AU697531B2 - Steering wheel pad - Google Patents

Description

7- C- Af S F Ref: 317496

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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a' C C Name and Address of Applicant: Actual Inventor(s): Address for Service: Invention Title: Toyoda Gosei Co., Ltd.

1, Nagahata, Ochiai, Haruhi-cho Nishikasugai-gun Aichi-ken

JAPAN

Akio Hosoi Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Steering Wheel Pad The following statement is a full description of this invention, including the best method of performing it known to me/us:ii"' ~t 5845 STEERING WHEEL PAD BACKGROUND OF THE INVENTION The present invention relates to a steering wheel pad, and more particularly to a steering wheel pad of the center horn type, which is used for an energy absorbing pad.

A known steering wheel pad of this type includes an outer covering, which is shaped so as to cover the boss portion of a steering wheel, and an insert contained in the outer covering.

The outer covering is made of soft resin such as urethane. The insert is used for maintaining the shape of the outer covering.

In the steering wheel pad, the energy absorbing pad is constructed with an energy absorbing plate as an energy absorbing member attached in an internal space of the wheel pad.

*oa 0.0:15 when a car equipped with the steering wheel having the steering wheel pad accidentally collides with something, the o oa energy absorbing pad transmits collision energy to an energy ooo i" absorbing plate through the outer covering and the insert. As a result, the energy absorbing plate is deformed to absorb and ~o reduce the collision energy, thereby protecting a driver against the collision shock.

Examples of the steering wheel pad having such an energy 09 absorbing mechanism are shown in Published Unexamined Japanese ,r Utility Model Application Nos. Sho. 61-107660, 62-79647, and 62-187650.

When the conventional steering wheel pad thus constructed is assembled into the energy absorbing pad, the insert per se T 1 7 x I MOMM 1. ER

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in the outer covering absorbs a part of the collision energy.

The energy absorbing characteristic of the energy absorbing pad is determined by the combination of the energy absorbing plate and the insert of the steering wheel pad. To obtain a desired energy absorbing characteristic of the energy absorbing pad, a designer must shape the energy absorbing plate so as to satisfy the energy absorbing characteristic and further must shape the insert of the steering wheel pad as well so as to satisfy the energy absorbing characteristic.

For this reason, much and complicated design work is required to obtain a desired energy absorbing characteristic of the conventional energy absorbing pad.

In the steeri- wheel pad o the type which absorbs and reduces the collision energy through the outer covering and the insert, the outer covering is molded together with the insert.

Accordingly, the insert must be resistive to high temperature deformation when the outer covering is molded. For this reason, the insert has a high rigidity. Therefore, it is bi ii S difficult to destroy it.

When the steering wheel pad of the center horn type is designed to be not rigid, the central portion thereof is bent 1, by the horn operation. Thus, the horn operation feeling is not i I good.

It t S lit' SUMMARY OF THE INVENTiON S 25 Accordingly, an object of the present invention is to provide a steering wheel pad such that when it is assembled into the energy absorbing pad, the energy absorption 2 :I RT Ot 7

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characteristic of the entire energy absorbing pad may be set desirably, and a good horn operation feeling is secured.

To achieve the above object, according to a first aspect of the present invention, a steering wheel pad comprises: a thinned portion located within a region which covers a boss portion of the steering wheel, the thickness of the thinned portion being thinner than the thickness of a region outside the region; a plural number of ribs being extended in a specified direction of the assembly while being arrayed parallel to each other and further being erect on the inner surfaceat positions near the boundary of the thinned portion; and grooves being formed to have thinned groove regions while being arrayed parallel to the ribs and located at the opposite face side of base parts of the ribs.

According to a second aspect of the present invention, a steering wheel pad comprises at least one rib being disposed between and parallel to the ribs of the first aspect, and .4cU grooves being formed to have thinned groove regions in the enu *0 U.

thinned portion at both sides of the base of the rib.

According to the first aspect of the present invention, S the portion which covers the boss portion of the steering wheel S ~is thinned. A plural number of ribs are extended in a specified direction of the assembly while being arrayed parallel to each other. Further, grooves are formed in the thinned portion to have thinned groove regions while being arrayed parallel to the ribs and located at the opposite face side of base parts of the ribs. Accordingly, the structure provides a destroyed region I l l A 3i -3- ~TAii- O

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vw which is easily destroyed when it receives a load of a preset value or larger.

According to the second aspect of the present invention, the steering wheel pad comprises at least one inner rib being disposed between and parallel to the ribs of the first aspect, and grooves being formed to have thinned groove regions in the thinned region at both sides of the base of the rib.

Accordingly, the structure provides a destroyed region which is easily destroyed when it receives a load of a preset value or larger. Further, at least one rib is not easily bent when it receives a pushing force.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a plan view showing a steering wheel pad according to an embodiment of the present invention, 15 Fig. 2 is a cross sectional view taken along line X X in Fig. i, a part of the outer covering of the steering wheel being removed, Fig. 3 is a bottom view showing the steering wheel of which the outer layer is partially removed, and t '20 Fig. 4 is a cross sectional view taken along line Y Y in Fig. 3, the steering wheel pad being illustrated having a horn plate mounted thereon.

r( C DETAILED DESCRIPTION OF THE INVENTION The preferred embodiments of the present invention will be described with reference to the accompanying drawings.

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4 K~'NTO r Fig. 1 is a plan view showing a steering wheel pad according to an embodiment of the present invention. Fig.

2 is a cross sectional view taken along line X X in Fig. 1, a part of the outer covering of the steering wheel being removed. Fig. 3 is a bottom view showing the steering wheel of which the outer layer is partially removed.

As shown, a steering wheel pad 1 is formed of an outer covering 2 and an insert 3. The outer covering 2, made of relatively soft resin, is matte molded for securing a good design and a good tactual sense of the outer covering. The insert 3, made of hard resin, is provided with a necessary number of ribs. The insert 3 and the ribs are integrally molded. The material and the construction of the outer covering 2 are not different from those of the conventional one.

The insert 3 includes a region A (indicated by a broken line in Fig. which covers the upper surface of a boss portion of the steering wheel, and a region outside the region "r A. The region outside the region A has the thickness T so as to *444 44. secure a normal strength of the insert 3. The thickness T is approximately 2.8 mm, which is equal to that of the conventional pad. The region A has the thickness t of itr approximately 2 mm, which is thinner than that of the conventional one. The base parts of outer ribs 11 and 12 are 4tt c formed in the up and down direction of Fig. 1 near the boundary S 25 of the region A at both sides of the region A indicated by the broaken.line. Grooves lla and 12a are formed inside the region A defined by the broaken line, while extending in parallel with the outer ribs 11 and 12. The grooves lla and 12a are 4 .i RA4/,j ii L __L-LI i i substantially equal in length to the outer ribs 11 and 12.

Inner ribs 13 and 14 are equidistantly located between the outer ribs 11 and 12. Paired grooves 13a are formed on both sides of the base of the inner rib 13. Similarly, paired grooves 14a are formed on both sides of the base of the inner rib 14. Those pairs of the grooves 13a and 14a, which exte,,d in parallel with the inner ribs 13 and 14, are each substantially equal in length to the inner ribs 13 and 14. The inner ribs 13 and 14 are parallel with the outer ribs 11 and 12 in the longitudinal direction.

A mounting boss 20 is provided to fix a horn plate 30 (see Fig. 4) by a screw. Auxiliary ribs 20a, which assure fixing stability of the mounting boss 20, are radially and outwardly extended from the mounting boss 20. Also, a plural number of fixing bosses 21 are provided. A plate electrode 31 (see Fig.

fi 4) is securely attached to the fixing bosses 21, by screws, for example. A plural number of auxilip v ribs 21a, which assure fixing stability of the fixing bosses 21, are radially and outwardly extended from each of the fixing bosses 21. The auxiliary ribs 21a are respectively provided with guide ribs 0: 21b. The guide ribs 21b functions so as to limit the relief of i I the plate electrode 31. The guide ribs 21b functions so that Itt they are in contact with the rear side of the plate electrode 31 to increase a contact pressure against the horn plate No grooves are formed in the bases of the mounting boss and the auxiliary ribs 20a, and the fixing bosses 21 and the auxiliary ribs 21a. Terminal receiving parts 22 receive the contacts of the plate electrode 31 (Fig. The terminal g-6- RA/1 6 S-Z67-

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T O' receiving parts 22 are erect from a portion of the thickness t within the region A.

Fig. 4 is a cross sectional view taken along line Y Y in Fig. 3. In Fig. 4, the steering wheel pad 1 is illustrated having a horn plate mounted thereon.

In Fig. 4, the plate electrode 31 is firmly attached to the fixing bosses 21 by means of screws. Contacts 31a and 31b are formed at both ends of the plate electrode 31. A connection part 31c for a lead wire is located near the fixing part of the plate electrode 31. In a normal state of the steering wheel pad 1, viz., when no pressure is applied to the upper surface of the steering wheel pad, a clearance of approximately 1.2 mm is present between the contacts 31a and 31b and the horn plate As described above, the steering wheel pad 1 of the present embodiment, which is shaped so as to cover the boss portion of *00* O o a steering wheel, is -onstructed on the basis of the following technical idea according to the first aspect of the invention 0000 *o0 S which comprises: 1) a thinned portion B of a region A which a008 covers a boss portion of the steering wheel, the thickness t of the thinned portion B being thinner than the thickness T of the o region outside the region A; 2) a plural number of ribs (outer aues o a.o 00 ribs 11 and 12) being formed to extend in a specified direction 0 0 of an inner surface near the boundry of the region A of the thinned portion B, that is, in the up and down direction in o ti Fig. 3 while being arrayed parallel to each other; and 3) grooves (lla and 12a) being formed in the thinned portion B while being arrayed parallel to the outer ribs !(11ii and 12) and -7 7

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7 rt located at the opposite face side of the base parts of the outer ribs.

Thus, the thinned portion B of thickness t, which is located within the region A which covers the boss portion of the steering wheel, is thinner than the region of thickness T outside the region A. In other words, the thinned portion B is mechanically weaker than the region outside the region A. With this structure, when a car equipped with the steering wheel having the thus constructed steering wheel pad 1 accidentally collides with something, an energy absorbing pad consisting of the steering wheel pad 1 transmits collision energy to an energy absorbing plate (not shown), through the outer covering 2 and the insert 3. As a result, the energy absorbing plate is deformed to absorb and reduce the collision energy, thereby protecting a drivt:c against the collision shock.

Further, the plural number of ribs (outer ribs 11 and 12, are formed to extend in the up and down direction in Fig. 3 near the boundry of the region A of the thinned portion B while being arrayed parallel to each other. With provision of the outer ribs 11 and 12, the mechanical strength of the thinned portion B of the insert 3 is increased at the portion near the boundary of the region A. Further, the grooves 1la and 12a are *4S formed in the thinned region B while being arrayed parallel to 4 t I the outer ribs 11 and 12 and located at the opposite face side bases of the outer ribs. With provisions of the grooves lla and 12a, the mechanical strength is decreased at the groove forming parts of the insert 3. As a result, the insert 3 contains portions where the mechanical strength abruptly -8- RA1 t changes. Further, when an external force is applied to the insert 3, stress is concentrated to those grooves Ila and 12a as the thinner parts of the thinned portion B. With such a structure, the mechanical strength of the thinned region B that is thinner than the region outside the region A is remarkably reduced, thereby realizing an efficient energy absorption.

The fixing boss 20 and the auxiliary ribs 20a, and the fixing bosses 21 and the auxiliary ribs 21a are provided in the thinned portion B which is thinner than the region outside the region A. Provision of those members does not increase the mechanical strength of the thinned region B of the insert 3 since those members are not brought into contact with the fixed part of the boss portion of the steering wheel, and a clearance is present between them and the horn plate On the other hand, the steering wheel pad 1 of the present embodiment, which is shaped so as to cover the boss portion of S°a steering wheel, is constructed on the basis of the following technical idea according to the second aspect of the invention which comprises: 1) a thinned portion B of a region A which covers a boss portion of the steering wheel, the thickness t of ii I i~the thinned portion B being thinner than the thickness T of the 'it ri. t region outside the region A; 2) a plural number of ribs (outer 2 ribs 11 and 12) being formed to extend in a specified direction of an inner surface near the boundry of the region A of the thinned portion B, that is, in the up and down direction in Fig. 3 while being arrayed parallel to each other; 3) grooves (1a and 12a) being formed in the thinned portion B while being arrayed parallel to the outer ribs (11 and 12) and located at R4 -9 1- k;~f~t< the opposite face side of the base parts of the outer ribs; and 4) a plural number of inner ribs (13 and 14) with a puraJ number of pairs of grooves (13a and 14a), being disposed between the outer ribs (11 and 12), the paired grooves (13a or 14a) being formed on both sides of the inner rib (13 or 14) in the thinned portion B.

Thus, the thinned pcrtion B, which is located within the region A which covers the boss portion of the steering wheel, is thinner than the region outside the region A. In other words, the thinned region B is mechanically weaker than the region outside the region A. With this structure, when a car equipped with the steering wheel having the thus constructed steering wheel pad 1I acitdentaJ.ly collides with something, an energy absorbing pad consisting of the steering wheel pad 1 transmits collision energy to an energy absorbing plate (not shown), through the outer covering 2 and the insert 3. As a result, the energy absorbing plate is deformed to absorb and reduce the collision energy, thereby protecting a driver against the collision shock.

Further, the plural number of ribs (outer ribs 11 and 12) i are formed to extend in the up and down direction in Fig. 3 K near the boundry of the region A of the thinned portion B while 4 t being arrayed parallel to each other. With provision of the outer ribs 11 and 12, the mechanical strength of the thinned portion B of the insert 3 is increased at the portion near the boundary of the region A. Further, the grooves lla and 12a are formed in the thinned region B while being arrayed parallel to the outer ribs 11 and 12 and located at the opposite face side of the base parts of the outer ribs. With provisions of the grooves 1la and 12a, the mechanical strength is decreased at the groove forming parts of the insert 3. As a result, the insert 3 contains portions where the mechanical strength abruptly changes. Further, when an external force is applied the insert 3, stress is concentrated to those grooves lla S2a as the thinner parts of the thinned portion B. With -ich a structure, the mechanical strength of the thinned region B thaL is thinner than the region outside the region A is remarkably rduced, thereby realizing an efficient energy absorption.

Especiallt, the inner ribs 13 and 14 are provided in the thinned region B which is thinner than the region outside the region A, while being disposed between the outei ribs 11 and 12. The paired grooves 13a and 14a are further provided at both sides of the respective base parts of the inner ribs 13 4 and 14 in the thinned portion B. With such a structure, no interference is created between the outer ribs 11 and 12, I ~between the inner ribs 13 and 14, and among the inner and the outer ribs. Therefore, the structure does not increase the mechanical strength of the thinned portion B of the insert 3,

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,09:4 but increases the mechanical strength thereof against a force a that is normal to the length direction of the inner ribs 13 and 14, and the outer ribs 11 and 12. Therefore, a good horn operation feel is secured.

The fixing boss 20 and the auxiliary ribs 20a, and the fixing bosses 21 and the auxiliary ribs 21a, in addition to the inner ribs 13 an- 14, are provided in the thinned portion B 11 7: which is thinner than the region outside the region A.

Provision of those members does not increase the mechanical strength of the thinned region B of the insert 3 since those members are not brought into contact with the fixed part of the boss portion of the steering wheel, and a clearance is present between them and the horn plate In the present embodiment, the inner ribs 13 and 14, and the outer ribs 11 and 12 are equidistantly disposed on the insert 3. Therefore, the distribution of the mechanical strength is uniformly distributed over the thinned region B of the insert 3.

Accordingly, the steering wheel pad is assembled into the energy absorbing pad, and the energy absorption characteristic of the entire energy absorbing pad may be set desirably.

Further, a good horn operation feeling is secured.

"In the above-mentioned embodiment, two outer ribs 11 and 12 are provided. If required, each of the outer ribs may be divided into a plural number of segments. By so doing, the mechanical strength of the thinned region B of the insert 3 may be further reduced. Also, in the embodiment, two inner ribs 13 and 14 are provided. However, more than two inner ribs may be provided, and further each of the inner ribs may be r" "r divided into a plural number of segments. In this case, the mechanical strength may be further reduced.

The thickness t of the thinned portion B located within the region A which covers the boss portion of the steering wheel, is thinner than the thickness T of the region outside the region A. The position over the boss portion of the steering wheel is located substantially at the central portion of the pad. The thinned portion B may be located at any portion if it can reduce the mechanical strength.

In the steering wheel pad according to the first aspect of the invention, a thinned portion of a region which covers a boss portion of the steering wheel, is thinner than a region outside the region Therefore, the thinned portion is mechanically weaker than the region outside the region The plural number of ribs (11 and 12) are extended in the specified direction while being arrayed parallel to each other, and further being erect on the thinned portion at positions near the boundary of the region With provision of the outer ribs (11 and 12), the mechanical strength of the thinned portion of the insert is increased at the boundary of the region Further, grooves (lla and 12a) are formed in the thinned portion while being arrayed parallel to the outer ribs (11 and 12) and located at the opposite face side of *taa a the base parts of the outer ribs (11 and 12). With provisions 'Oat wa r o .j 2 of the grooves (lla and 12a), the mechanical strength is decreased at the groove forming parts of the insert As a result, the insert contains portions where the mechanical a strength abruptly changes. When an external force is applied to the insert stress is concentrated to those grooves (lla aJta and 12a) as the thinner parts of the thinned regicn With such a structure, the mechanical strength of the thinned region is remarkably reduced, thereby realizing an efficient energy absorption. Especially, even if various ribs are formed in the thinned region they are not brought into contact 13 :I I with the fixed part of the boss portion of the steering wheel.

Provision of those members does not increase the mechanical strength of the insert Therefore, t:iose are assembled into the energy absorbir.j pad, and the energy absorption characteristic of the entire energy absorbing pad may be set desirably.

The steering wheel pad according to the second aspect of the invention, has the following beneficial effects in addition to those of the steering wheel pad according to the first aspect. The plural number of ribs (11 and 12) are extended in the specified direction while being arrayed parallel to each other, and further being erect on the thinned region at positions near the boundary of the region With provision of the outer ribs (11 and 12), the mechanical -trength of the thinned region of the insert is increased at the boundary of the region Further, grooves (1la and 12a) arx S formed in the thinned region while being arrayed parallel to the outer ribs (11 and 12) and located at the opposite face side of the base parts of the outer ribs (11 and 12). With provisions of the grooves (1la and 12a), the mechanical strength is decreased at the groove forming parts of the insert OCe e €61 As a result, the insert contains portions where the mechanical strength abruptly changes. When an external force Ott, is applied to the insert stress is concentrated to those grooves (lla and 12a) as the thinner parts of the thinned region With such a structure, the mechanical strength of the thinned region is remarkably reduced, thereby realizing an efficient energy absorption. The inner ribs (13 and 14) are i 14

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cvi, .t I provided in the thinned region while being disposed between the outer ribs (11 and 12). The paired grooves (13a and 14a) are further provided in the inner ribs (13 and 14).

The paired grooves (13a) are formed at both sides of the inner rib Similarly, other paired grooves (14a) are formed at both sides of the inner rib With such a structure, no interference is created between the outer ribs, and the structure does not increase the mechanical strength of the thinned region but increases the mechanical strength thereof against a force that is normal to the length direction of the ribs. Accordingly, the steering wheel pad is assembled into the energy absorbing pad, and the energy absorption characteristic of the entire energy absorbing pad may be set desirably. Further, a good horn operation feeling is secured.

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