Grounding device for a rotating electrical machine.
The grounding device with a conductive main body and secondary body, featuring conductive fibers and a grounding lug, addresses the limitations of existing solutions by providing adjustable and replaceable components to manage high-frequency parasitic currents, ensuring effective and durable bearing protection in rotating electrical machines.
Patent Information
- Application Number
- FR2023002687
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2023-03-22
- Publication Date
- 2025-10-03
- Estimated Expiration
- 2043-03-22
AI Technical Summary
Existing grounding solutions for rotating electrical machines are limited by maximum rotation speed, generate noise and heat, and increase mechanical effort due to friction, while failing to effectively manage high-frequency parasitic bearing currents caused by rapid power electronics commutations.
A grounding device with a conductive main body and secondary body, featuring conductive fibers and a grounding lug, is mounted on a ventilation cover with reversible locking means, allowing adjustable positioning and easy replacement or repositioning to manage induced leakage currents.
The device effectively grounds induced leakage currents, reduces wear-related issues, and maintains functionality across varying rotation speeds without noise or excessive mechanical stress, ensuring long-term bearing protection.
Smart Images
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Abstract
Description
Title of the invention: Device for grounding a rotating electric machine.
[0001] The present invention relates to the field of bearing current management in electrical rotating machines.
[0002] More specifically, the present invention relates to an electrically conductive contact device allowing the grounding of a rotating shaft using conductive fibers, in particular for a rotating electrical machine, for example an electric motor or a generator in operation.
[0003] Bearing currents in rotating electrical machines are well known, and their deleterious effects on them are also well known.
[0004] Bearing currents have always existed in electric motors and are the cause of a large number of faults, including the gradual deterioration of the motor's bearing tracks.
[0005] Indeed, high-power asynchronous motorization chains have entered a phase of maturity for several years. However, problems remain, linked to the power supply of these motors by static converters whose commutations are increasingly rapid. The voltage fronts generated by the commutations of the power electronics are at the origin of the development of parasitic currents propagating throughout the entire electrical rotating machine. Their circulation is linked to complex phenomena from both an electrostatic and magnetic point of view and this in the high frequency domain. Current orders of magnitude commonly lead to phenomena in the MHz frequency range. Some of these currents pass through the bearings of the electrical rotating machine and, depending on their amplitudes, are likely to cause degradation in the more or less long term.
[0006] When motor shaft voltages exceed the insulating capacity of the bearing grease, currents directed toward the outer bearing can occur and cause pitting and gouging of the bearing rings. These currents are caused by the buildup of electrostatic energy at the machine rotor, which suddenly discharges when the electric field is sufficient to “break” the insulating grease in the bearings. This problem initially manifests itself as noise accompanied by overheating, due to the fact that the bearings begin to lose their original shape and fragments of metal mix with the grease and increase friction. This can cause the destruction of the bearing in just a few months.
[0007] To prevent this degradation, it is known that it is appropriate to establish the earthing of the motor, that is to say of its casing and its shaft, for example according to the solution described in application WO9701200 which provides a carbon tip held in contact with the casing of the motor by means of a spring.
[0008] Such solutions have the disadvantage of being limited by a maximum rotation speed of the motor, by heating due to contact, greater friction, greater mechanical effort, and the disadvantage of making noise in use.
[0009] The solution developed by the applicant in application FR3119053 makes it possible to resolve these drawbacks.
[0010] The present invention aims to further improve the state of the art by allowing a particularly clever implementation of an earthing device.
[0011] In this context, the present invention relates, according to a first of its objects, to a device (1000) for earthing an electric rotating machine (300), the electric rotating machine (300) comprising a rotating shaft (310), a rotor (320) and a ventilation cover (330),
[0012] said grounding device being configured to be mounted on the ventilation cover (330) in a removable manner, and comprising:
[0013] - an electrically conductive main body (100), having an elongated shape, and supporting at one of its ends a set of conductive fibers (110) arranged to allow the grounding of induced leakage currents relating to the rotor (320) in the electric rotating machine (300), and a grounding lug (120) at the other of its ends.
[0014] It is essentially characterized in that it further comprises:
[0015] • blocking means; and
[0016] • a secondary body (200), comprising:
[0017] o a hub (210) whose shape locally matches that of the main body (100), and
[0018] o a fixing plate (230), integral with the hub (210);
[0019] And in that
[0020] • the main body (100) is movable in translation relative to the secondary body (200);
[0021] • the fixing plate (230) is configured to fix the secondary body (200) on the ventilation hood (330);
[0022] • the locking means are configured to block the translational movement of the main body (100) relative to the secondary body (200) and ensure temporary joining of the main body (100) and the secondary body (200).
[0023] It can be provided that the blocking means comprise:
[0024] • a through hole (220) tapped radially in the hub (210) of the body se- secondary (200), and
[0025] • a screw, insertable into the tapped hole (220), and configured to come into abutment against the main body (100) when the main body (100) is inserted into the hub (210) of the secondary body (200), so as to block the translation of the main body (100) in the hub (210) of the secondary body (200).
[0026] It can be provided that the blocking means comprise:
[0027] • a set of at least one radial through hole (130) in the main body (100)
[0028] • a set of at least one through hole (250) secured to the secondary body (200); and
[0029] • a pin, configured to be able to be removably inserted into said assembly of at least one radial through hole of the main body (100) and the through hole secured to the secondary body (200).
[0030] It may be provided that the locking means comprise a quick-tightening connection, comprising:
[0031] - a thread (261) on the external part of the secondary body (200), acting as male body;
[0032] - a nut (260), acting as a female body, the threading of which corresponds to the thread (261) of the secondary body (200); and
[0033] - a seal between the thread of the secondary body (200) and the nut secured to the body main (100).
[0034] In particular, the seal may be in the form of a claw, an olive or a ring.
[0035] It can be provided that the locking means are reversible, so as to allow the separation of the main body (100) and the secondary body (200).
[0036] It can be provided that the main body (100) has a radially symmetrical section.
[0037] It can be predicted that:
[0038] • the main body (100) has a round section and an external face having a thread (140);
[0039] • the hub (210) of the secondary body (200) has a thread (240), completed additional thread (140) of the main body (100), such that screwing the main body (100) into the hub (210) of the secondary body (200) allows a translational movement to be carried out
[0040] It may be provided that the set of conductive fibers (110) of the main body (100) comprises a plurality of bundles (111) of conductive fibers (110), the length of the fibers within a bundle (111) or the length of the fibers between two bundles (111) being able to be different.
[0041] According to another of its objects, the invention relates to a ventilation hood (330) of electrical rotating machine (300) comprising an earthing device according to the invention, in which the earthing device is fixed to the ventilation cover (330) by its fixing plate (230).
[0042] According to another of its objects, the invention relates to an electric rotating machine (300) comprising a rotating shaft (310), a rotor (320), a ventilation cover (330) and an earthing device according to the invention.
[0043] Finally, the invention also relates to a kit comprising an earthing device according to the invention, and an assembly of at least one other main body (100).
[0044] Other characteristics and advantages of the present invention will appear more clearly on reading the following description given by way of illustrative and non-limiting example and made with reference to the appended figures.
[0045] *Figures*
[0046] [Fig. 1] illustrates an embodiment of an earthing device according to the invention in three-quarter view;
[0047] [Fig.2] illustrates the grounding device of [Fig.l] according to another three-quarter view;
[0048] [Fig.3] illustrates an embodiment of a main body and a secondary body of an earthing device according to the invention before insertion of the main body into the secondary body;
[0049] [Fig.4] illustrates in cross-section, an embodiment of a main body comprising a first embodiment of bundles of conductive fibers;
[0050] [Fig.5] illustrates in cross-section, an embodiment of a main body comprising another embodiment of bundles of conductive fibers;
[0051] [Fig.6] illustrates an embodiment of a main body and a secondary body of an earthing device according to the invention, for securing by pin;
[0052] [Fig.7] illustrates an embodiment of a main body and a secondary body of an earthing device according to the invention, for connection by screwing;
[0053] [Fig.8] illustrates in a partially exploded view an electric rotating machine ready to be equipped with an earthing device according to the invention;
[0054] [Fig.9] illustrates the electric rotating machine of [Fig.8] in which the earthing device according to the invention is in contact with the rotating shaft;
[0055] [Fig. 10] illustrates the electric rotating machine of [Fig.9], in enlarged and three-quarter view;
[0056] [Fig. 11] illustrates an embodiment of locking means according to the invention comprising a quick-tightening connection.
[0057] [Fig.l] illustrates an embodiment of an earthing device according to the invention in three-quarter view. The earthing device comprises a body main 100 electrical conductor which has an elongated shape.
[0058] At one of its ends it supports a set of conductive fibers 110 arranged in this case in a plurality of bundles 111, to allow the conduction of leakage currents.
[0059] At the other of its ends, it supports a grounding lug 120, to allow the grounding of leakage currents.
[0060] It also comprises a secondary body 200, which comprises a hub 210 and a fixing plate 230, integral with the hub 210. The shape of the hub 210 locally matches that of the main body 100, as illustrated in [Fig. 3]. The main body 100 can be movable in translation in the hub 210, therefore movable in translation relative to the secondary body 200.
[0061] The fixing plate 230 allows the secondary body 200 to be fixed in a removable manner on a ventilation cover 330 of an electric rotating machine 300, in this case thanks to a set of recesses 231 which allow the passage of fixing screws, rivets or other fixing means (bolting etc.).
[0062] According to the invention, locking means are also provided to block the translational movement of the main body 100 relative to the secondary body 200 and to ensure temporary joining of the main body 100 and the secondary body 200.
[0063] In a first embodiment, illustrated in [Fig.l] and [Fig.2], the locking means comprise a through hole 220 tapped radially in the hub 210 of the secondary body 200.
[0064] In this case, a screw is provided that can be inserted into the tapped hole 220. The length of the screw is chosen so that it can come into abutment against the main body 100 when the main body 100 is inserted into the hub 210 of the secondary body 200, so as to block the translation of the main body 100 in the hub 210 of the secondary body 200, see [Fig.l].
[0065] In a second embodiment, illustrated in [Fig.6], the locking means comprise a set of at least one hole 130 passing radially through the main body 100, and arranged axially.
[0066] A set of at least one through hole 250 is also provided, integral with the secondary body 200 and arranged radially therein.
[0067] Preferably, the diameter of the through holes 130 and the through hole 250 are equal.
[0068] A pin, or peg, is also provided, configured to be able to be inserted removably into said assembly of at least one through hole 130 of the main body 100 and the assembly of at least one through hole 250 secured to the secondary body 200, which blocks the main body 100 in translation relative to the body secondary 200.
[0069] When the main body 100 comprises a plurality of through holes 130, the choice of a particular through hole 130 makes it possible to adjust the position of the end of the conductive fibers 110 relative to the electrical rotating machine 300, thus allowing the grounding of leakage currents.
[0070] A plurality of through holes 250, arranged radially, may be provided in order to increase the flexibility of use by the number of angular positions that the main body 100 can take relative to the secondary body 200.
[0071] In a third embodiment, illustrated in [Fig.7], the locking means comprise a thread 140 arranged on an external face of the main body 100 which has a round section.
[0072] In this case, the hub 210 of the secondary body 200 has a thread complementary to the thread 140 of the main body 100.
[0073] The main body 100 can thus be screwed into the hub 210 of the secondary body 200, which makes it possible to perform a translational movement and thus to adjust the position of the end of the conductive fibers 110 relative to the rotating electric machine 300, thus allowing the leakage currents to be grounded.
[0074] In a fourth embodiment, the locking means comprise quick-tightening connectors, in particular so-called “bi-cone” or “olive” connectors, comprising a threaded male body and a corresponding female nut. Claw connectors can also be provided. In [Fig. 1 1], the secondary body 200 has a thread 261. When the main body 100 is inserted into the secondary body 200, a nut 260 whose thread corresponds to the thread 261 of the secondary body 200 makes it possible to temporarily secure the main body 100 and the secondary body 200.
[0075] Advantageously, whatever the embodiment of the locking means, these are reversible, so as to allow the separation of the main body 100 and the secondary body 200.
[0076] Thus, the translational movement of the main body 100 relative to the secondary body 200 is temporarily blocked and the joining of the main body 100 and the secondary body 200 is temporary.
[0077] It is thus possible, for example, to reposition a main body and bring it closer to the electric rotating machine 300 to compensate for the shortening of the length of the conductive fibers, which decreases due to their wear in contact with it.
[0078] It is also possible to replace a used main body, the conductive fibers of which are worn, with a new main body the conductive fibers of which are new.
[0079] Preferably, the main body 100 has a section with radial symmetry, for example round or regular polygonal.
[0080] However, other shapes can be provided, for example an oval section, provided that that the shape of the hub 210 matches that of the main body 100. Such a non-regular shape makes it possible, for example, to serve as a foolproofing device to impose certain relative positions of the main body 100 and the secondary body 200.
[0081] On one end of the main body 100, the conductive fibers 110 are for example grouped into a plurality of bundles 111 of conductive fibers. For example in [Fig.2], the main body 100 comprises bundles 111 of conductive fibers arranged at the periphery of the end of the main body 100, in a circular manner. In this example, the conductive fibers 110 all have the same length.
[0082] Alternatively, it can be provided that the length of the conductive fibers 110 within a bundle 111 is different, as illustrated in [Fig.4].
[0083] It can also be provided that within a bundle 111, the conductive fibers 110 have the same length but that this length differs from one bundle 111 to another, as illustrated in [Fig.5].
[0084] Whatever the embodiment previously described, it can be provided that the main body 100 comprises a set of graduations 101 inscribed thereon, as illustrated in [Fig. 3], which makes it possible to adjust the position of the main body 100 relative to the secondary body 200, in particular in the event of wear of the conductive fibers 110. Whatever the embodiment previously described, the earthing device 1000 is fixed to the ventilation cover 330 of an electric rotating machine 300 by its fixing plate 230, as illustrated in [Fig. 8] and [Fig. 9].
[0085] In [Fig. 10], the grounding device 1000 is fixed to the ventilation cover 330 of an electric rotating machine 300 by the fixing plate 230 of the secondary body 200. The conductive fibers 110 are in contact with the rotating shaft 310. The induced bearing currents which travel through the rotating shaft 310 can thus be grounded by passing along the conductive fibers 110, the main body 100 and the grounding lug 120.
[0086] When the conductive fibers 110 are worn, the fixing plate 230 of the secondary body 200 can remain fixed on the ventilation cover 330. It is sufficient either to adjust the relative position of the main body 100 and the secondary body 200, so that the conductive fibers 110 are again in contact with the rotating shaft 310; or to replace the used main body 100 with a new main body 100, which is very quick.
[0087] Nomenclature
[0088] 1000 Grounding device
[0089] 100 main body
[0090] 101 graduations
[0091] 110 conductive fibers
[0092]
[0093]
[0094]
[0095]
[0096]
[0097]
[0098]
[0099]
[0100]
[0101]
[0102]
[0103]
[0104]
[0105]
[0106]
[0107]
[0108] 111 bundle of conductive fibers 120 grounding lug 130 radial through hole in the main body 140 thread 200 secondary body 210 hub 220 threaded through hole 230 fixing plate 231 recess in the plate 230 240 thread in the hub 250 through hole secured to the secondary body 260 nut 261 thread of the secondary body 300 electric rotating machine 310 rotating shaft 320 rotor 330 cover of ventilation
Claims
Claims
1. Device (1000) for grounding an electric rotating machine (300), the electric rotating machine (300) comprising a rotating shaft (310), a rotor (320) and a ventilation cover (330), said grounding device being configured to be mounted on the ventilation cover (330) in a removable manner, and comprising: - an electrically conductive main body (100), having an elongated shape, and supporting at one of its ends a set of conductive fibers (110) arranged to allow the grounding of induced leakage currents relating to the rotor (320) in the electric rotating machine (300), and a grounding lug (120) at the other of its ends; characterized in that it further comprises: • blocking means; and • a secondary body (200), comprising: • a hub (210) whose shape locally matches that of the main body (100), and • a fixing plate (230), secured to the hub (210); And in that • the main body (100) is movable in translation relative to the secondary body (200); • the fixing plate (230) is configured to fix the secondary body (200) on the ventilation cover (230); • the blocking means are configured to block the translational movement of the main body (100) relative to the secondary body (200) and ensure temporary joining of the main body (100) and the secondary body (200), making it possible to adjust the position of the end of the conductive fibers (110) relative to the rotating electrical machine (300), thus allowing the grounding of leakage currents.
2. Device according to claim 1, in which the means of locking comprises: • a through hole (220) tapped radially in the hub (210) of the secondary body (200), and • a screw, insertable into the tapped hole (220), and configured to come into abutment against the main body (100) when the main body (100) is inserted into the hub (210) of the secondary body (200), so as to block the translation of the main body (100) in the hub (210) of the secondary body (200).
3. Device according to claim 1, wherein the locking means comprise: • a set of at least one radial through hole (130) in the main body (100); • a set of at least one through hole (250) secured to the secondary body (200); and • a pin, configured to be able to be removably inserted into said set of at least one radial through hole of the main body (100) and the through hole secured to the secondary body (200).
4. Device according to claim 1, in which the locking means comprise a quick-tightening connection, comprising: - a thread (261) on the external part of the secondary body (200), acting as a male body; - a nut (260), acting as a female body, the threading of which corresponds to the thread (261) of the secondary body (200); and - a seal between the thread of the secondary body (200) and the nut secured to the main body (100).
5. Device according to any one of the preceding claims, in which the locking means are reversible, so as to allow the separation of the main body (100) and the secondary body (200).
6. Device according to any one of the preceding claims, in which the main body (100) has a radially symmetrical section.
7. A device according to any preceding claim, wherein: • the main body (100) has a round section and an external face having a thread (140); • the hub (210) of the secondary body (200) has a thread (240), complementary to the thread (140) of the main body (100), such that screwing the main body (100) into the hub (210) of the secondary body (200) allows a translational movement to be carried out
8. A device according to any preceding claim, wherein the set of conductive fibers (110) of the main body (100) comprises a plurality of bundles (111) of conductive fibers (110), the length of the fibers within a bundle (111) or the length of the fibers between two bundles (111) being able to be different.
9. An electric rotating machine (300) comprising a rotating shaft (310), a rotor (320), a ventilation cover (330) and a grounding device according to any one of claims 1 to 7.
10. A kit comprising a grounding device according to any one of claims 1 to 7, and an assembly of at least one other main body (100).