GB2462820A

GB2462820A - Pressure operated metering pump

Info

Publication number: GB2462820A
Application number: GB0815091A
Authority: GB
Inventors: Terence Edward Weston
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-08-19
Filing date: 2008-08-19
Publication date: 2010-02-24
Also published as: GB0815091D0

Abstract

A dispenser comprises a flexible container 2 containing a fluid product 3. A pump 4 is attached to the container 2 by a screw cap 5, sealing means being provided by a resilient gasket 7 between the pump 4 and the shoulder 6 of container 2. Pump 4 comprises a cylinder 25, piston 8 and spring 9, and interposed between the bore of the cylinder and the outside of the piston is a freely sliding sleeve 14. By selecting the clearances between the sliding surfaces, which may vary for different viscosities of product, the longitudinal movement of the sleeve of the sleeve 14 with respect to the piston 8 will always lag when the piston moves. Dispensing is performed by squeezing the container which exerts a pressure P on the piston. An outlet nozzle 10 houses a duckbill non-return valve and a frangible seal maintains integrity of the product until first opened.

Description

BACKGROUND TO THE INVENTION

There are many applications of fluid dispensing from a container where a metered dose is required. Trigger pumps and palm pumps are two examples of manually operated pumps in very common use, which dispense a measured volume of fluid by the action of moving a piston within a cylinder a fixed distance, thereby to discharge the fluid through a nozzle. Non-return valves are used to control the direction of flow of fluid, and the piston pumps normally employ a compression spring to return the piston.

A non-metering type of pump increasingly popular is a squeezable container which is stored and used with the outlet nozzle facing down. These are convenient to use and inexpensive to manufacture. The outlet nozzle is generally fitted with a valve having a high cracking pressure in the dispensing mode, and free flow to allow air to enter the container to replace the volume of fluid dispensed. A typical valve used in squeeze bottles is known as a dome valve, constructed usually of a flexible elastomer, and having a slit through a thin domed membrane. Application of pressure to the convex face causes an initial increase to flow, but above a predetermined pressure, the valve suddenly reverses its form and the slit opens, permitting fluid flow therethro ugh. On removal of the squeezing force, the flexible container returns to its original form, thus creating a lower pressure within. This causes the dome valve to return to its original shape, and the partial vacuum within the container causes the air pressure outside the container to open the slit in the valve and air bubbles back through the fluid until the internal and external pressures are approximately equal. The dome valve further prevents the leakage of fluid when the container is stored nozzle down.

There is a demand for the convenience and simplicity of the squeezable bottle type dispenser combined with portion dispensing, particularly for products such as herbicides, pesticides and other horticultural products, for foods such as sauces, and domestic chemicals such as dish-washer rinse aides. The prior art provides squeezable containers wherein a chamber at the top of the squeezable container is fed with a dip tub connected to the contents of the container until the required volume is transferred, and then the contents of the chamber are discharged by tipping the complete container. Typical prior art is described in US 2006 0108377.

These devices are inconvenient for many products such as sauces, lotions, medicaments, and the like, and the previously mentioned trigger pumps are not usually ergonomically suited to such applications. For metering applications it is undesirable for the replenishment air to bubble back through the product, which would affect the accuracy of portion if air became entrapped. Furthermore, for some applications it is desirable to prevent contamination of the fluid product by the air drawn into the container after each operation, but the prior art dispensers do not provide means for separating the product from the air.

DESCRIPTION OF THE INVENTION

The present invention seeks to provide a squeezable container combined with a pressure operated metering pump, suitable for storing and operating in the nozzle down orientation.

In a first embodiment, a squeezable container has a pump which is operated by the increase in pressure within the container when it is squeezed. The pump has a spring returned piston of fixed stroke, and the container is fitted with an air admittance valve to allow air to enter the container to replace the volume of product dispensed. The outlet nozzle is fitted with a so-called duckbill valve which permits free flow in the dispensing mode, and zero flow during recharging the pump.

In a second embodiment, which has a pressure operated pump as described, the product is contained within a bag, sealed to the atmosphere, and in fluid connection with the pump. A squeezable outer container for the bag is squeezed by the user, which causes a pressure increase therein, which simultaneously pressurizes the bag of product. The pump operates in response to the pressure increase to dispense the metered dose of product. As in the first embodiment, an air admittance valve allows the outer container to return to its original volume, but the bag containing the product progressively collapses as the product is sequentially dispensed. Thus the product is protected from air-borne contamination.

The present specification describes a cartridge type of pump for attaching to the container or bag with a screw cap, but the pump may be manufactured as an integral part of the cap or container.

The pressure generated by squeezing a typical container may be a low as 0.056 kgtlcm2 (8 lbf/in2), and the force available to operate the pump is much lower than that available with trigger pumps. Therefore the described embodiments minimise frictional losses and rely on the viscosity of the product to provide a seal between the piston and cylinder. Of course, in certain sizes and configurations, a piston seal is viable, and the present description should be read as including such a seal.

The invention is now described with reference to the following drawings.

Figure 1 is a centre-line section through the general arrangement of the first embodiment, and figure la shows an alternative discharge valve of the dome type.

Figure 2 is a longitudinal centre-line section through the metering pump, and figure 3 is scrap section at right angles to the longitudinal axis at section lines X-x.

Figures 4,5,6 and 7 show the operating sequence of the pump.

Figure 8 shows the second embodiment comprising the metering pump and bag-in-container.

Similar components and details are given similar annotation.

Referring to figure 1, the dispensing pack 1 comprises a flexible container 2 containing a fluid product 3. A pump 4 is attached to the container 2 by the screw cap 5, sealing means provided by the resilient gasket 7 between the pump 4 and the shoulder 6 of container 2. Pump 4 comprises a cylinder 25 and piston 8.

Interposed between the bore of the cylinder 25 and the outside of the piston 8 is a freely sliding sleeve 14. The piston 8 is hollow, and within the cavity 17 is located a compression spring 9 which acts on the end wall 18 of the piston 8 and the inner face 23 of the cylinder 25 to urge the piston 8 towards the container 2. In the position shown, the outer face of the piston 8 contacts the resilient gasket 7 to seal the product 3 within the container 2. An outlet nozzle 10 houses a duckbill non-return valve, and a frangible seal 12 maintains the integrity of the product until first opened, and provides tamper evidence. (this feature is omitted in subsequent drawings). Valve 13 is located in the wall of the container 2, which allows air into the container to compensate for the volume dispensed.

Referring to figures 2 and 3, which are enlarged sections through the pump, the piston 8 has at least one channel 15 longitudinally in the wall. The sleeve 14 is a free fit between the bore of the cylinder 25 and the outside of the piston 8. By selecting the clearances between the sliding surfaces, which may vary for different viscosities of product, the longitudinal movement of the sleeve 14 with respect to the piston 8 will always lag when the piston 8 moves. The position of the piston 8 within the cylinder 25 shown in figure 2 is ready to dispense -i.e., the inside of the cylinder 25 and the cavity 17 of the piston 8 are full of product.

The sleeve 14 is at the lower part of the piston 8, with face 22 of the sleeve 14 butting against the shoulder 21 of the piston 8. There is no communication between the product 3 in the container 2 and the inside of the pump 4, because the end wall of the piston 8 is held against the resilient gasket 7 by the force of the spring 9. If the piston 8 is moved towards the nozzle 10, the drag of the product causes the rim 19 of the piston 8 to make sealing contact with the face 20 of the sleeve 14.

Referring to figure 4 (which is similar to figure 3) and figure 5, figure 4 shows the disposition of components immediately before dispensing. Referring to figure 5, when the container 2 is squeezed, the pressure P increases and exerts a force on the piston 8, urging in the direction of arrow Z. As the piston 8 moves, the resilient gasket 7 follows it a short distance, and at the same time, because the drag of the product on sleeve 14, the piston 8 moves further than the sleeve 14 until the face 20 on the sleeve 14 contacts the rim 19 of the piston 8. The sleeve 14 now blocks the channel(s) 15, so that as the piston 8 breaks away from the resilient gasket 7, there is practically no leakage of product 3 from the container 2 into the pump 4 during the discharge D of the product 3 through the nozzle 10.

Vent hole 16 is to facilitate purging of air when the dispenser is first used.

Referring to figure 6, the piston 8 and sleeve 14 have moved to the full stroke position, and face 24 of the piston 8 contacts the inner wall 23 of the cylinder 25.

This prevents the leakage of product if the user continues to squeeze the container.

On release of the squeeze, the container 2 expands to its original volume, which causes the vent valve 13 to open and admit air. At the same time, the spring 9 urges the piston back towards the container 2 in the direction of the arrow Y. Valve 11 prevents air intake to the pump 4. As the piston 8 moves, the sleeve 14 is held back by viscous drag, which opens access to the channel(s) 15. The reduced pressure in the cylinder 25 causes the product 3 to flow into the interior of the pump 4 as shown by the arrows F. At the end of the recuperation stroke, the components assume the position shown in figure 4, and the next portion may be dispensed.

Figure 8 shows the second embodiment wherein a flexible collapsible bag 26 contains the product 3, and is connected directly to the pump 4. The outer container 2 is squeezed and the rise in pressure P causes the bag 26 to compress and cause the pump 4 to function as previously described for the first embodiment.

Claims

CLAIMSI A pressure operated metering pump comprising a piston and a sleeve valve operating in a cylinder with the sleeve valve function controlled by the viscous drag of the product to be pumped said pump connected to a flexible container of product wherein the pressure to operate the pump is caused by compressing the flexible container.
2 A pressure operated metering pump as in claim I wherein the product to be dispensed is contained within an inner collapsible bag.
3 A pressure operated metering pump as in any preceding claim wherein a non-return valve permits air intake to the container to compensate for reduced volume as the product is dispensed.
4 A pressure operated metering pump wherein there is no seal component between the piston and cylinder and the sealing means is a function of the viscosity of the product to be dispensed.
5 A pressure operated metering pump as in claims 1,2, and 3 where there is a sealing component between the piston and cylinder.
6 A pressure operated metering pump as in any preceding claim wherein the pump is a cartridge and attached to the product container with a coupling.
7 A pressure operated metering pump as in any preceding claim which is integral with a coupling for attachment to the container.
8 A pressure operated metering pump as in any preceding claim having frangible tamper evidence means protecting the outlet nozzle.
9 A pressure operated metering pump as in claim 8 wherein the frangible tamper evident means seals the nozzle A pressure operated pump as in any preceding claim wherein the container is filled with the product to be dispensed.