Steering column for a motor vehicle

Abstract

The present invention relates to a steering column (1) for a motor vehicle, comprising a shell unit (3) in which a steering spindle (4) is rotatably mounted about a longitudinally extending longitudinal axis (L), and which has at least three longitudinally telescopically adjustable shell elements (31, 32, 33) comprising at least an inner shell (33), an outer shell (31) and an intermediate shell (32) arranged between them, on which a two-stage motorized adjustment drive (6) engages, the motorized adjustment drive comprising a first spindle drive arranged between the inner shell (33) and the intermediate shell (32), and a second spindle drive arranged between the intermediate shell (32) and the outer shell (31), wherein the first spindle drive has an outer spindle (62) that engages in a first spindle nut and can be driven in a rotating manner relative to it by a drive unit (61) and extends axially with respect to a spindle axis (S).and the second spindle drive comprises an inner spindle (65) engaging in a second spindle nut and rotatably driven relative to it by the drive unit (61), wherein the first spindle nut is designed as a fixed nut (63) that is fixedly connected to the outer shell (31), and the second spindle nut is designed as a drive nut (66) that is coaxially fixedly connected to the outer spindle (62), which is rotatably mounted and axially supported on the intermediate shell (32), and the inner spindle (65) is connected to the inner shell (33). To enable a more compact design with lower mechanical stress and improved adjustability, the invention proposes that the drive unit (61) be axially fixed to the outer shell (31).

Description

2. Effectively prevents the steering column from penetrating the interior of the passenger compartment and causing injury to the occupants. The outer casing of a steering column of this type has at least three relatively telescopic casing elements, which can also be referred to as telescopic elements or casing tubes. For example, a triple or multiple telescopic arrangement can be formed, with at least three or more telescopically nested casing elements. These comprise an inner casing, also referred to as the inner casing element, which extends coaxially into at least one intermediate casing, also referred to as the middle casing element or intermediate element, which in turn extends telescopically into an outer casing, which is also referred to as the outer casing element or tube. By extending or retracting the casing tubes telescopically, the casing unit, and thus the steering column, can be moved axially, i.e., in the longitudinal direction.shortened or lengthened. 15 A motorized adjustment drive is used to adjust the steering column. This drive has a spindle drive arranged between relatively adjustable outer shell elements. This spindle drive comprises a threaded spindle axially supported on one outer shell element, which engages in a spindle nut axially supported on another outer shell element, which is also adjustable relative to it. The threaded spindle and the spindle nut can be driven by an electric motor 20 to rotate them relative to each other around the threaded or spindle axis, in order to move the outer shell elements axially towards each other or away from each other, depending on the direction of rotation of the drive. For adjusting a multi-telescopic arrangement, it is known from EP4245643A1 25 to provide a two-stage spindle drive comprising two coaxially coupled spindle drives. One of the first, outer spindle drives is a tubular outer spindle run designed as a threaded spindle tube.The drive unit, which is fixed to an intermediate element, can be driven by rotation and engages in a first spindle nut, which is fixed to the outer shell and is referred to as the fixed nut. A second, inner spindle drive is formed by a second spindle nut, the drive nut, which is coaxially fixed to the outer spindle, and an inner spindle engaging therein, which can immerse itself in the hollow outer spindle and is connected to the inner spindle in a way that prevents rotation. When driven by the drive unit, the intermediate shell, together with the drive unit fixed to it, is adjusted relative to the outer shell by the first spindle drive, and at the same time the inner shell is adjusted relative to the intermediate shell by the second spindle drive. BE2024 / 5853 3 The nested, two-stage spindle drive with the inner spindle coaxially mountable within the tubular outer spindle enabled a compact design with a defined adjustment movement between the outer, intermediate, and inner shells. This allowed,Since the drive unit, together with the intermediate sheath, is moved forward or backward relative to the outer sheath (which is fixed in the longitudinal direction relative to the vehicle body) during adjustment, the electrical lines to the drive unit are bent or stretched and must therefore be designed to be flexible and adjustable in length. This requires a relatively large amount of installation space, especially with long adjustment ranges for stowable steering columns, and the connecting cables are subjected to mechanical stress due to the deformation during each adjustment. Furthermore, the drive unit, which moves with each adjustment, represents a relatively large moving mass that must be accelerated by the adjustment drive, so that a relatively high drive power is required for the necessary rapid adjustment. In view of the problems explained above, one task of the present invention is to provide a more compact,To enable a mechanically less stressed structure and improved adjustment. Description of the invention 20 This problem is solved according to the invention by the steering column with the features of claim 1. Advantageous further developments result from the dependent claims. In a steering column for a motor vehicle, comprising a casing unit in which a steering spindle is rotatably mounted around a longitudinally extending longitudinal axis, and which has at least 25 three longitudinally telescopically adjustable casing elements, comprising at least an inner casing, an outer casing and an intermediate casing arranged between them, to which a two-stage motorized adjustment drive engages, which has a first spindle drive arranged between the inner casing and the intermediate casing, and a second spindle drive arranged between the intermediate casing and the outer casing, 30 wherein the first spindle drive engages a first spindle nut and is driven by a drive unit relative to it.with respect to a spindle axis, an outer spindle has an axially extended one, and the second spindle drive has an inner spindle which engages a second spindle nut and is driven by the drive unit relative to it, 35 BE2024 / 5853 4 wherein the first spindle nut is designed as a fixed nut which is fixedly connected to the outer shell, and the second spindle nut is designed as a drive nut which is coaxially fixedly connected to the outer spindle which is rotatably mounted and axially supported on the intermediate shell, and the inner spindle is connected to the inner shell, according to the invention it is provided that 5 the drive unit is axially fixedly attached to the outer shell. The spindle axis denotes the common thread axis of the inner and outer spindles, which extends parallel or essentially parallel to the longitudinal axis. 10 According to the invention, the drive unit, which comprises the electric motor and may have a gearbox arranged between the motor and the spindle drive, is axial,The longitudinal direction relative to the outer shell is fixed in the direction given by the spindle or longitudinal axis. This can, for example, be held by a support unit on the vehicle body and maintains an axial or longitudinal position when the shell unit is adjusted longitudinally, i.e., it is not moved relative to the vehicle body by the motorized adjustment drive. This has the advantage that electrical supply and control lines between the drive unit and a body-mounted electrical control unit of the vehicle are not deformed or moved during adjustment, and are not subjected to bending, compression, or tensile stress. This allows for simpler installation, reduced mechanical stress, and significantly improved use of installation space. A further advantage results from the fact that, during longitudinal adjustment, the drive unit is not moved together with the intermediate shell, as in the previously mentioned state of the art.so that the moving mass can be reduced. This enables faster adjustment of the steering column and a reduction in the required drive power.25 The outer spindle can be driven by the drive unit to rotate relative to the outer shell. In the first spindle drive formed by the rotary spindle drive, it engages with its spindle thread in a fixed nut attached to the outer shell with respect to rotation around the spindle axis, which is rotationally fixed and axially fixed. As the drive rotates, it can be moved axially relative to the outer shell,30 and thus also to the drive unit fixed to it. The outer spindle is axially fixed to the intermediate shell, i.e., rigidly coupled in the direction of the longitudinal axis in both tension and thrust, and is rotatably mounted on the intermediate shell with respect to rotation about the longitudinal axis. This can be achieved, for example, with a thrust bearing. The movement of the rotating outer spindle, which is driven linearly relative to the outer shell, generates a linear axial adjustment of the intermediate shell relative to the outer shell.and specifically, forwards or backwards depending on the direction of rotation. This allows the intermediate shell, coupled to the outer spindle, to be retracted into the outer shell, for example, forwards in the direction of travel of the vehicle 5, or correspondingly extended backwards out of the outer shell. The second spindle drive is formed by the inner spindle engaging the drive nut, which is rotationally and axially fixed to the inner shell. This forms a plunge spindle drive. The drive nut is rotationally fixed to the outer spindle, so that by rotating the outer spindle, the inner spindle engaging the drive nut is moved linearly in the axial direction. It is advantageous that the outer spindle can be axially displaced relative to the drive unit. The outer spindle can be driven by the drive unit to rotate about the spindle axis for adjusting the two-stage spindle drive and can therefore be moved axially, in the direction of the spindle axis, relative to the fixed nut attached to the other drive unit. This makes it possible toThe drive nut, which is rotatably and axially fixed to the outer spindle, is driven to rotate the second spindle nut relative to the inner spindle to actuate the second spindle drive, and at the same time to move the entire second spindle drive, including the drive nut and the inner spindle, which is mounted relative to the outer shell, axially and linearly. This allows the drive of the two-stage spindle drive to be advantageously driven from the outer shell, whereby the drive unit mounted on the outer shell, which is fixed in the longitudinal direction, is not moved during longitudinal adjustment, i.e., it is axially fixed. One advantage is that the electrical control and supply lines of the drive unit, which are connected to a body-mounted control unit, are not moved or deformed during longitudinal adjustment. Another advantage is that the The moving mass is smaller than in the state of the art, where the entire drive unit moves along with the intermediate sleeve when adjusting longitudinally. 30 It may be provided thatthat the fixed nut is connected to the drive unit. The fixed nut can be integrated with the drive unit, so that it can be provided as an assembly-friendly unit that can be fixed to the outer shell as a whole during manufacturing. In addition, a protected arrangement of the fixed nut in a housing of the drive unit is possible. 35 BE2024 / 5853 6 An advantageous implementation can provide that the drive unit has a rotating drive element that interacts with the outer spindle. The drive element is rotatable, axially fixed to the drive unit, and thus axially fixed relative to the outer shell. It is torque-locked to the outer spindle so that it can be driven. The torque-locking connection is designed to prevent axial displacement. 5 To enable the external spindle to rotate relative to the drive pin. When driven by the drive unit, the external spindle performs a rotation around the spindle axis.a linear axial movement is superimposed on the outer spindle and the fixed nut, corresponding to the thread pitch. This movement is directed forward or backward depending on the direction of rotation, whereby the intermediate shell is drawn into or out of the outer shell. Together with the first spindle drive, the coupled second spindle drive is activated. Because the drive nut rotates together with the outer spindle, the inner spindle, which is immersed in it and held fixed relative to the rotation of the inner and intermediate shells, is moved near-axially. Depending on the direction of rotation, the inner shell is adjusted into or out of the intermediate shell, corresponding to the thread pitch of the inner spindle and the drive nut. 20 In the aforementioned embodiment, it may preferably be provided that the driver is formed on a gear wheel of the drive unit that is coaxial with the spindle axis. The gear wheel may, for example, be a gear, a worm gear, a pulley or the like.which can be driven around the spindle axis. It is coupled to the outer spindle via the drive gear and allows axial movement of the outer spindle relative to the gear wheel. The combination of the drive gear with the gear wheel enables a structurally simple, compact and lightweight design. An advantageous further development can be achieved by having the outer spindle pass axially through a through-opening of the driver, which has a radially projecting drive element that engages positively with an axially elongated engagement element of the outer spindle. The driver element can have a drive pin or cam projecting radially inwards into the through-opening, which engages radially from the outside into a corresponding, axially continuous longitudinal groove of the outer spindle that forms the engagement element. This creates a positive locking connection effective with respect to rotation about the spindle axis.A rotary coupling for transmitting the drive torque from the drive unit to the external spindle. The dimensions of the driver and the engagement element are adapted to each other in such a way that the driver pin can slide axially along the longitudinal groove. Accordingly, the external spindle can be driven to rotate and simultaneously displaced in the direction of the spindle axis. This design is structurally simple, compact, robust and functionally reliable. It is possible that the outer spindle and the inner spindle have different thread pitches. The fixed nut and the drive nut have internal threads corresponding to the outer and inner spindles. The respective thread pitch determines the linear axial adjustment travel depending on the relative rotation of the threaded spindle and spindle nut, and accordingly the adjustment speed depending on the rotational speed of the drive. A large thread pitch corresponds to a relatively large linear adjustment travel and a high adjustment speed.and accordingly a smaller thread pitch results in a smaller adjustment range and a lower adjustment speed, but with a higher linear adjustment force. Because the outer spindle is driven by the drive unit to rotate through a predetermined angle at a predetermined speed, different adjustment ranges and adjustment speeds can be achieved for the two spindle drives with a given drive due to the different thread pitches. This allows for an advantageous kind of asymmetric adjustment, which can be individually adapted. For example, sleeve elements with a larger cross-section of the first spindle drive can be extended further relative to each other during adjustment than sleeve elements with a relatively smaller cross-section of the second spindle drive. This allows for the highest possible stiffness of the extended telescopic arrangement. Alternatively, conversely, a relatively faster and greater adjustment of cladding elements with a smaller cross-section is possible.which reduces the masses moved during adjustment. This enables faster adjustment and / or lower required drive power of the drive unit. Alternatively, the thread pitches of the outer and inner spindles are the same. This ensures that the same adjustment speed is achieved when adjusting between the outer and intermediate sleeves and between the intermediate and inner sleeves. It may be provided that a manual steering handle can be attached to the steering spindle. A manual steering handle can, for example, be a steering wheel which can be fixed to a connecting section at the rear end section of the steering spindle. An advantageous further development can provide for the inner casing to have a feedback actuator. To generate a realistic driving feel, it is known to capture parameters such as vehicle speed, steering angle, steering reaction torque, and the like from an actual momentary driving situation or to calculate them in a simulation.and from this a feedback signal is generated, which is fed into a feedback actuator. This actuator drives an electric motor that is coupled to the steering spindle. During driving, the motor is controlled to couple a mechanical return torque (feedback torque) corresponding to the actual reaction torque into the steering wheel via the steering spindle. Such "force feedback" systems give the driver the impression of a real driving situation, as with a conventional steering system, which facilitates an intuitive reaction. The feedback actuator can be fully or partially integrated into the inner casing. It can be advantageous for at least one of the spindle drives to be self-locking.15 This can be achieved by at least one of the threads being self-locking. This can advantageously ensure that even high,No adjustment of the set steering column occurs due to axial forces acting on the adjustment drive. 20 Description of the drawings Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. In detail: 25 Fig. 1 shows a steering column according to the invention in a schematic perspective view, Fig. 2 shows the steering column according to Fig. 1 in a further perspective view, 30 Fig. 3 shows a longitudinal section through the steering column according to Fig. 1 in a retracted adjustment state, Fig. 4 shows a perspective view of the steering column according to Fig. 1 in an extended adjustment state, 35 BE2024 / 5853 9 Fig. 5 shows a longitudinal section analogous to Fig. 3 through the steering column according to Fig. 4 in an extended adjustment state. Embodiment of the invention 5 In the various figures, identical parts are always provided with the same reference numerals and are therefore usually only named or mentioned once. Figs. 1, 2 and 3 show a steering column 1 according to the invention in a predominantly retracted stow position,and Figs. 4 and 5 in an extended operating position. The view in Fig. 10 is from the left rear, obliquely forward, relative to the direction of travel of a vehicle not shown here, and in Fig. 4 is obliquely forward to the right side. The sectional views of Figs. 3 and 5 are oriented from bottom to top. The steering column 1 has an actuating unit 2. This comprises a casing unit 3, which has three casing elements arranged coaxially within one another in the longitudinal direction defined by a longitudinal axis L, namely an outer casing 31, an intermediate casing 32 and an inner casing 33. These are adjustable axially in the longitudinal direction in a telescopic manner, as indicated by the double arrow. 20 In the retracted state, the intermediate shell 32, which is completely immersed forward into the outer shell 31, is concealed in the external views of Figs. 1 and 2 and is only visible in the sectional view of Fig. 3. A steering spindle 4, rotatable about the longitudinal axis L, is mounted in the shell unit 3, which has a connection section 41 at its rear end areas for attaching a manual steering handle (not shown).for example, a steering wheel. The steering spindle 4 can be connected to a feedback actuator 42, which, as schematically indicated in Fig. 3, can be housed in the inner casing 33. 30 The steering spindle 4 can interact with electronic rotation sensors of a steer-by-wire steering system, in which the steering spindle has no direct mechanical connection with the steerable wheels. These rotation sensors are not explicitly shown here and can preferably be housed in the casing unit 3, for example, in the inner casing 33, in order to generate electrical control signals for controlling electric steering actuators interacting with the steerable wheels, depending on a manual steering input. BE2024 / 5853 10 The outer casing unit 3 is held by a support unit 5, which is designed for attachment to a vehicle body (not shown). A motorized adjustment drive 6 according to the invention for telescopic longitudinal adjustment has a drive unit 61,which is fixed to the intermediate shell 32 and supported in the axial direction 5. The drive unit 61 contains an electric motor 610 and is fixed to the outer shell 31 according to the invention. The adjustment drive 6 is designed in two stages and comprises an outer spindle 62 designed as a hollow spindle, which has a spindle axis S parallel to the longitudinal axis L, which can also be referred to as a threaded axis 10. The outer spindle 62 engages with its external thread in a fixed nut 63, which forms a first spindle nut and is visible in the sectional view of Figures 3 and 5. This is rotationally fixed and axially fixed with respect to the spindle axis relative to the outer shell 31. In the example shown, it is fixed in the drive unit 61, which is connected to the outer shell 31. The outer spindle 62 can be driven by a driver 64, which rotates the drive unit 61 around the spindle axis S. The driver 64 is the- designed so that it enables a preferably positive-locking torque transmission to the outer spindle62,and thereby allows a displacement of the outer spindle 62 relative to the drive unit 61. For example, the driver 64 can engage a form-fitting and backlash-free straight in an axially continuous engagement groove on the outside of the outer spindle 62, and slide axially along it. The outer spindle 62 together with the fixed nut 64 forms a first or outer spindle drive. By means of a rotating drive via the drive unit 61, the outer spindle 62 can be displaced axially, linearly in the longitudinal direction relative to the drive unit 61 and thus also relative to the outer shell 31. The outer spindle 62 is rotatable at its front end about the spindle axis S30 via a thrust bearing 34, and is axially fixed in the direction of the spindle axis S with the intermediate shell 32, so that the first spindle drive is inserted between the outer shell 31 and the intermediate shell 32. Accordingly, the intermediate shell 32 can be extended from the retracted adjustment position shown in Fig. 2, which is preferably set for stowing the steering column 1.The rotating drive of the outer spindle 62 is telescopically extended from the outer shell 31-35. This is indicated in Fig. 3 by the left-pointing arrow. BE2024 / 5853 11 A second spindle drive is formed by an inner spindle 65, which is screwed into a drive nut 66, which forms a second spindle nut and is fixed coaxially in the outer spindle 62, preventing rotation and axial fixation. Preferably, the drive nut 66 can be arranged in the area of ​​the thrust bearing 64 in the open through-section of the hollow outer spindle 62. At its front,At the end region axially opposite the intermediate shell 32 and the outer spindle 62, the inner spindle 65 is secured against rotation about the spindle axis S by a transmission element 35 and fixed axially in the direction of the spindle axis S. This means that the second spindle drive, designed as a plunge spindle drive, is arranged between the intermediate shell 32 and the inner shell 33. Accordingly, the inner shell 33 can be extended telescopically from the retracted adjustment position shown in Fig. 210 by the rotating drive of the outer spindle 62 together with the actuation of the first spindle drive, as indicated in Fig. 3 by the left-pointing arrow, until the