Spindle drive

Abstract

Spindle drive (1) for a flap (2) of a motor vehicle with a motor drive assembly (6), with a spindle drive (7) connected downstream of the motor drive assembly (6) and with two drive connections (8, 9) for transmitting drive movements, wherein the spindle drive (7) has a spindle (10) rotatable from the motor drive assembly (6) and a non-rotatable spindle nut (11) engaging therewith, wherein the spindle nut (11) performs an axial retraction movement (12), during which the distance between the two drive connections (8, 9) decreases, and an axial extension movement (13), during which the distance between the two drive connections (8, 9) increases, depending on the direction of rotation of the spindle (10), wherein the spindle nut thread (11a) extends beyond the spindle thread (10a) at least in the fully retracted position in the direction of the retraction movement (12) and engages at least a part of the motor drive assembly (6). encompasses,characterized in that a spring arrangement (21) is provided which biases the two drive connections (8, 9) against each other.

Description

[0001] The present invention relates to a spindle drive for a flap of a motor vehicle according to the preamble of claim 1 and to a flap arrangement of a motor vehicle according to claim 13.

[0002] The term "hatch" is to be understood broadly in this context. It includes, for example, a tailgate, a trunk lid, a hood, a side door, a cargo area flap, a lifting roof, or similar parts of a motor vehicle. The following focuses on the application of the motorized adjustment of a tailgate of a motor vehicle. This is not to be understood as a limitation.

[0003] The use of spindle drives for motorized tailgate adjustment of a vehicle has become increasingly important in recent years. In addition to high operational reliability, maximum compactness is a frequently requested requirement.

[0004] The known spindle drive (DE 10 2008 062 391 A1), from which the invention is based, is equipped with a motor drive assembly and a spindle gear arranged downstream of the motor drive assembly. A spindle extending over a substantial axial section of the spindle drive meshes with a spindle nut, which accordingly runs on the spindle. The spindle gear and the motor drive assembly are arranged one behind the other along the geometric spindle axis. Thus, the length of the spindle drive is also determined by the length of the motor drive assembly, which fundamentally limits the achievable compactness.

[0005] Further prior art relating to such a spindle drive is also known from the documents US 3 751 998 A, DE 692 22 756 T2, WO 2009 / 038 212 A1 and US 2009 / 0 200 830 A1.

[0006] The invention is based on the problem of designing and developing the known spindle drive in such a way that its compactness is increased by simple means.

[0007] 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.

[0008] It is important to consider that, with appropriate design, the motor drive arrangement can be nested with the spindle gear, which allows the length of the spindle drive to be reduced for a given stroke.

[0009] Specifically, it is proposed that the spindle nut thread extends beyond the spindle thread, at least in the fully retracted position, in the direction of its retraction movement and encloses at least part of the motor drive assembly. In the fully retracted position, the motor drive assembly and the spindle nut thread overlap at least partially. This ensures that the motor drive assembly contributes little or nothing to the length of the spindle drive in the fully retracted position.

[0010] The preferred embodiments according to claims 7 to 9 relate to a particularly compact design in which the inner diameter of the spindle nut is matched to the corresponding dimension of the part of the motor drive assembly enclosed by the spindle nut. With a tubular drive housing according to claim 8, the compactness can be further increased in the radial direction relative to the geometric spindle axis.

[0011] The further preferred embodiment according to claim 11 provides for a compact implementation of the preload of the two drive connections against each other. The outer side of the spindle nut serves as a guide for a helical spring arrangement, which is preferably a helical compression spring arrangement.

[0012] According to a further teaching according to claim 13, which has independent significance, a flap assembly of a motor vehicle is claimed, comprising a flap for closing a flap opening and at least one proposed spindle drive associated with the flap. Reference is made to all statements regarding the proposed spindle drive that are suitable for describing the flap assembly.

[0013] The invention will be explained in more detail below with reference to a drawing which merely represents an exemplary embodiment. Fig. 1 in a schematic side view the rear of a motor vehicle with a proposed spindle drive and Fig. 2 a spindle drive according to Fig. 1 in the fully retracted position in a longitudinal section and Fig. 3 a spindle drive according to Fig. 1 in the fully extended position in longitudinal section.

[0014] The spindle drive 1 shown in the drawing is used for the motorized adjustment of a flap 2 of a motor vehicle, which is designed here as a tailgate. Reference should be made to the broad interpretation of the term "flap" mentioned above.

[0015] The flap 2 serves in the usual way to close a flap opening 3. The spindle drive 1 is arranged laterally of the flap opening 3, here and preferably in a gutter 4 located laterally of the flap opening 3. Fig. 1 shows only a single spindle drive 1. Here, however, and preferably, it is provided that a spindle drive 1 is arranged on each side of the flap opening 3. The two spindle drives 1 are structurally essentially identical.

[0016] According to the illustration, Fig. 1 that the spindle drive 1 shown there is hinged at one end to the body 5 of the motor vehicle and at the other end to the flap 2. The spindle drive 1 advantageously has a short length, which results from the proposed design of the spindle drive 1.

[0017] The spindle drive 1 has a motor drive assembly 6, which is connected downstream of a spindle gear 7. Furthermore, the spindle drive 1 is equipped with two drive connections 8, 9, which serve to transmit drive movements.

[0018] The spindle gear 7 is designed as a spindle-spindle nut gear and has a spindle 10 rotatable by the motor drive assembly 6 and a spindle nut 11 engaging with the spindle 10 and generally rotationally fixed relative to the spindle drive 1. Depending on the direction of rotation of the spindle 10, the spindle nut 11 performs an axial retraction movement 12, during which the distance between the two drive connections 8, 9 decreases, and an axial extension movement 13, during which the distance between the two drive connections 8, 9 increases.

[0019] The spindle 10 is equipped, as is conventional, with a spindle thread 10a, and the spindle nut 11 is also conventionally equipped with a spindle nut thread 11a. Depending on the design constraints, the spindle nut thread 11a may extend over only an axial portion of the spindle nut 11.

[0020] The terms “axial” and “radial” always refer to the geometric spindle axis 14.

[0021] It is now essential that the spindle nut thread 11a is at least in the Fig. 2, extends beyond the spindle thread 10a in the direction of the retraction movement 12 and encloses at least part of the motor drive arrangement 6. Fig. 2 shows that this achieves a nesting of the drive arrangement 6 with the spindle nut 11, which is accompanied by a particularly short design of the spindle drive 1.

[0022] Fig.Figure 2 further shows that the spindle nut thread 11a, in the fully retracted position, encloses the motor-drive assembly 6 over its entire axial extent. This achieves maximum component density along the geometric spindle axis 14. In any case, it is advantageous if the spindle nut thread 11a, in the fully retracted position, encloses the motor-drive assembly 6 over more than half its axial extent.

[0023] What is interesting about the illustrated embodiment is the fact that the portion of the spindle nut thread 11a that "exceeds" the spindle thread 10a accounts for more than 70% of the axial extent of the spindle nut thread 11a. In the illustrated embodiment, this means that the entire threaded section of the spindle nut thread 11a required for the extension movement 13 is provided by the excess portion. Thus, in the illustrated embodiment, the possibilities for reducing the length of the spindle drive 1 have been fully exploited.

[0024] A particularly advantageous feature of the spindle drive 1 shown is the fact that its components are arranged essentially coaxially. For example, the motor drive assembly 6 comprises a drive motor 15 with a drive shaft (not shown) that is aligned coaxially with the geometric spindle axis 14. Furthermore, the motor drive assembly 6 comprises an intermediate gear 16 connected downstream of the drive motor 15, which, in a particularly preferred embodiment, is aligned coaxially with the geometric spindle axis 14. The intermediate gear 16 is preferably designed as a torque transmission gear.

[0025] A coaxial alignment of the intermediate gear 16 with the geometric spindle axis 14 can be easily achieved by designing the intermediate gear 16 as a planetary gear. The coaxial alignment of the planetary gear 16 with the geometric spindle axis 14 preferably means that the sun gear, the planetary gear carrier, and the ring gear of the planetary gear 16 are correspondingly aligned coaxially with the geometric spindle axis 14.

[0026] In order to achieve a high packing density, the spindle 10 and the motor drive arrangement 6 are preferably arranged directly one behind the other along the geometric spindle axis 14.

[0027] The structural design of the spindle drive 1 shown in the drawing ensures high robustness not only with regard to the transmission of drive forces, but also with regard to potentially adverse environmental conditions such as moisture, dust, etc. First of all, it is provided that the spindle nut 11 is tubular in design with an inner diameter that is at least slightly larger than the corresponding dimension of the part of the motor drive assembly 6 enclosed by the spindle nut 11. The spindle 10 has a correspondingly large outer diameter to ensure engagement with the spindle nut 11.

[0028] What is interesting about the embodiment shown in the drawing is the fact that the motor drive assembly 6 has a tubular drive housing 17, over which the spindle nut 11 slides with play during the retraction movement. To bridge the play between the spindle nut 11 and the drive housing 17, a sliding assembly 18, here preferably annular, is provided, which slides on the drive housing 17. The sliding assembly 18 can have a sealing function and / or a bearing function. The sliding assembly 18 is located at an axial end of the spindle nut 11. The sliding assembly 18 is preferably an add-on part that is glued, clipped, or similarly attached to the spindle nut 11.

[0029] Of particular importance for the functionality of the spindle drive 1 is that the spindle nut 11 engages the motor drive assembly 6, here and preferably the drive housing 17 of the motor drive assembly 6, in a rotationally secure manner. The sliding assembly 18 can be used to implement the rotational lock by providing some form of positive engagement between the sliding assembly 18 and the drive housing 17. In the simplest case, the drive housing 17 is equipped with a groove aligned parallel to the geometric spindle axis 14, into which a web provided on the sliding assembly 18 engages. Other variants for the rotational lock are conceivable.

[0030] It is understood that the tubular spindle nut 11 has a substantially circular cross-section. Accordingly, the tubular drive housing 17 is preferably substantially circular, at least in sections. In a particularly preferred embodiment, the tubular spindle nut and / or the tubular drive housing 17 are sheet metal parts, preferably produced by a deep-drawing process, with the spindle nut thread being molded, for example, using a plastic injection molding process.

[0031] The two drive connections 8, 9 are each equipped with a ball socket 8a, 9a, which can be engaged with corresponding ball heads during assembly of the spindle drive 1. The drive connections 8, 9 are each connected to a cap 19, 20. One drive connection 8 is connected to one end of the spindle nut 11 via the cap 19. This connection can be made, for example, by crimping or the like. The other drive connection 9 is connected to the motor drive assembly 6, here to the drive housing 17 of the motor drive assembly 6, via the cap 20. A crimp connection is also suitable here.

[0032] In order to assist the motor drive arrangement 6 in adjusting the flap 2, a spring arrangement 21 is proposed which prestresses the two drive connections 8, 9 against one another. Depending on the application, it may be advantageous for the two drive connections 8, 9 to be prestressed towards one another or apart. In the illustrated and thus preferred embodiment, the spring arrangement 21 is designed as a helical spring arrangement, here and preferably as a helical compression spring arrangement, which presses the two drive connections 8, 9 apart. All statements regarding a helical compression spring arrangement apply accordingly to a helical tension spring arrangement. The helical spring arrangement 21 is aligned concentrically to the geometric spindle axis 14 and encloses the spindle nut 11. Here and preferably, the helical spring arrangement 21 encloses the spindle nut 11 with a certain amount of play.

[0033] In the illustrated embodiment, the helical compression spring arrangement 21 comprises only a single helical compression spring. However, it is conceivable that the helical compression spring arrangement 21 comprises several helical compression springs, which ultimately produce a very specific spring characteristic tailored to the kinematics of the flap 2. In the alternative embodiment with a helical tension spring arrangement, at least one helical tension spring is provided, whereby the spring can be screwed onto the caps 19, 20 or the like on both sides via approximately three spring coils.

[0034] Another interesting feature of the illustrated embodiment is the fact that the helical compression spring of the helical compression spring assembly 21 has a spring wire with a polygonal cross-section, here preferably a rectangular or even square cross-section. Such a configuration allows for further reduction of compactness in the radial direction relative to the geometric spindle axis 14.

[0035] According to a further teaching, which also has independent significance, a flap assembly of a motor vehicle is claimed, comprising a flap 2 for closing a flap opening 3 and at least one spindle drive 1, as described above, associated with the flap 2. Reference is made to all statements regarding the proposed spindle drive 1.

[0036] In a particularly preferred embodiment, the at least one spindle drive 1 is arranged laterally of the flap opening 3, here and preferably in a gutter 4. Reference may also be made to the above explanations with regard to this particularly preferred embodiment.

Claims

[1] Spindle drive (1) for a flap (2) of a motor vehicle, comprising a motor drive arrangement (6), a spindle gear (7) arranged downstream of the motor drive arrangement (6) in terms of drive technology, and two drive connections (8, 9) for transmitting drive movements, wherein the spindle gear (7) has a spindle (10) which is rotatable by the motor drive arrangement (6) and a rotationally fixed spindle nut (11) which is engaged therewith, wherein the spindle nut (11), depending on the direction of rotation of the spindle (10), performs an axial retraction movement (12), in which the distance between the two drive connections (8, 9) decreases, and an axial extension movement (13), in which the distance between the two drive connections (8, 9) increases, wherein the spindle nut thread (11a), at least in the fully retracted position, extends beyond the spindle thread (10a) in the direction of the retraction movement (12) and covers at least part of the Motor drive arrangement (6) encloses,characterized by that a spring arrangement (21) is provided which prestresses the two drive connections (8, 9) against each other. [2] Spindle drive (1) according to claim 1, characterized by that the spindle nut thread (11a) in the fully retracted position encloses the motor drive arrangement (6) over more than half its axial extent, preferably over its entire axial extent. [3] Spindle drive (1) according to claim 1 or 2, characterized by that the spindle nut thread (11a) in the fully retracted position extends beyond the spindle thread (10a) by more than 70% of its axial extent in the direction of the retraction movement (12). [4] Spindle drive (1) according to one of the preceding claims, characterized by that the motor drive arrangement (6) has a drive motor (15) with a drive shaft which is aligned coaxially with the geometric spindle axis (14). [5] Spindle drive (1) according to one of the preceding claims, characterized by that the motor drive arrangement (6) has an intermediate gear (16) connected downstream of the drive motor (15), preferably that the intermediate gear (16) is designed as a torque transmission gear, further preferably that the intermediate gear (16) is designed as a planetary gear, further preferably that the planetary gear is aligned coaxially to the geometric spindle axis (14). [6] Spindle drive (1) according to one of the preceding claims, characterized by that the spindle (10) and the motor drive arrangement (6) are arranged directly one behind the other along the geometric spindle axis (14). [7] Spindle drive (1) according to one of the preceding claims, characterized bythat the spindle nut (11) is tubular with an inner diameter which is at least slightly larger than the corresponding extent of the part of the motor drive arrangement (6) enclosed by the spindle nut (11). [8] Spindle drive (1) according to one of the preceding claims, characterized by that the motor drive arrangement (6) has a tubular drive housing (17) over which the spindle nut (11) slides with play during the retraction movement (12), preferably that a particularly annular sliding arrangement (18) is provided on the spindle nut (11) and slides on the drive housing (17), preferably that the sliding arrangement (18) is located at an axial end of the spindle nut (11). [9] Spindle drive (1) according to one of the preceding claims, characterized bythat the spindle nut (11) engages with the motor drive arrangement (6), in particular with a drive housing (17) of the motor drive arrangement (6), in a rotationally secure manner. [10] Spindle drive (1) according to one of the preceding claims, characterized by that one drive connection (8) is connected to one end of the spindle nut (11), that the other drive connection (9) is connected to the motor drive arrangement (6), in particular to a drive housing (17) of the motor drive arrangement (6), and that both drive connections (8, 9) are located on the geometric spindle axis (14). [11] Spindle drive (1) according to one of the preceding claims, characterized by that the spring arrangement (21) is designed as a helical spring arrangement, in particular as a helical compression spring arrangement, which is aligned concentrically to the geometric spindle axis (14) and which encloses the spindle nut (11). [12] Spindle drive (1) according to claim 11, characterized by that the helical spring arrangement (21) has at least one helical compression spring with spring wire of angular cross-section, in particular rectangular or square cross-section. [13] Flap arrangement of a motor vehicle with a flap (2) for closing a flap opening (3) and with at least one spindle drive (1) assigned to the flap (2) according to one of the preceding claims. [14] Flap arrangement according to claim 13, characterized by that the at least one spindle drive (1) is arranged laterally of the flap opening (3), in particular in a gutter (4), preferably that two spindle drives (1) are provided which are arranged on opposite sides of the flap opening (3).

Images