Belt tensioning device

Patent metadata

Field	Value
Publication number	US-9810296-B2
Application number	US-201514936982-A
Country	US
Kind code	B2
Filing date	Nov 10, 2015
Priority date	Nov 21, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A belt tensioning device comprises a base member having an attachment portion and an opening for a drive shaft; first and second tensioning arms that are pivotably supported by first and second bearings on the base member around first and second pivot axes and have first and second tensioning rollers 5, 7 . A spring arrangement pretensions the two tensioning arms in a circumferential direction towards each other; wherein the spring arrangement has at least one bow-shaped spring that has a circumferential extension of less than 360° around the first and the second pivot axis; wherein the at least one bow-shaped spring has first and second support portions that are supported on the first and second tensioning arm as well as a spring portion extending between the first and second support portion; wherein the at least one bow-shaped spring has an axial length in the area of the first and the second support portion which is axially shorter than a total axial length of the bow-shaped spring.

First claim

The invention claimed is:

1. A belt tensioning device comprising:
a base member that includes an opening for a drive shaft of an accessory and an attachment portion;
a first tensioning arm that is pivotably supported on the base member around a first pivot axis by a first bearing and has a first tensioning roller that is rotatable around a first axis of rotation;
a second tensioning arm that is pivotably supported on the base member around a second pivot axis by a second bearing, and that has a second tensioning roller that is rotatable around a second axis of rotation;
a spring arrangement that is arranged between the first tensioning arm and the second tensioning arm such that the first tensioning arm and the second tensioning arm are pretensioned in circumferential direction relative to each other by the spring arrangement;
wherein the spring arrangement comprises at least one bow-shaped spring that has a circumferential extension of less than 360° around the first and the second pivot axis,
wherein the at least one bow-shaped spring has a first support portion that is supported on the first tensioning arm, and a second support portion that is supported on the second tensioning arm, as well as a spring portion extending between the first support portion and the second support portion,
wherein the at least one bow-shaped spring has an axial length in the area of the first and the second support portion, which axial length is shorter than a total axial length of the bow-shaped spring.

2. The belt tensioning device of claim 1 ,
wherein a cross-sectional area of the bow-shaped spring is constant along the circumferential extension, wherein at least a central region of the spring portion is axially offset relative to the first and the second support portion in a direction towards a center plane formed by the first and the second tensioning roller.

3. The belt tensioning device of claim 1 ,
wherein the spring portion has a gradient region with an axial gradient component along at least a circumferential extension portion of the bow-shaped spring.

4. The belt tensioning device of claim 1 ,
wherein the at least one bow-shaped spring has a smaller axial length in the first and the second support portion than at least in a central region of the spring portion.

5. The belt tensioning device of claim 1 ,
wherein the spring arrangement is formed mirror-symmetrically in an axial view.

6. The belt tensioning device of claim 1 ,
wherein the bow-shaped spring is produced from a round wire or square wire.

7. The belt tensioning device of claim 1 ,
wherein the spring arrangement comprises two bow-shaped springs, which are connected to each other by at least one connection element.

8. The belt tensioning device of claim 7 ,
wherein the first support portions of the two bow-shaped springs are connected to a first support element, and that the second support portions of the two bow-shaped springs are connected to a second support element.

9. The belt tensioning device of claim 7 ,
wherein the two bow-shaped springs are formed identically and are arranged axially offset to each other.

10. The belt tensioning device of claim 7 ,
wherein the two bow-shaped springs are formed differently, wherein the first and second support portions of the two bow-shaped springs are arranged in one plane, and wherein the spring portions of the two bow-shaped springs are arranged axially offset to each other at least in a central region.

11. The belt tensioning device of claim 10 ,
wherein the two bow-shaped springs have same radii in the spring portion, and the support portions of the two bow-shaped springs have different radii.

12. The belt tensioning device of claim 1 ,
wherein at least one of the base member, the first tensioning arm and the second tensioning arm is a sheet metal part from a steel sheet.

13. The belt tensioning device of claim 12 ,
wherein the sheet thickness of at least one of the base member, the first tensioning arm and the second tensioning arm is less than a wire diameter of the bow-shaped spring, wherein the total axial length of the base member is shorter than three times a wire diameter of the bow-shaped spring.

14. The belt tensioning device of claim 1 ,
wherein pairs of support faces are formed between the base member and the first tensioning arm, between the first tensioning arm and the second tensioning arm, as well as between the second tensioning arm and the base member, wherein an annular seal is provided at least between one of the pairs of support faces.

15. The belt tensioning device of claim 14 ,
wherein one of the annular seal and one of the bearings are manufactured jointly by two-component-injection molding.

16. The belt tensioning device of claim 14 ,
wherein one of the annular seal and one of the base member, the first tensioning arm, the second tensioning arm, are connected to one another.

17. The belt tensioning device of claim 1 ,
wherein a first central bearing plane is formed by bearings supporting the tensioning rollers at the tensioning arms, and that a second central bearing plane is formed by the bearings supporting the tensioning arms on the base member,
wherein the first central bearing plane and the attachment portion for attaching the base member are arranged on different sides of the second central bearing plane, or
wherein the second central bearing plane and the attachment portion for attaching the base member are arranged on different sides of the first central bearing plane.

Assignees

• Muhr & Bender Kg

Inventors

• Pfeifer Simon
• Jud Joachim
• Schattenberg Stefan
• Rueenauver Jan

Classifications

• F16H2007/0874

  Two or more finally actuated members · CPC title

• F16H2007/0865

  Pulleys · CPC title

• F16H2007/0893

  Circular path · CPC title

• F16H7/1281 Primary

  where the axis of the pulley moves along a substantially circular path · CPC title

• F16H7/08 Primary

  Means for varying tension of belts, ropes or chains  (pulleys of adjustable construction F16H55/52) · CPC title