US3356804A - Magnetically operable float switch - Google Patents

Description

il 5, 1967 R. PERL 3,356,304

MAGNETICALLY OPERABLE FLOAT SWITCH Filed Feb. 25, 1966 INVENTOR RICHARD L. PERL BY MZQQMfiM ATTORNEYS United States Patent 3,356 804 MAGNETICALLY OPERZXBLE FLOAT SWITCH Richard L. Perl, Mansfield, Ohio, assignor to The Tappan Company, Mansfield, Ohio, a corporation of Ohio Filed Feb. 25, 1966, Ser. No. 530,018 2 Claims. ('Cl. 20084) ABSTRACT OF THE DISCLOSURE A float switch for dishwashers and the like in which a magnet is carried on the center section of a float device between relatively enlarged end sections open at the bottom. The float device moves within a housing containing a magnetically operated switch, with the float device hav ing ribs at its outer surfaces and feet at the bottom to preclude locking to the housing.

This invention relates to a control device for automatic dishwashers and the like and, more particularly, to a control which will afford positive protection against overflow in the water fill operations of the machine.

While the desirability of such protection has been generally appreciated and some dishwashed models are available in which such a control is incorporated, the majority now being supplied are not so equipped and flooding is still a fairly common experience. In some areas, local regulations require a siphon break in the discharge line from the washer and the configuration usually involves a substantial bend with lateral restriction of the line. Blockage at such a restricted portion by food particles and the like often occurs, with overflow as a result of the incomplete draining in machines the controls of which are insensitive to the water actually filling the tub. Some dishwashers can overflow simply by uninformed or inadvertent manipulation of the control knob, and this malfunction is usually found to occur in the least expensive models, where the added cost of providing an automatic water fill limiting device would necessarily be a very significant factor. The devices which are now available for the purpose are reasonably complicated and quite expensive, which is believed to be the primary reason for the relatively limited use at the present time notwithstanding the obvious desirability and added user attraction and satisfaction of such a feature.

It is, therefore, a principal object of the present invention to provide a control device for overflow protection in an automatic dishwasher and the like which is of extremely simple construction, free of any practical maintenance problems, and yet so inexpensive as to present a negligible cost factor in the production of such a machine.

Another object is to provide such a control which can very readily be accommodated in conventional automatic dishwasher designs, with further economic advantage on this account.

It is another object of the present invention to provide such a control device in which a magnetic float of special configuration is employed for switch actuation responsive to the level of water within the tub of the machine, with this device thereby having a minimum of parts and not requiring maintenance attention.

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain embodiment of the invention, this being indicative, however, of but one of the various Ways in which the principle of the invention may be employed.

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In said annexed drawing:

FIG. 1 is a rear elevation of a magnetic float control switch in accordance with the present invention;

FIG. 2 is a vertical cross section of the assembly on the plane indicated by the line 22 in FIG. 1; and

FIG. 3 is a perspective view of the magnetic float used in the device.

Referring now to the drawing in detail, the new control device comprises a housing or cover generally designated by reference numeral 10 made of a material, such as nylon, which will not be adversely affected by exposure to the ordinary detergents and the like used in automatic dishwashers. This cover, which can be inexpensively molded as a single piece, is box-like, with an open back, top wall 11, bottom wall 12, front wall 13 and side walls 14.

The cover is further formed with an interior intermediate section designated generally by reference numeral 15 which depends from the top wall 11 and extends rearwardly transversely from the front wall 13. This section comprises an upper cylindrical portion 16 the rear end of which is in the plane of the open back of the cover, with an opening 17 extending completely therethrough and continuing through the front wall 13. A second cylindrical portion 18 of slightly larger diameter is beneath the upper portion 16 and is oriented in generally the same manner. However, this lower section is of such greater length as to project noticeably beyond the back plane of the cover. Moreover, while this portion 18 is also hollow, it is open at the rear and closed at the front.

As represented in FIG. 2, the device is placed within the tub of the dishwasher against the rear wall 19 of the tub and resting on the bottom wall 20. The cover 10 is securely held by means of a single attaching screw 21 inserted from the front through the centered transverse upper opening 17 and threadably through the rear tub wall 19. The lower portion 18 of the intermediate transverse section receives a conventional reed switch 22, shown as comprising a pair of normally closed blade contacts within a glass envelope, and having a pair of wires 23 which extend therefrom for appropriate connection in the control circuit for the dishwasher. The rear tub wall must of course be provided with an opening 24 to accommodate the projection of the section or portion 18 therethrough to theexterior, and such passage is sealed by a metal washer 25 and elastomeric ring 26 encircling the section at the inside of the wall.

The cover 10 is provided with lower corner openings 27 which permit the water supplied to the tub to enter the cover, with a pair of vent openings 28 provided at the front upper corner for free escape of air. The assembly and mounting is accordingly such that water filling the tub of the washer will enter and rise to the same level within the cover.

A specially designed magnetic float designated generally by reference numeral 29 is freely enclosed by the cover and this device comprises a body, again preferably molded in one piece of nylon, having inverted open bottomed box sections 30 at its respective ends and a middle section 31 of considerably reduced height with respect to the common bottom plane. This middle section defines a generally rectangular tray carrying a permanent magnet 32. As will be most clearly evident from FIG. 1, the magnetic float is dimensioned so that the end sections 30 are respectively at the sides of the depending intermediate cover section 15 and the magnet 32 is thus disposed directly below the portion in which the reed switch 22 is housed. The float body is also formed with a number of vertical ribs 33 projecting from the outer walls to preclude locking or sticking to the cover by fluid tension and extending below the bottom plane to provide feet which serve to space the body from the bottom wall 12 of the cover when the float is resting on the latter, for example, when no water is present;

It will now be apparent that as water is supplied to the tub and the interior of the cover, the float 29 will be buoyed and rise with the water, whereby the magnet is caused to approach the switch section. When the float reaches a predetermined elevation, the magnetic attraction will be suificient to open the contacts and this switch opening is of course applied to the conventional control circuit in such manner to terminate the water supply, for example, by actuation of the inlet valve to closed condition. The geometry of the float provides a low center of gravity and still allows the magnet to effectively reach the switch, the control level being established and maintained with accuracy and reliability. The open bottom form of the float permits easy molding and of course without any sealing problems. It will also be appreciated that this control will provide trouble-free operation and generally clearly meets the objectives stated hereinabove. The unit is particularly to be contrasted in this respect to pressure and weight responsive control devices which have been made available for comparable protection, but only at considerably more cost and complication of construction. Such conventional devices, furthermore, do not provide the desired control with tolerance comparable to that which can be maintained in the new magnetic float switch.

The cover preferably has a closed bottom as shown to permit the control to be used in dishwashers of different and widely varying tub bottom configurations, and the water inlet holes are sized to render the control insensitive to agitation of the water in the tub. Such inlet holes are thus large enough to permit Water to flow freely into and out of the cover, but not large enough to allow any interior wave effects. The air outlet holes are also of predetermined size so that they are large enough to prevent surface tension of the liquid from trapping the air, but not large enough to admit too much water and soil.

The reed switch can be held in place by cementing or by a suitable fastener, such as a spring clip, and it is also possible to utilize a press fit. In this last assembly, fins could be provided along the interior of the switch receiving socket for better engagement with the switch envelope. With a relatively reversed configuration, for example, with the switch at the bottom and the float of inverted U-shape to place the magnet at the top thereof rather than the bottom as shown, a normally open magnetic switch can be used which is held closed by the magnet and released when the float is raised by the water.

In the illustrated preferred embodiment, only the single screw fastener is needed for attachment, but it might be desired in some installations to employ a hinge attachment which would permit the cover to be swung upwardly to expose the interior for cleaning. The device will of course normally be designed to be inoperative as long as the water level in the tub does not exceed the anticipated level.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described provided the features stated in any of the following claims or the equivalent of such be employed.

I, therefore, particularly point out and distinctly claim as my invention:

1. A water fill control for automatic dishwashers, comprising a housing having top, bottom and side walls adapted to be mounted within a dishwasher tub adjacent the bottom thereof, said housing being provided with an upper air vent and a lower opening for free flow of water into and out of the housing with filling and draining of the tub, a magnetic switch fixed in an upper portion of the housing in sealed relation and adapted to control the supply of water'to the tub, a float movable within the housing, said float being raised and lowered with corresponding change in the level of water in the housing and relative to said switch, and a permanent magnet carried by said float, the magnet being effective to actuate the switch when raised to a predetermined height by the float, with the float having a center section at which the magnet is carried and hollow end sections of substantially greater height, the switch being located above said center section, and the float further provided with feet and ribs at its outer surfaces to preclude locking to the housing by fluid tension.

2. A control as set forth in claim 1, wherein the end sections of the float are open at the bottom.

References Cited UNITED STATES PATENTS 2,233,235 2/1941 Witthaus 73-319 2,399,111 4/1946 George 73.322.5 X 2,646,067 7/1953 Smith 200-84 X 3,149,753 9/1964 Forsyth 20084 X 3,163,731 12/1964 Lyden 200-84 BERNARD A. GILHEANY, Primary Examiner. H. A. LEWITTER, Assistant Examiner.

Claims (1)

1. A WATER FILL CONTROL FOR AUTOMATIC DISHWASHERS, COMPRISING A HOUSING HAVING TOP, BOTTOM AND SIDE WALLS ADAPTED TO BE MOUNTED WITHIN A DISHWASHER TUB ADJACENT THE BOTTOM THEREOF, SAID HOUSING BEING PROVIDED WITH AN UPPER AIR VENT A LOWER OPENING FOR FREE FLOW OF WATER INTO AND OUT OF THE HOUSING WITH FILLING AND DRAINING OF THE TUB A MAGNETIC SWITCH FIXED IN AN UPPER PORTION OF THE HOUSING IN SEALED RELATION AND ADAPTED TO CONTROL THE SUPPLY OF WATER TO THE TUB, A FLOAT MOVABLE WITHIN THE HOUSING, SAID FLOAT BEING RAISED AND LOWERED WITH CORRESPONDING CHANGE IN THE LEVEL OF WATER IN THE HOUSING AND RELATIVE TO SAID SWITCH, AND A PERMANENT MAGNET CARRIED

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