DE102021212818A1 - Adjustment drive for a steering column of a motor vehicle and steering column for a motor vehicle - Google Patents

Abstract

The present invention relates to an adjustment drive (1) for a steering column of a motor vehicle, with a spindle drive comprising a threaded spindle (7) with an external thread (71, 72) which engages in an internal thread (81) of a spindle nut (8), the external thread (71, 72) has a continuously circumferential threaded tooth (73) and a threaded groove (74), and the threaded spindle (7) can be driven in rotation relative to the spindle nut (9). In order to enable optimized engine operation and an improvement in the acoustic properties, the invention proposes that the external thread (71, 72) have a first thread section (71) with a first thread pitch (P1) and a second thread section (72) with one of the first thread pitch (P1) has different second thread pitch (P2).

Description

State of the art

The invention relates to an adjusting drive for a steering column of a motor vehicle, with a spindle drive comprising a threaded spindle with an external thread, which engages in an internal thread of a spindle nut, the external thread having a continuously circumferential threaded tooth and a threaded groove, and the threaded spindle being drivable in rotation relative to the spindle nut is. A steering column with such an adjustment drive is also the subject of the invention.

A steering column for a motor vehicle has a manual steering input means at its rear end in the direction of travel, facing the driver, for introducing a steering command. such as a steering wheel. This is mounted in an actuating unit and attached, for example, to a steering spindle, which is pivoted about its longitudinal axis in the actuating unit and is connected to a steering shaft. The actuating unit is held by a support unit on the vehicle body.

Due to the fact that the control unit, for example in a jacket unit connected to the support unit, is accommodated so as to be displaceable in the direction of the longitudinal axis, for example in a telescopic jacket tube arrangement, a longitudinal adjustment of the steering input means can take place relative to the driver's position. A height adjustment can be realized in that the setting unit or a jacket unit receiving it is mounted on the support unit such that it can pivot upwards or downwards. The adjustment of the control unit in the lengthwise or heightwise direction enables an ergonomically comfortable steering wheel position to be set relative to the driver's position in the operating position, also known as the driving or operating position, in which manual steering intervention can take place.

In order to adjust the adjustment unit relative to the support unit, it is known in the prior art to provide an adjustment drive of the type mentioned at the outset with a motorized drive unit. This has an electric motor, which is connected to a spindle drive, which includes a threaded spindle screwed into a spindle nut, usually via a gear. By means of the drive unit, the threaded spindle and the spindle nut can be driven in rotation about the spindle axis in opposite directions, as a result of which they can be moved towards one another or away from one another in a translatory manner, depending on the direction of rotation in the direction of the spindle axis. In one embodiment, a so-called rotary spindle drive, the threaded spindle can be driven by the drive unit, which is fixedly connected to the actuating unit or the support unit and supported axially, to rotate about its threaded spindle axis and engages in the spindle nut, which is attached to the support unit or the actuating unit with regard to rotation fixedly mounted and axially supported around the spindle axis. A rotary drive of the threaded spindle correspondingly brings about a translational adjustment of the support unit and the actuating unit relative to one another.

In an alternative embodiment, referred to as a plunger spindle drive, the threaded spindle is non-rotatably coupled to the support unit or the setting unit with respect to rotation about its spindle axis and the spindle nut is rotatable but fixed in the direction of the spindle axis on the setting unit or the support unit. As in the first embodiment, the threaded spindle is supported axially in the direction of the spindle axis on the support unit or the setting unit, and the spindle nut correspondingly on the setting unit or the support unit, so that the threaded spindle can be displaced translationally by the drive unit in the direction of the spindle axis. In both versions, the spindle drive forms an adjustment drive that is effective between the support unit and the control unit and by which the control unit can be adjusted relative to the support unit for the purpose of adjustment.

A generic adjustment is for example in DE 10 2014 103 879 A1 described. The threaded spindle has an external thread which—as is known from spindle drives—is screwed into the internal thread of the spindle nut. The external thread has a helically circumferential thread tooth that runs continuously over its entire axial thread length corresponding to the possible adjustment path, and correspondingly a thread groove that runs adjacent thereto. To produce the thread engagement, an internal thread tooth of the spindle nut engages in the thread groove in a manner known per se.

On the one hand, the adjustment drive enables an optimal operating position to be set for a comfortable manual steering intervention within an operating area that forms a subarea of the entire possible adjustment area or adjustment path and is also referred to as the operating or comfort area. On the other hand, the adjusting drive enables the steering column to be stowed away, for example during autonomous driving of an autonomously driving vehicle and/or for entering and exiting the vehicle, in which case the steering input means is brought into a stowed position outside the operating area. To set the stowage position, the steering column is retracted or retracted as far as possible by means of one or more adjusting drives drive so that the vehicle interior can be released for other uses. To adjust the operating or operating position, the steering column is extended in the reverse direction from the stowed position.

A relatively low adjustment speed is advantageous for sensitive and precise adjustment of the operating position, whereas stowage should take place at the highest possible adjustment speed.

The adjusting speed of the known adjusting drive results from the rotational speed of the drive of the threaded spindle relative to the spindle nut, multiplied by the thread pitch, or pitch for short, of the spindle thread. Correspondingly, the drive unit is operated at a low engine speed for slow adjustment of the operating position, which is converted into the rotational speed via a predetermined translation, and at the highest possible engine speed for fast stowage.

In principle, an electric motor enables the speeds required for slow and fast adjustment without an additional manual transmission. However, one disadvantage can result from the fact that the motor has to be operated at least partially outside of its optimal operating range due to the large difference in the speeds. In addition, it is unavoidable that drive noises occur in different frequency ranges at the different speeds of the engine. These acoustic emissions can be perceived as annoying, especially when quickly changing between the stowage and operating position or vice versa.

In view of the problems explained above, it is an object of the present invention to enable optimized motor operation and an improvement in the acoustic properties in an adjustment drive.

Presentation of the invention

According to the invention, this object is achieved by the adjusting drive according to claim 1 and the steering column according to claim 15. Advantageous developments result from the dependent claims.

In an adjustment drive for a steering column of a motor vehicle, with a spindle drive comprising a threaded spindle with an external thread which engages in an internal thread of a spindle nut, the external thread having a continuously circumferential threaded tooth and a threaded groove, and the threaded spindle being drivable in rotation relative to the spindle nut, the invention provides that the external thread has a first thread section with a first thread pitch and a second thread section with a second thread pitch that differs from the first thread pitch.

Insofar as the two thread sections or the two thread pitches are mentioned below, this means a joint reference to the first and the second thread section, or to the first and the second thread pitch.

The thread groove running together with the thread tooth can also be referred to as thread groove, thread valley or thread groove. The thread tooth has a first and second tooth flank, the thread groove being formed by the spiral course. The pitch of the thread tooth is the path covered by the thread tooth in one revolution (360°). The tooth flanks form the thread flanks of the thread groove. The thread groove is formed by the first tooth flank and the second tooth flank of the thread tooth after one revolution.

The thread lead, or pitch for short, is by definition the axial distance between two points with the same angular orientation on adjacent turns of the thread tooth. In the case of a single-start thread, the thread pitch corresponds to the sum of the tooth width, this is the axial width of the thread tooth, and the groove width, this is the axial width of the thread groove. In the case of a multiple thread, this sum is multiplied accordingly by the number of threads.

According to the invention, the external thread is formed from the first and the second threaded section, ie the two threaded sections, by at least one common, continuous thread tooth. In other words, the thread tooth extends continuously over both thread sections. The thread groove is also formed continuously throughout.

The two threaded sections adjoin one another axially, with the thread tooth and the thread groove extending over the length of the external thread formed from the two threaded sections. According to the invention, the spindle nut is designed in such a way that thread engagement with both thread sections is possible.

The fact that the two threaded sections according to the invention have different pitches, the adjustment speed, the resulting from the product of the pitch and the relative rotational speed of the threaded spindle and the spindle nut, can be specified differently in sections while the speed of the drive unit remains the same. A threaded section with a relatively small pitch, which forms a first threaded section, for example, allows relatively slow adjustment at a given engine speed, preferably for sensitive and comfortable setting of an optimal operating position in the manual, extended operating range of the steering column. According to the invention, this first threaded section, which covers the adjustment range of possible operating or operating positions, is followed by the second threaded section with a different pitch, for example with a second pitch that is greater than the first. When the thread engagement of the spindle nut transitions from the first to the second thread section when adjusting, the second thread pitch becomes effective and vice versa. Due to the greater second gradient, an adjustment can be implemented with a greater adjustment speed while the engine speed remains the same. This makes it possible to run through an adjustment area that follows the operating area at a higher speed until a retracted stowage position is reached, with the motor speed of the drive unit remaining the same.

The ratio of the adjustment speeds can be predetermined at a given, preferably constant speed of the drive with little effort by the pitch ratio of the two threaded sections.

An advantage of the invention is that the speed of the drive unit can be kept constant or at least essentially constant during operation, which means that the operating noise can be made more uniform, even if different adjustment speeds are implemented. For acoustic optimization, it is possible to specify the speed of the drive device and the motor and to adjust it to the pitch of the threaded spindle in such a way that the frequencies occurring during adjustment are within acceptable ranges that are perceived as acoustically pleasant.

It is also advantageous that the transmission ratio between the rotational speed and the adjustment speed can be adjusted, if necessary also by means of an intermediate gear ratio, so that the electric motor can be operated in the optimum range. As a result, the efficiency of the drive can be increased, making it possible to optimize energy consumption, installation space and weight.

It is a further advantage that due to the continuous design of the thread tooth and the thread groove, an independent, positively controlled changeover of the transmission ratio between the speed of the drive and the linear adjustment speed of the spindle drive, which is predetermined by the pitch, can be implemented. The transition from the first to the second adjustment speed takes place simply by the uninterrupted thread engagement of the spindle nut with the thread tooth that runs continuously over the entire external thread, over both thread sections.

The transition of the spindle nut between the two threaded sections can take place without additional moving parts, solely via the continuous thread engagement with the common thread tooth or the thread groove.

It can be provided that the second thread pitch is greater than the first thread pitch. This corresponds to a gradient ratio of the second to the first gradient greater than 1:1. A smaller gradient means that, for a given speed of the drive, a slower axial adjustment takes place, and is therefore preferably arranged in the area of the threaded spindle that corresponds to the operating or operating area in an extended adjustment state.

It is advantageous that the pitch ratio between the second thread pitch and the first thread pitch is greater than 1.5:1. As a result, a significantly faster adjustment can be implemented in an advantageous manner with the same speed of the drive, for example for stowage.

It is also advantageous that the pitch ratio between the second thread pitch and the first thread pitch is less than 20:1. As a result, when changing the adjustment speed, the forces and accelerations acting at the transition between the two threaded sections can remain within acceptable magnitudes.

A particularly preferred embodiment can provide that the pitch ratio between the second thread pitch and the first thread pitch is 10:1. This can advantageously be optimized taking into account a slow adjustment that is perceived as haptically pleasant to adapt the operating position, and at the same time a faster adjustment that is perceived as sufficiently rapid and still safe can be implemented into the stowed position or in the operating position.

An advantageous embodiment of the invention can be realized in that the internal thread has at least one internal thread tooth which can be brought into threaded engagement with the external thread in the first threaded section and the second threaded section. The internally threaded tooth can preferably be designed as an internally threaded segment or toothed segment, which projects radially inwards in the threaded bore of the spindle nut and preferably extends over a partial circumferential section that does not include a closed thread turn. The internally threaded tooth is preferably designed in terms of shape and dimensions such that it can be brought into threaded engagement with either threaded section. For example, the internal thread tooth can engage in the thread groove in a form-fitting manner in such a way that it slidingly contacts the opposite thread flanks of a thread groove in the area of contact surfaces.

An advantageous realization of the above-mentioned embodiment can be achieved in that the internal thread tooth has two pairs of flanks, a first pair of flanks being able to be brought into threaded engagement with the thread groove in the first thread section, and a second pair of flanks being able to be brought into threaded engagement with the thread groove in the second thread section. The internally threaded tooth, which preferably has at least one toothed segment, protrudes radially inwards in the spindle nut, directed towards the longitudinal axis. Two first tooth flanks are arranged as a first pair of flanks and are inclined at a first pitch angle corresponding to the first pitch against the circumferential direction (which is perpendicular to the longitudinal axis) such that they are in sliding contact with defined first contact surfaces on opposite tooth flanks of the first thread section. Two second tooth flanks of the internal thread tooth, which differ from the first tooth flanks, form a second pair of tooth flanks, which is inclined at a second pitch angle corresponding to the second pitch against the circumferential direction. Correspondingly, the two pairs of flanks are angularly offset relative to one another with respect to an imaginary radial axis projecting radially outwards from the longitudinal axis by the difference between the two pitch angles. The respective distances between the tooth flanks of the two pairs of flanks define two different inner tooth widths, with the first inner tooth width corresponding to the first groove width of the thread groove in the first thread section, and the second inner tooth width corresponding to the second groove width of the same thread groove in the second thread section. As a result, a defined thread engagement can be realized in both thread sections, even if the thread groove has a different groove width in the two thread sections. It is advantageous that the internal thread tooth with the two pairs of flanks can be implemented with little effort and offers a high level of functional safety. Due to the mutually independent design of the tooth width of the two pairs of flanks, which corresponds to the distance between the opposite tooth flanks, the contact surface and also the thread play can be specified in a defined manner for each of the two thread sections. This allows, for example, an easier, faster adjustment with greater thread play and a smaller contact area in the area of the larger pitch, for example for stowing away, and a slower, more precise adjustment with greater rigidity and a larger contact area in the area of the smaller pitch, for example for sensitive adjustment of the operating position.

In the embodiment mentioned above, it is advantageous that a contact surface between the internal thread and the external thread in the first threaded section is different from the second threaded section. The contact surface is defined by the surface in which there is sliding contact between the tooth flanks of the internal tooth and the external thread in the threaded engagement. A larger contact section in the threaded section with a smaller pitch allows greater rigidity there, which is advantageous for the required high level of rigidity of the steering column in the operating position. On the other hand, in the threaded section with a larger pitch, which is only passed through quickly when moving into or out of the stowed position, a smaller contact section is sufficient because of the lower requirements for rigidity, which enables lower thread friction. Contact sections with different dimensions can be conveniently implemented on an internally threaded tooth with two pairs of flanks, one of the pairs of flanks having a smaller or larger contact surface, preferably in the area of the smaller pitch.

In one embodiment of the invention, it can be provided that the spindle nut has at least two internally threaded teeth which are offset in the circumferential direction and between which thread gaps are formed. The thread tooth can be accommodated in the thread gap in order to form a thread engagement. The thread tooth is guided between the two internal thread teeth. The internal thread teeth contact the two tooth flanks of the thread tooth. The axially measured gap width of the thread gap corresponds to the tooth width of the thread tooth of the threaded spindle.

In the aforementioned embodiment, it is advantageous that the tooth width of the thread tooth widens in a wedge shape at the transition between the first thread section with a smaller pitch and the second thread section with a larger pitch the tooth width increases continuously until it fills the gap in the thread with play. At the transition between the two thread sections, at least one internal thread tooth is preferably always in contact on one side with a tooth flank of the thread groove of the first thread section, until the transition area is completely accommodated in the thread gap and the wider thread tooth is guided in the thread gap. As a result, a continuous, constantly differentiable increase in the thread pitch from the first pitch to the second pitch can be implemented.

It is possible that a backlash between the internal thread and the external thread in the first thread section is different from the second thread section. Thread friction can be reduced by increasing tooth flank play. The backlash in the thread section with a smaller pitch can preferably be smaller than in the thread section with a larger pitch. The adjustment accuracy and the rigidity can be increased by a lower backlash, which is advantageous for the adjustment in the operating area with the smaller slope. A greater backlash allows easier adjustability due to the lower friction, which is advantageous for faster adjustment for stowage by means of a relatively low drive power. The practical implementation can advantageously take place on an internal thread tooth with two pairs of flanks, with one pair of flanks, preferably for the greater pitch, having a larger thread or flank play with respect to the external thread.

As a further development, it is possible for the tooth flanks of the internal thread and the external thread to be prestressed against one another in at least one of the thread sections. A preload can be generated, for example, by spring elements that are formed on a thread tooth or are integrated, and elastically press the contact surfaces on the thread flanks against one another with a preload force. It is advantageous that the thread play can be elastically brought to zero. Preferably, the preload may be provided in a thread portion with a smaller pitch, and in the thread portion with a larger pitch, the preload may be smaller or omitted.

Provision can advantageously be made for the thread to be self-locking in one of the thread sections. Due to the self-locking feature, the thread does not slip, even under high axial loads. This can advantageously be provided in the threaded section with a smaller pitch in order to enable safe and resilient positioning in the operating position.

It is possible that the thread is not self-locking in one of the threaded sections. This can be provided, for example, in the threaded section with a larger pitch. One advantage is that in an emergency, if the adjustment drive fails, an emergency adjustment into the stowed position is made possible by using a sufficiently large axial force.

It is conceivable and possible that not only two, but also additional threaded sections are provided, which have one of the two thread pitches according to the invention or also have a pitch that differs from the first and second pitch. For example, smaller thread pitches can be provided at the beginning and end of a larger thread pitch. As a result, a thread section with a smaller pitch can be provided in the extended operating or operating area and also in the stowage area. As a result, for example, a play-free fixation in the stowed position can take place with greater adjustment force than in the case of quick adjustment, for example for latching in the stowed position.

An advantageous embodiment can provide that the external thread has a plastic. The external thread can be formed at least partially, preferably in the area of the thread tooth, from a plastic, for example by overmoulding or coating with a thermoplastic polymer. Favorable sliding properties can be realized by a plastic in a material pairing with a metal or another plastic, as a result of which a smooth and low-backlash adjustment is made possible. A threaded spindle and/or a spindle nut can be efficiently manufactured in whole or in part from plastic, for example by injection molding.

It is preferred that the spindle drive can be driven by a motor. This can be done by providing a motorized drive unit which is designed to drive the threaded spindle and the spindle nut in rotation relative to one another. In a manner known per se, the drive unit can have an electric motor which is connected to the spindle nut or the threaded spindle in terms of drive, optionally via a gear, for the rotary drive.

In a steering column for a motor vehicle, with a support unit which can be attached to a vehicle body and by which an actuating unit is held, in which a steering input means is mounted, and with an adjusting drive which has a threaded spindle which engages with an external thread in a spindle nut , And includes a drive unit that is connected to the threaded spindle or the spindle nut in such a way coupled so that the threaded spindle and the spindle nut can be driven to rotate relative to one another, with the adjusting drive being connected to the support unit or the adjusting unit, the invention provides that the adjusting drive is designed according to one of the previously described embodiments or combinations thereof.

A steering spindle, which is rotatably mounted in the actuating unit and to which a steering wheel can be attached as a manual steering handle, can be provided as the steering input means, for example.

To achieve a longitudinal adjustment of the steering column in the direction of the longitudinal axis, an adjustment drive according to the invention can be arranged between the actuating unit and a casing unit, also known as a guide box or box rocker, which accommodates it in an axially longitudinally displaceable manner, which is connected to the support unit, and the threaded spindle axis is essentially parallel to the longitudinal axis can be aligned. For longitudinal adjustment, the adjustment drive can also be arranged between tubular casings of the adjustment unit that are telescopically adjustable relative to one another in the longitudinal direction.

To adjust the height, an adjustment drive can be arranged between the support unit and an adjusting unit mounted thereon so that it can be adjusted in height, or a casing unit in which the adjusting unit is accommodated.

An energy absorption device can preferably be effectively arranged between the support unit and the actuating unit, which plastically deforms an energy absorption element, for example a bending wire, a tear-off tab or the like, when the actuating unit is displaced relative to the support unit due to an accident. This offers the advantage of controlled braking and a reduction in the risk of injury in the event of a vehicle frontal impact.

A motorized longitudinal and vertical adjustment can be designed individually or in combination on a steering column.

character list

• 1 eine schematische perspektivische Ansicht einer erfindungsgemäßen Lenksäule,
• 2 eine weitere perspektivische Ansicht der erfindungsgemäßen Lenksäule gemäß 1 aus einem anderen Betrachtungswinkel,
• 3 einen erfindungsgemäßen Verstellantrieb in einer schematischen perspektivischen Ansicht,
• 4 den Verstellantrieb gemäß 3 in einer schematischen, teilweise auseinandergezogenen Darstellung,
• 5 eine vergrößerte Detaildarstellung der Gewindespindel des Verstellantriebs gemäß 3 und 4 in einem ersten Verstellzustand,
• 6 eine schematische Detailansicht wie in 5 in einem zweiten Verstellzustand,
• 7 eine schematische Detailansicht wie in 5 in einem dritten Verstellzustand,
• 8 eine zweite Ausführungsform eines erfindungsgemäßen Verstellantrieb in einer teilweisen perspektivischen Ansicht,
• 9 eine Detailansicht der Gewindespindel aus 8,
• 10 eine Spindelmutter in einer schematischen perspektivischen Ansicht,
• 11 ein schematisches Verstellgeschwindigkeits-(Steigungs-)Diagramm für einen erfindungsgemäßen Verstellantrieb.

Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. Show in detail:

• 1 a schematic perspective view of a steering column according to the invention,
• 2 a further perspective view of the steering column according to the invention 1 from a different perspective,
• 3 an adjustment drive according to the invention in a schematic perspective view,
• 4 according to the adjustment drive 3 in a schematic, partially exploded view,
• 5 an enlarged detailed view of the threaded spindle of the adjusting drive according to FIG 3 and 4 in a first adjustment state,
• 6 a schematic detail view as in 5 in a second adjustment state,
• 7 a schematic detail view as in 5 in a third adjustment state,
• 8th a second embodiment of an adjustment drive according to the invention in a partial perspective view,
• 9 a detailed view of the threaded spindle 8th ,
• 10 a spindle nut in a schematic perspective view,
• 11 a schematic adjustment speed (slope) diagram for an adjustment drive according to the invention.

Embodiments of the invention

In the various figures, the same parts are always provided with the same reference symbols and are therefore usually named or mentioned only once.

1 shows a steering column 1 according to the invention in a schematic perspective view from the top right at an angle to the rear end, based on the direction of travel of a vehicle, not shown, where a steering wheel, not shown here, is held in the operating area. 2 shows the steering column 1 in a view from the opposite side, ie seen from the top right.

The steering column 1 includes a support unit 2, which is designed as a console that has fastening means 21 in the form of fastening bores, which are used for attachment to a vehicle body, not shown. An actuating unit 3 is held by the support unit 2 and is accommodated in a casing unit 4--also referred to as a guide box or box rocker.

The actuating unit 3 has a casing tube 31 in which a steering spindle 32 is mounted so as to be rotatable about a longitudinal axis L, which extends axially in the longitudinal direction, ie in the direction of the longitudinal axis L. At the rear end of the steering shaft 32 is a fastener supply section 33 is formed, on which a steering wheel, not shown, can be attached.

The adjusting unit 3 is accommodated in the jacket unit 4 so that it can be displaced telescopically in the direction of the longitudinal axis L in order to implement a longitudinal adjustment in order to be able to position the steering wheel connected to the steering spindle 32 back and forth in the longitudinal direction relative to the support unit 2, as indicated by the double arrow parallel to the longitudinal axis L is indicated.

The casing unit 4 is mounted in a pivot bearing 22 on the support unit 2 such that it can pivot about a horizontal pivot axis 20 lying transversely to the longitudinal axis L. In the rear area, the jacket unit 4 is connected to the support unit 2 via an adjusting lever 41 . By rotating the adjusting lever 41 by means of an actuator 6 shown (see 2 ) the shell unit 4 can be pivoted relative to the support unit 2 about the pivot axis 20, which is horizontal in the installed state, whereby an adjustment of a steering wheel attached to the fastening section 33 can be carried out in the vertical direction H, which is indicated by the double arrow.

A first adjusting drive 5 is designed according to the invention and is used for the longitudinal adjustment of the adjusting unit 3 relative to the jacket unit 4 in the direction of the longitudinal axis L. The adjusting drive 5 has a spindle drive has a threaded spindle 7, which is screwed with its external thread into the corresponding internal thread of a spindle nut 8 in threaded engagement is.

The threaded spindle 7 has a spindle axis G, which runs parallel to the longitudinal axis L essentially.

The spindle nut 8 is rotatably mounted about the spindle axis G in a bearing housing 53 which is fixedly connected to the shell unit 4 . In the direction of the axis G, the spindle nut 8 is supported axially on the casing unit 4 via the bearing housing 53 . The adjustment drive 5 is accordingly a so-called immersion spindle drive.

The threaded spindle 7 is connected to the actuating unit 3 by a fastening element 54 formed at its rear end via a transmission element 34, namely fixed in the direction of the spindle axis G or the longitudinal axis L and fixed with respect to rotation about the spindle axis G. By the rotatingly drivable spindle nut 8 and the threaded spindle 7, which is stationary with respect to rotation, a so-called immersion spindle drive is realized.

The transmission element 34 extends from the actuating unit 3 through a slit-shaped passage opening 42 in the jacket unit 4. To adjust the steering column 1 in the longitudinal direction, the transmission element 34 can be moved freely in the passage opening 42 in the longitudinal direction.

The adjusting drive 5 has an electric motor 55 (drive motor) by which the spindle nut 8 can be driven in rotation relative to the spindle axis G relative to the fixed threaded spindle 7 . As a result - depending on the direction of rotation of motor 55 - the threaded spindle 7 can be displaced translationally in the direction of the spindle axis G relative to the spindle nut 8, so that the actuating unit 3 connected to the threaded spindle 7 relative to the jacket unit 4 connected to the spindle nut 8 in the direction of the Longitudinal axis L is adjusted.

In 2 , which is a perspective view of the steering column 1 from FIG 1 shows the rear side, it can be seen how a second adjustment drive 6 is attached to the steering column 1 for adjustment in the vertical direction H. This adjustment drive 6 includes a spindle nut 61, in which a threaded spindle 62 engages. The threaded spindle 62 is rotatably mounted about the axis K in a bearing housing 63, which is fastened to the casing unit 4 and supported axially on the casing unit 4, and can be driven by an electric motor 65 to rotate about the axis G in both directions of rotation. Accordingly, the adjustment drive 6 is a so-called rotary spindle drive.

The spindle nut 61, which can be made of plastic or a non-ferrous metal such as brass or the like, is attached to one end of the two-armed adjusting lever 41, which is fixed with respect to rotation about the axis K, and which is mounted on the support unit 2 so that it can rotate about a pivot bearing 22. and the other arm of which is connected to the jacket unit 4 at the other end.

By rotating the threaded spindle 61 - depending on the direction of rotation of the drive motor 65 - the spindle nut 61 can be displaced translationally in the direction of the K axis relative to the threaded spindle 52, so that the casing unit 4, which is connected to the spindle nut 61 via the adjusting lever 41, together with the adjusting device accommodated therein 3 can be adjusted up or down relative to the support unit 2 in the vertical direction H, as indicated by the double arrow.

The threaded spindle 61 can be designed analogously to the threaded spindle 7 according to the invention, and accordingly the spindle nut 61 analogous to the spindle nut 8.

3 and 4 show the adjustment drive 5 schematically isolated in different views ten, whereby 4 shows a schematic exploded view.

The threaded spindle 7 engages in the spindle nut 8 , which can be driven to rotate about the spindle axis G by the motor 55 . For this purpose, a worm gear is provided, which comprises a worm 56 mounted on the motor shaft, which is in gear engagement with a worm wheel 57 connected coaxially to the spindle nut 8 . Alternatively, other types of transmission are also possible, for example spur gears or belt drives.

The worm wheel 57 can, for example, be at least partially made of a plastic and be injection molded onto the spindle nut 8 . The spindle nut 8 can be made entirely or partially from a metallic material and/or a plastic.

The threaded spindle 7 has a first threaded section 71 and a second threaded section 72 axially adjoining it. Both threaded sections 71 and 72 form a continuous external thread that can be screwed into the spindle nut 8 .

The spindle thread is single-start in the example shown. A single thread tooth 73 is continuously formed across the two thread portions 71 and 72 . Between the thread turns, the thread tooth 73 with its tooth flanks 730 delimits a thread groove 74 which also goes through the two thread sections 71 and 72 .

In the first threaded section 71, which is partially enlarged in 5 is shown, the spindle thread has a first pitch P1 (thread pitch), the value of which results from the sum of the tooth width of the thread tooth 73 and the groove width of the thread groove 74, each measured axially in the direction of the spindle axis G.

In 7 the second threaded section 72 is shown enlarged in detail, analogously to the representation of the first threaded section 71 in 5 . The spindle thread in the second thread portion has a second pitch P2 that is greater than the first pitch P1. The value of the second pitch P2 is also the sum of the tooth width 731 of the thread tooth 73 and the groove width 741 of the thread groove 74, as in FIG 7 drawn in, whereby in the example shown the tooth width and the groove width are larger than in the first thread section 71.

The spindle nut 8 has at least one segment-shaped internal thread tooth 81, which is arranged in the threaded bore as an internal thread segment or toothed segment, directed radially inwards towards the spindle axis G, as shown in FIG 10 can be seen, in which a spindle nut 8 is shown separately in a schematic perspective view. This is designed in such a way that it can be brought into threaded engagement with both threaded sections 71 and 72 .

In the 5 , 6 and 7 the internal thread tooth 81 is shown cut in the circumferential direction in the radius of the tooth crest of the thread tooth 72 (indicated by hatching).

In 5 is the internally threaded tooth with the thread groove 74 in the first threaded portion 71 in threaded engagement. For this purpose, the internal thread tooth 81 has a first pair of tooth flanks consisting of two first tooth flanks 82 lying opposite one another. As in 5 As can be seen, the first tooth flanks 82 make contact with the tooth flanks 730 of the thread tooth 73 in the first thread section 71. The tooth flank spacing of the first tooth flanks 82 essentially corresponds to the groove width of the thread groove 74 in the first thread section 71 minus a predetermined thread play.

7 shows the thread tooth 81 in a representation analogous to FIG 5 , this time in threaded engagement with the second threaded section 72. A second tooth flank pair with the second tooth flanks 83 contacts the tooth flank 730 of the thread tooth 73, the tooth flank spacing of the second tooth flanks 83 being greater than the tooth flank spacing of the first tooth flanks 82. The tooth flank spacing corresponds to the second Tooth flanks 83 substantially relative to the first threaded portion 71 larger groove width of the thread groove 74 in the second threaded portion 71, minus a predetermined thread play.

The first tooth flanks 82 are inclined at the first pitch angle of the first pitch of the first thread section 71 relative to the longitudinal axis L, and the second tooth flanks 83 are inclined at the second pitch angle of the second pitch of the second thread section 72.

6 shows the internal thread tooth 81 at the transition between the two threaded sections 71 and 72. On the side facing the first threaded section 71 - on the left in the drawing - the one first tooth flank 82 rests against the tooth flank 730 in the area of the first threaded section 71, and the second tooth flanks 83 contact the tooth flank 730 in the area of the second thread section 72.

Based on the situation of 6 moves the internal thread tooth 81 nei a rela tive rotation in one direction of rotation in the direction of the first threaded portion 71 in accordance with an adjustment 5 , and with an opposite rotation into an adjustment state in the area of the second threaded section as in 7 .

If the speed of the motor 55 remains the same, the change in the adjustment speed changes automatically during the transition according to FIG 6 .

In the 8th and 9 a second embodiment of a spindle drive according to the invention is shown, which also has a first threaded section 71 with a smaller pitch and a second threaded section 72 with a relatively larger pitch. In comparison to the first embodiment, the groove width 741 of the thread groove 74 in the area of the second thread section 72 is greater than the tooth width 731 of the thread tooth 73. There, its tooth width 731 of the thread tooth 73 is greater than in the first thread area 71, and it can also be formed into the tooth head Have groove 75. This can be advantageous for producing the thread in plastic injection molding. In addition, the thread tooth 73 can be designed to be spring-elastic through the groove 75 transversely to its extent, ie also in the direction of its tooth width 731 .

The operation of the second embodiment differs from that shown in FIGS 3 until 7 described first embodiment with regard to the thread engagement in the second threaded portion 72 with the larger pitch P2.

In this case, a spindle nut 8 according to 10 be used. This has at least two segment-shaped internal thread teeth 81 which are offset in the circumferential direction. A free thread gap 84 is formed between each two internal thread teeth 81 . The gap width of this thread gap 84, measured axially, corresponds to the tooth width 731 of the thread tooth of the threaded spindle 7 in accordance with 7 and 8th .

In the first thread section 71 with the smaller pitch P1, the internal thread teeth 81 engage in the thread groove 74 and thereby contact the two opposing tooth flanks 730.

In the second thread section 72, the thread tooth 73 engages in the thread gap 84 between two internal thread teeth 81 and is thus guided between them. In this case, unlike in the first embodiment, a pair of tooth flanks does not rest on both sides of the thread groove 74 from the inside, but the tooth flanks 83 of the two internal thread teeth 81, between which the thread tooth 73 runs, rest on the two tooth flanks 730 of this thread tooth 73 from the outside.

It is advantageous that the thread tooth 73, whose tooth width 731 at the transition between the first threaded section 71 to the second threaded section 72 - in 9 from left to right - is widened in a wedge shape in the transition region 76, and is introduced continuously and without a stop into the thread gap 84 between the two internal thread teeth. Until the transition area 76 is completely accommodated in the thread gap 84, at least one internal thread tooth 81 is in contact on one side with a tooth flank 730 of the thread groove 84 of the first thread section 71. This allows a continuous, constantly differentiable increase in the thread pitch from the first pitch P1 to the second Pitch P2 can be realized.

The continuously differentiable transition of the pitch P in a relative rotation between two adjacent threads n and n+1 is shown schematically in the diagram in FIG 11 shown. This enables a continuous, jerk-free transition between the two thread pitches P1 and P2, and correspondingly a gentle change in the adjustment speed in the form of an acceleration or in the form of a negative acceleration, depending on the direction of rotation of the spindle nut.

The groove 75 allows the thread tooth 73 to be elastic in itself, so that its thread flanks 730 are elastically pretensioned with the spring force against the thread flanks 83 of the internal thread teeth 81 .

Reference List

1

steering column

2

carrying unit

20

pivot axis

21

fasteners

22, 23

swivel bearing

3

actuator

31

casing pipe

32

steering spindle

33

attachment section

34

transmission element

4

sheath unit

41

lever

42

passage opening

5, 6

adjustment drive

61

spindle nut

62

lead screw

53, 63

bearing housing

54

fastener

55, 65

engine

56

snail

57

worm wheel.

7

lead screw

71

first thread section

72

second thread section

73

thread tooth

730

tooth flank

731

tooth width

74

thread groove

741

groove width

75

groove

76

transition area

8th

spindle nut

81

internal thread tooth

82

first tooth flank

83

second tooth flank

84

thread gap

L

longitudinal axis

H

height direction

G, K

Spindle axis (threaded spindle axis)

P1, P2

pitch

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014103879 A1 [0006]

Claims (15)

Adjustment drive (1) for a steering column of a motor vehicle, with a spindle drive comprising a threaded spindle (7) with an external thread (71, 72) which engages in an internal thread (81) of a spindle nut (8), the external thread (71, 72) has a continuously circumferential threaded tooth (73) and a threaded groove (74), and wherein the threaded spindle (7) can be driven in rotation relative to the spindle nut (9), characterized in that the external thread (71, 72) has a first threaded section (71) with a first thread pitch (P1) and a second thread section (72) with a second thread pitch (P2) different from the first thread pitch (P1). adjustment drive claim 1 , characterized in that the second thread pitch (P2) is greater than the first thread pitch (P1). Adjustment drive according to one of the preceding claims, characterized in that the pitch ratio between the second thread pitch (P2) and the first thread pitch (P1) is greater than 1.5:1. Adjustment drive according to one of the preceding claims, characterized in that the pitch ratio between the second thread pitch (P2) and the first thread pitch (P1) is less than 20:1. Adjusting drive according to one of the preceding claims, characterized in that the pitch ratio between the second thread pitch (P2) and the first thread pitch (P1) is 10:1. Adjustment drive according to one of the preceding claims, characterized in that the internal thread has at least one internal thread tooth (81) which can be brought into threaded engagement with the external thread (71, 72) in the first threaded section (71) and the second threaded section (72). adjustment drive claim 6 , characterized in that the internally threaded tooth has two pairs of flanks (82, 83), a first pair of flanks (82) being threadably engageable with the thread groove (74) in the first threaded section (71), and a second pair of flanks (83) with the Threaded groove (74) in the second threaded portion (72) can be brought into threaded engagement. Adjustment drive according to one of the preceding Claims 6 until 7 , characterized in that a contact area between the female thread and the male thread in the first thread portion (71) is different from the second thread portion (72). Adjusting drive according to one of the preceding claims, characterized in that a backlash between the internal thread (71, 72) and the external thread (81) in the first threaded section (71) is different from the second threaded section (72). Adjusting drive according to one of the preceding claims, characterized in that the tooth flanks of the internal thread (71, 72) and external thread (81) are prestressed against one another in at least one of the thread sections (71, 72). Adjusting drive according to one of the preceding claims, characterized in that the thread in one of the thread sections (71, 72) is designed to be self-locking. Adjustment drive according to one of the preceding claims, characterized in that the thread in one of the thread sections (71, 72) is not self-locking. Adjusting drive according to one of the preceding claims, characterized in that the external thread (71, 72) has a plastic. Adjustment drive according to one of the preceding claims, characterized in that a motor drive unit (55, 65) is provided which is designed to drive the threaded spindle (7) and the spindle nut (8) in rotation relative to one another. Steering column (1) for a motor vehicle, with a support unit (2) which can be attached to a vehicle body and by which an actuating unit (3) is held, in which a steering input means (32) is mounted, and with an adjustment drive ( 5, 6), which comprises a threaded spindle (7, 62) which engages in a spindle nut (8, 61) with an external thread (71, 72), and a drive unit (55, 65) which is connected to the threaded spindle (7, 62) or the spindle nut (8, 62) is coupled in such a way that the threaded spindle (7, 62) and the spindle nut (8, 61) can be driven in rotation relative to one another, the adjustment drive (5, 6) being connected to the support unit (2) or the actuating unit (3) is connected, marked thereby characterized in that the adjusting drive (5, 6) is designed according to one of Claims 1 until 14 .

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