ADJUSTABLE STEERING COLUMN

Abstract: A clamping mechanism for an adjustable steering column for a vehicle in which antifriction elements (1) are provided which interpose between relatively sliding components (2, 3) of an adjustable steering column construction (20) each element allows sliding between limiting stops with resilient means (10) between the stops to provide a soft stop. The resilient means may be a separate member or resilient portions (10) at the ends of a slot (4) in the element. Walls of the element may have longitudinal slits to take up manufacturing tolerance.

Description: ADJUSTABLE STEERING COLUMN This invention relates to a clamping mechanism for use between relatively sliding components of an adjustable steering column construction for a vehicle. It is known from our present PCT Application No. PCT/GB94/01431 to provide a clamping mechanism with an antifriction element which allows for a dual purpose slotted liner which allows low friction plastics contact for adjustment and high friction metal contact for positive locking of the mechanism. This improves the "feel" to the user. According to one aspect of the present invention, there is provided an antifriction element for use between relatively sliding components in a clamping mechanism of an adjustable steering column construction for a vehicle, the element being locatable between two said components wherein in an undamped state of the components, a part of the element acts to urge the components away from contact with one another to allow relative free sliding of the components on the element and in a clamped state of the components said part is deflecred to allow direct contact between surfaces of the components to provide the clamping friction and wherein the antifriction element allows sliding between limiting stops characterised in that a resilient means is provided between said stops. The resilient means may be either a separate member inserted into a slot in the antifriction element or else resilient ends to a slot in the antifriction elements. The resilient ends may be formed as resilient inserts at the slot ends. The provision of the resilient means enables a steering column to be adjusted so that as it reaches the limiting stops of its adjustment it is stopped softly. According to another aspect of the invention there is provided a steering column comprising a first clamp member, a second clamp member slidable relative to the first clamp member, the first clamp member and second clamp member being in contact with one another when the steering column is in a clamped state; and an antifriction element as defined hereinbefore interposed between the first clamp member and the second clamp member. For a better understanding of the invention and to show how the same may be carried out to effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Fig. 1 is a perspective view of an antifriction element according to the invention for use between relatively sliding components of an adjustable steering column construction for a vehicle, Fig. 2 is a cross section of the antifriction of Fig. 1 located diagrammatically between two such sliding components in an undamped position, Fig. 3 in similar cross section to Fig. 2 but showing the clamped condition, Fig. 4 is a side view, partly in section, which shows an adjustable steering column construction incorporating two of the antifriction elements of Fig. 1, one for linear adjustment of the column and the other for vertical adjustment of the column, Fig. 5 is an end view in section of the construction of Fig. 4 using the antifriction element of Fig. 1, Fig. 6 is an exploded perspective view of a construction similar to that of Fig. 4 using the antifriction element of Fig. 1, Fig. 7 is an exploded perspective view similar to Fig. 6 but with an antifriction element according to a second embodiment of the invention, Fig. 8 is a perspective view of a vertical antifriction element according to the first embodiment of the invention shown in Fig. 1 and used in the Fig. 6 construction, Fig. 9 is a perspective view of a linear antifriction element according to the first embodiment of the invention shown in Fig. 1 and used in the Fig. 6 construction. Fig. 10 is a perspective view of one of the antifriction elements antifriction elements according to the second embodiment used in the construction of Fig. 7, Figs. 11 and 12 are perspective views of vertical and linear antifriction elements according to a third embodiment of the invention similar to those shown in Fig.s 8 and 9 for the construction of Fig. 6, Fig. 13 is a cross section taken on of Fig. 12, and Fig. 14 is a cross section taken on YY of Fig. 12. In Fig. 1 there is shown diagrammatically an antifriction element in the form of a slotted flanged plastics liner 1 for interposition between two relatively sliding components 2,3 respectively of an adjustable steering column construction 20, as shown in Fig. 4 The liner 1 has a longitudinal slot 4 providing limiting stops through which an adjustment bar 5 of an adjustment mechanism extends. The adjustment mechanism includes a clamp handle 6 which when moved to the broken line position of Fig. 4 tightens part 2 and 3 together. The liner 1 has two opposing flanges 7 extending in the liners undamped state (Fig. 2) at an angle from the plane of a surface 8 of the liner. When the adjustment mechanism is tightened by the clamp handle to the position shown in Fig. 3 the liner assists to increase the clamping action. Liner's 1 are normally provided in pairs that is a vertical liner IV and a linear liner IL (see Fig. 4) . All this is as described in our PCT Application No. PCT/GB94/01431 hereafter referred to as "PCT application", the subject matter of which is incorporated herein by reference. A first improvement over the liners of the PCT application is to provide a soft resilient block 10 of an elastomeric material either plastics or rubber at each end of slot 4. This is shown in detail in Fig. 8 which is a vertical liner IV and Fig. 9 which in a linear liner IL. The provision of blocks 10 cushions the impact of bolt 5 on the liner as the column stops at the end of the vertical and/or linear throw. In Fig. 6 which incorporates the liners of Figs. 8 and 9 rubber sleeves 11 are provided to fit around bolt 5 and to slide in the liner slots 4. A second embodiment is to provide cushioning by means of an antifriction element formed as a stop member. This is shown in Fig. 10 at 30 and in Fig. 7 where there are four such stop members which fit into and slit within slots 4 in antifriction elements IV and IL' which are similar to those shown in Figs. 8 & 9 but without cushioning blocks 10. The cushioning between the stop numbers and the antifriction elements is by means of the stop members 30 being formed as rubber moulded parts wither solid rubber or rubber moulded over a metal form so that the ends 31 of the stop members have buffer portions 31. Also the stop members have internal ribs 32 within a hole 33 in a central boss 34 through which bolt 5 passes. The internal ribs act to prevent rattle. These are seen in Fig. 10. A third improvement may be seen in vertical and linear antifriction elements IV" and IL" shown in Figs. 11 to 14. In the liner elements shown in Figs. 11 to 14 longitudinal walls 40 either side of longitudinal slots 4" have their surfaces 42 provided with a slit 44 extending along most of the length of the slots 4". Fig. 14 shows the slit 44 open and in the uncompressed state before fitting into retaining slots 46 in clamping mechanism brackets 48 and 50 of either mechanism shown in Fig. 6 or Fig. 7. Fig. 3 shows the slit 44 closed under compression so that any rattle due to manufacturing tolerances is avoided. The slit 44 can be provided advantageously in a liner like those shown in Figs. 8 & 9 having resilient cushion inserts 10 or in liners without inserts 10 as shown in Fig. 7 which are cushioned by stop members 30.

Claims: C A I M S 1. An antifriction element (1) for use between relatively sliding components (2, 3) in a clamping mechanism of an adjustable steering column construction (20) for a vehicle the element being locatable between two said components (2, 3) wherein in an undamped state of the components, a first part of the element acts to urge the components away from contact with one another to allow relative free sliding of the components said part is deflected to allow direct contact between surfaces of the components to provide the clamping friction and wherein the antifriction element allows sliding between limiting stops characterised in that a resilient means (10, 30) is provided between said stops. 2. An antifriction element as claimed in claim 1, wherein the limiting stops are provided by the ends of a slot (4) in the element. . An antifriction element as claimed in claim 2, wherein the resilient means is a separate member (30) inserted in said slot (4) . 4. An antifriction element as claimed in claim 3, wherein the resilient means is formed with a central portion having a hole therethrough, the hole defined by a ribbed surface and so arranged to receive a clamping bar of the mechanism, resilient portions extending outwardly from the central portion, each resilient portion being arranged to buffer against a respective one of the limiting stops of the slot in the element. 5. An antifriction element as claimed in claim 2 wherein the resilient means comprises resilient portions (10) at the ends of the slot (4). 6. An antifriction element as claimed in any one of claims 2 to 5, wherein the slot is defined on each longitudinal side by a wall (40) extending to a surface provided with a slit (44) extending at least most of the length of the slot. 7. A steering column comprising a first clamp member (2), a second clamp member (3) slidable relative to the first clamp member, the first clamp member and second clamp member being in contact with one another when the steering column is in a clamped state; and an antifriction element (1) as claimed in any one of claims 1 to 6 interposed between the first clamp member (2) and the second clamp member (3) .

Inventors: BARTON LAURENCE GEORGE HERBERT, BARTON, LAURENCE, GEORGE, HERBERT
Applicants: TORRINGTON CO, THE TORRINGTON COMPANY LIMITED
Application year: 1995
Main classification: B62D1
IPC codes: B62D1