Pumps – Diverse pumps – Series
Patent
1998-08-17
2000-05-02
Paschall, Mark
Pumps
Diverse pumps
Series
222309, F04B 2308, G01F 1142
Patent
active
060565128
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND
1. Field of the Invention
This invention relates to a device for removing and dispensing pastes, particularly thixotropic pastes and preferably high-viscosity detergent pastes used in institutional laundries, from a flexible container provided with an opening.
2. Discussion of Related Art
Devices such as these are known, for example from DE 44 14 708 A1 or DE 44 16 089 A1. Under the effect a means for compressing the bag, for example, a roller moving down an inclined surface, the paste is forced from the containers through the opening into the feed line from which it is transported by a displacement pump, for example to a mixing chamber. In the case of detergent pastes, a stock liquor is prepared in the mixing chamber by the addition of water and can then be pumped without difficulty to the individual institutional washing machines.
However, air is unavoidably trapped in containers filled with highly viscous pastes during their production. The resulting air bubbles in the feed line lead to problems with the displacement pump and hence to an interruption in the dispensing process. These problems occur in particular with relatively old displacement pumps where the tolerances have increased through natural wear.
Dispensing problems even arise where displacement pumps capable of tolerating entrapped air are used. Although the dispensing process itself is not interrupted, its precision is affected.
Accordingly, the problem addressed by the present invention is to achieve uninterrupted precision dispensing in a device even when air is trapped in flexible containers filled with the pastes.
SUMMARY OF THE INVENTION
According to one embodiment of the invention, this problem is solved by providing a suction pump following the displacement pump. The inventors discovered that a correspondingly positioned suction pump is capable of sucking the air from the flexible bag through the displacement pump while it is running, so that a stream of paste free from air bubbles is delivered to the displacement pump.
In a preferred embodiment of the invention applicable in particular to a device for removing and dispensing detergent pastes, the suction pump is a jet pump with water as the driving medium. This type of suction pump affords advantages in terms of manufacturing and operating costs and space requirements. Also, the driving medium used may be employed for the necessary premixing of the pastes to form a stock liquor. Providing the water pressure and the nozzle cross-section are suitably selected, the throughput of water can be adjusted to correspond to the required concentration of the stock liquor. A nonreturn valve is preferably provided behind the injector.
The device according to the invention can be operated in a particularly problem-free manner if an outlet pipe is connected to the outlet of the jet pump and if its end on the jet pump side is directed upwards in operation. In this case, emptying of the jet pump after the device has been switched off is avoided so that, when the device is switched on again, the required suction pressure is immediately established without any need for additional measures.
The device according to the invention has proved to be particularly successful when the displacement pump is in the form of a screw pump, more particularly an eccentric screw pump. However, other displacement pumps may also be used in accordance with the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
One example of an embodiment of the invention is described in detail in the following with reference to the accompanying drawings, in which like items are identified by the same reference designation, wherein:
FIG. 1 is a schematic side elevation of the device.
FIG. 2 shows the outlet end of the displacement pump on a larger scale.
DETAILED DESCRIPTION OF THE INVENTION
The paste dispenser according to one embodiment of the invention comprises a rigid base frame 1. An inclined plane 2 provided in the upper region is displaceable relative to the base frame 1. A polyethylene bag filled with detergent past
REFERENCES:
patent: 4317530 (1982-03-01), Magrath
patent: 5011045 (1991-04-01), Tammi
patent: 5301847 (1994-04-01), Fehr et al.
Amberg Guenther
Huber Wolfgang
Henkel-Ecolab GmbH & Co. OHG
J. Murphy Glenn E.
Jaeschke Wayne C.
Paschall Mark
Patel Vinod D
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