Toothed belt for transmitting tensile and compressive forces, and drive device with such a toothed belt

Abstract

A toothed belt (1) for transmitting tensile and compressive forces in its longitudinal direction and a drive device (6) with such a toothed belt are proposed. The toothed belt is to be designed in a multi-component composite construction with the belt teeth (2) as one component and a belt back (3) facing away from the belt teeth as a further component, wherein the belt back is formed by a metal profile segmented in the longitudinal direction of the belt, the profile segments (5) of which are spaced apart from each other when the toothed belt is stretched longitudinally and, when the belt teeth are convexly curved longitudinally, abut each other in a way that prevents further longitudinal bending, and wherein the belt teeth have a metallic surface.

Description

[0001] The invention relates to a toothed belt for transmitting tensile and compressive forces and a drive device with such a toothed belt. The drive device is, in particular, part of a door drive for opening and closing a motor vehicle door.

[0002] The timing belt is of multi-component composite construction, with the belt teeth as one component and a belt back facing away from the teeth as another component. The belt back is formed by a metal profile segmented in the longitudinal direction of the belt. When the timing belt is stretched lengthwise, the profile segments are spaced apart from one another, and when the belt teeth are convexly curved longitudinally, they rest against each other, preventing further longitudinal bending. Such a timing belt is known from US 5,692,984 A.

[0003] Autonomous, i.e., driverless, vehicles must be able to perform the entire opening and closing process of their doors without manual intervention. Without a door 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 door actuators are required. These actuators use a drive motor to operate a power transmission element that is attached between the door and a fixed point on the vehicle body, fully opening and closing the door.

[0004] Such a power transmission element can be a toothed belt that transmits both tensile and compressive forces, as proposed in DE 10 2023 124 237 A1.

[0005] The present invention is based on the objective of constructively improving a toothed belt of the type mentioned above and a drive device with such a toothed belt.

[0006] The solution to this problem with regard to the timing belt is that the belt teeth have a metallic surface.

[0007] Compared to the timing belt proposed in the aforementioned application, which consists at least largely of elastomer material, the present timing belt is considerably less limited in its ability to transmit compressive forces due to its metallic backing. This is primarily attributable to the material properties of the elastomer, such as its low modulus of elasticity and low yield strength, which necessitate a comparatively large belt cross-sectional area to achieve sufficient (arc) stability. Furthermore, the toothing of the pure elastomer belt has a limited power transmission capacity, since even with a sufficient cross-sectional area, the low modulus of elasticity promotes deflection and lifting of the teeth from the drive pinion.Furthermore, the large cross-sectional area of ​​the elastomer belt has a negative effect on belt flexibility at low temperatures, whereas at high temperatures it promotes settling / creep of the elastomer material.

[0008] Consequently, the toothed belt according to the invention enables - in addition to high pressure force transmission - a significantly reduced installation space requirement, a significantly increased durability of the teeth and a much wider temperature operating range, while maintaining the same stability properties.

[0009] The solution to this problem with regard to the drive device is achieved by comprising, as a power transmission element, such a toothed belt and furthermore a toothed belt pulley, which drives the toothed belt with an external toothing in engagement with the belt teeth in both longitudinal directions of the belt, and a belt support located on the back of the belt, which supports the drive forces of the toothed belt pulley acting in the transverse direction of the belt.

[0010] Advantageous embodiments of the invention are the subject of the dependent claims.

[0011] Further features of the invention will become apparent from the following description and the figures, which illustrate exemplary embodiments of toothed belts or drive devices with such toothed belts for operating the doors of a motor vehicle. Unless otherwise stated, identical or functionally equivalent components or features are designated with the same reference numerals. Toothed belts whose teeth have an elastomeric surface are not according to the invention. The figures show: Fig. 1a: a first toothed belt in perspective view; Fig. 1b: the first timing belt in longitudinal section through the belt teeth; Fig. 1c: the first timing belt in cross-section II according to Fig. 1b; Fig. 1d: a part of a drive device with the first toothed belt, a pulley and a belt support in perspective view; Fig. 1e: the part of the drive device according to Fig. 1d in side view; Fig. 1f: a part of a drive device with the first toothed belt and the pulley according to Fig. 1d and an alternative strap support in perspective view; Fig. 1g: the part of the drive device according to Fig. 1d in the belt cross-section; Fig. 2a: a second timing belt in perspective view; Fig. 2b: the second timing belt in longitudinal section through the belt teeth; Fig. 2c: the second timing belt in cross-section II according to Fig. 2b; Fig. 3: a part of a drive device with a third toothed belt, a pulley and a belt support in the belt cross-section; Fig. 4: a part of a drive device with a fourth toothed belt, a pulley and a belt support in the belt cross-section; Fig. 5: a part of a drive device with a fifth toothed belt, a pulley and a belt support in the belt cross-section.

[0012] The Fig. Figures 1a to 1c show the first toothed belt 1 from different perspectives. The toothed belt 1, which transmits not only tensile but also compressive forces, is constructed of a multi-component composite material and comprises a toothed section 2 as one component and a belt back 3, located opposite the toothed section 2, as another component. The toothed section 2 consists of a reinforced elastomer material, the reinforcement being formed by a tensile member / cord and / or a fabric embedded within the elastomer. The belt back 3 is formed by a metal profile segmented in the longitudinal direction of the belt, which transmits compressive forces and simultaneously provides a defined, flexible support structure. The metal profile consists of a top section 4 parallel to the toothed section 2 and a plurality of profile segments 5 extending perpendicularly from it, which are spaced apart from one another when the toothed belt 1 is stretched longitudinally.With a convex longitudinally curved belt toothing 2, the lower edges of the profile segments 5 facing away from the belt toothing 2 approach each other and eventually abut each other, blocking any further longitudinal bending. These two states are in . Fig. Figure 1e shows a superimposed representation of a longitudinally stretched and a longitudinally bent toothed belt 1. The stability and simultaneous flexibility of the toothed belt 1 depend, among other things, on the mutual spacing and the pitch of the profile segments 5.

[0013] The belt back 3, with its curved shape, exhibits high stability while remaining flexible in the reverse direction. The cross-sectional shape of the belt back 3 is designed to absorb and transmit high compressive forces in a curved form. Thanks to the metallic material with its high modulus of elasticity and high yield strength, maximum stability is achieved with minimal material usage. For applications with lower load-bearing requirements, a plastic version of the belt back 3 is also available.

[0014] The belt back 3 continues to have a load-bearing function for the belt teeth 2. This is shown in the Fig. Figures 1d to 1f illustrate a part of a drive device 6 with the toothed belt 1 described above, a toothed belt pulley 7, and a belt support 8. The toothed belt pulley 7, which can be made of metal, rubberized metal, or plastic to ensure optimal power transmission with minimal noise and smooth running, has an external tooth 9 that engages with the belt teeth 2 and drives the toothed belt 1 in both longitudinal directions. The belt support 8 rests against the metal profile on the side facing away from the belt teeth 2 and supports the drive forces acting on the toothed belt pulley 7 in the transverse direction of the belt, thus preventing the belt teeth 2 from lifting off / rising out of the external tooth 9 and ensuring optimal power transmission via the tooth engagement.

[0015] In the exemplary embodiment according to the Fig. 1d, Fig. 1e and Fig. 1g two support rollers 10 arranged on both sides of the profile segments 5, on which the upper beam 4 rolls and which deflect the retracted toothed belt 1 backwards (sa Fig. 1g). Fig. Figure 1f shows a constructive alternative design of the belt support 8 with two sliding shoes 11 on which the upper belt 4 slides.

[0016] The belt teeth 2 are bonded to the belt back 3 by means of a material bond, in this case by means of a vulcanization or bonding process. In addition to quiet operation, the elastomer-metal composite exhibits acoustic decoupling and damping properties. Alternatively, a [missing information] is also possible. Fig. The embodiment of a second timing belt 1 shown in Figures 2a to 2c is possible, in which the belt teeth 2 are also formed by a sheet metal part 12 and consequently have a metallic, rather than an elastomeric, surface. The sheet metal part 12 is also positively connected to the belt back 3 and, in this case, welded or brazed. In both cases, the material bond can be supplemented by a positive-locking connection.

[0017] The toothing, in both elastomer-metal and metal-metal composites, is designed to eliminate or minimize any play in the tooth engagement. Preloaded toothing is also possible.

[0018] The Fig. 3, Fig. 4 to Fig. 5 show the T-shaped cross-section of the Fig. 1g alternative cross-sectional profiles of the belt back 3.

[0019] Fig. Figure 3 shows a metal profile with a U-shaped cross-section, which is closed towards the belt teeth 2, wherein a single support roller 10 is accommodated inside the U-profile, on which the upper belt 4 rolls.

[0020] Fig. Figure 4 shows a metal profile with a trapezoidal cross-section, which widens towards the belt teeth 2, with two support rollers 10 rolling on the non-parallel trapezoidal sides of the profile segments 5.

[0021] Fig. Figure 5 shows a metal profile with a rectangular cross-section, wherein the undersides of the profile segments 5 roll on a single support roller 10.

Claims

[1] Toothed belt (1) for transmitting tensile and compressive forces in its longitudinal direction, wherein the toothed belt (1) is designed in a multi-component composite construction with the belt teeth (2) as one component and a belt back (3) facing away from the belt teeth (2) as a further component, and the belt back (3) is formed by a metal profile segmented in the longitudinal direction of the belt, the profile segments (5) of which are spaced apart from each other when the toothed belt (1) is stretched longitudinally and, when the belt teeth (2) are convexly curved longitudinally, lie against each other in a blocking manner against further longitudinal bending, characterized by , that the belt teeth (2) have a metallic surface. [2] Timing belt (1) according to claim 1, characterized by , that the belt teeth (2) are formed by a sheet metal part (12). [3] Timing belt (1) according to claim 1 or 2, characterized by that the metal profile has a T-shaped cross-section. [4] Timing belt (1) according to any one of claims 1 to 3, characterized by that the metal profile has a U-shaped cross-section. [5] Timing belt (1) according to any one of claims 1 to 3, characterized by that the metal profile has a rectangular cross-section. [6] Timing belt (1) according to any one of claims 1 to 3, characterized by that the metal profile has a trapezoidal cross-section. [7] Drive device (6) comprising a toothed belt (1) according to one of the preceding claims, a toothed belt wheel (7) which drives the toothed belt (1) with an external toothing (9) engaging with the belt teeth (2) in both belt longitudinal directions, and a belt support (8) resting against the metal profile which supports the drive forces of the toothed belt wheel (7) acting in the belt transverse direction. [8] Drive device (6) according to claim 7, characterized by that the belt support (8) either rolls or slides on the metal profile.

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