AU719831B2 - Connector plug for automobiles - Google Patents

Description

AUSTRALIA

Patents Act 1990 SMK Co., Ltd.

ORIGINAL

COMPLETE SPECIFICATION STANDARD DIVISIONAL PATENT Invention Title: Connector plug for automobiles The following statement is a full description of this invention including the best method of performing it known to us:- 2 Connector plug for automobiles Technical Field The present invention relates to a connector plug which can be used with cigar lighter power sockets of different diameters in automobiles throughout the world, such as Japan, the United States, Europe, etc., and which can be smoothly inserted into and removed from these sockets.

Technique In recent years, the demand of cellular telephones has rapidly increased, and when using such telephones in an automobile, power is often drawn from a cigar lighter power socket. There has been an increased demand for a type of .:.connector plug for automobiles with a built-in DC-DC converter which can be inserted/removed into/from this cigar lighter socket.

S 15 However, in practice there are a variety of power sockets which vary according to the automobile model and the country, since the specification has not yet been standardised.

In this respect, sockets for Japanese cars and American cars are of 20.9 mm to 21.1 mm in diameter, and those for European cars are 22.1 mm to 22.3 *o 20 mm in diameter.

Even though there is a difference in the diameter of sockets, it is desired that a connector can cope with these differences in diameter.

A conventional connector plug for automobiles 10 is shown in Figs. 1 and 2. These are constituted by bending plane plate springs of narrow width for forming a contact 13. The plate springs fully protrude from a housing 11 through a window for protrusion 12, and are mounted with free movement. In the case of Fig. 3 with a large diameter socket 24, or in the case of Fig. 3 (b) with a small diameter socket 24, the differences in the diameter of the socket 24 are small, and it has been designed such that the contact 13 contacts the internal surface of the socket 24.

In Figs. 1, 2 and 3 and 14 is a fuse pipe holder portion, 15 is a fuse tube, 17 is a cap, 18 is a head terminal, 16 is a conductive coil spring to push out the head terminal 18 through the fuse tube 15, 19 is a lead wire, 20 is a power cord, 22 is an insertion hole for sliding of the contact 13 and 23 is on both side edges of the contact 13.

As mentioned above, the conventional contact 13 is constituted by bending the plane plate spring. The plate spring possesses an acute-angled portion on both side edges 23, and when inserting or removing the connector plug 10 into or out of the socket 24, there has been the problem that as both side edges 23 of the contact 13 contacts the internal surface of the socket 24, the friction resistance becomes high, and an insertion feeling is bad, as shown in Fig. 3 and The characteristic diagram shown in Fig. 4 expresses load changes against the quantity of insertion of the contact 13 into the socket 24, as shown in Fig. 3 When inserting the conventional plug 10 into the socket 24 of small diameter (dashed lines), the load is comparatively small while the S: insertion position is shallow, as seen in the region at the left-hand part of Fig. 4. The insertion feeling in this region is smooth. However, when the ".insertion position becomes deeper, the load increases rapidly, as seen in the 15 region in the right-hand part in Fig. 4. For this reason, there is a risk that the contact 13 may be broken during insertion and removal.

The present applicant has previously proposed a system to switch over the height (quantity of protrusion from the window for protrusion 12 of the housing 11) of the contact 13 by the movement of a slider 52 as shown in Fig.

In Fig. 5, the contact 13 is formed by a base 33 in the shape of straight line, a bent contact portion 34 extending from the base 33 as one body, and a 9* turned-back portion 36 formed by the tip of this contact portion 34 turned back in the shape of the letter U to the inside. The contact 13 is a pair with 2 pieces: one side (the upper side in the figure) constitutes the grounding side; and the other side (lower side in the figure) constitutes the dummy side. Between these, a lead wire 19 of a power cord 20 remains connected only to the base 33 of the contact 13 at the grounding side. It is assembled by engaging both upper and lower contacts 13 and the base 33 to a base holding groove 41 of the housing 11, as well protruding contact portions 34 from windows for protrusion 12 to the outside, and turned-back portions 36 facing circuit protective wall portions In the turned-back portion 36 of the contact 13, two-stage levels 36a and 36b are formed. In addition, sliders 52 are pressed in between the turned-back portion 36 and the circuit protective wall portion 50 in upper and lower contacts 13, respectively, and installed for possible sliding. These upper and lower slides 52 are linked as one body in the basic edge, and further, it is designed to slide by means of a knob portion 54 protruding from a sliding window 53 opened at the side of the housing 11 to the outside.

In such a configuration, when the connector plug 10 is used with a socket 24 of large diameter, as shown in Fig. 5, the slider 52 slides leftward in the figure by the knob portion 54. At that point, the slider 52 passes through a taper portion 55, pushes and widens upper and lower contacts 13, and is pressed in between the level 36a and the circuit protective wall portion 50. For such a reason, upper and lower contacts 13 are pushed outward and widened respectively, and the quantity of protrusion from the housing 11 of contact portions 34 becomes large. Therefore, it is matched with the socket 24 of large diameter.

Figure 6 shows the connector plug 10 used with a socket 24 of small diameter. If the slider 52 slides rightward in the figure, the slider 52 travels between the turned-back portion 36 and the circuit protective wall portion For this reason, upper and lower contacts 13 try to return to the original position by their elasticity. The level 36a of the turned-back portion 36 and the circuit protective wall portion 50 are then closely adhered to, and the quantity of protrusion from the housing 11 of upper and lower contacts 13 20 becomes small. Therefore, the connector plug is matched with a socket 24 of small diameter.

However, there is the problem that for the contact constituted as above, ~its shape not only becomes complicated, but also the movable mechanism acting as the slider 52 is required, making the configuration further complicated. That is to say, for the contact 13, it is necessary to provide levels 36a and 36b, and taper portion 55 in the turned-back portion 36. Furthermore, for the slider 52 it is required that there be, amongst others, a configuration to simultaneously drive upper and lower contacts 13, a configuration to slide the housing 52 inside the housing 11, and a configuration to protrude the knob portion 54 from the slide window 53. There is also the problem that the complicated mechanism of the movable portion is at risk of breaking by being used.

Disclosure of the Invention According to the invention there is provided a connector plug for connecting to a cigar lighter power socket in an automobile, the plug including a plug housing and a contact having at least some degree of free movement, the contact being formed as a plate spring in the plug housing, characterised in that the contact consists of a base composed of a conductive and elastic metal plate and a contact portion extending from the base, a tip of the contact portion is bent back towards an inner side of the contact portion to form a turned-back portion, a window for protrusion of the contact portion is formed in the housing, a circuit protective wall portion is formed inside the window, and a recessed contact escape portion is formed in the circuit protective wall portion to absorb bending of an end of the contact.

An advantage of at least some embodiments of the present invention is that a smooth insertion feeling is obtained by keeping changes in load against the amount of contact insertion within the specified range as much as possible when inserting the plug into the socket, even though diameters of sockets are 15 different.

A second advantage of at least some embodiments of the present invention is that the plug can be smoothly inserted and removed by the simple configuration, even with cigar lighter sockets of different size.

In one embodiment, the outer diameter of the dome-shaped portion is less than or substantially equal to an inside diameter of a cigar lighter power socket 24 of small diameter. Therefore, regardless of whether the socket 24 has a large diameter or a small diameter, there is a smooth contact with the inner surface of the socket 24 and a small resistance during insertion and removal. In addition, there may be an excellent insertion feeling.

In order to obtain smooth insertion and removal, one embodiment of the connector plug is formed such that the contact 13 consists of a base 33 composed of a metal plate of narrow width having conductivity and elasticity.

A contact portion 34 forms an extension of the base 33, and a turned-back portion 36 bends the tip of this contact portion 34 to the inside. A window 12 for protrusion of the contact is formed in the housing 11. A circuit protective wall portion 50 is formed inside this window 12, and there is a recessed contact escape portion 40 to absorb large bending of the tip edge of the contact 13 in the circuit protective wall portion When such a configuration is inserted into a socket 24 of large diameter, the contact portion 34 of the contact 13 is smoothly inserted and removed while contacting the internal wall of the socket 24. In addition, when the socket 24 is of large diameter, the turned-back portion 36 does not fall inwards until the recessed contact escape portion 40, but contacts the circuit protective wall portion When the plug is inserted into a socket 24 of small diameter, the tip of the contact portion 34 contacts the circuit protective wall portion 50, and when it is pushed in further, the tip portion of the contact portion 34 is turned back to fall inwards until the recessed contact escape portion 40. For this reason, the contact portion 34 of the contact 13 is inserted and removed smoothly while contacting the inner wall of the socket 24 as described before.

An advantage of at least some embodiments of the present invention, is that because the tip portion of the contact portion 34 is turned back to fall inwards until the recessed contact escape portion 40, the contact portion 34 of the contact 13 is inserted and removed smoothly while contacting the inner .:wall of the socket 24, regardless of whether the socket 24 is of large or small 15 diameter.

Brief Description of the Drawings Figure 1 is a partially-sectioned front elevation of a conventional connector plug for automobiles.

Figure 2 is a partially-sectioned front elevation of another conventional connector plug for automobiles.

Figure 3 is an enlarged cross sectional end view of a conventional connector plug as seen when inserting the plug into a socket of large diameter.

Figure 3 is an enlarged cross sectional end view of a conventional connector plug for automobiles as seen when inserting the plug into a socket of small diameter.

Figure 4 compares graphs of change in load versus contact insertion depth for a conventional connector plug and an embodiment of a connector plug according to the present invention.

Figure 5 is a partially-sectioned front view of a prior art connector plug, previously proposed by the present applicant, and is shown in use with a socket 24 of large diameter.

Figure 6 shows the connector plug of Fig. 5 in use with a socket 24 of small diameter.

Figure 7 is a front of view the lower housing of an embodiment of connector plug according to the present invention.

Figure 8 is cross sectional view through section line A-A of Figure 7.

Figure 9 is a pictorial view of an embodiment of the contact according to the present invention.

Figure 10 is an enlarged sectional front view of specific portions of the plug shown in Figure 7.

Figure 10 is a cross sectional end view through section line B-B of Figure 10 Figure 11 is an enlarged front view of a connector plug according to the present invention as seen when inserting the plug into a socket of large diameter.

Figure 11 is a cross sectional end view through section line C-C of Figure 11 Figure 12 is an enlarged front view as seen when inserting an embodiment of the connector plug into a socket of small diameter.

Figure 12 is a cross sectional end view through section line D-D of Figure 12 .e q oo* Best Mode to Carry out the Invention Figures 7, 8, and 11 show a housing composed of an upper housing 11a and a lower housing 11b dividing the cylindrical body in two in the vertical direction.

By mutually combining the two housings 11a and 11b, the front edge of the rough half (left-hand half in the figure) becomes the insertion edge which is inserted into a socket 24, and the back edge becomes a basic edge 26 to store a DC-DC converter 30 which is mainly composed of circuit elements 29. The shape of the basic edge 26 in this embodiment is conical in such a manner that the mounting side of power cord 20 gradually becomes a large diameter, but the invention is not limited to this in particular.

a surface portion of the insertion edge 25, windows for protrusion 12 are formed to allow the contact 13 to protrude. Inside this window 12, the ".circuit protective wall portion 50 is formed as one body with the housing 11.

In a hollow portion 28 formed by the two housings 11a and 11b, a printed circuit board 27 is stored and fixed to a placing board 42. In this printed circuit board 27, circuit elements 29 such as transistors, capacitors, resistors, choke coils, microcomputers, etc. are mounted, and the DC-DC converter 30 is arranged.

20 In addition to the circuit elements 29, a contact 13, coil spring 45, power cord 20, and power lamp 32, etc. are mounted as one body on the printed circuit board 27.

The shape of the contact 13, as shown in Fig. 9, is approximately formed by folding back in the shape of a letter or The base 33 is composed of a metal plate of narrow width having conductivity and elasticity, and the contact portion 34 is an extension of both sides of this base 33. In the base 33, a fixed portion 37, a horizontal holding portion 38 and a positioning projection portion 39 are formed. In both contact portions 34, dome-shaped portions 35 are formed with a constant outer diameter such that they are convexly curved to the outside, and turned-back portions 36 are formed by bending the tips of contact portions 34 to the inside. The dome-shaped portions 35 are spherically formed such that they have an outer diameter which is slightly smaller than, or roughly the same as the inside diameter of a socket 24 of relatively small diameter amongst known sockets 24.

The fixed portions 37 of the contact 13 are inserted into through holes in the approximate center of the printed circuit board 27. The contact 13 places the horizontal holding portion 38 into close contact with the upper face of the printed circuit board 27, with the tip portion of the fixed portion 37 protruding from the back of the printed circuit board 27 while being connected to the circuit pattern and fixed to the printed circuit board 27.

At a tip edge of the printed circuit board 27, an end of the coil spring having conductivity and elasticity is inserted through a through hole 46, and fixedly mounted by solder 43 at the back of the printed circuit board 27, as well as being connected to a chip-type fuse 44 by means of a circuit pattern.

At a corner of the basic edge of the printed circuit board 27, a power lamp 32 is fixed and electrically mounted by solder 43. This power lamp 32 faces a transparent plate portion 31 when stored in the housing 11.

Between the window for protrusion 12 in the housing 11 and the circuit protective wall portion 50, a projection 21 is installed as one body. The projection 21 applies an initial pressure by catching the turned-back portion 36 15 of the contact 13, which was previously bent outward.

In the tip position of the circuit protective wall portion 50, the recessed contact escape portion 40 is formed such that it absorbs a large bending at the end of the contact 13 when the plug 10 is inserted into a socket 24 of small diameter.

At a tip portion of the inserting edge 25 of the housing 11, a cap 17 with a movement hole 47 is screwed on. A head terminal 18 is inserted in the movement hole 47 of the cap 17. The head terminal 18 is able to move freely in the movement hole 47, and is spring-biased frontward by the coil spring The external diameter of the cap 17 is formed such that it can be inserted into a bimetal 49 of the smallest type of socket 24.

In the printed circuit board 27, the contact 13, coil spring 45, etc. are adhered, and circuit elements 29 for the DC-DC converter 30 are assembled, and housed in the lower housing 11b. When the contact 13 becomes engaged during insertion or removal of the plug, the contact portion 34 is initially enlarged in an external direction. As a result, the base 33 becomes engaged with a base-holding groove 41 of the housing 11. The contact portion 34 is then pushed slightly inwards, providing an initial pressure, and the turnedback portion 36 is positioned and engaged between the projection 21 and the circuit protective wall portion 50. The initial pressure is applied in two places, the base holding groove 41, and the projection 21. At that stage the initial pressure is fully applied to the contact 13, the amount of deflection of the contact 13 when plugging or unplugging the connector plug 10 to the socket 24 is made small, and there is a minimum reduction in elasticity. This allows the initial pressure to be held for a long period of time.

At this stage, since the part of the contact portion 34 which is to be enlarged in the external direction is held back by the projection 21, the bending portion at the tip of the contact portion 34 and the turned-back portion 36 is always positioned in the window for protrusion 12, even when it is inserted into a socket 24 of small diameter. In particular, it has been designed that the plug 10 can be inserted smoothly.

After the printed circuit board 27 is fixed onto the lower housing 11b, the upper housing 11a is fixed with screws onto the lower housing to form a single body. After the upper and lower housings 11a and 11b are fixed as a single body, the cap 17 with the inserted head terminal 18 is screwed on at the tip of the inserting edge 25. The coil spring is inserted into the head terminal 15 18, such that it always keeps the head terminal 18 protruding from the cap 17.

When the contact 13 is assembled as shown in Fig. 10 it is set in such a manner that an interval of the dome-shaped portion 35 (the largest interval d between the dome-shaped portions) is slightly larger than the inside diameter of a socket 24.

Figs. 11 and show an example of the configuration above in which the connector plug 10 is inserted into a socket 24 of large diameter. In this case, since the curvatures of the dome-shaped portions 35 are such that their outer diameters are slightly smaller than or approximately the same as the inside diameter of the socket 24, it is inserted and removed while smoothly contacting the inner wall of the socket 24. Furthermore, as the socket 24 is of large diameter, the turned-back portion 36 is in contact with the circuit protective wall portion 50, but does not fall into the recessed contact escape portion Figs. 12 and show an example in which the connector plug 10 is inserted into a socket 24 of small diameter. In this case, since the curvature of the dome-shaped portions 35 is a little smaller than or approximately the same as the inside diameter of this socket 24, it is inserted and removed while smoothly contacting the inner wall of the socket 24. Furthermore, as the socket 24 is of small diameter, the tip of the contact portion 34 contacts the circuit protective wall portion 50, and upon further pushing in, the tip portion of the contact portion 34 is bent in such a manner that it falls into the recessed contact escape portion In the above embodiment, the contact 13 is bent such that it approximately forms the letter or with the base portion 33 and two sections of the contact portions 34 extending from both sides of the base 33.

However, the invention is not limited to this form. It may also be made such that the contact portions are fixed respectively and individually to the printed circuit board 27, making two separate contact portions 34 which extend from each side as separate bodies. In addition, if the two contact portions 34 extending from each side are made as separate portions, it is also advantageous *to fix one of the contact portions 34 such that the lead wire 19 is connected, f.es resulting in a grounding side to the printed circuit board 27, and the other contact portion 34 as a dummy to mount to the free state, similar to the conventional method.

As above, since this embodiment is also formed with the dome-shaped portions 35 convexly curved on the outside of the contact portion 34, the dome-shaped portion 35 smoothly contacts the inner wall of the socket 24 with small friction resistance, resulting in an excellent insertion feeling.

Incidentally, there is a change in load against the depth of insertion of the contact 13, as shown with continuous lines in Fig. 4. While the inserting position is shallow, there is a smooth insertion, as seen in region'c' in the lefthand part of Figure 4. As the insertion position becomes deeper, (as seen in the region d in the right-hand part in Fig. 4) there is still a fairly smooth insertion in comparison with conventional plugs. The friction resistance is low, the insertion feeling is good, and breakages have not yet been found during insertion or removal.

As discussed, some embodiments may additionally include: a window for contact protrusion 12 in the housing 11; a circuit protective wall portion inside this window for protrusion 12; and a recessed contact escape portion to absorb a large bending of the tip edge of the contact 13 in the circuit protective wall portion 50. If the plug is inserted into a socket 24 of large diameter, or a socket 24 of small diameter, it is bent in such a manner that the tip portion of the contact portion 34 falls in until the recessed contact escape portion 40, and the contact portion 34 smoothly contacts the inner wall of the socket 24 during insertion and removal.

Since the forces which tend to widen the contact portion 34 in the external direction is reduced by the projection 21, the bending part of the tip between the contact portion 34 and the turned-back portion 36 is always located inside the window for protrusion 12, even when inserting it into a socket 24 of small diameter, and the plug 10 is smoothly inserted into the socket 24.

When adhering the contact 13 to the printed circuit board 27, the base 33 is engaged to the base-holding groove 41 of the housing 11, as it is designed that the turned-back portion 36 engages between the projection 21 and the circuit protective wall portion 50 pushing the contact portion 34. This provides the initial pressure in two places. The initial pressure to the contact 13 is applied fully, and the amount of deflection of the contact 13 is reduced o* when plugging or unplugging the socket 24. The reduction in elasticity is suppressed to the maximum, allowing the initial pressure to be held for a long *15 period of time.

Industrial Utilisation Possibility The present invention preferably can correspond with a connector plug to cigar lighter sockets for automobiles throughout the world of different 20 diameters, in Japan, the United States, Europe, etc. Not only as the connector *O00 plug for cigar lighter, but also as connector plugs for automobiles incorporating the DC-DC converter as one body, it is utilised to take out the power supply of the cellular telephone from the cigar lighter socket.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (3)

1. A connector plug for connecting to a cigar lighter power socket in an automobile, the plug including a plug housing and a contact having at least some degree of free movement, the contact being formed as a plate spring in the plug housing, characterised in that the contact consists of a base composed of a conductive and elastic metal plate and a contact portion extending from the base, a tip of the contact portion is bent back towards an inner side of the contact portion to form a turned-back portion, a window for protrusion of the contact portion is formed in the housing, a circuit protective wall portion is formed inside the window, and a recessed contact escape portion is formed in **othe circuit protective wall portion to absorb bending of an end of the contact. 0000 The connector plug as claimed in claim 1, wherein a projection formed 0W between the window and the circuit protective wall portion in the housing applies an initial pressure to the contact by catching the turned-back portion and restricting outward deflection.

3. The connector plug as claimed in claim 1, wherein an initial pressure is 0 applied to the contact in two places with a base-holding groove of the housing, and a projection, by engaging the base with the base-holding groove, and by catching the projection on the turned-back portion on the inner side of the 20 contact between the window and the circuit protective wall.

4. The connector plug as claimed in any one of the preceding claims, wherein the contact portion and the base are formed as one body. 0'0" 5. A connector plug substantially as hereinbefore describe with reference to Figures 7 to 12 of the accompanying drawings. Dated this thirteenth day of October 1999 SMK CO., LTD. Patent Attorneys for the Applicant: F B RICE CO