WO2001071216A1

WO2001071216A1 - Tensioning device for traction mechanisms

Info

Publication number: WO2001071216A1
Application number: PCT/EP2001/002006
Authority: WO
Inventors: Michael Schmid
Original assignee: Ina-Schaeffler Kg
Priority date: 2000-03-21
Filing date: 2001-02-22
Publication date: 2001-09-27
Also published as: DE10013978A1

Abstract

The invention relates to a tensioning device for traction mechanisms, comprising a tension arm (7) that can be swiveled with respect to the housing (2) and that is elastically attached to a traction mechanism (10) via a torsion spring (11). A spring end (13) of the torsion spring (11) rests indirectly on the housing (2) via a spring support (20a).

Description

Tensioning device for traction devices

Field of the Invention

The invention relates to a tensioning device for traction means, such as belts and chains, which is used, for example, in a traction mechanism drive of an internal combustion engine, in order to achieve a slip-free pretensioning of the traction means. The tensioning device comprises a stationary housing and a swivel arm which is rotatably arranged on a bearing journal of the housing via a hub. A tensioning means arranged with the tensioning arm, preferably a tensioning roller, is spring-supported on the tensioning means. For this purpose, a torsion spring is provided, the spring ends of which are fastened to the housing and to the tensioning arm.

Background of the Invention

From US-A 4,934,988 a tensioning device with a pot-shaped housing is known, in which a bearing journal is arranged centrally. The bearing journal serves to receive a hub, which is provided in one piece with a tension arm, with an end tensioning roller. The housing in connection with the tensioning arm forms an annular interior in which a torsion spring is inserted. The torsion spring used for the non-positive contact of the tensioning roller on the traction means is rotationally fixed with the spring ends directly on the housing and the tensioning arm. The torsion spring, which continues to exert an axial force, is supported axially with the spring ends on the housing made of metal or on the tensioning arm. In clamping devices used on internal combustion engines, load changes with the internal combustion engine running lead to deflections of the traction means, which are transferred to the clamping arm. The actuating movement of the tensioning arm causes a spring ends. This spring support leads to disadvantageous noise development and increased wear, particularly in the case of high-frequency adjusting movements of the tensioning arm.

Summary of the invention

Starting from the technical disadvantages of the known prior art, it is the object of the present invention to implement noise-optimized and wear-optimized support of the spring end within the specified installation space of the tensioning device.

This problem is solved according to the invention by a spring support designed as a multifunctional part. The design of the spring support made of plastic enables on the one hand axial support and on the other hand radial guidance or centering of the torsion spring. The invention consequently avoids direct support of the torsion spring on the housing or on the tensioning arm, i. H. between a torsionally rigid and the pivotable component, whereby decoupling and thus noise development are effectively prevented. The spring support made of plastic also provides a desired friction-reducing support and thus prevents wear on the spring end. In addition, the spring support according to the invention takes on the function of effectively sealing an annular gap between the torsionally rigid and a pivotable component. This further function of the spring support effectively prevents moisture or dirt particles from entering the annular gap, the slide bearing zone and lubricant from the area of the slide bearing, which has an advantageous effect on the function and service life of the bearing and thus the useful life of the entire tensioning device effect.

Further advantageous embodiments of the invention are the subject of claims 2 to 12, which are explained in more detail below.

An advantageous development of the invention provides that one for the torsion resistance to provide the support surface determined on the spring support with a continuous axial increase. The increase corresponds to the winding pitch of the torsion spring designed as a coil spring. This helical support surface caused an improved, large-area support of the torsion spring.

An advantageous embodiment of the invention provides for the arrangement of the spring support between a support disk fixed to the bearing journal of the housing and the spring end. The spring support is guided on a hub of the tensioning arm and provided at the end with a radially oriented, circumferential rim, on which the torsion spring is axially supported.

The spring support according to the invention can also be used according to the invention with a board between the support disk, which is rigidly connected to the housing, and an end face of the tensioning arm, the corresponding spring end of the torsion spring being supported on the board of the spring support.

The invention further includes a spring support for a tensioning device, in which the housing is provided with a torsionally rigid hollow pin, in which a bearing pin of the tensioning arm is rotatably guided. For such a tensioning device, a spring support is provided, the radially aligned rim of which rests on the tension arm and the spring end of the torsion spring is supported on the side of the spring support facing away from the tension arm.

In order to achieve a defined installation position, the spring support is provided according to the invention with a sleeve section which is guided on the hub of the tensioning arm or on a lateral surface of the hollow pin which is integrally connected to the housing. The structure of the spring support provides that a circumferential, radially aligned board adjoining the support disk or the tensioning arm adjoins the sleeve section at the end, on which mutually the torsion spring is supported over the spring end.

Effective centering of the spring end is achieved according to the invention on the spring support with a shoulder arranged radially offset from the sleeve section. For this purpose, the shoulder axially aligned in the direction of the torsion spring is preferably limited in length. The torsion spring is guided radially and thus centered on the circumferential or sectionally arranged shoulder.

The shoulder provided for centering on the spring support can be arranged differently on the radially oriented board of the spring support. The invention includes both a shoulder enclosing the spring on the outside and a shoulder on which the spring is guided.

The spring support made of plastic can furthermore be arranged according to the invention between the support disk, which is rigidly connected to the housing, and a hub of the tensioning arm. This installation position has the advantage of a further improved sealing of the annular gap between the clamping arm and the housing. For such an installation position, the sleeve sections with which the spring support is guided on the lateral surface of the tensioning arm or the housing can be omitted if required.

According to a further advantageous embodiment of the invention, the spring support is fixed in a torsionally rigid manner to the support disk or the tensioning arm. For example, the spring support can be glued or riveted to the associated component.

A suitable material for the spring support according to the invention is in particular a wear-resistant plastic with sufficient pressure-resistant properties, for example an elastomer. Brief description of the drawings

Preferred exemplary embodiments described in more detail below illustrate the invention. It shows:

1 shows a longitudinal section through a clamping device provided with a spring support according to the invention;

FIG. 2 shows the tensioning device shown in FIG. 1 with an alternatively designed spring support, the rim of which is inserted between an end face of the tensioning arm and a support disk of the housing;

Figure 3 shows a clamping device in a longitudinal section, in which the

Spring support between the tension arm and the torsion spring is arranged.

Detailed description of the drawings

In Figure 1, a tensioning device 1 is shown in a longitudinal section, which is provided for tensioning a traction mechanism drive, in particular a belt drive for an internal combustion engine. The structure comprises a stationary housing 2, on the bearing pin 3 of which a hub 4 is pivotally arranged. Between the hub 4 and the bearing pin 3, a slide bearing 6 is inserted in an annular gap 5, in order to achieve a low-friction pivoting movement of the hub 4. At one end of the hub 4 there is a clamping arm 7, which is at right angles to a longitudinal axis 8 of the housing 2 is aligned and provided at the end with a roller-mounted tensioning roller 9. A torsion spring 11 is provided to achieve a spring-loaded contact of the tensioning roller 9 with a traction means 10. For this purpose, the torsion spring 11 is arranged between a support disk 12, which is rigidly connected to the housing 2, and the tensioning arm 7, spring ends 13, 14 on the support disk 12, respectively the clamping arm 7 are fixed in position. Due to a pretensioned installation position of the torsion spring 11, an always supported contact of the tensioning roller 9 on the traction means 10 is ensured. In addition to a torsional force or a torque component, the torsion spring 11 continues to exert an expanding force acting in the axial direction, as a result of which the tensioning arm 7 is pressed onto a friction element 15 inserted between the housing 2 and the tensioning arm 7. The annular friction element 15 is adapted to a corresponding contact surface 16 of the clamping arm 7.

A spring support 20a according to the invention, which is designed as a multi-function part, is arranged between the spring end 13 facing away from the tension arm 7 and the support disk 12 which is rigidly attached to the housing 2. The torsion spring 11 is axially supported on the spring support 20a and is also guided or centered radially. As a measure to improve the support of the torsion spring 11, the spring support is provided with a continuously axially increasing support surface 37. The helical support surface is adapted to a pitch of the torsion spring 11. The structure of the spring support 20a comprises a sleeve section 17 which is guided on the lateral surface of the hub 4 and to which a flange 18 extending radially beyond the outer contour of the torsion spring 11 is connected at the end. Furthermore, the spring support 20a forms a shoulder 19 which is offset radially to the sleeve section 17 and on which the spring end 13 of the torsion spring 11 is centered. The shoulder 19 can be arranged both circumferentially and in sections. As can be seen in FIG. 1, the spring support 20a is supported on the inside of the support disk 12 over a large area, supported by the axial force of the torsion spring 11. This system effectively prevents the entry of contaminants of any kind into the annular gap 5 and lubricant leakage from the annular gap 5. The spring support 20a consequently continues to have a sealing function.

In a second exemplary embodiment (FIG. 2) of a tensioning device 1 according to the invention, the components which correspond to the first exemplary embodiment are provided with the same reference numerals, so that with regard to their Description can be made to the embodiment of the first embodiment.

In FIG. 2, the tensioning device 1 is provided with a spring support 20b, the rim 22 of which extends radially up to close to the outer contour of the bearing journal 3. This design forms an enlarged support surface of the spring support 20b and also improves the sealing function of the spring support 20b. In order to achieve a defined contact of the torsion spring 11 with the spring support 20b, it is advisable to attach the spring support 20b to the support disk 12 in a non-detachable manner. For example, gluing is suitable for this. As an alternative to gluing, the spring support 20b, which is preferably made of a plastic, can also be welded to the support disc 12. As an alternative to an inseparable connection, riveting and / or a form-fitting connection is suitable, for example in the form of a toothing profile between the rim 22 and the support disk 12, which is distributed in sections over the circumference.

FIG. 3 shows the tensioning device 21, which is provided with the spring support 20c, the structure of which largely corresponds to the spring support 20a shown in FIG. 1. The tensioning device 21 has a pot-shaped housing 23 with a centrally arranged hollow pin 24, which has a bearing pin 25 of the tensioning arm 26 rotatably arranged via a slide bearing 27. The torsion spring 28 inserted in the housing 23 is fixed in position with the spring ends 29, 30 on the tensioning arm 26 or the housing 23. The spreading force exerted by the torsion spring 28 provides a non-positive support for a support disk 31 which is fixed in a rotationally rigid manner on the bearing journal 25 on the housing 23. The friction element 32 inserted between the support disk 31 and the housing 23 serves to dampen actuating movements. The spring support 20c according to the invention is inserted in the clamping device 21 between the spring end 29 and the clamping arm 26. For this purpose, the spring support 20c is advantageously rotationally fixed to the tensioning arm 26, for example by gluing, so that when the tensioning arm 26 moves, the sleeve section 33 of the spring support 20c on a jacket surface of the sleeve 24 of the housing 23 slides. The spring support 20c which bears against the clamping arm 26 via the rim 34 is further provided with a shoulder 35 for centering the spring end 29 and furthermore provides an effective sealing function of the annular gap 36 predetermined by the slide bearing 27 between the bearing journal 25 and the inner diameter of the hollow journal 24.

reference numerals

Clamping device 30 spring end

Housing 31 support disc

Bearing journal 32 friction element

Hub 33 sleeve section

Annular gap 34 board

Slide bearing 35 shoulder

Clamping arm 36 annular gap

Longitudinal axis 37 support surface

idler

traction means

torsion spring

support disc

spring end

friction

contact area

sleeve section

shelf

Shoulder a spring rest b spring rest c spring rest

jig

shelf

casing

hollow pin

pivot

clamping arm

bearings

torsion spring

spring end

Claims

claims

1. tensioning device (1, 21) for traction means, such as belts and chains, with a stationary housing (2, 23) and a tensioning arm (7, 26) carrying a tensioning means, preferably a tensioning roller, which is opposite the housing (2, 23) rotatably mounted and inserted between the housing (2, 23) and the tension arm (7, 26)

Torsion spring (11, 28) via the tensioning roller (9) is sprung on the traction means (10), spring ends (13, 14; 29, 30) of the torsion spring (10, 28) on the housing (2, 23) or on the tensioning arm (7, 26) are fastened, characterized in that the torsion spring (11, 28) with at least one spring end (13, 29) on a spring support (20a, 20b, 20c) made of plastic and designed as a multifunctional part is axially supported and guided radially and the spring support (20a, 20b, 20c) also seals an annular gap (5, 36) between a torsionally rigid and a pivotable component of the tensioning device.

2. Clamping device according to claim 1, wherein the spring support (20a, 20b, 20c) has a continuous axially increasing course of a support surface (37) in the direction of the torsion spring (11, 28).

3. tensioning device for traction means according to claim 1, wherein the on the hub (4) of the clamping arm (7) guided spring support (20a) between a torsionally fixed to a bearing pin (3) of the housing (2) supporting disc (12) and the spring end ( 13) the torsion spring (11) is inserted (Figure 1).

4. tensioning device for traction means according to claim 1, wherein the spring support (20b) with a flange (22) between the torsionally rigid with the housing (2) connected support disc (12) and an end face of the tensioning arm (7) is arranged and the spring end (13) of the torsion spring (11) is supported on the spring support (20b) (Figure 2).

5. tensioning device for traction means according to claim 1, the spring support (20c) on one piece with the housing (23) connected

Hollow pin (24) is guided and the torsion spring (28) is supported via the spring end (29) on the radially aligned, on the clamping arm on the board (34) of the spring support (20c) (Figure 3).

6. tensioning device for traction means according to claim 1, wherein the spring support (20a, 20b) is guided over a sleeve section (17) on the hub (4) of the tensioning arm (7), with a circumferential, radially aligned board (18) adjoining the support disk (12), on which the torsion spring (11) is supported by the spring end (13) (FIG. 1, FIG. 2).

7. Tensioning device for traction means according to claims 5 and 6, the spring support (20a, 20b, 20c) of which is arranged radially offset radially to the sleeve section (17, 33), and for this purpose length-limited shoulder () 19, 35) on which the torsion spring (11, 28) is centered (Figure 1 to Figure 3).

8. tensioning device for traction means according to claim 7, wherein the shoulder (35) of the spring support (20c) at least limited length encloses the spring end (29) of the torsion spring (28) coaxially (Figure 3).

9. tensioning device for traction means according to claim 7, the torsion spring (11) with the spring end (13) encloses the shoulder (19) of the spring support (20a, 20b) (Figure 1, Figure 2).

10. tensioning device for traction means according to claim 1, the spring support (20a, 20b) is non-releasably attached to the support disc (12).

11. tensioning device for traction means according to claim 1, the spring support (20c) is non-detachably connected to the tensioning arm (26).

12. Tensioning device for traction means according to claim 1, wherein the spring support (20a, 20b, 20c) is made of an elastomer.