BELT DRIVE

Description

[0001] The present invention relates to a belt drive according to the preamble of patent claim 1, a drive system with such a belt drive according to patent claim 4 and a vehicle with such a drive system according to patent claim 5.

[0002] In many technical fields, drive systems are used to convert the rotary motion of a drive unit into the rotary motion of an output unit. This can be used to transmit a continuous motion, for example, to transfer the rotation of the drive unit with a combustion engine, a hybrid engine, or an electric motor of a vehicle to the vehicle's wheels. However, changes in the position of the output unit can also be made in this way, for example, to transfer a steering movement of a steering wheel of an electromechanical steering system of a vehicle to its wheels.

[0003] This power transmission can be achieved via a belt drive, which is arranged between the drive unit and the output unit. A belt drive has a belt as the essential element that transmits the load or forces. A belt, which can also be referred to as a drive means, is a flexible band for transmitting power from the belt drive, which in this application is endless. The belt usually runs around a drive pulley of the drive unit and at least one idler pulley of the output unit. Between the two deflection sections of the belt, which engage around the drive pulley and the idler pulley, there are at least two free belt sections, which, depending on the direction of the belt movement, can be referred to as the pulling strand or the load strand, and as the pulled strand or the slack strand. The drive pulley and the idler pulley can also be referred to as pulleys.The idler pulley can also be called an output pulley.

[0004] On its inner side, which is in contact with the drive pulley and the idler pulley, the belt can be smooth (as a flat belt) or profiled (as a V-belt, V-ribbed belt, or timing belt). Round belts are also known.

[0005] The disadvantage of such drive systems with a belt drive is that if the belt is destroyed or torn, e.g. due to misuse, fault, wear or other circumstances, the power transmission between the drive unit and the output unit is completely lost. This means a complete failure of the drive system. As a result, the drive power in a vehicle is no longer available, which can cause the vehicle to stop and come to a standstill. If the belt in the steering system fails as a drive system, the vehicle can no longer be steered, which can pose a danger to the occupants, the surrounding area and other road users.

[0006] DE 103 16 599 A1 describes a transmission device for motor vehicle steering system drives, comprising at least one drive motor with a motor shaft and at least two drive trains, each having a toothed belt pulley on the motor shaft, a toothed belt rim on a steering gear, and a toothed belt. The toothed belt connects the toothed belt pulley and the toothed belt rim of a drive train, and the tooth pitches of the toothed belt pulley, toothed belt rim, and toothed belt are identical for each drive train. The tooth pitches of the drive trains are offset from one another. This results in particularly smooth and quiet operation of the transmission. DE 102004019313 A also describes a belt drive.

[0007] An object of the present invention is to provide a belt drive of the type described above, the functionality of which can be guaranteed even in the event of belt failure. Additionally or alternatively, the noise generation of such a belt drive should be reduced, in particular to increase driving comfort for the user of a vehicle with such a belt drive. At the very least, an alternative to known belt drives of this type should be provided.

[0008] The object is achieved according to the invention by a belt drive having the features of patent claim 1, by a drive system having the features of patent claim 4, and by a vehicle having the features of patent claim 5. Advantageous further developments are described in the subclaims.

[0009] Thus, the present invention relates to a belt drive comprising a first drive roller configured to be fixedly connected to a drive unit, preferably to a shaft of a drive unit, a first output roller configured to be fixedly connected to an output unit, preferably to a shaft of an output unit, and a first belt connecting the first drive roller to the first output roller in a force-transmitting manner. Belt drives of this type are known, as described above.

[0010] The belt drive further comprises: a second drive roller, which is designed to be fixedly connected to the drive unit, preferably to the shaft of the drive unit; a second output roller, which is designed to be fixedly connected to the output unit, preferably to the shaft of the output unit; and a second belt, which connects the second drive roller to the second output roller in a force-transmitting manner. Depending on the application, more than two drive rollers, two output rollers, and two belts can be used to design and / or enhance the properties and advantages described below.

[0011] In this way, the power can be transmitted partially or even completely by each of the two belts alone. In any case, partial to complete redundancy can be created so that if one of the two belts fails, the other remaining belt can take over power transmission at least partially or completely. This can ensure at least temporary operation of the now overloaded remaining belt as an emergency feature, so to speak, in order to bring the drive system with the drive unit, the output unit and the remaining belt into a safe state, such as a stop, in a controlled manner. If both belts are designed with sufficient strength, operation can also continue without restriction, apart from the loss of redundancy, as will be described in more detail below.

[0012] According to one aspect of the present invention, the belt drive has precisely one first drive roller and one second drive roller, precisely one first output roller and one second output roller, and precisely one first belt and one second belt. This allows the previously described properties of using multiple belts for a belt drive to be achieved with the smallest possible number of drive rollers, output rollers, and belts. This can keep the additional costs for the other components of the belt drive low. This also applies to the resulting assembly costs and the required installation space.

[0013] According to the invention, the first belt and the second belt are each designed for the sole transmission of power between the respective drive pulley and the respective output pulley. This can enable complete redundancy of the two belts, so that if one belt fails, the operation of the belt drive and the corresponding drive system can continue with the remaining belt. This can ensure safe operation of the belt drive or the drive system even if one belt fails, whereby previously existing redundancy must be dispensed with at least until the second belt has been restored. In this way, for example, a vehicle could reach a workshop safely and leave it with the redundancy of the belt drive restored. Due to the lost redundancy, the journey to the workshop could, for example, be made at a reduced maximum speed for safety reasons.

[0014] According to the invention, the drive rollers are designed as helical drive gears, the output rollers as helical output gears and the belts as helical toothed belts, wherein the first drive gear, the first output gear and the first toothed belt have a first helical toothing which is aligned in the opposite direction to a second helical toothing of the second drive gear, the second output gear and the second toothed belt.

[0015] This aspect of the present invention is based on the finding that a toothed belt can be used as a belt in such a drive system. This requires that the drive rollers and the driven rollers are designed as gears and each have a corresponding helical toothing, i.e., that the teeth of the drive rollers and the driven rollers are not arranged parallel to the axis of rotation, but at a predetermined angle to the axis of rotation of well under 90°. This makes it possible to reduce the polygon effect and thus the tooth meshing frequency, which can improve the smoothness of the belt drive and reduce the noise generated by the belt drive.

[0016] Since this can have only a comparatively small effect with a single belt, it is advantageous to apply two opposing helical gears to the present belt drive according to the invention. This can enhance the effect of improving the smooth running of the belt drive and reducing the noise generated by the belt drive, which can be achieved with helical gearing per se.

[0017] According to the invention, the first helical gearing and the second helical gearing have different pitches. In other words, the distances between all teeth of the respective helical gearing are selected differently between the two drive pulleys, the two output pulleys, and the two belts. This also further enhances the effect of improving the smooth running of the belt drive and reducing the noise generated by the belt drive, which can be achieved by helical gearing itself, since the teeth of the belts now meet the corresponding teeth of the respective drive pulley or output pulley at different times, thus allowing the aforementioned effect to be applied more evenly.

[0018] According to the invention, the first helical gearing and the second helical gearing have different helixes. In other words, the two helical gearings have different angles to the rotation axis. This also further enhances the effect of improving the smooth running of the belt drive and reducing the noise generated by the belt drive, which can be achieved with helical gearing per se, since the teeth of the belts now meet the corresponding teeth of the respective drive pulley or output pulley with different mechanical contact surfaces, thus generating or reducing different noise levels.

[0019] According to a further aspect of the present invention, the drive rollers and / or the output rollers are formed as a single piece. This can, for example, reduce the number of components of the belt drive that need to be handled during assembly, which can simplify and accelerate assembly. This can also ensure, for example, a consistent arrangement of the helical gears relative to one another.

[0020] The present invention also relates to a drive system comprising a drive unit, an output unit, and a belt drive as described above, which connects the drive unit and the output unit to one another in a force-transmitting manner. This allows the previously described properties and advantages of a belt drive according to the invention to be implemented and utilized in a corresponding drive system.

[0021] The present invention also relates to a vehicle with a drive system as described above. This allows the above-described properties and advantages of a drive system according to the invention to be implemented and utilized in a corresponding vehicle.

[0022] According to one aspect of the present invention, the drive system is designed to transmit a steering movement. Thus, the properties described above can be implemented and utilized, particularly with regard to improving safety and / or the acoustic behavior of the drive system, specifically as a steering system, since a failure of a vehicle's steering system can pose a particularly high safety risk, and the steering movements can continuously lead to noise from the belt drive.

[0023] Several embodiments and further advantages of the invention are explained below in conjunction with the following figures. Fig. 1 is a schematic plan view of a belt drive according to the invention according to a first embodiment in a drive system according to the invention; Fig. 2 is a schematic plan view of a belt drive according to the invention according to a second embodiment in a drive system according to the invention; Fig. 3 is a schematic plan view of a belt drive according to the invention according to a third embodiment in a drive system according to the invention; and Fig. 4 is a schematic plan view of a belt drive according to the invention according to a fourth embodiment in a drive system according to the invention.

[0024] Fig. 1shows a schematic plan view of a belt drive 3 according to the invention according to a first embodiment of a drive system according to the invention.

[0025] The drive system comprises a drive unit 1 with a shaft 10, which can be driven by the drive unit 1 about a rotational axis A in a rotational direction B. The drive system further comprises an output unit 2 with a shaft 20, which can be driven by the output unit 2 about a rotational axis C in a rotational direction D. Thus, a rotational movement about the rotational axis C in the rotational direction D can be transmitted from the output unit 2 to another unit (not shown) in order to move it rotationally.

[0026] In order to transmit the rotational movement of the drive unit 1 about the rotation axis A in the rotation direction B to the output unit 2, the drive unit 1 is connected to the output unit 2 in a force-transmitting manner by means of the previously mentioned belt drive 3. For this purpose, the belt drive 3 has a first drive roller 30 and a second drive roller 31, which are arranged next to one another in a fixed position on the shaft 10 of the drive unit 1. Correspondingly, the belt drive 3 has a first output roller 32 and a second output roller 33, which are arranged next to one another in a fixed position on the shaft 20 of the output unit 2. The belt drive 3 has a first belt 34, which is endlessly closed and wraps around the first drive roller 30 and the first output roller 32.Furthermore, the belt drive 3 has a second belt 35, which is also endlessly closed and wraps around the second drive roller 31 and the second output roller 33.

[0027] In this way, the rotational movement of the shaft 10 of the drive unit 1 can be transmitted via the two belts 34, 35 in a direction of movement E together to the shaft 20 of the output unit 2, so that in the event of a failure of one of the two belts 34, 35, the transmission of the rotational movement or the force can in principle continue.

[0028] If each belt 34, 35 is designed to be too weak for the sole transmission of the rotational movement or the force, then at the time of failure of one belt 34, 35 the functionality of the belt drive 3 can be maintained for a certain period of time due to the remaining overloaded belt 34, 35, which may be sufficient to bring the drive system into a safe state.

[0029] If each belt 34, 35 is designed to transmit the rotational movement or power alone, then this can be referred to as a redundant belt drive 3, since if one belt 34, 35 fails, the remaining belt 34, 35 is sufficient to continue the operation of the belt drive 3 permanently, albeit without redundancy. This can also be used in this case to transfer the drive system to a safe state while still being able to safely utilize the drive system's functionality.

[0030] In order to simultaneously improve the smooth running of the belt drive 3 and reduce the noise generated by the belt drive 3, the first drive roller 30 is designed as the first drive gear 30, the second drive roller 31 as the second drive gear 31, the first output roller 32 as the first output gear 32, the second output roller 33 as the second output gear 33, the first belt 34 as the first toothed belt 34, and the second belt 35 as the second toothed belt 35. The first drive gear 30, the first output gear 32, and the first toothed belt 34 have a first helical toothing 36, which is aligned in the opposite direction to a second helical toothing 37 of the second drive gear 31, the second output gear 33, and the second toothed belt 35.As a result, the effect of improving the smooth running of the belt drive 3 and reducing the noise generated by the belt drive 3, which can be achieved by helical gearing 36, 37, can be utilized in the belt drive 3 according to the invention. The use of helical gearing 36, 37 on each toothed belt 34, 35 can further enhance this effect.

[0031] In the first embodiment, the two drive gears 30, 31, the two driven gears 32, 33 and the two toothed belts 34, 35 have Fig. 1 The individual teeth of the helical gears 36, 37 have the same pitch, i.e., the same distance from one another in the direction of movement E. The teeth of the helical gears 36, 37 are also directly aligned with one another, mirror images of one another, so to speak. Furthermore, the teeth of the helical gears 36, 37 have the same angle relative to the rotation axes A, C of the shafts 10, 20.

[0032] Fig. 2shows a schematic plan view of a belt drive 3 according to the invention according to a second exemplary embodiment of a drive system according to the invention. In this case, the teeth of the helical gears 36, 37 of the two drive gears 30, 31, the two output gears 32, 33, and the two toothed belts 34, 35 also have the same pitch, i.e., the same distance from one another in the direction of movement E. The teeth of the helical gears 36, 37 also again have the same angle relative to the rotation axes A, C of the shafts 10, 20.

[0033] However, the first helical gear 36 has a pitch offset compared to the second helical gear 37, ie the first helical gear 36 begins in the direction of movement E at a different position of the first drive gear 30 or the first output gear 32 than the second helical gear 37. As a result, the effect of improving the smooth running of the belt drive 3 and reducing the noise generation of the belt drive 3 can be influenced and improved.

[0034] Another advantage here is that by using two toothed belts 34, 35, which are helically toothed in opposite directions and mounted with offset teeth on the two drive gears 30, 31 and the two output gears 32, 33, the load in the transverse direction Y in the center of the belt in the direction of movement E can be reduced or even avoided. High gap loads caused by opposing transverse forces can be prevented. A poor fit of the toothed belts 34, 35 to the two drive gears 30, 31 and the two output gears 32, 33, as well as the risk of the flank only being optimally seated on one toothing side, are prevented by the two-part design.

[0035] Furthermore, the timing belts 34, 35 can be manufactured with large, counter-rotating helical teeth using conventional manufacturing processes, e.g., the push-through process for rubber timing belts. This allows the timing belts 34, 35 to be manufactured significantly more cost-effectively. The same applies to the two drive gears 30, 31 and the two output gears 32, 33, as they do not have to be manufactured from a single component. Nevertheless, the acoustic advantages remain.

[0036] Fig. 3 shows a schematic plan view of a belt drive 3 according to the invention according to a third embodiment of a drive system according to the invention.

[0037] In this case, the teeth of the helical gears 36, 37 again have the same angle relative to the rotation axes A, C of the shafts 10, 20. However, the teeth of the helical gears 36, 37 of the two drive gears 30, 31, the two output gears 32, 33, and the two toothed belts 34, 35 have a different pitch, i.e., different distances from one another in the direction of movement E. This can influence and improve the effect of improving the smooth running of the belt drive 3 and reducing the noise generated by the belt drive 3.

[0038] Fig. 4shows a schematic plan view of a belt drive 3 according to the invention according to a fourth exemplary embodiment of a drive system according to the invention. In this case, the teeth of the helical gears 36, 37 of the two drive gears 30, 31, the two output gears 32, 33, and the two toothed belts 34, 35 again have the same pitch, i.e., the same distance from one another in the direction of movement E. The teeth of the helical gears 36, 37 are also directly aligned with one another, so to speak, mirror images.

[0039] However, in this case, the teeth of the helical gears 36, 37 have different angles relative to the rotational axes A, C of the shafts 10, 20, so that the first helical gear 36 and the second helical gear 37 have different helixes. This can also influence and improve the effect of improving the smooth running of the belt drive 3 and reducing the noise generated by the belt drive 3.

[0040] The previously described properties and advantages of a belt drive 3 according to the invention and of a drive system according to the invention can be used particularly advantageously in a vehicle, for example in a steering system for transmitting a steering movement as a drive system, both to ensure or at least reduce its reliability and to reduce the noise development at this point, which can be generated by the steering movements that are usually required on a regular basis.

[0041] Due to the increasing use of steer-by-wire systems, especially in electric vehicles, the application in a steering system may become particularly important in order to improve and ensure the safety of such systems. Furthermore, any noise generated by electric vehicles can be perceived particularly clearly by the occupants, as these noises cannot be drowned out by the operating noise of a combustion engine. This can apply to both human-driven vehicles and autonomous vehicles. List of reference symbols (part of the description)

[0042] ARotation axis of the drive unit 1 BRotation direction of the drive unit 1 CRotation axis of the output unit 2 DRotation direction of the output unit 2 EDirection of movement of the belt drive 3 1Drive unit 10Shaft of drive unit 1 2Output unit 20Shaft of output unit 2 3Belt drive 30First drive pulley; first drive gear 31Second drive pulley; second drive gear 32First driven pulley; first driven gear 33Second driven pulley; second driven gear 34First (toothed) belt 35Second (toothed) belt 36First helical gear 37Second helical gear

Claims

1. Belt drive (3) having a first drive pulley (30), which is designed to be fixedly connected to a drive unit (1), preferably to a shaft (10) of a drive unit (1), having a first output pulley (32), which is designed to be fixedly connected to an output unit (2), preferably to a shaft (20) of an output unit (2), and having a first belt (34), which connects the first drive pulley (30) force-transmittingly to the first output pulley (32), having a second drive pulley (31), which is designed to be fixedly connected to the drive unit (1), preferably to the shaft (10) of the drive unit (1), having a second output pulley (33), which is designed to be fixedly connected to the output unit (2), preferably to the shaft (20) of the output unit (2), and having a second belt (35), which connects the second drive pulley (31) force-transmittingly to the second output pulley (33), wherein the drive pulleys (30, 31) are designed as helically toothed drive gearwheels (30, 31), the output pulleys (32, 33) as helically toothed output gearwheels (32, 33) and the belts (34, 35) as helically toothed toothed belts (34, 35), and wherein the first drive gearwheel (30), the first output gearwheel (32) and the first toothed belt (34) have a first helical toothing (36), which is oriented in the opposite direction to a second helical toothing (37) of the second drive gearwheel (31), the second output gearwheel (33) and the second toothed belt (35), characterized in that the first helical toothing (36) and the second helical toothing (37) have different slopes, and in that the first belt (34) and the second belt (35) are each designed to transmit force by themselves between the respective drive pulley (30; 31) and the respective output pulley (32; 33), and in that the first helical toothing (36) and the second helical toothing (37) have different pitches.

2. Belt drive (3) according to Claim 1, characterized by precisely one first drive pulley (30) and one second drive pulley (31), precisely one first output pulley (32) and one second output pulley (33), and precisely one first belt (34) and one second belt (35).

3. Belt drive (3) according to either of the preceding claims, characterized in that the drive pulleys (30, 31) are formed in one piece, and / or the output pulleys (32, 33) are formed in one piece.

4. Drive system having a drive unit (1), having an output unit (2), and having a belt drive (3) according to any one of the preceding claims, which connects the drive unit (1) and the output unit (2) force-transmittingly to each other.

5. Vehicle having a drive system according to Claim 4.

6. Vehicle according to Claim 5, characterized in that the drive system is designed to transmit a steering movement.