US 3839609 A
A pressure switch, for controlling the water level in a washing machine, is formed by a casing closed at one end by a flexible diaphragm fitted to a rim of the casing, a dished rigid cover fitted over the diaphragm to define a pressure chamber and an electric switch disposed within the casing for operation by movement of the diaphragm in response to pressure changes in the chamber.
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Description (OCR text may contain errors)
United States Patent 1 1 Pijpers [4 Oct. 1, 1974 54] PRESSURE swrrcrr HAWNG rRrssrJRE 3,617,665 11/1971 Berson 200/83 R HUSE CONNECTION THROUGH CASE AND Primary Examiner-Robert K. Schaefer MAPHRAGMI A E G Id P T l ssistam xaminerera o in  Inventor ggmg i ii Velp Attorney, Agent, or FirmMichael, Best & Friedrich  Assignee: @ontrols Company 0t America, 57 ABSTRACT Schlller Park A pressure switch, for controlling the water level in a  Filed: Sept. 26, 1973 washing machine, is formed by a casing closed at one end by a'flexible diaphragm fitted to a rim of the cas-  Appl' 400808 ing, a dished rigid cover fitted over the diaphragm to define a pressure chamber and an electric switch dis-  Foreign Application Priority Data posed within the casing for operation by movement of Sept. 27, 1972 Great Britain 44562/72 the diaphragm in response to P Changes in the chamber. 1521 Us. cu 200/83 s The pressure inlet to the Chamber is formed y a 511 in. C1. H01h 35/341 P connection integral with the, casing and having an 53 Field M Search 200 B, 3 R, 83 WM, outlet communicating with the chamber via a passage 200/83 N, 83 S, 83 V which passes through the rim of the casing, through a portion of the diaphragm sealed between the rim of 5 References (Ii/ed the casing and the cover and through a channel UNITED STATES PATENTS fonned on the inside of the cover.
3,566,060 2/1971 Phillips 200/83 R 1 Claim, 4 Drawing Figures W he 77 10 PAIENIEDHBT 11914 W w a 3.839.609
E IENI uum 1mm sum ear 2 This invention relates to pressure switches, in particular those for use in washing machines to control the level of water in the machine.
Such pressure switches conventionally comprise a cylindrical casing of plastics or metal which is closed at one end and contains one or more electric switches, a flexible diaphragm mounted on a rim at the opposite end of the casing and closing this end, and a dished cover which fits on to the rim of the casing and holds the periphery of the diaphragm in position, the cover being spaced from the diaphragm to form therebetween a pressure chamber which communicates with a pipe connection, mounted on the pressure switch casing, the pipe connection being coupled to an air trap in the washing machine via a flexible coupling pipe. The diaphragm is movable in dependence upon the pressure in the pressure chamber and has a mechanical connection to the switch or each switch to operate the switch in dependence upon the position of the diaphragm.
It is known to provide a cover made of plastics material in which the pipe connection is moulded integrally and to clamp the cover to the casing by means of a metal clamping ring. The use of a pipe connection integral with a plastics cover however increases the depth of the cover and hence the overall depth of the pressure switch, which is undesirable since such switches have to be accommodated in a washing machine in a very re stricted space. It is convenient for the cover to be made of metal so that it can be formed integrally with a clamping ring, the edge of the ring being bent under the rim of the casing to seal the cover, the diaphragm and the casing to each other. However the attachment of a pipe coupling to such a cover involves soldering and plating and consequently is expensive.
According to the present invention, there is provided a pressure switch comprising a casing having an opening at one end surrounded by a rim of the casing, a flexible diaphragm covering said opening, one or more electric switches in the casing operable by movement of the diaphragm, and a cover fltted'to the rim of the casing and forming a pressure chamber with said diaphragm, a pipe connection rigid with the casing and having an outlet passage opening beneath the cover, and a communicating passage formed in the cover from said outlet passage to the pressure chamber.
The present invention also provides a pressure switch comprising a cylindrical casing open at one end and having a pipe connection integral with a cylindrical wall of the casing and extending therefrom, the pipe connection having a lateral outlet disposed adjacent said open end of the casing, a flexible diaphragm fitted to a rim of the casing at said open end, one or more electrical switches mechanically connected to the diaphragm for operation thereby, a substantially rigid dished cover located over the diaphragm and sealed to said rim to form a pressure chamber between the cover and the diaphragm and a passage extending between the chamber and the pipe connection via a part of the diaphragm which is sealed to the rim of the casing.
One embodiment of the invention is illustrated, by way of example, in the accompanying drawing in which:
FIG. 1 is a section through a pressure switch according to the invention;
FIGS. 2 and 3 respectively are a plan and a perspective section of part of the switch of FIG. 1; and
FIG. 4 is a partial section on the line lV-IV of FIG.
As shown in the drawing, the pressure switch comprises a cylindrical plastics casing 10 closed at its lower end, the cylindrical wall of the casing having an integral radially extending pipe connection 11, and the pipe connection having a lateral outlet 12 formed in the thickened rim 13 of the casing which surrounds its open upper end.
A diaphragm 14 of rubber or other flexible material has a peripheral beading 15 which fits into a seating 16 extending around the rim of the casing. At the position at which the lateral outlet passes through the rim, the peripheral beading divides and rejoins to form an eyelet 17 registering with the outlet 12 and providing an opening through the beading.
At the centre of the diaphragm is a metal plate 18 which is connected through a post 20 to the switch or each switch of the pressure switch assembly.
A sheet'metal dished cover 21 has a peripheral flange 22 which, when the cover is in position, is folded over the rim of the casing so as to press the beading of the diaphragm between the cover and the casing rim. However, at the position at which the pipe connection joins the casing, the flange of the cover has a generally flattened area which extends into the dished portion of the cover and overlies the eyelet. This area is traversed by a semi-cylindrical groove formed on the underside of the cover which provides a communicating passage 23 extending in opposite directions from the space within the eyelet 17 of the beading, across the eyelet, and opens at its opposite end portions into the dished portion of the cover. In order to imgrove sealing between the flange of the cover and the eading, the flange of the cover is impressed on its outer surface to produce ridges 25 on the inner surface extending along, and in contact with, the beadin Thus, in operation, fluid pressure is transmitted through the outlet 12 of the pipe connection, through the eyelet 17 of the diaphragm beading, and in opposite directions through the two end portions of the communicating passage 23 into the pressure chamber 24 formed between the cover 21 and the diaphragm 14.
1. A pressure switch comprising,
a casing having a cylindrical wall having a rim defining an open end of the casing,
a hose connection integral with the casing and leading to a conduit formed in the casing,
a boss projecting from said rim,
said conduit leading through said boss,
a flexible diaphragm covering said open end and having a peripheral bead seated on said rim with an eyelet formed in the bead to fit around said boss whereby the conduit projects through the boss centrally of said eyelet,
a switch mounted in the casing and operatively connected to the diaphram,
a cover fitting over the diaphragm and forming a pressure chamber in cooperation with the diaphragm,
said cover having a flange overlying said bead and fonned to secure the cover to the casing, said flange having a channel formed therein communicating with the space between said conduit and the cover at one end and communicating with said pressure chamber at the other end of the channel.