GB2124739A

GB2124739A - Improvements in vehicle steering columns

Info

Publication number: GB2124739A
Application number: GB08320770A
Authority: GB
Inventors: Kevin Boyd Humphrey; Ward Richard Cusati
Original assignee: Torrington Co Ltd; Torrington Co
Current assignee: Torrington Co Ltd; Timken US LLC
Priority date: 1982-08-03
Filing date: 1983-08-02
Publication date: 1984-02-22
Also published as: GB8320770D0; FR2531395A1; GB2124739B; FR2531395B1

Abstract

The lower internally splined tubular end section (62) of a steering shaft (60) is received on a splined spigot (76) of a universal joint and is locked in place by means of a spring (68). The end section (72) of the spring (68) is received in a notch (66) in the tubular end section (62) and in an annular groove in the spigot. A hooked end section (71) of the spring (68) is hooked about the shaft end section (62). In another embodiment, a G-shaped spring is received in the notch (66) and encircles the shaft end section and the spigot is inserted after the captively held spring has been fitted, the free end of the spigot being suitably chamfered to provide a lead. <IMAGE>

Description

SPECIFICATION Improvements in vehicle steering columns The present invention relates to steering columns for motor vehicles and more particularly to the steering shaft.

It is customary for one end (hereinafter referred to as the lower end) of the steering shaft for a vehicle steering column to be coupled to the pinion shaft of a rack and pinion mechanism, often via a universal coupling. The steering shaft is generally tubular and its tubular end is provided with internal splines which mesh with external splines of a spigot forming the input part of the universal coupling. To effect a permanent joint it has been customary to groove the lower end of the steering shaft and the spigot and to insert a bolt through the aligned holes, the bolt being secured by means of a nut. Whilst this forms a satisfactory solid joint it is expensive and time consuming to effect.

It is an object of the invention to provide a steering shaft construction which facilitates assembly and in particular which avoids the need for the use of a clamping screw.

The present invention, according to one aspect thereof, resides in a steering shaft for the steering column of a motor vehicle, in which the lower end of the shaft is tubular and is internally of non-circular configuration so as to be received over a complementarily shaped spigot of one part of a universal coupling whose other part is on the input side of a steering mechanism such as a rack and pinion mechanism and in which there is provided a locking mechanism between the shaft lower end and the coupling part such that the two cannot be pulled apart or can be pulled apart only with considerable force, said locking mechanism comprising a peripheral groove in the spigot, a transverse notch in the shaft lower end in register with said groove and a spring secured to the shaft lower end and having a locking section which is received in said notch and in said groove.

In one preferred embodiment, in which the spigot may be inserted in the shaft lower end before the spring is fitted, the spring advantageously includes an extension section which can be hooked around the steering shaft to resiliently hold said locking section in said notch and said groove as well as to hold the spring on the steering shaft.

The present invention, according to another aspect thereof, resides in a steering shaft for the steering column of a motor vehicle, in which the lower end of the shaft is tubular and is internally of non-circular configuration so as to be received over a complementarily shaped spigot of one part of a universal coupling whose other part is on the input side of a steering mechanism, such as a rack and pinion mechanism, and in which there is provided a snap-lock between the shaft lower end and the coupling part such that the two can be pushed together and become locked together such that they cannot be pulled apart, or can be pulled apart only with considerable force.

The snap-lock preferably comprises a spring which at least partially encircles the tubular lower end of the shaft and which has a portion extending through a hole in the tubular lower end to engage a peripheral groove in the universal coupling spigot when the two are snapped together.

The universal coupling spigot preferably has a tapered end to provide'a lead for the spring.

The internal configuration of the lower shaft end can be in the form of serrated teeth or splines but it is also possible to use an oval shape or a polygonal shape. Various combinations of these shapes are also possible.

Normally, the steering column will be of the collapsible type and thus the steering shaft will normally comprise upper and lower parts which are relatively non-rotatable but which are such that one part can be telescoped into the other.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure lisa section on the line I - I of Figure 2 through a steering shaft in accordance with one embodiment of the invention; Figure 2 is a section on the line II - II of Figure 1; Figure 3 is a fragmentary view of the lower end of the steering shaft corresponding to Figure 1 but drawn to a larger scale; Figure 4 is a section on the line IV - IV of Figure 3; Figure 5 is a view similar to Figure 3 but showing the spring in place; Figure 6 is a section on the line VI - VI of Figure 5; Figure 7 is a fragmentary sectional view showing the lower shaft end received on the spigot of a universal joint;; Figures 8 and 9 are cross-sections respectively on the lines VIII - VIII and IX - IX of Figure 2, Figure 70 is an elevation of the lower end of a steering shaft according to another embodiment of the invention, Figure 11 is a fragmentary view of the spigot of the universal joint which is to be attached to the steering shaft, Figure 12 is a section on the line XII - XII of Figure 10,and Figure 13 is a similar section showing the spring unclamped.

Figures 1 and 2 show a steering shaft for a steering column for a motor vehicle. The steering shaft comprises an upper tubular part 10 and a lower tubular part 12. The upper tubular part 10 has a solid projecting end portion 14 having a splined section 16 to receive complementary splines in a steering wheel and a screw-threaded end 18 for receiving a nut which fastens the steering wheel in place. The steering wheel has a tapered portion which wedges on a complementarily shaped section 20 on the steering shaft end 14.

The lower tubular end section 22 of the steering shaft is of somewhat reduced diameter and is provided with internal teeth or splines 24 as indicated more clearly in Figures 4 and 6.

As shown in Figures 3 and 4, the lower shaft end 22 is formed near its extremity with a transverse notch 26 which is deep enough to breakthrough into the interior of the tubular shaft end. As shown in Figures 5 and 6 a G-shaped spring 28 can be snapped into place around the shaft end 22 with an arcuate section 30 of the spring overlying the exterior of the shaft end 22 and with a straight end section 32 of the spring received in the notch 26. The spring 30 is thereby held captive on the shaft end 22 and the spring section 32 protrudes into the interior of the shaft end.

As shown in Figure 7, the shaft end is designed to be received on a spigot 36 which forms the input part of a universal coupling, the remainder of which is not shown. The output part of the universal coupling is fixed to the pinion of a rack and pinion steering mechanism or to the input part of some equivalent steering mechanism. The spigot 36 has external teeth or splines complementary to the internal teeth or splines 24 so that the steering shaft can be pushed on to the spigot. The spigot 36 has a peripheral groove 38 so positioned that the spring section or leg 32 snaps into the groove 38 when the steering shaft has been pushed home. The spigot 36 has at its free end a lead-in taper or bevel 40 to engage the spring leg 32 and thereby enable the end portion of the spigot to force the spring outwardly as the spigot enters the shaft end 22.

During assembly of the motor vehicle, it is simply necessary for the steering shaft to be pressed on to the spigot to effect the joint between the shaft and the universal coupling. There is no subsequent machining and there are no screws to tighten.

Advantages to be gained are that the torque between the steering shaft and the spigot 36 is transmitted entirely by the teeth or splines so that the spring 30 is not placed under any stress.

Accordingly, the torque which the joint is capable of transmitting is totally independent of the spring 30.

Because there is no lead or chamfer at the edges of the annular groove 38 in the spigot it will be difficult to pull the steering shaft off the spigot merely by applying an axial pull.

Apart from the above-mentioned advantages of the snap-lock joint there are the further advantages that it is lighter and cheaper and that there are no loose parts. Any axiai backlash between the steering shaft 22 and spigot 36 will generally be of no consequence. Any angular backlash can be minimised by appropriate dimensioning of the teeth or splines.

As can be seen from Figures 1,2,8 and 9 the steering shaft is of the usual two-part construction as is the case of a collapsible steering column. The upper part 10 is of sufficiently iarge dimensions to receive within it the lower part 12. The steering shaft has an intermediate section of non-circuiar crosssection as can be seen from Figures 8 and 9. Thus, the lower part 12 has what may be described as an oval section 42, the upper end of which is received in an enlarged lower portion 44 of the upper section 10, the portion 44 also being of what might be described as oval cross-section. As specifically illustrated each of these oval cross-sections comprises two arcs joined at their ends by two straight lines.

The upper and lower sections 10 and 12 are attached to one another by a shock absorber 46 which comprises a rubber bushing 48 received between and bonded to outer and inner sleeves 50 and 52. As shown in Figure 9, the outer sleeve 50 is complementarily received with a force fit in the enlarged end 44 of the upper shaft part 10. As shown in Figures 8 and 9, the inner sleeve 52 is slidably received about the enlarged upper end 42 of the lower shaft portion 12. Friction between these parts is increased by means of a spring 54 so that the steering shaft does not collapse during assembly.

The friction however is not so great as to prevent or hinder the shaft from collapsing under accident conditions.

Figure 10 of the drawings shows a lower end of a steering shaft 60 according to another embodiment of the invention for a steering column for a motor vehicle. The steering shaft 60 may comprise upper and lower tubular parts as described with reference to and as illustrated in Figures 1,2,8 and 9. The lower tubular end section 62 of the steering shaft 60 is internally splined as can be seen from Figure 12 and is provided near its extremity with a transverse notch 66 similar to the notch 26 shown in Figures 3 and 4, this notch being deep enough to break into the interior of the tubular shaft end section 62.The shaft end section 62 is designed to be received on a spigot 76 shown also in Figure 11 and forming the input part of a universal coupling whose output part is fixed to the pinion of a rack and pinion steering mechanism orto the input part of an equivalent steering mechanism. As shown in Figure 11, the spigot 76 has external teeth or splines in the shaft end section 62 so that the steering shaft can be pushed onto the spigot as shown in Figure 10. The spigot 76 has a peripheral groove 78 which is so positioned that it registers with the notch 66 when the splined spigot 76 is pushed into the shaft end 62.

After the spigot 76 has been pushed into the shaft end 62, these two parts are locked together by means of a spring 68. The spring 68 has an end section 72 which is received in the notch 66 and in the groove 78, as shown in Figures 10 and 12, and has a clamping section 70 which lies opposite to the end section 72 and fits into a shallow groove 67 formed in the shaft end section 62 approximately diametrically opposite the notch 66. The spring 68 includes a iong leg 69 and a hooked shaped end section 71 which is hooked about the shaft end section 62, as shown in Figures 10 and 12.

The spring 68 has a free state shape as shown in chain-dotted lines at 68a in Figure 10 and as shown in Figure 13.

During assembly of the motor vehicle, the steering shaft 60 is pressed onto the spigot 76 and the spring 68 is pushed into place in the direction of the arrow A of Figure 13 so that the end section 72 is received in the notch 66 in the groove 78 and the section 70 is located in the shallow groove 67 as shown in Figure 13. Thereafter, the leg 68 is swung upwardly and sideways across the shaft end section 62, as shown by the arrow B of Figure 13, and the hooked end section 71 is thereafter hooked about the shaft end section 62, as shown in Figure 12 and in full lines in Figure 10. There is no subsequent machining and there are no screws to tighten.

As with the previous embodiment, the torque between the steering shaft and the spigot is transmitted entirely by the teeth or splines so that the spring 68 is not placed under any additional stress.

The biasing action of the spring 68 on the spigot 76 results in a force in the direction or the arrow C of Figure 10 sufficient to eliminate backlash between the tubular end section 62 and the spigot, resulting in a quiet reliable connection. The half-loop configuration formed by the hooked end-section 71 acts as an easy means for finger assembly of the spring 68 as well as a positive means for securing the spring to the tubular end section. The spring can be easily removed by lifting the hooked end section 61 of the spring up and over the tubular end section 62 of the steering column.

Claims

1. A steering shaftforthe steering column of a motor vehicle, in which the lower end of the shaft is tubular and is internally of non-circular configuration so as to be received over a complementarily shaped spigot of one part of a universal coupling whose other part is on the input side of a steering mechanism, such as a rack and pinion mechanism and in which there is provided a locking mechanismbe- tween the shaft lower end and the coupling part such that the two cannot be pulled apart or can be pulled apart only with considerable force, said locking mechanism comprising a peripheral groove in the spigot, a transverse notch in the shaft lower end in register with said groove and a spring secured to the shaft lower end and having a locking section which is received in said notch and in said groove.

2. A steering shaft as claimed in claim 1, in which the spring includes an extension section which can be hooked around the steering shaft to resiliently hold said locking section in said notch and said groove as well as to hold the spring on the steering shaft.

3. A steering shaft for the steering column of a motor vehicle, in which the lower end of the shaft is tubular and is internally of non-circular configuration so as to be received over a complementarily shaped spigot of one part of a universal coupling whose other part is on the input side of a steering mechanism, such as a rack and pinion mechanism, and in which there is provided a snap-lock between the shaft lower end and the coupling part such that the two can be pushed together and become locked together such that they cannot be pulled apart, or can be pulled apart only with considerable force.

4. A steering shaft as claimed in claim 3, in which the snap-lock comprises a spring which at least partially encircles the tubular lower end of the shaft and which has a portion extending through a hole in the tubular lower end to engage a peripheral groove in the universal coupling spigot when the two are snapped together.

5. A steering shaft as claimed in claim 3 or 4, in which the universal coupling spigot has a tapered end to provide a lead for the spring.

6. A steering shaft as claimed in claim 4 or 5, in which the spring is generally G-shaped.

7. A steering shaft as claimed in any preceding claim, in which the internal configuration of the lower shaft end is in the form of serrated teeth or splines.

8. A steering shaft as claimed in any preceding claim for a steering column of the collapsible type, in which the steering shaft comprises upper and lower parts which are relatively non-rotatable but which are such that one part can be telescoped into the other.

9. A steering shaft for a steering column of a motor vehicle, constructed substantially as herein described with reference to and as illustrated in the accompanying drawings.