WO2008061855A1 - Tensioning device of a traction mechanism drive - Google Patents

Abstract

A tensioning device of a traction mechanism drive with a tensioning lever (2) which is rotatably mounted via a pivot bearing (3) on a base housing (4) such that said tensioning lever is provided with a rotatable tension roller (33) at a radial distance from the rotational axis (5) of the pivot bearing (3). Said tensioning lever is arranged coaxially to the pivot bearing (3) by means of [ ] designed as a legless coil spring (15). For the improvement of the balancing of the pivot bearing and the adjustability of the frictional damping of the tensioning lever, the spring end (16) of the torsion spring (14) on the lever side is connected to the tensioning lever (2) via a wedge element (20) and a driver (21) attached to the tensioning lever (2), wherein the wedge element (20) lies on the spring end (16) of the coil spring (15) on the lever side with a pressure surface (22) oriented radially around an axis, and said wedge element (20) lies on an identically inclined wedge surface (24) of the driver (21) with a wedge surface (23) inclined away from the spring end (16) on the lever side on the outer radius, and said wedge element (20) lies on a cylindrical inner wall (26) of the base housing (4) with a frictional surface (25) on the outside of a cylinder.

Description

 Name of the invention

Clamping device of a traction mechanism drive

Field of the invention

The invention relates to a tensioning device of a traction mechanism drive, with a rotatably mounted on a base housing via a pivot bearing and radially spaced from the axis of rotation of the pivot bearing provided with a rotatable tension roller clamping lever, which is arranged by means of a thighless helical spring, coaxial with the pivot bearing and at the spring ends a pivotable about the axis of rotation of the pivot bearing, wherein the pivot bearing is formed by a bearing pin, a bearing hub and at least one arranged between the bearing pin and the bearing hub plain bearing bush, and wherein a middle radial force application plane of the tension roller is axially spaced from a central radial bearing plane of the pivot bearing.

Background of the invention

Clamping devices with a plain bearing designed as a plain bearing, designed as a helical spring torsion spring and an axially spaced-apart arrangement of the tensioning roller and the pivot bearing come in different embodiments, preferably in ancillary trains of internal combustion engines for use. Such tensioning devices are both in an internally mounted embodiment with a bearing of the rigidly connected to the clamping lever bearing pin in the forming a part of the base housing bearing hub and in an externally mounted design with a storage of rigidly connected to the clamping lever bearing hub on the one part of the base housing forming bearing pin known. In this case, the base housing is provided in each case for fastening the respective clamping device to a motor housing, such as the crankcase or the control housing of a combustion piston engine.

With regard to the arrangement of the tensioning roller can in such a clamping device in addition between a so-called offset or Z-type, in which the tension roller is arranged axially on the side facing away from the base housing outside of the clamping lever, and a so-called inline or U-type , in which the tension roller is arranged radially laterally of the base housing axially on the inner side facing the base housing of the clamping lever, a distinction can be made.

The pivot bearing, by which the radial bearing of the clamping lever is accomplished in or on the base housing, has at least one plain bearing bush, which is arranged between the bearing hub and the bearing pin and usually consists of a durable and at the same time low-friction plastic material. The plain bearing bush and the inner bearing wall of the bearing hub and the outer bearing wall of the bearing bolt which are in contact therewith may be cylindrical or conical in a known manner, with an additional thrust bearing, e.g. in the form of a slide bearing disc arranged between a housing-fixed and a lever-fixed bearing plate, whereas a cone-cylindrical pivot bearing in conjunction with an axial prestressing of the torsion spring includes the axial bearing of the tensioning lever.

Regardless of the geometric structure of the pivot bearing acts on the at least one plain bearing bush, a resulting radial force resulting from the force acting on the clamping lever spring force of the torsion spring and exerted by the traction means on the tensioning roller on the tensioning lever reaction force. However, since at least one of the radial planes in which the spring force acting on the tensioning lever by means of the torsion spring and the reaction force of the traction means, usually axially spaced from a central radial bearing plane of the pivot bearing and the plain bearing bushing of the pivot bearing, inevitably results in a resulting tilting moment about a tilt axis perpendicular to the axis of rotation of the pivot bearing in the middle storage level lies.

This tilting moment disadvantageously causes a non-uniform, so axial end side diagonally opposite, one-sided load the Schwenkla- gers with a high local pressure and edge load of the plain bearing bush, which leads to uneven wear of the plain bearing bush and consequently to undesirable misalignment of the clamping lever and the this fixed tensioning roller with respect to the traction means leads.

In order to achieve the most complete possible balancing of the pivot bearing and thus a tilting torque-free and thus uniform loading of the plain bearing bush and at the same time an effective friction damping of a pivoting movement of the tension lever and thus a vibration of the traction means running on the tension pulley, is in the unpublished patent application DE 102 006 014 942.4 the Applicant has already been proposed a novel clamping device in which the torsion spring is designed as a load-bearing in the open sense legless coil spring. The lever-side spring end of the torsion spring abuts against an axially-radially aligned abutment surface of a lever-fixed driver. The driver is with respect to the rotational axis of the pivot bearing circumferentially arranged such that the stop surface is aligned normal to a resultant reaction force of a traction means on the tension roller. The support of a reaction force of the clamping lever on the coil spring takes place relative to the base housing. The middle of the lever-side spring end is axially spaced apart from the middle bearing plane of the pivot bearing in such a way that the tilting moments of the tangential spring force of the coil spring and that via the tensioning roller effectively cancel each other on the tensioning lever resulting reaction force of the traction means.

The support of the reaction force of the clamping lever on the coil spring is preferably carried out via a sliding block which is arranged offset back about the axis of rotation of the pivot bearing on the outer lever-side turn of the coil spring from the stop surface of the driver by about 90 °, radially inwardly on the outer lever-side turn of Coil spring rests, is guided in a radial guide of the clamping lever radially movable, and rests radially on the outside with a friction surface on a cylindrical inner wall of the base housing. This results in a high spring force proportional and thus dependent on the current position of the clamping lever friction damping of the pivotal movement of the clamping lever.

Another friction torque for damping a pivoting movement of the tensioning lever and a further lever force for balancing the pivot bearing can be achieved by a corresponding arrangement of a second sliding shoe on the outer housing-side turn of the coil spring. The local reaction force of the base housing on the coil spring is effective both as radia- Ie contact force of the shoe against a cylindrical inner wall of the clamping lever and as a balancing leverage around the tilting axis of the plain bearing bushing of the pivot bearing.

Despite the advantages of the clamping device known from DE 102 006 014 942.4, the existing possibilities may not be sufficient in certain applications or, for example due to confined space at the installation site, not be used or optimally utilized in order to achieve a complete balance of the pivot bearing and / or. or to achieve the setting of a desired damping behavior of the tensioning device. Object of the invention

It is therefore the object of the present invention to further develop the clamping device known from DE 102 006 014 942.4 with regard to alternative and / or supplementary possibilities for balancing the pivot bearing and for adjusting the friction damping of the tension lever.

Summary of the invention

The invention is based on the finding that a friction torque for friction damping of a pivoting movement of the clamping lever can also be generated by a support of the lever-side tangential spring force F _F _τ of the torsion spring against the lever-fixed driver via a wedge element. In this case, a radial contact force F _{KR is} generated by a support of the wedge element on the driver on both sides wedge surfaces, pressed with the wedge member radially outward with an outer cylindrical friction surface against a cylindrical inner wall of the base housing and thus during a pivoting movement of the clamping lever due to the tangential relative movement between the Wedge element and the base housing a friction torque is generated.

The invention therefore relates to a tensioning device of a traction mechanism drive, with a rotatably mounted on a base housing via a pivot bearing and radially spaced from the axis of rotation of the pivot bearing provided with a rotatable tension roller clamping lever, which is arranged by means of a thighless helical spring, coaxial with the pivot bearing and to the spring ends on the casing side to the base housing as well as the lever side with the clamping lever in operative connection torsion spring having a torsional moment M _τ to the axis of rotation of the pivot bearing can be acted upon, wherein the pivot bearing is arranged by a bearing bolt, a bearing hub and at least one between the bearing pin and the bearing hub Plain bearing bush is formed, and wherein a mean radial force application plane of the tension roller is axially spaced from a central radial bearing plane of the pivot bearing. According to the invention, it is additionally provided that the torsion-side spring end of the torsion spring is connected to the tensioning lever via a wedge element and a lever-fixed catch, wherein the wedge element bears against the lever-side spring end of the coil spring with an axially-radially aligned pressure surface radially outwardly of the lever-side spring end inclined wedge surface rests against an equally inclined wedge surface of the driver, and with an outer cylindrical Reibflä- che rests against a cylindrical inner wall of the base housing.

The wedge element causes the lever-side tangential spring force F _F _τ of the torsion spring, whose height increases or decreases in proportion to the actual torsional moment between the tensioning lever and the base housing, to be dependent on the inclination of the wedge surfaces of the wedge element and the carrier in accordance with the vectorial equilibrium of forces the wedge element in a normal standing on the wedge surface of the wedge element supporting force F _KN and converted into a radial contact force F _KR . While the supporting force F _{KN is introduced} via the wedge surface of the driver in the clamping lever and is used to balance the at least one plain bearing bushing of the pivot bearing, the wedge member is pressed by the radial contact force F _KR with its outer cylindrical friction surface against the cylindrical inner wall of the base housing, creating a Friction torque for friction damping of a pivoting movement of the clamping lever is generated about the axis of rotation of the pivot bearing.

The angle of inclination of the two wedge surfaces serves as an adjustment parameter for adjusting the height and direction of the support force F _KN and the height of the radial contact force F _KR . The wedge element also has the positive side effect that due to the tangential frictional force F _RT between the wedge element and the clamping lever, the radial contact pressure F _KR and thus the effective friction torque at a compression of the tensioning lever with respect to the torsion spring, which corresponds to a pivoting of the tensioning roller away from the traction means, additionally increased and at a rebound of the tensioning lever with respect to the torsion spring, which corresponds to a pivoting of the tensioning roller to the traction means out, is additionally reduced.

This effect is quite desirable because an outward swinging of the traction means is additionally inhibited due to the increased frictional damping of the tensioning lever, and the tensioning roller is tracked substantially delay-free due to the reduced frictional damping of the tensioning lever when the traction means oscillates inward. With the use of the wedge element is thus a simple and space-saving possibility of further adjustment of the balance of the pivot bearing and an additional or alternative friction damping of the clamping lever available.

Advantageous embodiments and further developments of the clamping device according to the invention are specified in claims 2 to 20.

The driver is preferably arranged circumferentially with respect to the axis of rotation of the pivot bearing such that the wedge surfaces of the wedge element and the driver are largely normal, that is perpendicular, aligned to a resultant reaction force F _Z _ _{R of} a traction device on the tension roller, as a result, a direct compensation of the overturning moment the reaction force F _{ZR of} the traction means on the tensioning roller about the tilting axis of the pivot bearing by the overturning moment of the supporting force F _KN on the driver and thus a uniform load on the plain bearing bushing of the pivot bearing is possible.

The angle of inclination of the wedge surfaces of the wedge element and the driver relative to the pressure surface of the wedge element, via which the height and direction of the used for balancing the pivot bearing support force F _KN and the amount of the radial contact force F _KR and thus of the friction torque used for the friction damping of the tensioning lever is adjustable relative to the tangential spring force F _F _τ of the torsion spring is suitably in a range between 30 ° and 60 °.

To achieve a desired, certain by the height of the radial pressing force F _κ N of the wedge element on the cylindrical inner wall of the base housing, and by the coefficient of friction between the outer cylindrical friction surface of the wedge member and the cylindrical inner wall of the base housing th damping behavior, the friction surface of the wedge element and / can or the cylindrical inner wall of the base housing may be provided with a friction lining. However, it is also possible that the entire wedge element consists of a resistant and friction-resistant plastic, which is in frictional contact directly with its outer cylindrical friction surface with the cylindrical inner wall of the base housing provided with or without friction lining.

To reduce the number of components and to simplify the assembly of the clamping device, the wedge member is advantageously integrally connected to an open bearing ring which is disposed between the outer lever-side turn of the coil spring and the clamping lever, which is spaced from the wedge element against the clamping lever positively secured against rotation , and which is fully opened immediately adjacent to the wedge surface of the wedge element. In this embodiment, sufficient mobility of the wedge element in the circumferential direction as well as in the radial direction is ensured by the opening of the bearing ring and its positive fastening away from the wedge element.

In order to achieve this space-saving design, the wedge element can advantageously protrude at least partially axially outside of the bearing ring and engage in a provided with the lever-side wedge surface radial groove of the clamping lever. The radial groove of the clamping lever can be provided on both sides in the circumferential direction with a wedge surface, as a result an identical clamping lever can be used both for a clamping device with clockwise clamping lever and for a clamping device with anti-clockwise clamping lever.

In a particularly advantageous embodiment of the tensioning device according to the invention, the wedge element and the driver are integrally connected to a slotted bearing ring, the düng between the outer lever side Win- the coil spring and the clamping lever is arranged, the close to the driver against the clamping lever form-fitting against rotation and against a radial displacement is secured, and which is provided between the wedge surface of the wedge element and the wedge surface of the driver with a separating slot. In this way, the application-specific design features, such as the circumferential orientation and the angle of inclination of the wedge surfaces of the wedge element and the driver, combined in the bearing ring, wherein the positive fixation of the bearing ring on the clamping lever, the functional fixation of the driver and the separating slot relative mobility of the wedge element with respect to the keN surface of the driver is ensured.

The positive connection of the bearing ring with the clamping lever can be suitably formed by a respective axial bore and a bolt inserted into the axial bores. The adaptation of the circumferential position and the direction of rotation of the clamping lever to the respective application can be done in a simple manner by the positioning of the lever-side axial bore in a standardized clamping lever.

Alternatively, the positive connection of the bearing ring with the clamping lever by an axially aligned inner radial groove of the bearing ring and engaging in this, axially extending outer radial web be formed of the clamping lever, since a load of the driver by the supporting force F _KN on the relevant wedge surface occurs only in the circumferential direction and radially inward. Due to the positioning of the radial web, however, the clamping lever in this case represents an application-specific component.

Analogous to the lever-side spring end of the torsion spring, the housing-side spring end of the torsion spring can also be connected to the base housing via a wedge element and a housing-mounted driver, the wedge element abutting against the housing-side spring end of the helical spring with an axially-radially aligned pressure surface radially outwardly of the housing side spring end inclined wedge surface rests against an equally inclined wedge surface of the driver, and rests with an outer cylindrical friction surface on a cylindrical inner wall of the clamping lever. Since in this case the radial contact force F _{KR of} the wedge element is effective on the clamping lever, on the housing side by the radial contact force F _K _R not only a frictional torque about the axis of rotation of the pivot bearing but also a usable for balancing the pivot bearing tilting moment about one in the middle bearing plane the slide bearing lying tilting axis generated.

In order to achieve in conjunction with the lever-side radial contact force F _{KR of} the wedge element on the clamping lever residual torque-free compensation of the tilting torque of the reaction force F _Z _ _{R of} the traction means on the tensioning roller about the tilting axis of the pivot bearing and thus a uniform load of the plain bearing bushing of the pivot bearing is housing-fixed driver expediently arranged circumferentially with respect to the axis of rotation of the pivot bearing such that an imaginary, the radial contact force F _{KR of} the wedge element containing radial surface is aligned substantially parallel to the resulting reaction force F _Z _ _{R of} the traction means on the tensioning roller. The further design features given above for the lever-side spring end of the torsion spring or the lever-side region of the tensioning device are also applicable to the housing-side spring end of the torsion spring or the housing-side region of the tensioning device, taking into account a construction-related permutation of tensioning lever and base housing.

As is known in principle from DE 102 006 014 942.4, the lever-side support of the reaction force F _F _ _{R of} the clamping lever on the coil spring for generating a further frictional torque via a sliding shoe, which is about the axis of rotation of the pivot bearing from the lever-side spring end is arranged offset by about 90 °, radially inwardly abuts the outer lever-side turn of the coil spring, is guided radially movable in a radial guide of the clamping lever, and rests with an outer cylindrical friction surface on a cylindrical inner wall of the base housing.

In this case, an increasingly rotationally dependent friction torque can be achieved, that the sliding shoe and the radial guide circumferentially on the side facing the lever side spring end each have a radially outwardly inclined to the lever side spring end wedge surface. Due to the wedge surfaces of the sliding shoe is additionally pressed with a compression of the clamping lever with respect to the torsion spring radially outward and thus increases the frictional torque generated by the reaction force F _FR .

Likewise, the housing-side support of the reaction force F _{FR of} the base housing can take place on the coil spring via a sliding shoe, which is arranged offset from the housing side spring end about 90 ° about the axis of rotation of the pivot bearing, rests radially inwardly on the outer housing side winding of the coil spring is guided radially movable in a radial guide of the base housing, and with an outer cylindrical Friction surface bears against a cylindrical inner wall of the clamping lever, wherein the sliding shoe and the radial guide circumferentially on the side facing the housing side spring end each have a radially outwardly inclined to the housing side spring end wedge surface.

In both Gleitschuhanordnungen the angle of inclination of the wedge surfaces of the shoe and the radial guide relative to an imaginary, the axis of rotation of the pivot bearing and the outer cylindrical friction surface of the shoe in approximately halving radial plane over which the rotational direction-dependent gain of the friction torque is adjustable, each preferably in a range between 30 ° and 60 °.

With sufficient flexibility of the respective bearing ring of the shoe can be integrally connected to the respective bearing ring, whereby the number of components is reduced and the assembly of the clamping device is facilitated.

In case of a housing-side use of a wedge element and a sliding shoe, which are both pressed against a cylindrical inner wall of the clamping lever, the resultant force vector from the radial contact force F _{KR of} the wedge element and effective as a radial contact force of the sliding shoe reaction force should F to the fullest possible balancing of the pivot bearing _{FR should be} aligned largely parallel to the resulting reaction force F _{ZR of} the traction device on the tension roller.

As an alternative to the use of a sliding shoe, the lever-side support of the reaction force F _{FR of} the clamping lever on the coil spring via a direct contact of a about the axis of rotation of the pivot bearing of the lever-side spring end of about 90 ° back portion of the outer lever-side turn of the coil spring with a cylindrical Inner wall of the base housing carried, wherein at least the outer lever-side winding of the coil spring and / or the cylindrical inner wall of the base housing is provided with a friction coating.

In the same way, the housing-side support of the reaction force F _{FR of} the base housing on the coil spring via a direct contact of about the axis of rotation of the pivot bearing of the housing-side spring end of about 90 ° back portion of the outer housing side turn of the coil spring a cylindrical inner wall of the clamping lever, wherein at least the outer housing side winding of the coil spring and / or the cylindrical inner wall of the clamping lever is also provided with a friction coating.

In the case of direct frictional contact of the outer turn of the helical spring with the base housing and / or the tension lever, the helical spring can advantageously be completely provided with a friction coating. This friction coating also acts as corrosion protection, so that an otherwise required corrosion protection treatment of the coil spring can be omitted.

Finally, it should be noted that the above-described embodiments, such as the use of a lever-side wedge element, a housing-side wedge element, a lever-side shoe with a wedge surface, a housing-side shoe with a wedge surface and a direct lever side and / or housing side frictional contact of the coil spring with the Base housing or with the clamping lever arbitrarily miteinan- combined and at least partially applicable to other types of clamping devices.

Brief description of the drawings

The invention will be explained in more detail with reference to the accompanying drawings of some embodiments. It shows 1 shows a preferred embodiment of the clamping device according to the invention in a perspective exploded view,

2 is an enlarged detail of Fig. 1,

3 shows an axial view of a bearing ring of the tensioning device according to FIG. 1 and FIG. 2 with an axially outward looking direction, FIG.

4a shows the forces acting on a wedge element of the tensioning device according to FIGS. 1 to 3 in a schematic illustration,

4b shows the static equilibrium of forces on the wedge element according to FIG. 4a in a vector illustration, FIG.

4c shows the dynamic equilibrium of forces on the wedge element according to FIG. 4a in the case of a pivoting movement of the tensioning lever that excites the torsion spring in a vector illustration, FIG.

4d shows the dynamic equilibrium of forces on the wedge element according to FIG. 4a in the case of a pivoting movement of the tensioning lever which relaxes the torsion spring in a vector representation, FIG.

5 shows an alternative embodiment of a clamping device according to the invention in a partially sectioned axial view,

6a a bearing ring of a further embodiment of the clamping device according to the invention in a schematic axial view,

6b shows a tensioning lever of the further variant of the tensioning device according to the invention according to FIG. 6a in a schematic axial view, FIG.

7 shows a first embodiment of a spring force support of the torsion spring of the tensioning device in a schematic axial view, and FIG. 8 shows a second embodiment of a spring force support of the torsion spring of the tensioning device in a schematic sectional view.

Detailed description of the drawings

Since the basic structure and operation of the generic, with DE 102 006 014 942.4 has already been described and explained in detail in DE 102 006 014 942.4, the following description is limited to the novel features of the present invention.

A preferred embodiment of the tensioning device 1 according to the invention of a traction mechanism drive is shown in FIG. 1 in a perspective exploded view. In a so-called offset or Z arrangement, a tensioning lever 2 is mounted rotatably on a cup-shaped base housing 4 via a pivot bearing 3. Radially spaced from the axis of rotation 5 of the pivot bearing 3, the clamping lever 2 is provided with a present not shown, about an axially parallel axis of rotation 6 rotatable tension roller over which the traction means of a traction mechanism is guided in the installed state.

The pivot bearing 3 is presently cylindrical and is formed of a rigidly connected via a serration 7 to the base housing 4 bearing pin 8, a rigidly connected to the clamping lever 2 bearing hub 9 and arranged between the bearing pin 8 and the bearing hub 9 plain bearing bush 10. For axial bearing of the clamping lever 2, a Gleitla- gerscheibe 11 is provided, which is integrally connected to the plain bearing bush 10 and between a lever-fixed bearing plate 12 and a rigidly connected to the bearing pin 8 bearing plate 13 is arranged. The clamping lever 2 and the base housing 4 are positively connected to each other via a torsion spring 14 in operative connection, which is designed as a load-bearing in the open sense legless coil spring 15 with blunt spring ends 16, 17 and coaxial with the pivot bearing 3.

In the installed state, the tensioning lever 2 is acted upon by tensioning the associated traction means by means of the helical spring 15 with a torsional moment M _τ about the axis of rotation 5 of the pivot bearing 3, whereby the tensioning roller springs over the tensioning lever 2 to the traction means and thus the traction means is tense.

Between the outer lever-side turn 18 of the coil spring 15 and the tensioning lever 2, a bearing ring 19 made of a durable plastic is arranged. As can be seen more clearly in the enlarged detail of FIG. 1 in FIG. 2 and in the axial view of the bearing ring 19 in FIG. 3, the lever-side spring end 16 of the torsion spring 14 is connected to the tensioning lever 2 via a wedge element 20 and a lever-fixed driver 21 , The wedge element 20 rests with an axially-radially aligned pressure surface 22 on the lever-side spring end 16 of the helical spring 15 and with a wedge surface 23 inclined radially outward from the lever-side spring end 16 on an equally inclined wedge surface 24 of the driver 21 and with an outer cylindrical friction surface 25 on a cylindrical inner wall 26 of the base housing 4 at.

In the present embodiment of the tensioning device 1, the wedge member 20 and the driver 21 are integrally connected to the bearing ring 19. The bearing ring 19 is positively secured near the driver 21 against the clamping lever 2 against rotation and against radial displacement, and provided between the wedge surface 23 of the wedge element 20 and the wedge surface 24 of the driver 21 with a separating slot 27.

The positive connection of the bearing ring 19 with the clamping lever 2 is presently formed by an axially aligned inner radial groove 28 of the bearing ring 19 and an engaging in this axially extending outer radial web 29 of the clamping lever 2. To dampen vibrations of the coil spring 15, the bearing ring is also provided with sleeve segments 30 which abut radially in the mounted state on the turns of the coil spring 15.

To illustrate the balance of forces on the wedge element 20 are in FIG. 4 a shows the forces acting on the wedge element 20 according to FIG. 3. Normally, ie perpendicular to the pressure surface 22 of the wedge element 20, the tangential spring force F _F _τ of the spring end 16 of the helical spring 15 acts normally on the wedge surface 23 of the wedge element 20, the reaction force of the driver 21 acts on the support force F _{KN of} the wedge element 20, and normal or radial to the friction surface 25 of the wedge element 20 acts the reaction force of the cylindrical inner wall 26 of the base housing 4 to the radial pressing force F R of the wedge element _κ 20th

In one respect to the Torsisonsfeder 14 are compressing the pivoting movement 31 of the tensioning lever 2 in addition, the frictional force by drawn represented F _R T on the friction surface 25 of the wedge element acts 20 in a direction directed ausfedernden pivoting movement 32 of the tensioning lever 2 in the opposite direction, the frictional force F _RT shown in dashed lines acting on the Friction surface 25 of the wedge element 20th

In Fig. 4b, the static force equilibrium is shown on the wedge member 20, which adjusts at a certain position of the clamping lever 2 without a pivoting movement. In Fig. 4c, the dynamic balance of forces on the wedge member 20 is shown, which adjusts itself at a certain position of the clamping lever 2 during a torsional spring 14 einfedernden pivotal movement 31 of the clamping lever 2, resulting in an increase in the radial contact force F _{KR of} the wedge member 20 and Consequently, an increase in the friction damping of the pivoting movement 31 results.

FIG. 4d shows the dynamic equilibrium of forces on the wedge element 20 which, at a specific position of the tensioning lever 2, adjusts during a pivoting movement 32 of the tensioning lever 2 which rebounds with respect to the torsion spring 14, resulting in a reduction in the radial contact pressure F _{KR of} the wedge element 20 and consequently a reduction in the frictional damping of the pivoting movement 32 sets. This ensures tet, that the clamping lever 2 opposes an outward swinging of the traction means an increased resistance, whereas an inward swinging of the traction means, a reduced resistance is opposed, so that the tensioning lever 2 mounted on the tension roller follows the movement of the traction means and remains in contact therewith.

An alternative embodiment of the tensioning device 1 'according to the invention is shown in FIG. 5 in a simplified, partially sectioned axial view as viewed from the base housing to the outer tensioning lever 2. The tensioning lever 2 is urged by the helical spring 15 in the opposite direction of rotation to the tensioning device 1 according to FIGS. 1 to 3 with the torsional moment M _τ , whereby the tensioning roller 33 is spring-loaded to an associated traction means and a resultant reaction force Fz R to the tensioning roller 33 or the tensioning lever 2 is generated. The wedge element 20 and the driver 21 are, as in the previously described embodiment, integrally connected to the bearing ring 19, which consists of an elastic and resistant plastic, is arranged between the outer winding 18 of the helical spring 15 and the tensioning lever 2 between the wedge surfaces 23, 24 of the wedge member 20 and the driver 21 has a separating slot 27 exaggerated here.

For the most complete compensation of a caused by the reaction force F _Z _ _{R of} the pulling means on the tensioning roller 33 tilting moment about a tilt axis of the pivot bearing, the wedge surfaces 23, 24 of the wedge element 20 and the driver 21 are largely normal to the reaction force F _Z _ _R aligned. The non-rotatable and radially fixed connection of the bearing ring 19 with the clamping lever 2 is present, as indicated in Fig. 5, in the form of a close to the driver 21 on the bearing ring 19 arranged axial bore 34, an arranged on the clamping lever 2 axial bore 35 and a in the axial bores 34, 35 used bolt 36 is formed. Depending on the application, the lever-side axial bore 35 can be arranged in different angular positions. Ones are attached, so that the use of a largely identical clamping lever 2 in several different clamping devices is possible.

A further embodiment variant of the tensioning device 1 "according to the invention is shown in FIGS. 6a and 6b in each case in a simplified, partially cut axial view looking from the base housing to the outer tensioning lever 2. FIG. 6a shows the lever-side bearing ring 19 'with the outer lever side Winding 18 of coil spring 15, while Fig. 6b shows tensioning lever 2 with tensioning roller 33. Wedge element 20 is integrally connected to bearing ring 19 'which has a radially continuous opening 37 immediately adjacent wedge surface 23 of wedge element 20 Driver 21 with the local wedge surface 24 is in this case practically in the clamping lever 2 'integrated by this is provided with a limited by the wedge surface 24 radial groove 38 in the mounted state, an axial extension of the wedge element 20 engages with its wedge surface 23 Tension lever 2 'even with a jig with entgegenges To be able to use the last pivoting direction, the radial groove 38 is circumferentially opposite by a further wedge surface 24 'limited.

In Fig. 7, the lever-side support of the reaction force F _{FR of} the clamping lever 2 is shown in a schematic axial view of the coil spring 15 via a sliding block 39, whereby an additional friction torque for damping a pivoting movement of the clamping lever 2 is generated. The shoe 39 is disposed about the axis of rotation 5 of the pivot bearing 3 from the lever-side spring end 16 set back by about 90 °, is located radially inward on the outer lever-side winding 18 of the coil spring 15, is radially guided in a radial guide 40 of the clamping lever 2, and lies with an outer cylindrical friction surface 41 against a cylindrical inner wall 26 of the base housing 4. On the circumference of the lever-side spring end 16 side facing away from the side walls 42, 43 of the shoe 39 and the radial guide 40 aligned radially-parallel. On the circumference of the lever-side spring end 16 side facing the side walls 44, 45 of the shoe 39 and the radial guide 40, however, formed as radially outward to the lever-side spring end 16 inclined wedge surfaces, whereby the effective friction torque in a respect to the coil spring 15 einfedernden pivotal movement 31 of Clamping lever 2 is reinforced.

In the schematic sectional view according to FIG. 8, for the lever-side end of the helical spring 15 it is illustrated that the support of the reaction force F _{FR of} the helical spring 15 alternatively also results from direct contact of the outer lever-side turn 18 of the helical spring 15 with the cylindrical inner wall 26 of FIG Base housing 4 can be done. For this purpose, at least the outer lever-side winding 18 of the coil spring 15 is provided with a friction coating 46. In this case, however, the screw spring 15 is advantageously completely provided with a friction coating 46, since this can eliminate an otherwise required anticorrosion treatment of the helical spring 15.

C _Is

LIST OF REFERENCE NUMBERS

1 clamping device r clamping device

1 "clamping device

2 tension levers

clamping lever

3 swivel bearings

4 base housing

5 axis of rotation of clamping lever and pivot bearing

6 axis of rotation

7 serration

8 bearing bolts

9 bearing hub

10 plain bearing bush

11 plain bearing disc

12 storage plates

13 storage plates

14 torsion spring

15 coil spring

16 lever side spring end

17 Housing-side spring end

18 Outer lever-side winding of the coil spring

19 bearing ring

19 'bearing ring

20 wedge element

21 drivers

22 pressure surface of the wedge element

23 wedge surface of the wedge element 24 wedge surface of the driver 24 'wedge surface of the driver

25 friction surface of the wedge element

26 Inner wall in the base housing 27 Separating slot of the bearing ring

28 Radial groove of the bearing ring

29 Radial web of the clamping lever

30 sleeve segment

31 pivotal movement of the clamping lever 32 pivotal movement of the clamping lever

33 tension roller

34 axial bore of the bearing ring 19

35 Axial bore in the clamping lever

36 bolt 37 opening of the bearing ring 19 '

38 Radial groove in the clamping lever

39 sliding shoe

40 radial guide

41 friction surface of the shoe 42 side wall of the shoe

43 side wall of the radial guide

44 side wall, wedge surface of the sliding shoe

45 side wall, wedge surface of the radial guide

46 Friction Coil of the Coil Spring F _FR Radial reaction force (from 2, 20), supporting force of the coil spring

F _FT Tangential spring force (from 15, 20)

F _κ N Normal support force (from 20, 21)

F _{κ R} Radial contact pressure (from 20, 26)

F _RT Tangential friction force (from 20, 26) Fz _R Radial reaction force of the traction device

M _τ torsional moment (from 14, 15)

Claims

claims 1. Tensioning device of a traction mechanism drive, with a clamping lever (2) mounted rotatably on a base housing (4) via a pivot bearing (3) and radially spaced from the axis of rotation (5) of the pivot bearing (3) with a rotatable tension roller (33) , by means of a thighless helical spring (15) formed coaxially to the pivot bearing (3) and arranged at the spring ends (16, 17) housing side with the base housing (4) and lever side with the clamping lever (2) in operative connection torsion spring (14) with a torsional moment (M _τ ) about the axis of rotation (5) of the pivot bearing (3) can be acted upon, wherein the pivot bearing (3) by a bearing pin (8), a bearing hub (9) and at least one between the bearing pin (8 ) and the bearing hub (9) arranged plain bearing bush (10) is formed, and wherein a mean radial force application plane of the Tensioning pulley to a central radial bearing plane of the pivot bearing (3) is axially spaced, characterized in that the lever side or housing side spring end (16) of the torsion spring (14) via at least one wedge element (20) and a lever-fixed driver (21) with the Tension lever (2) is in communication, wherein the wedge element (20) with an axially-radially aligned pressure surface (22) on the lever side spring end (16) of the coil spring (15) rests, with a radially outward of the lever-side spring end ( 16) away inclined wedge surface (23) on an equally inclined wedge surface (24) of the driver (21) is present, and with an outer cylindrical friction surface (25) on a cylindrical inner wall (26) of the base housing (4). 2. Clamping device according to claim 1, characterized in that the driver (21) with respect to the axis of rotation (5) of the pivot bearing (3) on the circumference side arranged such that the wedge surfaces (23, 24) of the wedge element (20) and the driver (21) is largely normal to a sultierenden reaction force (F _Z _ _R ) of a traction device on the tension roller (33) are aligned. 3. Clamping device according to claim 1 or 2, characterized in that the angle of inclination of the wedge surfaces (23, 24) of the wedge element (20) and the driver (21) opposite the pressure surface (22) of the wedge element (20) in a range between 30 ° and 60 °. 4. Clamping device according to at least one of claims 1 to 3, character- ized in that the friction surface (25) of the wedge element (20) and / or the cylindrical inner wall (26) of the base housing (4) is provided with a friction lining. 5. Clamping device according to at least one of claims 1 to 4, character- ized in that the entire wedge element (20) consists of a resistant and abrasion-resistant plastic. 6. Clamping device according to at least one of claims 1 to 5, characterized in that the wedge element (20) is integrally connected to an open bearing ring (19) between the outer lever-side turn (18) of the coil spring (15) and the Tension lever (2) is arranged, which is spaced from the wedge element (20) against the clamping lever (2) positively secured against rotation, and which is fully opened immediately adjacent to the wedge surface (23) of the wedge element (20). 7. Clamping device according to claim 6, characterized in that the wedge element (20) protrudes at least partially axially outward from the bearing ring (19 ') and into a with the lever-side wedge surface (24') verse- hene radial groove (38) of the clamping lever (2 ) intervenes. 8. Clamping device according to claim 7, characterized in that the radial groove (38) of the clamping lever (2) in the circumferential direction on both sides with a wedge surface (24, 24 ') is provided. 9. Clamping device according to at least one of claims 1 to 5, characterized in that the wedge element (20) and the driver (21) are integrally connected to a slotted bearing ring (19) between the outer lever-side winding (18) of the coil spring ( 15) and the clamping lever (2) is arranged, the close to the driver (21) against the clamping lever (2) positively against a Twisting and secured against a radial displacement, and between the wedge surface (23) of the wedge element (20) and the wedge surface (24) of the driver (21) is provided with a separating slot (27). 10. Clamping device according to claim 9, characterized in that the positive connection of the bearing ring (19) with the clamping lever (2) by an axial bore (34, 35) and in the axial bores (34, 35) inserted bolt (36) becomes. 11. Clamping device according to claim 9, characterized in that the positive connection of the bearing ring (19) with the clamping lever (2) by an axially extending inner radial groove (28) of the bearing ring (19) and engaging in this axially extending outer radial web (29 ) of the clamping lever (2) is formed. 12. Clamping device according to at least one of claims 1 to 11, characterized in that the housing-side spring end (17) of the torsion spring (14) via a wedge element and a housing-fixed carrier with the base housing (4) is in communication, wherein the KeN element with an axially-radially aligned pressure surface on the housing-side spring end (17) of the coil spring (15) rests, with a radially outwardly of the housing-side spring end (17) inclined wedge surface rests against an equally inclined wedge surface of the driver, and with an outer cylindrical friction surface on a cylindrical inner wall of the clamping lever (2). 13. Clamping device according to claim 12, characterized in that the housing-fixed carrier with respect to the axis of rotation (5) of the pivot bearing (3) is circumferentially arranged such that an imaginary, the radial contact force (F _KR ) of the wedge element containing radial surface substantially parallel to the resulting Reaction force (F _Z _ _R ) of the traction device is aligned with the tension roller (33). 14. Clamping device according to at least one of claims 1 to 13, characterized in that the lever-side support of the reaction force (F _FR ) of the clamping lever (2) on the coil spring (15) via a sliding shoe (39), which is about the axis of rotation (5) of the pivot bearing (3) from the lever-side spring end (16) is arranged offset by about 90 °, radially inwardly against the outer lever-side winding (18) of the coil spring (15), in a radial guide (40) of the clamping lever ( 2) is guided radially movable, and with an outer cylindrical friction surface (41) against a cylindrical inner wall (26) of the base housing (4), wherein the sliding shoe (39) and the radial guide (40) circumferentially on the lever-side spring end (16) facing Side each have a radially outward to the lever-side spring end (16) inclined wedge surface (44, 45). 15. Clamping device according to at least one of claims 1 to 14, characterized in that the housing-side support of the reaction force (F _FR ) of the base housing (4) on the coil spring (15) ü via a sliding shoe takes place about the rotation axis (5). of the pivot bearing (3) from the housing-side spring end (17) from about 90 ° to is set back, radially inwardly abuts the outer housing-side winding of the helical spring (15), is radially movably guided in a radial guide of the base housing (4) and bears against an outer cylindrical friction surface on a cylindrical inner wall of the clamping lever (2), wherein the sliding shoe and the radial guide on the circumferential side on the housing-side spring end (17) facing side each have a radially outward to the housing-side spring end (17) inclined wedge surface. 16. Clamping device according to claim 14 or 15, characterized in that the angle of inclination of the wedge surfaces of the shoe and the radial guide relative to an imaginary, the axis of rotation (5) of the pivot bearing (3) and the outer cylindrical friction surface of the shoe in approximately halving the radial plane in one area between 30 ° and 60 °. 17. Clamping device according to at least one of claims 14 to 16, characterized in that the sliding shoe (39) is integrally connected to the associated bearing ring (19). 18. Clamping device according to at least one of claims 1 to 13, characterized in that the lever-side support of the reaction force (F _FR ) of the clamping lever (2) on the coil spring (15) via an immediate contact of a about the axis of rotation (5) of the pivoting Bearing (3) from the lever-side spring end (16) from about 90 ° back portion of the outer lever-side winding (18) of the coil spring (15) with a cylindrical inner wall (26) of the base housing (4), wherein at least the outer lever-side winding (18) of the coil spring (15) and / or the cylindrical inner wall (26) of the base housing (4) is provided with a friction coating (46). 19. Clamping device according to at least one of claims 1 to 13 or 18, characterized in that the housing-side support of the reaction force (F _FR ) of the base housing (4) on the coil spring (15) via an immediate contact of a about the axis of rotation (5) Pivot bearing (3) from the housing side spring end (17) from about 90 ° back portion of the outer housing side winding of the coil spring (15) with a cylindrical inner wall of the clamping lever (2), wherein at least the outer housing side winding of the coil spring (15) and / or the cylindrical inner wall of the clamping lever (2) is provided with a friction coating (46). 20. Clamping device according to claim 18 or 19, characterized in that the helical spring (15) is completely provided with a friction coating (46).