Electricity: circuit makers and breakers – Solid contact – Push button operated
Reexamination Certificate
2001-02-15
2002-08-27
Mai, Anh (Department: 2832)
Electricity: circuit makers and breakers
Solid contact
Push button operated
C200S341000, C200S533000, C200S573000
Reexamination Certificate
active
06441332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the art of electrical switches and, more particularly, to a switch assembly which utilizes a push button formed integral with a wedge member and at least one camming element for controlling the engagement state of a pair of electrical leads. When the push button is depressed, the wedge is moved from between electrical contacts, while the camming element pushes the contacts together.
2. Discussion of the Prior Art
It is well known in the art to provide a push button actuator for an electric or electronic switch. More specifically, it is known to utilize a plunger or push button within a housing to bias a spring member which, when pressure is applied to the push button, brings various contacts into electrical communication. Many of the recent designs represent attempts to eliminate either the number of moving parts, the number of total parts, the assembly time or assembly costs.
In a known device, a push button actuator is used to unite two electrical contacts to complete a circuit therebetween. Specifically, it is known in the art to provide a switch wherein a separating element is located between two electrical contacts. Because the contacts are biased toward each other, when the separating element is removed, the two contacts come into electrical communication and complete the circuit. U.S. Pat. No. 3,902,032 to Koepke describes an electrical switch wherein a separator element is integral with a cylindrical plunger, such that when the plunger is lowered, the separator element is removed from between a pair of electrical contacts. A spring is included which biases the plunger upwards. The biasing action of the spring causes the separator element to fit between angled sections of the electrical contacts in a default position. However, in order for this system to work, the contacts must maintain both their deformability and their internal biasing toward each other. If the contacts were to lose either of these necessary characteristics, when the separator element is removed from between the contacts, the contacts would not naturally rejoin.
In another system, the contacts are simply pushed together by an actuator. U.S. Pat. No. 1,911,444 to Fator describes a switch contained within a gripping device. In this design, two electrical contact members are biased away from each other such that, in the default position, the contacts are not in electrical communication. The entire apparatus is generally contained within a cylindrical housing, with the switch disposed in the center thereof. When the sides of the cylindrical housing are squeezed together, two plunger buttons are forced inward and push the contacts together. Although in such a system the contacts are pushed together rather than apart, the same limitations remain as discussed above.
Each of the systems described above, as well as most others in the art, do not address a second problem. It is common to have the electrical contacts extend through the housing of the switch assembly to allow for connection to the remainder of the electrical circuit. This is normally accomplished by extending the contacts below the switch assembly and attaching a respective lead wire to each. However, when attached in this fashion, the wires are often simply hanging off of the contacts. This serves as a stress location and, as such, a potential failure point for the overall switch assembly.
Switch assemblies, generally constructed in the manner set forth above, can be used in various environments. One particular environment of concern is in appliances, particularly clothes washing and drying machines. In such appliances, it is common to provide a control panel having various buttons which are associated with switches for enabling a consumer to select various operating parameters of the machine for a particular cycle. For instance, in the case of washing machines, it is common to provide a row of buttons which would enable the consumer to select a desired water temperature for both washing and rinsing cycles. It would not be uncommon to provide a bank of buttons in a single housing, with the buttons being associated with switches and further being interconnected such that the depression of one button would automatically cause the release of another button. For example, if the bank of buttons or switches control the selection between hot/hot, warm/warm, warm/cold and cold/cold wash and rinse temperatures respectively, the depression of the button associated with the warm/warm setting would automatically cause any other depressed button in the bank to be released. In general, cams and levers are utilized to interconnect the various push buttons to operate in this manner. In any event, since the useful life of such an appliance can be quite long, the switches must be extremely reliable. However, the overall construction of the switch assembly directly affects its associated cost, reflected in both the components themselves and the time needed for assembly and installation. In general, it is considered that the installation of conventional multi-switch devices are often difficult or time consuming. Primarily, the time and expense comes from being forced to install individual wires to at least two different locations of each switch in a known multi-switch device. In any event, there exists a need in the art for a push button switch assembly which overcomes the drawbacks of the prior art and which represents an overall switch which is easy to assemble, is cost effective and requires a minimum number of components, while being extremely reliable over a prolonged period of time.
SUMMARY OF THE INVENTION
The present invention is particularly directed to a switch assembly including a housing and two electrical contacts which are maintained separated from each other by a wedge. The wedge is formed integral with a push button such that, when the push button is depressed, the wedge is forced out of engagement with the contacts. This allows the contacts to come into electrical communication. A camming element, which is integral with the push button, pushes the contacts together when the push button is depressed.
The switch assembly includes a housing designed to hold the various parts of the switch assembly in place. Primarily, the contacts are attached to wires which extend outside the housing. Between the outside of the housing and where the wires are mounted to the contacts, the wires are placed in a wavy channel formed in the housing. When the housing is completely assembled, the wires are pinched and held in place between upper and lower sections of the housing which form the channel.
In a first embodiment, the push button includes a conically shaped member, which defines the camming element, with an open wide face. The contacts are positioned inside the conically shaped member such that contact elements extend into a narrowing end of the conically shaped member. The wedge extends between the contacts such that, when in place, the wedge prevents the contacts from mating. When the push button is depressed, the wedge is forced from between the contacts and allows the contacts to mate. In addition, the conically shaped member presses against the contacts and forces the contacts together. A spring is included to maintain the push button and contacts in their default positions.
In a second embodiment, instead of having a conically shaped member, two side members are provided with respective camming surfaces which essentially perform the same function as the conically shaped member of the first embodiment. In the default position, a wedge extends between the contacts and prevents their mating. When the push button is depressed, the wedge is removed and the contacts are engaged by the side members. Each side member unites with a bent section of each of the contacts and actually pushes them together. Two springs are included to maintain the push button and contacts in default positions.
Additional objects, features and advantages of the invention will become more readily appar
Crawford James F.
Sears Jeffrey L.
Wilson Harold T.
Lee Kyung S.
Mai Anh
Maytag Corporation
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