STEERING COLUMN FOR A MOTOR VEHICLE

Abstract

A method can be used to adjust a steering column for a motor vehicle that includes a casing unit in which a steering spindle is mounted rotatably about a longitudinal axis and at least two casing tubes that are guided so as to be adjustable relative to one another by adjustment travel in a longitudinal direction of the longitudinal axis. Along the adjustment travel, the casing tubes are extended farther out of one another in an operating region than in a transitional region, and a motorized adjustment drive acting on the casing tubes is actuated electrically for the relative adjustment of the casing tubes at a predetermined adjustment speed. To allow optimized switching between the operating region and the stowage position, a first adjustment speed is set in the operating region and a second adjustment speed, which is higher than the first adjustment speed, is set in the transitional region.

Claims

1.-10. (canceled)

11. A method for adjusting a steering column for a motor vehicle that includes a casing unit in which a steering spindle is mounted rotatably about a longitudinal axis and at least two casing tubes that are guided so as to be adjustable relative to one another by an adjustment travel in a longitudinal direction of the longitudinal axis, wherein along the adjustment travel the at least two casing tubes are extended farther out of one another in an operating region than in a transitional region, the method comprising: electrically actuating a motorized adjustment drive acting on the at least two casing tubes for relative adjustment of the casing tubes at a predetermined adjustment speed, wherein a first adjustment speed is set in the operating region and a second adjustment speed is set in the transitional region, with the second adjustment speed being higher than the first adjustment speed.

12. The method of claim 11 wherein the at least two casing tubes are retracted farther into one another in a stowage region than in the transitional region, wherein a third adjustment speed is set in the stowage region, with the third adjustment speed being lower than the second adjustment speed.

13. The method of claim 12 wherein the at least two casing tubes are movable relative to one another at least partially with a smaller adjustment force in the transitional region than in the stowage region.

14. The method of claim 11 wherein the predetermined adjustment speed changes linearly.

15. The method of claim 11 wherein the predetermined adjustment speed changes non-linearly.

16. The method of claim 11 comprising detecting a relative position of the at least two casing tubes with a position sensor.

17. The method of claim 11 wherein the adjustment drive exerts a higher adjustment force at a lower adjustment speed than at a higher adjustment speed.

18. The method of claim 11 wherein the at least two casing tubes are movable relative to one another at least partially with a smaller adjustment force in the transitional region than in the operating region.

19. The method of claim 11 wherein the steering column includes a motorized height adjustment drive disposed between the casing unit and a carrier unit that is positionable on a body of the motor vehicle, wherein the motorized adjustment drive is electrically actuatable for relative height adjustment of the casing unit transversely to the longitudinal axis with a predefined height adjustment speed.

20. The method of claim 19 wherein the relative height adjustment occurs at least partially simultaneously with the adjustment travel in the direction of the longitudinal axis.

21. The method of claim 19 wherein the relative height adjustment occurs in the transitional region.

Description

DESCRIPTION OF THE DRAWINGS

[0057] Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. These show:

[0058] FIG. 1 a steering column according to the invention in a schematic perspective view,

[0059] FIG. 2 the steering column from FIG. 1 in a schematic, partially opened internal view,

[0060] FIG. 3 the steering column from FIG. 1 in a further schematic, partially opened internal view,

[0061] FIG. 4 a longitudinal section through the steering column from FIG. 1,

[0062] FIG. 5 an enlarged detail view of FIG. 4,

[0063] FIG. 6 a cross-section A-A through the steering column from FIG. 4,

[0064] FIG. 7 a longitudinal section through a second embodiment of a steering column according to the invention,

[0065] FIG. 8 an enlarged detail view of FIG. 7,

[0066] FIG. 9 a schematic detail view of FIG. 7, showing the steering column in a first comfort region in the operating region,

[0067] FIG. 10 a schematic detail view of FIG. 7, showing the steering column in a transitional region,

[0068] FIG. 11 a schematic detail view of FIG. 7, showing the steering column in a first comfort region/stowage region in the stowage position,

[0069] FIG. 12 a schematic sectional view of the steering column from FIG. 7,

[0070] FIG. 13 adjustment force-travel, speed-travel and friction force-travel diagrams of a steering column according to the invention,

[0071] FIG. 14 adjustment force-travel and friction force-travel diagrams similar to FIG. 13, and a modified speed-travel diagram,

[0072] FIG. 15 associated speed-travel diagrams in the longitudinal and height direction,

[0073] FIG. 16 a second embodiment of a steering column for performance of the method according to the invention, in a schematic perspective view,

[0074] FIG. 17 a speed-travel diagram during adjustment of the steering column from FIG. 16,

[0075] FIG. 18 a modified speed-travel diagram during adjustment of a steering column, similar to FIG. 16.

EMBODIMENTS OF THE INVENTION

[0076] In the various figures, the same parts always carry the same reference signs and therefore usually only cited or mentioned once.

[0077] FIG. 1 shows, in an oblique view from the rear with respect to the direction of travel, a steering column 1 having an actuator unit 2. The actuator unit 2 comprises a casing unit 3 which has an outer casing tube 31, an intermediate casing tube 32 and an inner casing tube 33. The casing tubes 31, 32 and 33 are arranged so as to be telescopically displaceable coaxially in one another in the longitudinal direction, which corresponds to the axial direction of the longitudinal axis L, as indicated with a double arrow.

[0078] A steering spindle 4 is mounted in the casing unit 3 so as to be rotatable about the longitudinal axis L, and at its rear end has a connecting portion 41 for attachment of a steering wheel (not shown).

[0079] The casing unit 3 is held in a two-part carrier unit 5, which has fixing means 51 for attachment to a vehicle body (not shown).

[0080] An adjustment drive 6 for length adjustment, also called a length adjustment drive, has a spindle drive with a spindle nut 61 and a threaded spindle 62 screwed therein which can be driven in rotation with respect to one another by an electric motor 63. The threaded spindle 62 extends parallel to the longitudinal axis L and is connected to the inner casing tube 33, and the spindle nut 61 is supported via the adjustment drive 6 on the outer casing tube 31 in the length direction, which corresponds to the axial direction of the longitudinal axis L, wherein the outer casing tube 31 has a fork portion, and wherein the adjustment drive 6 is coupled to the fork portion via the interposition of a damping rubber element 666 formed as a silent bush. A relative rotation by means of the motor 63 causes the threaded spindle 62 and spindle nut 61 to move towards each other or away from one another, depending on the direction of rotation, whereby the inner casing tube 33 is retracted into or extended out of the outer casing tube 31 in the axial direction, as indicated by the double arrow. This causes a length adjustment, by means of which a steering wheel arranged at the connection portion 41 can be moved forward—to the left in the depiction of FIG. 1—into a stowage position, in which the inner casing tube 33 and intermediate casing tube 32 are retracted into the outer casing tube 31, i.e. compressed towards the front, or into an operating position in the operating region in which the casing tubes 31, 32 and 33 are extended out of one another.

[0081] Alternatively, the spindle nut 61 may rest on the inner casing tube 33, and the threaded spindle 62 on the outer casing tube 31.

[0082] FIG. 2 shows, in a perspective view from the front, the cut-away outer casing tube 31 which has been partially omitted to give a view of the intermediate casing tube 32. FIG. 3, in a view similar to FIG. 1, shows the cut-away intermediate casing tube 32.

[0083] FIG. 4 shows a longitudinal section along the longitudinal axis L, and FIG. 5 a detailed view thereof. FIG. 6 shows a cross-section A-A according to FIG. 4.

[0084] The casing tubes 31, 32 and 33 have an octagonal profile cross-section, as evident from FIG. 6 which shows a cross-section A-A from FIG. 4 through the casing unit 3 in partially extended state, in which the inner casing tube 33 and the intermediate casing tube 32 are partially retracted into the outer casing tube 31. It is clear that the first rollers 7 are arranged between the outer casing tube 31 and the intermediate casing tube 32, and the second rollers 8 between the intermediate casing tube 32 and the inner casing tube 33. The rollers 7 or 8 are here each mounted in the casing tubes 32 and 33 so as to be rotatable about their respective roller axes 71 and 81 lying transversely to the longitudinal axis L. The rollers 7 protrude radially outward from the outer cross-section of the intermediate casing tube 32, so that they can roll on the inside of the outer casing tube 31 in the axial direction, and similarly the rollers 8 protrude from the outer cross-section of the inner casing tube 33 so they can roll on the inside of the intermediate casing tube 32 in the axial direction. The rollers 7 and 8 are arranged in rows each of five rollers 7, 8 in the axial direction on every second side of the octagonal profile of the casing tubes 32, 33, with an angular offset α of 360°/8=45°, offset on gaps in the circumferential direction, between the intermediate casing tube 32 and the inner casing tube 33, as evident from the cross-section shown in FIG. 6.

[0085] In the region of its front body-side end, the outer casing tube 31 has a first inner bearing portion 311 with an internal width dl and, adjoining this in the axial direction towards the rear, a guide portion 312 with a greater internal width d2, i.e. d1<d2; the latter is followed in the axial direction towards the rear by a second inner bearing portion 313 with an internal width dl of the first bearing portion 311. The respective internal width is the inner distance between two parallel opposing flat portions of the octagonal profile cross-section, wherein the rollers 7 roll on these flat portions. If casing tubes 31, 32, 33 with circular cylindrical cross-sections are used, the inner width of the respective portion is identical to the inner diameter of the respective portion.

[0086] The axial region of the total of five rollers 7 forms an outer bearing portion 321 on the intermediate casing tube 32, which has an outer width dl measured on the outside over the protruding rollers 7 and is thus identical to the inner width dl of the inner bearing portions 311 and 313. In this way, the rollers 7 can roll without play in the bearing portions 311 and 313. In the axial direction towards the rear, the outer bearing portion 321 is followed by an outer guide portion 322 with a smaller outer width d3, wherein d3<d1.

[0087] In the front end region, the intermediate casing tube 32 has an inner guide portion 323 with an inner width d4, which is followed in the axial direction towards the rear by an inner bearing portion 324 with a smaller inner width d5, i.e. d4>d5.

[0088] In a similar fashion to the intermediate casing tube 32, the inner casing tube 33 has an outer bearing portion 331 which is formed by the row of a total of five rollers 8, and has an outer width d5 measured over the outwardly protruding rollers 8 which thus corresponds to the inner width d5 of the inner bearing portion 324 of the intermediate casing tube 32, so that the rollers 8 can roll without play. In the axial direction towards the rear, the outer bearing portion 331 is followed by an outer guide portion 332 with a smaller outer width d6, wherein d6<d5.

[0089] The rollers 7 of the outer bearing portion 321 may roll without play, with zero play (=0), in the axial direction on the inside in the inner bearing portions 311 and 313 during a relative adjustment of the casing tubes 31 and 32. Thus the telescopic connection is supported play-free with high stiffness, and in the sense of the invention an adjustment takes place in the comfort region. If the casing tubes 31 and 32 are moved relative to one another in the longitudinal direction for retraction or extension, the rollers 7 in the guide region 312 have a radial play S of the size of the difference (d2−d1) from the inside of the outer casing tube 31. This is shown enlarged in the detail depiction of FIG. 5.

[0090] The inner casing tube 33 is mounted in the intermediate casing tube 32 in a similar fashion. The rollers 8 of the outer bearing portion 331 can roll play-free, with play=0, in the axial direction on the inside in the inner bearing portion 324 during relative adjustment of the casing tubes 32 and 33. Thus the telescopic connection is supported play-free with high stiffness, and in the sense of the invention an adjustment takes place in the comfort region. If the casing tubes 32 and 33 are moved relative to one another in the longitudinal direction for retraction or extension, the rollers 8 in the guide region 323 have a radial play S of the size of the difference (d4−d5) from the inside of the intermediate casing tube 32. This is shown enlarged in the detail depiction of FIG. 5 with the reference signs in brackets.

[0091] The total adjustment travel of the steering column 1 corresponds to the sum of the adjustment travels in the comfort regions and in the transitional region. Because of the greater play S, for adjustment in the axial direction, a smaller friction force must be overcome in the transitional region than in the comfort regions in the operating region and in the region of the stowage position, or the stowage region. The adjustment drive 6 must have a higher adjustment force, the operating adjustment force, for adjustment in the operating region than in the transitional region, where only a small stowage adjustment force need be applied. At the rear end of the outer casing tube 31, a stop 34 is arranged which protrudes inwardly at the open end into the intermediate space between the outer casing tube 31 and the intermediate casing tube 32. On extension, the rollers 7 of the intermediate casing tube 32 in the outer bearing portion hit against the stop 34 in the axial direction, providing security against separation from the outer casing tube 31. At the rear end of the intermediate casing tube 32, a stop 35 is arranged which protrudes inwardly into the intermediate space between the intermediate casing tube 32 and the inner casing tube 33, and secures the inner casing tube 33 against coming out of the intermediate casing tube 32 in that the rollers 7 meet the stop in the axial direction.

[0092] The steering spindle 4 is also designed telescopic with an inner shaft 43 which is telescopic in the longitudinal direction and engages by form fit in an outer shaft 42, wherein a guide sleeve 44 is arranged in-between to ensure an easy slide guidance. Alternatively, a linear roller bearing guide may be provided between the inner shaft 43 and the outer shaft 42.

[0093] FIGS. 7 to 12 show a further embodiment of the invention which has tubular sliding sleeves 92 and 93 instead of the rollers 7, 8. The sliding sleeve 92 is attached to the rear of the intermediate casing tube 32 so as to form an outer bearing portion 321, wherein it has an outer width of substantially dl and its length in the axial direction corresponds approximately to the length of the row formed by the five rollers 7 on the intermediate casing tube 32 in the first embodiment. Correspondingly, a further sliding sleeve 93 is attached to the rear of the inner casing tube 33 in order to form an outer bearing portion 331, wherein it has an outer diameter of approximately d5 and its length in the axial direction corresponds to the row formed by the five rollers 7 on the intermediate casing tube 32 in the first embodiment.

[0094] In the enlarged detail depiction of FIG. 8 which corresponds in content to FIG. 5 of the first embodiment, the arrangement of the sliding sleeves 92 can be seen, wherein the arrangement is similar between the casing tubes 32 and 33.

[0095] FIG. 9 shows schematically a steering column with circular cylindrical casing tubes 31, 32 in a comfort region in the extended state which corresponds to the operating region. The sliding sleeve 92, as an outer bearing portion 321 with the outer diameter dl formed as an outer width, is mounted with low play or zero play in the inner bearing portion 311 of the outer casing tube 31. The adjustment drive 6 allows a relative adjustment in the axial direction for fine setting of the steering wheel position, wherein the comfort adjustment force K is to be applied.

[0096] FIG. 10 shows a steering column in a transitional region in which the casing tube 32 is retracted forward, to the left in the drawing, out of the operating region. The sliding sleeve 92 and hence the outer bearing portion 321 has a distance in the axial direction from the inner bearing portion 313, and is situated in the inner guide portion 312 where it has a play S=(d2−d1) from the inner wall of the outer casing tube 31. Because the friction force is reduced by the play S, for retraction only a transitional adjustment force F is required which is smaller than the operating adjustment force K (equal to the comfort adjustment force) as indicated by the force arrow. F<K.

[0097] As soon as, on further retraction out of the guide portion 312, the sliding sleeve 93 enters the inner bearing portion 311 out of the guide portion 312 as shown in FIG. 11, the comfort region (stowage region) of the stowage position is reached. Here again, a play-free mounting takes place, as in the bearing portion 313. Because the bearing portions 311 and 313 in the example have the same inner diameter d1, for adjustment here again the comfort adjustment force K is required. It is also conceivable and possible that the inner bearing portion 311 has a smaller or larger inner diameter in order to predefine the comfort adjustment force K as larger or smaller.

[0098] FIG. 12 shows schematically a multiple telescopic arrangement with the casing tubes 31, 32 and 33, and the sliding sleeves 92 and 93 which cooperate in the similar fashion to that shown in FIGS. 9 to 11.

[0099] The total adjustment travel of the steering column 1 comprises the adjustment positions in the comfort regions according to FIGS. 9 and 11, and in the transitional region according to FIG. 10, which can be set or traversed respectively on complete retraction and extension. Because of the greater play S, for adjustment in the transitional region, a smaller friction force must be overcome than in the comfort regions in the operating region and in the region of the stowage position.

[0100] FIG. 13 shows a diagram which shows in a) the adjustment force F, in b) the adjustment speed v, and in c) the friction force, in each case over the adjustment travel x (parallel to the longitudinal axis L). Here x1 corresponds to the adjustment in the operating region in the adjustment state shown in FIG. 11, x2 corresponds to the adjustment in the transitional region in the adjustment state shown in FIGS. 10, and x3 corresponds to the adjustment in the comfort region/stowage region of the stowage position Xv in the adjustment state shown in FIG. 9.

[0101] It is clearly evident from FIG. 13.a) how the adjustment force necessary for the relative movement of the casing tubes 31, 32 and 33 diminishes, on adjustment between the comfort regions, from the comfort adjustment force K to the lower transitional adjustment force F. As a consequence, an adjustment drive 6 with a specific drive power can achieve a higher adjustment speed in the transitional region, as shown in FIG. 13.b). The friction force c to be overcome for adjustment, as shown in FIG. 13.c), behaves similarly to the adjustment force. The radial and vertical stiffness of the steering column behaves similarly to the friction force shown in FIG. 13.c).

[0102] According to the method of the invention, the adjustment drive 6 is actuated so as to execute an adjustment, in the operating region x1, with a first adjustment speed v1 known as the adjustment or positioning speed, wherein a high operating adjustment force K is exerted. In the transitional region x2 adjoining the operating region x1, a faster adjustment takes place with the second adjustment speed v2 or the transitional speed, wherein a lower stowage adjustment force F is exerted.

[0103] FIG. 14 corresponds to the diagrams of FIG. 14 in the depictions of 14.a) and 14.c). The adjustment in operating region x1 takes place with a third adjustment speed v3, wherein v3=v2 may be the case, or as shown v2>v3>v1.

[0104] A difference is that, at both the start and end of the regions x1, x2 and x3, and hence also at the transition between the regions x1, x2 and x3, the adjustment speed is increased between zero and v1, between v1 and v2, between v2 and v3, and reduced between v3 and zero in the acceleration portions A, with constant acceleration. As an alternative to the linear rise and fall in adjustment speed v as shown, progressive and/or degressive change rates may be implemented.

[0105] The casing unit 3 may be adjusted in the height direction H by means of a second adjustment drive 60 which forms a height adjustment drive and is shown in FIG. 2, wherein this may be formed as a spindle drive similarly to the adjustment drive 6 and acts on the actuating unit 2 and the carrier unit 5.

[0106] By means of the adjustment drive 60, a height adjustment may take place in the y direction parallel to the height direction H. In the diagram shown in FIG. 15.b), y3 designates a height position in the stowage position, y2 in the transitional region, and y1 in the operating region. In FIG. 15.a), the x adjustment is given as in FIG. 14.b), and in FIG. 15.b) the corresponding speed-travel diagram of a height adjustment in the y direction (parallel to the height direction H), in which the height adjustment speed is shown over the height position y. It is evident that a height adjustment takes place with a height adjustment speed vH only in the transitional region x2. Thus a combined, fast stowage adjustment takes place simultaneously in the length and height direction only in the transitional region x2 outside the operating region x1.

[0107] Evidently, a height adjustment may take place in the operating region also by means of a control command entered by the vehicle driver. The diagrams shown in FIG. 15 show the adjustment speeds of the inner casing tube relative to the outer casing tube or carrier unit during the switch between autonomous and manual driving modes.

[0108] FIG. 16 shows, in a view similar to FIG. 1, a second embodiment of a steering column 1 intended for performance of the method according to the invention, wherein the same reference signs are used for parts of equivalent function.

[0109] In contrast to the embodiment of FIG. 1, the telescopic arrangement of the casing unit 3 is formed only by the inner casing tube 33 guided telescopically in the outer casing tube 31. There is no intermediate casing tube 32, but otherwise the function is similar.

[0110] FIGS. 17 and 18 show speed-travel diagrams which correspond to the diagrams in FIGS. 13.b) and 14.b). In the transitional region x2, the adjustment takes place with the transitional speed v2 which is higher than the adjustment speed v1 in the operating region x1. The stowage position Xv is arranged at the end of the transitional region x2. In this embodiment, there is no stowage region, or it could be said in other words that the stowage region is formed by the stowage position. As FIG. 18 shows, acceleration portions A may be provided between the different adjustment speeds of zero, v1 and v2, in which the adjustment speed is increased or reduced with constant acceleration. As an alternative to the linear rise and fall of the adjustment speed v shown, also progressive and/or degressive change rates may be implemented.

LIST OF REFERENCE SIGNS

[0111] 1 Steering column [0112] 2 Actuator unit [0113] 3 Casing unit [0114] 31 Outer casing tube [0115] 311 Inner bearing portion of 31 [0116] 313 Inner bearing portion of 31 [0117] 312 Inner guide portion of 31 [0118] 32 Intermediate casing tube [0119] 321 Outer bearing portion of 32 [0120] 322 Outer guide portion of 32 [0121] 323 Inner guide portion of 32 [0122] 324 Inner bearing portion of 32 [0123] 33 Inner casing tube [0124] 331 Outer bearing portion of 33 [0125] 332 Outer guide portion of 33 [0126] 34, 35 Stop [0127] 4 Steering spindle [0128] 41 Connecting portion [0129] 42 Outer shaft [0130] 43 Inner shaft [0131] 44 Guide sleeve [0132] 5 Carrier unit [0133] 51 Fixing means [0134] 6 Adjustment drive (length adjustment drive) [0135] 60 Height adjustment drive [0136] 61 Spindle nut [0137] 62 Threaded spindle [0138] 63 Motor [0139] 7, 8 Rollers [0140] 71, 81 Roller axes [0141] 92, 93 Sliding sleeves [0142] d1 Inner diameter of 311/outer diameter of 321 [0143] d2 Inner diameter of 312 [0144] d3 Outer diameter of 322 [0145] d4 Inner diameter of 323 [0146] d5 Inner diameter of 324/outer diameter of 331 [0147] d6 Outer diameter of 332 [0148] L Longitudinal axis [0149] S Play [0150] K Operating adjustment force (comfort adjustment force) [0151] F Stowage adjustment force (transitional adjustment force) [0152] C Friction force [0153] x1 Operating region [0154] x2 Transitional region [0155] x3 Stowage region [0156] v1 First adjustment speed [0157] v2 Second adjustment speed [0158] v3 Third adjustment speed [0159] vH Height adjustment speed