ADAPTABLE PLUG, E.G. CAR PLUG FOR CIGARETTE LIGHTER HOLDER

Abstract: The present invention relates to an adaptable plug intended to be inserted into power supply hole devices (20), said plug (1) comprising a grip member (2) and an insertion member (3), wherein said insertion member (3) comprises a first contact means (6) for power connection at the bottom of the hole, and an adaptation member (5) situated in front of said grip member (2), wherein said adaptation member (5) is provided with at least one electrically conducting adaptation means (7), said adaptation means (7) comprising a base (15) and legs (14), wherein edges (16) between said legs (14) and base (15) form at least two connection areas (12), to be brought into contact to the inner wall of said power supply hole device (20) for supplying power to said plug.

Description: Adaptable plug, eg. car plug for cigarette lighter holder Field of the Invention The present invention relates to a plug, such as an adaptable plug or contact, which can be inserted into a power supply hole device. Background of the Invention There are many portable applications of today such as cellular phones, radios and video games, which are powered or charged from an electrical system of a motor vehicle, such as a car. It is common practice to insert a plug into the power supply hole device for a cigarette lighter in the motor vehicle, to obtain electrical power from the electrical system of the motor vehicle. However, the diameter of power supply holes varies from car manufacturer to car manufacturer. Inserted plugs loosens, whereby electrical contact failure occurs, for instance due to vibration when driving and the plug must be reinserted. It also occurs that the plugs get stuck in the hole, so they are difficult to get out. The adapter plugs are designed to fit into different power supply hole devices. The outer dimensions of the cylindrical plug member to be inserted into the tubular power supply hole device are defined of the most narrow power supply hole device in the market and the length of that member is defined by the deepest supply hole. These conditions result in a long and thin plug insertion member. In the top of this insertion member a tip terminal is situated for electrical connection with the bottom wall contact of the power supply hole device. Often this tip member is coil spring loaded to make the tip terminal flexible in the insertion direction. When the tip terminal is in contact with the bottom wall it is only possible to press the plug further into the hole as deep as the length of the tip teπninal allows. The purpose of the tip terminal is to allow the plug to move a short distance backwards from the bottom hole contact without losing the electrical connection with the same. The tip terminal is designed to fit into shallow tubular power supply hole devices and therefore the tip terminal is, as the insertion member is designed long, quite short in length. The electrical connection with the side walls of the tubular power supply hole device and the gripping and fastening inside the hole is provided by a number of spring contacts means projecting outwardly from the cylindrical insertion member. These contact means are placed quite close to the tip terminal. If they were placed in the other end of the insertion member instead there is a risk that the spring contacts never will reach into a shallow hole and the spring contacts will stay outside the hole without any possibility to contact the conducting side wall. However, the tubular inner wall is perforated with recesses, like holes and slits, that could destroy the spring contact means or even be destroyed by the contact means. Said recesses decrease the contact and grip area between the spring contacts and the side-walls and they are positioned closer to the bottom wall than the opening of the power supply hole device. The outer area of the inner wall, close to the opening, is not perforated and provides the best contact and grip areas in the hole. The known prior art plugs having the spring contact means positioned close to the tip member will only pass said outer area during the insertion. In the prior art, there are several examples of plugs which can be fitted into holes of different diameters, such as 20, 8-22,3 mm, without loosening even when exposed to vibration during driving etc, which plugs are also easy to unplug. EP-A1-550 945 discloses a car plug which can be firmly fitted into a power supply hole device for a cigarette lighter in an automobile, enabling stable electric connection over a long period of time irrespective of the size of the power supply hole device. The car plug has a cylindrical member provided with spring contact means projecting outwardly from the cylindrical member, whereby the projecting spring contact means contact the inner surface of the power supply hole device to obtain electrical contact. It is the power terminal provided on the inner wall of the power supply hole device that presses the terminals in the radial direction, to constitute an electric circuit, when also the tip of the plug is connected to the power terminal provided at the bottom of the power supply hole device. In this prior art car plug it can be seen that the projecting spring contact means are squeezed and fixed and the electric circuit is obtained when the tip of the tip terminal contacts the power terminal provided at the central bottom of the power supply hole device by a coil spring when forcing the car plug into the power teπninal provided at the central bottom of the power supply hole device. A disadvantage with the prior art plugs is that the force pressing the contact means of the plug to the inner wall of the power supply hole device for powering is quite weak, whereby the plugs might loosen due to vibrations. As stated above prior art adapter plugs have a number of drawbacks, which result in bad electrical contact, and fastening or gripping into said hole. Not even the above disclosed car plug solves all problems. In prior art, for instance the engagement area is small and the plugs engage deep in holes, whereby the pull-out force can be to low or if the spring terminal grab deep inside the hole where the cut-outs are located, this might destroy the power supply insertion hole or the plug, or cause a short circuit. Summary of the Disclosure The present invention relates to an adaptable plug for facilitating firmly fitting into the power supply hole device for a cigarette lighter in a vehicle, such as an automobile, being able to obtain stable electric connection irrespectively of the size of the hole, which plug is also easy to dismount. The adaptable plug according to the invention increases the forces pressing the contact means against the inner wall of the power supply hole device, by better adaptation to the inner wall of the hole compared to prior art plugs. Therefore, the contact means can also be said to work as "adaptation means", meaning that besides improved contacting, also the fitting of the plug to the inner wall of the power supply hole device is considerably increased. Thus, in the following, contact means are designated "adaptation means". When using an adapter plug in a power supply hole device that is shallower than the maximum depth it is designed for, the long insertion member will cause the plug to protrude out of the hole. The more the plug protrudes, the easier it is that the plug will move out of the hole and loose its electrical connection to the bottom wall contact as a result of the car vibrations and chokes. This problem is solved according to the invention by designing the insertion member of the plug to the shallowest power supply hole device instead of the deepest and the length of the flexible movement of the tip terminal to the difference between the shallowest and the deepest hole. Always insert the whole insertion member and still have god contact with bottom wall contact. Another problem to be solved is the bad fastening and gripping of the plug into the power supply hole device. This is solved according to the invention by placing the spring contacts means close to the rear end of the insertion member. When the insertion member has been fully inserted in the hole the spring contact means will be positioned on the outer area of the inner wall with the best electrical contact and the best fastening and gripping conditions because there is no recess in said area. One further problem to be solved is that the design of the prior art spring contact means is a limitation of the electrical contactation with the inner wall in the hole and the adaptation of the spring contacts means to the radius of the hole. To improve these features a new spring contact means is invented. Said spring contact means will adapt better to the radius of the hole and will work as a sort of electrically conducting adaptation means. This invented adaptation means has an essentially U-shaped cross section perpendicular to the insertion direction. This U-shaped adaptation means has a base and two longish legs or sidewalls extending perpendicular from the base along the two of the opposite base sides. The other two opposite sides, the front end and back end, have no legs. The front end is directed against the top of the insertion member. This construction has a two step adaptation function. The legs of the U-shaped adaptation means is first bent. The magnitude of the force to bend the legs is less than the force to bend the base of the adaptation means. First when the legs is bent as much as possible the base of the adaptation means is bent if necessary. Yet another problem is to make it easier to insert the plug into the power supply hole device. If the width of the base is increasing from the front of the adaptation means to the back end, this will increase the force needed for inserting the plug during the insertion. When the plug is fully inserted the force needed to pull the plug out of the hole therefore is maximised and the needed pulling force will reduce the more the plug is pulled out of said hole. Said two step adaptation function will also improve the insertion of the plug. In the beginning of the insertion where the base is narrower the legs will be bent. When the plug is fully inserted the base could also have been bent by the force from the inner wall of the hole, especially if the radius is small. According to a preferred embodiment of the invention, the adaptable plug is designed to be inserted into power supply hole device devices of different depth and radius, each hole device having an inner wall, said plug comprising a grip member and an insertion member, wherein said insertion member comprises a first contact for power connection at the bottom of the hole and an adaptation member having adaptation means for electrical power connection with the inner wall and situated in front of said grip member, wherein said adaptation means is/are separated from said grip member by a ring member, which bears on an opening edge of the power supply hole device and positions the adaptation means alongside with an outer area (OA) of said inner wall when the plug is fully inserted into the power supply hole device. The adaptable plug is provided with contact means for powering, working radially, thereby grabbing in the inner wall of the hole in at least two points, preferably four points, if two contact means are employed, which increases the friction area in the power supply hole device. Preferably, the adaptation means, comprising a base and legs is/are essentially U-shaped in cross section, extending in the longitudinal direction of said adaptation member, gripping around said adaptation member by its legs, wherein edges between said legs and base form at least two connection areas, to be brought into contact to the inner wall of said power supply hole device for supplying power to said adaptable plug. According to yet another embodiment of the invention, the adaptation means operate/-s according to a two step adaptation function, which implies that during the insertion of the plug into the hole device the legs are bent as much as possible before the base of the adaptation means is bent. Preferably, the width in radial direction of said adaptation means is larger than the diameter of the insertion member and the hole, whereby said adaptation member is brought into contact with the inner wall of said power supply hole device, wherein at least two connection areas are obtained. Preferably, the adaptable plug is adapted to fit holes of a length of 25-40 mm, in particular 28,5-39 mm. The adaptable plug does not come off even at intensive vibrations, even if it is fitted in a large hole, and can be fitted firmly into small holes, without implying any problems with dismounting. The adaptable plug fits holes with different diameters, and grabs just inside the hole, where there are no cutouts. Furthermore, the tip of the plug takes up different lengths of holes. An advantage is that the plug does not project a long distance from the hole, to avoid loose fitting. Another advantage is that the adaptation means always grabs where there are no cutouts. Brief Description of the Drawings The present invention will now be described in more detail with reference to preferred embodiments of the invention, given only by way of example, and illustrated in the accompanying drawings, in which: Figure 1 is a perspective view illustrating an embodiment of the invention. Figure 2a is a frontal view of an embodiment of the present invention. Figure 2b is a vertical sectional view on the central line A-A in Fig. 2a. Figure 2c illustrates a cross-section of an adaptable plug, which is inserted into a power supply hole device. Figure 3 is a plan view perpendicular to the insertion direction, illustrating the embodiment of the present invention illustrated in Fig. 1 inserted into a power supply hole device. Figure 4a-c illustrate the adaptation means to be mounted on the adaptation member illustrated in Fig. 1-2. Figure 4d illustrates the forces acting on the adaptation means according to the present invention in cross-section. Figure 4e illustrates the forces on a conventional sheet metal spring in cross-section as disclosed in for instance EP-A1-550 945. Detailed Description of the preferred embodiments According to an embodiment of the invention illustrated in Fig. 1 and 2a there is provided an adaptable plug 1 intended to be inserted into a power supply hole device 20, said plug 1 comprising a grip member 2 and an insertion member 3, wherein said insertion member 3 comprises a first contact means 6 for power connection at the bottom of the hole, and an adaptation member 5, situated in front of said grip member 2, wherein said adaptation member 5 is provided with at least one electrically conducting adaptation means 7, wherein said adaptation means 7, comprising a base 15 and legs 14, is essentially U-shaped in cross-section, extending in the longitudinal direction of said adaptation member 5, gripping around said adaptation member 5 by its legs 14, wherein edges 16 between said legs 14 and base 15 forms at least two connection areas 12, to be brought into contact to the inner wall of said power supply hole device for supplying power to said adaptable plug 1. The first member 4 is preferably essentially cylinder shaped and is preferably provided with a flange on its base side and a hole 8 in the bottom part through which the tip terminal 6 is moveable. The first member 4 can also be totally integrated into the adaptation member 5 and is not necessary. The distance D in radial direction, i. e. the width of the base 15 of said adaptation means 7 is larger than the diameter R of the insertion member 3 and the maximum diameter of the power supply hole device 20, whereby said adaptation means 7 is/are brought into contact to the inner wall of said hole, whereby at least two connection areas 12 are obtained. Preferably, two adaptation means 7 are symmetrically arranged, whereby four connection areas 12 are obtained. Figure 2C illustrates a cross-section of a plug 1, which is inserted into a power supply hole device 20. The plug 1 is fully inserted into the hole device and the ring member 13 bear on the edge 21 of the power supply hole device 20 surrounding the opening. The first contact means 6, that is the tip terminal 6, is at least so long that it will reach the electrical bottom contact 23 before the ring member 13 reaches the bottom contact 23. The spring loaded tip terminal 6 will be pushed into the cavity of the first member 4, where the spring 10 is situated, when the grip member 2 and ring member 13 are pushed towards the edge of the opening. The electrically conducting adaptation means 7 and the outer area 0A of the inner wall are now lying alongside each other. The ring-shaped outer area 0A of the inner wall 22 is not perforated and provides the best contact and grip areas in the power supply hole device. Closer to the bottom of the hole the inner wall 22 is perforated with recesses 24, like holes and slits, that often destroy prior art contact means or even are destroyed by said contact means 7. Said recesses 24 decrease the contact and grip area between the spring contacts 7 and the side walls and they are positioned closer to the bottom wall 25 than the opening of the power supply hole device. Said recesses are necessary to hold a cigarette lighter. The grip member 2 of the plug 1 and the electrical conductor 26 are the only things that protrude out of the hole. The plug will not move out of the hole and loose its electrical connection to the bottom wall contact due to the vehicle vibrations and chokes. Fig. 3 illustrates how the forces act on the adaptation means 7. The base 15 of the adaptation means 7 is bent to the inner wall of the power supply hole. Two adaptation means are illustrated, obtaining four connection areas 12 at the edges 16. Preferably, the width D of said adaptation means 7 decreases in a first portion of said adaptation means 7, to facilitate insertion of the plug 1 into the power supply hole, which is illustrated in more detail in Fig.4a. According to yet an embodiment of the invention the adaptable plug 1 comprises a grip member 2 and an insertion member 3, wherein said insertion member 3 comprises a first member 4 in the end to be inserted, provided with a hole 8 through which an essentially cylindrical tip terminal as a first contact means 6, provided with a flange at its base side, is moveable, and an adaptation member 5, an inner member 9 solidly provided partly inside said first member 4 wherein said inner member 9 protrudes towards said grip member 2 and is solidly attached thereto, a ring member 13 attached to and comprised in the grip member 2, a spring, such as a coil spring 9 provided in between said grip member 2 and said tip terminal 6 inside said plug 1, and wire lead connections 11, wherein said adaptation member 5 is provided with at least one, preferably two electrically conducting adaptation means 7, wherein said adaptation means 7, comprising a base 15 and legs 14, is essentially U- shaped in cross section, extending in the longitudinal direction of said adaptation member 5 gripping around said adaptation member 5 by its legs 14, wherein edges 16 between said legs 14 and base 15 form at least two connection areas 12, to be brought into contact to the inner wall of said power supply hole for supplying power to said adaptable plug. The adaptation means 7 are folded and protruded in the radial regions to contact the power terminal provided on the inner wall of the power supply hole for a cigarette lighter, for electrical connection. It is essential that the adaptation means 7 are folded to be flexible in radial direction. Furthermore, the adaptation means 7 can have a wire lead 11 for connection to the cord connected to the apparatus in the vehicle. The adaptation means 7 can be made of sheet metal, or of a non-conducting material, such as polymeric material, provided with a conductor thereon. The adaptation means 7 are preferably made of folded sheet metal and are further illustrated in Fig. 4a-c. In Fig. 4d, the operation of the adaptation means 7 is illustrated in more detail. The adaptation means 7, comprising a base 15 and legs 14, are essentially U-shaped in a cross-section, perpendicular to the central line A-A in Fig. 2a. The forces acting onto said adaptation means work radially, which is indicated with arrows designated F rad Compared to the contact means according to prior art, illustrated in Fig. 4e, this increases the forces acting on said adaptation means 7 considerably. In Fig. 4e it is evident that prior art only accomplish one connection area, compared to two areas for each adaptation means 7 according to the invention. It is obvious from the figures that a larger connection area 12 is obtained when using adaptation means 7 according to the invention. The broken line in Fig. 4d illustrates how the adaptation means 7 are bent by the forces acting thereon. It is also possible to exchange one of the adaptation means 7 by for instance a rib etc, to obtain three connection areas 12, in which one is non-conductive. However, this decreases the contact area. It is also possible to use non-conductive adaptation means 7 and provide the plug with conventional second contact means for power supply. The grip member 2 can comprise a hole through which the wire leads 11 are connected to apparatuses in the vehicle. The contact means 6 can be made of metal and preferably shaped like a cap with U- shaped section. However, the invention is not limited thereto. Other shapes are possible. The inner member 9 extends from the first member 4 and can be concentrically arranged around the flange of the tip terminal 6. However, it is possible to use any shape fitting inside the plug 1. The ring member 13 is preferably made of the same material as the plug 1, but is not limited thereto. If different voltages are required, it is also possible to transform the usual 12 volt current to any other required voltage before utilized in powering or recharging an appliance. This can be obtained by using different voltage transformers and incorporate them into the grip member 2. It is also possible to provide the plug 1 with noise filter. This does not, however, change the principle of the present invention, which is to improve fitting of a car plug 1 in a power supply insertion hole by means of improved force acting on the adaptation means 7, i.e., powering terminals. It will be appreciated by those of ordinary skill in the art that the number of applications above are primarily for the purpose of illustration and are not meant to imply any limitation of the present invention.

Claims: Claims 1. An adaptable plug designed to be inserted into power supply hole devices (20) of different depth and radius, each hole device (20) having an inner wall (22), said plug (1) comprising a grip member (2) and an insertion member (3), wherein said insertion member (3) comprises a first contact (6) for power connection at the bottom of the hole (25) and an adaptation member (5) having adaptation means (7) for electrical power connection with the inner wall (22) and situated in front of said grip member (2), characterised in that said adaptation means (7) is/are separated from said grip member (2) by a ring member (13), which bears on an opening edge (21) of the power supply hole device (20) and positions the adaptation means (7) alongside with an outer area (OA) of said inner wall (22) when the plug (1) is fully inserted into the hole device (20). 2. An adaptable plug according to claim 1, characterised in that said adaptation means (7), comprising a base (15) and legs (14), being essentially U-shaped in cross section, extending in the longitudinal direction of said adaptation member (5), gripping around said adaptation member (5) by its legs (14), wherein edges (16) between said legs (14) and base (15) form at least two connection areas (12), to be brought into contact to the inner wall of said power supply hole device (20) for supplying power to said adaptable plug (1). 3. An adaptable plug according to any one of the preceding claims 1-2, characterised in that said adaptation means (7) operate/-s according to a two step adaptation function, which implies that during the insertion of the plug (1) into the hole device (20) the legs (14) are bent as much as possible before the base (15) of the adaptation means (7) is bent. 4. An adaptable plug according to any one of the preceding claims 1-3, characterised in that the radial width (D) of said adaptation means (7) decreases in a first portion of said adaptation means (7), to facilitate insertion of the plug (1) into the power supply hole device (20). 5. An adaptable plug according to any one of the claims 1-4, characterised in that said adaptation means (7) are made of folded sheet metal. 6. An adaptable plug according to any one of the claims 1-5, characterised in that said contact means (6) is a tip terminal, which is movable. 7. An adaptable plug according to any one of the claims 1-6, characterised in that said contact means (6) is a tip terminal, which is movable, and the length of the tip terminal or the length of the flexible movement of said tip terminal is adapted to the difference between the shallowest and the deepest holes of the different holes devices (20) which the plug (1) is adapted to. 8. An adaptable plug according to claim 1, wherein said insertion member (3) comprises a first member (4), provided with a hole (8) through which an essentially cylindrical tip terminal (6) provided with a flange at its base side, is movable, and an adaptation member (5), an inner member (9) solidly provided partly inside said first member (4), wherein said inner member (9) protrudes towards said grip member (2) and is solidly attached thereto, a ring member (13) attached to and comprised in the grip member (2), a spring, such as a coil spring (9) provided in between said grip member (2) and said tip terminal (6) inside said plug (1), and wire lead connections (11), whereby said adaptation member (5) is provided with at least one, preferably two electrically conducting adaptation means (7), characterised in that said adaptation means (7), comprising a base (15) and legs (14) is essentially U- shaped in cross-section, extending in the longitudinal direction of said adaptation member (5) gripping around said adaptation member (5) by its legs (14), wherein edges (16) between said legs (14) and base (15) form at least two connection areas (12), to be brought into contact to the inner wall of said power supply hole device for delivering power to said adaptable plug. 9. An adaptable plug according to any one of the preceding claims, characterised in that said adaptation means (7) are of the same length as the adaptation member (5). 10. An adaptable plug according to any one of the claims 1-9, characterised in that said grip member (2) comprises a noise filter member. 11. An adaptable plug according to claim 1, characterised in that said contact means (7) is movable and attached to at least one spring (9). 12. An adaptable plug according to any one of the claims 1-11, characterised in that different voltage transformers are incorporated into the grip member (2). 13. An adaptation means intended to be provided on an adaptation member (5) on an adaptable plug (1), according to any one of the preceding claims 1-12, said adaptation means (7) comprising a base (15) and legs (14) being essentially U-shaped in cross-section, adapted to extend in the longitndinal direction of said adaptation member (5), gripping around said adaptation member (5) by its legs (14), wherein edges (16) between said legs (14) and base (15) form at least two connection areas (12) to be brought into contact to an inner wall of a power supply hole device. 14. An adaptation means according to claim 13, characterised in that said adaptation means (7) operate/-s according to a two step adaptation function, which implies that during the insertion of the plug (1) into the hole device (20) the legs (14) are bent as much as possible before the base (15) of the adaptation means (7) is bent. 15. An adaptation means according to claim 13 or 14, characterised in that the radial width (D) of said adaptation means (7) decreases in a first portion of said adaptation means (7), to facilitate insertion of the plug (1) into the power supply hole device (20). 16. An adaptation means according to any one of the preceding claims 13-15, characterised in that said adaptation means (7) are made of folded sheet metal.

Inventors: BURMAN KAJ, GABRIELSSON PER, LINDQVIST ROLAND, SJOEQVIST INGVAR, BURMAN, KAJ, GABRIELSSON, PER, LINDQVIST, ROLAND, SJOEQVIST, INGVAR
Applicants: ERICSSON TELEFON AB L M, TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
Application year: 1999
Main classification: H01R17
IPC codes: B60N3, H01R13, H01R24