Tensioning device for tensioning a helical spring

Abstract

The invention relates to a tensioning device (01) for tensioning a coil spring (02) that is supported on a main shaft (03) and at a fixed end is rotatably fixedly connected to a frame. The tensioning device (01) includes a gear drive (05), having a first gear element (06) that is axially displaceably guided on the main shaft (03) and rotatably fixedly connected to a free end of the coil spring (02), and having a second gear element (07) that is in drive engagement with the first gear element (06) in order to set the first gear element (06) in rotation about the main shaft (03). The tensioning device (01) also includes a retaining element (19) that holds the second gear element (11) in the position of drive engagement with the first gear element (06). Furthermore, the tensioning device (01) includes a drive element that is coupled to the second gear element (12) in order to set it in rotation. The gear drive is formed as a bevel gear transmission, wherein the first gear element (06) is formed as a bevel gear (06) and the second gear element (07) is formed as a bevel gear pinion (07), and wherein the rotational axes of the two gear elements (06, 07) extend perpendicularly to one another. The bevel gear (06) is integrally connected to a guide bushing (10), and has a central opening (09) through which the main shaft (03) extends, and has a cylindrical receiving section (12) in which the free end of the coil spring (02) is fastened.

Claims

1. A tensioning device for tensioning a coil spring that is supported on a main shaft and at a fixed end is rotatably fixedly connected to a frame or housing part, the tensioning device comprising: a gear drive having a first gear element that is axially displaceably guided on the main shaft and rotatably fixedly connected to a free end of the coil spring, and having a second gear element that is in drive engagement with the first gear element in order to set the first gear element in rotation about the main shaft; a retaining element that holds the second gear element in the position of drive engagement with the first gear element; a drive element that is coupled to the second gear element in order to set the second gear element in rotation; wherein the gear drive is formed as a bevel gear transmission, wherein the first gear element is formed as a bevel gear and the second gear element is formed as a bevel gear pinion, and wherein the rotational axes of the two gear elements extend perpendicularly to one another; the bevel gear is integrally connected to a guide bushing that is axially displaceably guided on the main shaft, and on an outer circumference of the guide bushing is a guide groove in which an axially central guide pin of the bevel gear pinion is supported, wherein the guide pin is rotatably fixedly connected to the bevel gear pinion; the bevel gear has a central opening through which the main shaft extends, and has a cylindrical receiving section on the side facing axially away from the guide bushing, in which the free end of the coil spring is fastened; the retaining element includes a bracket and a pressure plate connected thereto, wherein the bracket engages around the guide bushing and the bevel gear pinion, and wherein the pressure plate is positioned to apply a retaining force to the base surface of the bevel gear pinion in the axial direction, so that the guide pin is pressed into the guide groove.

2. The tensioning device according to claim 1, wherein the drive element is formed by an electric motor, on the motor axis of which the second gear element is mounted.

3. The tensioning device according to claim 1, wherein it also includes a fixing element with which the first gear element may be nonrotatably fixed to the main shaft.

4. The tensioning device according to claim 1, wherein the second gear element is detachably mounted so that the drive engagement may be discontinued.

5. The tensioning device according to claim 4, wherein the bracket and the pressure plate are detachably mounted in order to release the second gear element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantages, particulars, and refinements of the invention result from the following description of one preferred embodiment, with reference to the drawings, which show the following:

(2) FIG. 1 shows a side view of a tensioning device according to the invention for tensioning a coil spring;

(3) FIG. 2 shows a front view of the tensioning device together with a retaining element.

DETAILED DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows a side view of a tensioning device 01 according to the invention for tensioning a coil spring 02 that is guided on a main shaft 03. The area in which the coil spring 02 at a fixed end is rotatably fixedly connected to a housing part or a frame (not shown) is not illustrated.

(5) The tensioning device includes a gear drive that is formed by a first gear element 06 and a second gear element 07, the first gear element 06 being designed as a bevel gear and the second gear element 07 being designed as a bevel gear pinion. The rotational axis of the bevel gear 06 extends perpendicularly with respect to the rotational axis of the bevel gear pinion 07.

(6) The bevel gear 06 is axially displaceably guided on the main shaft 03. For this purpose, the bevel gear 06 has a first axial through opening 09 through which the main shaft 03 extends.

(7) The bevel gear 06 on its side facing away from the coil spring 02 is connected to a guide bushing 10. The guide bushing 10 is preferably integrally formed on the bevel gear and has a guide groove 11. The guide groove 11 has a radially circumferential design. The side of the bevel gear 06 directed toward the coil spring has a cylindrical receiving section 12. The through opening 09 continues in the guide bushing 10 and in the receiving section 12.

(8) One end of the coil spring 02 that is rotatable with respect to the main shaft 03 during the tensioning operation is fastened to the receiving section 12, so that a torque is transmitted into the coil spring 02 when the first gear element 06 rotates. The applied torque results in tensioning or relaxing of the coil spring, depending on the rotational direction of the first gear element 06.

(9) The bevel gear pinion 07 has a second axial through opening 14. The second through opening 14 is used to accommodate a drive shaft 15 that is designed to be connectable at one end to an electric drive (not illustrated), and whose free end is designed as a guide pin 16. The drive shaft 15 is rotatably fixedly connected to the bevel gear pinion 07, and transmits a torque from the electric drive to the bevel gear pinion 07. For guiding the bevel gear pinion 07, the guide pin 16 of the bevel gear pinion 07 is situated in the guide groove 11, in engagement with the bevel gear 06. Alternatively, the bevel gear pinion, the drive shaft, and the guide pin may have an integral design.

(10) FIG. 1 also shows a first counterpiece 17 that is situated on the guide bushing 10 and has an inwardly directed section that engages with the guide groove 11. The contact surfaces of the counterpiece 17 are large enough to form sufficiently large contact areas between a retaining element 19 (FIG. 2) and the guide bushing 10.

(11) FIG. 2 shows a front view of the tensioning device 01 together with the retaining element 19. The retaining element 19 includes a bracket 20 and a pressure plate 21. The bracket 20 engages around the guide bushing 10 and the bevel gear pinion 07. The pressure plate 21 is situated on the base surface of the bevel gear pinion 07. The bracket 20 and the pressure plate 21 are preferably detachably mounted in order to release the bevel gear pinion 07. As a result of the retaining element 19, the bevel gear 06 remains in drive engagement with the bevel gear pinion 07, in particular when the position of the bevel gear 06 along the main shaft 03 changes between a tensioned and a relaxed position.

(12) The drive engagement between the bevel gear 06 and the bevel gear pinion 07 may be discontinued as soon as the retaining element 19 is detached and thus, no retaining force acts on the bevel gear pinion 07 and the guide bushing 10 of the bevel gear 06. The detachable connection may be formed by screws, for example.

(13) FIG. 2 also shows the drive axle 15 that extends through the second through opening 14 in the bevel gear pinion 07 and is guided in the guide groove 11. The drive shaft 15 is designed as a guide pin 16 at the end of the drive shaft 15 that is situated in the guide groove 11.

(14) Furthermore, FIG. 2 shows that a second counterpiece 23 is provided in addition to the first counterpiece 17. The two counterpieces 17, 23 are axially spaced apart with respect to the drive axle 15 and oppositely situated, the second counterpiece 23 being situated between the base surface of the bevel gear pinion 07 and the pressure plate 21 of the retaining element 19. The contact surfaces of the second counterpiece 23 are large enough to form sufficiently large contact areas between the retaining element 19, in particular the pressure plate 21, and the base surface of the bevel gear pinion 07.