WO1997047509A1

WO1997047509A1 - Hub plate assembly for a steering wheel

Info

Publication number: WO1997047509A1
Application number: PCT/US1997/008874
Authority: WO
Inventors: Gregory F. Exner; Sheryar Durani
Original assignee: Breed Automotive Technology, Inc.
Priority date: 1996-06-14
Filing date: 1997-05-22
Publication date: 1997-12-18
Also published as: DE19781812T1; GB2330807A; GB9824941D0

Abstract

A hub plate assembly (26) comprises a hub plate (34) having an axial bore (38), a pair of transverse slots (40, 42), and a gear (36) including a gear portion (44) and a threaded shaft (46) extending from the gear portion. The threaded shaft is disposed in the axial bore and is received in a threaded bore of a steering column shaft. The transverse slots provide access to the gear for driving the gear. The hub plate assembly includes a removable tool (48) which preferably includes a worm gear (50) which drives the gear (36) to attach or detach the hub plate assembly to a steering column shaft. The two transverse slots each provide access to the gear for driving the gear in opposite directions for attachment or detachment.

Description

HUB PLATE ASSEMBLY FOR A STEERING WHEEL

The present invention relates generally to a hub plate assembly for a steering wheel, particularly for a modular steering wheel assembly. The hub plate assembly includes a hub plate with at least one transverse slot which provides access to a gear disposed in the hub plate for improved securement and detachment of a steering wheel on a steering column shaft.

The inclusion of an airbag into a steering wheel presented some complications to automotive designers m the attachment of both the airbag and the steering wheel. Historically, the designer was required to allow access to attachment structure for the steering wheel, and then subsequent access to the airbag assembly for attachment. Finally, a trim cover had to be place over the airbag. More recently, proposals have been made for so-called modular steering wheel assemblies. In a modular steering wheel assembly, the airbag and steering wheel may be preassembled and then attached to the vehicle after preassembly.

One modular steering wheel assembly includes a hub plate, a worm gear and a complementary gear. The worm gear is adapted to drive the complementary gear for securing the assembly to a steering column shaft. The worm gear remains after attachment, which increases the cost and weight of the steering wheel assembly. The attachment forces between a steering wheel assembly and a steering column shaft must be relatively high to prevent detachment of the steering wheel assembly from the steering column shaft. Attachment or removal of a steering wheel assembly from the steering column shaft can be problematic due to these forces.

One complication to a designer of a modular steering wheel assembly is how to achieve these high securement forces with attachment structure that would still be accessible after the attachment of the airbag to the steering wheel.

The known art has not successfully addressed these problems. Accordingly, there remains a need for a cost-effective structure for attaching a steering wheel assembly to a steering column shaft.

The steering wheel assembly of the present invention includes a hub plate having an axial bore, at least one transverse slot, and a gear having a gear portion and a threaded shaft extending from the gear portion. The threaded shaft is disposed in the axial bore and the slot provides access to the gear portion. A removal worm gear is selectively moved into the slot for driving the gear for attachment to a steering column shaft . The worm is preferably used to both secure and release the wheel. In a preferred embodiment, the hub plate includes two transverse slots, wherein a first slot provides access for driving the gear in a first direction, and a second slot provides access to the gear for driving the gear in a second direction. The removable worm is inserted into a first of the slots to drive the gear for attachment, and into the other of the slots to drive the gear for detachment. By utilizing the two slots, the invention overcomes a problem that would exist with a single slot, due to the forces between the removable tool and the gear. The forces would move the removable tool outwardly of the slot in one of attachment or detachment if a single slot was utilized. The use of the two slots ensures that the forces on the tool are urging the tool further into the slot during both attachment and detachment.

By utilizing the removable tool, the present invention reduces both the cost and weight of the final steering wheel assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a side elevation view of a modular steering wheel assembly according to the present invention.

Figure 2 is an exploded, perspective view of a steering column and a hub plate assembly according to the present invention.

Figure 3 is a cross-sectional view of the steering column and hub plate assembly.

Figure 4 is a top plan view of a hub plate assembly and removable tool according to the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

A steering wheel assembly 20 is shown in Figure 1 including a steering wheel 22, an air bag assembly 24, and a hub plate assembly 26. The hub plate assembly 26 is secured to the steering wheel 22 and provides secure attachment between the steering wheel assembly 20 and a shaft 28 of a vehicle steering column 30. A cover 32 is preferably provided encasing the steering column shaft 28 and the hub plate assembly 26. Also, access holes 33 are formed through the cover 32 for a purpose which will be described below. A snap in cover may close access holes 33 when attachment or detachment is not being performed.

As shown in Figure 2 the hub plate assembly 26 comprises a hub plate 34 and a gear 36. The hub plate 34 has an axial bore 38 and a pair of transverse slots 40 and 42, each having a respective inlet end 41 and 43. The gear 36 preferably comprises a helical gear which includes a gear portion 44 and a threaded shaft 46. The threaded shaft 46 extends from a face of the gear portion 44. A plurality of gear teeth 47 are formed at a single straight angle around the periphery of the gear portion 44 of the gear 36. The threaded shaft 46 is disposed in the axial bore 38. The hub plate 34 is secured to a base 25 of the steering wheel 22 by bolts or other attachment structure. There are slots 40, 42 disposed on either side of the axial bore 38 and extend substantially perpendicular to the bore 38. A removable tool 48 includes a worm gear 50 adjacent one end of the tool 48. The worm gear 50 includes at least one spiral thread 51 which is adapted to drive the gear portion 44 and, thus, rotate gear 36 along a longitudinal axis A. The tool 48 is inserted into a slot 40, 42 to drive the gear 36 for attachment or detachment of a steering wheel assembly 20 in a manner described below. A ratchet 53 may be used to rotate the tool 48. A steering column shaft 28 has a threaded bore 52 extending along an axis A which threadably receives the threaded shaft 46 of the gear 36.

As shown m Figure 3 the hub plate 34 includes a collar which defines an axial bore 38. The collar 54 receives the shaft 28 which runs along the longitudinal axis A from a detached position 28a (shown in phantom) . The collar 54 extends from a rear face 55 of the hub plate 34 and the collar 54 engages a tapered outer surface 56 of the shaft 28 to create a wedge lock between the hub plate 34 and steering column shaft 28. The threaded shaft 46 is threadably received m the threaded bore 52. An outer cover 32 (shown in phantom) has a pair of access holes 33 which provide access to the slots 40, 42. Thus, the gear 36 is accessible from outside the cover 32 and steering wheel assembly 20.

In Figure 4 the removable tool 48 is shown driving gear 36. The worm gear 50 is inserted into the slot 40 through an inlet end 41 rearwardly until a tip 64 of the removable tool 48 abuts an opposed end 66 of the slot 40. The end 66 defines a stop for the tool 48. A spiral thread 51 engages teeth 47 of the gear 3b. Rotation of the tool 48 in a counter- clockwise direction (indicated by arrow 68) causes the gear 36 to rotate in a clockwise fashion about an axis A (indicated by arrow 71) . With the threaded shaft 46 received m the threaded bore 52 of the steering column shaft 28, when the tool 48 is actuated countei- clockwise, the gear 36 rotates about the axis A and the threaded shaft 46 is threadably driven into the bore 52 to secure the hub plate 34 to the steering column shaft 28. During this rotation, there is a reaction force between the tool 48 and the gear 36.

The gear and tool are designed such that this reaction force urges the tool 48 further into the hub plate 26. Thus, this reaction force urges the tip 64 against the end 66. The tool 48 is thus firmly held within the hub plate 26. As the resistance to the insertion forces increases, the end 66 prevents the tool 48 from coming out of engagement with the gear 36.

The securement force between the shaft 28 and the hub plate 34 and thus the reaction force to the tool 48 are relatively great. Rotation of the tool 48 in a clockwise fashion in the slot 40 would tend to force the tool 48 out of the slot 40 (to release the shaft 28) and the tip 64 away from the opposed end 66. That is, the reaction force would be in the opposed direction. The tool may, however, be inserted into the slot 42 and rotated counterclockwise (as indicated by arrow 70) to drive the gear 36.

In Figure 4 the tool 48a (shown in phantom) is disposed in the slot 42 with the worm gear 50a in engagement with the gear 36. The tip 64a abuts an opposed end 72 of the slot 42 and counter-clockwise rotation of the tool 48a drives the gear 36 in a counter-clockwise rotation (indicated by arrow 73) about an axis A. The reaction force between the tool 48a and the gear 36 is again toward the opposed end 72. Thus, the tip 64a is held against the opposed end 72. Again, if the tool were rotated in the opposed direction the force would tend to urge the tool outwardly of the slot 42. In a method of assembling a modular steering wheel utilizing the present invention, the tool is moved into a first slot and rotated in a first direction to tighten the gear and secure the hub assembly 20 to a steering column. When it is desired to remove the wheel, the second slot is utilized. The tool is firmly held within the hub plate m either of the attachment or detachment operations. Although the attachment and detachment are illustrated with particular directions of rotation of the tool and gear, and with reference to Figure 4, a worker of ordinary skill in the art would recognize that the opposed rotational directions could achieve similar results . Although the gear has been disclosed having a threaded shaft engaging a threaded bore of the steering column shaft, it should be understood that the gear may have a threaded collar which engages a threaded shaft disposed at the end of the steering column shaft.

Claims

CLAIMS :

1. A hub plate assembly (26) for a steering wheel (22) comprising: a hub plate (34) having an axial bore (38) and a pair of transverse slots (40, 42); and a gear (36) including a gear portion (44) and a threaded shaft (46) extending from said gear portion, said shaft disposed in said bore; wherein a first of said slots provides access to said gear (36) for driving said gear m a first direction, and a second of said slots provides access to said gear for driving said gear in a second direction.

2. A hub plate assembly (26) for a steering wheel (22) as recited in claim 1 wherein said first and second slots (40, 42) each have an inlet end (41, 43) and an opposed end (66, 72), said opposed ends each defining a stop for transferring forces to said gear (36) .

3. A hub plate assembly (26) for a steering wheel (22) as recited in either of claims 1 or 2 wherein said slots (40, 42) are disposed on either

4. A hub plate assembly (26) for a steering wheel (22) as recited in any of the preceding claims further comprising a removable tool (48) which is adapted to rotate in a first direction and cause said gear (36) to rotate clockwise along a longitudinal axis in said first slot and adapted to rotate in said first direction and cause said gear to rotate counterclockwise along said axis in said second slot.

5. A hub plate assembly (26) for a steering wheel (22) as recited in claim 4 wherein said tool is adapted to rotate in a first direction and cause said gear (36) to rotate clockwise along the longitudinal axis in said first slot, and adapted to rotate in said first direction and cause said gear to rotate counter¬ clockwise along said axis in said second slot.

6. A hub plate assembly (26) for a steering wheel (22) as recited in either of claims 4 or 5 wherein said removable tool (48) includes a worm gear (50) .

7. A hub plate assembly (26) for a steering wheel (22) as recited in any of the preceding claims wherein said slots (40, 42) are disposed on either side of said bore (38) .

8. A modular steering wheel assembly comprising: a steering wheel (22); an airbag assembly; and a hub plate assembly (26) for a steering wheel as recited in any of the preceding claims.