Dispensing – Automatic control – Motor control
Patent
1998-04-20
1999-11-23
Bomberg, Kenneth
Dispensing
Automatic control
Motor control
222333, 222381, B67D 546
Patent
active
059884401
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a dispenser for liquid soap.
Soap dispensers in washrooms commonly require a user to depress a nozzle or lever in order to dispense a quantity of soap. In order to improve hygiene, attempts have been made to sense the hands of a user in the proximity of a soap dispenser, and to dispense automatically a measured quantity of soap. Such a system provides improved hygiene, and is useful, for example in hospitals, where users may have difficulty dispensing soap manually.
One known system is a wall mounted dispenser formed as an integrated soap container and outlet and having a battery operated motor which, upon detection of hands in the vicinity of a nozzle rotates a cam to cause the depression of a plunger to push soap out of the nozzle. Such a system operates at low power, and is therefore only capable of use with low viscosity soaps. Also, the physical bulk of the combined container and outlet places severe constraints on where the dispenser can be mounted, and the limited size of the soap container means that it needs frequent refilling.
It has previously been proposed to overcome some of the disadvantages of conventional soap dispensers by using a dispenser mounted, for example, on a counter and connected to a soap reservoir located remotely from the outlet. The reservoir can then be larger than a conventional soap container, and may optionally supply several different outlets. Examples of such systems are disclosed in the present applicant's earlier International application published as W095/20904, in EP-A-534743 (Inax Corporation) and in Canadian application CA 2024788 (Sloan Valve Company). All these prior art systems require relatively powerful and sophisticated pump systems located at the reservoir. For example, the present applicant's above-cited application discloses a system using a peristaltic pump which maintains soap in the supply lines to the outlets continually under pressure. In practice, the relative cost and complexity of the pump and control systems has meant that these prior art soap dispensers have not gained commercial acceptance.
According to the present invention, a liquid soap dispenser comprises a soap dispensing nozzle; a liquid soap reservoir; a plunger and cylinder which are connected between the nozzle and the soap reservoir so that soap is supplied from the reservoir to the cylinder, and from the cylinder to the nozzle upon relative movement in one direction of the plunger within the cylinder; a sensor to detect the presence of the hands of a user in the vicinity of the nozzle; a magnetic core coupled to one of the plunger and cylinder, the core being mechanically connected to a plate; and a solenoid which, in use, attracts the plate to move the core to cause the relative movement of the cylinder and plunger when a current is applied to the solenoid in response to a signal from the sensor indicating the presence of the hands of a user in the vicinity of the nozzle.
The present inventors have found that the use of a solenoid-driven plunger/cylinder pump associated with the outlet produces a system which can function in response to a proximity dectector and with sufficient power to suck soap from a reservoir which may be a few meters from the outlet, and to cope with both high and low viscosity soaps. At the same time this arrangement is sufficiently physically compact to facilitate mounting of the outlet for example on a counter, and can be produced at greatly reduced costs by comparison with prior art systems using, for example, peristaltic pumps.
Preferably, the plunger and cylinder are part of a pump comprising a pump housing which defines therein the cylinder, and a check valve which permits the entry of soap from the soap reservoir when the plunger is moved away from the check valve in a direction opposite to the one direction to allow soap to be sucked from the reservoir, but which closes when the plunger is moved in the one direction towards the check valve, wherein movement of the plunger in the one direction causes the soap to be forced
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Frost Frederick Charles
Saunders Peter
Start William
Bomberg Kenneth
F C Frost Limited
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