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Reciprocating piston pump operating on pressure medium

Reciprocating piston pump operating on pressure medium description/claims

The present application claims priority under 35 U.S.C. § 119 to application serial number 07075373.6 filed in the European Patent Office on May 15, 2007 entitled “RECIPROCATING PISTON PUMP OPERATING ON PRESSURE MEDIUM,” which is incorporated by reference into the instant application as if set forth verbatim.

The present invention relates generally to pumps, and more particularly to reciprocating piston pumps operated with a pressure medium.

Existing reciprocating piston pumps are used to transport a medium from a pump inlet connected to a tank to a pump outlet opening. These pumps are driven by a motor that slidably moves a piston of the pump in the cylinder, thereby forming a pressure chamber in the cylinder. By opening and closing valves at the appropriate times, the pressurized fluid is propelled out of the pump. However, existing pumps require separate motors and connecting means, thereby increasing the number of parts, maintenance etc.

Accordingly there is a need for a reciprocating piston pump which is more efficient and does not require separate drive means.

This objective is achieved with the reciprocating piston pump of the present invention.

The piston of the pump will slide in the cylinder from a first to a second position by supplying the pump inlet with a pressure medium. Valve members are received or incorporated in the piston itself and are actuated by the actuating members. By opening and closing the valve members at the appropriate times, the pressure medium that is brought into the cylinder during the movement of the piston from a first position to a second position will be transferred to the other side of the piston during the piston's return from the second position to the first position. In one embodiment, during the return stroke to the first position, the first valve member is open and mutually connects the cylinder spaces on either side of the piston. During the movement of the piston from the first position to the second position, the pressure medium, which has been transferred from the pump inlet to the pressure chamber, is transported out of the pump via the pump outlet. During this piston stroke the second valve member is in an open position connecting the pressure chamber to the outlet. A pressure medium moves the piston from the first position to the second position in the cylinder, and a resilient member will urge the piston from the second position to the first position. The interplay of the resilient member and piston enables the piston pump to operate without requiring a separate motor for driving the pump. This results in a more efficient pumping and does not require separate drive means.

A preferred embodiment of the piston pump according to the present invention comprises a first plunger for uptake of a first medium from a second inlet to a second chamber.

The plunger moves from a first to a second position thereby creating an under-pressure that will cause uptake of a first medium through a second inlet of the pump. This enables transport of the first medium from a tank (or the like) to an outlet. Preferably, the pump comprises sealing means for sealing the second chamber against a return flow of medium. Advantageously, the pump comprises a connecting member connecting the first plunger with the piston to simultaneously move the plunger and piston. Through this simultaneous movement of the plunger and piston, both the pressure medium and the first medium are transported to the pump outlet. In other words, the movement of the piston, either by the pressure medium or the resilient means, causes uptake and transport of the first medium to the pump outlet. Preferably, the pump outlet for the first medium and the pressure medium is the same. Therefore, a mixture of the pressure medium with the first medium is provided. For example, in the case of the pressure medium being water and the first medium being a soap concentrate, such a mixture would result in a liquid soap ready for use.

In a further preferred embodiment according to the present invention the pump further comprises a second plunger for uptake of a second medium from a third inlet to a third chamber.

By moving the second plunger from a first position to a second position an under-pressure will be created in the third chamber. This will cause uptake of a second medium from a third inlet. This will enable transport of this second medium from a tank (or the like) to an outlet. Preferably, the pump comprises second sealing means for sealing the third chamber against a return flow of medium. Further, the second pump preferably comprises a second connecting member connecting the second plunger to the piston (and preferably also to the first plunger) to simultaneously move the piston and second plunger (and preferably the first plunger) for transport of the pressure medium, and second medium (and preferably also the first medium) to the pump outlet. In a preferred embodiment, the pump outlet for the pressure medium, the first medium, and the second medium are the same. This results in a mixture of these media in the outlet flow. For example, in the case of the pressure medium being water and the first and second media being soap concentrates, the outflow of the pump will be a liquid soap ready for use. Preferably, the third inlet is at a different position as the second inlet to enable uptake of two different media, or the same medium at different altitudes in a tank with different densities. In case of the third inlet taking media from the same tank it is possible to have a mixture at the pump outlet of the pressure medium and two different densities of the other medium thereby creating a consistent mixture.

In a further preferred embodiment according to the present invention the pump a comprises float member for connecting the third inlet to the second chamber.

By the use of the float member it is possible to keep the third inlet at the upper level of, for example, a storage tank with decreasing level as the pumping operation continues. With the float member keeping the third inlet at a different level as compared to the second inlet during the pumping operation density differences in a storage tank are compensated. Preferably, the float member comprises a pivoting member to ensure the third pump inlet remains above the second inlet. Also preferably, the float member comprises a lock for locking and unlocking the pivoting member. This enables the float member to float on the top surface of the fluid in, for example, a storage tank. Therefore, the third inlet can be positioned just below this top level. As fluid is removed by the pumping operation, and the level in the tank thus decreases, the float member will pivot around the pivoting member to remain floating on the medium and thereby keeping the third inlet just below this top level. By providing a lock it is possible to put the piston pump into a storage tank after which the lock is disabled and the float member unlocked. The piston pump may then start operation. In case the piston pump needs to be removed from the storage tank the float member may be retracted to its original position by enabling the lock. This may be relevant, for example, when a storage tank is not fully empty and the pump needs to be removed.

In a further preferred embodiment according to the present invention the pump further comprises at least one shock absorber with a plunger.

When the piston moves from the first position to the second position, and medium is transported from the pressure chamber to the pump outlet, part of the outgoing medium is temporarily stored by the absorber. This stored volume is output during the return movement of the piston from the second position to the first position due to the compressed air volume on the other side of the plunger. This smoothens the pump output.

In a further preferred embodiment according to the present invention the pump further comprises disposing means for disposing an amount of an agent medium in at least one chamber.

The disposing means will provide a certain amount of one or more agents into one of the chambers of the piston pump during a stroke of the piston and/or plungers. Such agent may include a colouring agent supplying a specific colour to the inlet space of the pressure medium, thereby colouring the outflow from the piston pump. This will be relevant e.g. in case the outflow of the piston pump has the same colour as the incoming flow. E.g. in case of the pressure medium being water and the first and/or second medium being a soap concentrate a colouring agent will enable to distinguish the ingoing water from the outgoing soap. Also other agents may be used to provide specific characteristics to the outflow of the piston pump. Preferably, the pump comprises connecting means for connecting the tank of agents medium to the pump. This enables the provision of a single piece of equipment for both the pump and the agent disposal means. Furthermore, by directly coupling the agent medium to the pump it is possible to use the movement of the piston for disposal of the agent in the main pressure chamber related to this piston.

In a further preferred embodiment according to the present invention the pressure medium is a fluid.

A fluid, like water, used for the pressure medium would allow for movement of the piston in the cylinder. Furthermore, as the piston is moved due to the resilient means, the fluid is transported to the pump outlet and preferably mixed with one or two other media like, for example, soap concentrate. Such soap concentrate may constitute of a mix of various chemicals with a rather large variation of molecular weight. This concentrate may be taken from a storage tank. Typically, after a relatively short period of time, such as about 5 minutes, it is possible to distinguish an upper part of, for example, 60% low density concentrate and a lower part of, for example, 40% higher density concentrate. To achieve a consistent outflow of soap at the pump outlet such a mixture must reflect the differences in density of the soap concentrate. In the example mentioned here, 60% of the soap concentrate has to be taken from the upper part by the third inlet of the pump and the remaining 40% of the lower part by the second inlet of the pump. Depending on the desired characteristics of the soap product, the ratio of soap to water will vary. Different ratios may be achieved by changing the dimensions of the pump parts. For example, different uptakes of volume from the storage tank by the second and/or third inlet will be possible. By choosing the second and third chambers of the desired dimensions it is possible to have an outflow with every desired concentrations of media. Although in the preferred embodiment the ratio of the first pressure chamber and second chamber is about 1:11, also ratios 1:10 and 1:12 are possible. However, it will be understood that far different ratios will be possible, such as anywhere between 1:1 and 1:100, depending on the density differences in the relevant media. This will include the ratios 1:23 and 1:35 that are also relevant for soap concentrates.

The volumes of the chambers used by the first and second plunger have to be chosen according to the characteristics of the soap concentrate. In the example mentioned here, this ratio would be 2:3, although ratios between 1:2 and 2:1 would also be possible. However, it will be understood that ratios anywhere from 1:100 to 100:1 would also be possible.

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