Automotive Horn Switch Structure on Steering Wheel

The present invention relates to an automotive horn switch structure mounted on a steering wheel.

The present invention has a primary object to provide an improved automotive horn switch structure having component parts which can be easily assembled and secured together without the use of any screw.

The automotive horn switch structure according to the present invention includes a contact plate secured to a steering wheel, a horn spring and a fastener of an electrically insulating material securing the contact plate and the horn spring together such that the contact plate and the horn spring are electrically insulated from each other. The horn spring has at least one integral contact point adapted to be actuated by a horn button on the steering wheel into contact with the contact plate. The contact plate is electrically connected to one of plus and minus terminals of an electric power source and the horn plate is electrically connected through an electric wire to an electrically energizable horn electrically connected to the other terminal of the power source. When the contact point is actuated by the horn button, the horn is electrically energized. The fastener includes a base having first and second surfaces and self-locking resilient legs formed integrally with the base, extending from the first surface and cooperating with the base to secure the contact plate to the fastener. The improvement according to the present invention comprises a pair of spaced self-locking resilient pawls integrally formed with the base, extending from the second surface thereof and having locking claws extending toward each other. The self-locking pawls cooperate with the base to grasp and hold a part of the horn plate between the second surface and the locking claws. The electric wire has a part grasped and held between said part of the horn plate and the second surface of the base so that the wire is electrically connected to the horn plate.

FIG. 1 is a longitudinal sectional view of the prior art automotive horn switch structure mounted on a steering wheel;

FIG. 2 shows in perspective view the component parts of the prior art horn switch structure when they are in disassembled positions;

FIG. 3 is a view similar to FIG. 1 but shows an embodiment of the automotive horn switch structure according to the present invention;

FIG. 4 shows in perspective view the component parts of the horn switch structure of FIG. 2 when they are in disassembled positions;

FIG. 5 is a sectional view of a fastener shown in FIGS. 3 and 4 taken along line V--V in FIG. 6;

FIG. 6 is another sectional view of the fastener taken along line VI--VI in FIG. 5;

FIG. 7 is similar to FIG. 4 but illustrates a modified embodiment of the invention; and

FIG. 8 shows in perspective view the modified component parts shown in FIG. 7 when they are in assembled positions.

Referring to FIGS. 1 and 2 showing the prior art, an automotive steering wheel 1 includes rim and integral spoke 1a and 1b which are formed by a moulded plastic material. Rim core 1a' and spoke core 1b' are embedded in and extend through the rim 1a and spoke 1b, respectively. A bracket 1b'-1 of a metal is mechanically and electrically connected to the spoke core 1b' and mounted on the top of a projection formed integrally with the spoke 1b. A spoke cover 2 of a molded plastic material is detachably mounted on the spoke 1b to cooperate therewith to define a recess 2a having an opening 2a' formed in the spoke cover 2 and closed by a horn button 18 of a molded plastic material. The bracket 1b'-1 is electrically connected to the minus terminal of an electric power source (not shown) to form a minus terminal, as indicated by "(-)" in FIG. 1.

The recess 2a accommodates a horn switch structure which includes an elongated contact plate 4 of a metal such as phosphor bronze secured to the inner surface of the spoke cover 2 by means of screws 3 and disposed beneath the horn button 18 and electrically connected to the bracket 1b'-1. A fastener 6 of a plastic material has a generally flat upper section or base 7 and a pair of self-locking resilient legs 7a snapped into a hole 5 in the contact plate 4 to mechanically connect the contact plate 4 and the fastener 6 together. An elongated and generally arcuate horn spring 9 of a metal such as phosphor bronze has a central flat section 10 formed therein with a central hole 11 and also has downwardly projecting semi-circular contact points 12 formed at the opposite ends of the horn spring 9. A horn cord 13 includes an electric wire 14 covered with an insulating covering and having an exposed end connected to a generally sleeve-like clamping section 15 of an eye-connector 16 which is placed on the central section 10 of the horn spring 9 in alignment with the hole 11 and firmly secured to the flat base 7 of the fastener 6 together with the horn spring 9 by means of a self-tapping screw 17 extending through the eye-connector 16 and through the hole 11 into a hole 8 formed in the flat base 7 of the fastener 6, thus completing an electrical connection between one end of the horn cord 13 and the horn spring 9. The other end of the horn cord 13 is electrically connected to a conventional electrically energizable horn which is not shown but represented by "(+)" in FIG. 1. The horn button 18 has a pair of inwardly extending legs or ribs 19 engaged with the horn spring 9 at points slightly inwardly offset from the contact points 12 so that the horn spring normally upwardly resiliently biases the horn button 18 into contact with the undersurface of the inner peripheral edge of the opening 2a' formed in the spoke cover 2. The horn button 18 is inwardly or downwardly movable by an operator to downwardly resiliently deform the horn spring 9 for thereby moving at least one of the contact points 12 of the horn spring into electrical contact with the contact plate 4, so that the switch is closed to electrically connect the minus terminal 1b'-1 to the horn (not shown) to electrically energize the same.

With the described structure of the prior art horn switch, however, to connect the horn cord 13 to the horn spring 9 requires troublesome and time-consuming steps of first removing an end portion of the covering of the cord 13 to expose the end of the wire 14, either inserting the exposed end of the wire 14 into the clamping section 15 of the eye-connector 16 and deforming the clamping section 15 or securing the exposed end of the wire 14 to an eye-connector 16 by brazing, for example, and inserting the self-tapping screw 17 into the eye-connector 16 to secure the same and the horn spring 9 to the flat base 7 of the fastener 6. In addition, the prior art structure inevitably needs the relatively expensive self-tapping screw 17.

Referring first to FIGS. 3 to 6 in which the parts the same as those shown in FIGS. 1 and 2 are designated by the same reference numerals to avoid unnecessary repetition of description of the conventional or known parts, a fastener 26 formed of a molded electrically insulating plastic material, such as polyacetal or PBT resin, includes a substantially flat and quadrilateral base 27, a pair of self-locking resilient legs 27a extending from the bottom surface of the base 27 and snapped into the hole 5 in the contact plate 4 to secure the plate 4 to the fastener 27, as in the prior art described with reference to FIGS. 1 and 2, and a pair of self-locking resilient pawls in the form of substantially parallel side walls 28 extending from the top surface of the base 27 and formed along the two opposite edges thereof and substantially coextensive with these edges. The self-locking legs 27a and side walls 28 are integral with the base 27. The side walls have locking claws 28a extending toward each other, as will be best seen in FIG. 5. The locking claws 28a are each of a triangular cross-section and cooperate with the top surface of the base 27 to define a space for receiving therein the flat central section 10 of the horn spring 9. The spacing between the inner edges of the locking claws 28a is slightly smaller than the width or the dimension of the central section 10 of the horn spring 9 as measured between the side edges 10a of the section 10. The side walls 28 of the fastener 26 has a resiliency so that, when the central section 10 of the horn spring 9 is placed between the downwardly inclined surfaces of the locking claws 28a and pressed downwardly, the side walls 28 can be resiliently outwardly deformed until the side edges 10a of the central section 10 of the horn spring 9 downwardly clear the inner edges of the claws 28a. Thereafter, the resiliency returns the side walls 28 to their initial or normal upstanding positions to cause the locking claws 28a to cooperate with the flat top surface of the base 27 to grasp and hold the central section 10 of the horn spring 9.

A groove 30 is formed in the flat top surface of the base 27 and extends between the opposite side walls 28. Generally V-shaped notches 29 are formed in the side walls 28 and aligned with the groove 30 so that the bottom portions of the notches 29 are communicated with the groove 30.

An end portion of the covering of an electric cord 13 is removed to expose an end portion of the wire 14. A ball 23 of a metal such as solder or lead is fixed to the end extremity of the exposed end portion of the wire 14. Alternatively, a knot may be formed on the exposed end portion of the wire 14 at the end extremity thereof. The ball 23 or the knot may preferably has a diameter greater than the diameter of the electric cord 13.

Before the central section 10 of the horn spring 9 is snapped into locking engagement with the self-locking pawls or side walls 28 of the fastener 26, the exposed end portion of the wire 14 is placed in the notches 29 and the groove 30 formed in the fastener 26 so that the metal ball 23 or the knot mentioned above is positioned outside one of the notches 29 and the covering of the wire 14 is positioned adjacent to the other notch 29, as best shown in FIG. 5. Thereafter, the central section 10 of the horn spring 9 is snapped into locking engagement with the self-locking pawls or side walls 28. In this position, the locking claws 28a engage with the edges 10a of the central section 10 of the horn spring 9 to grasp and hold the same in face-to-face contact with the top surface of the base 27 of the fastener 26 so that the electric wire 14 now in the groove 30 is sandwiched between the base 27 of the fastener 26 and the central section 10 of the horn spring 9 to form an electrical connection between the horn spring 9 and the electric wire 14. The metal ball 23 or the knot formed on the wire 14 forms means for preventing the wire 14 from being pulled off or dislodged from the horn spring 9 and the fastener 26. The preventing means may be in any convenient form other than the metal ball 23 and the knot mentioned above.

As described, the horn spring 9 and the wire 14 of the electric cord 13 can easily be mechanically firmly connected to the fastener 26 to automatically form the electrical connection between the horn spring 9 and the wire 14. The mechanical connection does not need any screw. The electrical connection does not require any conventional wire connector. The assembling and connecting steps are greatly simplified. Thus, the described horn switch structure is suited for mass production and can be formed by reduced number of component parts and manufactured at a reduced cost.

FIGS. 7 and 8 illustrate a modification to the described embodiment of the invention. The modified embodiment includes a modified fastener 26 in which one of the side walls 28' is formed with a notch 29, as in the embodiment described above, but the other side wall 28 is formed therein with a lateral through-hole 29a disposed in alignment with a groove 30. An exposed end portion of wire 14 of the cord 13 is first so positioned as to extend across the undersurface of the central section 10 of the horn spring 9. Then, the end extremity 14' of the exposed end portion of the wire 14 is bent upwardly about an adjacent edge of the horn spring 9. The central section 10 of the horn spring 9 with the bent wire 14 attached thereto is secured to the fastener 26 in such a manner that the edge of the horn spring 9 about which the wire 14 is bent is first inserted into the elongated recess or groove formed between the locking claw of the side wall 28' and the flat top surface of the base 27 of the fastener 26 and the bend of the wire 14 is received in the through-hole 29a and, thereafter, the other edge of the horn spring 9 is snapped into the elongated recess or groove formed between the locking claw of the other side wall 28 and the flat top surface of the base 27 of the fastener 26.

The bent portion 14' of the exposed wire 14 is operative to prevent the wire 14 from being pulled away and dislodged from the horn spring 9 and the fastener 26. Thus, the modified embodiment does not require the metal ball 23 or the knot employed in the first embodiment of the invention.