GB2506608A - Variable capacity dispensing pump - Google Patents

Abstract

A pump 1 comprising a cylinder 2, a piston 3 disposed in said cylinder 2 and moveable along a stroke axis therein in a priming direction and in a dispensing direction, a spring means 4 biasing said piston 3 to move in said priming direction, and a retention member 5 limiting movement of said piston 3 in said priming direction beyond an end point. The retention member 5 is mounted on a support member 6 and is movable thereon between a first position in which said end point determines a first cylinder capacity and at least one further position in which said end point determines a second cylinder capacity. The support member 6 my take the form of a ring having internal screw thread 44 which engages an external screw thread 46 on the retention member 5. Rotation of the support member 6 drives the retention member in either direction relative to it. The support member may be retained by clips 34, such that it can be released to allow the pump 1 to be used at maximum capacity for priming before being returned to its reduced capacity setting by re-attaching the support member 6.

Description

Pump with An Adjustable Capacity The present invention relates to a pump with an adjustable capacity, for use particularly, but not exclusively, to pump different single shot dose sizes of a chemical cleaning fluid from a dispensing device.

When chemical cleaning products are provided for use on an industrial scale, for example for cleaning hospitals or hotels, they are generally packaged in concentrated form. It is therefore necessary to mix the concentrated product with water to achieve a desired dilution ratio for use. To achieve this it is known to provide manual dispensing devices which dispense a particular dose size of concentrated product for mixing with a particular quantity of water. These generally comprise a piston and cylinder arrangement which draws a particular quantity of the concentrated product from a reservoir in a priming stroke, and then dispenses that product in a dispensing stroke. The dose size dispensed is the capacity of the cylinder.

A problem with this arrangement is that the dispensing device can be manually operated before the piston has returned to the top of the cylinder, which results in less than the intended dose size of concentrated product being dispensed.

If this occurs the resulting mixture has the incorrect dilution ratio. In order to overcome this problem it is known to provide a dispensing device with an operating plunger which is automatically disengaged from the piston after a dispensing stroke thereof, and prevented from being reengaged until the piston has performed its priming stroke and the cylinder is fully primed. As such, the dispensing device cannot be operated to dispense anything other than the intended dosage.

However, with this kind of construction the pump can only dispense this one single dose size, which is determined by the physical size of the cylinder andlor the displacement of the piston through its dispensing stroke. As stated above, this ensures that a correct dilution ratio can be achieved, but it prevents the dispensing device from being used to dispense different single dose sizes which may be required to achieve different desired dilution ratios. For example, if a new chemical product with a different concentration is to be dispensed,then the single dose size will no longer apply. Further, if it is desired to either increase or decrease the end mixture ratio for a particular cleaning purpose, this is also not possible beyond multiplications or divisions of the single dose size.

Beyond the specialist kinds of pumps described above, it may be desired to increase or decrease the cylinder capacity of any fluid dispensing pump for any reason. In applications in which non-critical products are dispensed, for example hand soap or the like, it still may be desired to be able to adjust the quantity of soap dispensed in one dispensing action, to either reduce the quantity dosed to prevent waste, or perhaps to increase it to promote better hygiene.

Before a dispensing pump can be used to dispense a product, it is necessary to fully prime the system, from the body of product in the reservoir, through an inlet line to the pump itself, and then through an outlet line and possibly a dispensing spout to an outlet. This is achieved by repeatedly driving the pump to draw fluid into the pump, and then to prime the outlet line and spout. Often this is not a particular issue, but where a pump has a small capacity and the system as a whole has a large capacity, then the pump may need to be driven many times. It is also a particular issue with single shot delay pumps like those described above, because the operator has to wait for the piston to perform its delayed priming stroke between each action.

The present invention is intended to overcome some of the above problems.

Therefore, according to the present invention, a pump comprises a cylinder, a piston disposed in said cylinder and moveable along a stroke axis therein in a priming direction and in a dispensing direction, a spring means biasing said piston to move in said priming direction, and a retention member limiting movement of said piston in said priming direction beyond an end point, in which said retention member is mounted on a support member and is movable thereon between a first position in which said end point determines a first cylinder capacity and at least one further position in which said end point determines a second cylinder capacity.

Thus, in the broadest terms the present invention provides a reciprocal pump in which the piston stroke length can be adjusted to increase or decrease the cylinder capacity, and therefore the dose size. This is achieved by adjusting the position of the retention member relative to the cylinder. As stated above, such an arrangement could find application on any kind of fluid dispensing device.

The manner in which the retention member is movably mounted on the support member can be any known arrangement, including a ratchet, a gear, a rack and pinion, a lever and so on. However, in a preferred construction the support member can comprise a first screw thread, the retention member can comprise a corresponding second screw thread engaged with said first screw thread, and the retention member can be axially movable on the support member via relative rotation between said first and second screw threads. This is a simple and expedient arrangement which allows for the retention member to be positioned at any point desired within the permissible range provided by the screw threads.

The retention member can be any physical component which can limit the movement of the piston. However, in a preferred construction the retention member can comprise an end stop surface arranged in a priming direction path of the piston, and relative rotation between the first and second screw threads can move said end stop surface back or forth on said path. Therefore, the end stop surface can physically stop the piston from moving further up the cylinder in the priming direction by blocking its path.

The support member and the retention member can be shaped in various ways to determine the location and orientation of the first and second screw threads.

For example in one possible arrangement the support member can comprise a cylindrical part which is co-axial with the cylinder but proud of the top thereof, and which has the first screw thread on an inner surface thereof. The retention member can then comprise a portion disposed inside the cylindrical part, and which has the second screw thread on an outer surface thereof. As such, rotation of this portion of the retention member inside the cylindrical pad can move it axially therein back and forth. The end stop surface can extend into the cylinder from this portion, or the piston can comprise a portion which protrudes from the cylinder and contacts the end stop surface beyond it. In another possible arrangement the support member can comprise the outer surface of the cylinder itself, and the first screw thread can be provided thereon, and the retention member can comprise a sleeve portion which overlies the cylinder, and has the second screw thread on an inner surface thereof to engage with the first screw thread. As such, rotation of the sleeve portion on the cylinder can move it axially thereon back and forth. The end stop surface can be carried by the sleeve portion and once again can either extend into the cylinder to contact the piston, or the piston can comprise a portion which protrudes from the cylinder and contacts the end stop surface beyond it.

However, in a preferred arrangement the retention member can comprise a sleeve arranged around said cylinder, and the second screw thread can be provided on an outer surface of said sleeve. The support member can then comprise a ring arranged outside the sleeve, and the first screw thread can be provided on an inner surface of said ring.

The ring could be fixed in a rotational position, and the retention member could be rotated therein to move the end stop surface back and forth. However, in a preferred construction the pump can comprise framework which holds the sleeve in a fixed rotational position, and the ring in a fixed axial position relative to the sleeve.

The sleeve can be manually rotatable to move the end stop surface back and forth on said path.

As suggested above, with the retention member comprising a sleeve arranged around the cylinder, it is possible for the retention member to be so shaped that the end stop surface extends into the cylinder. However, it is preferred to locate the end stop surface proud of the top of the cylinder. Therefore, the piston can comprise a face, and an extension portion extending from a rear side thereof and comprising an outer end. This outer end can abut against the end stop surface to limit movement of said piston in said priming direction.

This extension portion can comprise an annular wall, and the end stop surface can comprise an end stop ring disposed in a priming direction path of said annular wall. The end stop ring can be proud of a top of the cylinder and can comprise an outer edge with a greater diameter than said cylinder, and the sleeve can extend substantially normally from said outer edge.

The spring means can be a coil spring mounted inside the cylinder, or in a spring chamber co-axial therewith, in any of the known ways that piston return springs can be mounted. However, in a preferred construction the annular wall of the piston can comprise an outer end and a flange extending radially from said outer end. When the piston is at a bottom of the cylinder after a dispensing stroke thereof this flange can overlie the top of the cylinder. The spring means can then comprise a coil spring mounted around the cylinder between a static surface of the pump and an underside of the flange. This first static surface can be an area of the framework of the pump surrounding the bottom of the cylinder. Because the end stop surface prevents the movement of the piston in the cylinder beyond the end point, the coil spring can be mounted under compression between the static surface and the underside of the flange in all positions of the piston in the cylinder. Mounting the coil spring in this position, and in this state is an expedient and compact arrangement.

It will be appreciated that with the coil spring in a state of compression, the piston will be forced into engagement with the retention member, which will then transmit the spring force to the ring held by the framework. This arrangement allows for a solution to be provided to the problems associated with priming a dispensing system described above.

In particular, in a preferred embodiment the framework can comprise a resilient latch means which releasably holds the ring in the fixed axial position relative to the sleeve against an extension force transmitted thereto by the coil spring through the piston and the retention member. In a released position of the latch means the ring, the retention member and the piston can be moved to an extended position under the force applied thereto by the coil spring.

Therefore, these features allow for the cylinder capacity of the pump to be switched to its maximum in one simple movement. This can be done in order to quickly obtain the maximum pumping capacity to prime the dispensing system prior to use. It also allows for the in-use cylinder capacity previously chosen to be retained, because the ring is not moved relative to the sleeve, and when the parts are pushed back into place the ring and sleeve will return to the positions they previously occupied.

The resilient latch means can be any known construction, but in a preferred embodiment the ring can comprise a flange extending radially outwardly from an outer surface thereof, and the resilient latch means can comprise one or more resilient arms each comprising a catch at an outer end thereof which engages said flange. The pump can then comprise a release trigger moveable between a first position in which it is disengaged from the one or more resilient arms and a second position in which it forces the one or more resilient arms to flex and disengage the catches from the flange.

A plurality of these resilient arms can be provided, and they can be arranged radially around the ring. The release trigger can then comprise a cam ring supported by the framework, and comprising a cam surface of circumferentially increasing radius adjacent to each resilient arm. Rotation of the cam ring can bring a cam surface into engagement with each resilient arm, forcing it to flex outwardly.

In order to prevent the various parts from being released from the pump when the cam ring is rotated, the retention member can comprise a lug portion, and the framework can comprise an arresting member limiting movement of said lug portion beyond the extended position of the retention member.

In order to facilitate the ready return of the ring to its fixed axial position the catch of each of the resilient arms can comprise an upper tapered surface adapted to ride over the flange when the ring is moved from the extended position back to the fixed axial position thereof.

One version of the invention will now be described by way of example, and with reference to the accompanying drawings, in which: Figure 1 is an exploded view of the relevant parts of a pump according to the present invention; Figure 2 is an oblique cross-sectional side view of the relevant parts of the pump shown in Figure 1 in a first position; Figure 3 is a perspective view of the pump as shown in Figure 1 in the first position; Figure 4 is an oblique cross-sectional side view of the relevant pads of the pump as shown in Figure 1 in a second position; Figure 5 is a perspective view of the pump as shown in Figure 1 in the second position; Figure 6 is an oblique cross-sectional side view of the relevant pads of the pump as shown in Figure 1 in a third position; Figure 7 is a perspective view of the pump as shown in Figure 1 in the third position; Figure 8 is an oblique cross-sectional side view of the relevant pads of the pump as shown in Figure 1 in a fourth position; Figure 9 is a perspective view of the pump as shown in Figure 1 in the fourth position; and Figure 10 is a cross-sectional top view of the relevant parts of the pump as shown in Figure 1 in the fourth position.

Therefore, as shown in Figures 1 and 2, a pump 1 comprises a cylinder 2 and a piston 3 disposed in said cylinder 2 and moveable along a stroke axis A-A therein in a priming direction, indicated by the arrow A, and in a dispensing direction, indicated by the arrow B. It also comprises a spring means, in the form of coil spring 4, biasing said piston 3 to move in said priming direction A, and a retention member limiting movement of said piston 3 in said priming direction A beyond an end point.

The retention member 5 is mounted on a support member, in the form of ring 6, and as explained further below is movable thereon between a first position in which said end point determines a first cylinder capacity and at least one further position in which said end point determines a second cylinder capacity.

(For the sake of clarity Figures 2, 4, 6 and 8 show oblique cross-sectional side views which are at approximately 45 degrees to vertical. This angle has been chosen because it shows the resilient arms 34, as well as the first screw thread 44 and the second screw thread 46, which would not be visible in a standard cross-sectional side view because they do not extend through the vertical plane. The other parts of the pump 1 shown in these Figures are annular, so appear much as they would in a standard cross-sectional side view.) The pump 1 is part of a single dose chemical cleaning product dispensing device 7, which is best seen in Figure 3, and is configured like known devices.

(Figure 3 shows the dispensing device 7 without its internal fluid lines, nor an outer cover thereof.) Namely, the pump 1 draws fluid to be dispensed from a reservoir (not shown), and then dispenses a metered dose through an outlet 8. Referring to Figure 3, a reservoir is attached via a fluid line (not shown) which passes through aperture 9, and travels up to the pump 1 above. The fluid product is drawn into the cylinder 2 automatically in use through inlet 10 (visible in Figure 1) by negative pressure generated by movement of the piston 3 in the priming direction A, under pressure from the coil spring 4. A fluid flow restrictor (not shown) of a known kind is provided in the fluid line, or as part of the inlet 10, which restricts the rate at which the fluid product can pass through the fluid line, and therefore the rate at which the piston 3 can move in the priming direction A, under pressure from the coil spring 4. As such, an in-built delay is incorporated into the automatic priming action of the piston 3. The coil spring 4 is of such a strength that it can drive the piston 3 in the priming direction A at the maximum rate permitted by the fluid flow restrictor.

A one-way valve (not visible) is provided at the fluid inlet 10 which allows the fluid product to enter the cylinder 2. Movement of the piston 3 in the dispensing direction B under pressure from the user acting on an operating plunger 11, forces fluid product inside the cylinder 2 out of a fluid outlet 12 (visible in Figure 1). A one-way valve (not visible) is provided at the fluid outlet 12 which allows the fluid product to exit the cylinder 2. It is then sent down a second fluid line (not shown) to the outlet 8. A spout fixture or other fluid connection means can be provided at the outlet 8 to conveniently direct the fluid product for the user.

In the dispensing device 7 the operating plunger 11 is not fixed to the piston 3.

Instead, it comprises engagement means, in the form of two radially inwardly extending slots (not visible) on its interior surface, and it can be rotated on its axis between an engaged position, in which the slots are operatively connected to two radially outwardly extending tabs 13 on the piston 3, and a disengaged position, in which the slots are displaced from the tabs 13, and any axial movement of the operating plunger 11 along the stroke axis A-A is independent of the piston 3. A second coil spring 14 is mounted between the retention member 5 and the operating plunger 11, and it is placed under torsional compression when the operating plunger 11 is rotated into the engaged position, such that when the operating plunger 11 is released it is moved automatically back to the disengaged position. The second coil spring 14 also biases the operating plunger 11 back out to its stand-by position as shown in all the Figures.

With this arrangement the dispensing device 7 has a number of advantageous operational features. In particular, the operating plunger 11 can only be rotated into the engaged position once the piston 3 has completed its priming stroke. This ensures that the pump 1 can only be operated to dispense a pre-determined dose size of product equal to the set capacity of the cylinder 2. Secondly, because there is an in-built delay before piston 3 has completed its priming stroke the user must wait a moment before the pump 1 can be operated once again. This prevents users from inadvertently dispensing too much product by repeatedly depressing the operating plunger 11. In addition, because a user must rotate the operating plunger 11 to its engaged position in order to operate the pump 1, their interaction with the dispensing device 7 increases, and this helps to prevent them from misusing it. Finally, if the operating plunger 11 is depressed inadvertently in use at any time, it does not operate the pump 1 and no product is accidentally dispensed.

The manner in which the operating plunger 11 and the piston 3 interact, and the way these components are integrated into the dispensing device 7 as a whole in order to achieve the above functions is not relevant to the present invention so is not further described here in great detail.

Referring to Figures 1 and 2, the cylinder 2 is a cylindrical part which is mounted in framework 15, which is integrally formed on a backplate 16 of the dispensing device 7. The piston 3 is mounted inside the cylinder 2, and comprises a face 17, an annular side wall 18 extending therefrom and comprising an outer end 19, a flange 20 extending radially from said outer end 19 and comprising an outer edge 21, and a collar 22 extending substantially normally from said outer edge 21.

The annular side wall 18 fits snugly inside the cylinder 2, and when the piston 3 is at a bottom 23 of the cylinder 2 after a dispensing stroke thereof the flange 20 overlies a top 24 of the cylinder 2, and the collar 22 is disposed radially outwardly of the cylinder 2. The coil spring 4 is mounted around the cylinder 2, between a static surface 25, being an area of the framework 15 surrounding the bottom 23 of the cylinder 2, and the flange 20.

The retention member 5 is a tubular structure which encloses the cylinder 2 and piston 3. It comprises a sleeve 26 which is arranged around the cylinder 2, and which is held in a fixed rotational position in the framework 15. In particular, the sleeve 26 comprises a pair of radially outwardly extending lugs, one of which 27 is visible in Figure 1, which are disposed in corresponding radially inwardly extending slots, one of which 28 is visible in Figure 1, provided in the framework 15. The slots 28 have an axial extent, which allows for the retention member 5 to freely move axially back and forth as described further below, with the lugs 27 always being held in the fixed rotational position.

The sleeve 26 has openings, only one of which 29 is visible in Figure 1, on opposite sides thereof which are to allow the tabs 13 to protrude radially therethrough for the purpose of engaging the operating plunger 11. These openings 29 do not play a part in the functioning of the present invention.

The retention members also comprises an end stop ring 31, which as is clear from Figure 2 is proud of the top 24 of the cylinder 2. It is also arranged in a priming direction path of the piston 3, so it serves to prevent movement of the piston 3 in the cylinder 2 beyond the above described end point, which is its primed position in any setting. The outer end 19 of the piston 3 abuts against the end stop ring 31 in this position. The end stop ring 31 is a ring as such because the retention member 5 comprises an axially inwardly depending portion 32, which is provided for the purpose of accommodating the second coil spring 14. It addition, it will be appreciated that the coil spring 4 is held in compression when the outer end 19 of the piston 3 abuts against the end stop ring 31, 50 it is constantly held in some state of compression.

The ring 6 is a tubular structure which radially surrounds the sleeve 26 of the retention member 5. It is held in a fixed axial position in the framework 15 relative to the sleeve 26. In particular, the framework 15 comprises an annular socket 33 and four axially extending arms 34 arranged around the socket 33, which each comprise a catch 35 at an outer end 36 thereof. As is best seen in Figure 1, the ring 6 then comprises a flange 37 extending radially outwardly from an outer surface 38 thereof, and spaced from an inner end 39 thereof. The ring 6 is disposed in the socket 33, with its inner end 39 at a bottom 40 thereof, and in this position the catches 35 overlie the flange 37 and axially hold the ring 6 in the framework 15. The ring 6 rotatable in this position in the socket 33. In particular, an outer portion 41 of the ring 6 projects outwardly of the framework 15, to provide a convenient grip for manual manipulation. The outer portion 41 also comprises grip ribs 42 to make manual rotation easier.

As is also best seen in Figure 1, the inner surface 43 of the ring 6 comprises a first screw thread 44, and the outer surface 45 of the sleeve 26 comprises a second screw thread 46 adapted to co-operate with the first screw thread 44. Therefore, rotation of the ring 6 causes the retention member 5 to move axially back and forth.

This results in the end stop ring 31 moving axially back and forth on the priming direction path of the piston 3. Therefore, the above described end point, which is the primed position of the piston 3, is adjustable, which consequently adjusts the capacity of the cylinder 2 and therefore the single shot dose size of the dispensing device 7.

The first screw thread 44 and the second screw thread 46 are so sized that one 360 degree rotation of the ring 6 axially moves the end stop ring 31 back or forth by a distance which adjusts the capacity of the cylinder 2 by 5m1. The maximum capacity of the cylinder 2 is 30m1, and the minimum is 5m1, so the rotational range of the ring 6 is five 360 degree rotations.

Movement of the retention member 5 back and forth in this manner also moves the operating plunger 11 in the same way, as it is connected to the retention member 5 by the second coil spring 14. The operating plunger 11 comprises an inner portion 47 which has a radius slightly less than that of the inner surface 43 of the ring 6. This allows for the inner portion 47 of the operating plunger 11 to move into a position radially inside the ring 6 if the retention member 5 is moved axially inwardly, as shown in Figures 4 and 6. Referring back to Figures 1 and 3, an outer surface 48 of the inner portion 47 carries indicia markings 49, which relate to the set capacity of the cylinder 2. These markings 49 are positioned such that the cylinder capacity, and therefore the single shot dose size of the dispensing device 7, corresponds to the marking 49 which is aligned with an outer end 50 of the ring 6.

This construction provides a ready visual indication of the set single shot dose size.

The indicia markings 49 visible in Figures 1 and 3 are in US fluid ounces. On the opposite side of the operating plunger 11 just out of view in the Figures are a further set of indicia markings which are in millilitres. These can be seen by a user viewing the device 7 from the left side. The US fI. oz. indicia markings 49 visible are somewhat approximate because US fluid ounces do not correlate to millilitres.

However, at the maximum shot size of 30m1 the pump 1 would dispense a dose of only slightly over 1 fi. oz, so the indicia markings 49 visible do offer a useful guide for those fluent in only US fI.oz.. Although, the divisions of 3/4, 1/2 and 114 fI. oz. used do not equate to particular 360 degree rotations of the ring 6, as is the case with the ml markings on the opposite side, so that feature does not function for the US fi. oz markings 49.

With the retention member 5 in its outermost position as shown in Figures 2 and 3, the capacity of the cylinder 2 is at its maximum of 30 ml (slightly over 1 fi. oz.).

There is no fi. oz. indicia marking 49 to show this, but the markings 49 are spaced from the outer end 50 of the ring 6 such that it is clear that the cylinder capacity is about 1 fI. oz. On the opposite side of the operating plunger 5, just out of view, an indicia marking for 30m1 is aligned with the outer end 50 of the ring 6. In Figures 4 and 5 the capacity of the cylinder 2 is at an intermediate size of 15 ml. To reach this position the ring 6 has been turned through three full 360 degree rotations from the position shown in Figures 2 and 3. In this position the fi. oz. marking 49 corresponding to 1/2 fI. oz. is aligned with the outer end 50 of the ring 6, to indicate this approximate fI. oz. capacity. On the opposite side of the operating plunger 5 an indicia marking for 15 ml is aligned with the outer end 50 of the ring 6.

Correspondingly, when the capacity of the cylinder 2 is at its smallest possible size of 5m1, as shown in Figures 6 and 7, the marking 49 corresponding to 1/4 fI. oz is slightly further in than the outer end 50 of the ring 6, such that it is clear that the capacity of the cylinder is about 1/6 fI. oz. Once again, on the opposite side of the operating plunger 5, an indicia marking for 5m1 is aligned with the outer end of the ring 6. To reach this position from that shown in Figures 4 and 5 the ring 6 is turned through two further 360 degree rotations. It will be appreciated that the capacity of the cylinder 2 can be set at any position, not just those shown, and if so the indicia markings 49 provide a goad guide of the approximate single shot dose size chosen.

It will be appreciated that with the coil spring 4 in a state of compression, the piston 3 is forced into engagement with the retention member 5, which then transmits the spring force to the ring 6 through the second 46 and first 44 screw threads. This helps to keep the ring 6 and the retention member 5 engaged, but it also allows for a further function.

In particular, referring to Figure 1, a cam ring 51 is mounted in the framework around the socket 33. It comprises four cam surfaces 52 of which increase in their radius circumferentially in a clockwise direction. It also comprises an activation lever 53, which extends radially outwardly, and is disposed in an upper housing area 54 of the framework 15. In this position a cam surfaces 52 is arranged adjacent to each resilient arm 34. Referring to Figure 3, the activation lever 53 is spring loaded to a left side 55 of the upper housing area 54 by coil spring 56. In this first position each cam surfaces 52 is disposed in a clockwise position trom its corresponding resilient arm 34. The cam ring 51 can then be rotated on the socket 33 against the force of the coil spring 56, to a second position in which each cam surface 52 has been rotated in an anti-clockwise direction, which forces its corresponding resilient arm 34 to flex radially outwardly such that its catch 35 is displaced from the flange 37. This is shown in Figures 8 and 9.

It will be appreciated that when the cam ring 51 is moved into its second position the ring 6, the retention member 5 mounted therein, the operating plunger 11 mounted thereon and the piston 3 are moved to an extended position under the force applied thereto by the coil spring 4. This outward movement is arrested when the lugs 27 of the retention member 5 abut against radially inwardly extending walls 57 located at the outer ends 58 of the slots 28. Figure 10, which is a cross-sectional top view through the pump 1 which passes through the lugs 27 and the walls 57, illustrates this position.

As is clear from Figure 8, in this extended position the piston 3 is at the top 24 of the cylinder 2, in a position in which the cylinder 2 has its maximum operational capacity. Therefore, the particular design of the pump 1 allows for the capacity of the cylinder 2 to be switched to its maximum in one simple movement of the cam ring 51. This can be done with the cylinder capacity set to any position, in order to quickly obtain the maximum pumping capacity to prime the dispensing system prior to use.

It will also be appreciated that in the extended position the ring 6 and the retention member 5 are disposed in the same axial relative relationship as prior to their movement into the extended position. In Figures 8 and 9 the retention member is located such that if the ring 6 were in its fixed axial position the capacity of the cylinder 2 would be 15m1, as is shown in Figures 4 and 5. This means that when these parts are pushed back into engagement with the socket 33 and the resilient arms 34, the capacity of the cylinder 2 will return to that at which it was previously set. This allows for the full cylinder capacity to be used for priming the system without adjusting the previously set single shot dose size.

The ring 6 can be moved back into the socket 33 with the cam ring 51 held in its second position, because the catches 35 would be disposed radially outwardly of the flange 37, as shown in Figures 8 and 9. The ring 6 could then be secured in place via release of the cam ring 51 and the flexing of the resilient arms 34 back to their original position. However, it is also possible to restore the ring 6 to its fixed axial position without the cam ring 51 being held in its second position against the force of the coil spring 56. In particular, each catch 35 comprises an upper tapered surface 59 adapted to ride over the flange 37 if the ring 6 is applied to them in their original position. This forces the resilient arms 34 to flex outwardly and allow the ring 6 to pass. Once the flange 37 has passed the catches 35, the resilient arms 34 flex back to their original position, thereby fixing the ring 6 in place.

The pump 1 is operated as follows. Firstly, a reservoir of fluid to be dispensed (not shown) is attached to the inlet 10 via a fluid line (not shown) which passes through the aperture 9. Before any fluid can be dispensed the dispensing system as a whole must be primed, so the fluid fills the fluid line to the inlet 10, the cylinder 2 and the fluid line (not shown) extending from the outlet 12 of the cylinder 2 to the outlet 8 of the dispensing device 7. To achieve this the pump 1 is repeatedly manually operated. The user depresses the operating plunger 11 to drive the piston 3 in the dispensing direction B, and when the user releases the operating plunger 11 the piston 3 is driven automatically in the priming direction A under pressure from the coil spring 4. (In order to achieve this action the operating plunger 11 must first be rotated to operatively connect it to the piston 3. The manner in which this is done is not relevant to the present invention, so is not further described here.) In order to prime the dispensing system effectively, the capacity of the cylinder 2 can be set to its maximum. This can be achieved in two ways. Firstly, the ring 6 can be rotated to axially move the retention member 5 to its outermost position, as shown in Figures 2 and 3. The retention member 5 is prevented from moving any further outward from this position because the lugs 27 abut against the walls 57. In addition, the second screw thread 46 also comprises an end stop 61, which is visible in Figure 10, which prevents the first screw thread 44 and the second screw thread 46 from being rotated any further than this position. In this position the capacity of the cylinder is the maximum 30 ml.

However, if the retention member 5 is axially positioned relative to the ring 6 such that the capacity of the cylinder 2 is set at a lower dose size than 30 ml, rotating the ring 6 to move the retention member 5 outwards may require a number of manual rotational movements, and the previous positioning of the retention member is also lost. Therefore, when the retention member 5 is axially positioned relative to the ring 6 such that the capacity of the cylinder 2 is anything other than the maximum ml, it is easier to set the capacity of the cylinder 2 to its maximum by rotating the cam ring 51 to immediately release the retention member 5, the operating plunger 11 and the piston 3 to their extended positions, under the force of the coil spring 4. The activation lever 53 can be manipulated to move it in an anti-clockwise direction in the upper housing area 54, which rotates the cam ring 51 into its second position. This action brings the four cam surfaces 52 into radial engagement with the four resilient arms 34, forcing them to flex outwardly until the catches 35 have disengaged with the flange 37.

The dispensing device 1 also comprises an outer cover (not shown), which prevents users from accessing the ring 6 in normal use. A key is required to remove the outer cover to access the internal parts of the device 1. However, users can manually access the top of the activation lever 53 when the outer cover is in situ, through an opening provided therein. As such, normal users can only utilise the single action mechanism to access the maximum cylinder capacity.

To return the ring 6, the retention member 5, the operating plunger 11 and the piston 3 back to normal use positions after the dispensing system has been primed, the ring 6 is manually applied to the upper tapered surfaces 59 of the four catches 35, which then ride over the flange 37, forcing the arms 34 to flex radially outwardly to allow the flange 37 to pass. Once this has occurred the arms 34 flex radially inwardly once again so the catches 35 overlie the flange 37 and secure the ring 6 back in its fixed axial position around the socket 33. A user can achieve this while the outer cover is in situ, as they only need to depress the operating plunger 11 against the force of the second coil spring 14 until it contacts the retention member 5, and then continue to depress the operating plunger 11 to apply the ring 6 to the arms 34.

Once the dispensing system has been primed, the pump 1 can be used to dispense the fluid from the dispensing device 7. As explained above, the pump 1 is a single shot pump designed to dispense doses of a pre-determined amount of fluid. It comprises a number of features which are not relevant to the present invention which ensure that the user can only dispense this pre-determined amount, and can only do so after a delay interval after the previous dispensing action. However, to set the dose size required the ring 6 is rotated to move the retention member 5 axially back and forth, until the indicia marking 49 corresponding to the dose size required is aligned with the outer end 50 of the ring 6. Rotation of the ring 6 rotates the first screw thread 44, which drives the second screw thread 46 to move the sleeve 26 axially back and forth. Consequently the end stop ring 31 is moved axially back and forth along the priming direction path of the outer end 19 of the piston 3, which moves the face 17 of the piston 2 up and down inside the cylinder 2, against the force of the coil spring 4, thereby to adjust the capacity of the cylinder 2.

Figures 2 and 3 show the retention member 5 in an outermost axial position in relation to the ring 6, in which the capacity of the cylinder 2 is at its maximum of 30 ml. In Figures 4 and 5 the ring 6 has been turned through three 360 rotations to move the retention member 5 to a mid axial position relative thereto, in which the capacity of the cylinder 2 is at 15 ml. In Figures 6 and 7 the ring 6 has been turned through two further 360 rotations to move the retention member 5 to an innermost axial position in relation to the ring 6, in which the capacity of the cylinder 2 is at its minimum of 5 ml. In this position the first screw thread 44 is located at the outermost point of the second screw thread 46, so no further axial movement is possible. An end stop wall (not visible) is provided on the second screw thread 46 which prevents further rotation. In addition, an inner end 60 of the sleeve 26 abuts against the backplate 16 in this position in any case. It will be appreciated that the ring 6 can be rotated to move the retention member 5 such that the capacity of the cylinder 2 is set at any point between the maximum and the minimum, as desired.

Therefore, with the capacity of the cylinder 2 set in this way, every time the operating plunger 11 is driven to dispense a dose of fluid, an amount equal to the set capacity of the cylinder 2 will be dispensed. When the reservoir of fluid product is spent, another can be attached to the pump 1 to replace it. If the dispensing system requires priming after this, then the cam ring 51 can be rotated to release the ring 6 and the associated parts to their extended position to make the full cylinder capacity available. When the ring 6 is then placed back into its fixed axial position the previously set capacity of the cylinder 2 will once again be applied.

The present invention can be altered without departing from the scope of claim 1. In particular, in alternative embodiments (not shown) the retention member part is movably mounted on the support member part using a ratchet, a gear, a rack and pinion and a lever.

In a further alternative embodiment (not shown) the support member part comprises a cylindrical component which is co-axial with the cylinder but proud of the top thereof, and which has the first screw thread on an inner surface thereof. The retention member part then comprises a portion disposed inside the cylindrical component, and which has the second screw thread on an outer surface thereof. As such, rotation of this portion of the retention member inside the cylindrical component moves it axially therein back and forth.

In another alternative embodiment (not shown) the support member part comprises the outer surface of the cylinder itself, and the first screw thread is provided thereon, and the retention member part comprises a sleeve portion which overlies the cylinder, and has the second screw thread on an inner surface thereof to engage with the first screw thread. As such, rotation of the sleeve portion on the cylinder moves it axially thereon back and forth.

In another alternative embodiment (not shown) the ring is mounted in the framework in a fixed rotational position, and the retention member is rotated thereon to move the end stop surface back and forth.

Therefore, the present invention provides a reciprocal pump in which the piston stroke length can be adjusted to increase or decrease the cylinder capacity, and therefore the single action dose size. This allows for a single product to be provided which can be used to dispense different dose sizes as required. This prevents the need to manufacture and supply pumps of different integral capacities.

It also allows users to readily change to a different dose size to change the dilution ratio of the mixture produced, which may be useful if the mixture proves to be too weak or too strong in use, or if the user wants to use a different chemical product which requires a different dilution ratio. The present invention also provides a pump in which the capacity of the cylinder can be increased to a larger size in a single action, in order to make priming a dispensing system easier.

Claims (14)

1. Claims 1. A pump comprising a cylinder, a piston disposed in said cylinder and moveable along a stroke axis therein in a priming direction and in a dispensing direction, a spring means biasing said piston to move in said priming direction, and a retention member limiting movement of said piston in said priming direction beyond an end point, in which said retention member is mounted on a support member and is movable thereon between a first position in which said end point determines a first cylinder capacity and at least one further position in which said end point determines a second cylinder capacity.
2. 2. A pump as claimed in claim 1 in which said support member comprises a first screw thread, in which said retention member comprises a corresponding second screw thread engaged with said first screw thread, and in which said retention member is axially movable on the support member via relative rotation between said first and second screw threads.
3. 3. A pump as claimed in claim 2 in which said retention member comprises an end stop surface arranged in a priming direction path of said piston, and in which relative rotation between said first and second screw threads moves said end stop surface back or forth on said path.
4. 4. A pump as claimed in claim 3 in which said retention member comprises a sleeve arranged around said cylinder, in which said second screw thread is provided on an outer surface of said sleeve, in which said support member comprises a ring arranged outside said sleeve, and in which said first screw thread is provided on an inner surface of said ring.
5. 5. A pump as claimed in claim 4 in which said pump comprises framework which holds said sleeve in a fixed rotational position, in which said framework holds said ring in a fixed axial position relative to said sleeve, and in which said sleeve is manually rotatable to move said end stop surface back and forth on said path.
6. 6. A pump as claimed in claim 5 in which said piston comprises a face, an extension portion extending from a rear side thereof and comprising an outer end, and in which said outer end abuts against said end stop surface to limit movement of said piston in said priming direction.
7. 7. A pump as claimed in claim 6 in which said extension portion comprises an annular wall, in which said end stop surface comprises an end stop ring disposed in a priming direction path of said annular wall, in which said end stop ring is proud of a top of said cylinder and comprises an outer edge with a greater diameter than said cylinder, and in which said sleeve extends substantially normally from said outer edge.
8. 8. A pump as claimed in claim 7 in which said annular wall comprises an outer end and a flange extending radially from said outer end, in which when said piston is at a bottom of said cylinder after a dispensing stroke thereof said flange overlies the top of said cylinder, and in which said spring means comprises a coil spring mounted around said cylinder between a static surface of said pump and an underside of said flange.
9. 9. A pump as claimed in claim 8 in which said framework comprises a resilient latch means which releasably holds said ring in said fixed axial position relative to said sleeve against an extension force transmitted thereto by the coil spring through said piston and said retention member, and in which in a released position of said latch means said ring, said retention member and said piston are moved to an extended position under the force applied thereto by said coil spring.
10. 10. A pump as claimed in claim 9 in which said ring comprises a flange extending radially outwardly from an outer surface thereof, in which said resilient latch means comprises one or more resilient arms each comprising a catch at an outer end thereof which engages said flange, in which said pump comprises a release trigger moveable between a first position in which it is disengaged from said one or more resilient arms and a second position in which it forces said one or more resilient arms to flex and disengage said catches from said flange.
11. 11. A pump as claimed in claim 10 in which a plurality of resilient arms are provided, which are arranged radially around said ring, in which said release trigger comprises a cam ring supported by said framework, and comprising a cam surface of circurnferentially increasing radius adjacent to each resilient arm, and in which rotation of said cam ring brings a cam surface into engagement with each resilient arm, forcing it to flex outwardly.
12. 12. A pump as claimed in claim 11 in which said retention member comprises a lug portion, in which said framework comprises an arresting member limiting movement of said lug portion beyond said extended position of said retention member.
13. 13. A pump as claimed in claim 12 in which said catch of each of said resilient arms comprises an upper tapered surface adapted to ride over said flange when said ring is moved from said extended position back to said fixed axial position thereof.
14. 14. A pump substantially as described herein and as shown in the accompanying drawings.