Cigar lighter with thermal safety device

#The invention relates to cigar and cigarette lighters, especially those for motor vehicles. More precisely, the invention relates to cigar lighters with a thermal safety device.

#Cigar lighters of this kind are already known, comprising a heating body and a knob 1 intended to be engaged in the heating body. This knob 1 includes a heating resistance element 3 placed in a cup 5 (see FIGS. 1 and 2). This heating resistance element can be supplied with electricity via a supply bimetallic strip in contact with the cup when the knob is pushed into the heating position in the heating body. When this cigar lighter is put into use, the knob is pushed in within the body until the cup is latched onto by the bimetallic strip. When the temperature of the heating resistance element is sufficient, the supply bimetallic strip deforms, cutting off the passage of current in the heating resistance element and allowing the releasing of the knob which comes back into gripping position.

#However, if a person or an object continues to exert a force on the knob while it is being heated, or if jamming occurs in the knob, the latter can no longer come back into gripping position. A cyclic phenomenon is then set up: the supply bimetallic strip deforms and cuts off the electrical contact, the cigar lighter cools down progressively and the supply bimetallic strip then comes back to its initial position, re-activating the heating until the supply bimetallic strip again deforms so as to cut off the heating. This cycle occurs until external intervention unblocks the knob. Throughout this time, the electrical harness connected to the cigar lighter conducts the heat given off, by the heating cycle, within the heating body. This may entail damage to the insulation of the electrical cables, damage to the cigar lighter itself, as well as other accidents, such as a fire.

#FIGS. 1 and 2 represent a cigar lighter knob, in diagrammatic section, passing through the longitudinal axis of this knob;

#FIG. 3 represents a cigar lighter in accordance with the present invention, in diagrammatic section, passing through its longitudinal axis;

#FIG. 4 represents a detail of the cigar lighter represented in FIG. 3, in diagrammatic section, passing through its longitudinal axis, the sectional plane of FIG. 4 being turned by 90° with respect to the sectional plane of FIG. 3, about the longitudinal axis.

#One particular but not limiting embodiment of the cigar lighter 10 in accordance with the present invention is described in detail below in relation to FIGS. 3 and 4.

#As represented in FIG. 3, what is involved is a cigar lighter 10, to be flush-mounted on a dashboard 20 of a motor vehicle. The cigar lighter 10 has an overall cylindrical geometry, about a longitudinal axis 0—0.

#The knob 1 includes a fixed part 23 and a moveable part 25.