Patent Application
20230344314
The present application relates to a rotary electric machine.
Among rotary electric machines, rotary electric machines with brushes such as alternators, motor generators, etc. for use in vehicles are required to be provided with air permeability for getting cooled. However, under actual use conditions, these machines may be soaked with liquids.
In this regard, there is disclosed a rotary electric machine provided with a fitting sleeve serving as both a brush holder and a slipring cover, in which a single web is provided in a region inside the fitting sleeve and near an end edge portion thereof, so that the rotary electric machine is both air-permeable and capable of blocking a liquid from intruding internally (see, for example, Patent Document 1). Further, there is disclosed a rotary electric machine in which a labyrinth seal for changing a fluid flow from axial to radial is formed at an end portion of the brush holder or the slipring cover, so that the rotary electric machine is both air-permeable and capable of preventing intrusion of a foreign substance (see, for example, Patent Document 2).
However, in the case where the brush assembly is segmented into multiple components as represented by the combination of the brush holder and the slipring cover, a slight gap is formed between the components. Further, according to such a barrier-forming structure as disclosed in the foregoing Patent Documents, even though a liquid is prevented from being splashed directly to the slipring or the brush, it may partially remain in the inner side of the barrier. Accordingly, a case may arise where the liquid remaining in the inner side of the barrier reaches the slipring or the brush by later vibrations or the like and thus, it is difficult only by simply forming the barrier, to prevent a liquid from intruding to the brush. Thus, impurities such as a salt, etc. included in the liquid may be firmly adhered to and accumulated on the brush, so that the operation or power generation of the rotary electric machine may possibly be stopped due to sticking of the brush.
This application discloses a technique for solving such a problem as described above, and an object thereof is to provide a rotary electric machine which can prevent a liquid from intruding to the brush.
A rotary electric machine disclosed in this application is characterized by comprising: an annular stator; a rotor having a field winding and located on an inner circumferential-surface side of the stator; a shaft that rotatably supports the rotor and is provided with a slipring for supplying a current to the field winding, said slipring being placed on an outer circumferential surface of an end portion of the shaft located on its one end side and projecting from the rotor; a brush assembly that has a cylindrical shape with an open end located near a head of the shaft, to thereby surround the slipring; and a brush that penetrates in the brush assembly toward the slipring from its radially outer side and makes contact with the slipring, for supplying a current to the slipring;
According to the rotary electric machine disclosed in this application, since the flow passage sandwiched by the spaced-apart walls and extending in the circumferential direction is formed on the inner circumferential surface of the brush assembly, it is possible to prevent a liquid from intruding to the brush.
A rotary electric machine 1 according to Embodiment 1 is a rotary electric machine with a brush for use in vehicles, which includes, as shown in
The rotor 8 is supported in the casing 4 by a shaft 6 that has a fan 9a and a fan 9b fixed at both end faces of that shaft in terms of the direction of an axis (rotation axis X), and that is rotatably supported by the casing 4 through a pair of bearings 5. In addition, a pulley 7 is firmly fixed to the shaft 6 at its end portion extending toward the front side (right side in this figure). Further, the stator 10 is fixed to the casing 4 on its inner circumferential-surface side so as to surround the rotor 8 through an unshown gap.
A pair of sliprings 11 for supplying a current to the rotor 8 is fixed to an outer circumferential surface of the shaft 6 at its extending portion extending toward the rear side (left side in this figure) of the casing 4 and projecting outward from the rear bracket 3. On the outer circumferential side of the sliprings 11, a rectifier 12 for rectifying an AC voltage generated in the stator 10, that is fabricated almost into a C-shape, is disposed to form in a plane perpendicular to the rotation axis X, a fan-like shape around the shaft 6.
Here, the aforementioned brush assembly 20 is configured with a combination of a brush holder 21 interposed between both ends of the almost C-shaped rectifier 12 and a slipring cover 22, etc., and is disposed on an outer circumferential side of the extending portion of the shaft 6 so as to cover the pair of sliprings 11. To the brush assembly 20, a voltage regulator 13 for regulating the magnitude of the AC voltage generated in the stator 10 is attached.
On the rear side of the rear bracket 3, an unshown connector for performing signal input/output between the voltage regulator 13 and an unshown external device or the like, is located. Further, a protective cover 14 made of an insulating resin is attached to the rear bracket 3 so as to cover the aforementioned connector, the rectifier 12, the brush holder 21 and the voltage regulator 13.
Next, the brush assembly 20 will be detailed. As shown in
Namely, an arc-like wall member as the slipring cover 22 that constitutes a majority of the circumferential portion, is combined with an arc-like part of the brush holder 21 that constitutes less than half of the circumferential portion, to thereby form a cylindrical shape which surrounds the sliprings 11 and whose end portion corresponding to a head of the shaft 6 forms an open end.
As shown in
In the brush holder 21, brush storage sections 23a are formed in which the brushes 23 and the springs 26 for pressing the respective brushes 23 against the respective opposite-side surfaces of the paired sliprings 11 (positive and negative electrodes) with a pressing force Pp directed to the radially inner side of the sliprings 11, are stored. Furthermore, pig-tail storage sections 25a are formed in which the pig tails 25 that are soldered to the connection terminals 24 embedded in the brush holder 21 and are electrically connected with the brushes 23 are stored.
With such a configuration, even if the brush 23 is abraded due to sliding on the slipring 11 caused by the rotation of the slipring 11, the brush 23 is pressed constantly against the slipring 11 because of the repulsion force from the spring 26. This makes it possible to continuously establish the electrical connection therebetween.
The configuration described so far is similar to that of a conventional rotary electric machine, so that a characteristic configuration of the rotary electric machine 1 according to Embodiment 1 will be described on the premise of the above configuration.
As shown in
By the way, according to the conventional rotary electric machine for use in vehicles, intrusion of a liquid applied from the rear side can be somewhat prevented by means of the protective cover; however, a case may arise where the liquid reaches the brush holder or the slipring cover. The liquid adhered to the brush holder or the slipring cover is a liquid that has intruded from the side of the end edge surface of the brush holder or through a gap between components. Since impurities such as a salt, etc. are included in the thus-intruded liquid, these impurities, when dried, will be tightly adhered to the inside of the brush holder or the slipring cover. These impurities may be accumulated through repeated drying and adhesion, to reach the brush. If the brush is sticked with the salt, etc., the function of pressing the brush against the slipring by using the repulsion force of the spring will be suppressed. When the thus-sticked brush is abraded due to sliding on the slipring, a gap will be created and the electrical connection point will disappear, thus resulting in stoppage of the operation or power generation of the rotary electric machine for use in vehicles.
Accordingly, it is conceivable to prevent a liquid from intruding to the slipring or the brush by forming the barrier as explained in “Description of the Background Art”. However, by merely forming the barrier, a case may arise where, even though direct splash of the liquid is prevented, the liquid partially remains in the inner side of the barrier and the remaining liquid reaches the slipring or the brush by later vibrations or the like. Thus, it is difficult to prevent a liquid from intruding to the brush.
In contrast, in the rotary electric machine 1 according to Embodiment 1, on a portion of the inner circumferential surface of the brush assembly 20 on the brush holder 21-side, the first wall 27f and the second wall 27b that project toward the rotation axis X and are arc-like, are formed to be axially spaced apart from each other. Between the first wall 27f and the second wall 27b, a flow passage 28 that leads to an outside of the region of the brush holder 21 is formed along the circumferential direction.
Accordingly, if a liquid passes through the first wall 27f that is positioned closer to the end edge portion 22fe than the flow passage 28 and serves to prevent a liquid from being splashed directly toward the slipring 11 or the brush 23, it will be kept staying in the flow passage 28 between that wall and the second wall 27b. Even if the staying liquid is subjected to vibrations or impacts due to travelling of a vehicle, it will go to the outside of the region of the brush holder 21 (an arrangement region of the brushes 23), not along the axial direction but along the circumferential direction in the flow passage 28.
This makes it possible, if the remaining liquid is subjected to vibrations or impacts, or if there is a liquid having passed through a boundary portion 20b between the brush holder 21 and the slipring cover 22, to guide such a liquid in a circumferential direction, to thereby prevent it from intruding toward the brush 23. Moreover, since multiple concavities and convexities are formed along the axial direction, the surface area of the inner circumferential surface increases, so that the liquid will be dried more easily. Thus, if impurities such as a salt, etc. are going to be accumulated, they become more difficult to reach the brush 23, so that the sticking of the brush 23 is suppressed.
On that occasion, when the width of the flow passage 28 (flow-passage width W28:
In Embodiment 1, a case has been described where the flow passage having a uniform width is formed along a circumferential direction by using two walls. In Embodiment 2, a case will be described where the end portions of the second wall are bent toward the brush so that the flow-passage width thereat expands toward the brush.
In Embodiment 1, the first wall 27f and the second wall 27b formed on the inner circumferential surface on the side of the brush holder 21 as a slipring holder, are each configured to extend along a plane perpendicular to the axial direction. However, in Embodiment 2, as shown in
Since the both end portions 27be in the circumferential direction of the second wall 27b that is closest to the brush 23 are bent toward the brush 23, the liquid having entered in the flow passage 28 will go using its kinetic energy, more smoothly along the circumferential direction to the outside of the arrangement region of the brush 23. This enhances the effect of capturing a liquid that has intruded, for example, through the boundary portion 20b between the brush holder 21 and the slipring cover 22 to thereby prevent the liquid from flowing in toward the brash 23.
Accordingly, it becomes possible to suppress the sticking of the brush 23 more significantly. On that occasion, it is preferable that the flow-passage width W28 at a middle portion in the circumferential direction of the flow passage (its portion corresponding to the projecting region of the brush 23) be within the range shown in Embodiment 1; however, the width at its portions closer to the both ends than the middle portion may be wider than that range.
It should be noted that, in this application, a variety of exemplary embodiments and examples have been described; however, every characteristic, con-figuration or function that has been described in one or more embodiments, is not limited to being applied to a specific embodiment, and may be applied singularly or in any of various combinations thereof to another embodiment. Accordingly, an infinite number of modified examples that have not been exemplified here are supposed within the technical scope disclosed in the present description. For example, such cases shall be included where at least one configuration element is modified; where at least one configuration element is added or omitted; and furthermore, where at least one configuration element is extracted and combined with a configuration element disclosed in another embodiment.
For example, although such cases have been shown where one flow passage 28 is formed by the first wall 27f and the second wall 27b, this is not limitative. Multiple flow passages may be formed by forming a much larger number of walls, for example, additionally forming a third wall and a fourth wall. Further, a flow passage may be formed between the rib 22r and the first wall 27f. Further, such embodiments have been shown in which the brush assembly 20 is a combination of the slipring cover 22 and the brush holder 21 that are divided in a circumferential direction, and has the boundary portion 20b therebetween; however, the brush holder is not limited thereto, and may be seamlessly combined.
As described above, the rotary electric machine 1 of this application is configured to comprise: the annular stator 10; the rotor 8 having a field winding and located on an inner circumferential-surface side of the stator 10 so as to be rotatably supported coaxially with the stator 10 on the inner circum-ferential-surface side thereof; the shaft 6 that rotatably supports the rotor 8 and is provided with the sliprings 11 for supplying a current to the field winding, said sliprings being placed on an outer circumferential surface of an end portion of the shaft located on its one end side and projecting from the rotor 8; the brush assembly 20 that has a cylindrical shape with an open end located near a head of the shaft 6, to thereby surround the sliprings 11; and the brushes 23 that penetrate in the brush assembly 20 toward the sliprings 11 from their radially outer sides and make contact with the sliprings 11, for supplying a current to the sliprings 11;
wherein the first wall 27f and the second wall 27b are formed on an inner circumferential surface of the brush assembly 20 between the open end (end edge portion 22fe) and the brushes 23, said first wall extending in a circumferential direction while projecting radially inwardly, and said second wall being placed to be spaced apart from the first wall 27f on its side closer to the brushes 23 than the first wall, and forming between it and the first wall 27f, a flow passage that leads in the circumferential direction from a region corresponding to the penetrating region of the brushes 23, to the outside thereof. With this configuration, it is possible to prevent a liquid from being splashed directly to the sliprings 11 or the brushes 23. Moreover, if the liquid passes through the first wall 27f, the liquid staying in the flow passage 28 between that wall and the second wall 27b, even if it is subjected to vibrations or impacts due to travelling of a vehicle, will go in the flow passage 28 to the outside of the region of the brush holder 21, not along the axial direction but along the circumferential direction in the flow passage 28. Thus, it is possible to prevent a liquid from intruding to a contact portion between the brush 23 and the slipring 11.
In particular, with such a configuration in which, as the flow passage 28 goes toward both ends thereof in the circumferential direction, it expands so as to become closer to the brush 23, it is possible to enhance the effect of capturing a liquid that has intruded through the boundary portion 20b between the brush holder 21 and the slipring cover 22 to thereby prevent the liquid from flowing in toward the brash 23.
In addition, when the width of the flow passage 28 in an axial direction (flow-passage width W28) at a region in the circumferential direction corresponding to the penetrating region of the brush 23, is set to be not less than 1 mm but not more than 10 mm, the liquid remaining in the flow passage 28, even if it is subjected to vibrations or impacts, can be guided smoothly along the circumference direction in the flow passage 28 without going beyond the second wall 27b.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-069826 | Apr 2022 | JP | national |
