Source: http://www.google.com/patents/US7325663
Timestamp: 2014-07-29 01:32:44
Document Index: 302994450

Matched Legal Cases: ['art.\n7', 'art.\n8', 'art 1', 'art 2', 'art 8', 'art 2', 'art 2', 'art 8', 'art 8', 'art 2', 'art 8']

Patent US7325663 - Magnetorheologic clutch - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA magnetorheological clutch comprises a stationary part (1), of a rotatable primary part (2) with primary lamellae (3) and of a secondary part (8) with secondary lamellae (17) which surrounds the primary part (2), there being formed between the primary part (2) and the secondary part (8) a space (28)...http://www.google.com/patents/US7325663?utm_source=gb-gplus-sharePatent US7325663 - Magnetorheologic clutchAdvanced Patent SearchPublication numberUS7325663 B2Publication typeGrantApplication numberUS 10/532,379PCT numberPCT/AT2003/000328Publication dateFeb 5, 2008Filing dateOct 31, 2003Priority dateOct 31, 2002Fee statusLapsedAlso published asCA2508568A1, DE50308513D1, EP1595086A1, EP1595086B1, US7461731, US20050252744, US20080142328, WO2004040157A1Publication number10532379, 532379, PCT/2003/328, PCT/AT/2003/000328, PCT/AT/2003/00328, PCT/AT/3/000328, PCT/AT/3/00328, PCT/AT2003/000328, PCT/AT2003/00328, PCT/AT2003000328, PCT/AT200300328, PCT/AT3/000328, PCT/AT3/00328, PCT/AT3000328, PCT/AT300328, US 7325663 B2, US 7325663B2, US-B2-7325663, US7325663 B2, US7325663B2InventorsHerbert SteinwenderOriginal AssigneeMagna Drivetrain Ag &Co KgExport CitationBiBTeX, EndNote, RefManPatent Citations (7), Referenced by (1), Classifications (7), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetMagnetorheologic clutchUS 7325663 B2Abstract A magnetorheological clutch comprises a stationary part (1), of a rotatable primary part (2) with primary lamellae (3) and of a secondary part (8) with secondary lamellae (17) which surrounds the primary part (2), there being formed between the primary part (2) and the secondary part (8) a space (28) which contains a magnetorheological fluid, a regulatable magnetic field acting on the magnetorheological fluid. In order to have as small a build as possible, to be capable of transmitting a maximum torque with minimum current and to be easily controllable, at least one magnet coil (21) is arranged in front of or behind the lamellae (4, 17) in the axial direction and loops around a first U-shaped yoke (20), the two end faces (26) of which are on the same side of the lamellae and parallel to these, at least one second yoke (22) is on the side of the lamellae which faces away from the first yoke (20), and the regions of the secondary part (8) which lie inside and outside the lamellae (4, 17) in the radial direction consist of a material of low magnetic permeability.
a stationary part, of a rotatable primary part with primary lamellae and a secondary part with secondary lamellae which is rotatable about a common axis and surrounds the primary part, so as to define between the primary part and the secondary part a space which contains a magnetorheological fluid and in which the primary lamellae and secondary lamellae alternate in the axial direction, and a regulatable magnetic field acting on the magnetorheological fluid, wherein a) at least one magnet coil is arranged in front of or behind the lamellae in the axial direction and loops around a first U-shaped yoke having two end faces adjacent to and parallel to the lamellae, b) at least one second yoke is provided on the side of the lamellae which faces away from the first yoke, and c) the regions of the secondary part which lie inside and outside the lamellae in the radial direction consist of a material of low magnetic permeability.
2. The magnetorheological clutch as claimed in claim 1, wherein the cross section of the first U-shaped yoke is increased toward the end face.
3. The magnetorheological clutch as claimed in claim 1, wherein the second yoke is a flat body running in the circumferential direction and is surrounded by no magnet coil.
4. The magnetorheological clutch as claimed in claim 1, wherein the second yoke is also of U-shaped design and is surrounded by a magnet coil.
5. The magnetorheological clutch as claimed in claim 1, wherein the first U-shaped yoke is connected to the secondary part and the end faces of the first yoke form the boundary wall of the space containing the magnetorheological fluid.
6. The magnetorheological clutch as claimed in claim 1, wherein the first U-shaped yoke is connected to the stationary part and is adjacent to an annular region of high permeability of the secondary part.
7. The magnetorheological clutch as claimed in claim 6, wherein the at least one second yoke is also connected to the stationary part and is adjacent to an annular region of high permeability of the secondary part.
8. The magnetorheological clutch as claimed in claim 6, wherein the second yoke is designed without a specific magnet coil in the secondary part otherwise consisting of a material of low permeability.
9. The magnetorheological clutch as claimed in claim 1, wherein a number of yokes and magnet coils are provided, their axes lying tangentially in an axially normal plane.
10. The magnetorheological clutch as claimed in claim 9, wherein the end faces of the yokes are widened to form annular sectors which almost adjoin one another and the inner and outer radius of which corresponds essentially to that of the lamellae.
11. The magnetorheological clutch as claimed in claim 10, wherein an even number of magnet coils succeed one another in a polarity such that adjacent legs of their U-shaped yokes form a common annular sector as an end face.
12. A magnetorheological clutch comprising:
a primary rotatable member and a secondary rotatable member forming a clutch cavity;
a magnetorheological fluid disposed in the clutch cavity; and
at least one coil assembly selectively operable to generate a magnetic field in the clutch cavity, the magnetic field having a first polarity in a first direction and a second polarity in a second direction different than the first direction.
13. The magnetorheological clutch of claim 12, wherein the at least one coil assembly includes a magnet coil supported by a yoke having a first end face and second end face, wherein and first end face is polarized in the first direction and the second end face is polarized in the second direction.
14. The magnetorheological clutch of claim 13, wherein the primary and secondary members have a common axis of rotation and the magnet coil has a center axis obliquely orientated relative to the axis of rotation.
15. The magnetorheological clutch of claim 14, wherein the clutch cavity includes an outer diameter and the magnet coil is disposed adjacent to the clutch cavity and radially inboard of the outer diameter.
16. The magnetorheological clutch of claim 12, wherein the at least one coil assembly comprises a plurality of coil assemblies.
17. The magnetorheological clutch of claim 16, wherein the plurality of coil assemblies generate a plurality of first polarities in a first direction and a plurality of second polarities in a second direction.
18. A magnetorheological clutch comprising:
a primary rotatable member and a secondary rotatable member, the primary and secondary members having a common axis of rotation and forming a clutch cavity having axial ends and an outer diameter; and
at least one coil assembly disposed adjacent to one of the axial ends and radially inboard of the outer diameter, the at least one coil assembly including a magnet coil having a center axis noncoincident to the axis of rotation.
19. The magnetorheological clutch of claim 18, wherein the at least one coil assembly further includes a yoke supporting the magnet coil, the yoke having a plurality of end faces disposed adjacent to the clutch cavity and radially inboard relative the outer diameter.
20. The magnetorheological clutch of claim 18, wherein the at least one coil assembly comprises a plurality of coil assemblies, wherein a first coil assembly is disposed adjacent to a first axial end of the clutch cavity and a second coil assembly is disposed adjacent to a second axial end of the clutch cavity.
BACKGROUND OF THE INVENTION This application is a National Stage of International Application No. PCT/AT2003/000328, filed Oct. 31, 2003 which claims the benefit of GM 739/2002, filed Oct. 31, 2002. The disclosures of the above applications are incorporated herein by reference.
The invention relates to magnetorheological clutches which consist of a stationary part, of a rotatable primary part with primary lamellae and of a secondary part with secondary lamellae which is rotatable about a common axis and surrounds the primary part, there being formed between the primary part and the secondary part a space which contains a magnetorheological fluid and in which primary lamellae and secondary lamellae alternate in the axial direction, and a magnet coil generating a magnetic field of regulatable field strength which acts on the magnetorheological fluid.
However, for the use of a generic clutch in the drive train of a motor vehicle, current consumption and overall size are critical and must therefore be minimized. In addition to this, there are also further requirements: such a wide regulating range of the transmitted torque that, on the one hand, slip-free starting from standstill and, on the other hand, (also) for reasons of noise, complete separation are possible; and, finally, a rapid response in order to be compatible with electronic drive dynamics controls (ESB, ABS, etc.).
The object of the invention is, therefore, to provide a magnetorheological clutch which avoids the disadvantages of the prior art and satisfies the above-specified requirements of the modern motor vehicle. It is to have as small a build as possible, particularly in diameter, is to be capable of transmitting a maximum torque with minimum current consumption and is to be easily controllable.
SUMMARY OF THE INVENTION According to the invention, at least one magnet coil is arranged in front of or behind the lamellae in the axial direction, that is to say approximately on the same radius as these, said magnet coil looping around a first U-shaped yoke, the two end faces of which are on the same side of the lamellae and parallel to these and are largely adjacent to the lamellae, at least one second yoke is provided on the side of the lamellae which faces away from the first yoke, and the regions of the secondary part which lie inside and outside the lamellae in the radial direction consist of a material of low magnetic permeability.
The magnet coils lie in front of and behind the lamellae, and therefore the outside diameter of the clutch is determined by the diameter of the lamellae. The second yokes arranged on the other side of the bundle of lamellae close the magnetic field lines, so that the magnetic field lines, already short per se, pass twice through the bundle of lamellae, that is to say are �double-acting�. With the corresponding arrangement of the magnet coils, the field is highly dense and uniform over the entire area of the bundle of lamellae. The parts of the secondary part which consist of a material of low magnetic permeability prevent a dispersion of the magnetic field.
In an advantageous embodiment of the invention, the at least one first U-shaped yoke is connected to the secondary part and the end face of the first yoke forms the boundary wall of the space containing the magnetorheological fluid. The magnet coils thus rotate together with the secondary part. This avoids the need for any air gap, which means a minimization of the magnetic losses. The second yoke then likewise rotates together with the secondary part, irrespective of whether it is designed to be U-shaped with a magnet coil or to be flat and without a magnet coil. In this case, an electrical brush connection is necessary for supplying the electrical current to the magnet coils.
In an alternative advantageous embodiment of the invention, the first U-shaped yokes are connected to the stationary part and their end faces are adjacent to an annular region of the secondary part, the permeability of which region is high, in contrast to the majority of the secondary part (claim 6). There is therefore no need for a brush connection, at the expense of an air gap which, however, can be kept very small by virtue of the arrangement according to the invention. The second yokes may be designed likewise.
BRIEF DESCRIPTION OF THE DRAWINGS The invention is described and explained below with reference to drawings in which:
FIG. 2 a shows a section according to II-II, developed in order to illustrate the magnetic field lines,
DETAILED DESCRIPTION Of the stationary part 1, FIG. 1 depicts only the collar which makes the brush contact for supplying the electrical current to the magnet coils. Torque transmission in the clutch takes place between a primary part 2 and a secondary part 8. The primary part 2 is seated fixedly in terms of rotation on a primary shaft 3 and forms a drum 5 with coupling teeth for the rotationally fixed, but displaceable reception of the primary lamellae 4. The primary part 2 itself consists of a material of very low magnetic permeability, and the primary lamellae 4 consist of a material of high magnetic permeability.
The secondary part 8 is screwed to the connecting flange 9 of a secondary shaft and receives the primary shaft 3 in bearings 10, 11. The secondary part 8 and primary part 2 are coaxial. The secondary part 8 consists of a front cover 12, of a rear cover 13 and of a circumferential wall 14 which on one side is welded to the front cover 12 and on the other side is connected to the rear cover 13 by means of an annular nut 15. The circumferential wall 14 has on the inside a coupling toothing 16, in which the secondary lamellae 17 are arranged fixedly in terms of rotation, but displaceably.
FIGS. 2 a and 2 b illustrates, developed, a cylindrical section through the yokes 20, 22 according to II-II (FIG. 2 a) and, above it, the magnetic field strengths (FIG. 2 b). This section illustrates only the parts in which the magnetic field lines run and therefore those which consist of a material of high magnetic permeability. These are the yokes 20, 22 and the alternating lamellae 4, 17. What can be seen are the U-shape of the yokes 20, 22 with legs 20′, 20″ and legs 22′, 22″, respectively, and a thick closed curve 34 which indicates the direction and polarity of the magnetic field (counterclockwise). In the adjacent region on the left in the figure, the field direction 35 is clockwise, that is to say opposite to that of the yokes 20, 22. A plurality of field lines are also indicated here, so that a zone 36 in which the field strength has a zero crossing can be seen.
Overall, in all the variants described, with a given current intensity, a maximum magnetic field strength is afforded over the entire clutch space, matching to practical requirements being possible by the choice of one of the many variants described or their combinations. In all instances, because of the arrangement of the magnet coils in front of and behind the lamellae of the clutch (and not inside or outside the latter), the construction space in the radial direction is also relatively small. This is particularly advantageous for use in the drive train of a motor vehicle.
Patent CitationsCited PatentFiling datePublication dateApplicantTitleUS2685947Jun 17, 1950Aug 10, 1954Vickers IncClutch or brake employing magnetic particlesUS2983349 *Oct 17, 1957May 9, 1961Gen ElectricMagnetic clutchUS5823309 *May 23, 1997Oct 20, 1998General Motors CorporationMagnetorheological transmission clutchUS5845753Mar 16, 1998Dec 8, 1998New Venture Gear, Inc.Torque transfer apparatus using magnetorheological fluidsUS5896965 *Jun 2, 1997Apr 27, 1999General Motors CorporationMagnetorheological fluid fan clutchUS5967273 *Oct 17, 1997Oct 19, 1999Eaton CorporationMagneto-rheological fluid couplingUS6183386 *Dec 27, 1996Feb 6, 2001Dana CorporationDifferential containing rheological fluid* Cited by examinerReferenced byCiting PatentFiling datePublication dateApplicantTitleUS7461731 *Feb 4, 2008Dec 9, 2008Magna Drivetrain Ag & Co KgMagnetorheologic clutch* Cited by examinerClassifications U.S. Classification192/21.5, 192/58.41International ClassificationF16D37/02, F16D35/00Cooperative ClassificationF16D37/02, F16D2037/007European ClassificationF16D37/02Legal EventsDateCodeEventDescriptionMar 27, 2012FPExpired due to failure to pay maintenance feeEffective date: 20120205Feb 5, 2012LAPSLapse for failure to pay maintenance feesSep 12, 2011REMIMaintenance fee reminder mailedApr 21, 2005ASAssignmentOwner name: MAGNA DRIVETRAIN AG & CO. KG, AUSTRIAFree format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:STEINWENDER, HERBERT;REEL/FRAME:016932/0579Effective date: 20050330RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google