Patent Grant
9478372
Many devices utilize a normally-closed or normally-open switch. Such switches often have a push button that is biased into an extended position. When the push button is in the extended position, the switch is in its normal state. For a normally-closed switch, the circuit is closed in its normal state with a moveable terminal in contact with a stationary terminal. For a normally-open switch, the circuit is open in its normal state with a moveable terminal disengaged from a stationary terminal. As a force is applied to the push button, the push button rotates into the housing of the switch. Such rotation of the push button causes the moveable terminal to move relative to a stationary terminal. In a normally-closed switch, this movement causes the moveable terminal to break contact with the stationary terminal, thus opening the circuit. Conversely, in a normally-open switch, this movement causes the moveable terminal to make contact with the stationary terminal, thus completing the circuit.
One problem that commonly occurs with such normally-closed switches is that, in some cases, the circuit never opens. For example, many refrigerators and freezers have an interior light that is off when the door is closed, but is on when the door is open. To turn such a light on or off in response to the movement of the door, a normally-closed switch is commonly installed near the door of the refrigerator or freezer. However, improper installation of the switch can lead to the circuit not opening, especially when there is a lack of quality control by the manufacturer with respect to ensuring the correct gap between the liner and the door relative to the switch location. Further compounding this problem, when the internal post member moves downward and causes the moveable terminal to break contact with the stationary terminal, it has also been observed that there is often some slight movement of the stationary terminal. In other words, the stationary terminal may move with the moveable terminal to some extent, resisting the disengagement of the moveable terminal from the stationary terminal.
Commonly assigned and co-pending U.S. patent application Ser. No. 14/185,625 describes a solution to this problem. In U.S. patent application Ser. No. 14/185,625, which again is incorporated herein by reference, the normally-closed switch further includes one or more positive stops engaging the stationary terminal at a predetermined position in the movement of the stationary terminal. Thus, the stationary terminal is prevented, at a given point, from any further movement with the moveable terminal, at least beyond the predetermined position. In other words, the positive stops substantially eliminate any resistance to the disengagement of the moveable terminal from the stationary terminal. And, as a result, the normally-closed circuit opens and closes more consistently.
There remains a need for an improved construction for such a normally-open switch that similarly ensures that the circuit opens and closes more consistently.
The present invention is a normally-open switch with positive stops.
A normally-open switch made in accordance with the present invention includes a housing that defines an internal cavity in which the internal components of the switch are housed, and the switch further includes a push button that is mounted for movement with respect to the housing. When the push button is in an extended position, a moveable terminal is disengaged from a stationary terminal, so the circuit is open. However, when a force is applied to the push button, the push button rotates into the housing about a pivot axis. Such rotation of the push button forces an internal post member, which extends between the push button and the moveable terminal, to move downward. As it moves downward, the distal end of the internal post member engages and applies pressure to the moveable terminal, causing the moveable terminal to make contact with the stationary terminal, thus closing the circuit. Once the force is no longer applied to the push button, the push button returns to the extended position, and the moveable terminal breaks contact with the stationary terminal. In this regard, the moveable terminal has sufficient resilience that it also functions like a leaf spring, providing a biasing force against the internal post member that returns the push button to the extended position.
The normally-open switch further includes one or more positive stops engaging the stationary terminal at a predetermined position in the movement of the stationary terminal. Thus, the stationary terminal is prevented, at a given point, from any further movement with the moveable terminal, at least beyond the predetermined position. In other words, the positive stops substantially eliminate any resistance to the disengagement of the moveable terminal from the stationary terminal. And, as a result, the normally-open circuit opens and closes more consistently.
The present invention is a normally-open switch with positive stops.
In this exemplary embodiment, the moveable terminal 20 is a unitary component made from a conductive material, such as copper. However, the moveable terminal 20 can be characterized as including a first portion 20a that is rigidly secured within the internal cavity defined by the housing 12 and serves as a blade connector, along with a second portion 20b that extends from the first portion 20a in a cantilever arrangement. In other words, the second portion 20b is effectively a cantilever that is anchored to the first portion 20a. When a sufficient force is applied to the distal end of the second portion 20b of the moveable terminal 20, it will deflect and rotate downward relative to the first portion 20a of the moveable terminal 20 about an axis defined by the interface between the first portion 20a and the second portion 20b. Finally, with respect to the moveable terminal 20, as best shown in
In this exemplary embodiment, the stationary terminal 24 is also a unitary component made from a conductive material, such as copper. The stationary terminal 24 can also be characterized as including a first portion 24a that is rigidly secured in the housing 12 and serves as a blade connector, along with a second portion 24b that extends from the first portion 24a. Furthermore, similar to the moveable terminal 20, in this exemplary embodiment, and as best shown in
Referring once again to the sectional views of
Referring now to
Referring still to
When the internal post member 16 moves downward and applies pressure to the moveable terminal 20, the moveable terminal 20 makes contact with the stationary terminal 24, thus closing the circuit. When the internal post member 16 is released, and the moveable terminal 20 begins to move upward, the positive stops 42, 44 prevent any further movement of the stationary terminal 24 with the moveable terminal 20, at least beyond a predetermined position, thus breaking the circuit. In other words, the positive stops 42, 44 substantially eliminate any resistance to the disengagement of the moveable terminal 20 from the stationary terminal 24. And, as a result, the normally-open circuit opens and closes the circuit more consistently.
One of ordinary skill in the art will also recognize that additional embodiments are also possible without departing from the teachings of the present invention. This detailed description, and particularly the specific details of the exemplary embodiment disclosed therein, is given primarily for clarity of understanding, and no unnecessary limitations are to be understood therefrom, for modifications will become obvious to those skilled in the art upon reading this disclosure and may be made without departing from the spirit or scope of the invention.
The present application claims priority to U.S. Provisional Patent Application Ser. No. 61/949,017 filed on Mar. 6, 2014, the entire disclosure of which is incorporated herein by reference. The present application also is directed to similar subject matter as commonly assigned U.S. patent application Ser. No. 14/185,625 filed on Feb. 20, 2014 (now U.S. Pat. No. 9,218,926), which itself claims priority to U.S. Provisional Patent Application Ser. No. 61/787,830 filed on Mar. 15, 2013, the entire disclosures of which are incorporated herein by this reference. The present application also is directed to similar subject matter as commonly assigned and co-pending U.S. patent application Ser. No. 14/631,226 entitled “Double-Throw Switch with Positive Stops” and filed on the same date as the present application, which itself claims priority to U.S. Provisional Patent Application Ser. No. 61/948,992 filed on Mar. 6, 2014, the entire disclosures of which are incorporated herein by this reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3809834 | Hipple | May 1974 | A |
| 4902863 | Fukuma | Feb 1990 | A |
| 20140042006 | Lin | Feb 2014 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 61949017 | Mar 2014 | US |
