Eddy current apparatus and method of operation of this apparatus

Abstract

The invention relates to an eddy current device comprising a stator and a rotor. The stator includes an annular support (14) provided with pole cores (16), inductor coils arranged around the pole cores, and pole flares (22) fixed to one end of each pole core. The rotor includes at least one induced cylindrical portion located opposite the pole flares. The stator includes a wedge (20) arranged between a pole core (16) and a pole flare (22). Figure to be published with the abbreviation: Figure 5

Description

Title of the invention: Eddy current apparatus and method of operation of this apparatus Technical field of the invention

[0001] The present invention relates to an eddy current device, in particular an electromagnetic retarder and a method of operating this device. Prior art

[0002] It has been observed that the rotors deform over time. In particular, the inner diameter of the rotors narrows or widens after a certain number of operating cycles, and then stabilizes after a greater number of operating cycles. This plastic deformation results from rotor heating. A decrease in the rotors' inner diameter creates a risk of collision between the rotor and the stator, which can lead to irreversible damage to the retarder. An increase in the rotors' diameter also results in an irreversible degradation of the retarder's performance. Presentation of the invention

[0003] One object of the present invention is to avoid a degradation of the retarder and its performance generated by this deformation of the rotor. Summary of the invention

[0004] The present invention relates to an eddy current device comprising a stator and a rotor adapted to pivot relative to the stator around an axis of rotation, the stator comprising: - an annular support provided with polar cores, the polar cores having respective axes perpendicular to the axis of rotation, the polar cores being distributed at regular intervals along a circle centered on a center of the axis of rotation, - inductor coils arranged around the polar cores, and - polar expansions fixed each at one end of each polar core; and the rotor comprising at least one induced cylindrical portion located opposite the polar flares, characterized in that the stator further comprises at least one wedge, at least a part of said wedge being arranged between at least one polar core and at least one polar flare.

[0005] The features described in the following paragraphs may optionally be implemented. They may be implemented independently of each other or in combination with each other: - the wedge has the shape of a strip. - the wedge has a thickness between 0.5 millimeter and 1.5 millimeter, and preferably 1 millimeter. - The eddy current apparatus further comprises at least one washer mounted around at least one pole core; said at least one washer being interposed between at least one inductor coil and at least one pole flare. - The eddy current device further comprises at least one thermal protection plate having a through hole and an edge inclined towards the inductor coil; said at least one thermal protection plate is arranged around a pole core. - At least part of the at least one wedge is interposed between said at least one thermal protection plate and the polar flare. - At least one wedge has a cross-section with a surface area at least 30% greater than the surface area of ​​a cross-section of a polar core; said cross-sections being perpendicular to an axis of at least one polar core. - Said at least one thermal protection plate is arranged between at least one washer and a polar flare. - At least one wedge has a cross-section with a dimension substantially equal to the dimension of a cross-section of a polar core; said cross-sections being perpendicular to an axis of at least one polar core. -Said at least one washer is made of a compressible material, for example silicone, spring steel or rubber.

[0006] The invention also relates to a method of operating an eddy current device mounted on a vehicle's drive shaft, the eddy current device comprising a stator and a rotor adapted to pivot relative to the stator about an axis of rotation, the stator having an annular support provided with pole cores, inductor coils arranged around the pole cores, and pole flares fixed to one end of each pole core and at least one shim, at least a portion of said shim being arranged between at least one pole core and at least one pole flare; and the rotor having at least one induced cylindrical portion located opposite the pole flares, the method comprising the following steps: - operation of the eddy current device during a number of operating cycles; - Disassembly of the rotor from the vehicle's drive shaft - Removal of the polar flanges and stator shims, - fixing the polar flares onto the polar cores without the shims, - reassembling the rotor onto the transmission shaft of a vehicle, - operation of the eddy current device. Brief description of the figures

[0007] [Fig. 1] is a schematic perspective view of the rotor of an eddy current device according to the present invention;

[0008] [Fig.2] is a schematic perspective view of the stator of an eddy current device according to the present invention;

[0009] [Fig.3] is a schematic perspective view of an eddy current apparatus according to the present invention;

[0010] [Fig.4] is a perspective view of the stator body;

[0011] [Fig.5] is a perspective view of part of a stator without an inductor coil of an eddy current device according to a first embodiment of the invention;

[0012] [Fig.6] is a cross-sectional view of part of a stator of an eddy current device according to a second embodiment of the invention;

[0013] [Fig.7] is a cross-sectional view of part of a stator of an eddy current device according to a third embodiment of the invention;

[0014] [Fig.8] is a diagram representing the steps of the operating process of the eddy current device according to the invention. Detailed description of the invention

[0015] The eddy current device 2 according to the invention is described below in its preferred, but not limiting, application to an eddy current retarder.

[0016] The eddy current device 2 comprises a rotor 4 and a stator 6. The rotor is fixed by means of an intermediate piece to a transmission shaft of a vehicle equipped with a retarder. The rotor 4 comprises an induced cylindrical portion 8, a hub 10, and angled arms 12 that connect the induced cylindrical portion to the hub. The hub is adapted to pivot about an axis of rotation XX.

[0017] The stator 6 includes an annular support 14 fixed by suitable means to the vehicle chassis or to the vehicle's gearbox housing. The axis of the annular support 14 is coaxial with the axis of rotation XX. With reference to Figures 2 and 4, the support 14 is provided with peripheral pole pieces 16.

[0018] The polar cores 16 are distributed at regular intervals along a circle C centered on a center O of the axis of rotation X. The polar cores have respective axes Y perpendicular to the axis of rotation XX.

[0019] The stator 6 comprises inductor coils 18 arranged around the pole cores. Each inductor coil 18 comprises a conducting wire wound around a pole core. The winding directions of the conducting wire alternate from one inductor coil to the next along the circle C, so as to alternate the polarities of the inductors. conductors. Each inductor coil 18 is traversed by a polar core with axis Y.

[0020] The stator 6 further comprises at least one shim 20 and a polar flare 22 fixed to each polar core by at least one fixing screw 24. The shim 20 and the polar flare 22 are fixed to one end of each polar core 16 by at least one fixing screw 24.

[0021] In the first embodiment shown in [Fig.5], the wedge 20 and the polar flare 22 are provided with two through holes 26, 28. Each polar core 16 is also provided with two tapped holes 30 having an axis parallel to the Y axis. Two fixing screws 24 pass through the holes 26 of the wedge and the holes 28 of the polar flare and are fixed in the tapped holes 30 of the polar core.

[0022] In the first embodiment, the wedge 20 is arranged between a polar core 16 and a polar flare 22.

[0023] The wedge 20 has the shape of a slat. In particular, the wedge 20 has the shape of a flat rectangular parallelepiped.

[0024] The shim 20 has a thickness of between 0.5 millimeters and 1.5 millimeters. Preferably, the shim has a thickness of 1 millimeter. The shim is made of a current-conducting material such as, for example, low-carbon magnetic steel.

[0025] A thin air gap E is provided between the polar flare 22 and the induced cylindrical portion 8 of the rotor. This air gap E is traversed by a magnetic flux when the rotor passes in front of the polar flare 22.

[0026] The polar flare 22 serves to immobilize the inductor coil 18 with respect to the polar core 16.

[0027] The shims 20 compensate for the potential rotor deformation caused by a number of idle speed operations. For this purpose, the shims can be removed or added to restore the initial size of the air gap between the rotor and the pole piece. After a certain number of operating cycles, the stator deforms. Once the stator has deformed, an operator can disassemble the rotor to access the stator. The operator can then unscrew the retaining screws 24, remove the shims 20, and reattach the pole pieces 22 to the pole cores 16 using the retaining screws 24. Figure 6 shows a side view of part of an eddy current apparatus 32 according to a second embodiment. The eddy current apparatus according to this second embodiment is similar to the eddy current apparatus according to the first embodiment and will not be described in full a second time. The technical elements of the eddy current apparatus of the second embodiment are identical to the technical elements of the eddy current apparatus of the first embodiment and have the same reference numerals and will not be repeated. Redrawn. Only the different technical elements will be described.

[0028] In this second embodiment, the stator 6 further comprises at least one washer 34 mounted around each pole core 16 and at least one thermal protection plate 36 arranged around each pole core 16.

[0029] The washer 34 is interposed between the inductor coil 18 and the polar flare 22. Preferably, the washer 34 is made of a compressible material such as, for example, silicone, spring steel, or rubber. The washer is compressed during assembly to compensate for tolerances in the stacking of the parts and to exert some compression on the inductor coil to hold it on the annular support 14.

[0030] Each thermal protection plate 36 is arranged between the washer 34 and the polar flare 22. The thermal protection plate 36 is in contact with an internal main face of the polar flare 22.

[0031] Each thermal protection plate 36 is provided with a central opening 38 and an edge 40 inclined towards the inductor coil.

[0032] The protective plates 36 are for example made of a non-magnetic stainless steel material or of glass fibers.

[0033] In this embodiment, the wedges 37 have a particular dimension. In this second embodiment, the wedges 37 have a cross-section with a dimension substantially equal to the dimension of a cross-section of a polar core 16. The cross-section of the wedges and the cross-section of the polar core considered here are sections along planes perpendicular to each Y axis of each polar core 16. When the wedges are placed on the polar cores 16, they increase the height of the polar cores.

[0034] As shown in [Fig. 6], the thermal protection plate 36 is positioned next to the shim 37. The upper face of the thermal protection plate 36 is at the same distance from the center O as the upper face of the shim 37. When the shim 37 is removed, the washer 34 is more compressed than when the shim 37 is present. Thus, when the shim is removed, the washer is compressed so that the upper face of the thermal protection plate is at the same distance from the center O as the upper face of the polar core.

[0035] Figure 7 shows a side view of part of an eddy current apparatus 42 according to a third embodiment. The eddy current apparatus according to this third embodiment is similar to the eddy current apparatus according to the first and second embodiments.

[0036] The eddy current apparatus according to this third embodiment will not be described in full a second time. The technical elements of the eddy current apparatus of the third embodiment are identical to the technical elements of The eddy current apparatus of the first embodiment and the second embodiment have the same reference numbers and will not be described again. Only the different technical elements will be described.

[0037] In this third embodiment, the stator 6 further comprises at least one washer 34 mounted around each pole core 16 and at least one thermal protection plate 36 also mounted around each pole core 16.

[0038] With reference to [Fig.7], the wedge 44 of this third embodiment has a dimension greater than the dimension of a polar core 16. Part of the wedge 44 rests on part of the thermal protection plate 36.

[0039] In particular, the wedge 44 has a cross-section having a surface area at least 30% greater than the surface area of ​​a cross-section of a polar core 16. The cross-sections being made along planes perpendicular to the axes of the polar cores.

[0040] Part of the thermal protection plate 36 is arranged between the washer 34 and a polar flare 22.

[0041] In this embodiment, the washer 34 is compressed during assembly in order to compensate for the tolerances of the stacking of the parts and to hold the inductor coil 18 against the annular support 14.

[0042] Alternatively, wedge 20 is replaced by several wedges. The invention also relates to a method of operating an eddy current device mounted on a vehicle's drive shaft. The eddy current device is a device shaped according to the characteristics of the devices in the first, second, or third embodiments described above. With reference to [Fig.8], the process comprises the following steps: - operation 46 of the eddy current device during a number of operating cycles; - Disassembly 48 of the rotor in relation to the transmission shaft of a vehicle - 50% removal of the polar expansion joints and stator wedges, - fixing 52 of the polar expansions onto the polar cores without the wedges, - reassembly 54 of the rotor onto the transmission shaft of a vehicle, - operation 56 of the eddy current device.

Claims

Claims

1. Eddy current apparatus (2, 32, 42) comprising a stator (6), and a rotor (4) capable of pivoting relative to the stator about an axis of rotation (XX), the stator (6) comprising: - an annular support (14) provided with polar cores (16), the polar cores (16) having respective axes (Y) perpendicular to the axis of rotation (XX), the polar cores being distributed at regular intervals along a circle (C) centered on a center (0) of the axis of rotation (X), - inductor coils (18) arranged around the polar cores, and - polar shoes (22) each fixed to one end of each polar core;and the rotor (4) comprising at least one induced cylindrical portion (8) located opposite the polar expansions (22), characterized in that the stator further comprises at least one shim (20, 37, 44), at least a part of said shim (20, 37, 44) being arranged between at least one polar core (16) and at least one polar expansion (22).;

2. An eddy current apparatus (2, 32, 42) according to claim 1, wherein the shim (20, 37, 44) has the shape of a lamella.

3. Eddy current apparatus (2, 32, 42) according to any one of claims 1 and 2, wherein the shim (20, 37, 44) has a thickness of between 0.5 millimeters and 1.5 millimeters, and preferably 1 millimeter.

4. An eddy current apparatus (32, 42) according to any one of claims 1 to 3, which further comprises at least one washer (34) mounted around at least one pole core (16); said at least one washer (34) being interposed between at least one inductor coil (18) and at least one pole shoe (22).

5. An eddy current apparatus (32, 42) according to any one of claims 1 to 4, which further comprises at least one thermal protection plate (36) provided with a through hole (38) and an edge (40) inclined towards the inductor coil; said at least one thermal protection plate (36) is arranged around a pole core (16).

6. An eddy current apparatus (42) according to the combination of claims 4 and 5, wherein at least a portion of the at least one shim (44) is interposed between said at least one protective plate thermal (36) and polar expansion (22).

7. An eddy current apparatus (42) according to claim 6, wherein the at least one shim (44) has a section having a surface area at least 30% greater than the surface area of a section of a pole core (16); said sections being perpendicular to an axis (Y) of at least one pole core (16).

8. The eddy current apparatus (32) of claim 5, wherein said at least one thermal protection plate (36) is arranged between the at least one washer (34) and a pole shoe (22).

9. Eddy current apparatus (32) according to claim 6, wherein the at least one shim (37) has a section having a dimension substantially equal to the dimension of a section of a polar core (16); said sections being perpendicular to an axis (Y) of at least one polar core (16).

10. An eddy current apparatus (2, 32) according to any one of claims 4 to 9, wherein said at least one washer (34) is made of a compressible material, for example silicone, spring steel or rubber.

11. A method of operating an eddy current apparatus mounted on a transmission shaft of a vehicle, the eddy current apparatus (2, 32, 42) comprising a stator (6), and a rotor (4) capable of pivoting relative to the stator about an axis of rotation (XX), the stator (6) comprising an annular support (14) provided with polar cores (16), inductor coils (18) arranged around the polar cores, and polar shoes (22) each fixed to one end of each polar core and at least one shim, at least a portion of said at least one shim (20, 37, 44) being arranged between at least one polar core (16) and at least one polar shoe (22); and the rotor (4) comprising at least one induced cylindrical portion (8) located opposite the pole shoes (22), the method comprising the following steps: - operation (46) of the eddy current device during a number of operating cycles;- disassembly (48) of the rotor relative to the transmission shaft of a vehicle - removal (50) of the pole shoes and the shims from the stator, - fixing (52) of the pole shoes on the pole cores without; the wedges, - reassembly (54) of the rotor on the transmission shaft of a vehicle, - operation (56) of the eddy current device.

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