WO2004015304A2

WO2004015304A2 - Tensioning device for a drive with a traction mechanism

Info

Publication number: WO2004015304A2
Application number: PCT/EP2003/008207
Authority: WO
Inventors: Manfred Wilhelm; Thomas Ebner
Original assignee: Ina-Schaeffler Kg
Priority date: 2002-08-03
Filing date: 2003-07-25
Publication date: 2004-02-19
Also published as: AU2003250176A1; DE10235540B4; DE10235540A1; WO2004015304A3

Abstract

The invention relates to a tensioning device (1) for a drive with a traction mechanism, wherein said tensioning device (1) has a supporting body (2) that is supported on a machine part (3) on bearing surface (16) oriented opposite the longitudinal axis (A) of the supporting body (2).

Description

Clamping device for a traction mechanism drive

Field of the Invention

The invention relates to a tensioning device for a traction mechanism drive, which comprises an elastic traction device, in particular a belt. The tensioning device is positionally positioned on a machine part on a supporting body, on which a working eccentric that can be rotated to a limited extent against a spring force is mounted. A roller bearing roller that surrounds the work eccentric is supported in the installed state directly on the traction means.

Background of the Invention

A tensioning device according to the type described above is known from DE 199 13 212 A1. In tensioning devices of this type, the roller is supported by a spring force on the traction means, in particular a belt, in order to achieve sufficient pretension. This constant pre-tensioning force does not result in the large-scale application of force from the work eccentric to the supporting body as desired, but rather an edge support. This is triggered in particular by the fact that the contact area of the traction means on the roller changes in the operating state. As soon as there is a certain misalignment due to wear, caused by an enlarged annular gap between the support body and the work eccentric, the traction element contact surface shifts outwards, ie away from the machine part. Extreme wear can it comes to a running of the traction device from the roller and thus to the failure of the traction drive.

Summary of the invention

The present invention has for its object to provide a tensioning device which includes effective measures to prevent misalignment of the roller.

This object is achieved by the characterizing features of claims 1, 2 and 10.

According to claim 1, in order to compensate for a misalignment between the longitudinal axis of the support body and the longitudinal axis of the working eccentric, the support body is supported on the machine part via a contact surface deviating from a right-angled alignment with the longitudinal axis of the support body. A certain deliberate misalignment is thus achieved, whereby influences such as manufacturing tolerances, bearing play and elastic deformations of individual components are compensated for when the clamping device is installed. Furthermore, this deliberate misalignment prevents play caused by wear and also avoids disadvantageous edge wear in the area of an outer contour, via which the work eccentric is supported indirectly or directly on the supporting body. The degree of misalignment is selected so that in the installed state there is a largely right-angled arrangement of the roller surface line to the support surface of the support body on the machine part.

To solve the invention it is provided according to claim 2 that at least one of the different contact surfaces of the clamping devices is designed to compensate for a misalignment deviating from a cylindrical shape. The surface area of the supporting body or the receiving bore of the working eccentric count as important contact surfaces of the clamping device. These constructive measures cause one when installed deliberate balancing of the installation play of the individual components. For example, with a lead angle, which can also be called a positive misalignment, a wear-related misalignment of the roller can be compensated. This effect can also be achieved by designing the outer surface of the roller to deviate from a cylindrical shape. This feature also compensates for wear and play and enables a largely parallel assignment of the outer surface of the roller to the longitudinal axis of the tensioning device and thus at the same time a right-angled guidance of the traction device to the machine part or all the longitudinal axes of the units that the traction mechanism drive includes.

To solve the invention, a method is also provided according to claim 10, with which at least one component of the tensioning device is manufactured and designed such that an alignment deviation starting from a right-angled alignment of the longitudinal axis of the supporting body of = 1.5 ° can be realized.

As a suitable method, mechanical processing is provided, with which the contact surface of the supporting body and / or its outer surface is machined in such a way that a desired inclination, a lead angle or a positive misalignment is set in order to avoid edge wear or to compensate a negative misalignment. A further suitable method provides for the contact surface and / or its outer surface to be correspondingly molded in a support body designed as a cast part. For this purpose, a casting process is advantageously provided, with which the supporting body can be manufactured with the required misalignment without aftertreatment. Such a method can also be used to manufacture the work eccentric. The invention further includes an injection molding process for manufacturing the roller made of plastic. By means of an adapted casting mold, the component can be manufactured in such a way that it can be removed from the casting mold without reworking with the features according to the invention. This is an inexpensive manufacture of this Components achievable, which is particularly advantageous for clamping devices manufactured in large quantities.

Further advantageous embodiments of the inventions according to claims 1 and 2 are the subject of dependent claims 3 to 9.

Another advantageous development of the inventions provides that they can also be transferred to double eccentric clamping devices. For this purpose, the tensioning device is additionally provided with an adjustment eccentric which, when installed, is arranged between the support body and the work eccentric and with which an enlarged adjustment range of the tensioning device can be achieved.

Alternatively, the support body can simultaneously take over the function of the setting eccentric.

A bearing-oriented attachment of the support bolt to the machine part is expediently carried out. This measure is intended in particular for clamping devices, the supporting bolts of which have an inclined contact surface which consequently deviates from a right-angled alignment with the longitudinal axis of the supporting body. The position-oriented fastening can be designed, for example, in connection with an anti-rotation device. Furthermore, it is advisable to design a guide pin between the machine part and the support bolt in such a way that it only allows these components to be joined together in a defined installation position.

The invention is also transferable to clamping devices in which a plain bearing bushing is used in an annular gap delimited radially by the supporting body and the working eccentric or the adjusting eccentric. The task is to produce a friction-free, wear-free adjusting movement of the working eccentric and thus the tensioning roller relative to the supporting body. The inventions include differently geometrically designed contact surfaces of the clamping device. One solution provides for the support body to be provided with a conically shaped outer surface, a support body diameter tapering continuously from the free end in the direction of the machine part. Such a support body is combined with a work eccentric or adjustment eccentric which has a cylindrical receiving bore. This combination opposes an edge loader in which the roller is supported on the outside due to the installation play and an off-center force transmission. Due to wear, the inclined position of the roller increases, which can lead to the traction device running off the roller. The conically shaped outer surface of the support body, which is preferably designed in such a way that a lead angle is set, which means that, in the installed state, play caused by wear is simultaneously associated with an increase in the contact area, which slows the misalignment.

This effect can also be achieved by the plain bearing bush having a conically shaped outer surface, the diameter of which also tapers continuously in the direction of the machine part when installed.

It also makes sense to provide the roller with a conically shaped surface on which the traction means is guided directly. Here too, the conical shape is selected such that the largest diameter of the roller is provided on the roller side, which tends to wear due to wear.

Brief description of the drawings

In the following description, exemplary embodiments of the invention are described in more detail. Show it:

1 shows a longitudinal section of a tensioning device in the installed state; Figure 2 shows the tensioning device according to claim 1, the roller is inclined to the installation or slide bearing play;

Figure 3 shows a clamping device in which the contact surface of the support body is inclined to compensate for the game;

Figure 4 shows a conically shaped support body of the tensioning device as a measure to compensate for play;

5 shows a clamping device with a conically shaped

Plain bearing, which is intended to compensate for play;

FIG. 6 shows a tensioning device, the roller of which comprises a conically shaped outer surface;

Figure 7 in longitudinal section a double eccentric clamping device, in which the support surface of the support pin is directed obliquely to compensate for play.

Detailed description of the drawings

FIG. 1 shows a longitudinal section of the tensioning device 1, consisting of a support body 2 which is attached to a machine part 3 in a rotationally fixed manner. The support body 2 is enclosed by a work eccentric 4, which is arranged such that it can be rotated to a limited extent directly on the lateral surface of the support body 2 or via a slide bearing 5. The longitudinal axis "A" of the supporting body 2 is offset by a dimension "S" from a longitudinal axis "B" of the working eccentric 4. The dimension "S" defines the maximum eccentricity of the working eccentric 4 and thus the adjustment range of the working eccentric 4 relative to the supporting body 2. An inner ring 8 of the roller bearing 7 is positioned on a lateral surface 6 of the working eccentric 4. The associated outer ring 9 of the roller bearing 7 is enclosed by the roller 10, which in the installed state of the tensioning device 1 a traction means, a belt 11 is supported. A torsion spring 12, which is supported with a spring end on the work eccentric 4 and the further spring end on a torsionally rigid shield plate 13 connected to the supporting body 2, causes the work eccentric 4 to act automatically and continuously, thereby causing the belt 11 to be pretensioned increasing position is rotated. Opposite to the torsion spring 12, the working eccentric 4 is supported on a stop 14, a sliding washer 15 being arranged between the stop 14 and the working eccentric 4 as a measure for reducing wear and friction. FIG. 1 shows the clamping device 1 in an ideal state, in which the longitudinal axes “A” and “B” of the supporting body 2 and the working eccentric 4 run coaxially or parallel to one another.

FIG. 2 shows the roller 10 in an oblique position with respect to the support body 2. The oblique position, characterized by the negative misalignment "" "between the longitudinal axes" A "and" B ", is caused by a belt force" F "which is introduced into the tensioning device 1 via the outer surface of the roller 10. An existing installation play, which arises due to manufacturing tolerances in connection with wear, in the operating state, causes an edge load, i. H. Instead of coaxial support of the working eccentric 4 on the slide bearing 5 or the supporting body 4, a tilting occurs, the working eccentric 4 being supported via an edge zone assigned to the stop 14. The edge support causes a significant increase in the surface pressure, which further increases the wear and thus increases the tilting or misalignment of the roller 10. The abutment of the belt 11 on the lateral surface of the roller 10 changes in synchronism with the inclination of the roller, associated with the risk that the belt 11 runs off the roller 10.

FIGS. 2 to 6 each show the tensioning device 1, with a structure that largely corresponds to FIG. 1. Therefore, only the distinctions are described in the descriptions of FIGS. wrote. Matching components are provided with the same reference numbers.

FIG. 3 shows a measure according to the invention to compensate for the negative misalignment “<x”. For this purpose, the support body 2 is provided with a contact surface 16 that is designed to be oblique with respect to the longitudinal axis “A” of the support body 2. The inclined position of the contact surface 16 is characterized by the angle ".beta.", Which defines a positive misalignment. The inclined contact surface 16 requires a position-oriented installation of the support body 2. For this purpose, an anti-rotation device 17 is provided, consisting of an axially projecting shoulder 18 of the support body 2, which in the installed state of the clamping device 1 engages in a recess 19 in the machine part 3. Preferably, the inclined contact surface 16 of the support body 2 is designed such that the positive misalignment characterized by the angle ".beta." Exceeds the angle ".alpha." that manufacturing-related installation tolerances or all bearing clearances are compensated for and, when new, there is a large-area support between the work eccentric 4 and the slide bearing 5 or the support body 2. The measure according to the invention avoids edge wear and the associated impermissibly high F surface pressure that triggers a premature failure of the tensioning device 1.

As an alternative measure to avoid the disadvantageous edge wear between the work eccentric 4 and the support body 2, the tensioning device 1 is provided with a conically shaped work eccentric 4 according to FIG. The taper is designed such that the outer diameter of the working eccentric 4 tapers continuously starting from the free end, ie from the area of the stop 14. The limit diameters are identified by "di" and "d ₂ ". The difference between these diameters is designed in such a way that it compensates for the installation clearance or installation tolerances and, consequently, a parallel arrangement between the longitudinal axes “A” and “B” occurs in the installed state. To simplify assembly, it is provided that the support body 2 installed in a position-oriented manner has a work eccentric 4 is assigned, the receiving bore = the largest diameter of the working eccentric, the diameter "di" corresponds.

As an alternative to the solution according to FIG. 4, the clamping device 1 shown in FIG. 5 shows a conically designed slide bearing 5. In the installed state, the slide bearing 5 with the largest outside diameter "di" is assigned to the stop 14. The outside diameter tapers from the diameter "di" continuously down to the smallest diameter "d ₂ ". With the conical slide bearing 5, an effect matching the conical support body 2 according to FIG. 5 can be achieved in order to prevent disadvantageous misalignment of the roller in the installed state.

FIG. 6 shows the tensioning device 1, in which the roller 10 has a conical shape

Has outer surface 20. This conical shape of the lateral surface 20 is also designed in such a way that it compensates for the negative misalignment, the angle “.alpha.” Between the longitudinal axes “A” and “B.” For this purpose, the diameter of the lateral surface 20 widens continuously starting from the shield plate 13 the entire width of the lateral surface.

FIG. 7 shows the clamping device 21, which is constructed as a double eccentric clamping device. The tensioning device 21 is attached to the machine part 3 (not shown in FIG. 7) in a position-oriented manner via a supporting body, designed as an adjusting eccentric 22. The working eccentric 24 is arranged to be rotatable to a limited extent on the lateral surface 23 of the setting eccentric 22. The work eccentric 24 serves to receive the roller bearing 25, which is enclosed by the roller 26. In the ideal case, all longitudinal axes, the longitudinal axis “A” of the adjusting eccentric 22, the longitudinal axis “B” of the working eccentric 24, the longitudinal axis “C” of the bore for receiving a fastening screw 27 for the clamping device 21 run parallel. To compensate for an inclined position of the tensioning device 21 or a negative misalignment “α” as explained in the above-mentioned exemplary embodiments, the adjusting eccentric 22 is supported on the machine part 3 via an obliquely running contact surface 28. The course of the contact surface 28 is through the Marked angle "Y", which defines the deviation of the contact surface 28 from a leg oriented at right angles to the longitudinal axes "A" to "C".

reference numerals

jig

supporting body

machinery

working eccentric

bearings

lateral surface

roller bearing

inner ring

outer ring

caster

belt

torsion spring

shield plate

attack

sliding disk

contact surface

twist

approach

recess

lateral surface

jig

adjusting eccentric

lateral surface

working eccentric

roller bearing

caster

fixing screw

contact surface

Claims

claims

1. Tensioning device (1, 21) for a traction drive, comprising an elastic traction device, in particular a belt (11), the tensioning device (1, 21) being positioned on a machine part (3) via a support body (2) on which a the work eccentric (4), which can be rotated to a limited extent against a spring force, and the work eccentric

(4) surrounding roller bearing roller (10, 26) is supported on the traction means, characterized in that to compensate for a negative misalignment (α) between the longitudinal axes (A, B) of the support body (2) and the working eccentric (4), the support body (2) has a right-angled orientation to the support body

Longitudinal axis (A) deviating contact surface (16) on the machine part

(3) is supported.

2. Tensioning device (1, 21) for a traction mechanism drive, comprising an elastic traction device, in particular a belt (11), the tensioning device (1, 21) being positioned on a machine part (3) via a support body (2) which is supported by a work eccentric (4) which can be rotated to a limited extent against a spring force, and the work eccentric

(4) surrounding, roller-mounted roller (10, 26) is supported on the traction means, characterized in that at least one of the

Contact areas such as:

an outer surface of the support body (2); a receiving bore of the working eccentric (4); - lateral surface of the roller (26),

deviates from a cylindrical shape.

3. Clamping device according to one of claims 1 or 2, wherein the working eccentric (24) is arranged surrounding a setting eccentric (22) attached to the machine part (3).

4. Clamping device according to claim 1, wherein the support body (2) is fixed in a position-oriented manner on the machine part (3),

5. Clamping device according to claim 1 or claim 2, in which in a radially from the support body (2) or adjusting eccentric (22) and the working eccentric (4, 24) limited space, a plain bearing (5) is used.

6. Clamping device according to claim 2, the support body (2) of which has a conically shaped outer surface, a support body diameter (di) tapering continuously in the direction of the machine part (3).

7. Clamping device according to claim 5, wherein the slide bearing (5) guided on the support body (2) has a conically shaped lateral surface, the largest diameter (di) of which tapers continuously in the direction of the machine part (3).

8. Clamping device according to claim 2, the roller (26) of which has a conically shaped outer surface (20), the diameter of which continuously increases starting from the side facing the machine part (3).

9. Clamping device according to one of claims 1 or 2, the support body (2) or the adjusting eccentric (22) of which with the machine part (3) form an anti-rotation device (17).

10. A method for producing and designing at least one component of the tensioning device according to claims 1 or 2, characterized in that with the starting from a right-angled direction to the longitudinal axis of the supporting body (A) a positive misalignment (ß) of ≤ 1.5 ° is provided.

11. The method according to claim 10, in which the contact surface (16, 28) and / or the outer surface of the support body (2) or the adjusting eccentric (22) is produced by means of mechanical processing.

12. The method according to claim 10, wherein the components designed as a casting support body (2) and adjusting eccentric (22) are molded in such a way that their contact surface (16, 28) or the lateral surface thereof allow compensation of the negative misalignment (α).