GB2431980A

GB2431980A - A steering column shaft support housing formed by joining two concave segments

Info

Publication number: GB2431980A
Application number: GB0521057A
Authority: GB
Inventors: Laurie Barton; Jim Bentley
Original assignee: NSK Steering Systems Europe Ltd
Current assignee: NSK Steering Systems Europe Ltd
Priority date: 2005-10-17
Filing date: 2005-10-17
Publication date: 2007-05-09
Anticipated expiration: 2025-10-17
Also published as: GB0521057D0; GB2431980B

Abstract

A steering shaft support housing 100 has a bearing housing portion 126, 128 and a support portion 118,120. The support portion has side walls with attachment protrusions or recesses 122, 124 for attachment to a steering column position adjustment mechanism. The housing has joint lines 134 joining two cooperating concave segments, for example by welding. Forming the housing this way allows the concave segments to be formed by pressing and subsequent joining, so that a finished piece of complex shape can be produced. Transverse ribs stiffen the housing for resisting clamping loads. The joint could also be formed with adhesive or braising.

Description

STEERING APPARATUS AND THOD FOR ITS MANUFACTURE

The present invention relates to steering apparatus, typically for automobiles such as cars, and methods for manufacture of such steering apparatus.

Steering columns in modern cars are carefully designed in order to provide various operational functions. Many known steering columns allow the driver to adjust the position of the steering wheel by unclamping an adjustment mechanism, moving the steering column to desired position, and re-clamping the adjustment mechanism. Some steering columns allow the adjustment of both the rake (i.e. angle) of the steering wheel as well as the reach of the steering wheel.

Furthermore, some steering columns are additionally provided with energy absorbing mechanisms to allow for controlled, energy- absorbing collapse of the steering mechanism in a crash condition.

An example of part of a modern steering column assembly 10 for a car is illustrated in GB-A-2403692 and in Fig. 1. A main bracket 16 attaches to a cross beam (not shown) of the car (not shown) . Thus, the main bracket 16 is substantially fixed in position. Depending from main bracket 16 is an adjustable clamping mechanism 20, fixed to a sliding bracket 13. Clamping bolt 28 can be loosened by rotation of lever 22, allowing adjustment of the position of the steering wheel (not shown) in the reach (X) and rake (Y) directions.

In the following discussion, the "forward" end of the assembly is taken to be in the "forward" direction of the car (i.e. towards the front wheels) and the "rearward" end of the assembly is taken to be in the "rearward" direction of the car (i.e. towards the steering wheel) An upper steering shaft 11 is attached at its front end to a mechanism (not shown) for directing the front wheels (not shown) of the car in a known manner. The rear end 15 of the upper steering shaft 11 is attached to a steering wheel (not shown) The upper steering shaft 11 is retained at its forward end by forward bearing housing 30 and at its rearward end by rearward bearing housing 12. Rearward bearing housing 12 has a substantially cylindrical internal cross section, in view of the need to provide rotational bearing of the upper steering shaft 11.

Rearward bearing housing 12 is received within and welded to support housing 14, providing flat side walls 19 having attachment locations 32 for attachment of a series of reach adjustment slotted clutch plates 34 interleaved with a series of rake adjustment slotted clutch plates and the clamping bolt in the way described in GB-A-2403692.

The assembly shown in Fig. 1 is capable of ride-down in a crash condition, the sliding bracket 13 moving forwardly relative to the main bracket 16 along slot 18 in the way described in GB-A-2403692.

The combination of the rearward bearing housing and the support housing has a complex shape, in view of the need to provide a rotational bearing for the steering shaft and to provide various recesses, cut-outs and protrusions that are required to locate the support housing with respect to the adjustment mechanism. In GB-A-2403692, the support housing is formed from various pressed sheet metal parts that are subsequently bolted and welded together.

The present invention has been devised in view of the complex nature of the formation of support housings and shaft bearings for steering column assemblies. Preferably, the present invention addresses this problem by providing a relatively simple forming operation.

In a first aspect, the present invention provides a steering shaft support housing having: a bearing housing portion for housing a rotational bearing assembly for a steering shaft to be located along a steering shaft axis, a support portion having side walls with attachment protrusions and/or attachment recesses for attachment to a steering column position adjustment mechanism, and at least one joint line extending along the length of the steering shaft support housing, substantially aligned with the steering shaft axis, wherein the joint line joins two cooperating concave segments and the bearing housing portion is provided by the co-operation of respective first regions of said cooperating concave segments and the support portion is provided by the co-operation of respective second regions of said cooperating concave segments, and, for each concave segment, said first region and said second region are formed integrally.

Using the invention, it is possible to form the steering shaft support housing by joining two pre-formed segments.

The resultant steering shaft support housing therefore has the bearing housing portion fixed with respect to the support portion at least in part by an integral link, provided due to the first and second regions of each respective segment being formed integrally.

The pre-forming of the segments may conveniently be carried out by casting or pressing. It is not usually possible to form the entire steering shaft support housing in one piece by conventional casting or pressing techniques, since the overall shape of the steering shaft support housing is not conducive to such techniques. High volume casting or pressing usually requires that two mould pieces or die pieces are brought together to define between them the required final shape for the workpiece. The mould pieces or die pieces are then brought apart to eject the formed workpiece. However, a non-symmetrical enclosed shape does not permit the formation of such a shape by such a technique.

Alternative forming techniques are conceivable for forming a steering shaft support housing. One such technique is hydroforming, in which a tubular blank can be formed into a desired shape by placing the blank in a suitably shaped die and applying fluid pressure to the inside of the blank to force it to conform to the shape of the die. Hydroforming allows the formation of very complex shapes, such as a steering shaft support housing. However, such technology requires very high capital expenditure. The formation of a steering shaft support housing without joining segments is not within the scope of this invention. Instead, the present invention is intended to encompass alternative ways of forming steering shaft support housing having similar overall final shapes.

In a second aspect, the present invention provides a method for forming a steering shaft support housing having: a bearing housing portion for housing a rotational bearing assembly for a steering shaft to be located along a steering shaft axis, and a support portion having side walls with attachment protrusions and/or attachment recesses for attachment to a steering column position adjustment mechanism, the method including the steps: forming at least two concave segments for cooperating to form the steering shaft support housing, and joining the concave segments along a joint line extending along the length of the steering shaft support housing, substantially aligned with the steering shaft axis, so that the bearing housing portion is provided by the co-operation of respective first regions of said cooperating concave segments and the support portion is provided by the co-operation of respective second regions of said cooperating concave segments, and, for each concave segment, said first region and said second region are formed integrally.

In a third aspect, the present invention provides a steering column assembly including a steering shaft support housing according to the first aspect and a main bracket for mounting on a vehicle, a steering shaft and a steering column adjustment mechanism for adjusting the position of the steering shaft and the steering shaft support housing with respect to the main bracket.

The steering column assembly may also include a sliding bracket attaching between the steering shaft support housing and the main bracket, the sliding bracket being mounted to move relative to the main bracket in a crash condition in order to absorb energy.

Preferred and/or optional features of the invention are set out below. Unless the context demands otherwise, these are applicable to any aspect of the invention, and may be applied singly or in any combination to any such aspect, Typically, the steering shaft support housing is formed from only two cooperating concave segments. These may substantially be mirror-images of each other. In the case of only two such segments, there will be two joint lines, in order to firmly attach the segments to each other. In this case, the joint lines will usually be on opposing sides of the housing, e.g. disposed on opposite lateral sides of the housing or disposed on upper and lower sides of the housing.

Generally, the joint lines and the steering shaft axis will be substantially coplanar.

It is possible to form the steering shaft support housing using more than two cooperating segments. This might be desirable in the case where the internal and/or external shape of the steering shaft support housing is particularly complex. Typically, of course, the number of joint lines will be equal to the number of such segments.

The overall shape of the segments is usually concave (at least to some extent) in order to journal the steering shaft and to provide joining surfaces on each segment for joining to opposing joining surfaces of adjacent segments.

Preferably, the segments are formed by pressing, e.g., metal sheet. However, the segments may be formed by casting. In either case, additional machining may be carried out in order to form features requiring precise geometry, e.g. tapped screw holes. With conventional pressing and casting, one limitation of the shape of the formed segment is that the die pieces or mould pieces must be capable of being drawn away from the formed segment in order to eject that formed segment. Such a limitation does not apply to complex casting techniques such as investment casting, but it will be understood that such casting techniques are not usually economically viable for a component such as a steering shaft support housing.

Preferably, the segments are joined by welding. After welding, the welded joint line may be machined, ground or polished in order to provide a uniform outer surface to the steering shaft support housing.

Preferably, the steering shaft support housing provides a through-conduit for the steering shaft. The bearing housing portion is preferably disposed at a rearward end of the steering shaft support housing. The support portion is preferably disposed towards a forward end of the steering shaft support housing. Here, "forward" and "rearward" are intended to specify the relative spatial relationships between the bearing housing portion and the support portion.

These directions may also relate to the intended location of the steering shaft support housing in a vehicle.

The steering shaft support housing may include one or more through-holes provided off-axis (e.g. perpendicular) to the steering shaft axis. These through-holes may be for the attachment of other components to the steering shaft support housing, e.g. bolts, brackets and an adjustment mechanism for adjusting the position of a steering wheel relative to a driver of the vehicle.

The steering shaft support housing may include one or more inwardly directed protrusions from an internal surface of the housing. Such protrusions may be of use, for example in retaining other components to the housing, such as the steering shaft bearings to be retained in the bearing housing portion.

Preferred embodiments of the invention will now be described, with reference to the drawings, in which: Fig. 1 shows a known steering column assembly according to GB-A-2403692 Fig. 2 shows a forward topside perspective view of a steering shaft support housing according to an embodiment of the invention Fig. 3 shows a rearward underside perspective view of the steering shaft support housing Fig. 1 has been discussed already and is not discussed further here. It is understood that the skilled person will easily be able to adapt the assembly of Fig. 1 to replace the steering shaft support housing 12,14 of GB-A-2403692 with a steering shaft support housing according to the present invention, in the light of the present disclosure.

Fig. 2 shows one perspective view of a steering shaft support housing 100 according to an embodiment of the present invention. Fig. 3 shows an alternate perspective view of the same steering shaft support housing 100, so uses similar reference numerals to those used in Fig. 2.

Finished housing 100 has a relatively complex shape, in view of the various tasks it must be capable of performing in use. Attachment holes 102, 104, 106, 108 are provided to attach a series of slotted reach adjustment clutch plates (not shown in Figs. 2 and 3 but shown as plates 34 in Fig. 1) to the housing 100. AThen assembled in the finished steering apparatus, these reach adjustment clutch plates interleave with a series of slotted rake adjustment clutch plates in order to provide resistance to movement of the steering wheel position when clamped in position. Slots 110, 112 are provided through the housing 100 in order to coincide with the slots of the slotted reach adjustment clutch plates, to allow the clamping bolt of the clamping mechanism (not shown in Figs. 2 and 3 but shown as 28 and 20 respectively in Fig. 1) to extend transversely through the housing and to move with respect to the housing, e.g. when the reach position of the steering wheel is being adjusted.

Transverse grooves 114, 116 are provided at the underside of the housing 100, extending across the housing. These transverse grooves 114, 116 act as stiffening ribs to reduce the risk of buckling or crushing of the housing 100 under the clamping loads of the clamping bolt.

At is forward end, housing 100 has two forwardly extending arms 118, 120. Each of these arms is provided with a slot 122, 124, each slot extending longitudinally along its respective arm 118, 120. In the finished assembly, pivot liners (not shown) are retained in slots 122, 124. Slots 122, 124 allow limited movement of housing 100 for rake and reach adjustment. In this way, a pivot axis for rake adjustment passes through slot 122, 124 irrespective of the reach position of the housing 100. This arrangement is different to that shown in Fig. 1, where the pivot axis passes through the forward bearing housing 30.

At its rearward end, housing 100 has a cylindrical portion 126, 128 with an open end 129 for receiving a steering shaft (not shown) and a steering shaft rearward bearing (not shown) . Cylindrical portion 126, 128 is provided with internal lugs 130 for retaining the steering shaft rearward bearing. Forwardly of internal lugs 130 is slot 132 for receiving a steering lock bolt (not shown) which is engageable with a lock collar (not shown) on the steering shaft in order to lockably prevent rotation of said steering shaft.

As is clear from Figs. 2 and 3, it would be difficult to form the steering shaft support housing 100 in a single conventional pressing step, since many of the shape features of the housing 100 are would require pressing operations in directions that would not allow the workpiece to be inserted into, or ejected from, the press. It may be possible to form the housing 100 via casting, but intricate details or shapes requiring small tolerances (e.g. screw holes) must usually be machined into the as-cast product.

Instead, the steering shaft support housing 100 is formed by a two-stage process. Housing 100 is formed initially in two halves, longitudinal concave segment A and longitudinal concave segment B. The halves are formed by known pressing techniques. The skilled person will understand, on an examination of Figs. 2 and 3 that halves A and B can be formed in a straightforward manner by pressing, since the various shape features of each half would not impede the insertion or ejection of the workpiece from a suitable press. For example, the skilled person will understand that the formation of transverse grooves 114, 116 by pressing will lead to the formation of corresponding transverse ridges 115, 117 at the internal surface of the housing, and that the formation of lugs 132 by pressing requires the formation of indents 131 in the outer surface of the housing.

After forming the two halves A and B, they are joined together by welding along lines 134, 136. Suitable welding methods for this task will be well known to the skilled person so are not repeated here. If necessary, the weld bead may be finished by suitable machining or grinding.

Alternative jointing methods may be used, such as adhesive or brazing, as required.

The resultant housing 100 has various advantages over known steering shaft support housings. The use of pressed parts that cooperate by face-to-face abutment (i.e. only abut along a face corresponding to the thickness of the pressed parts) allows the weight of the housing to be reduced, since overlapping portions are avoided. Furthermore, the use of pressed parts allows the manufacturing process of the housing to be simpler than a process requiring casting and subsequent further fabrication steps such as machining.

On reading this disclosure, the skilled person will understand that modifications to the illustrated embodiment, further embodiments and modifications thereof can be made, and as such, those modifications, further embodiments and modifications thereof are within the scope of the present invention.

Claims

CLAIMS

1. A steering shaft support housing having: a bearing housing portion for housing a rotational bearing assembly for a steering shaft to be located along a steering shaft axis, a support portion having side walls with attachment protrusions and/or attachment recesses for attachment to a steering column position adjustment mechanism, and at least one joint line extending along the length of the steering shaft support housing, substantially aligned with the steering shaft axis, wherein the joint line joins two cooperating concave segments and the bearing housing portion is provided by the co-operation of respective first regions of said cooperating concave segments and the support portion is provided by the co-operation of respective second regions of said cooperating concave segments, and, for each concave segment, said first region and said second region are formed integrally.

2. A steering shaft support housing according to claim 1 having two joint lines joining the two cooperating concave segments to each other, said joint lines being disposed on opposing sides of the housing.

3. A steering shaft support housing according to claim 1 or claim 2 wherein joint lines and the steering shaft axis are substantially coplanar.

4. A steering shaft support housing according to any one of claims 1 to 3 wherein the concave segments are formed by pressing metal sheet.

5. A steering shaft support housing according to any one of claims 1 to 4 wherein the segments are joined by welding.

6. A steering shaft support housing according to any one of claims 1 to 5, further having one or more through-holes provided off-axis to the steering shaft axis.

7. A steering shaft support housing according to any one of claims 1 to 5 having an internal surface, that internal surface including one or more inwardly directed protrusions.

8. A method for forming a steering shaft support housing having: a bearing housing portion for housing a rotational bearing assembly for a steering shaft to be located along a steering shaft axis, and a support portion having side walls with attachment protrusions and/or attachment recesses for attachment to a steering column position adjustment mechanism, the method including the steps: forming at least two concave segments for cooperating to form the steering shaft support housing, and joining the concave segments along a joint line extending along the length of the steering shaft support housing, substantially aligned with the steering shaft axis, so that the bearing housing portion is provided by the co-operation of respective first regions of said cooperating concave segments and the support portion is provided by the co-operation of respective second regions of said cooperating concave segments, and, for each concave segment, said first region and said second region are formed integrally.

9. A method according to claim 8 wherein the pre-forming of the concave segments is carried out by pressing.

10. A method according to claim 8 or claim 9 wherein the segments are joined by welding.

11. A steering column assembly including a steering shaft support housing according to any one of claims 1 to 7 and a main bracket for mounting on a vehicle, a steering shaft and a steering column adjustment mechanism for adjusting the position of the steering shaft and the steering shaft support housing with respect to the main bracket.

12. A steering column assembly according to claim 11 further including a sliding bracket attaching between the steering shaft support housing and the main bracket, the sliding bracket being mounted to move relative to the main bracket in a crash condition in order to absorb energy.