GB1595937A

GB1595937A - Cigar lighter

Info

Publication number: GB1595937A
Application number: GB5071577A
Authority: GB
Original assignee: Societe de Signalisations Automobiles SEIMA
Current assignee: Societe de Signalisations Automobiles SEIMA
Priority date: 1977-01-12
Filing date: 1977-12-06
Publication date: 1981-08-19
Also published as: FR2377579B1; DE2755620A1; IT1089757B; SE433927B; ES232779U; FR2377579A1; DE7738068U1; SE7714837L; ES232779Y

Description

(54) CIGAR LIGHTER (71) We, SOCIETE Dn SIGNAUSATIONS AUTOMOBILES S E I M A, a French Society, of 32 rue de Paris, Saint Clement Sens, Yonnes, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a cigar lighter.

Some presently available cigar lighters are generally protected against excessive currents resulting from incorrect use or a short-circuit. This leads to serious fire risks in view of the fact that the lead connecting the cigar lighter to the battery has a large crosssection and is therefore in a position to permit the flow of high current intensities.

A previously proposed protection device provided in such cigar lighters, comprises a fuse placed in the rear portion of the cigar lighter.

However, the problem arises that normally high currents pass through this fuse and create a voltage drop which is prejudicial to the good operation of the cigar lighter. Moreover, the temperature reached by the fuse causes oxidation of the contacts, so that the operation and reliability of the system are poor.

It is an aim of the invention to alleviate the aforementioned problem, and accordingly there is provided a cigar lighter comprising a metal body in sliding engagement with an operating button, an electrical heating resistor, and heat-sensitive attachment means co-operable with the button for location in the supply circuit of the resistor when the button is in the on position, in which the heat-sensitive attachment means comprises a first bimetallic member having arms to contact the resistor when the button is in the on position, and a second bimetallic member in the form of a dish mounted at its centre and elastically bearing at its periphery on a metal part of the cigar lighter, said first and second bimetallic members being located electrically in series with one another.

The second bimetallic member may be secured either to the cigar lighter body or operating button.

Embodiments of the invention will now be described by way of example with reference to the accompanying illustrative drawings in which: Fig. 1 is an elevation of an embodiment of the second bimetallic member.

Fig. 2 is a section along the line A-A of Fig. 1.

Fig. 3 is a longitudinal sectional view of a first embodiment of the invention, and Fig. 4 is an axial sectional view of another embodiment of the invention.

The described and illustrated embodiments provide a cigar lighter which is self-protecting, that is to say automatically breaks its supply circuit in the case of an abnormal temperature rise due to incorrect use or to a short-circuit or to the total or partial earthing of one of its components and in particular its heating resistor.

In the embodiments, a second bimetallic member called a "blister strip" constituted by a bimetallic disc is fixed to the body or operating button of the cigar lighter. This strip is also inserted in the supply circuit of the heating resistor of the cigar lighter in order to suddenly switch by "blistering" from one stable state into another corresponding to a variation in its temperature.

To this end, the "blister strip" is rigidly fixed to the cigar lighter and bears elastically by its periphery to a metallic member of the cigar lighter in such a way that during an abnormal temperature rise of the bimetallic disc, either due to incorrect use or to a short-circuit, there is automatically a breaking of the supply circuit of the cigar lighter.

This state is maintained until the temperature of the bimetallic dish has dropped to a value such that it again switches into its initial position to restore the cigar lighter supply.

By means of this device it is possible to obtain significant contact cross-sections of the bimetallic dish, so that the voltage drops are small. In addition, operation is sudden and there are no periods of uncertainty of contact and consequently no disadvantages caused by high levels of heating occurring during these periods of uncertainty.

It is also pointed out that the operation of the protective member, during blistering, can be heard which attracts the attention of the user.

Moreover, in the case of a short-circuit or earthing the cigar lighter automatically produces a series of breaks followed by restoration of the power supply, the latter being so brief that it is not possible to heat the cigar lighter to a temperature which could cause a fire.

In the embodiment of Figs. 1 and 2, the blister strip 1, is made in the form of a circular bimetallic stamped dish. The intimate assembly of the two constituent metals 2 and 3 having different expansion coefficients is obtained in known manner, for example by rolling.

In this construction, the most expansible metal is disposed at 2 and the less expansible at 3. When dish 1 heats it tends to move in the direction of arrow 4, i.e. to reassume the shape of a flat disk 11. However, the stress undergone by the metal during stamping into a dish shape opposes this deformation. Thus, there is opposition between the deflecting force exerted in the direction of arrow 4 and the internal stress due to stamping and, when the force exceeds the stress, the dish 1 "blisters", i.e. it suddenly curves inwards, losing the flat shape 11 and reassuming a stable shape 5 symmetrical to the initial shape 1.

In the embodiment of Fig. 3, the periphery 8 of the blister strip 1 bears elastically on a terminal 7 for supplying electrical power to a bimetallic strip 16.

The central portion of the blister strip 1 is rigidly fixed to a body 29 by means of a nut 9 in engagement on a threaded rod 10. This rod 10 constitutes by its other end the means for fixing the bimetallic strip 16. The strip 16 has terminal hooks 161 for retaining a terminal of a heating resistor 17 when the latter is in its inserted heating position.

In this case and during the heating operation of the electrical resistor 17, the circuit is established from the terminal 7 to the resistor terminal via the bimetallic blister strip 1, the rod 10 and the bimetallic strip 16. The rod 10 is itself insulated from the terminal 7 and the body 29 by means of an insulating cylinder 11, a washer 12 and an insulating material block 13.

When the temperature of the blister strip 1 reaches an excessive value, the strip 1 blisters and takes up the position 5, indicated by dotted lines, which has the effect of immediately interrupting the power supply of the heating resistor 17. The blister strip 1 then cools and only reassumes its initial position when the temperature has dropped by a sufficient amount.

In the embodiment of Fig 3, the blister strip 1 is rigidly fixed by its centre to the end of a cigar lighter body 29. However, it can also be fixed to the cigar lighter operating button, as is for example shown in Fig. 4.

In this construction, the inner end of the heating resistor 17 is assembled by a rivet 15 to the base of a support 18 crimped onto a metal supporting member 19 which receives the head of a threaded rod 20 on which is screwed a control button 21.

A bimetallic blister strip 30 is fixed rigidly to the threaded rod 20 between the button 21 and a metal member 23. The periphery of the bimetallic strip 30 bears on an inner edge of a sleeve 26 which slides within a guide 27, itself located in a detachable manner in the body 29 of the cigar lighter.

The displacement of the sleeve 26 within the guide 27 takes place in opposition to a return spring 28.

The edge of the sleeve 26 is located between two insulating members 24 and 25. These members 24 and 25 are gripped by the threaded rod 20 between the metal member 23, which also forms the centering cylinder, and a washer 22.

Thus, on pressing in the button 21 in the direction of the arrow 31 the terminalof, the electrical resistor 17 engages on the hook 161 of the bimetallic strip 16, and this resistor 17 is energised by the following circuit: supply member 14, rod 10, bimetallic strip 16, resistor 17, rivet 15, supporting members 18, 19, threaded rod 20, member 23, bimetallic blister strip 30, sleeve 26, guide 27 and the body 29. The body 29 is connected to earth, for example to the motor vehicle due to its assembly.

However, if for any reason the temperature of the bimetallic blister strip 30 reaches an excessive value, the latter moves into the position shown by dotted lines in 33 which has the effect of interrupting the power supply of the heating resistor 17 and therefore preventing the heating temperature from reaching a value such that it is liable to cause a fire.

Obviously, the invention is not limited to the embodiments described and represented hereinbefore and various modifications- can be made thereto without passing beyond the scope of the invention as defined in the

Claims

claims. WHAT WE CLAIM IS:

1. Acigar lighter comprisingametalbody in sliding engagement with an operating button, an electrical heating resistor, and heat-sensitive attachment means co-operable with the button for location in the supply circuit of the resistor when the button is in the on position, in which the heat-sensitive attachment means comprises a first bimetallic member having arms to contact the resistor when the button is in the on position, and a second bimetallic member in the form of a dish mounted at its centre and elastically bearing at its periphery on a metal part of the cigar lighter, said first and second bimetallic members being located electrically in series with one another.

2. A cigar lighter as claimed in Claim 1 in which the second bimetallic member is secured to the body of the cigar lighter.

3. A cigar lighter as claimed in Claim 1, in which the second bimetallic member is secured to the operating button.

4. A cigar lighter as claimed in Claim 2 in which the first and second bimetallic members are secured to the lighter body by the same member.

5. A cigar lighter as claimed in Claim 3, in which the second bimetallic member and the heating resistor are secured to the operating button by the same member.

6. A cigar lighter substantially as herein described and shown in the accompanying drawings.