FR2842362A1 - Power steering electrical rotating machine having stator hub and rotor inside and having fixed magnet outside with protrusion/non magnetic protector element protrusion placed covering angled part. - Google Patents

Abstract

The electrical rotating machine has a stator hub (10) and a rotor (4) inside. There is a fixed magnet on the outside (20) with a protrusion (21). There is a non magnetic protector element (23) placed in the protrusion to cover an angle part (22) of the peripheral face.

Description

ROTATING ELECTRICAL MACHINE

  BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates to a rotary electric machine having a fixed magnet on the

  outer circumference of a rotor.

  Related Art The conventional device having a magnet attached to the outer circumference of a rotor has been proposed in Examined Japanese Patent Application No. 5205979 and Japanese Unexamined Patent Application No. H127-284237, for example. In Examined Japanese Patent Application No. 5155979, a cylindrical yoke is attached to a rotating shaft, a plurality of arcuate magnets are welded to the outer peripheral face of the yoke, and an adhesive is applied to the inner faces of the yoke. two cup-shaped protective housings made of a non-magnetic material which are then associated together from both axial sides of the rotating shaft to cover the magnets, wherein the protective housings substantially cover the outer faces of the magnets. The magnets covered by the protective housings are prevented from dispersing under the effect of the centrifugal force associated with the rotation

of the rotor.

  The device as proposed by the unexamined patent application N0Hei7-284237 comprises an iron core rotor having a shaft, a plurality

SR 22624 JP / JB

  permanent magnets arranged around the periphery of the iron core rotor and connection means for firmly connecting the permanent magnets to the iron core rotor, wherein the connecting means is a plurality of annular elements surrounding the iron core rotor; plurality of the permanent magnets and spaced from each other in the axial direction, the plurality of annular elements being in close contact with the radial outer faces of the plurality of permanent magnets and the connecting means being capable of connecting the magnets

  permanent firmly and powerfully to the iron core.

  In the aforementioned conventional device patents, the relationship between the stator core and the protective housings or annular elements is not described, but it is assumed that the protective housings or annular elements are disposed in a space between the peripheral face inside of the stator core and the outer peripheral face of the rotor, so that the size of the space is increased by an amount corresponding to the thickness

  protective housings or annular elements.

  If the conventional device is constituted in the manner described above, the protective housings or the annular elements disposed in the space between the inner peripheral face of the stator and the outer peripheral face of the magnet, it is necessary to increase the space size of an amount corresponding to the thickness of the protective housings or annular elements, which results in a degradation of the performance of the engine. In the

SR 22624 JP / JB

  conventional device, the outer surface of the magnet is substantially covered by the protective housings, so that the protective housings become larger and a plurality of annular elements are disposed at an axial proximity of the magnet, which results in an extra cost, a complicated assembly and a greater loss of eddy current. In addition, the magnet is often broken or cracked at the corner portion, particularly at the time of assembly and is provided with

  a protection element near the axial center.

  However, if the protective element has not been deposited on the corner portion of the magnet, the effect

  protector of the element does not materialize.

  SUMMARY OF THE INVENTION The present invention is related to the aforementioned problems and one of the objects of the present invention is to propose a rotary electric machine which can effectively avoid the breakage of the magnet, which can be expensive and allows high productivity and

  presents an excellent performance.

  A rotary electric machine according to the first embodiment of the present invention comprises a stator core, a rotor disposed in the inner periphery of the stator core and a magnet fixed on the outer periphery of the rotor with a certain spacing of the inner peripheral face. of the stator core, characterized in that the magnet has a protrusion projecting in the axial direction from the two axial end faces of the stator core

SR 22624 JP / JB

  and a non-magnetic material protective member disposed on the projection for covering at least a corner portion of the outer peripheral face of the projection. The rotary electric machine according to the second embodiment of the present invention is characterized in that the rotor has a magnet fixed on the outer peripheral face of a portion of

  cylinder head formed integrally with a tree.

  The rotary electric machine according to a third embodiment of the present invention is characterized in that a plurality of magnets having an arcuate shape is fixed on the outer periphery of the rotor, each magnet being

magnetized in multiple poles.

  The rotary electric machine according to a fourth embodiment of the present invention is characterized in that the protective element is realized

in stainless.

  The rotary electric machine according to a fifth embodiment of the present invention is characterized in that the protective element has the shape of a cup which covers the outer peripheral surface of the protrusion of the magnet and a face

axial end.

  The rotary electric machine according to a sixth embodiment of the present invention is characterized in that the protective element is welded to the magnet. The electric machine according to a seventh embodiment of the present invention is characterized

SR 22624 JP / JB

  in that the rotary electric machine is used

  for an electric power steering motor.

Brief description of the drawings

  FIG. 1 is a sectional view showing a motor part of a brushless motor intended for hydraulic power steering according to a first embodiment of FIG.

  embodiment of the present invention.

  FIG. 2 is a sectional view of a rotor according to the first embodiment of the present

  invention, taken in the axial direction.

  FIG. 3 is a sectional view of a rotor according to the second embodiment of the present invention,

taken in the radial direction.

  FIGS. 4A and 4B are front and sectional views taken along the line A-A of a protective element according to the first embodiment of FIG.

present invention.

  FIG. 5 is a sectional view of a rotor according to the first embodiment of the present

  invention, taken in the radial direction.

  FIG. 6 is a sectional view of a rotor according to the second embodiment of the present invention,

taken in the axial direction.

  FIGS. 7A and 7B are front and sectional views taken along the line B-B of a protective element according to the second embodiment of FIG.

present invention.

  FIG. 8 is a sectional view of a rotor according to the third embodiment of the present invention.

  invention, taken in the axial direction.

SR 22624 JP / JB

  Detailed Description of the Preferred Embodiments

  Embodiment 1 Fig. 1 is a sectional view showing a motor part of a brushless motor for hydraulic power steering, according to a first embodiment of the present invention. Figure 2 is a sectional view of a rotor taken in the axial direction. Figure 3 is a sectional view of a rotor taken in the axial direction. Figure 4A is a front view of a protective member and Figure 4B is a sectional view of the protective member taken along the line A-A. Identical or similar parts are indicated by like reference numerals in all the figures. In Figure 1, 1 indicates a motor having a stator 3 fixed by fitting to the inner circumference of a frame 2 consisting of a steel plate and a rotor 4 disposed with a certain space of the inner periphery face of the stator 3 The rotor 4 is supported by a bearing 6 provided on the housing 5 made of aluminum and a bearing 7 provided on the frame 2 to rotate freely. The bearing 6 has an outer ring embedded in the housing 5. The rotor 4 is fixed to an inner ring of the bearing 6 and has movement limiting means

  axial to limit the axial movement of the rotor 4.

  The stator 3 has a nylon molded coil and mounted with insulation in the core of the stator 10 having laminated electromagnetic steel plates in which the stator coil 13 is

SR 22624 JP / JB

  The stator coil 13 has a cable diameter of approximately 1 to Q2 and is made of an enamelled copper cable. A terminal of the coil 14 is arranged such that the start or end of the choke coil 13 is subjected to a predetermined connection (e.g., a three-phase delta connection) by a coil connection body disposed on the side of the stator 3. A power source for supplying the motor 1 is connected to a connection terminal 16 provided for the coil connection body 15. A coupling key 17 takes hold on the coil 11, so that the body of

  coil connection 15 is integrated in the stator 3.

  In FIGS. 1 to 4, the rotor 4 has a yoke portion 19 formed integrally with a shaft 18 and forming an iron core, three ferrite magnets 20 have substantially the same size as the axial length of the yoke portion 19, with a circular arc shape, in section, are fixed by adhesives on the outer peripheral face of the yoke portion 19. Each magnet 20 has a projection 21 extending parallel to the inner peripheral surface of the stator core 10 and protruding axially from any of the axial end faces of the stator core 10, an angled portion 22 of the outer peripheral face of the projection 21 being covered by the protector member 23. The Protective element 23 has a cup shape, as shown in Figure 4, and is pressed into a stainless steel plate with a thickness of 0.1 mm, for example. The element

SR 22624 JP / JB

  protector 23 is inserted into the projection 21 of the magnet and fixed by adhesives. In addition, the magnet 20 is magnetized into six poles, after the protective element

  23 be implemented, as shown in Figure 3.

  The lower diameter d of the stator 3, the outside diameter D1 of the protective element 23 and the outside diameter D2 of the magnet 20 correspond to the relation d> D1> D2. For example, d is 47.7 mm, D1 is 47.2 mm and D2 is 46.8 mm, wherein the lower diameter d of the stator 3 and the outside diameter D2 of the magnet 20 are equivalent to the sizes when the protective element 23 is not provided in the space and the outer diameter D1 of the protective element 23 is slightly smaller than the lower diameter d of the stator 3, so that at least the rotor 4 can be

  assembled through the inner bore of the stator 3.

  As a result, the space is reduced in size in comparison with the protective element 23 provided in space. The operation of the rotary electric machine according to the first embodiment will now be described. If a power supply with a pulse duration modulation is supplied from a control unit, not shown, to the connection terminal 16, the stator coil 13 located in the three-phase delta connection by the connection body coil 15 is energized, the shaft 18 pivots due to the electromagnetic action with the magnet 20 provided in the rotor 4 and the hydraulic pump of a hydraulic power steering, not shown is driven by its rotational force for

SR 22624 JP / JB

  assist a manual steering effort with its hydraulic pressure. A brushless motor for electro-hydraulic power steering is used at a voltage of 12 V, approximately 50 to 100 A and approximately 4500 rpm and should be small in size, inexpensive, and high performance, excellent especially in terms of security, response and silence. The rotary electric machine according to the first embodiment of the present invention is constituted in the above manner, in which the corner portion 22 on the outer peripheral face of the projection 21 is covered by a protective element 23, whereby the magnet 20 is more effectively protected from breakage or cracking as well as from floating under the effect of centrifugal force and the quality of the rotary electric machine is improved. In particular, ferrite can have a significant effect in that the corner portion 22 can easily be damaged or cracked at the time of assembly. The axial length of the magnet being substantially equal to the axial length of the yoke portion 19, the magnet 20 is easily put in place and the corner portion of the inside diameter is not damaged due to a length almost equal and the corner portion of the outer peripheral face is covered only by the protective element 23, whereby the magnet 20 is effectively protected from a break or crack although the part of angle of the inner diameter side of the magnet 20

SR 22624 JP / JB

  is likely to be damaged in the case where the magnet 20 is longer than the breech portion 19. The case where the axial length of the breech portion 19 would be almost equal to the axial length of the magnet 20, is in that the corner portion of the inner diameter side is not damaged. Furthermore, in the case where redan portion is provided in the corner portion 22 in the direction of the center of the shaft, and covered by a protective member 23, the cot is increased due to the redan portion and the new corner part is liable to be damaged, whereby if the redan part is not provided, it is possible

  to economically and effectively avoid the break.

  The protective element 23 is arranged in the projection 21, small and inexpensive, and easily assembled and the rotor 4 has a low rotational imbalance and inertia, whereby the eddy current is reduced, the performance increased and the rotary electric machine can be reduced in size. In particular, in the case where pulse duration modulation is performed, it results in a reduction of the eddy current loss. In addition, the space may be smaller than in the case where the protective member 23 is disposed in space, whereby the performance of the rotary electric machine is increased to reduce the size. The rotor 4 having axial movement limiting means for reducing the axial movement, the protective element 23 does not come into contact

with the stator 3.

SR 22624 JP / JB

  The breech portion 19 is integrally formed with the shaft 18 and can be machined with the shaft 18 and thereby increase productivity. There is also excellent concentricity between the shaft 18 and the outer peripheral face of the yoke portion 19. The magnet 20 being fixed on the outer peripheral face, the concentricity between the outer peripheral face of the magnet 20 and

  the protective element 23 may also be excellent.

  Also, the rotor 4 is easily mounted through the inner bore of the stator 3 and the thickness of the protective member 23 can be increased accordingly. Thus, the magnet 20 can be more effectively protected from breakage or cracking and from floating under the effect of centrifugal force. Due to the excellent concentricity, the space is further reduced, thus improving the performance of the rotating electric machine while reducing its size. The magnet 20 is composed of three magnetic pieces in the shape of a circular arc, each of which is magnetized in six poles. At the time of assembly, the magnet 20 can be effectively protected from a break or crack with respect to the case where the magnet 20 would be composed of six magnetic pieces in the shape of an arc of a circle as shown in FIG. Figure 5, because the magnet 20 is composed of a smaller number of parts. The magnet 20 is only cheaper and is easily assembled. Due to the arcuate circle shape, the magnet is easily manufactured, with good accuracy

SR 22624 JP / JB

  dimensional and the concentricity of the outer peripheral face of the magnet 20 after assembly is better. If the magnet 20 is composed of three parts, the angle on the arc is 120 degrees which does not create any manufacturing problem of the magnet 20 but the number of parts

  magnetic is determined according to this aspect.

  Since the magnet 20 is magnetized only after the protective element 23 is in place, there is no magnetic force until the protective element 23 is put in place, and there is no fragment of the magnet or foreign body stuck on the protective element

  23, and the protective element is highly reliable.

  It is therefore possible to effectively prevent the magnet from breaking or cracking in the process of assembling the magnetization treatment after with

disposed the protective element 23.

  The protective member 23, made of stainless, has a high strength and can effectively prevent the magnet 20 from breaking or cracking and floating under the effect of centrifugal force, even in a configuration in which the width of the projection 21 is relatively narrow. In addition, the protective element 23 is smaller, more easily machined and

  not expensive, without degradation of the performance.

  Since the protective element 23 has the shape of a cup covering the outer peripheral face of the projection 21 of the magnet 20 and the axial end face, it is possible to effectively prevent the magnet from deteriorating or cracks, whereby the protective element 23 is not moved to the

SR 22624 JP / JB

  stator 3 to contact the stator 3. Similarly, the strength of the protective member 23 is increased, it is possible to more effectively prevent the magnet 20 to float under the effect of centrifugal force. Since the protective element 23 is welded to the magnet 20, it is possible effectively to prevent the magnet from being damaged or to crack and to prevent the magnet 20 from floating under the effect of the centrifugal force. whereby the protective element 23 is not moved towards the stator 3 and does not come into contact with the stator 3. If the protective element 23 is made in the form of a cup, and welded by means of

  adhesives, its action is reinforced.

  The electric power steering motor must be a small and economical engine with high safety and high performance, and if the rotary electric machine according to the present invention is used, the electric steering motor

  appropriate assistance can be obtained.

  Embodiment 2 Referring to Figs. 6 and 7, a second embodiment of the present invention will now be described. Figure 6 is a sectional view of a rotor taken in the axial direction. FIG. 7A is a front view of a protective element and FIG. 7B is a sectional view of the protective element, taken along line B-B. The rotor 4 has a yoke portion 19 integrally formed with FIG. the shaft 18 and on which are fixed by adhesives magnets of

SR 22624 JP / JB

  ferrite 20 having a cylindrical sectional shape and inserted into the outer peripheral face of the yoke portion 19. Each magnet 20 has a projection 21 extending parallel to the inner peripheral surface of the stator core 10 and protruding axially from of any of the axial end faces of the stator core 10, an angle portion 22 of the outer peripheral face of the projection 21 being covered by the protective member 23. The protective member 23 has the shape shown in Figure 7 which is made by cutting a stainless tube with a thickness of 0.1 mm, for example. The protective element 23 is inserted into the projection 21 of the magnet 20 and fixed by adhesives. In addition, the magnet 20 is magnetized into six poles, after the protective element

23 be in place.

  The rotary electric machine according to the second embodiment of the present invention is constituted in the aforementioned manner and provides basically the same effects as the first embodiment. In particular, the magnet having a cylindrical shape, the number of parts is reduced and the mounting capabilities are improved. However, the cylindrical magnet has a higher cot. Since the protective element 23 is annular and economical, it is possible to effectively prevent the magnet 20 from breaking or cracking.

  and does not float under the effect of centrifugal force.

SR 22624 JP / JB

  Embodiment 3 Referring to Fig. 8, a third embodiment of the present invention will now be described. Figure 8 is a sectional view of a rotor taken in the axial direction. The rotor 4 has a yoke portion 19 formed integrally with the shaft 18 on which are attached by adhesives ferrite magnets 20 having a cylindrical sectional shape inserted into the face

  external device of the breech part 19.

  Each magnet 20 has a projection 21 extending parallel to the inner peripheral surface of the stator core 10 and protruding axially from any of the axial end faces of the stator core 10, a corner portion 22 of the outer peripheral face of the projection 21 being covered by the annular protective element 23. In addition, the magnet 20 has a concavity 24 in a space portion with the stator 3 a thermally contraction tube 25 being fixed in the cavity 24. The outer diameter of the thermal contraction tube 24 is less than or equal to the outer diameter D2 of the magnet 20. The axial length of the yoke portion 19 is slightly greater than the axial length of the

magnets 20.

  The rotary electric machine according to the third embodiment of the present invention is constituted in the aforementioned manner and provides basically the same effects as with the previous embodiments. In particular, because of the thermal contraction tube provided in addition,

SR 22624 JP / JB

  it is possible to more effectively prevent the magnet from floating under the effect of centrifugal force. Even if the magnet 20 is long in the axial direction, it is also possible to effectively prevent the magnet 20 from floating. In this embodiment the protection element 23 covering the corner portion 22 of the outer peripheral face of the projection 21 is made of stainless. However, the thermal contraction tube or the glass fiber impregnated with a thermosetting resin can be used even if the strength is lower. Various modifications can be made without departing from the

  field and spirit of the present invention.

  The rotary electric machine has been described with the use of a brushless motor. However, an electric motor or a dynamoteur can be used. As previously described, a rotary electric machine according to the first embodiment of the present invention comprises a stator core, a rotor disposed within the inner periphery of the stator core, and a magnet attached to the outer periphery of the rotor with a certain space of the inner peripheral face of the stator core, characterized in that the magnet has a protrusion projecting in the axial direction from the two axial end faces of the stator core and a protective element of a material non-magnetic disposed on the projection for covering at least a corner portion of the peripheral face

SR 22624 JP / JB

  outside of the projection. It is thus possible to effectively prevent the magnet from breaking or cracking and floating under the effect of centrifugal force, whereby the quality of the rotary electric machine is improved. The protective member may be reduced in size and thus be economical and easy to assemble with low imbalance and inertia whereby the eddy current loss is reduced, the improved performance and the rotating electric machine can be reduced in size. Moreover, the space can be reduced relative to the protective element disposed in space, whereby the performance of the rotary electric machine is improved and the rotary electric machine can

to be of reduced size.

  The rotary electric machine according to the second embodiment of the present invention is characterized in that the rotor has a magnet fixed on the outer peripheral face of the yoke portion integrally formed with a shaft. Thus, the rotor can be machined at the same time as the shaft, with high productivity and excellent concentricity between the shaft and the outer peripheral face of the yoke portion. Since the magnet is fixed on the outer peripheral face, the concentricity between the outer peripheral face of the magnet and the protective element is better achieved, whereby the rotor is easily assembled through the inner bore of the stator and the thickness of the protective element can be increased accordingly. So, can magnet 20 be more

SR 22624 JP / JB

  effectively protected from breakage or cracking and floating due to centrifugal force. Due to the excellent concentricity, the space is reduced even more to improve the performance of the rotary electric machine and the electric machine

  rotary can be reduced in size.

  The rotary electric machine according to the third embodiment of the present invention is characterized in that a plurality of magnets having an arcuate shape is fixed on the outer periphery of the rotor, each magnet being magnetized in multiple poles. Thus, the number of magnets is more restricted, it is possible to avoid more effectively that the magnet does not break or crack at the time of assembly, whereby the magnet has a lower edge and is easily assembled. Due also to its arcuate shape, the magnet is easily manufactured, with good dimensional accuracy whereby the concentricity of the outer peripheral face of

  the magnet after assembly is better.

  The rotary electric machine according to the fourth embodiment of the present invention is characterized in that the protective element is made of stainless steel. Thus, the protective member has high strength and can more effectively prevent the magnet from breaking or cracking and floating under the effect of centrifugal force at a generally small distance from the projection. In addition, the protective element is smaller, more easily machined and little

  expensive, without degradation of performance.

SR 22624 JP / JB

  The rotary electric machine according to the fifth embodiment of the present invention is characterized in that the protective element has the shape of a cup which covers the outer peripheral face of the protrusion of the magnet and an axial end face. . It is thus possible to prevent more effectively that the magnet does not break or crack and the protective element is not moved to the stator and does not come into contact with the stator. The protective element also has superior strength and can effectively prevent

  the magnet does not float under the effect of centrifugal force.

  The rotary electric machine according to the sixth embodiment of the present invention is characterized in that the protective element is welded to the magnet. It is thus possible to prevent more effectively that the magnet does not break or crack and floats under the effect of centrifugal force and the protective element is not moved to the stator

  and does not come into contact with the stator.

  The electric machine according to the seventh embodiment of the present invention is characterized in that the rotary electric machine is used for an electric power steering motor. Thus, is the rotary electric machine excellent in safety, response and quiet operation and is it perfectly suited for a power steering electric motor that is small in size, high performance and

cheap.

SR 22624 JP / JB

Claims (7)

  A rotary electric machine comprising a stator core (10); a rotor (4) disposed in the inner periphery of said stator core (10); and a magnet (20) fixed on the outer periphery of said rotor with a certain space of the inner peripheral face of said stator core (10); wherein: said magnet (20) has a protrusion (21) projecting in the axial direction from any of the faces of said stator core; and a protective member (23) of a non-magnetic material is disposed on said projection (21) to cover at least a corner portion (22) of said face   outer periphery of said projection.   The rotary electric machine according to claim 1, wherein said rotor (4) comprises a magnet (20) attached to the outer peripheral face of a breech portion   integrally formed with a shaft (18).   3. Rotating electric machine according to   claims 1 or 2, wherein:   a plurality of magnets (20) having an arcuate shape is fixed on the outer periphery of said rotor (4), each magnet being magnetized in several poles. SR 22624 JP / JB   4. Rotating electric machine according to one   any of claims 1 to 3, wherein   said protective element (23) is made of stainless steel. 5. Rotating electric machine according to one   any of claims 1 to 4, wherein   said protective member (23) is in the form of a cup which covers the outer peripheral face of said projection (21) of said magnet (20) and an axial end face.   6. Rotating electric machine according to one   any of claims 1 to 5, wherein:   said protective element (23) is welded to said magnet (20).   7. Rotating electric machine according to one   any of claims 1 to 6, wherein:   said rotary electric machine is used   for an electric power steering motor. SR 22624 JP / JB