Land vehicles – Wheeled – Attachment
Reexamination Certificate
2000-09-12
2001-10-09
Culbreth, Eric (Department: 3611)
Land vehicles
Wheeled
Attachment
C074S552000, C200S061550
Reexamination Certificate
active
06299201
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a steering wheel mounted in a vehicle and, particularly, to a steering wheel equipped with an air bag system. More particularly, the invention relates to a steering wheel including an air bag system supported by horn-switching mechanisms.
2. Description of the Related Art
A known steering wheel of this kind is described, for example, in Japanese Utility Model Unexamined Publication No. 143734/1990 and shown in FIG.
1
. This steering wheel, generally indicated by WO, has a wheel main body
1
. An air bag system
4
is mounted at the top of the central portion of the wheel main body
1
. Each horn-switching mechanism
10
is located between the wheel main body
1
and the air bag system
4
. The wheel main body
1
includes part of the steering wheel WO and excludes the air bag system
4
and the horn-switching mechanisms
10
.
The air bag system
4
is composed of an air bag
5
, an inflator
6
, a pad
7
, and a bag holder
8
. The air bag
5
is folded so that it is capable of inflating. The inflator
6
supplies a gas used to inflate the air bag
5
. The pad
7
covers the folded air bag
5
. The bag holder
8
holds the air bag
5
, the inflator
6
, and the pad
7
.
The horn-switching mechanisms
10
are located under the bag holder
8
at opposite sides, respectively, of the holder
8
and extend forward and rearward.
FIG. 1
is a cross-sectional view of the steering wheel WO, taken in the longitudinal direction and in the front and rear direction.
Each horn-switching mechanism
10
comprises a stationary member
11
, a movable member
12
, a coil spring
16
, and a jawed bolt
19
. The stationary member
11
consists of a metal plate and is connected with a metal core
2
forming the steering wheel main body
1
. Fixed contacts
14
are mounted to the front and rear ends, respectively, of the stationary member
11
. The movable member
12
is made of a metal plate and located above the stationary member
11
. Movable contacts
15
are positioned at the front and rear ends, respectively, of the movable member
12
. The coil spring
16
is positioned between the movable member
12
and the stationary member
11
and forms a means for biasing the movable member
12
upward. The jawed bolt
19
forms a means for limiting the distance by which the movable member
12
is spaced from the stationary member
11
. The jawed bolt
19
is screwed to the metal core
2
from above the movable member
12
.
A lead wire (not shown) is connected with each movable member
12
of the horn-switching mechanisms
10
so that the movable member
12
is electrically connected with the positive side of the horn-activating circuit. Each stationary member
11
is electrically connected with the negative side of the horn-activating circuit via the metal core
2
.
The fixed contacts
14
and the movable contacts
15
together form a switch main body
Insulating spacers
17
,
18
and rubber rings
20
electrically insulate the movable members
12
from the stationary members
11
when they are in contact with both the coil springs
16
and the jawed bolts
19
.
Each movable member
12
has a mounting member (not shown) attached thereto permitting the bag holder
8
to be secured with bolts.
In the prior art steering wheel WO, the horn-switching mechanisms
10
are located on opposite sides of, and under, the heavy air bag system
4
. That is, the air bag system
4
of the prior art steering wheel WO is swingably supported by the coil springs
16
of the horn-switching mechanisms
10
that are at opposite sides of, and under, the air bag system
4
.
When the coil springs
16
, used to bias the horn-switching mechanisms
10
of the prior art steering wheel WO, have a low spring constant, the horn-switching mechanisms
10
may be inadvertently activated because the heavy air bag system
4
can easily tilt or swing horizontally due to vibrations of the vehicle.
More specifically, in the prior art steering wheel WO, the air bag system
4
and the movable member
12
are held upwardly by all the coil springs
16
. In the illustrated example, four coil springs are used. The position of the resultant center of gravity G of these supported members (the air bag system
4
and the movable member
12
) is higher than the coil springs
16
by as much as 30 mm. With the forward coil spring
16
F placed at the center of a rotation moment, a rotation moment, P×L, acts on the rear coil spring
16
B, where P is the force of a rearward swinging movement at the side of the center of gravity G and L is the distance between the center of gravity G and the coil spring
16
F in the direction of height. The rotation moment, P×L, compresses the coil spring
16
B and brings the rear movable contact
15
B into contact with the fixed contact
14
B. As a result, the switch main body
13
B is electrically activated.
Accordingly, the coil springs
16
biasing the horn-switching mechanisms
10
have high spring constants. However, when coil springs having high spring constants are used, as in the coil springs
16
, a larger load must be applied to manually activate the horn-switching mechanisms
10
. This deteriorates the feel for the horn-switching mechanisms experienced by the driver when the horn-switching mechanisms
10
are operated.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a steering wheel having horn-switching mechanisms which hold a heavy air bag system but give the driver a good feel for the manual operation of the horn-switching mechanisms.
This object is achieved by providing a steering wheel comprising a steering wheel main body having front and rear surfaces, a horn-switching assembly, and an air bag assembly. The horn-switching assembly comprises a stationary member mounted on the steering wheel main body, a support plate, a movable member movable away from and towards the support plate between a non-activated position in which said movable member is spaced by a distance from the support plate and an activated position, and a plurality of horn-switching subassemblies mounted on the support plate.
The horn-switching subassemblies respectively comprise biasing means (e.g., springs), limiting members, and switch main bodies. The biasing means are mounted between the stationary member and the movable member to collectively bias the movable member upward towards the non-activated position. The limiting members interconnect the support plate with the movable member to form an installable unit which is mountable to the stationary member and is constructed and arranged to limit the distance by which the movable member moves away from the support plate. The switch main bodies respectively comprise stationary contacts mounted on the stationary member and movable contacts mounted on the movable member. When the movable member is in the non-activated position, the stationary contacts are spaced from the movable contacts. On the other hand, when sufficient pressure is applied on the front of the steering wheel main body to overcome the biasing force of the biasing means and thereby move the movable member, the stationary contacts are electrically connected with the movable contacts.
The air bag assembly, which includes at least an air bag and inflator, is supported by the movable member of the horn-switching mechanism and is interconnected to the support plate by the limiting members.
At least one of the biasing means is mounted higher than the inflator so that the biasing means are closer than the inflator to the front surface of the steering wheel main body. Preferably, when the movable member is in the non-activated position, at least one, but preferably all, of the biasing means has a vertical center that is substantially level in height with a center of gravity of all components of the steering wheel that are collectively biased upwardly by the biasing means.
In the steering wheel in accordance with the invention, at least one biasing means is located at a height substantially equal to the he
Culbreth Eric
Dunn David R.
Pillsbury & Winthrop LLP
Toyoda Gosei Co,., Ltd.
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