DE102014117008A1 - spindle drive - Google Patents

Abstract

The invention relates to a spindle drive (1) for a closure element (2) of a motor vehicle, wherein a drive unit (3) and a drive spindle (3) downstream drive spindle spindle nut gear (6) with geometric spindle axis (7) for generating linear drive movements between two drive connections (8, 9) are provided, wherein the spindle spindle nut transmission (6) has a spindle (10) with a spindle external thread (11) and a spindle nut (12) with a spindle nut internal thread (13) which engage with one another by screwing ( 14) form. It is proposed that the screw engagement (14) has a compliance such that in case of overload, an axial load between spindle (10) and spindle nut (12) above a predetermined overload limit dissolves the screw engagement (14).

Description

The present invention relates to a spindle drive for a closure element of a motor vehicle according to the preamble of claim 1.

The term "closure element" is to be understood in the present case. It includes, for example, a tailgate, a trunk lid, a hood, a side door, a luggage compartment lid, a window, a lifting roof o. The like. A motor vehicle. Below is the scope of the motorized adjustment of a tailgate of a motor vehicle in the foreground.

The motorized adjustment of a tailgate o. The like. Has prevailed in recent years, especially in the field of combined motor vehicles. In addition to a reliable and quiet motorized adjustment, a high degree of robustness against malfunctions and operating errors plays an important role.

An example of an above malfunction is the failure of the supply voltage of the motor vehicle with the tailgate open. Here is an uncomplicated, manual adjustment of the tailgate to allow. An example of a faulty operation above, for example, in a manual adjustment of the tailgate during a motor adjustment, especially in a manual adjustment with excessive adjustment. Here it must be ensured that the drive train of the tailgate-associated drive does not suffer any damage.

A well-known drive ( DE 20 2008 016 929 U1 ), which is designed in a variant as a spindle drive and from which the invention proceeds, shows an electric drive unit and a drive unit downstream of the spindle spindle nut transmission. The powertrain of the drive is not self-locking, but equipped with an additional brake. This is on the one hand, a manual adjustment of the tailgate and on the other hand, a maintenance of the tailgate in intermediate positions guaranteed.

For the protection of the drive train against an excessively fast manual adjustment, the drive train in addition to the already existing drive components on an overload clutch, which may be constructed, for example in the manner of a friction clutch. This led to a safe protection of the drive train from a malfunction mentioned above. However, the design of the known drive with the additional coupling in view of the always limited in spindle drives space conditions a challenge.

The invention is based on the problem of designing the known drive and further develop such that an overload clutch in the drive train in a particularly compact and cost-effective manner can be realized.

The above problem is solved in a spindle drive according to the preamble of claim 1 by the features of the characterizing part of claim 1.

Essential is the fundamental consideration that the always provided for spindle drives screw engagement between the spindle and spindle nut well suited for the realization of an overload clutch, without having to connect a separate component in the drive train.

Specifically, it is proposed that the screw engagement between spindle and spindle nut has a compliance such that in case of overload, an axial load between spindle and spindle nut above a predetermined overload limit dissolves the screw engagement. By "axial load" is meant any kind of force action along the spindle axis between spindle and spindle nut. In this case, this force effect can also be a component of a force vector having other components in other directions, for example in the radial direction.

With the proposed overload clutch, the above overload clutch can be independent of the position of the spindle drive, so ensure the relative position between the spindle and spindle nut.

The compliance of the screw engagement can preferably be realized by a corresponding flexibility of the spindle and / or the spindle nut (claim 2). For both variants, the overload causes a deformation of the components involved in the screw engagement such that the screw engagement is at least temporarily resolved.

In the preferred, first alternative of claim 3, the resilience provided for the overload case is elastic, so that the overload case can be done without destroying it. In contrast, in a second alternative of claim 3, the resilience is provided plastically, so that at least a part of the screw engagement resolved by overloading can not be restored. In the second alternative, it is assumed that an overload case is followed by a workshop stay, in which the screw engagement is restored by the replacement of the respective, plastically deformed part. The former alternative on the other hand, as indicated above, it can be repeated depending on the design, so that it is also suitable for ensuring a normal operational manual adjustability of the closure element.

The intended for the overload compliance can go back to a resilient design of the material of the spindle or spindle nut according to claim 4, which allows a structurally particularly simple structure. However, the resulting life is subject to certain limitations.

A particularly preferred possibility for generating the intended for the overload case compliance is the subject of claim 5, wherein the spindle and / or spindle nut have at least two thread segments, which in particular by their arrangement show the required compliance. For this purpose, a spring arrangement according to claim 8 is provided in a further preferred embodiment, which acts on the above thread segments.

Particularly preferred embodiments of the spring arrangement are subject matter of claims 11 to 14. The use of helical compression springs according to claim 11 provides a cost-effective and reproducible mechanical bias of the thread segments, while embracing at least a portion of the spindle nut by the spring arrangement according to claims 12 and 13 a structurally simple and montetechnisch advantageous embodiment allows. With the particularly preferred embodiment according to claim 14, which provides a gear arrangement between the spring arrangement and threaded sections, the required biasing forces can be realized with inexpensive spring elements of the spring arrangement.

In a particularly preferred alternative of claim 15 it is provided that the above mechanical bias of the thread segments causes a braking of a rotation of the spindle relative to the spindle nut. This can be achieved with the proposed implementation of the overload function at the same time an above-mentioned, continuous braking of the drive train to keep the associated closure element in the case of a non-self-locking drive train in intermediate positions. The omission of an otherwise additionally existing brake results in a further increase in the compactness of the spindle drive.

In the following the invention will be explained in more detail with reference to a drawing illustrating only embodiments. In the drawing shows:

1 in a very schematic representation of the rear area of a motor vehicle with a tailgate, which is associated with a proposed, shown in a detailed view of the spindle drive,

2 in a perspective view, the screw engagement between the spindle and the spindle nut of the proposed spindle drive a) in the normal case and b) in case of overload,

3 various embodiments for the screw engagement of the spindle drive according to 1a) in an embodiment according to 2 with radially acting helical compression springs, b) in one embodiment with radially acting spring clip and c) in one embodiment with axially acting compression springs, and

4 the spindle drive according to 1 in a further embodiment.

The spindle drive shown in the drawing 1 serves the motorized adjustment of a closure element 2 of a motor vehicle. With regard to the further understanding of the term "closure element" may be made to the introductory part of the description. In the following, the invention will be described with reference to a closure element designed as a tailgate 2 explained, since the possibility of manual adjustment in motor tailgates always plays an important role.

The spindle drive is equipped with a here and preferably electric drive unit 3 equipped with an electric drive motor 4 and a drive motor 4 downstream intermediate gear 5 having. The drive unit 3 a total of drive technology downstream is a spindle-spindle nut transmission 6 with geometric spindle axis 7 for generating linear drive movements between two drive connections 8th . 9 , The spindle spindle nut transmission 6 has in a conventional manner a spindle 10 with spindle external thread 11 and a spindle nut 12 with spindle nut internal thread 13 on, a screw engagement with each other 14 form.

The spindle drive 1 is in the in 1 shown assembled state drivably with the closure element 2 coupled. The spindle drive takes over 1 the adjustment of the closure element 2 , here the tailgate, between the in 1 shown open position and a closed position, not shown. Depending on the application, an additional spring arrangement 15 be provided, which is the closure element 2 pushes into the open position. In the illustrated embodiments, such a spring arrangement 15 in the spindle drive 1 integrated.

At the in 1 shown and so far preferred embodiment are a total of two spindle drives 1 provided on two opposite edge regions of a flap opening 16 are arranged. In principle, however, it can also be provided that only one spindle drive 1 is provided, which at one of the edge regions of the flap opening 16 is arranged. In this case, any manual load on the tailgate 2 from a spindle drive 1 be recorded.

It is essential now that the screw engagement 14 between spindle 10 and spindle nut 12 has a compliance such that in case of overload, an axial load between the spindle 10 and spindle nut 12 above a predetermined overload limit the screw engagement 14 dissolves.

The screw engagement 14 Normally, the illustration shows 2a while the presentation according to 2 B the situation with just loosened screw engagement 14 shows. With dissolved screw engagement 14 it is the spindle nut 12 possible, along the spindle 10 to glide. This leads to a skipping of the spindle external thread 11 and the spindle nut internal thread 13 , so that a correspondingly linear adjustment of the two drive connections 8th . 9 to each other is possible without the spindle 10 rotates.

In the illustrated spindle drive 1 it is preferably a spindle drive with non-self-locking, so re-drivable drive train between the two drive terminals 8th . 9 , allowing manual adjustment of the closure element 2 under a drive back of the drive motor 4 is possible. With an excessively fast manual adjustment of the closure element 2 However, the above-mentioned overload occurs, so that the screw engagement 14 dissolves and the spindle nut 12 largely free from the spindle 10 is adjustable. This will result in excessively faster manual adjustment of the closure element 2 the drive train, moreover, protected against destruction.

Alternatively, it may be advantageous that the spindle drive 1 self-locking is designed. This means that the drive train between the two drive connections 8th . 9 is not designed to be repossessed. For a manual adjustment, a clutch separating the drive train is then even absolutely necessary. This clutch can be provided by the proposed overload clutch, by any manual adjustment of the closure element 2 an overload case mentioned above with resulting resolution of the screw engagement 14 generated.

It should be noted that the proposed solution to all possible structural variants of spindle drives 1 is applicable. 1 shows a spindle drive 1 in which a slender spindle 10 a much shorter spindle nut 12 penetrates. Here is the spindle nut 12 the compliance provided for the overload case. 4 on the other hand shows a squat spindle 10 , which is a much longer spindle nut 12 penetrates. Here it is preferable that the spindle 10 having the intended for the overload case compliance. In principle, it can also be provided that the intended for the overload case compliance both in the spindle 10 as well as in the spindle nut 12 of the spindle drive 1 is provided.

At the in 1 illustrated embodiment, the spindle external thread 11 and the spindle nut internal thread 13 designed such that one with respect to the spindle axis 7 axial load between spindle 10 and spindle nut 12 by the provided for the overload compliance to a widening of the inner cross section of the spindle nut 12 leads. This is best in a synopsis of 2a and 2 B refer to. At the in 4 However, it is shown that the spindle external thread 11 and spindle nut internal thread 13 are designed such that one with respect to the spindle axis 7 axial load between spindle 10 and spindle nut 12 by the flexibility provided for the overload case to compress the outer cross section of the spindle 10 leads. Basically, as indicated above, the widening of the inner cross section of the spindle nut 12 and compressing the outer cross section of the spindle 10 in case of overload also be combined with each other.

Here and preferably, the configuration of the spindle external thread 11 and the design of the spindle nut internal thread 13 cause of the above deformation of spindle 10 or spindle nut 12 , For this purpose, it is preferably provided that the spindle external thread 11 and / or the spindle nut internal thread 13 have a flank angle which is above 30 °. This results in an axial load between the spindle 10 and spindle nut 12 a wedge effect with resulting, based on the spindle axis 7 Radial forces that produce an above-mentioned deformation.

Preferably, the flexibility provided for the overload case is elastic, so that the screw engagement 14 restores after an overload due to elastic recovery. This is realized in the illustrated embodiments in that the intended for the overload case compliance to an elastic Spring preload of parts of the spindle 10 or the spindle nut 12 goes back, as will be shown. Alternatively, however, it may be provided that the flexibility provided for the overload case is plastic, so that at least a part of the screw engagement 14 does not recover after an overload. This can be realized, for example, by the overload-induced dissolution of the screw engagement 14 to a destruction of at least part of the spindle external thread 11 and / or the spindle nut internal thread 13 declining. The advantages of both variants have already been explained in the general part of the description.

Basically, the compliance provided for the overload case on a resilient design of the material of spindle 10 and / or spindle nut 12 decline. For this purpose, the spindle 10 or the spindle nut 12 be made of an at least partially elastic material. The life cycle challenges have been noted in the general part of the description.

For the realization of the intended for the overload case compliance are numerous advantageous variants conceivable. Here and preferably, for the generation of the intended for the overload case compliance, the spindle nut 12 at least two, here and preferably four, thread segments 17 on, referring to the spindle axis 7 extend over an angular range α and at least relative to the spindle axis 7 Radial direction are arranged yielding. Alternatively or additionally, the thread segments 17 be self-compliant. Preferably, the thread segments extend 17 each over an angular range between 30 ° and 180 °. At the in 2 illustrated and so far preferred embodiment extend the thread segments 17 each over an angular range of 25 °. The thread segments 17 are preferably designed as separate components.

Alternatively or in addition to the assignment of the thread segments 17 to the spindle nut 12 can the above-mentioned thread segments 17 the spindle 10 be assigned. This is in the illustration according to 4 merely hinted.

The thread segments 17 show at the in 2 illustrated embodiment, a segment internal thread 18 while in the embodiment according to 4 provided thread segments 17 one segment external thread each 19 exhibit.

Here and preferably it is the case that the thread segments 17 to one related to the spindle axis 7 complete circumferential screw thread. It may optionally be provided that individual angular ranges are omitted in the circumferential screw thread, in particular those angular ranges between two thread segments 17 are located.

In terms of a symmetrical arrangement, it is, as in 2 shown, preferably provided that the thread segments 17 relative to the spindle axis 7 each extend over an identical angle section α, here and preferably over an angular section of 90 °. Basically, it is also conceivable that the thread segments 17 extend over different angle sections, in particular to counteract by an irregular mass distribution of a possible tendency to vibrate.

The thread segments 17 are here and preferably designed as rigid components. The intended for the overload case compliance is achieved by the thread segments 17 by means of a spring arrangement 20 are mechanically biased. In a particularly preferred embodiment, it is such that the spring arrangement 20 at least one spring element 21 has, on at least one thread segment 17 acts. At the in 2 illustrated and so far preferred embodiment is each thread segment 17 at least one spring element 21 , here exactly one spring element 21 , assigned to the thread segment 17 acts. This allows a particularly uniform bias of the individual thread segments 17 achieve.

The spring arrangement 20 can affect the thread segments in different ways 17 Act. In the in the 2 and 3a , B embodiments shown, the spring arrangement acts 20 at least in relation to the spindle axis 7 radial direction on the thread segments 17 , This can be a possible deflection of the spring assembly 20 spring force can be dispensed with. This can be structurally particularly easy to implement when the spring assembly 20 at least in relation to the spindle axis 7 radially inward pointing direction to the thread segments 17 acts.

At the in 3c On the other hand, it is provided that the spring arrangement 20 at least in relation to the spindle axis 7 axial direction on the thread segments 17 acts. For this purpose, additional design measures are required, which will be explained below.

A synopsis of 1 . 2 and 3 shows that the spindle nut 12 via a spindle nut tube 22 with a drive connection 8th is coupled, with the spindle 10 in Dependence on the position of the spindle drive 1 within the spindle nut tube 22 extends. The spindle nut 12 is in the spindle nut tube 22 mounted against rotation (not shown). The 2 and 3 show that a particularly simple structural arrangement results when, as shown, the spring arrangement 20 for generating the mechanical prestressing of the thread segments 17 on the spindle nut tube 22 supported.

A particularly inexpensive and in the 2 and 3 arrangement shown in different variants results from the fact that the spring arrangement 20 at least one designed as a helical compression spring spring element 21 having. It is in the sense of a compact construction preferably so that the helical compression spring is a screw longitudinal axis 23 having, based on the spindle axis 7 radial ( 2 . 3a ) or axial ( 3c ) is aligned.

A particularly compact design results according to 3b in that the spring arrangement 20 at least two thread segments 17 at least over an angular section around the spindle axis 7 surrounds around. 3b shows a corresponding arrangement in which the spring arrangement 20 a part of the spindle nut 12 , here two thread segments 17 the spindle nut 12 , over an angular section, here and preferably over an angular section of 180 °, about the spindle axis 7 surrounds around. In this case, the spring arrangement 20 , as in 3b represented, be designed as a spring clip, resulting in a particularly cost manufacturability. Alternatively, the spring arrangement 20 be designed as a wrap, the corresponding thread segments 17 wraps. In both cases, it is provided that the spring clip 24 at least on the two mentioned thread segments 17 a mechanical bias in relation to the spindle axes 7 radial direction exerts. This can, as in 3b shown for the spindle nut 12 be valid. A corresponding application of a spring clip 24 or a wrap is on the in 4 shown spindle 10 conceivable.

For the design of the spring arrangement 20 Depending on the application, other advantageous variants are conceivable. For example, the spring arrangement 20 spring elements 21 each having a leaf spring, a spring tongue, a torsion spring o. The like. Are configured.

In the event that the spring elements 21 the spring arrangement 20 not in the radial direction on the thread segments 17 Act, constructive measures for the diversion of the spring force are required. At the in 3c illustrated embodiment is between the spring assembly 20 and the thread segments 17 a gear arrangement 25 connected. It is here and preferably so that the spring arrangement 20 in relation to the spindle axis 7 axial direction on the gear assembly 25 acts while the gear assembly 25 in each case at least in relation to the spindle axis 7 radial direction on the thread segments 17 acts. Here and preferably, the gear assembly 25 designed as a wedge gear. The spring elements designed as helical compression springs act here 21 axially on a first wedge 26 pointing to a wedge-shaped thread segment on the back 17 acts and a radial bias of the thread segment 17 causes. The high resulting gear ratio causes with a low spring force, a high mechanical bias of the thread segments 17 achieve. Particularly advantageous is the fact that a space that may be present in the axial direction can be utilized to a high mechanical bias of the thread segments 17 to achieve.

With the in 2 illustrated embodiment, it can be readily realized that the spindle 10 and the spindle nut 12 in the idle state, ie without axial load between the spindle 10 and spindle nut 12 , about the screw engagement 14 in exclusively positive engagement with each other. The arrangement is thus made such that the above, mechanical bias by the spring assembly 20 not to a frictional connection between the spindle 10 and the spindle nut 12 leads. In that regard, there is no unwanted braking rotation of the spindle 10 opposite the spindle nut 12 ,

Basically, the above, mechanical bias but just for the braking of a rotation of the spindle 10 opposite the spindle nut 12 be used. Accordingly, it is then preferably provided that the spindle 10 and the spindle nut 12 in the idle state, ie without axial load between the spindle 10 and spindle nut 12 , about the screw engagement 14 by the mechanical pretension of the thread segments 17 not only in positive engagement with each other, but also in frictional engagement with each other. It is provided in particular that the mechanical bias by the resulting frictional engagement braking a rotation of the spindle 10 opposite the spindle nut 12 caused. This can be in any case desired anyway, continuous braking of the drive train of the spindle drive 1 realize without additional effort.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 202008016929 U1 [0005]

Claims (15)

Spindle drive ( 1 ) for a closure element ( 2 ) of a motor vehicle, wherein a drive unit ( 3 ) and one of the drive unit ( 3 ) drive-downstream spindle spindle nut transmission ( 6 ) with geometric spindle axis ( 7 ) for generating linear drive movements between two drive connections ( 8th . 9 ), wherein the spindle spindle nut transmission ( 6 ) a spindle ( 10 ) with spindle external thread ( 11 ) and a spindle nut ( 12 ) with spindle nut internal thread ( 13 ) having a screw engagement ( 14 ), characterized in that the screw engagement ( 14 ) has a compliance such that in case of overload axial load between spindle ( 10 ) and spindle nut ( 12 ) above a predetermined overload limit the screw engagement ( 14 ) dissolves. Spindle drive according to claim 1, characterized in that the spindle ( 10 ) and / or the spindle nut ( 12 ) has or provide for the overload provided that the spindle external thread ( 11 ) and / or the spindle nut internal thread ( 13 ) is configured in such a way or that are in the case of overload the relative to the spindle axis ( 7 ) axial load between spindle ( 10 ) and spindle nut ( 12 ) by the intended for the overload compliance to a widening of the inner cross section of the spindle nut ( 12 ) and / or compressing the outer cross section of the spindle ( 10 ) leads. Spindle drive according to one of the preceding claims, characterized in that the resilience provided for the overload case is elastic, so that the screw engagement ( 14 ) is restored after an overload by elastic recovery, or that the intended for the overload case resilience is plastic, so at least a part of the screw engagement ( 14 ) does not recover after an overload Spindle drive according to one of the preceding claims, characterized in that the flexibility provided for the overload case on a resilient design of the material of spindle ( 10 ) and / or spindle nut ( 12 ) goes back. Spindle drive according to one of the preceding claims, characterized in that for the generation of the intended for the overload case compliance, the spindle ( 10 ) and / or the spindle nut ( 12 ) at least two thread segments ( 17 ), which in relation to the spindle axis ( 7 ) extend over an angular range (α) and which are configured and / or arranged to be yielding at least in the radial direction, preferably in that the thread segments ( 17 ) each extend over an angular range (a) between 30 ° and 180 °. Spindle drive according to claim 5, characterized in that the thread segments ( 17 ) relative to the spindle axis ( 7 ), omitting any angular areas, omit circumferential screw threads if necessary. Spindle drive according to claim 5 or 6, characterized in that the thread segments ( 17 ) relative to the spindle axis ( 7 ) each extend over an identical angle section (α). Spindle drive according to one of claims 5 to 7, characterized in that the thread segments ( 17 ) for generating the intended for the overload case compliance by means of a spring arrangement ( 20 ) are mechanically biased, preferably that the spring arrangement ( 20 ) at least one spring element ( 21 ), which on at least one thread segment ( 17 ), more preferably, that each thread segment ( 17 ) at least one spring element ( 21 ) associated with the thread segment ( 17 ) acts. Spindle drive according to claim 8, characterized in that the spring arrangement ( 20 ) at least in relation to the spindle axis ( 7 ) radial direction on the thread segments ( 17 ), preferably, that the spring arrangement ( 20 ) at least in relation to the spindle axis ( 7 ) radially inwardly facing direction on the thread segments ( 17 ) acts. Spindle drive according to claim 9, characterized in that the spindle nut ( 12 ) via a spindle nut tube ( 22 ) with a drive connection ( 8th ), wherein the spindle ( 10 ) within the spindle nut tube ( 22 ), preferably that the spring arrangement ( 20 ) for generating the mechanical prestress of the thread segments ( 17 ) on the spindle nut tube ( 22 ) is supported. Spindle drive according to claim 9 or 10, characterized in that the spring arrangement ( 20 ) has at least one helical compression spring, preferably that the helical compression spring is a helical longitudinal axis ( 23 ), which relative to the spindle axis ( 7 ) is aligned radially or axially. Spindle drive according to one of claims 9 to 11, characterized in that the spring arrangement ( 20 ) at least a part of the spindle nut ( 12 ), in particular at least two thread segments ( 17 ), at least over an angular section around the spindle axis ( 7 ) around. Spindle drive according to claim 12, characterized in that the spring arrangement ( 20 ) as a spring clip ( 24 ) or designed as a wrap spring, the at least two thread segments ( 17 ) a mechanical bias in relation to the spindle axis ( 7 ) exerts radial direction. Spindle drive according to one of claims 9 to 13, characterized in that between the spring arrangement ( 20 ) and the thread segments ( 17 ) a gear arrangement ( 25 ), preferably that the spring arrangement ( 20 ) in relation to the spindle axis ( 7 ) axial direction on the gear arrangement ( 25 ) and that the gear arrangement ( 25 ) at least in relation to the spindle axis ( 7 ) radial direction on the thread segments ( 17 ), more preferably, that the gear arrangement ( 25 ) is designed as a wedge gear. Spindle drive according to one of the preceding claims, characterized in that the spindle ( 10 ) and the spindle nut ( 12 ) in the idle state without axial load between spindle ( 10 ) and spindle nut ( 12 ) via the screw engagement ( 14 ) in exclusively positive engagement with each other, or that the spindle ( 10 ) and the spindle nut ( 12 ) in the idle state without axial load between spindle ( 10 ) and spindle nut ( 12 ) via the screw engagement ( 14 ) by the mechanical bias of the thread segments ( 17 ) are also in frictional engagement with each other, preferably, that the mechanical bias braking a rotation of the spindle ( 10 ) opposite the spindle nut ( 12 ) caused.

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