DE102013110397A1 - Pulley, belt, belt drive and steering system, and method of making a pulley and a belt - Google Patents

Abstract

A pulley (20, 22) for a belt drive (16) is provided on the surface (27) of its circumference (28) at least partially with an increased roughness, the average roughness of the sections (30) which are provided with increased roughness, at least 1.2 microns.

Description

The invention relates to a pulley for a belt drive, a belt for a belt drive and a belt drive and a steering system with a belt drive. The invention further relates to a method for producing a pulley and a belt.

Belt drives are used, for example, in steering systems to reduce the steering forces. Such a belt drive has at least two pulleys and a belt which is stretched around the pulleys and these coupled together. One of the pulleys is driven, for example by a motor. The other pulley, which is coupled via the belt to the first pulley, is rotated over the belt with this. This pulley may be coupled to a steering actuator, so that the steering forces can be reduced by the engine.

The belt should be performed as quietly as possible on the pulleys. On the other hand, the belt should not slippage on the pulley to allow a direct power transmission. In order to prevent slippage of the belt drive, it is known from the prior art that on the belt and on the pulleys corresponding tooth profiles are provided or the tension of the belt is selected so high that the belt is pressed with a large pressing force against the pulley ,

In both cases, to reduce the wear of the belt drive, the surface of the pulley and the running surface of the belt as smooth as possible, that is carried out with a low roughness.

However, in conventional belt drives strong noise emissions occur. These are due to relative movements between belt and pulley in the micrometer range, so-called micro-sliding. The micro-gliding results in high-frequency vibrations of the belt causing sound waves in the audible range. As a result, the noise emission of the belt drive is greatly increased.

It is an object of the invention to provide a pulley, a belt and a belt drive and a steering system with such a belt drive, which have a low noise emission.

To solve the problem, a pulley is provided for a belt drive, wherein the circumference of the pulley is at least partially provided with increased roughness, wherein the average roughness of the sections, which are provided with increased roughness, is at least 1.2 microns. This increases the friction between the pulley and the belt, which prevents micro-gliding. The invention is based on the basic idea that relative movements between the belt pulley and the belt can be effectively prevented by increased friction between these parts, so that micro-gliding with a corresponding noise emission is suppressed or at least reduced.

Preferably, the portions provided with increased roughness have an average roughness in the range of 1.2 μm to 2.5 μm. At higher average roughness values, wear increases sharply, with lower average roughness levels increasing noise. Also, if the average roughness values are too high, the relatively moving surfaces of the belt and pulley become caught. If the belt surface is vibrated again when the entanglement is released by the elastic restoring force of the belt, the noise emission can increase again in this case, with high center roughness values. The range between 1.2 μm to 2.5 μm has proved to be the ideal compromise between noise and wear, as the wear also increases the increased friction between the belt pulley and the belt. In order not to unnecessarily limit the life of the belt drive so a compromise in the choice of roughness is indicated. In tests, a roughness with a center roughness in the order of 1.2 microns has proven to be an ideal compromise between low wear and the lowest possible operation of such a belt drive. In addition, this effect is independent of the macroscopic geometry of the pulley and can thus be applied to toothed and pulleys without special structure.

In such a pulley, it is also possible that this has at least partially a toothing over its circumference, can be reliably prevented by the slip between the pulley and belt drive. The toothing consists in particular of teeth formed transversely to the direction of rotation of the pulley. The sections with increased roughness can be provided on all surfaces of the toothing, such as tooth flank, head surface and / or tooth base.

The invention further relates to a belt for a belt drive. The running surface of the belt is at least partially provided with an increased roughness, wherein the average roughness of the Sections with increased roughness are at least 1.2 μm. In this way, the change in the roughness of the belt can be used to prevent micro-gliding and thus noise emissions.

Preferably, the portions provided with increased roughness have an average roughness in the range of 1.2 microns to 2.5 microns, since the range between 1.2 microns to 2.5 microns as the ideal compromise between noise and increased wear has exposed.

The belt may also be a toothed belt having teeth formed on the tread transversely to the running direction of the belt, whereby a slip-free belt drive can be realized.

According to the invention, a belt drive is furthermore provided, with at least one belt and at least two belt pulleys coupled by the one belt, wherein at least one of the belt pulleys and / or the belt is a pulley and / or belt according to the invention.

In one embodiment, when the belt is unrolled on one of the pulleys, the portions of increased belt and pulley roughness are in contact thereby further increasing the friction between the belt and pulley to more effectively prevent micro-gliding.

To solve the problem, a steering system is further provided with a steering actuator, a motor and a belt drive according to the invention, wherein the belt drive couples the engine with the steering actuator.

To solve the problem, a method for producing a belt pulley according to the invention and / or a belt according to the invention is further provided, wherein the pulley and / or the belt is provided on its circumference or its running surface at least partially with an increased roughness. The sections which are provided with increased roughness are preferably provided with a central roughness of at least 1.2 μm, in particular with a mean roughness value between 1.2 μm and 2.5 μm.

To increase the roughness, for example, a contacting method, in particular a blasting method, particularly preferably a sand blasting method is used with which a simple machining of the surface of the pulley and / or the belt is possible.

To increase the roughness may also be a non-contact method, such as laser polishing, which also allows easy machining of the surface of the pulley and / or the belt.

Further advantages and features will become apparent from the following description taken in conjunction with the accompanying drawings. In these show:

1 an inventive steering system;

2 the belt drive of the steering system according to the invention 1 ;

3 an inventive pulley of the belt drive from 2 ;

4 a further embodiment of the invention of the belt drive of the steering system 1 ; and

5 a pulley of the belt drive 4 ;

In 1 is a steering system 10 with a steering actuator 12 and a steering linkage 14 shown. Furthermore, a belt drive 16 provided a motor 18 , For example, an electric motor, with the steering linkage 14 coupled.

Upon actuation of the steering actuator 12 becomes the engine 18 activated, so over the belt drive 16 the steering linkage 14 is moved. This requires an operator to move the steering linkage 14 a significant low steering force on the steering actuator 12 or the steering linkage 14 be applied.

The motor 18 is with a first pulley 20 the belt drive 16 connected. A second pulley 22 is non-rotatable with the steering linkage 14 and thus with the steering actuator 12 coupled. To both pulleys 20 . 22 runs a prestressed belt 24 ,

Will the steering actuator 12 , for example via a steering wheel 26 , pressed, the engine becomes 18 activated, and can via the belt drive 16 a rotation or a movement of the steering linkage 14 support.

The belt drive 16 is in detail in 2 shown.

The first pulley 20 , the rotation with the engine 18 is coupled in the embodiment shown here has a smaller diameter than the second pulley 22 so the belt drive 16 acts as a reduction gear.

The belt 24 is designed as a toothed belt and has on its tread transverse to its direction of trained teeth. Accordingly, the pulleys 20 . 22 at its periphery 28 at least partially a gearing on. This toothing may be transverse to the direction of rotation of the pulley 20 . 22 trained teeth exist. The teeth of the pulleys mesh 20 . 22 with the teeth of the belt 24 so the belt 24 positive fit on the pulleys 20 . 22 attacks and slippage is reliably prevented.

The second pulley 22 is in detail in 3 shown, wherein belt sliding 20 the same surface topology as pulley 22 so that the same reference numerals for corresponding parts of the pulley 20 be used.

The second pulley 22 points to the surface 27 of the scope 28 sections 30 on, which have an increased roughness. These sections 30 are so on the entire circumference 28 the pulley 22 distributed that regardless of the rotational position of the second pulley 22 always at least one section 30 with the belt 24 the belt drive 16 is in contact.

The sections can 30 with increased roughness on all parts of the surfaces 27 the toothing, such as tooth flank, head surface and / or tooth base be provided.

Likewise, the belt points to its tread 25 sections 32 on, which have an increased roughness. These sections 32 can do so on the entire tread 25 of the belt 24 be spread out while unrolling the belt 24 on one of the pulleys 20 . 22 with the sections 30 with increased roughness of the pulleys 20 . 22 are in contact.

Through the sections 36 With increased roughness, the friction between belts becomes 24 and the pulleys 20 . 22 significantly increased, allowing a micro-sliding of the belt 24 on the pulleys 20 . 22 is reduced. This also reduces the vibrations of the belt 24 drastically, which in turn leads to a greatly reduced noise emission.

The mean roughness of the roughness of the sections 30 . 32 the surface 27 of the scope 28 the pulley 20 or the tread 25 of the belt 24 is at least 1.2 microns, with the average roughness should not exceed a value of 2.5 microns. In this area is an ideal compromise between the lowest possible friction, so low wear, between the belt 24 and the pulleys 20 . 22 and as quiet as possible operation of the belt drive 16 reached.

For a larger roughness, the belt would 24 much more difficult on the pulleys 20 . 22 unwind, which would lead to increased wear. On the other hand, with less roughness, the friction between pulleys would be 20 . 22 and straps 24 less, which would cause micro-gliding, causing belt vibrations 24 and eventually lead to noise emissions.

The increased roughness can be applied to the surface by any method known in the art 27 of the scope 28 the pulleys 20 . 22 and / or the tread 25 of the belt 24 be applied. In particular, contacting methods, for example blasting methods, such as sand blasting, or non-touching methods, such as laser polishing, are suitable. These methods have in common that with them a simple processing of the surfaces 27 or tread 25 is possible.

4 and 5 show an alternative embodiment of the belt drive or the pulley, the embodiment according to the 2 and 3 correspond. In the following, only the differences will be discussed and identical or functionally identical parts are provided with the previously introduced reference numerals.

In this embodiment, the pulleys 20 ' . 22 ' and the belt 24 ' at its periphery 28 ' or tread 25 ' no teeth on.

In addition, the belt points 24 ' no sections with increased roughness.

The sections 30 ' the pulleys 20 ' . 22 ' with increased roughness now extend over the entire surface 27 ' of the scope 28 ' the pulleys 20 ' . 22 ' allowing micro-gliding along the entire circumference of the pulleys 20 ' . 22 ' is prevented.

The features shown in this embodiment are of course also individually on the belt drive 16 , the pulleys 20 . 22 as well as the belt 24 transferable.

Claims (13)

Pulley for a belt drive ( 16 ; 16 ' ), characterized in that the surface ( 27 ; 27 ' ) of the scope ( 28 ; 28 ' ) is at least partially provided with an increased roughness, wherein the average roughness of the sections ( 30 ; 30 ' ), with increased roughness are provided, at least 1.2 microns. Pulley according to claim 1, characterized in that the sections ( 30 ; 30 ' ), which are provided with increased roughness, have an average roughness in the range of 1.2 microns to 2.5 microns. Pulley according to one of the preceding claims, characterized in that the pulley at its periphery at least partially has a toothing, in particular from transversely to the direction of rotation of the pulley ( 20 . 22 ; 20 ' . 22 ' ) formed teeth. Belt for a belt drive ( 16 ; 16 ' ), characterized in that the tread ( 25 ; 25 ' ) of the belt ( 24 ; 24 ' ) is at least partially provided with an increased roughness, wherein the average roughness of the sections ( 32 ), which are provided with increased roughness, is at least 1.2 microns. Belt according to claim 4, characterized in that the sections ( 32 ), which are provided with increased roughness, have an average roughness in the range of 1.2 microns to 2.5 microns. Belt drive according to claim 4 or 5, characterized in that the belt ( 24 ; 24 ' ) is a toothed belt, which at the tread ( 25 ; 25 ' ) has teeth formed transversely to the running direction of the belt. Belt drive ( 16 ; 16 ' ), in particular for a steering system, with at least one belt ( 24 ; 24 ' ) and at least two by the at least one belt ( 24 ; 24 ' ) coupled pulleys ( 20 . 22 ; 20 ' . 22 ' ), wherein at least one of the pulleys ( 20 . 22 ; 20 ' . 22 ' ) on the surface ( 27 ; 27 ' ) of the scope ( 28 ; 28 ' ) and / or the belt ( 24 ; 24 ' ) on the tread ( 25 ; 25 ' ) has at least partially sections which are provided with an increased roughness, the average roughness of the sections ( 30 . 32 ; 30 ' ), which are provided with increased roughness, is at least 1.2 microns. Belt drive according to claim 7, characterized in that the sections ( 30 . 32 ; 30 ' ) with increased roughness of belts ( 24 ; 24 ' ) and pulley ( 20 . 22 ; 20 ' . 22 ' ) when unrolling the belt ( 24 ; 24 ' ) on one of the pulleys ( 20 . 22 ; 20 ' . 22 ' ) are in contact. Belt drive according to claim 7 or 8, characterized in that the belt ( 24 ; 24 ' ) in the pulley ( 20 . 22 ; 20 ' . 22 ' ) attacks. Steering system ( 10 ) with a steering actuator ( 12 ), a motor ( 18 ) and a belt drive ( 16 ; 16 ' ) according to one of claims 7 to 9, characterized in that the belt drive ( 16 ; 16 ' ) the engine ( 18 ) with the steering actuator ( 12 ) couples. Method for producing a pulley ( 20 . 22 ; 20 ' . 22 ' ) and / or a belt ( 24 ; 24 ' ) for a belt drive ( 16 ; 16 ' ), characterized by a method step in which the pulley ( 20 . 22 ; 20 ' . 22 ' ) and / or the belt ( 24 ; 24 ' ) is provided, at least in sections, with an increased roughness, in particular with a mean roughness of at least 1.2 μm, in particular between 1.2 and 2.5 μm. A method according to claim 11, characterized in that the method is a contacting method, in particular a blasting method, particularly preferably a sandblasting method. A method according to claim 11, characterized in that the method is a non-contacting method, in particular laser polishing.

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