DE102009000795A1 - Clamping element for drive unit pinion of internal combustion engine for motor vehicle, has clamping surface attached at drive unit in neutral position, and segments of needle bearing arranged directly at clamping surface - Google Patents

Abstract

The element (6) has a inner surface (12) oriented towards a drive unit (4), where the element is rotatably supported around an rotational axle (11), which is arranged within a clamping element body. The inner surface comprises a clamping surface (13) that is convexly curved with respect to the rotation axle. The clamping surface is attached at the drive unit in a neutral position. Segments (23) e.g. roller bearings, of needle bearing are arranged directly at the clamping surface or arranged directly at a separate carrier element.

Description

The The invention relates to a clamping element for a drive means drive wherein the tensioning element about an axis of rotation, within the clamping element body is arranged pivotally mounted, and wherein the clamping element has an inner surface oriented toward the drive means, which has a clamping surface, based on the axis of rotation is convex and at least partially in a neutral position abuts the drive means.

such Clamping elements are z. B. for propulsion systems known. One exemplary drive system has a drive wheel and at least a driven wheel, via the drive means with each other are connected, wherein the drive means associated with a clamping system is that at least that clamping element has, for example with the drive system ancillaries such. B. the oil pump powered by a hydraulically assisted power steering be by the rotation of the crankshaft associated drive wheel by means of the drive means on the associated with the accessory Output gear is transmitted to the exemplary oil pump drive. But also known is the drive system for the primary drive of the internal combustion engine (crankshaft / camshaft) to use. But are also known systems in which an electric motor via a drive means (eg toothed belt) drives a ball screw (belt-driven electric power steering).

When Drive means are usually endless chains running or belt or toothed belt used. In particular, the drive means should preferably operated with low maintenance by retightening become; because the drive means is subject during his Operation of a continuous change in length. Often this clamping systems are used to the drive means to keep under tension, and thus a safe as possible and wear-free drive.

When a major drawback of the clamping systems is that these are very elaborately constructed and thus are themselves very maintenance-intensive, so that the advantage of the low-maintenance drive system virtually eliminated is. The complex construction results from the variety of components from which the clamping system is constructed.

The DE 10 2006 058 960 A1 discloses a traction drive for an internal combustion engine with a trained as a belt traction means which connects a driven wheel with a drive wheel. The traction means is exposed to an oil mist or at least partially immersed in an oil bath. The traction mechanism drive has a belt-biasing clamping rail, which is supported by means of at least one rotatably mounted guide roller on the traction means. The guide roller has a plain bearing. The tensioning rail consists of two axially spaced flat profiles, which are interconnected by connecting webs. Between the flat profiles guide rollers are rotatably mounted on bolts. The belt is disposed between the spaced flat profiles and is deflected by the guide roller (s).

in principle are toothed drive belts or untoothed drive belts as Drive means advantageously in motor vehicles or internal combustion engines used. In particular, an increasing application is more intermeshed Belts, which can also be called synchronous belts, or To observe belts in wet, ie in oily environment. Here, the drive system is housed in a housing, gets into the lubricant or oil. Usually is the drive wheel associated with the crankshaft gear or Disk wheel, which rotates in an oil bath. These "wet" timing belts or belts, for example, in primary drives, but also for driving ancillaries such. B. of oil pumps used for hydraulic power steering. At the primary drives are Relatively expensive designed and costly clamping systems used to tension the timing belt or belt. To drive of ancillaries are currently no reasons of cost Clamping systems as used in the primary drives. Indeed shows a "wet" toothed belt drive or belt drive without clamping system significantly reduced dynamic properties z. B. in the transmission of torque from the drive wheel the output gear, resulting in a very short life of the belt or belt results. It is known in the accessory drive costly tensioners to use. For cost reasons, should on the tensioner solution be waived, which by means of the use of highly elastic belts should be achieved. However, the use of highly elastic straps is for the sake of a very elaborate assembly and due the problem in the control of rotational vibrations disadvantageous.

Another disadvantage is the fact that the slide rails require a relatively high bias, which is required to control the drive means or the timing belt or belt with respect to its adjustment and movement in the entire speed range of the internal combustion engine. The bias may be applied by spring elements, hydraulic components or other suitable devices. An advantage of a "wet" timing belt is to be seen in an expected lower drive friction, this advantage being offset by the relatively high preload. As a "worst case" of a drive system or Be It is to be regarded as a failure of a drive system that the drive means or the toothed belt or belt deflects under certain conditions or, in the case of the toothed belt, moves out of the toothed wheel recesses in certain areas. This causes spur and control losses in the drive system.

at a drive system of the type mentioned, the drive means for example, in the embodiment as a toothed belt or belt means the clamping element tensioned by the clamping element in its neutral Position with its clamping surface on one to the inside opposite rear side of the drive means at least partially applied. The tensioning element is about its axis of rotation rotatably mounted around. To tighten the drive means is the Tensioning element pivoted out of its neutral position, and steers with its clamping surface while the drive means or the corresponding strand in the direction of the other strand. This is favorable when the clamping surface based is convex on the axis of rotation, so based on the axis of rotation is oriented away from this arched.

in principle This principle has proven itself in practice. Indeed lies between the clamping surface of the clamping element and the Rear of the drive means or the belt or the Timing belt a relative movement, ie a sliding movement before. These Sliding motion results in high coefficients of friction, especially at low levels Speeds. Here, the oil film may be too thin for be a dynamic friction. The increased friction works detrimental to the life of the drive means.

From Therefore, the invention has the object, a clamping element to improve the input type with simple means so that the coefficients of friction between the clamping surface and the back the drive means are reduced even at low speeds.

According to the invention the object by a drive system with the features of the claim 1 solved, wherein the clamping element on its clamping surface Having segments of needle bearings. The mentioned segments are preferred designed as a rolling element of a needle bearing.

Cheap in the context of the invention is when the segments or the rolling elements of the needle bearing by means of a similar to the connection the rolling elements with a needle roller cage suitable clip connection with the clamping surface or edge areas be connected by it, so that the rolling elements survive a little over the clamping surface and can rotate around its axis of rotation.

In expedient embodiment, the segments of Needle bearing or its rolling elements on a separate Support element arranged which frictionally with may be connected to the clamping element, wherein the separate support element advantageous in the manner of a clip connection with the clamping element can be connected. It is advantageous if the support element engages around side edges of the clamping element with suitable locking means this engages behind and is thus locked with the clamping element. Naturally can also connect other suitable types of connection the separate support element, which has the needle bearing, with provided with the clamping element or with its inner surface be.

Cheap within the meaning of the invention, if the segments of the needle roller bearings, too if they are arranged on the separate support element, preferred to each other have a constant distance. The distance between adjacent ones Segments of the needle roller bearings should preferably be chosen so that a contact of the belt or belt with between the segments the needle bearing arranged spaces largely or entirely is avoided.

The Clamping element has the inner surface oriented toward the drive means on which the clamping surface and a stop surface having. The clamping surface merges into the stop surface. The toothed belt or belt can hit the stop surface, if it fails under certain conditions or, in case a toothed belt, in certain areas out of the gear wells could. This affects a tooth jumping and control losses in the drive system. Cheaper way is the Stop surface therefore quasi rectilinear, so that between the stop surface and the drive means A gap is formed, extending from the transition of the clamping surface to the abutment surface towards one end of the abutment surface preferably steadily expanded.

In expedient embodiment is provided that the support element to the configuration of the inner surface Corresponding to this is adapted, so one to the clamping surface and corresponding to the stop surface Has history, the segments of the needle roller bearing preferably only be arranged in the area of the clamping surface, since the clamping element rests only here on the drive means.

The clamping element is designed as a finger tensioner whose clamping element body has a recess in the manner of a bearing eye into which a pivot pin of a fastening element engages, so that the clamping element about the pivot pin, which forms the axis of rotation, pivot bar is. In order to pivot the clamping element, suitable active devices can act on the clamping element. The axis of rotation is arranged in an expedient embodiment based on the clamping surface above this, wherein the suitable active device acts on the clamping element with respect to the axis of rotation below it.

All in all With the invention, an improved clamping element is available provided in which the relative movement between the clamping element or its clamping surface and the drive means or the toothed belt is a rolling motion, with a sliding movement is avoided. This is advantageous by means of arranged on the clamping surface segments reached by needle bearings (rolling elements), which with its axis of rotation of course so to the direction the drive means are arranged, that these due to the running movement of the drive means rotate. In this respect, the advantage is the friction between the drive means and the clamping element or its clamping surface reduced. It is advantageous that even at a low Speed an increased friction coefficient is avoided. For reasons of space But no deflection roller or tension roller can be used. Much more For these reasons, the clamping element of the input mentioned type in the manner of a finger tensioning element, which also as Spannschuh can be called used.

Further advantageous embodiments of the invention are in the subclaims and the following description of the figures. Show it

1 a drive system in a perspective view,

2 a section from 1 , and

3 a clamping element as a detail in a perspective view.

In the different figures are the same parts always with them Reference numerals provided, which is why these usually described only once become.

1 shows a drive system 1 , The drive system 1 has a drive wheel 2 and a driven wheel 3 on that, via a drive means 4 connected to each other. The drive means 4 is a tensioning element 6 assigned.

In the illustrated embodiment, the drive wheel 2 as a, a crankshaft of an internal combustion engine associated wheel, or crankshaft gear executed. The driven wheel 3 is designed as a, an accessory, such as an oil pump hydraulic power steering motor vehicle associated gear, or oil pump gear. The drive means 4 is as a timing belt 4 with a tooth side 7 and an opposite outside or back 8th executed. The teeth of the tooth side 7 are not shown. Of course, a non-toothed belt can be used, so that it has no tooth side but an inside. The driven wheel 3 drives a balance shaft wheel 9 at.

The drive system 1 can be housed in a housing, not shown, so that even from a "wet" or "oily" drive system 1 can be spoken.

The tensioning element 6 is about a rotation axis 11 pivoted ( 2 ). The rotation axis 11 is disposed within the tension member body. The tensioning element 6 further includes a drive means 4 oriented inner surface 12 on top of that, a clamping surface 13 and a stop surface 14 Has. The clamping surface 13 is related to the axis of rotation 11 convex arched. The clamping surface 13 goes into the stop area 14 above. The stop surface 14 is exemplified running straight, so that a gap 16 between the stop surface 14 and the back 8th of the drive means 4 starting at the transition from the clamping surface 13 to the stop surface 14 towards an end 17 the stop surface 14 extended, preferably steadily expanded.

The rotation axis 11 is from a pintle 18 formed in a recess 19 , which may also be referred to as a bearing eye, and which is arranged in the clamping element body, engages. The pintle 18 is on a fastener 21 arranged.

With the clamping surface 13 is the clamping element 6 on the drive means 4 or its back 8th in the illustrated neutral position in some areas and directs the drive means 4 or the corresponding strand in the direction of the other strand ( 2 ).

On the inner surface 12 is a separate support element 22 arranged ( 3 ). The support element 22 has a to the course of the inner surface 12 or their clamping surface 13 and stop surface 14 adapted design. In this respect, the support element 22 in accordance with the previously described also to the drive means 4 oriented clamping surface 13 and stop surface 14 why they have the same reference numerals. The support element 22 is connected with suitable latching means with the clamping element body sufficiently secure position. As exemplified ( 3 ) extends the separate support element 22 with his to the stop surface 14 fitted section up just before the end 17 , so that here a step is formed.

At the clamping surface 13 are segments 23 arranged by needle bearings ( 3 ). The segments are preferred 23 designed as a rolling element of a needle bearing. As exemplified are several segments 23 provided by needle bearings, each having an equal distance from each other. The segments 23 or rolling elements are arranged with their axis of rotation so that the acting running movement of the drive means 4 a rotation of the segments 23 or the rolling element causes. To enable a rotational movement are the segments 23 similar to the connection in needle roller cages with the separate support element 22 connected. In a favorable embodiment, it is provided that the segments 23 or rolling elements to the width of a supporting element 22 have adapted axial length. Thus, the relative movement between the drive means is advantageous 4 and the tensioning element 6 or the clamping surface 13 a rolling motion. For a sliding movement is advantageously avoided as a relative movement.

The distances between adjacent segments 23 or rolling elements are preferably selected so that a contact of the back 8th of the drive means 4 with between the needle bearings 23 arranged spaces 24 is avoided.

The advantage is that with the segments 23 provided by needle bearings separate support element 22 due to the rotating segments 23 or the rotating rolling element, the friction between the drive means 4 and the tensioning element 6 reduced or preferably completely avoided even at low speeds. It is perfectly within the meaning of the invention that the segments 23 directly at the clamping surface 13 of the clamping element 6 could be mounted without a separate support element would be used.

Advantageous is the separate support element 22 with the segments arranged thereon 23 of needle bearings not only as standard on the clamping element 6 mountable but also retrofittable to existing clamping elements mountable. Of course, the support element 22 with segments arranged thereon 23 from needle bearings also only to the clamping surface 13 be executed adapted, which could be dispensed with a previously described adapted to the stop surface portion.

The segments 23 Needle bearings can, as already described, either directly on the clamping surface 13 or on the separate support element 22 be arranged. In this respect, either the clamping surface 13 with the segments arranged directly on it 23 or rolling elements or the support element 22 in the corresponding area (clamping surface 13 of the support element 22 ) Also in the manner of a needle roller cage with appropriate receptacles for the respective segments 23 or rolling elements be executed.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102006058960 A1 [0005]

Claims (6)

Clamping element for a drive means drive wherein the tensioning element ( 6 ) about a rotation axis ( 11 ), which is arranged within the clamping element body, is pivotally mounted, and wherein the clamping element ( 6 ) one to the drive means ( 4 ) oriented inner surface ( 12 ) having a clamping surface ( 13 ), which relative to the axis of rotation ( 11 ) is curved convexly and at least partially in a neutral position on the drive means ( 4 ) is applied, characterized in that on the clamping surface ( 13 ) Segments ( 23 ) are arranged by needle bearings. Clamping element according to claim 1, characterized in that the segments ( 23 ) on a separate support element ( 22 ) or directly on the clamping surface ( 13 ) are arranged. Clamping element according to claim 2, characterized in that the support element ( 22 ) positively locking with the clamping element ( 6 ) is connectable. Clamping element according to one of the preceding claims, characterized in that respectively adjacent segments ( 23 ) on the clamping surface ( 13 ) have an equal distance from each other. Clamping element according to one of claims 2 to 4, characterized in that the support element ( 22 ) to the design of the inner surface ( 12 ) is executed adapted. Clamping element according to one of the preceding claims, characterized in that the segments ( 23 ) are executed by needle bearings as rolling elements.