Patent ID: 12203314

DETAILED DESCRIPTION

Embodiments of the present disclosure are described herein. It is to be understood, however, that the disclosed embodiments are merely examples and other embodiments can take various and alternative forms. The figures are not necessarily to scale; some features could be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the embodiments. As those of ordinary skill in the art will understand, various features illustrated and described with reference to any one of the figures can be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. Various combinations and modifications of the features consistent with the teachings of this disclosure, however, could be desired for particular applications or implementations.

A known spindle drive is disclosed in DE 20 2017 102 066 U1, is equipped with a rotary drive motor, a speed reduction gear connected downstream of the drive motor, and a feed mechanism connected downstream of the speed reduction gear. The speed reduction gear of the known spindle drive is designed as a planetary gear assembly with a planetary gear which, as the usual planetary gear components, has a sun wheel, an annulus and a planet carrier with planets. In order to produce linear drive movements in an axial direction, the feed mechanism is designed as a spindle-spindle nut mechanism which has a spindle on the drive side and a spindle nut on the output side as the usual mechanism components.

The known spindle drive may be advantageous since it permits reliable holding of the adjustable element in the open position or in intermediate positions. For this purpose, a braking arrangement which brakes the rotational movement of the drive spindle is provided in the drive train of the spindle drive. In this case, the braking arrangement is designed as a separate unit which has frictional engagement elements that are in frictional engagement with one another and provide the braking action by means of the frictional engagement produced. In this case, the unit comprising the braking arrangement is connected in terms of drive between the planetary gear of the planetary gear assembly and the spindle-spindle nut mechanism. In this case, the planetary gear has an output element on the output side, which interacts with a drive element of the braking arrangement in terms of drive, that is to say in a torque-transmitting manner. In turn, the braking arrangement itself has an output-side output element, which interacts with a drive element of the spindle-spindle nut mechanism, in this case the spindle. All the aforementioned drive components of the spindle drive, namely the drive, speed reduction gear, braking arrangement and feed mechanism, are accommodated one behind the other in an elongate, telescopic drive housing and are aligned with a common drive axis, the direction of extent of which is referred to below as the axial direction. The drive housing has a correspondingly large technical length and accordingly takes up a relatively large amount of installation space in the motor vehicle.

The problem underlying the invention is that of configuring and developing the known spindle drive in such a way that its technical length and thus the installation space required in the motor vehicle are reduced.

The spindle drive illustrated in the drawing serves for the motor-driven adjustment of an adjustable element1of a motor vehicle designed as a tailgate. This is to be understood to be advantageous, but not restrictive. On the contrary, the spindle drive according to the proposal can be used for all possible adjustable elements of a motor vehicle, as will be explained further below.

The spindle drive is equipped with a drive motor2, a speed reduction gear3connected downstream of the drive motor2, and a feed mechanism4, connected downstream of the speed reduction gear, for generating linear drive movements. The speed reduction gear3is designed as a planetary gear assembly with at least one planetary gear3a,3b. According toFIG.3a), the planetary gear assembly has a single planetary gear3a, whereas the planetary gear assembly according toFIG.3b) has two planetary gears3a,3bconnected in series in terms of drive. In order to produce the linear drive movements, the feed mechanism4connected downstream of the planetary gear assembly in terms of drive, is configured as a spindle-spindle nut mechanism.

The respective planetary gear3a,3bmay include a sun wheel5, a planet carrier6with planets6a, and an annulus7as planetary gear components. The sun wheel5is rotatable about a corresponding sun wheel axis. Coaxially therewith, the planet carrier6is rotatable about a planet carrier axis, wherein the planets6aare each rotatable on the planet carrier6about their own planet axes. The annulus7is also rotatable coaxially with the sun wheel5on an annulus axis, wherein the annulus7may be fixed with respect to the housing, that is to say permanently fixed rotationally and axially. It is also conceivable that the annulus7is lockable, enabling it to be locked or to be freely rotatable about its annulus axis, depending on the state. In the latter case, the respective planetary gear3a,3bcan be used as a shiftable clutch. The planets6aare in axially parallel engagement with the sun wheel5, on the one hand, and with the annulus7, on the other hand. Here, the term “axially parallel” means that the sun wheel axis, the planet axes and the annulus axis are aligned parallel to one another.

The feed mechanism4, which is designed as a spindle-spindle nut mechanism, has a drive-side mechanism component and an output-side mechanism component in meshing engagement therewith (FIG.2). “Drive side” means the side in the drive train of the spindle drive on which the torque is generated, i.e. the motor side. The drive-side mechanism component is thus the mechanism component which receives the rotary motion generated by the drive motor2and transmitted by the speed reduction gear3and transmits it to the output-side mechanism component. As an example, the drive-side mechanism component is a spindle8and the output-side mechanism component is a spindle nut9in meshing engagement therewith. Alternatively, it is also possible to conceive of an embodiment in which the drive motor2drives the spindle nut9instead of the spindle8via the speed reduction gear3, the spindle nut9then forming the drive-side mechanism component and the spindle8forming the output-side mechanism component.

As an example, the torque generated by the drive motor2is permanently transmitted to the spindle8via the planet carrier6coupled to the feed mechanism4. “Coupled” means that the two respective elements, in this case planet carrier6and spindle8, are in engagement with one another in terms of drive, that is to say in a torque-transmitting manner. Alternatively, it is also possible to conceive of an embodiment in which the torque generated by the drive motor2is transmitted to the spindle8either via the annulus7or via the planet carrier6, depending on the gear position of the respective planetary gear3a,3b.

Furthermore, a braking arrangement10is provided which brakes the rotary motion of the spindle8and permits reliable holding of the adjustable element1, for example a tailgate, in intermediate positions.

A particularly slim design may result from the fact that the drive motor2, the speed reduction gear3and the feed mechanism4are accommodated one behind the other in a substantially elongate drive housing11and are aligned with a common drive axis12.

As an example, it is possible with the respective planetary gear3a,3bto form a non-self-locking configuration of the speed reduction gear3. For this purpose, the respective planetary gear3a,3bcan be configured as a gear with helical teeth, for example. The planetary gear3a,3bcan, for example, also be configured as an evoloid gear, the sun wheel5of which has only a single pinion tooth, which has an involute profile running in a spiral around the sun wheel axis. The planets6aand the annulus7then have corresponding teeth. Reference may be made to DE 20 2011 106 149 U1 for the technical details of such evoloid toothing. It may be provided that the speed reduction gear3, or even the entire drive train that may include the drive motor2, speed reduction gear3and feed mechanism4, is of a non-self-locking configuration. This is may be advantageous when the spindle drive is used as a tailgate drive, making manual adjustment of the tailgate1readily possible when the drive motor2is not being supplied with power.

In the spindle drive according to the proposal, as already indicated above, a torque is now transmitted from the single planetary gear3a(FIG.3a)) or the planetary gear3b(FIG.3b)) which, in terms of drive, is at the rear of the planetary gear assembly to the downstream feed mechanism4, more specifically inasmuch as the planet carrier6of the planetary gear3aor planetary gear3bcoupled to the feed mechanism4is connected to an output element13for conjoint rotation therewith. Here and for preference, the output element13is configured as an output claw and transmits the torque, such as, to a spindle connection, which can be configured as a corresponding drive claw and which is connected to the spindle8for conjoint rotation therewith. On the drive side, the planetary gear assembly has a drive element14, which is provided for transmitting a drive-side torque, that is to say a torque of the drive motor2, to the planet carrier6of the respective drive-side planetary gear3a, and which is connected to the sun wheel5for conjoint rotation therewith. As an example, the drive element14may also configured as an output claw and transmits the torque, for example, to a connection of the motor shaft of the drive motor2, which may be configured as a corresponding output claw.

The crucial point is now that the braking arrangement10has at least one first frictional engagement element15a,15b, which is fixed in terms of rotation relative to the drive housing11, and at least one second frictional engagement element16a,16b, which is in frictional engagement with the respective first frictional engagement element15a,15band is connected to the planet carrier or one of the planet carriers6for conjoint rotation therewith. As an example, the braking arrangement10is designed for continuous braking of the respective planet carrier6. An additional braking arrangement10to the one described here and may not be provided in the drive train of the spindle drive. The braking arrangement10is thus preferably the only braking arrangement of the spindle drive.

FIGS.3a) and3b) show two different exemplary embodiments of a spindle drive according to the proposal having such a braking arrangement10. In this case, the planetary gear assembly according toFIG.3a) has only a single planetary gear3a, whereas the planetary gear assembly according to the exemplary embodiment inFIG.3b) has two planetary gears3a,3bconnected in series.

In the following, the exemplary embodiment according toFIG.3a) will first be explained in more detail.

As an example, the planet carrier6, which here is the only planet carrier6of the planetary gear assembly, is provided on its two axial sides with a respective second frictional engagement element16a,16b, namely on the axial side facing the feed mechanism4with frictional engagement element16aand on the axial side facing the drive motor2with frictional engagement element16b. Each of the second frictional engagement elements16a,16binteracts frictionally with an associated first frictional engagement element15a,15b, each of which is fixed in terms of rotation relative to the drive housing11. Here, frictional engagement element16aof the planet carrier6interacts, in each case frictionally, with a frictional engagement element15aon the housing side, and the other frictional engagement element16bof the planet carrier6interacts with the other frictional engagement element15bon the housing side. In one or more embodiments, the respective frictional resistance between frictional engagement elements15aand16a, on the one hand, and between frictional engagement elements15band16b, on the other hand, is equal. In principle, however, it is also conceivable to provide frictional resistances of different magnitudes between the individual pairs of frictional engagement elements. Thus, it is conceivable to provide balls, rollers or the like in the case of one pair of frictional engagement elements, for example between frictional engagement elements15band16b, thus ensuring that only rolling friction occurs here, whereas in the case of the other pair of frictional engagement elements static friction occurs when the spindle drive is stationary and sliding friction occurs during operation of the spindle drive. The rolling friction then causes, in particular, lower frictional resistance than the static or sliding friction.

In one or more embodiments, exactly one frictional engagement element16a,16bis provided on the planet carrier6on each axial side. In principle, however, it is also possible to provide more than one frictional engagement element16a,16bon one or the other axial side or on both axial sides of the planet carrier6. The same applies to the frictional engagement elements15a,15bon the housing side, of which, here too, in each case only one is provided on the relevant axial side. In principle, however, it is also possible to provide more than one housing-side frictional engagement element15a,15bon one or the other axial side or on both axial sides of the planet carrier6.

In principle, as illustrated inFIG.3a) andFIG.3b), it is conceivable for the respective first frictional engagement element15a,15bor at least one of the first frictional engagement elements15a,15band the second frictional engagement element16a,16bor at least one of the second frictional engagement elements16a,16bto be in frictional engagement with one another in the axial direction X. In the exemplary embodiment inFIG.3a), it is accordingly the case that the one first frictional engagement element15ais in frictional engagement with the one second frictional engagement element16aand the other first frictional engagement element15bis in frictional engagement with the other second frictional engagement element16bin each case in the axial direction X. As an example, therefore, the planet carrier6transmitting the torque to the drive-side mechanism component, here the spindle8, is braked axially.

Alternatively, though not illustrated here, provision can also be made, however, for the first frictional engagement element15a,15bor at least one of the first frictional engagement elements15a,15band the second frictional engagement element16a,16bor at least one of the second frictional engagement elements16a,16bto be in frictional engagement with one another radially. Thus, it is also conceivable here for the one first frictional engagement element15aand the one second frictional engagement element16aand/or the other first frictional engagement element15band the other second frictional engagement element16beach to be in frictional engagement with one another radially. Frictional engagement elements15a,16a, on the one hand, and frictional engagement elements15b,16b, on the other hand, can be in frictional engagement with one another radially on the inside and/or radially on the outside of the planet carrier6.

FIG.3b) illustrates an exemplary embodiment with two planetary gears3a,3b. The two planetary gears3a,3bare connected in series in terms of drive and in this case are, in particular, fixedly coupled to one another. “Fixed coupling” means that the drive connection cannot be released by means of a clutch. In principle, however, the two planetary gears3a,3bcan also be coupled to one another via a clutch.

In this case, one planetary gear3ais coupled to the drive side of the spindle drive, namely to the drive motor2, whereas the other planetary gear3bis coupled to the spindle-spindle nut mechanism. As an example, the planetary gear3acoupled to the drive side is connected upstream of the planetary gear3bcoupled to the spindle-spindle nut mechanism. Correspondingly, the planet carrier6transmitting the torque to the drive-side mechanism component, here the spindle8, is the planet carrier6of the planetary gear3bat the rear in terms of drive. In this case, the sun wheel5of this planetary gear3bat the rear in terms of drive is coupled to the planet carrier6of the planetary gear3awhich is connected upstream or at the front in terms of drive. In this case, the sun wheel5of planetary gear3band the planet carrier6of planetary gear3aare arranged on a common shaft for conjoint rotation therewith.

It should be noted that, in the exemplary embodiment according toFIG.3b), exactly two planetary gears3a,3bare provided, which are connected in series. In principle, however, in an alternative embodiment not illustrated here, it is also possible to provide more than two planetary gears, which are connected in series. In this case, too, the planetary gear at the rear in terms of drive would be the planetary gear coupled to the spindle-spindle nut mechanism. At least two further planetary gears would then be connected in series upstream of the latter in terms of drive, and it would be possible for one of the planetary gears connected upstream in terms of drive to be coupled in the manner described to the planetary gear which is at the rear in terms of drive. At least one further planetary gear would in turn be connected upstream of the planetary gear which would be connected directly upstream of the planetary gear which is at the rear in terms of drive, which further gear would, in particular, be connected to the drive motor2.

In the case described, in which the planetary gear assembly has a plurality of, in particular two, planetary gears3a,3b, the braking arrangement10preferably has at least one third frictional engagement element19a,19b, which is connected for conjoint rotation to the planet carrier6of that planetary gear3awhich, in terms of drive, is connected upstream of the planetary gear3bcoupled to the spindle-spindle nut mechanism. In this case, the at least one third frictional engagement element19a,19bis in each case in frictional engagement with at least one of the further frictional engagement elements15a,15b,16a,16b.

In the exemplary embodiment inFIG.3b), the braking arrangement10has a third frictional engagement element19a,19bon each axial side of the planet carrier6of the planetary gear3awhich is at the front in terms of drive, the third frictional engagement element being connected to the planet carrier6for conjoint rotation therewith. In this case, on the axial side of the planet carrier6of the planetary gear3aat the front in terms of drive, the side facing the feed mechanism4, a third frictional engagement element19aof the planet carrier6interacts frictionally with a second frictional engagement element16bof the planet carrier6of the planetary gear3bat the rear in terms of drive. On the axial side of the planet carrier6of the planetary gear3awhich faces the drive motor2, a further third frictional engagement element19bof the planet carrier6interacts frictionally with a first frictional engagement element15bsituated on the housing side. In the case of the planetary gear3bwhich is at the rear in terms of drive, a further second frictional engagement element16aof the planet carrier6of planetary gear3binteracts frictionally, on the axial side facing the feed mechanism4, with a further first frictional engagement element15asituated on the housing side.

In a case with a planetary gear assembly which has a plurality of, in particular two, planetary gears3a,3b, as is illustrated by way of example inFIG.3b), it is preferably the case that the frictional engagement elements interacting with one another frictionally in each case, or at least individual ones of the frictional engagement elements interacting with one another frictionally in each case, are in frictional engagement with one another in the axial direction. In one exemplary embodiment (shown inFIG.3b), frictional engagement elements15aand16a, frictional engagement elements16band19aas well as frictional engagement elements19band15beach interact with one another frictionally in the axial direction. Accordingly, it can be provided that the third frictional engagement element19aor at least one of the third frictional engagement elements19a,19band at least one of the second frictional engagement elements16a,16bare in frictional engagement with one another in the axial direction X. Additionally or alternatively, it can be provided that the third frictional engagement element19bor at least one of the third frictional engagement elements19a,19band at least one of the first frictional engagement elements15a,15bare in frictional engagement with one another in the axial direction X.

Additionally or alternatively, the first frictional engagement element15a,15bor the second frictional engagement element16a,16b, each of which interacts frictionally with a third frictional engagement element19a,19b, may also be in frictional engagement radially with the third frictional engagement element19a,19b. Accordingly, it can be provided that the third frictional engagement element19aor at least one of the third frictional engagement elements19a,19band at least one of the second frictional engagement elements16a,16bare in frictional engagement with one another radially. Additionally or alternatively, it can also be provided that the third frictional engagement element19bor at least one of the third frictional engagement elements19a,19band at least one of the first frictional engagement elements15a,15bare in frictional engagement with one another radially.

As an example, the braking arrangement10has a contact pressure mechanism17for generating a contact pressure force, here an axial contact pressure force, of the frictional engagement elements toward one another. In the case of radial frictional engagement, as described above, between in each case two frictional engagement elements, it is also possible to provide a contact pressure mechanism which generates a corresponding radial contact pressure force of the frictional engagement elements toward one another. The contact pressure force of the frictional engagement elements is preferably adjustable.

In one or more embodiments, the contact pressure mechanism17may include a spring arrangement18, the spring preload of which defines the contact pressure force. The spring preload and thus the contact pressure force may be adjustable. As an example, the spring arrangement18may include at least one helical spring, in particular a helical compression spring.

Achieving adjustability of the contact pressure force by means of a spring arrangement18, the spring preload of which is adjustable, is not the only conceivable possibility. Additionally or alternatively, it is also conceivable for the contact pressure force to be adjustable via the adjustment of gear components with helical teeth or evoloid teeth in the respective planetary gear3a,3b.

As an example, it is further provided that the output element13, which is connected for conjoint rotation to the planet carrier6which transmits the torque to the drive-side mechanism component, in particular the spindle8, is arranged radially inside an axial section10aof the braking arrangement10and/or radially inside an axial section17aof the contact pressure mechanism17. Additionally or alternatively, the drive element14, which is provided for transmitting a drive-side torque to the planet carrier6of the respective drive-side planetary gear3a,3band is connected to the sun wheel5for conjoint rotation therewith, can also be arranged radially inside an or the axial section10aof the braking arrangement10and/or radially inside an or the axial section17aof the contact pressure mechanism17. In each case, this has the advantage that the technical length of the spindle drive can be further reduced.

Finally, the mode of operation of the feed mechanism4may be discussed in more detail. Operation of the drive motor2causes a speed-reduced rotation of the output element13of the speed reduction gear3, which is transmitted to the spindle8. Rotation of the spindle8causes a linear adjustment of the spindle nut9and thus a linear adjustment of a guide tube20, which is fixedly connected to the spindle nut9. The guide tube20is in turn connected in the region of a connection21of the spindle drive to a housing outer tube11aof the drive housing11, which can be telescoped with respect to a housing inner tube11bof the drive housing11. The housing inner tube11bis, in turn, connected to an opposing connection22. It furthermore accommodates the preferably preassembled unit comprising the drive motor2, speed reduction gear3and braking arrangement10. If appropriate, a clutch, not illustrated here, can also be provided in the drive train, and can likewise be a component of the preassembled unit. As an example, the spindle drive can be assembled as a variable modular system, depending on customer requirements.

According to another embodiment, an adjustable element assembly of a motor vehicle having an adjustable element1and a spindle drive above according to the proposal for motor-driven adjustment of the adjustable element1is provided. Reference may be made to all statements regarding the spindle drive according to the proposal which are suitable for explaining the adjustable element assembly.

As explained above, numerous variants are conceivable for the adjustable element1. In a particularly preferred configuration, the adjustable element1is a tailgate, a trunk lid, a door, in particular a side door, an engine hood or the like, of a motor vehicle.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications.

The following is a list of reference numbers shown in the Figures. However, it should be understood that the use of these terms is for illustrative purposes only with respect to one embodiment. And, use of reference numbers correlating a certain term that is both illustrated in the Figures and present in the claims is not intended to limit the claims to only cover the illustrated embodiment.

LIST OF REFERENCE NUMBERS

1adjustable element2drive motor3speed reduction gear4downstream feed mechanism5sun wheel6planet carrier7annulus8spindle9spindle nut10braking arrangement11drive housing12common drive axis13output element14drive element17contact pressure mechanism18spring arrangement20guide tube21connection22connection3aplanetary gear3bplanetary gears6aplanets10aaxial section11ahousing outer tube11bhousing inner tube15afirst frictional engagement elements15bfrictional engagement element16asecond frictional engagement element16bsecond frictional engagement element17aaxial section19athird frictional engagement elements19bthird frictional engagement elements