Roller device for a traction mechanism drive of a motor vehicle

Abstract

A roller device for a traction mechanism drive of a motor vehicle, with a roller element for introducing a torque provided via the traction mechanism and a driven shaft for driving an auxiliary unit. The roller device has a magnetic coupling for non-positive torque transfer between the roller element and the driven shaft. The magnetic coupling has a primary-side unit connected to the roller element with a primary magnetic element and a secondary-side unit connected to the driven shaft with a secondary-side magnetic element. The magnetic elements are permanent and/or electromagnetic elements. The non-positive torque transfer is realized by magnetic fields of the primary-side and secondary-side magnetic elements. At least one magnetic element of the two units for changing the magnetic field overlap of the magnetic fields of the primary-side and secondary-side magnetic elements is movably arranged within its unit. A corresponding traction mechanism drive and method are provided.

Claims

1. A roller device for a traction mechanism drive of a motor vehicle, comprising: a roller element for introducing a torque provided by the traction mechanism of the traction mechanism drive, a driven shaft for driving an auxiliary unit of the motor vehicle, and a magnetic coupling for non-positive torque transfer between the roller element and the driven shaft, the magnetic coupling includes a primary-side unit connected to the roller element with at least one primary magnetic element and a secondary-side unit connected to the driven shaft with at least one secondary-side magnetic element, the magnetic elements are at least one of permanent magnetic or electromagnetic elements and the non-positive torque transfer is realized by the magnetic fields of the primary-side and the secondary-side magnetic elements, at least one of the magnetic elements of the two units is arranged to be movable within the respective primary-side or secondary-side unit for changing a magnetic field overlap of magnetic fields of the primary-side and secondary-side magnetic elements, wherein the at least one of the magnetic elements is movable in a first direction via an adjustment force applied by an actuator device and in an opposite direction via a restoring force applied by a restoring element, the restoring force increasing an amount of overlap of the magnetic fields of the primary-side and secondary-side magnetic elements, wherein a rest position of the magnetic elements is set by an equilibrium between the adjustment force and the restoring force, and wherein the at least one of the magnetic elements that is movable has a radial displaceability or has a displaceability with at least a radial component, the respective primary-side or secondary-side unit having a guide rail for the at least one of the magnetic elements that is movable, and at least a second one of the magnetic elements is a conductor loop.

2. The roller device according to claim 1, wherein the at least one magnetic element that is movable has a displaceability with at least an axial component.

3. The roller device according to claim 1, wherein the at least one displaceable magnetic element is a permanent magnetic element.

4. The roller device according to claim 1, wherein the at least one displaceable magnetic element is an electromagnetic element.

5. The roller device according to claim 1, wherein the magnetic coupling is formed as an eddy current coupling.

6. A traction mechanism drive for driving auxiliary units of a motor vehicle with an input roller element that is connectable to an engine shaft of a motor vehicle engine, at least one output roller device coupled via a common traction mechanism to the input roller element for driving an associated auxiliary unit, and the at least one output roller device is constructed as a roller device according to claim 1.

7. A method for driving an auxiliary unit of a motor vehicle connected via a roller device according to claim 1, comprising at least one of controlling or regulating a rotational speed of the driven shaft of the roller device by displacing of the at least one displaceable magnetic element of the magnetic coupling of the roller device.

8. The roller device according to claim 1, wherein the rest position is an intermediate position between extreme positions at which one of the restoring element and the actuator have a respective maximum effect.

9. The roller device according to claim 1, wherein the restoring element is located opposite the actuator relative to the magnetic element.

10. The roller device according to claim 1, wherein the actuator applies the adjustment force in a directly radial direction.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained below using examples with reference to the accompanying drawings, wherein the features described below can be aspects of the invention both individually and also in combination. Shown are:

(2) FIG. 1 is a schematic sectional view of a roller device with a magnetic coupling according to a preferred embodiment of the invention,

(3) FIGS. 2A and 2B are diagrams for explaining the displacement of displaceable magnetic elements of the magnetic coupling,

(4) FIG. 3 is a schematic diagram of the changing overlap between the corresponding magnetic elements of the primary unit and secondary unit of the magnetic coupling,

(5) FIG. 4 is a view of a magnetic coupling formed as an eddy current coupling with primary magnetic elements that are displaceable in the radial direction in a first position,

(6) FIG. 5 is a view of a magnetic coupling formed as an eddy current coupling with primary magnetic elements that are displaceable in the radial direction in a second position,

(7) FIG. 6 is a view of a magnetic coupling with primary magnetic elements that are displaceable in the axial direction.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(8) FIG. 1 shows a roller device 10 for a traction mechanism drive of a motor vehicle in a schematic sectional view. The roller device 10 has, on the input side, a roller element 12 for introducing a torque provided via the (not shown) traction mechanism of the traction mechanism drive. The traction mechanism can be, for example, a belt, chain, etc. The roller element 12 is connected locked in rotation via an input shaft 14 with a primary-side unit 16 of a magnetic coupling 18. A secondary-side unit 20 of the magnetic coupling 18 is connected on the output side locked in rotation with a driven shaft 22 of the roller device 10. The magnetic coupling 18 is thus a coupling for non-positive torque transfer between the roller element 12 and the driven shaft 22. The driven shaft 22 is a driven shaft 22 for driving a (not shown) auxiliary unit of the motor vehicle.

(9) In each of the two units 16, 20 of the magnetic coupling 18 there is at least one magnetic element 24, 26. In the schematic diagram of FIG. 1 there are two primary magnetic elements 24 of the primary unit 16 and two secondary magnetic elements 26 of the secondary unit 20. The non-positive torque transfer is realized (at least in normal mode) via the magnetic fields of the primary-side and secondary-side magnetic elements 24, 26. The two units 16, 20 of the magnetic coupling 18 are supported so that they can rotate opposite each other within the roller device 10 and bring the primary magnetic elements 24 opposite the secondary magnetic elements 26 with respect to a plane 28 perpendicular to a common axis 30 of the shafts 14, 22.

(10) While the secondary magnetic elements 26 are arranged fixed within their unit 20, the primary magnetic elements 24 are arranged so that they are displaceable within their unit 16 for changing the magnetic field overlap of the magnetic fields of the primary-side and secondary-side magnetic elements 24, 26 within their unit 16 (double arrow 32). More precisely, these displaceable magnetic elements 24 are arranged so that they are displaceable in the radial direction within their unit 16. The displacement of the displaceable magnetic field elements leads to a change in the magnetic field overlap of the magnetic fields of the primary-side and secondary-side magnetic elements 24, 26. This causes a change in the transmitted torque. The displacement of the displaceable magnetic elements (here the primary magnetic elements 24) can vary the rotational speed 2 of the driven shaft 22 and the auxiliary unit connected to this shaft for an opposite rotational speed 1 of the roller element 12 specified by the traction mechanism drive.

(11) For displacing the displaceable magnetic field element 24, 26 or one of each of the displaceable magnetic field elements 24, 26, the corresponding unit 16, 20 has an actuator device indicated (but not shown) in FIGS. 2A and 2B. This generates an adjustment force F.sub.stell. Usually the corresponding unit 16, 20 also has a restoring element 34 acting against the actuator device for the return displacement of the at least one displaceable magnetic element 24, 26. In a simple construction, this is located on the side of the displaceable magnetic element 24, 26 opposite the actuator device and generates a restoring force F.sub.r. This situation is shown in FIG. 2A. The displacement of the magnetic element 24, 26 results from the superposition of the adjustment force and the restoring force.

(12) FIG. 2B shows a simple example of a restoring element 34. This is formed as a spring element, more precisely, a helical spring. This helical spring acts as a compression spring and is supported with its end facing away from the magnetic element on a part of the corresponding unit 16, 20 of the magnetic coupling.

(13) FIGS. 2A and 2B illustrate the principle of displacement or adjustment of displaceable magnetic elements 24, 26. One extreme position of the element 24, 26 is realized by the restoring element 34. By the use of the actuator device, the magnetic element 24, 26 can be moved or adjusted, wherein a rest position of the magnetic element 24, 26 is set by an equilibrium between the adjustment force and restoring force.

(14) In FIG. 3, different rest positions of the magnetic element 24, 26 are shown as examples. Here, the groupings at the far left and far right mark the extreme positions of the magnetic element 24, 26 at which the actuator device has a maximum effect and the restoring element 34 has maximum deflection or the actuator device is passive and the restoring element 34 is in the nominal position. For the effect of the eddy currents, the effective overlap area 36 is relevant. The greater this area is, the greater the effective torque and thus the lower the slippage between the roller element 12 and driven shaft 22.

(15) FIG. 4 shows the units 16, 20 of a magnetic coupling 18 formed as an eddy current coupling with radially displaceable primary magnetic elements 24 in a first position. The single secondary magnetic element 26 is an electromagnetic element formed as a single, closed, ring-shaped conductor loop 38. The switching state shown in FIG. 4 for the coupling 18 is ON. This means a maximum field entrainment (eddy current) of the secondary magnetic element 26 of the secondary unit 20 by the primary magnetic elements 24 of the primary unit 16. This corresponds to the state on the right side in FIG. 3. The primary magnetic elements 24 are displaceable radially outward or inward in corresponding guide rails 40. The primary and secondary units 16, 20 of the magnetic coupling 18 are separated somewhat for better clarity in the figure. One useful implementation tries to keep the axial distance between the primary and secondary units 16, 20 as small as possible. In one variant, the primary and secondary units 16, 20 can be moved toward each other or away from each other in the axial direction.

(16) FIG. 5 corresponds to the switching state OFF of the magnetic coupling 18 from FIG. 4. The magnetic elements 24 are at the maximum deflection via the mechanism described in FIGS. 2A and 2B, and there is a minimum overlap between the magnetic fields of the primary and secondary magnetic elements 24, 26.

(17) FIG. 6 shows a magnetic coupling 18 in which the magnetic elements 24, 26 of one unit 16, 20 are displaceable in the axial direction relative to the magnetic elements 26, 24 of the other unit 20, 16. The overlap of the magnetic fields of the primary and secondary magnetic elements 24, 26 can be set by an axial shift.

(18) For all of the variants it is applicable that the primary and secondary units 16, 20 can be exchanged. Likewise, the adjustment mechanism described in FIGS. 2A and 2B can be inverted, i.e., the left or right extreme position can be achieved by the restoring element 34 or the actuator device.

(19) The restoring element 34 can be any kind of mechanical (force/energy) accumulator, e.g., spring, helical spring, compression spring, tension spring, spiral spring, torsion spring, wrap spring, viscous spring, gas compression spring, air spring, elastomer spring, leaf spring, plate spring, torsion bar spring, cylindrical helical spring, conical helical spring, coil spring. Likewise, the (force/energy) accumulator can also have an electric, magnetic, electrostatic, pneumatic, hydraulic, thermal, or chemical construction.

LIST OF REFERENCE NUMBERS

(20) 10 Roller device 12 Roller element 14 Input shaft 16 Primary-side unit 18 Magnetic coupling 20 Secondary-side unit 22 Driven shaft 24 Primary magnetic element 26 Secondary magnetic element 28 Plane 30 Axis 32 Double arrow 34 Restoring element 36 Overlap area 38 Conductor loop 40 Guide rail