DE102021213456A1 - Spindle drive and method for operating such - Google Patents

Abstract

The invention relates to a spindle drive (10) for adjusting a moving part in a motor vehicle at different adjusting speeds, and a method for operating such a spindle drive (10), with a spindle (12) driven by an electric motor (20) and having a spindle thread (14 ) having a first axial spindle area (21) and a second axial spindle area (22), wherein the first axial spindle area (21) has a first thread pitch (31) which, with a first spindle nut (41), has a corresponding first nut pitch (51) meshes, and the second axial spindle area (22) has a second thread pitch (32) which meshes with a second spindle nut (42) with a corresponding second nut pitch (52), the first and the second spindle nut (41, 42) having the same Speed of the electric motor (20) provide different adjustment speeds.

Description

State of the art

The invention relates to a spindle drive and a method for operating such a drive according to the species of the independent claims.

With the DE 10 2016 203 639 A1 a spindle drive has become known which is used as part of a comfort drive for seat adjustment in a motor vehicle. This includes a drive motor that rotates a spindle about its longitudinal axis. A spindle nut is arranged on a spindle thread of the spindle, which in turn is at least indirectly connected to the element to be adjusted, in particular the seat. When the spindle rotates about its axis of rotation, the spindle nut moves in the longitudinal direction of the spindle or along the axis of rotation of the spindle due to its rotationally fixed position in relation to the axis of rotation of the spindle and thus moves the seat. With such a spindle drive, it is very difficult due to the design on the one hand to achieve high adjustment speeds of the seat and at the same time to implement reliable self-locking to block the adjustment movement.

The EP 1 109 695 B1 shows a drive device for adjusting parts of a motor vehicle seat, with a single electric drive motor, which drives two auxiliary shafts by means of a first worm gear, with a clutch unit having four clutches, which couple the drive motor to various output elements of the output unit independently of one another via further worm gears. However, the efficiency of such a gear arrangement with at least two consecutive worm gears is relatively low, so that quick adjustment is difficult to achieve with it.

These disadvantages are to be overcome with the solution according to the invention.

Disclosure of Invention

The spindle drive according to the invention and the method for producing such with the features of the independent claims have the advantage that with a single electric motor of a spindle drive without additional gear stages, different adjustment speeds for adjusting a moving part in the motor vehicle can be made available. Sections with different thread pitches can be formed on the spindle, so that with the different adjustment speeds, spindle nuts with different self-locking can be realized at the same time, which advantageously allows the part to be adjusted to be reliably blocked after the adjustment process.

The measures listed in the subclaims result in advantageous developments and improvements of the features specified in the dependent claims. The first spindle area with the corresponding first spindle nut is preferably designed without self-locking if possible, so that a very high level of efficiency can be achieved for rapid adjustment. The second spindle area with the corresponding second spindle nut, on the other hand, is preferably deliberately designed with self-locking so that when this second spindle nut is coupled in, the part to be adjusted is protected via the self-locking spindle area from unwanted adjustment by external forces. A single rotary spindle can thus provide a self-locking drive or, alternatively, a more efficient drive without self-locking. As a result, higher adjustment speeds can be achieved with a certain available engine power, as is necessary, for example, in a pre-crash situation or for the driver to take over control of the vehicle in good time during automated driving. A "self-locking spindle adjustment" is considered to be an application with a typical load profile, so that the part to be adjusted remains in its position even with normal load changes. Depending on the definition of "self-locking", two self-locking or two non-self-locking spindle areas can also be designed with the corresponding spindle nuts.

So that the two different adjustment speeds can be picked up independently from the spindle, the spindle nuts are each engaged or disengaged by their own coupling element. This makes it possible to control which of the two spindle nuts transmits the torque from the spindle to the corresponding transmission part and its subsequent mechanics.

If the second thread pitch is self-locking with the corresponding second threaded spindle, the part to be adjusted remains reliably positioned at this point after the adjustment process, without additional safety measures having to be taken. The second spindle nut can simply remain engaged after the adjustment process in order to reliably block the part to be adjusted.

If, on the other hand, the part to be adjusted is adjusted at high adjustment speed without self-locking using the first spindle nut, it is necessary for the first spindle nut to be coupled into the first spindle area with self-locking after the adjustment process has been completed, in order to block the part to be adjusted. As a result, the first spindle nut with the self-locking always serves to secure the position of the part to be adjusted when it is not being adjusted. Thus, with the second spindle area with the low adjustment speed, a blocking device for the part to be adjusted can always be implemented at the same time.

If higher holding forces are required for the part to be adjusted in the blocked state, for example in a crash situation, the first spindle nut can also be coupled into the first spindle area in addition to the second spindle nut at the same time by means of its coupling element. As a result, both spindle nuts with different thread pitches are in the power flow with the rotary spindle at the same time, whereby the two spindle sections are clamped against each other when a force is applied and thus provide a higher holding torque for the part to be adjusted.

The clutch elements can preferably be designed as a multi-plate clutch or as a claw clutch, which can be brought into engagement with the spindle nut by means of an electric actuator. Depending on the requirement, the transmission element is connected either with a force fit or with a form fit with the corresponding spindle nut in order to transmit the output element of the spindle to the part to be adjusted. The actuator can have an electromagnetic lifting magnet, for example, which is reset again, for example, by means of a mechanical spring force. As a result, the coupling elements can be designed in such a way that a defined emergency mode is always adopted in the event of a power failure, for example. In particular, in the event of a power failure, the second spindle nut can be brought into engagement with the self-locking spindle area in order to block the part to be adjusted.

In order to transmit the output torque from the spindle via the first or the second spindle nut to the part to be adjusted, corresponding transmission parts are coupled in a torque-proof manner to the first spindle nut or to the second spindle nut by means of the coupling elements. As a result, the transmission part is adjusted linearly on the spindle together with the corresponding spindle nut, without performing a rotation. A mechanism is fastened to the transmission part, which mechanism transmits the linear adjustment movement of the transmission part to the part to be adjusted. The part to be adjusted can be adjusted directly with the same linear movement, or the mechanism can be converted into a pivoting or tilting or rotary movement of the part to be adjusted.

The transmission part can advantageously be designed as a ring element, which is mounted on a cylinder surface of the spindle nut. For coupling and decoupling, the transmission part can be moved axially on the cylinder along the spindle axis. To engage the transmission part, it is pressed axially in a non-positive or positive manner, for example against an axial collar of the spindle nut, in order to transmit the output element of the spindle to the transmission part via the spindle nut. For decoupling, the transmission part is axially detached from the collar of the spindle nut, so that in particular the spindle nut rotates with the rotary spindle in the decoupled state and the transmission part remains non-rotatably relative to the spindle without the flow of force.

In order to adjust the part, one transmission part is engaged and operatively connected to the corresponding spindle nut, while the other transmission part is decoupled and rotatably mounted on the cylindrical surface of the other spindle nut. This spindle nut rotates with the spindle relative to the fixed transmission part. During the adjustment process of the part, the decoupled transmission part, together with the corresponding mechanism, can in particular move axially with the part to be adjusted in relation to the decoupled spindle nut.

The spindle is driven particularly favorably by the electric motor via a worm gear, with the rotor shaft of the electric motor having a worm which engages directly in a worm wheel which is fastened on the spindle in a rotationally fixed manner. The spindle lies at a free end against an axial stop of the gear housing for the worm gear. The worm wheel is preferably mounted radially directly in the gear housing and runs opposite the axial stop on a stop disk, which in turn is supported on the gear housing.

The second spindle area preferably has a smaller pitch, which is in the range of 2 to 3 mm per revolution of a thread turn. The first spindle area for faster adjustment has a thread pitch that is preferably two to three times higher than the thread pitch of the second spindle area, and is about 5 to 7 mm per revolution of a continuous thread. As a result, a very high adjustment speed can be made available on the threaded spindle for a short period of time, which can be in the range from 80 to 150 mm per second.

With the spindle drive according to the invention, the moving part can alternatively be adjusted with two different adjustment speeds, which means that the use of only a single electric motor and only a single spindle with two different spindle areas can save considerable space, weight and costs.

If, after the end of an adjustment process, both spindle nuts are engaged simultaneously with the corresponding transmission parts, a locking device with particularly high holding forces can be made available for the part to be adjusted. As a result, both a very high adjustment speed without self-locking and, at the same time, a very reliable blocking of the part to be adjusted after the adjustment process can be realized by means of a single spindle drive.

The spindle drive according to the invention is particularly suitable for use in a steering column adjustment or for a seat adjustment in a motor vehicle. The steering wheel can be adjusted lengthwise and crosswise to the steering column with the spindle drive. Thus, over the entire service life, even with large temperature fluctuations, different adjustment speeds and also a locking device for the steering column can be provided by the spindle drive. The spindle nut with the transmission part is preferably coupled to the steering column via the mechanism and the spindle is preferably fastened to the body via the drive motor. In order to transmit the adjustment forces to the part to be adjusted, two opposing radial extensions are preferably formed on the radially outer circumference of the transmission parts. On these extensions are preferably rotatably mounted as a mechanism links that transmit the adjustment to the part to be adjusted.

Description of the drawings

• 1 eine Ausführung eines erfindungsgemäßen Spindelantriebs.

Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and from the drawing. Show it:

• 1 an embodiment of a spindle drive according to the invention.

In the 1 a spindle drive 10 is shown, which is used as part of a comfort drive in a motor vehicle for adjusting a moving part. The moving part can be, for example, a steering column, or a seat or a seat component. How out 1 As can be seen, the spindle drive 10 comprises a drive motor 20 which, via an output element 86, drives a toothed element 84 which is arranged on a spindle 12 in a rotationally fixed manner. The spindle drive 10 has the spindle 12 with a spindle thread 14 which is divided into a first axial spindle area 21 and a second axial spindle area 22 . The first spindle area 21 has a first thread pitch 31 which is larger than a second thread pitch 32 of the second spindle area 22. A first spindle nut 41 is arranged on the first spindle area 21 and can be rotated with a first nut pitch 51 into the first thread pitch 31 intervenes. A second spindle nut 42 is arranged on the second spindle region 22 and engages with a second nut pitch 52 rotatably in the second thread pitch 32 . Due to the larger first thread pitch 31, the first spindle nut 41 can move faster along the spindle axis 8 during the rotation of the spindle 12 than the second spindle nut 42 on the smaller spindle pitch 32 part are made available. For example, the rapid adjustment speed can be used to quickly move the part as a boarding aid or in a pre-crash situation or a "take control" situation during automated driving. The lower adjustment speed can be used for the normal operation of the comfort adjustment, in which the electric motor 12 can also be actuated in particular during longer continuous operation. In order to transmit the torque of the spindle 12 to the part to be adjusted, a transmission element 66 is arranged on the first and on the second spindle nut 41, 42, which transmits the adjusting torque to the part to be adjusted by means of a mechanism 67. The linear movement of the spindle nut 41, 42 can be transferred directly into a linear movement of the part. Alternatively, the linear movement of the spindle nut 41, 42 can also be converted into a pivoting, tilting, or rotating movement of the part by means of appropriately designed kinematics of the mechanism 67. To adjust the part, the first spindle nut 41 can optionally be operatively connected to the corresponding transmission part 66 by means of a first coupling element 61 . Alternatively, the second spindle nut 42 can be operatively connected to a corresponding transmission part 66 by means of a second coupling element 62 . Thus, by the single electric motor 20, which rotates the spindle 12 via a gear 80, by selectively actuating the first or the second coupling element 61, 62, the part can be adjusted at different adjustment speeds. In the preferred embodiment shown, the transmission part 66 is designed as a ring 65 which is arranged in an axially displaceable manner on a cylindrical surface 72 of the spindle nut 41, 42. In the uncoupled state, the transmission part 66 remains in a rotationally fixed position, while the spindle nut 41 , 42 rotates with the spindle 12 without being linearly adjusted along the spindle axis 8 . In the coupled state, the transmission part 66 is non-rotatably connected to the spindle nut 41, 42, as a result of which the spindle 12 rotates relative to the spindle nut 41, 42. As a result, the spindle nut 41, 42, together with the transmission part 66 connected thereto in a positive or non-positive manner, is linearly displaced in relation to the spindle 12 without rotating.

In 1 the first clutch element 61 on the left-hand side is designed schematically as a multi-plate clutch 59 . The ring 66 of the transmission part 66 rests axially in a non-positive manner on an annular collar 70 of the spindle nut 41 in the engaged state. The first coupling element 61 is actuated by an actuator 64 which displaces the transmission part 66 axially with respect to the first spindle nut 41 . For coupling, the transmission part 66 is pressed axially so strongly against the annular collar 70 that both remain non-rotatably connected to one another via a frictional connection. For decoupling, the transmission part 66 is detached axially from the annular collar 70 so that there is no longer a non-positive connection. In 1 on the right-hand side, the first coupling element 61 is alternatively shown schematically as a claw coupling 60 in which the transmission part 66 positively engages in the first spindle nut 41 along the spindle axis 8 . For this purpose, in particular the ring 65 and the annular collar 70 have a corresponding axial toothing in the direction of the spindle axis 8 . The actuator 64 has a lifting magnet, for example, which preferably detaches the transmission part 66 from the spindle nut 41 for decoupling. In contrast, the axial pressure for engaging the transmission part 66 can be effected, for example, by means of a spring force.

In 1 a second coupling element 62 is shown below for the second spindle nut 42 by way of example, in which the transmission part 66 is positively connected to the spindle nut 42 for coupling in the radial direction 7 . In particular, at least one locking bar 58 can be displaced in the radial direction 7 . For decoupling, the at least one locking bar 58 is pulled radially outwards, for example by an actuator 64. In the decoupled state, the transmission parts 66 can slide axially along the cylinder surface 72 of the spindle nuts 41, 42. The cylinder surface 72 can preferably be designed as an axial extension 68 of the spindle nut 41, 42, which extends from the annular collar 70 along the spindle axis 8. Alternatively, the cylinder surface 72 can also be formed over the entire axial length of the spindle nut 41, 42, in which case the positive or non-positive connection to the transmission part 66 takes place in the radial direction 7. The two coupling elements 61 and 62 can be actuated independently of one another, so that, in particular, only the first spindle nut 41 is operatively connected to the part for adjusting the part at a first adjustment speed, and only the second spindle nut is operatively connected to the part for adjusting the part at a second adjustment speed 42 is operatively connected to the part. In this case, for example, the mechanism 67 of the other, decoupled transmission part 66 can move along axially without power transmission on the cylinder surface 72 of the decoupled spindle nut 42, 41. To block the part, when the electric motor 20 is switched off, both coupling elements 61, 62 can preferably be engaged at the same time in order to create an operative connection of both spindle nuts 41, 42 with the part to be adjusted at the same time.

$${\gamma }_2=\text{arc tan}\left(\Delta \text{h}2/\text{Dm}\ast \mathrm{\pi }\right)$$

wobei Dm der mittlere Durchmesser des Spindelgewindes 14 der Spindel 20 darstellt. Bevorzugt liegt die erste Gewindesteigung 31 Δh1 / Dm*π des ersten Spindelbereichs 21 zwischen 0,05 und 0,15, und die zweite Gewindesteigung 32 Δh2 / Dm*TC des zweiten Spindelbereichs 22 zwischen 0,15 und 0,25. Insbesondere ist die erste Gewindesteigung 31 des ersten Spindelbereichs 21 um den Faktor 2 bis 3 größer als die zweite Gewindesteigung 32 des zweiten Spindelbereichs 22. Werden mehrgängige Spindelbereiche 21, 22 verwendet, wird die Gewindesteigung 31, 32 aus einer vollständigen Umdrehung einer bestimmten druchgängigen Gewindefurche ermittelt. Der mittlere Durchmesser des Spindelgewindes 14 Dm liegt typischer Weise im Bereich zwischen 8 und 13 mm.The spindle 12 - and correspondingly the spindle nuts 41, 42 - are preferably single-threaded, so that a pitch angle γ of the thread pitches 31, 32 (and that of the nut pitch 51, 52 of the spindle nuts 41, 42) is due to the path difference Δh of two axially adjacent thread turns 33 results. The pitch angle γ of the thread pitches 31, 32 is therefore calculated according to $$g_1=\text{arctan}\left(\Delta \text{H}1/\text{Dm}\ast \mathrm{\pi }\right)$$

$$g_2=\text{arctan}\left(\Delta \text{H}2/\text{Dm}\ast \mathrm{\pi }\right)$$

where Dm represents the mean diameter of the spindle threads 14 of the spindle 20 . The first thread pitch 31 Δh1/Dm*π of the first spindle area 21 is preferably between 0.05 and 0.15, and the second thread pitch 32 Δh2/Dm*TC of the second spindle area 22 is preferably between 0.15 and 0.25. In particular, the first thread pitch 31 of the first spindle area 21 is greater by a factor of 2 to 3 than the second thread pitch 32 of the second spindle area 22. If multiple-start spindle areas 21, 22 are used, the thread pitch 31, 32 is determined from a complete revolution of a specific continuous thread groove . The mean diameter of the spindle thread 14 Dm is typically in the range between 8 and 13 mm.

In the exemplary embodiment, the spindle 12 is driven via a worm gear 80 . In this case, on a rotor shaft 88 of the electric motor 20 a worm 86 is arranged as the output element, which meshes with a toothed element designed as a worm wheel 84, which is arranged on the spindle 12 in a rotationally fixed manner. For example, the worm wheel 84 is sprayed onto the spindle 12 together with the radial bearing areas 85 using plastic. The worm wheel 84 is mounted radially with the radial bearing areas 85 in the transmission housing 16 . The spindle 12 runs axially at a first end 81 against the axial stop 82 fixed to the housing. A metal ball 83 , for example, is inserted at the first end 81 and is supported directly on the axial stop 82 .

Furthermore, an annular collar 89 is formed on the worm wheel 84 , which is supported axially via an axial spring element 90 opposite the axial stop 82 on the transmission housing 16 . In particular, the annular collar 89 bears against a separately produced stop ring 87 which is pushed onto the worm wheel 84 via the radial bearing area 85 facing away from the first end 81 . The worm 86 is arranged, for example, transversely to the spindle 12 and can be mounted radially to the spindle 12 in the transmission housing 16 . For this purpose, the transmission housing 16 has a cover 18 which is joined radially to the spindle 12 . To mount the spindle drive 10, a bearing eyelet 19 is formed on the gear housing 16 and can be pushed rotatably onto a bearing bolt which is fixed to the body or to the part to be adjusted.

It should be noted that with regard to the exemplary embodiments shown in the figures and the description, a wide variety of possible combinations of the individual features are possible. The spindle drive 10 described can be altered or modified in many ways without departing from the spirit of the invention. The design of the coupling elements 61, 62 and the transmission parts 66 with the mechanisms 67 and the actuators 64 can be adapted to the requirements of the part to be adjusted. Likewise, the spindle nuts 41, 42 and their axial extensions 68 and their annular collars 70 can be varied accordingly. Instead of the worm gear 80, the spindle 12 can also be rotated with another gear arrangement. The inventive electric spindle drive 10 is particularly suitable for adjusting movable components in the motor vehicle, in particular for adjusting the steering column or seat components.

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 102016203639 A1 [0002]
• EP 1109695 B1 [0003]

Claims (14)

Spindle drive (10), in particular for adjusting a moving part in a motor vehicle at different adjustment speeds, with a spindle (12) driven by an electric motor (20) and having a spindle thread (14) with a first axial spindle area (21) and a second axial spindle area (22), wherein the first axial spindle area (21) has a first thread pitch (31) which meshes with a first spindle nut (41) of a corresponding first nut pitch (51), and the second axial spindle area (22) has a second thread pitch ( 32) which meshes with a second spindle nut (42) with a corresponding second nut pitch (52), the first and second spindle nuts (41, 42) providing different adjustment speeds at the same speed of the electric motor (20). Spindle drive (10) after claim 1 , characterized in that the first thread pitch (31), which meshes with the first spindle nut (41) with the first nut pitch (51), is designed without self-locking and has a greater pitch than the second thread pitch (32), which with of the second spindle nut (42) meshes with the second nut pitch (52). Spindle drive (10) after claim 1 or 2 , characterized in that a first and a second coupling element (61, 62) are arranged on the first and on the second threaded nut (41, 42), with the first or alternatively the second threaded nut (41 , 42) transmits the output torque to the part to be adjusted by means of the first or the second coupling element (61, 62). Spindle drive (10) according to one of the preceding claims, characterized in that the second thread pitch (32) with the smaller pitch is designed to be self-locking. Spindle drive (10) according to one of the preceding claims, characterized in that to block the part to be adjusted after it has been adjusted by means of the first threaded nut (41), the second, self-locking threaded nut (42) is then again connected to the spindle by means of the second coupling element (62). (12) is operatively connected. Spindle drive (10) according to one of the preceding claims, characterized in that in order to block the part to be adjusted after it has been adjusted, the first and the second coupling element (61, 62) are operatively connected at the same time to the first and the second threaded nut (41, 42), in order in particular to increase the resulting self-locking between the spindle (12) and the two threaded nuts (41, 42). Spindle drive (10) according to one of the preceding claims, characterized in that the first and/or the second coupling element (61, 62) is designed as a non-positive multi-plate clutch (59) or as a positive-locking claw clutch (60), and the first and/or the second clutch element (61, 62) is actuated by at least one actuator (64) in order to close or release the power flow for the torque transmission from the spindle (12). Spindle drive (10) according to one of the preceding claims, characterized in that the first and/or the second coupling element (61, 62) has a non-rotatably arranged transmission part (66) which, in the engaged state, is connected to the first and/or the second spindle nut ( 41, 42) is moved along the spindle axis (9) and is connected to the part to be adjusted by means of a mechanism (67) in order to adjust it. Spindle drive (10) according to one of the preceding claims, characterized in that at least one transmission part (66) is designed as a closed ring (65) which can be moved axially on an axial extension (68) of the first and/or the second spindle nut (41, 42) and, in the engaged state, rests axially on an annular collar (70) of the first and/or the second spindle nut (41, 42). Spindle drive (10) according to one of the preceding claims, characterized in that the first or the second spindle nut (41, 42) in the engaged state is non-positively or positively connected to the at least one transmission part (66) in a rotationally fixed manner, and the first or the second Spindle nut (41, 42) rotates with the spindle (12) in the decoupled state of the at least one transmission part (66) without transmitting a drive torque. Spindle drive (10) according to one of the preceding claims, characterized in that the spindle (12) is designed as a rotary spindle which is supported axially on a fixed stop (82), and the spindle (12) has a worm wheel (84) arranged in a rotationally fixed manner , into which engages a worm (86) driven by the electric motor (20). Spindle drive (10) according to one of the preceding claims, characterized in that a pitch of the second thread pitch (32) is in the range of 2.0 to 3.5 mm per revolution, and the first thread pitch (31) by a factor of 2 - 3 larger than the second thread pitch (32). Method for operating a spindle drive (10) for adjusting a movable part in a motor vehicle, in particular according to one of Claims 1 until 12 , characterized in that to adjust the part at a first adjustment speed, the part is coupled via a first spindle nut (41) to a first thread pitch (31) of the spindle (12), and to adjust the part at a second adjustment speed, the part is coupled via a second spindle nut (42) is coupled to a second thread pitch (32) of the same spindle (12), the spindle (12) being rotated by means of an electric drive (20). procedure after Claim 13 , characterized in that in order to block the part to be adjusted, at least the second thread pitch (32), which has a smaller pitch than the first thread pitch, (31) is coupled to the part to be adjusted via the second spindle nut (42) - and in particular at the same time the first thread pitch (31) is also coupled to the part to be adjusted via the first spindle nut (41) in order to increase the overall self-locking of the spindle drive (10).

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