the top button 401 of the cap 100 for the fluid to discharge. This device works substantially the same as the previous example but is used much more like a standard aerosol and the user picks up the device and simultaneously pulls in the trigger handle 133 to pressurize the pump chamber 110. The trigger handle 133 is then released and the fingers grip the container as they would an aerosol can. One or more digits of the same hand and usually the index finger then pushes on the button 401 at the top of the cap and this pushes a valve 403 down inside a tube opening a flow route for the fluid from the pump chamber 110 to the one way ball valve 411 which moves so the fluid is dispensed through the final orifice 129. The valve 403 has 3 seals with the top seal 405 preventing the fluid from escaping around the valve 403, the bottom seal 407 prevents the fluid from filling up the chamber around the spring part 406 of the valve 403 and the central seal 408 in the off position seals the outlet route from the pump chamber 110 to the ball valve 411 as shown in figure 4. In figure 5 the seal 408 has been moved down by the button 401 pressing on the valve 403 and no longer seals the outlet route.

As the fluid is dispensed past the one way ball valve 411, through the chamber 412, through the channel 413 and through the spray swirl 414 and spray orifice 129 so the volume of fluid in the pump chamber 110 reduces, the pump plunger 113 moves down and the trigger handle 113 moves out. If the user releases the button 401 then the valve 403 and button 401 return to their original positions under the action of the resiliently deformable part 406 of the valve and the action of the resiliently deformable hinge 402 of the button 401 shutting off the fluid route, stopping any discharge and halting the movement of the trigger handle 133. If the user then presses again on the button 401, the process resumes until it is released or all of the fluid in the pump chamber 110 is dispensed and the trigger handle 133 has returned to the start position. The user would normally only need to pull the trigger handle 133 in once but could do so several times with no discharge during the pulls for a prolonged discharge and could pull it in fully or partially from any position between the start position and the position of maximum travel. The button 401 could be kept depressed as the one way ball valve 411 near to the final orifice 129 prevents air being sucked back into the pump chamber 110 but the user would normally release the button 401 when the trigger handle 133 is being pulled as no fluid can be discharged because there is no pressure in the pump chamber 110. There are many ways of opening and closing the fluidic path from the pump chamber 110 to the final orifice 129 and this is simply one example. Any suitable valve or button could be used.

Throughout the trigger handle 133 is described as being pulled in because this is the most natural action but it could be configured so it is pushed, moved in some way or squeezed instead.

One of the keys to the success of this device is pulling the trigger in and not discharging simultaneously or pressurizing the liquor and then having the trigger return to its original position relatively slowly. Conventional triggers use the inward movement of the trigger to drive the plunger against the liquor forcing it through an orifice at pressure and the spring then forces the trigger back to its original position as quickly as possible. These twin actions cause the user to expend a lot of effort whereas our version only needs enough effort to tension the spring to then pressurise the fluid when released and that is far less. Consequently we are able to either store more liquor in the pump chamber and or create a greater high and low pressure on the liquor. We can also set the minimum pressure of the liquor by pretensioning the spring so when the pump chamber is almost empty, there is still a minimum required pressure. This would usually be 4 - 5 bars or higher for high pressure applications with lower discharge rates but could be as low as 1 - 4 bars. When the device is used for a fast discharge the discharge would normally be high and over 1.5 mis and preferably over 2 mis and up to 5 mis. The second handle, lever or button or equivalent could still be used so that it is activated at the same time as the main trigger handle is drawn inwards or the device could be made without the second handle, lever or button. It actually has limited value with this configuration and it may be cheaper simply not to use it or it could act as a lock.

The penalty of this design over a standard aerosol is that the volume of liquor that can be stored at any time is very limited because the distance that the trigger can be moved is restricted by the size of a user with a small hand and the force that can be produced is similarly restricted. Also, the higher the pressure of the liquor which is determined primarily by the amount the spring is pretensioned, the lower the volume that can be used because of the actuation force restriction. So for continuous discharge the device is aimed at applications where the discharge volume is under 6 mis and preferably under 4 mis and where the flow rate is around 0.8 mis / sec or under as this gives a spray or discharge time of around 5 seconds or more. Ideally you want a discharge time of around 6 seconds or more and a rninimum pressure of at least 4 bars. Any less and you are usually better served with using a standard aerosol or trigger but the applications aren't restricted to being used for those discharges or times.

A possible problem with such a design is that the device could produce an unacceptably high pressure and that is why it is designed to be used after one pull of the trigger and the pump chamber is sized so that at the maximum inward movement of the trigger the pressure is less than a preset value which would normally be less than 12 bars and often under 10 bars. Once the trigger handle has been moved fully inwards it cannot be moved outwards until the second button, lever or handle is moved because the fluid can't be discharged and the plunger cannot move. If part of the chamber is discharged and the handle is moved back inwards then all that happens is the chamber refills. The highest pressure is almost as important as the lowest pressure as minimizing the pressure range helps to maintain a more consistent discharge quality especially with spray droplets.

For this to be as user friendly as a standard aerosol canister we want an on / off switch that is easy to use with the same hand that operates the trigger. That is why we developed the lever or button that the index finger can operate. The lever or button could be designed in other ways and what is important is that there is some kind of lever, flap, mini trigger or button that can be depressed by a finger or thumb of the same hand in a comfortable and simple way. It has to be spring loaded so when released it shuts off the liquor flow to the orifice. This arrangement is so good that it can be used with any type of continuous spray trigger device for producing a foam or atomised spray and the concept may be split off as a separate patent application.

The outlet orifice shown is configured to produce an atomised spray but it could just as easily be configured to produce a bolus of liquor or a foam and these would be done in similar ways to those already used with trigger actuated dispensers or aerosols. Foams tend to be produced by following the swirl and outlet orifice with a mesh or a tube where the foam is produced inside the tube. Similarly, the device could be configured to discharge more than one liquor or a liquor and air or a liquor and gas and again this would be done in similar ways to those already used with trigger actuated dispensers or aerosols. The pump chamber could be configured so it draws in air as well as liquor and this could be done in a number of different ways that are well known including using a small air hole near to the top of the diptube.

Whereas the invention has been described in relation to what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not limited to the disclosed arrangements but rather is intended to cover various modifications and equivalent constructions included within the spirit and scope of the invention.