Belt pulley arrangment

Abstract

A belt pulley arrangement with a belt pulley that is fastenable to rotate on a shaft, a torsion spring arranged within the belt pulley for enabling a transmission of torque between the belt pulley and shaft. The torsion spring acts with one end against the shaft and with an other end against the belt pulley. A looped flat spiral spring is arranged radially between the belt pulley and the torsion spring and acting as a free-running clutch. The torsion spring is arranged on one of its axial ends in a first sleeve that is connected so that it can rotate with a radial inner lateral surface of the belt pulley. The looped flat spiral spring is arranged radially between the first sleeve and the torsion spring, and contacts, in its extended state, at least in some sections on the inner lateral surfaces of the first sleeve and belt pulley.

Claims

1. A belt pulley arrangement comprising a belt pulley that is fastenable to rotate on a shaft, a torsion spring arranged within the belt pulley that transmits torque between the belt pulley and shaft, the torsion spring having a first end that acts against the shaft and a second end that acts against the belt pulley, a looped flat spiral spring arranged radially between the belt pulley and the torsion spring that acts as a free-running clutch, the first end of the torsion spring is arranged within a first sleeve, and the first sleeve is connected to rotate with a radial inner lateral surface of the belt pulley, and the looped flat spiral spring is arranged radially between the first sleeve and the torsion spring, the looped flat spiral spring is movable to an expanded state in which, at least in some sections, the spiral spring contacts a radial inner lateral surface of the first sleeve and the radial inner lateral surface of the belt pulley.

2. The belt pulley arrangement according to claim 1, wherein the second end of the torsion spring is arranged in a second sleeve, and the second sleeve is connectable locked in rotation with the shaft.

3. The belt pulley arrangement according to claim 2, wherein a spring ramp is arranged in the first sleeve and a second spring ramp is arranged in the second sleeve, and the torsion spring is in contact with the first and second spring ramp for transmitting a torque from the belt pulley to the shaft.

4. The belt pulley arrangement according to claim 3, further comprising a driving disk that is fixable on the shaft, the driving disk has a slot extending across a partial area of a circumference thereof, and a pin of the first spring ramp engages in the slot.

5. The belt pulley arrangement according to claim 2, the second sleeve is supported on a radial outside thereof on a sliding bearing that is arranged on the radial inner lateral surface of the belt pulley.

6. The belt pulley arrangement according to claim 5, wherein the second sleeve is supported on the radial outside on a needle bearing that is arranged on the radial inner lateral surface of the belt pulley.

7. The belt pulley arrangement according to claim 6, wherein the second sleeve is connectable with the shaft by a press-fit connection.

8. The belt pulley arrangement according to claim 1, wherein the belt pulley arrangement is part of a belt drive of a motor vehicle.

9. A drive system of a motor vehicle with one main unit and at least one auxiliary unit that is connected to the main unit via a belt drive that comprises at least one belt pulley arrangement according to claim 1.

10. The drive system according to claim 9, wherein the main unit is an internal combustion engine and the auxiliary unit is an electric machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Preferred embodiments of the invention are explained in more detail below with reference to the accompanying figures. Shown are:

(2) FIG. 1 a longitudinal section view of a belt pulley arrangement according to the invention in a first embodiment;

(3) FIG. 2 a cross-sectional view of the belt pulley arrangement according to the invention along a line A-A in FIG. 1;

(4) FIG. 3 a perspective view of a driving mechanism;

(5) FIG. 4 two different perspectives of an exploded view of a driving disk and adjacent parts;

(6) FIG. 5 a perspective view of a shaft;

(7) FIG. 6 a longitudinal section view of belt pulley arrangement according to the invention in a second embodiment;

(8) FIG. 7 an exploded view of the belt pulley arrangement as per FIG. 6; and

(9) FIG. 8 a perspective view of the belt pulley arrangement as per FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) FIG. 1 shows a longitudinal section view of a belt pulley arrangement 01 according to the invention in a first embodiment. The belt pulley arrangement 01 according to the invention initially comprises a belt pulley 02, which is supported so that it can rotate on a shaft 03 by a bearing 04. A perspective view of the shaft 03 can be seen in FIG. 5. Within the belt pulley 02 there is a torsion spring 05. The torsion spring 05 is arranged on each of its two ends in a respective sleeve 07, 08. A first sleeve 07 is connected so that it can rotate with a radial inner lateral surface of the belt pulley 02. A second sleeve 08 is mounted locked in rotation on the shaft 03. A press-fit connection is advantageously used for mounting the second sleeve 08. The second sleeve 08 is supported on the radial outside on a sliding bearing 09 that is arranged on the inner lateral surface of the belt pulley 02.

(11) Within the first sleeve 07 there is a first spring ramp 10. In the second sleeve 08 there is a second spring ramp 12. The spring ramps 10, 12 are used as stops for the two ends of the torsion spring 05.

(12) Radially between the belt pulley 02 and torsion spring 05 there is a looped flat spiral spring 13 that acts as a free-running coupling device. The looped flat spiral spring 13 contacts, in some sections, on the inner lateral surfaces of the first sleeve 07 and belt pulley 07 in its expanded state. In this way, the looped flat spiral spring 13 creates a non-positive connection that transmits the torque from the belt pulley 02 to the first sleeve 07. The looped flat spiral spring 13 is designed so that torque up to a predetermined maximum value can be reliably transmitted. By use of the first sleeve 07 and looped flat spiral spring 13, the torque is transmitted via the first spring ramp 10 to the torsion spring 05. By use of the second spring ramp 12 the torque is transmitted to the second sleeve 08, which forwards the torque to the shaft 03. If the torque exceeds the maximum value, the looped flat spiral spring 13 slips.

(13) Through the overload protection integrated in this way in the belt pulley arrangement 01, the torsion spring 05 can be effectively protected from overloading, wherein its loading is reduced.

(14) The illustrated embodiment of the belt pulley arrangement 01 also has a driving mechanism that can be seen, in particular, in FIG. 2 and FIG. 3. The driving mechanism comprises a driving disk 14 that is mounted on the shaft 03 and has a slot 15 running in the circumferential direction. FIG. 4 shows two different views of an exploded view of the driving disk 14 and adjacent components (first sleeve 07, spring ramp 10, intermediate ring 21). A pin 17 of the first spring ramp 10 engages axially in the slot 15. When the belt pulley 02 is loaded in a driving direction 18, the torsion spring 05 receives the torque and moves the pin 17 in the slot 15. In contrast, if the belt pulley 02 is deflected from the shown neutral position in a free-running direction 19, the driving disk 14 moves the pin 17. By means of the pin 17, the first sleeve 07 is also moved. In this way there is no relative movement between the two spring ramps 10, 12 and thus the torsion spring 05 is also carried along.

(15) FIG. 6 shows a longitudinal section view of the belt pulley arrangement 01 according to the invention in a second embodiment. An exploded view of a belt pulley arrangement 01 constructed in this way is contained in FIG. 7, while FIG. 8 shows a perspective view of the belt pulley arrangement 01. This construction differs from that shown in FIG. 1 in that the torsion spring 05 is arranged in a first sleeve 07 on only one of its axial ends. The first sleeve 07 is connected, in turn, so that it can rotate with the radial inner lateral surface of the belt pulley 02.

LIST OF REFERENCE SYMBOLS

(16) 01 Belt pulley arrangement

(17) 02 Belt pulley

(18) 03 Shaft

(19) 04 Bearing

(20) 05 Torsion spring

(21) 06 -

(22) 07 First sleeve

(23) 08 Second sleeve

(24) 09 Sliding bearing

(25) 10 First spring ramp

(26) 11 -

(27) 12 Second spring ramp

(28) 13 Looped flat spiral spring

(29) 14 Driving disk

(30) 15 Slot

(31) 16 -

(32) 17 Pin

(33) 18 Driving direction

(34) 19 Free-running direction

(35) 20 Retaining ring

(36) 21 Intermediate ring