The present invention relates to electric cigar and cigarette lighters, and in particular, to such lighters for automotive applications.
Various lighters for automotive applications are known including lighters shown in the following U.S. Pat. Nos. 4,168,422, 4,204,109, 4,207,455, 4,177,374, 5,998,763, and 4,230,931.
U.S. Pat. No. 4,168,422 is exemplary of lighters of the type incorporating a switching element in the lighter unit itself. A typical electric lighter comprises a lighter unit which is removably received in an electrical socket. In the prior art device of U.S. Pat. No. 4,168,422, the lighter unit, which is insertable into and removable from the lighter socket, includes a contact switch which is activated by pushing on the lighter knob. When the switch is activated, electric power flows to the lighter heating element. When the heating element of the lighter unit reaches a sufficient temperature to ignite a cigar or cigarette (ignition temperature), a bimetallic element heated by the heating element snaps from a first, nonheated position to a second position, operating the switch to disconnect the heating element from the source of power. At the same time, once the bimetallic element activates. the lighter unit knob pops a small distance out of its housing to notify the user that the heating element is sufficiently hot to provide an ignition temperature.
The prior art device suffers from a number of deficiencies. One deficiency is that when the lighter unit is disposed in the socket, a substantially flat contact engages with a flat contact member provided in the lighter socket. Contact is maintained between the flat contact member and the flat contact of the lighter unit via the force exerted by a compression spring. Because the contact surfaces merely abut each other, there is a problem that contact may be lost, causing arcing and inoperability of the lighter.
Another problem with the prior art device is that the frictional engagement of the pop out portion of the lighter unit may be excessive and may not allow the lighter heating element to be electrically disconnected sufficiently quickly. Rapid disconnection of the lighter heating element will become an important issue in the future as automakers convert to higher voltage electrical systems. In particular, the automotive manufacturers are now planning to convert to so-called 42 volt (36 volt battery) electrical systems to satisfy the increased electrical power demands of automobiles of the future which will incorporate many more electronic and electrical functions heretofore previously performed by mechanical or hydraulic systems. It is important to provide for quick disconnection of the lighter heating element in such higher voltage electrical systems because the increased voltages will cause the heating elements to reach operating temperatures more quickly and if rapid disconnection is not made, failure of the heating element will result.
Another deficiency of the prior art lighters is that the only indication that the lighter is being heated is provided by the position of the knob of the lighter unit in the socket. When the lighter is being heated by electrical current, the knob is pushed in. When the heating element has reached operating temperature, the knob pops out. However, there is no other indication and it is not immediately obvious when looking at a lighter unit in its socket whether it is energized or de-energized by electrical current. It accordingly would be useful to have an additional indication that the lighter unit is being supplied with electrical current.
It is an object of the present invention to provide a cigar lighter assembly which ensures good electrical contact with the source of electrical power to energize the heater element. It is yet still a further object of the present invention to provide a lighter assembly which enables rapid disconnection of the heating element when the heating element has reached ignition temperature.
It is yet still a further object of the present invention to provide a lighter assembly which provides a visible indication that the heating element is being energized by electrical current other than the popped-in/popped-out position of the lighter knob.
It is yet still a further object of the present invention to provide a lighter unit which is capable of operating on the higher voltages planned for automotive electrical systems of the future without failure of the lighter heating element.
The above and other objects of the present invention are achieved a cigar lighter assembly comprising: a heating unit and a socket in which the heating unit is slidably received, the heating unit comprising first and second electrical power contacts and having a heating unit housing, the housing having an electrical heating element therein, the electrical heating element having a first end electrically connected to the first electrical power contact, the first electrical power contact comprising an annular contact element disposed at a distal end of said heating unit, the heating unit further comprising a switch, the switch having a first switch contact electrically connected to a second end of said heating element, the switch further having a second switch contact electrically connected to the second electrical power contact, and the heating unit further comprising a bimetal element for opening the switch when the electrical heating element reaches a predetermined temperature, the socket comprising a socket housing, the socket housing being sized so as to slidably and frictionally receive the heating unit housing therein, the socket housing having a base at a distal end thereof, the base being provided with a contact cup comprising a plurality of axially projecting fingers each biased radially inwardly for electrically contacting said annular contact element of said heating unit when said heating unit is inserted in said socket, and further comprising an insulating connector assembly at the distal end of said socket housing comprising at least one electrical terminal for connection to a source of electrical power, said electrical terminal being electrically connected to said contact cup.
The objects of the invention are also achieved by a cigar lighter heating unit comprising a heating unit housing, first and second electrical power contacts, the housing having an electrical heating element therein, the electrical heating element having a first end electrically connected to the first electrical power contact, the first electrical power contact comprising an annular contact element disposed at a distal end of said heating unit, for slidable contact with an electrical power source terminal, the heating unit further comprising a switch, the switch having a first switch contact electrically connected to a second end of said heating element, the switch further having a second switch contact electrically connected to the second electrical power contact, and the heating unit further comprising a bimetal element for opening the switch when the electrical heating element reaches a predetermined temperature.
According to a preferred embodiment, the heating unit further comprises an illumination device for visibly indicating that the heating element is being powered by electrical current.
The objects of the invention are also achieved by an electrical socket for a cigar lighter heating unit comprising a socket housing, the socket housing being sized so as to slidably and frictionally receive a housing of the heating unit therein, the socket housing having a base at a distal end thereof, the base being provided with a contact cup comprising a plurality of axially projecting fingers each biased radially inwardly for electrically slidably contacting an annular contact element of said heating unit when said heating unit is inserted in said socket, and further comprising an insulating connector assembly at the distal end of said socket housing comprising at least one electrical terminal for connection to a source of electrical power, said electrical terminal being electrically connected to said contact cup.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.