Steering wheel core structure

A steering wheel core structure comprises a hub core, polygonal in cross section with diametrically opposed, parallel peripheral faces; a spoke core with a U-shaped central portion brought into engagement with the peripheral surfaces of the hub core to clamp the same and held at the central portion between an enlarged end of the hub core and a hub bracket. The hub bracket has a finger engaged in a peripheral cut of the hub core so as to prevent relative rotation between the hub bracket and the hub core, a pair of upstanding portions engageable with upstanding portions of the spoke core so as to prevent relative rotation between the spoke core and the hub core, and a pair of horn contact portions and a pair of hub cover mounting portions cooperating to hold therebetween radial portions of the spoke core so as to prevent the spoke core from falling off from the hub bracket. The spoke core is secured at the central portion to the hub cover by projection welding and the hub bracket is secured at its base portion to the hub core by projection welding.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates in general to steering wheels for automotive 
vehicles and particularly to a core structure for reinforcement of a 
steering wheel. 
2. Description of the Prior Art 
An example of a steering wheel core structure is shown in FIGS. 6 and 7. 
The core structure consists of a metal hub core 105 splined to an end of a 
steering shaft 101 and secured thereto with a nut 103, a flange 105a 
integral with the hub core 105, a metal spoke core 107 secured by carbon 
dioxide welding A to the back face of the flange 105a and a metal hub 
bracket 109 secured by projection welding B to the front face of the 
flange 105a. With the above structure, the transfer of torque to the 
steering shaft 101 is performed through the spoke core 107, welded joint A 
and the hub core 105. The hub bracket 109 is used for installation of a 
horn spring, pad, etc. on the hub core 105. 
The prior art steering wheel core structure requires that the carbon 
dioxide welding A and projection welding B be assured and reliable so that 
vibrations of the steering wheel will not cause breakage of the welded 
joint A between the spoke core 107 and the hub core 105 or the welded 
joint B between the hub bracket 109 and the hub core 105. For this reason, 
the carbon dioxide welding A and the projection welding B must be done 
with particular care resulting in poor work efficiency and high 
manufacturing cost. 
Further, the prior art core structure inevitably requires the hub core 105 
to have the integral flange 105a in order to make the projection welding A 
assured, increasing the weight of the hub core 105, which may adversely 
affect fuel consumption of the vehicle and cause increased vibration of 
the steering wheel. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a novel and 
improved steering wheel core structure which comprises a hub core for 
installation on an end of a steering shaft, a circular handle core, a 
spoke core interconnecting the handle core and the hub core and a hub 
bracket installed on the axial end of the hub core. 
The hub core is polygonal in cross section, has a pair of diametrically 
opposed peripheral faces, and is formed with a peripheral cut at one end. 
The spoke core includes a U-shaped portion engaging the peripheral faces of 
the hub core to clamp the hub core, a pair of upstanding portions 
extending from the central portion parallel to the axis of the steering 
shaft, and a pair of radial portions extending between the upstanding 
portions and the handle core. 
The hub bracket is a single piece and includes a base portion attached to 
the hub core and formed with a finger engaged in the peripheral cut of the 
hub core so as to prevent relative rotation between the hub bracket and 
the hub core, means for defining spaces in which the upstanding portions 
of the spoke core are received and stopper means for preventing the spoke 
core falling off from the hub bracket through axial movement relative to 
the steering shaft. 
The structure of the present invention is effective for overcoming the 
above noted disadvantages and shortcomings inherent in the prior art 
structure. 
It is accordingly an object of the present invention to provide a novel and 
improved steering wheel core structure for a vehicle which can transfer 
torque from the steering wheel to the steering shaft even when the welded 
joint between the spoke core and the hub core is broken. 
It is another object of the present invention to provide a novel and 
improved steering wheel core structure of the above described character 
which can simplify the welding processes for joining the spoke core to the 
hub core. 
It is a further object of the present invention to provide a novel and 
improved steering wheel core structure of the above described character 
which can simplify the welding processes for joining the hub bracket to 
the hub core. 
It is another object of the present invention to provide a novel and 
improved steering wheel core structure which can be produced with less 
work time and manufacturing cost. 
It is a yet further object of the present invention to provide a novel and 
improved steering wheel core structure which is lighter in weight to 
improve fuel consumption of the vehicle and prevent vibration of the 
steering shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 through 5, a steering wheel core structure of this 
invention consists of a hub core 5 splined to an end of a steering shaft 1 
and secured thereto with a nut 3, a circular handle core 4, a spoke core 7 
extending between the handle core 4 and the hub core 5 and secured to the 
hub core 5 with projection welding B and a hub bracket 9 secured to an 
axial end of the hub core 5 with projection welding B. 
More specifically, the hub core 5 is polygonal in cross section, e.g. 
hexagonal as shown and is stepped at its outer periphery to have an 
enlarged end 5b while being formed with a peripheral cut 5c at an end 
opposite to the enlarged end 5b. 
The spoke core 7 is formed from a single metal rod and includes a U-shaped 
central portion 7a brought into engagement with a pair of diametrically 
opposed, parallel peripheral faces 5a, 5a of the hub core 5 and clamping 
or holding the hub core 5 tightly and rigidly, a pair of upstanding 
portions 7b, 7b extending upwards (i.e., upstanding axially of the 
steering shaft 1) from the opposite axial ends of the central portion 7a 
and a pair of radial portions 7c, 7c extending between the upstanding 
portions 7b, 7b and the handle core 4. The radial portions 7c, 7c lie in a 
plane which is offset from the plane in which the central portion 7a lies, 
by the distance corresponding to the length of the upstanding portion 7b. 
The spoke core 7 is generally circular in cross section except for the 
central portion 7a which is formed into a rectangular cross section. 
The hub bracket 9 is formed from a one-piece metal sheet and includes a 
generally rectangular, planar base portion 9g attached to the above 
described axial end of the hub core 5 and formed with a finger 9a brought 
into engagement with the peripheral cut 5 of the hub core 5, a pair of 
upstanding portions 9c, 9c extending upwards (i.e., upstanding axially of 
the steering shaft 1) from a common edge of the base portion 9g and 
located adjacent the respective longitudinal ends of same, a pair of 
elongated horn contact portions 9d extending from the upstanding portions 
9c, 9c in the same direction and in parallel with the base portion 9g, and 
a pair of elongated hub cover mounting portions 9e, 9e provided at the 
respective longitudinal ends of the base portion 9g in such a manner as to 
lie in the same plane as the base portion 9g. The upstanding portions 9c, 
9c of the hub bracket 9 are positioned in close proximity to the 
upstanding portions 7b, 7b of the spoke core 7 and adapted to provide the 
above described edge of the base portion 9g with notched portions through 
which the upstanding portions 7b, 7b of the spoke core 7 projects beyond 
the base portion 9g and also adapted to provide spaces 9b, 9b in which the 
upstanding portions 7b, 7b of the spoke core 7 are received. The horn 
contact portions 9d, 9d and the hub cover mounting portions 9e, 9e are 
adapted to clamp or hold therebetween the radial portions 7c, 7c of the 
spoke core 7 to limit movement of the spoke core 7 in the direction of 
removal or falling off from the hub bracket 9. The hub bracket 9 is 
further formed with a plurality of horn spring mounting portions 9f. 
In assembly, the spoke core 7 is secured to the hub core 5 by projection 
welding B, being held in a state that the central portion 7a of the spoke 
core 7 is put into contact with the opposed parallel faces 5a, 5a of the 
hub core 5 to clamp same as shown in FIG. 3. The hub bracket 9 is secured 
to the hub core 5 by projection welding B, being held in a state that the 
hub bracket 9 is engaged at the finger 9a in the peripheral cut 5c of the 
hub core 5 while receiving the upstanding portions 7b, 7b of the spoke 
core 7 in the spaces 9b, 9b and holding the radial portions 7c, 7c between 
the horn contact portions 9d, 9d and the hub cover mounting portions 9e, 
9e. The handle core 4 is formed from a metal rod of a circular cross 
section and secured to the opposite axial ends of the spoke core 7 by 
welding in the conventional manner. 
In operation, when the welded joint between the hub core 5 and the spoke 
core 7 by projection welding B is broken, relative rotation between the 
hub core 5 and the spoke core 7 about the axis of the steering shaft 1 is 
prevented and the transfer of torque is maintained from the steering wheel 
to the steering shaft 1 since the U-shaped central portion 7a of the spoke 
core 7 is held in engagement with the opposed parallel faces 5a, 5a of the 
hub core 5 to clamp the same tightly and rigidly as shown in FIG. 3. In 
addition to this, since the upstanding portions 7b, 7b of the spoke core 7 
are positioned in close proximity to the upstanding portions 9c, 9c of the 
hub bracket 9 and engageable with same as shown in FIG. 4, the relative 
rotation between the spoke core 7 and the hub core 5 about the axis of the 
steering shaft 1 is further prevented. On the other hand, since the spoke 
core 7 is held between the enlarged end of the hub core 5 and the base 
portion 9g of the hub bracket 9 while being held at the radial portions 
7c, 7c between the horn contact portions 9d, 9d and the hub cover mounting 
portions 9e, 9e as shown in FIG. 2, it is assuredly prevented from falling 
off from the hub core 5 and the hub bracket 9 through movement axially of 
the steering shaft 1. 
When the welded joint between the hub core 5 and the hub bracket 9 by 
projecting welding B is broken, the hub bracket 9 is prevented from 
rotation about the axis of the steering shaft 1 relative to the hub core 5 
since the hub bracket 9 is engaged at the finger 9a in the peripheral cut 
5c of the hub core 5. Further, since the hub bracket 9 is secured to the 
steering shaft 1 with the nut 3 as shown in FIG. 2, it is prevented from 
falling off of the hub core 5 through axial movement along the steering 
shaft 1. 
From the foregoing, it is to be understood that even when all of the welded 
joints are broken, the transfer of torque from the steering wheel to the 
steering shaft 1 can be retained. By this, the welding processes for 
joining the spoke core 7 and the hub bracket 9 to the hub core 5 can be 
simplified resulting in a reduced working time and therefore a reduced 
manufacturing cost. 
It is further to be understood that the hub core 5 does not require any 
integral flange, the manufacturing processes of the hub core 5 can be 
simplified and the weight of the hub core 5 can be reduced, resulting in 
improved fuel consumption of the vehicle in which the steering wheel core 
structure of this invention is utilized and making it possible to prevent 
vibrations of the steering shaft experienced with of the prior art 
structure.