WO2005118351A1

WO2005118351A1 - A steering wheel

Info

Publication number: WO2005118351A1
Application number: PCT/SE2005/000536
Authority: WO
Inventors: Michel Moreau
Original assignee: Autoliv Development Ab
Priority date: 2004-06-03
Filing date: 2005-04-14
Publication date: 2005-12-15
Also published as: GB2414717B; GB0412452D0; GB2414717A

Abstract

A steering wheel has a support (12) to be connected to a steering column, and spokes (15) extending from the support to a rim (16). The rim and part of each spoke is covered with a foam (17). An embellishment (18) is mounted on the foam, the embellishment carrying a locator block (24) which defines locator surfaces. An intermediate mounting plate (27) is provided which is adjustably mounted on the support (12). The mounting plate (27) can move in at least two directions. The mounting plate is provided to receive an air-bag housing (34), with depending legs (35) of the air-bag unit being received within apertures (28) of the intermediate support plate. In assembling the steering wheel the steering wheel and support plate are located in an optimum position determined by sensing the position of surfaces of the locator blocks. Subsequently a guide arrangement is moved to a predetermined position in which part of the guide arrangement engages the mounting plate to move the mounting plate to a predetermined position relative to the locator elements and the mounting plate is then secured firmly in position.

Description

"A STEERING WHEEL"

THE PRESENT INVENTION relates to a steering wheel for a vehicle and also relates to a method of manufacturing a steering wheel.

It has been proposed to mount an air-bag in a housing, with the housing itself being mounted in the central part of a steering wheel. In such an arrangement the air-bag housing is typically mounted in a "floating" fashion so that the entire air-bag housing may be depressed slightly to close one or more switches to actuate a hooter.

A steering wheel is typically fabricated by initially preparing a metallic framework forming a support to be connected to a steering column, spokes extending radially outwardly from the support, and a rim carried by the spokes.

A subsequent step in the fabrication process includes applying a foam coating to at least part of the framework.

The application of the foam is not an accurate process, and thus there may be variations in tolerance in the thickness of the foam coating.

Furthermore, it has been found that steering wheels fabricated by this method can suffer from significant inconsistencies as regards the precise location of the metallic framework within the frame coating. Consequently it is difficult to mount an element, such as an air-bag housing, on a steering wheel at precisely the correct position with respect to the foam.

It has been proposed to mount the air-bag housing to the steering wheel through the intermediary of a mounting plate. The mounting plate may be adjustably mounted to the steering wheel, so that there is a predetermined position for the mounting plate in which the air-bag housing, when connected to the mounting plate, is appropriately positioned with regard to the foam. However, it is required for the air-bag housing to have an upper cover substantially flush with the foam layer provided on the spokes of the steering wheel and also for the upper cover of the air-bag to be separated from the foam on each of the spokes by a uniform gap, with the gaps being of equal sizes. Consequently, because the spokes are typically angularly offset from each other, this means that there is a 3-dimensional tolerance chain that has to be considered, so that the air-bag housing is correctly positioned in the x-direction, the y-direction and the z-direction.

If an adjustable mounting plate is used, the mounting plate must initially be located in the correct or optimum position. Any problems of misalignment of the mounting plate will not be discovered until the air-bag housing is mounted on the intermediate mounting plate. If the mounting plate is not in precisely the correct or optimum position, the entire arrangement has to be disassembled, and the position of the plate has to be adjusted relative to the steering wheel before the air-bag housing is re-mounted on the steering wheel. This is time consuming and expensive.

The present invention seeks to provide an improved steering wheel and an improved method of manufacturing a steering wheel. According to one aspect of this of this invention there is provided a steering wheel, the steering wheel incorporating a support to be connected to a steering column, a rim and a plurality of spokes extending from the support to the rim, at least part of at least some of the spokes being provided with a coating, at least some of the spokes being provided with a locator element mounted directly or indirectly to the coating of the spoke, each locator element defining at least one locator surface, the locator surface having a predetermined relationship to the axis of the spoke, the steering wheel further incorporating an adjustable intermediate mounting plate, connected to the support by tightenable fastening elements, the mounting plate being moveable relative to the support when the fastening elements are not tightened, the mounting plate being effectively held firmly in position relative to the support when the fastening elements are tightened, the mounting plate being provided with mounting means to mount an air-bag unit on the mounting plate.

Preferably an air-bag unit is provided, the air-bag unit having depending projections, the mounting means on the mounting plate comprising apertures receiving the projections. Conveniently the steering wheel incorporates three angularly offset radial spokes, each spoke being provided with said coating and with a respective locator element.

Advantageously each locator element defines two locator surfaces, the two locator surfaces being orthogonal.

Preferably each locator element is mounted on an embellishment, the embellishment being mounted on part of the coating provided on the respective spoke, with part of the embellishment being visible in the complete steering wheel.

Conveniently each fastening element is in the form of a threaded element, the threaded element extending from the mounting plate and engaging a threaded bore provided in the said support.

Advantageously a compression spring surrounds part of each threaded element between the intermediate mounting plate and the said support.

Preferably the mounting plate is provided with a plurality of locator apertures.

According to another aspect of this invention there is provided a method of manufacturing a steering wheel, the method comprising the steps of forming a frame incorporating a support, a rim and a plurality of spokes extending from the support to the rim, applying a coating to at least part of some of the spokes, mounting locator elements on the foam provided on at least some of the spokes, each locator element having at least one locator surface providing an intermediate mounting plate, the intermediate mounting plate being connected by tightenable fastening elements to the support, the mounting plate initially being moveable relative to the support when the fastening elements are not tightened, the method further comprising the steps of sensing the position of the locator surface or surfaces of each locator element, and subsequently locating a guide arrangement at a predetermined position relative to the locator surfaces, the guide arrangement incorporating at least one element engaging the mounting plate to move the mounting plate to a predeteπnined position relative to the locator elements, the method further including the step of then tightening the tightenable fastening elements to secure the mounting plate in position. Preferably physical contact sensors are used to sense the position of the or each locator surface, and the method includes the step of locating the steering wheel in an optimum position relative to the sensors, by utilising the sensors to control a mechanism which moves the wheel until the wheel is in the optimum position, the method comprising a further step of retaining the steering wheel in said optimum position and then moving said guide arrangement to a predetermined operative position, the said at least one element of the guide arrangement engaging the mounting plate and consequently moving the mounting plate to a predetermined position relative to the locator elements.

Advantageously the said at least one element provided on the guide arrangement is constituted by two pins, each pin being positioned to engage a corresponding locator aperture provided on the mounting plate to move the mounting plate to a predetermined position.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings in which:

FIGURE 1 is a diagrammatic view of part of a steering wheel provided for explanatory purposes,

FIGURE 2 is a further view similar to that of Figure 1,

FIGURE 3 is an exploded view of the steering wheel in accordance with the invention, FIGURE 4 is an enlarge perspective view of part of the steering wheel of Figure 1, FIGURE 5 is a view of a guide pin and bolt driver assembly, and

FIGURE 6 is a diagrammatic view of an assembly station.

Referring initially to Figure 1 of the accompanying drawings, part of steering wheel is illustrated, the steering wheel having three radially extending angularly offset spokes, each with a foam coating, identified as spokes 1,2,3. The steering wheel has a centrally mounted air-bag housing 4. As shown in Figure 1 a gap 5,6,7 is present between the foam coating of each spoke 1,2,3 and an adjacent part of the air-bag housing 4. The gaps are very uneven, with the gap 5 between the coating of spoke 1 and the air-bag housing 4 being relatively narrow whereas the gap 7 between the coating of spoke 3 and the air- bag housing 4 is relatively broad.

Figure 2 is a view corresponding to Figure 1 showing a further steering wheel of the same general design, but in this embodiment the gaps 5,6,7 are very uneven, with none of the gaps having a uniform width across the whole of its length.

It can be understood that it would be desirable for the air-bag housing to be positioned so that the gaps 5,6,7 are of substantially equal thickness and are uniform throughout their length.

Figure 3 is an exploded view of a steering wheel in accordance with the invention. The steering wheel of Figure 3 is provided with an inner metallic frame 10. The frame 10 comprises a tubular spigot 11 to be connected to the upper end of the steering shaft. The upper end of the spigot 11 is mounted on the underside of a support disc 12, the support disc 12 being provided with a plurality of threaded apertures 13 to receive the threaded shanks of mounting bolts 14.

Extending outwardly and upwardly from the support disc 12 are a plurality of metal spokes 15. Only one spoke is shown, but a typical steering wheel has three radially extending angularly offset spokes, as in the wheel shown in Figure 1. The spokes 15 carry a circular metal rim 16. The radially outermost part of each of the spokes 15 and the rim 16 is provided with a foamed plastics material coating 17 of conventional form.

Mounted on the upper surface of the radially innermost part of the foam coating 17 each spoke 15 is an embellishment 18. The embellishment 18 is shown in more detail in Figure 4. The embellishment 18 is formed, the in the described embodiment, of pressed metal and is in the form of an inverted "U" shaped channel presenting a relatively broad upper face 19 and two depending side walls 20,21. The embellishment is provided with an end wall 22 partially closing the channel. A finger 23 depends from the end wall carrying a locator block 24. The locator block 24 has two orthogonal locator surfaces 25,26. When the spigot 11 is vertical, and the support disc 12 is horizontal the locator surface 25 is horizontal and the locator surface 26 is vertical. The embellishment is mounted on the radially innermost end of the foam coating 17 covering the spoke 15, with the locator block 24 being positioned directed towards the central part of the steering wheel, above the support disc 12.

A similar embellishment 18 is provided on each of the three spokes of the steering wheel. Each locator block 24 thus has a vertical locator surface which is perpendicular to the axis of the respective spoke, and a horizontal locator surface. If the steering wheel is perfectly formed, the horizontal locator surfaces of the three locator blocks 24 should lie in a common plane.

An intermediate mounting plate 27 is provided on the steering wheel. The plate has a form, for example, generally as described in GB 2385834A. The mounting plate 27 is provided with square apertures 28 to receive depending formations, to be described later, provided on an air-bag housing. The depending formations are engaged and retained by a spring on the underside of the plate 27 as described in GB 2385834A. The plate 27 is provided with four round apertures 29 each of which is dimensioned to receive the threaded shank of a bolt 14. Each round aperture 29 has a diameter which is substantially greater than that of the shank of the bolt 14 but which is less than that of the head of the bolt 14. It is thus to be understood that when the bolts loosely pass through the round apertures, the intermediate mounting plate 27 may move, within the plane of the plate, in two orthogonal directions, equivalent to the x-direction and the y-direction. The mounting plate 27 is also provided with two circular guide apertures 30 which are provided at diametrically opposed positions relative to a large central aperture 31. In the described embodiment strong compression springs 32 are provided dimensioned to be received about the threaded shanks of the bolts 14 and to be positioned between the intermediate mounting plate 27, and the support disc 12. It is to be understood, therefore, that the plate 27 may initially be mounted in position, with the threaded shanks of the bolts 14 passing through the round apertures 29, with each shank being surround by a spring 32 and the threaded ends of the shanks 14 being received within the threaded mounting apertures 13 provided in the support disc 12. The plate 27 may be moved within the plane of the plate, thus effecting an adjustment in the x-direction and the y-direction. By tightening the mounting bolts to a desired degree, thus selectively compressing the springs 32, the plate may also be adjusted in the z-direction. Because the springs 32 are strong springs, when the mounting bolts have been tightened to a desired degree, the mounting plate will effectively be held firmly in position.

An air-bag housing 34 is provided, the housing 34 having four downwardly extending projections 35 configured to be received within the square mounting apertures 28 in the intermediate mounting plate 27, and to be retained by the spring, thus allowing the air-bag housing to be connected to the intermediate mounting plate 27. The air-bag housing 34 has an upper cover 36, the upper cover 36 having portions 37 configured and located to lie adjacent the embellishments 18 on each of the spokes. In order to ensure that the intermediate mounting plate 27 is initially located at an appropriate position, so that when the air-bag housing 34 is mounted on the intermediate mounting plate 27 the portions 37 of the upper cover 36 have a desired position relative to the embellishments 18, initially the steering wheel is mounted on a mount, the position of which is adjustable by a controlled motorised arrangement. The wheel is moved so that locator surfaces on the locator blocks 24 provided on the embellishments 18 are brought into contact with sensors. The steering wheel has its position adjusted by the controlled motorised arrangement until the embellishments are in a desired position. Subsequently a guide pin and bolt driver assembly, which will be described, is lowered into a selected position. Guide pins on this assembly engage the locator apertures 30 to cause the intermediate mounting plate 27 to move within its plane to occupy an optimum position relative to the locator blocks 24. This the intermediate mounting plate 27 is positioned appropriately in the x- and y-directions. Subsequently the bolts are tightened, with a desired degree of tightness, so that the intermediate mounting plate 27 is secured in position, and also an appropriate position in the z-direction.

Figure 5 illustrates a guide pin and bolt driver assembly 40. The assembly includes a horizontal support plate 41. Depending from the underside of the support plate 41 are two guide pins 42,43 each guide pin have a pointed lower end. The diameter of each guide pin is very slightly less than the diameter of each of the locator apertures 30 present in the intermediate plate 27. Also mounting on the plate 41 are four spaced apart vertical bolt drivers 44. Each bolt driver 44 comprises a housing 45 of cylindrical form, containing a drive motor. Depending from the lower end of each housing is a drive shaft 46, the drive shaft terminating with a chuck 47. The chuck 47 is dimensioned to engage the head of a bolt.

Turning now to Figure 6, an assembly station 50 includes a lower housing containing a controlled motorised arrangement 51, which has a support shaft 52 emerging from its upper surface. The motorised arrangement may include electric motors, or hydraulic motors, such as piston and cylinder motor units. The support shaft 52 is dimensioned to be received within the tubular spigot 11 provided on a steering wheel so that a steering wheel, such as the steering wheel 53, may be located on the controlled motorised arrangement. The controlled motorised arrangement is configured so that the shaft 52 may be moved vertically upwardly and downwardly, in the "z" direction and may also be moved into orthogonal directions in horizontal plane, thus moving in the "x" and "y" directions. Thus the controlled motorised arrangement may move the steering wheel in the x, y or z direction. When the steering wheel is mounted in position on the controlled motorised arrangement 51, the intermediate mounting plate 27 is positioned above the support disc 12, with the bolts 14 in position and loosely threaded into the bores 13. A rigid support structure 54 is provided located adjacent the controlled motorised arrangement 51. Mounted on the support 54 is a sensor unit 55. The sensor unit 55 is movably mounted on the support 54, but may initially be moved to a precisely predetermined position above the steering wheel. The sensor unit 55 is provided with three depending probe arms 56. Each probe arm 56 is provided with two ball sensors 57,58. The ball sensors are physical contact sensors. The ball sensors are mounted, on the depending arms 56, so that the two ball sensors 57,58 on each arm 56 may be brought into contact with, respectively, the horizontal locator surface 25 and the vertical locator 26 on a locator block provided on an embellishment 18 as provided on one of the three spokes of a steering wheel 53.

It is to be appreciated, therefore, that once the steering wheel has been located in position on the controlled motorised arrangement 51, the sensor unit 55 is moved to the predetermined position immediately adjacent the steering wheel. The controlled motorised arrangement is then actuated, and is controlled by control signals from the sensor arrangement, until the locator surfaces 25,26 on the three locator blocks 24 are in optimum positions. The sensor unit 55 is then moved away from the operative position. The steering wheel has thus now been located with the locator blocks, and thus the embellishments 18, in an optimum position relative to the support 54.

Subsequently a guide pin and bolt drive assembly 40, of the type described above, which is mounted on the support 54, is lowered, towards an operative position which is again a position which is fixed or predetermined relative to the support. The operative position thus has a specific or optimised positional relationship relative to the sensor blocks.

As the guide pin and bolt drive assembly 40 is lowered initially, the guide pins 42,43, which have pointed lower ends, become inserted in the locator apertures 30 provided in the intermediate mounting plate 27. As the pins 42,43 are lowered further, because of the tapering lower ends of the pins, the intermediate mounting plate 27 will move within its horizontal plane, to have a precisely predetermined position with each guide pin 42,43 centred in a respective locator aperture 30.

The bolt drivers then engage the four bolts which pass through the round apertures in the intermediate mounting plate 27 and which are initially loosely threaded into the threaded bores 13. The bolts are tightened so that the heads of the bolts lie in precisely predetermined positions relative to the support plate 41 of the guide pin and bolt driver assembly. The plate 41 is held, at this phase of the operation, in the precisely predetermined operative position. Consequently, by tightening the bolts appropriately, each bolt head has a precisely predetermined position relative to the locator blocks 24, and the springs 32 between the intermediate mounting plate 27 and the support disc 12 become compressed. The intermediate mounting plate 27 is then in a precisely predetermined desired position relative to the locator blocks 24, in the x, y and z directions.

The steering wheel is then removed from the assembly station shown in Figure 6 and an air-bag housing 34 is connected to the intermediate mounting plate. It should then be found that the upper cover 36 of the air-bag housing is positioned so that the portions 37 of the upper cover have an appropriate spatial relationship with the adjacent embellishment 18 on each of the spokes of the steering wheel.

The invention has been described with reference to the use of a specific form of locator blocks. In modified embodiments the locator blocks can be secured to or moulded integrally with the foam coating. Each locator block must define at least one surface, the position of which can be sensed. There should be a sufficient number of locator blocks to enable the steering wheel to be moved to an optimum position. While the described embodiment uses physical contact sensors, such as bore sensors, to determine the position of the locator surfaces, in an alternative embodiment optical sensors, such as laser sensors, could be used.

In a simplified embodiment of the invention the position of the intermediate mounting plate is only adjusted in the x and y directions.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

Claims

CLAIMS:

1. A steering wheel, the steering wheel incorporating a support (11) to be connected to a steering column, a rim and a plurality of spokes (15) extending from the support to the rim (16), at least part of at least some of the spokes being provided with a coating (17), characterised in that at least some of the spokes being provided with a locator element (24) mounted directly or indirectly to the coating of the spoke, each locator element (24)defining at least one locator surface (25,26), the locator surface having a predetermined relationship to the axis of the spoke, the steering wheel further incorporating an adjustable intermediate mounting plate (27), connected to the support by tightenable fastening elements (14), the mounting plate being moveable relative to the support when the fastening elements are not tightened, the mounting plate being effectively held firmly in position relative to the support when the fastening elements are tightened, the mounting plate being provided with mounting means (28) to mount an air-bag unit on the mounting plate.

2. A steering wheel according to Claim 1 wherein an air-bag unit (34) is provided, the air-bag unit having depending projections (35), the mounting means on the mounting plate comprising apertures (28) receiving the projections.

3. A steering wheel according to Claim 1 of Claim 2 wherein the steering wheel incorporates three angularly offset radial spokes (15), each spoke being provided with said coating (17) and with a respective locator element (24).

4. A steering wheel according to any one of the preceding Claims wherein each locator element (24) defines two locator surfaces (25,26), the two locator surfaces being orthogonal.

5. A steering wheel according to any one of the preceding Claims wherein each locator element (24) is mounted on an embellishment (18), the embellishment being mounted on part of the coating (17) provided on the respective spoke (15), with part of the embellishment being visible in the complete steering wheel.

6. A steering wheel according to any one of the preceding Claims wherein each fastening element (14) is in the form of a threaded element, the threaded element extending from the mounting plate (27) and engaging a threaded bore provided in the said support (11).

7. A steering wheel according to Claim 6 wherein a compression spring (32) surrounds part of each threaded element (14) between the intermediate mounting plate (27) and the said support (11).

8. A steering wheel according to any one of the preceding Claims wherein the mounting plate is provided with a plurality of locator apertures.

9. A steering wheel, the steering wheel incorporating a support (11) to be connected to a steering column, a rim and a plurality of spokes (15) extending from the support to the rim (16), at least part of at least some of the spokes being provided with a coating (17), characterised in that at least some of the spokes being provided with a locator element (24) mounted directly or indirectly to the coating of the spoke, each locator element (24)defining at least one locator surface (25,26), the locator surface having a predetermined relationship to the axis of the spoke, the steering wheel further incorporating an adjustable intermediate mounting plate (27), connected to the support by tightenable fastening elements (14), the mounting plate being moveable relative to the support when the fastening elements are not tightened, the mounting plate being effectively held firmly in position relative to the support when the fastening elements are tightened, the mounting plate being provided with mounting means (28) to mount an air-bag unit on the mounting plate wherein an air-bag unit (34) is provided, the air-bag unit having depending projections (35), the mounting means on the mounting plate comprising apertures (28) receiving the projections, and wherein each locator element (24) defines two locator surfaces (25,26), the two locator surfaces being orthogonal, and wherein each locator element (24) is mounted on an embellishment (18), the embellishment being mounted on part of the coating (17) provided on the respective spoke (15), with part of the embellishment being visible in the complete steering wheel.

10. A method of manufacturing a steering wheel, the method comprising the steps of forming a frame incorporating a support (11), a rim (16) and a plurality of spokes (15) extending from the support to the rim, and applying a coating (17) to at least part of some of the spokes, characterised in that the method further comprises mounting locator elements (24) on the foam provided on at least some of the spokes, each locator element having at least one locator surface (25,26), providing an intermediate mounting plate (24), the intermediate mounting plate being connected by tightenable fastening elements (14) to the support (11), the mounting plate initially being moveable relative to the support when the fastening elements are not tightened, the method further comprising the steps of sensing the position of the locator surface or surfaces of each locator element, and subsequently locating a guide arrangement (40) at a predetermined position relative to the locator surfaces, the guide arrangement incorporating at least one element (42,43) engaging the mounting plate to move the mounting plate to a predetermined position relative to the locator elements, the method further including the step of then tightening the tightenable fastening elements to secure the mounting plate in position.

11. A method according to Claim 10 wherein physical contact sensors (58) are used to sense the position of the or each locator surface, and the method includes the step of locating the steering wheel in an optimum position relative to the sensors, by utilising the sensors to control a mechanism (51) which moves the wheel until the wheel is in the optimum position, the method comprising a further step of retaining the steering wheel in said optimum position and then moving said guide arrangement (40) to a predetermined operative position, the said at least one element (42,43) of the guide arrangement engaging the mounting plate (27) and consequently moving the mounting plate (27) to a predetermined position relative to the locator elements (24).

12. A method according to Claim 11 or 12 wherein the said at least one element provided on the guide arrangement is constituted by two pins (42,43), each pin being positioned to engage a corresponding locator aperture (30) provided on the mounting plate to move the mounting plate to a predetermined position.

13. A method of manufacturing a steering wheel, the method comprising the steps of forming a frame incoφorating a support (11), a rim (16) and a plurality of spokes (15) extending from the support to the rim, and applying a coating (17) to at least part of some of the spokes, characterised in that the method further comprises mounting locator elements (24) on the foam provided on at least some of the spokes, each locator element having at least one locator surface (25,26), providing an intermediate mounting plate (24), the intermediate mounting plate being connected by tightenable fastening elements (14) to the support (11), the mounting plate initially being moveable relative to the support when the fastening elements are not tightened, the method further comprising the steps of sensing the position of the locator surface or surfaces of each locator element, and subsequently locating a guide arrangement (40) at a predetermined position relative to the locator surfaces, the guide arrangement incoφorating at least one element (42,43) engaging the mounting plate to move the mounting plate to a predetermined position relative to the locator elements, the method further including the step of then tightening the tightenable fastening elements to secure the mounting plate in position, wherein physical contact sensors (58) are used to sense the position of the or each locator surface, and the method includes the step of locating the steering wheel in an optimum position relative to the sensors, by utilising the sensors to control a mechanism (51) which moves the wheel until the wheel is in the optimum position, the method comprising a further step of retaining the steering wheel in said optimum position and then moving said guide arrangement (40) to a predetermined operative position, the said at least one element (42,43) of the guide arrangement engaging the mounting plate (27) and consequently moving the mounting plate (27) to a predetermined position relative to the locator elements (24), and wherein the said at least one element provided on the guide arrangement is constituted by two pins (42,43), each pin being positioned to engage a corresponding locator aperture (30) provided on the mounting plate to move the mounting plate to a predetermined position.