Drive mechanism for a vehicle door

Abstract

The invention relates to a drive mechanism (1) for a vehicle door, comprising: - an open-ended chain (2) which transmits tensile and compressive forces in a longitudinal direction (z) of the chain and is composed of a plurality of chain links (9, 10) which are in articulated contact with one another and each have a chain tooth (11) projecting in a first transverse direction (x) of the chain, thereby forming a toothed profile of the chain, wherein the longitudinal direction of the chain and the first transverse direction of the chain span a plane of curvature in which the chain can bend in both directions of curvature during operation; - a sprocket (7) which meshes with the toothed profile (12) of the chain and which longitudinally divides the chain into a load strand and a return strand, wherein the load strand extends from the sprocket to a first chain end (3) which transmits the tensile and compressive forces, and wherein the return strand extends from the sprocket to the second chain end (8); - and a motor which rotationally drives the sprocket (7). Bending of the chain during operation in the direction of curvature facing away from the sprocket is limited by contact between the chain links outside the pivot joints (13) thereof, wherein each of the chain links has an opening (25) extending through it in the longitudinal direction of the chain, and the chain comprises a pre-tensioned tensile strand (24) which extends between the chain ends, and onto which the chain links are threaded by means of their openings.

Description

[0001] P250535 1

[0002] Drive mechanism for a vehicle door

[0003] The invention relates to a drive mechanism for opening and closing a door of a motor vehicle, comprising:

[0004] - an open chain that transmits tensile and compressive forces in the longitudinal direction of the chain and is composed of a plurality of chain links that contact each other by means of a pivot joint, each with a chain tooth rising in a first transverse direction of the chain, forming a toothing of the chain, wherein the longitudinal direction of the chain and the first transverse direction of the chain define a plane of curvature in which the chain bends in both directions of curvature during operation,

[0005] - a sprocket meshing with a toothed section of the chain, which longitudinally divides the chain into a load section and an slack section, wherein the load section extends from the sprocket to a first chain end which transmits the tensile and compressive forces and wherein the slack section extends from the sprocket to the second chain end,

[0006] - and a motor that drives the chain wheel.

[0007] Autonomous, i.e., driverless, vehicles must be able to perform the entire opening and closing process of their doors without manual intervention. Without a drive mechanism, also known as a "smart door," they would be unable to continue their journey if a passenger left the door open after getting in or out. Therefore, smart doors are a prerequisite for fully autonomous driving. To make a vehicle door "smart" in this sense, appropriate drive mechanisms are required. These mechanisms use a drive motor to actuate a power transmission element located between the door and a fixed point on the vehicle body, fully opening and closing the door.

[0008] DE 10 2022 100 510 A1 discloses a drive mechanism with a chain for opening and closing a door of a motor vehicle.

[0009] DE 202006017 304 U1 discloses a back-stiff chain that transmits tensile and compressive forces in the longitudinal direction of the chain.

[0010] A generic drive mechanism with a chain as a power transmission element is known from DE 102023124237 A1.P250535 2

[0011] The present invention is based on the objective of adapting a drive mechanism of the type mentioned above to the specific requirements of power transmission. The suitability of the drive mechanism is not limited to opening and closing a vehicle door, but, with any necessary modifications, also extends to driving other components such as a front or rear hatch, a sliding or panoramic sunroof, or a door window. Likewise, the use of the drive mechanism is not limited to autonomous vehicles.

[0012] The solution to this problem is achieved by limiting the operational curvature of the chain in the direction of curvature away from the sprocket by mutual contact of the chain links outside their pivot joints, wherein the chain links are each penetrated by an opening in the longitudinal direction of the chain and the chain has a pre-tensioned tension member extending between its chain ends, on which the chain links are threaded at their openings.

[0013] In operating mode, i.e., in the intended use state of the drive mechanism, the chain's compressive force is transmitted via the mutual pressure contact of the chain links. Excessive chain curvature, and thus operational buckling of the chain in the direction prone to buckling, is prevented by the fact that the chain links are in pressure contact either also or exclusively outside the pivot joints, so that further joint rotation is blocked and consequently the operational chain curvature is limited. This results in sufficiently high arc stability of the chain and enables the buckling-proof transmission of even high compressive forces. The chain is concavely curved in one direction on the side facing away from the sprocket. In other words, the center of curvature of the chain is located on the side facing away from the sprocket in this curvature state.

[0014] Advantageous embodiments of the invention are the subject of the dependent claims.

[0015] Further features of the invention will become apparent from the following description and the figures, in which an embodiment of a drive unit according to the invention is shown.

[0016] The mechanism for opening and closing a motor vehicle door is explained using various illustrations. These show:

[0017] Figure 1: the drive mechanism in a perspective front view:

[0018] Figure 2: the drive mechanism in a perspective rear view:

[0019] Figure 3: the drive mechanism in perspective longitudinal section through the chain with the vehicle door closed;

[0020] Figure 4: the drive mechanism in perspective longitudinal section through the chain with the vehicle door open;

[0021] Figure 5: a chain housing of the drive mechanism as a perspective and open section;

[0022] Figure 6: the section according to Figure 5 without chain and guide roller;

[0023] Figure 7: the chain of the drive mechanism in perspective detail view;

[0024] Figure 8: a perspective view of the chain end on the last side;

[0025] Figure 9: a perspective partial section of the chain end on the empty-side;

[0026] Figure 10: the sprocket and the chain meshing with it in a top view.

[0027] The drive mechanism 1, shown in various views in Figures 1 to 4, serves for both fully automatic and assisted opening and closing of a vehicle door of an autonomous vehicle. The core of the drive mechanism 1 is an open chain 2, which transmits both tensile and compressive forces in its longitudinal direction z at a first chain end 3. The force transmission is effected by means of a connecting piece 4 at the first chain end 3, which can be screwed to a body pillar supporting the vehicle door, such as the vehicle's A-pillar. The drive mechanism 1 itself is mounted in the vehicle door. The chain 2 is driven by a motor, which in this case is an electric motor in a drive housing 5P250535 4.

[0028] The drive housing 5 is connected to a chain housing 6, in which a sprocket 7, driven by the motor and meshing with the teeth of the chain 2, is rotatably mounted. The sprocket 7 divides the chain 2 longitudinally into a first chain section, which is the load-bearing section transmitting the tensile and compressive forces, and a second chain section, which is a slack section (neglected for friction and inertial forces). The load-bearing section extends from the sprocket 7 to the connecting piece 4, and the slack section extends from the sprocket 7 to the free second chain end 8.

[0029] The chain 2, which will be explained in more detail later with reference to Figures 7 to 10, is composed of a multitude of chain links 9 and 10 that contact each other via pivot joints, each with a chain tooth 11 rising in a first transverse chain direction x, thus forming the chain teeth 12. The second transverse chain direction is denoted by y. The longitudinal chain direction z and the first transverse chain direction x define a plane of curvature in which the chain 2 bends in both directions during operation. The loaded side and the slack side are each concavely curved in the direction of curvature away from the sprocket 7, i.e., the centers of curvature lie on the side of the chain facing away from the sprocket 7. Within the area of ​​wrap around the sprocket 7, the chain 2 is convexly curved in this direction of curvature (opposite direction), i.e. the center of curvature lies in this area on the side of the chain facing the sprocket 7.Operational buckling of the chain 2 is prevented by limiting the concave curvature, whereby the limitation is determined by mutual contact of the chain links 9 and 10 outside their pivot joints 13, cf. Figure 10.

[0030] Figures 3 and 4 each show the drive mechanism 1 in an open longitudinal section view through the chain housing 6. In Figure 3, the drive mechanism 1 is located at the operating point of the fully closed vehicle door, and in Figure 4, it is located at the operating point of the fully open vehicle door. The vehicle door is opened by rotating the sprocket 7 in the direction of rotation shown on the sprocket 7 in Figure 3. This shortens the slack side of the chain 2 and increases the distance between the chain housing 6 and the connecting piece 4, i.e., the body pillar with the load side. During normal opening, when the vehicle door resists opening, the chain 2 transmits compressive forces via the load side. The vehicle door is closed by rotating the sprocket 7 in the direction of rotation shown on the sprocket 7 in Figure 3.

[0031] The direction of rotation is shown in Figure 4, whereby the slack side of the chain 2 lengthens and the distance between the chain housing 6 and the connecting piece 4, i.e., the body pillar with the load side, shortens. During a normal closing operation, in which the vehicle door resists closing, the chain 2 transmits tensile forces via the load side.

[0032] The chain housing 6 is essentially cuboid and has an open side 14 through which the loaded side of the chain 2 enters and exits. On the opposite side, a chain box 15, forming part of the chain housing 6, has a comparatively small cross-section. The slack side of the chain 2 is supported in this box in both the first transverse chain direction x and the second transverse chain direction y, and guided in the longitudinal chain direction z. For this purpose, the cross-section of the plastic chain box 15 is essentially complementary to that of the chain 2, which, according to Figure 7, has a predominantly T-shaped cross-section.

[0033] Figures 5 and 6 show further details of the construction of the drive mechanism 1 within the chain housing 6. The sprocket 7 is part of an output shaft 16 that passes through the chain housing 6 in the second transverse direction y of the chain. The output shaft 16 is rotatably mounted in the chain housing 6 in a lower housing part 17 and an associated upper housing part 18. A drive shaft driven by an electric motor is located in the drive housing 5 and drives the output shaft 16 in a coaxial arrangement. The drive housing 5 is optionally connected either—as is the case here—to the lower housing part 17 or to the upper housing part 18, so that the drive connection of the drive shaft can be established either with the (lower) end or with the (upper) other end 19 of the output shaft 7. This allows for the optional and, if necessary,The drive mechanism 1 is mounted in a mirror-symmetrical manner on either a left or right vehicle door, using only identical components. The drive connection is a fully positive-locking plug connection of the drive shaft within the output shaft 7.

[0034] The axis of rotation of the electric motor housed in the drive housing 5 is, in this case, aligned parallel to the plane of curvature of the chain 2. Depending on the installation space requirements for the drive mechanism 1, the motor's axis of rotation can also be aligned differently, for example, perpendicular to the plane of curvature. A gearbox housed in the drive housing 5 translates the drive speed of the electric motor to a demge-P250535 6

[0035] This results in a lower output speed of the sprocket 7 with a corresponding increase in torque. The transmission can be multi-stage and, for example, have a worm gear as the first reduction stage and a spur gear as the second reduction stage.

[0036] The chain 2 is supported on its side facing away from the sprocket 7 by a guide rail 20 located in the chain housing 6 between the upper housing part 18 and the lower housing part 17. The guide rail 20 is supported in the first transverse direction x of the chain and guided in the longitudinal direction z of the chain in a sliding manner. The guide rail 20 consists of a polyamide with embedded solid lubricant (in this case PTFE) to improve its sliding properties. The side of the slack chain facing the sprocket 7 is also supported in the first transverse direction x of the chain by a guide roller 21 located in the chain housing 6 next to the sprocket 7 and guided in a rolling manner in the longitudinal direction z of the chain, i.e., towards the chain case 15.

[0037] In conjunction with Figures 7 and 9, the chain 2 has, in order to limit a longitudinal movement that further shortens the slack side compared to Figure 4, one and, in this case, two mutually symmetrical steps 22, which are oriented towards the end face in the chain's longitudinal direction z and with which the chain 2 abuts a stop 23 of the chain housing 6. The steps 22 are created by the fact that at least one of the chain links 10 – in the second transverse chain direction y – is wider than an adjacent chain link 9 and projects beyond it on both sides. In this case, all chain links 10 adjoining the second chain end 8 have this greater width. The stop 23 on the chain housing 6 comprises two stop parts, which are formed symmetrically to each other on the upper housing part 18 (hidden in Figure 5) and on the lower housing part 17.

[0038] The following explains the structural design of the chain 2, shown in isolation in Figures 7 to 9. The chain links 9 and 10, each with a T-shaped cross-section and mirror-symmetrical to the plane of curvature, extend in the second chain transverse direction y to both sides of the chain teeth 12, which run in the plane of curvature, and in the first chain transverse direction x in the direction away from the chain teeth 12. The steps 22.P250535 7 created by the relatively wide chain links 10 at the second chain end 8 are also clearly visible.

[0039] The tensile forces acting on the chain 2 are transmitted by a tension member 24, which extends under pretension between the chain ends 3 and 8. The chain links 9, 10 each have oval openings 25 on both sides of the chain teeth 12 in the longitudinal direction z of the chain and are threaded onto the tension member 24 at the openings 25. In this case, the tension member is formed from three wire ropes passing through the openings 25, the ends 26 of which are each attached to one of the chain ends 8, 3, and the midpoints 27 of which are each deflected in the opposite direction at the other chain end 3, 8. The deflection is effected at the first chain end 3 by means of a deflector 28 with a semicircular circumferential groove 29, which deflects the wire ropes stacked radially within it. Due to the pretension of the tension member 24, the connecting piece 4 between the deflection piece 28 and the last chain link 9 of the first chain end 3 is held clampingly.The rope ends 26 are attached to the second chain end 8 by crimping the openings 25 of one or, in the case of several, chain links 10 in the case of pre-tensioned wire ropes, and protrude slightly there due to the manufacturing process.

[0040] The tensile strand 24 can be formed by a tensile-resistant plastic fabric or a steel band as an alternative to the wire ropes.

[0041] The narrow chain links 9 and the wide chain links 10 are identical parts and are made of a metallic material with a high modulus of elasticity and a high yield strength. As can be seen in conjunction with Figure 10, the pivot joints 13 of the chain links 9, 10 are each formed by a concave cylindrical segment 30 in the longitudinal direction z of the chain on one of the chain links 9, 10 and a convex cylindrical segment 31 adjacent to it on a chain link 9, 10, with the cylindrical segments 30, 31 extending on both sides of the chain tooth 11 in the second transverse direction y of the chain.

[0042] The operational curvature of the chain 2 is limited by the mutual contact of adjacent chain links 9, 10 outside the pivot joint 13. The concave curvature of the chain 2 outside the wrap area at the sprocket 7 is limited by the contact of mutually facing end faces 32 and 33, which each run on the side of the chain links 9, 10 facing away from the chain tooth 11 and are slightly wedge-shaped apart from each other when the chain 2 is not curved. The convex curvature of the chain 2 within the wrap area at the sprocket 7 is determined by the tooth engagement with the pitch circle of the sprocket 7 and can optionally be adjusted by the contact P250535 8

[0043] mutually facing end faces 34 and 35, which each run on the side of the chain links 9, 10 facing the chain tooth 11 and are also slightly wedge-shaped apart from each other in the case of an uncurved chain 2.

[0044] The pitch circle radius of the sprocket 7, the maximum concave curvature and, if applicable, the maximum convex curvature are dimensioned or limited in such a way that the tension member 24 can be curved to its maximum extent with maximum fatigue strength.

[0045] Another design option is to shape the end faces 32 and / or 33, for example convexly in the chain's longitudinal direction z, such that the end faces 32, 33 do not make full-surface contact, but rather have line or point contact that shifts away from the pivot joint 13 with increasing concave curvature. This contact kinematics, due to the increasing spacing of the cylinder segments 30, 31 with increasing curvature, causes a loss of contact at the pivot joint 13 and consequently an elongation of the tension member 24. The resulting increase in tension of the tension member 24 with the concave curvature gives the chain 2 elastic behavior and prevents sudden contact between the chain links 9, 10.

Claims

P250535 9 Patent claims 1. Drive mechanism (1) for a vehicle door, comprising: - an open chain (2) that transmits tensile and compressive forces in the chain longitudinal direction (z) and is composed of a plurality of chain links (9, 10) that contact each other in a rotatable manner, each with a chain tooth (11) rising in a first chain transverse direction (x) to form a toothing of the chain (2), wherein the chain longitudinal direction (z) and the first chain transverse direction (x) define a plane of curvature in which the chain (2) bends in both directions of curvature during operation, - a sprocket (7) meshing with the chain teeth (12), which longitudinally divides the chain (2) into a load side and an slack side, wherein the load side extends from the sprocket (7) to a first chain end (3) transmitting the tensile and compressive forces and wherein the slack side extends from the sprocket (7) to the second chain end (8), - and a motor that rotates the sprocket (7), characterized in that the operational curvature of the chain (2) in the direction of curvature away from the sprocket (7) is limited by mutual contact of the chain links (9, 10) outside their pivot joints (13), wherein the chain links (9, 10) are each penetrated by an opening (25) in the longitudinal direction (z) of the chain and the chain (2) has a pre-tensioned tension member (24) extending between its chain ends (3, 8), on which the chain links (9, 10) are threaded at their openings (25).

2. Drive mechanism (1) according to claim 1, characterized in that the traction string (24) comprises one or more wire ropes, the rope ends (26) of which are attached to one of the chain ends (8, 3) and the rope centers (27) of which are deflected in a reversing direction at the other of the chain ends (3, 8).

3. Drive mechanism (1) according to claim 2, characterized in that the rope ends (26) are attached to one chain end (8) by crimping the openings (25) of one or more chain links (10).

4. Drive mechanism (1) according to one of the preceding claims, characterized by a chain housing (6) rotatably supporting the sprocket (7) and a da-P250535 10 a guide rail (20) mounted on which the side of the chain (2) facing away from the sprocket (7) is supported in the first transverse chain direction (x) and guided slidingly in the longitudinal chain direction (z).

5. Drive mechanism (1) according to claim 4, characterized by a guide roller (21) received in the chain housing (6) on the side of the sprocket (7), on which the slack side of the chain (2) is supported in the first transverse chain direction (x) and guided in a rolling manner in the longitudinal chain direction (z).

6. Drive mechanism (1) according to claim 4 or 5, characterized in that the chain (2) has a step (22) oriented towards the end face in the chain longitudinal direction (z) in order to limit its longitudinal movement shortening the slack side, with which the chain (2) abuts a stop (23) of the chain housing (6).

7. Drive mechanism (1) according to claim 6, characterized by a chain case (15) forming part of the chain housing (6), in which the slack side of the chain (2) is supported in the first chain transverse direction (x) and in a second chain transverse direction (y) and guided in the chain longitudinal direction (z).

8. Drive mechanism (1) according to claim 7, characterized in that the sprocket (7) is part of an output shaft (16) passing through the chain housing (6) in the second chain transverse direction (y), wherein the motor is accommodated in a drive housing (5) with a drive shaft driven by the motor, which can be selectively connected to one end or the other end (19) of the output shaft (7).

9. Drive mechanism (1) according to claim 8, characterized by a transmission housed in the drive housing (5) which translates the input speed of the motor to a correspondingly lower output speed of the sprocket (7).

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