Rotor of motor and motor provided with rotor of motor

Abstract

A rotor 10 of a motor 100 comprises: a rotary shaft 15 that extends in a vertical direction Z; a rotor core 20 that has a magnet insertion hole 30 extending in the vertical direction Z, is fixed to the rotary shaft 15, and is composed of a plurality of rotor-side electromagnetic steel plates 25 that are stacked in the vertical direction Z; and a magnet 40 that extends in the vertical direction Z and is inserted into the magnet insertion hole 30. The length Z1 of the rotor core 20 in the vertical direction Z is greater than the length Z2 of the magnet 40 in the vertical direction Z. A first distance between the lower end 40D of the magnet 40 and the lower end 20D of the rotor core 20 in the vertical direction Z is less than a second distance between the upper end 40U of the magnet 40 and the upper end 20U of the rotor core 20 in the vertical direction Z.

Description

Motor rotor and motor with motor rotor

[0001] The present invention relates to a motor rotor and a motor equipped with a motor rotor.

[0002] Conventionally, a motor rotor includes a rotating shaft, a rotor core made of a plurality of electromagnetic steel plates, magnets inserted into magnet insertion holes formed in the rotor core, and end plates provided at both axial ends of the rotor core to prevent the inserted magnets from protruding. For example, Patent Document 1 discloses a motor rotor equipped with end plates with holes that are provided at both ends of the rotor core to prevent the magnets from protruding and to prevent magnetic flux leakage, which is a phenomenon in which magnetic flux from the magnets leaks out toward the end plates without proceeding toward the stator.

[0003] Japanese Patent No. 6572914

[0004] However, in Patent Document 1, two types of end plates must be provided at both ends of the rotor core to prevent magnet protrusion and magnetic flux leakage from the magnet. This not only complicates assembly work but also increases the axial length of the motor's rotor, potentially resulting in an increased motor size. Another problem is that the end plates increase the rotor's weight. Furthermore, the increased weight due to the end plates can also increase the rotor's moment of inertia.

[0005] The present invention has been made in consideration of these points, and its object is to provide a motor rotor and a motor equipped with the motor rotor that can reduce the axial length, weight, and moment of inertia of the rotor while avoiding the complexity of assembly and suppressing magnetic flux leakage from the magnet.

[0006] The rotor of the motor of the present invention comprises a rotating shaft extending in a first direction, a rotor core having a magnet insertion hole extending in the first direction and fixed to the rotating shaft and composed of a plurality of electromagnetic steel plates stacked in the first direction, and a magnet extending in the first direction and inserted into the magnet insertion hole, wherein the length of the rotor core in the first direction is longer than the length of the magnet in the first direction, and a first distance in the first direction between an end of the magnet on one side in the first direction and an end of the rotor core on one side in the first direction is shorter than a second distance in the first direction between an end of the magnet on the other side in the first direction and an end of the rotor core on the other side in the first direction.

[0007] In the motor rotor according to the present invention, the first distance in the first direction between the end of the magnet on one side in the first direction and the end of the rotor core on one side in the first direction is shorter than the second distance in the first direction between the end of the magnet on the other side in the first direction and the end of the rotor core on the other side in the first direction. This aspect of the invention makes it possible to suppress magnetic flux leakage from at least the end of the magnet on the other side in the first direction. That is, magnetic flux leakage from the magnet can be suppressed even when a steel plate made of the same material as the electromagnetic steel plate constituting the rotor core is used on the other side of the rotor core on the first direction, and there is no need to provide a non-magnetic end plate. This allows the axial length of the rotor to be reduced, the weight of the rotor to be reduced, and the moment of inertia of the rotor to be reduced.

[0008] According to the present invention, it is possible to provide a motor rotor and a motor equipped with the motor rotor that can reduce the axial length, weight, and moment of inertia of the rotor while avoiding the complexity of assembly and suppressing magnetic flux leakage from the magnet.

[0009] FIG. 1 is a side view of a portion of a motor according to an embodiment. FIG. 2 is an enlarged cross-sectional view of a portion of a motor according to an embodiment. FIG. 3 is a cross-sectional view of a rotor of a motor according to an embodiment. FIG. 4 is a plan view of a first rotor side electromagnetic steel sheet according to an embodiment. FIG. 5 is a plan view of a second rotor side electromagnetic steel sheet according to an embodiment. FIG. 6 is a plan view of an end plate according to an embodiment. FIG. 7 is a bottom view showing a state in which an end plate is attached to a rotor core according to an embodiment.

[0010] Hereinafter, an embodiment of a motor according to the present invention will be described with reference to the drawings. It should be noted that the embodiment described here is not intended to limit the present invention in any way. Furthermore, the same reference numerals are used to designate components and parts that perform the same functions, and redundant descriptions will be omitted or simplified as appropriate.

[0011] Fig. 1 is a side view of a motor 100. As shown in Fig. 1, the motor 100 includes a rotor 10 and a stator 60 disposed radially outside the rotor 10.

[0012] As shown in FIG. 3 , the rotor 10 includes a rotating shaft 15 , a rotor core 20 , magnet insertion holes 30 , magnets 40 , end plates 50 , a first bearing 58 , and a second bearing 59 .

[0013] As shown in FIG. 3 , the rotating shaft 15 extends in the vertical direction Z. The vertical direction Z is an example of a first direction. Note that downward D is an example of one of the first directions, and upward U is an example of the other of the first directions. Note that the direction in which the rotating shaft 15 extends is not limited to the vertical direction Z. The length L1 of the rotating shaft 15 protruding downward D from the rotor core 20 is longer than the length L2 of the rotating shaft 15 protruding upward U from the rotor core 20. As shown in FIG. 1 , a portion of the rotating shaft 15 (here, the lower end 15B) protrudes downward D from the stator 60. An output member is attached to the lower end 15B of the rotating shaft 15. That is, the lower end 15B of the rotating shaft 15 is configured to allow an output member to be attached.

[0014] As shown in FIG. 3 , the rotor core 20 is an annular member centered on the axis 15C of the rotating shaft 15. The rotor core 20 is fixed to the rotating shaft 15. The rotor core 20 is composed of a plurality of rotor-side electromagnetic steel sheets 25 stacked in the vertical direction Z. The stacked rotor-side electromagnetic steel sheets 25 are fixed to one another by, for example, crimping, bonding, welding, or the like. The rotor-side electromagnetic steel sheets 25 are fixed to one another by, for example, crimping. The rotor core 20 has press-fit holes 28, magnet insertion holes 30, first holes 31 (see FIG. 4 ), second holes 32 (see FIG. 4 ), and through holes 33 (see FIG. 4 ). The press-fit holes 28, the magnet insertion holes 30, the first holes 31, the second holes 32, and the through holes 33 extend in the vertical direction Z.

[0015] As shown in FIG. 3 , the thickness T of one rotor-side electromagnetic steel sheet 25 in the vertical direction Z is, for example, 0.15 mm to 0.5 mm. The rotor-side electromagnetic steel sheet 25 is processed into a predetermined shape by punching using a press die. The rotor-side electromagnetic steel sheet 25 includes a plurality of first rotor-side electromagnetic steel sheets 25A and a second rotor-side electromagnetic steel sheet 25B stacked in the vertical direction Z. As will be described later, the second rotor-side electromagnetic steel sheet 25B has the same configuration as the first rotor-side electromagnetic steel sheet 25A, except that it does not include magnet insertion holes 30 and instead includes a fall-off prevention portion 38 (see FIG. 5 ). Therefore, the common parts between the first rotor-side electromagnetic steel sheet 25A and the second rotor-side electromagnetic steel sheet 25B will be described using the first rotor-side electromagnetic steel sheet 25A as an example.

[0016] 4, the first rotor side electromagnetic steel sheet 25A is formed in an annular shape and has a press-fit hole 28, a plurality of magnet insertion holes 30, a plurality of first holes 31, a plurality of second holes 32, and a plurality of through holes 33.

[0017] As shown in Fig. 3, the press-fit hole 28 is a hole into which the rotating shaft 15 is press-fitted. As shown in Fig. 4, the press-fit hole 28 is substantially circular in plan view (i.e., when viewed from the up-down direction Z). The press-fit hole 28 is formed with a plurality of recesses 28A recessed radially outward. The recesses 28A are arranged at equal intervals in the circumferential direction S. The recesses 28A are semicircular in plan view. Note that the shape of the recesses 28A is not limited to semicircular.

[0018] As shown in FIG. 3 , the magnet insertion hole 30 is a hole into which a magnet 40 is inserted. As shown in FIG. 4 , the magnet insertion hole 30 is located radially outward of the press-fit hole 28. The magnet insertion hole 30 includes a first magnet hole 30A and a second magnet hole 30B. The first magnet hole 30A is V-shaped in plan view, widening radially outward. The first magnet hole 30A has a first portion 30AA into which one magnet 40 is inserted and a second portion 30AB into which another magnet 40 is inserted. The first portion 30AA, the second portion 30AB, and the second magnet hole 30B are continuous. The second magnet hole 30B extends radially inward from the radially inner end of the first magnet hole 30A. The second magnet hole 30B is located on a line LN2 that passes through the center 28C of the press-fit hole 28 and the second hole 32. The line LN2 is an example of another line. The multiple magnet insertion holes 30 are arranged at equal intervals in the circumferential direction S. Note that the shape of the magnet insertion holes 30 and the number of magnets 40 inserted into the magnet insertion holes 30 are not limited to those described above. Also, Figure 4 shows a state in which two magnets 40 are inserted into only the first magnet hole 30A of one magnet insertion hole 30.

[0019] As shown in FIG. 4 , the first hole 31 is located radially outward from the press-fit hole 28. The first hole 31 is located radially inward from the magnet insertion hole 30. The first hole 31 is located on a straight line LN1 that passes through the center 28C of the press-fit hole 28 and the center 28AC of the recess 28A in the circumferential direction S. The first hole 31 is approximately trapezoidal in plan view. The length SA1 of the radially inner portion of the first hole 31 in the circumferential direction S is longer than the length SA2 of the radially outer portion of the first hole 31 in the circumferential direction S. The multiple first holes 31 are arranged at equal intervals in the circumferential direction S.

[0020] As shown in Figure 4, the second holes 32 are located radially outward from the press-fit holes 28. The second holes 32 are located radially inward from the magnet insertion holes 30. The second holes 32 are located radially between the press-fit holes 28 and the magnet insertion holes 30. The second holes 32 are generally trapezoidal in plan view. The length SB1 of the radially inner portion of the second holes 32 in the circumferential direction S is shorter than the length SB2 of the radially outer portion of the second holes 32 in the circumferential direction S. The multiple second holes 32 are arranged at equal intervals in the circumferential direction S.

[0021] As shown in FIG. 4 , the first holes 31 and the second holes 32 are alternately arranged in the circumferential direction S. Parts of the first holes 31 and parts of the second holes 32 overlap in the circumferential direction S. The radially inner end 31H of the first hole 31 is located radially inward of the radially inner end 32H of the second hole 32. The radially outer end 31J of the first hole 31 is located radially inward of the radially outer end 32J of the second hole 32. The length SA1 of the radially inner portion of the first hole 31 in the circumferential direction S is longer than the length SB1 of the radially inner portion of the second hole 32 in the circumferential direction S. The length SA2 of the radially outer portion of the first hole 31 in the circumferential direction S is shorter than the length SB2 of the radially outer portion of the second hole 32.

[0022] As shown in FIG. 4 , the through holes 33 are located radially outward of the press-fit holes 28. The through holes 33 are located on a straight line LN1. The through holes 33 are circular in a plan view. The through holes 33 overlap with the first holes 31 in the radial direction. The through holes 33 overlap with the second magnet holes 30B of the magnet insertion holes 30 in the circumferential direction S. The through holes 33 include a first through hole 33A and a second through hole 33B that are arranged point-symmetrically with respect to the center 28C of the press-fit hole 28. The multiple through holes 33 are arranged at equal intervals in the circumferential direction S. The through holes 33 and the magnet insertion holes 30 are arranged alternately in the circumferential direction S.

[0023] As shown in FIG. 4 , the rotor core 20 has an outer peripheral edge 20A having a plurality of arc portions 20H arranged in the circumferential direction S and a plurality of protrusions 20B located between adjacent arc portions 20H. The plurality of protrusions 20B are arranged at equal intervals in the circumferential direction S. The protrusions 20B are located on a straight line LN1. The protrusions 20B are located between adjacent magnet insertion holes 30 in the circumferential direction S. The plurality of arc portions 20H are arranged at equal intervals in the circumferential direction S. The arc portions 20H are located on a straight line LN2. Of the arc portions 20H, an outermost diameter portion 20HM having the largest radius centered on the center 28C of the press-fit hole 28 is located on the straight line LN2. In this embodiment, the radius of the outermost diameter portion 20HM and the radius of the protrusions 20B are the same, but they may be different.

[0024] As shown in FIG. 3 , the second rotor side electromagnetic steel sheet 25B is provided above the first rotor side electromagnetic steel sheet 25U, which is the uppermost of the stacked first rotor side electromagnetic steel sheets 25A. No end plate 50 is provided above the second rotor side electromagnetic steel sheet 25B above the first rotor side electromagnetic steel sheet 25U. That is, the second rotor side electromagnetic steel sheet 25B is exposed to the outside. As shown in FIG. 5 , the second rotor side electromagnetic steel sheet 25B has a press-fit hole 28, a plurality of first holes 31, a plurality of second holes 32, and a plurality of through holes 33. The second rotor side electromagnetic steel sheet 25B does not have a magnet insertion hole 30 (see FIG. 4 ). The second rotor side electromagnetic steel sheet 25B has a fall-out prevention portion 38 that prevents the magnets 40 inserted in the magnet insertion hole 30 from falling out (jumping out) from the magnet insertion hole 30. The fall-out prevention portion 38 overlaps the magnet insertion hole 30 in a plan view. The fall-out prevention portion 38 overlaps the entire magnet insertion hole 30 in a plan view.

[0025] As shown in FIG. 3 , the magnet 40 is inserted into the magnet insertion hole 30. The magnet 40 extends in the upward direction Z. The magnet 40 is formed in a flat plate shape. The magnet 40 is, for example, a permanent magnet. The magnet 40 is, for example, a rare earth magnet. The magnet 40 is, for example, a neodymium magnet containing neodymium (Nd), iron (Fe), and boron (B).

[0026] As shown in FIG. 3 , the length Z1 of the rotor core 20 in the vertical direction Z is longer than the length Z2 of the magnet 40 in the vertical direction Z. A first distance in the vertical direction Z between the lower end 40D of the magnet 40 and the lower end 20D of the rotor core 20 is shorter than a second distance in the vertical direction Z between the upper end 40U of the magnet 40 and the upper end 20U of the rotor core 20. The lower end 40D is an example of an end of the magnet 40 on one side in the first direction, and the upper end 40U is an example of an end of the magnet 40 on the other side in the first direction. The lower end 20D is an example of an end of the rotor core 20 on one side in the first direction, and the upper end 20U is an example of an end of the rotor core 20 on the other side in the first direction. The first distance is, for example, 2T or less (i.e., the thickness of the two laminated rotor-side electromagnetic steel sheets 25 in the vertical direction Z). The second distance is, for example, 3T to 6T. In this embodiment, the first distance is 0 and the second distance is 5T (i.e., the thickness in the vertical direction Z of the five stacked rotor side electromagnetic steel plates 25), but the first distance and the second distance are not limited to this.

[0027] As shown in FIG. 3 , the end plate 50 is provided below D of the rotor core 20. The end plate 50 is provided below the first rotor side electromagnetic steel sheet 25D, which is located at the lowest D among the multiple first rotor side electromagnetic steel sheets 25A of the rotor core 20. The end plate 50 is fixed to the rotating shaft 15 by, for example, press fitting. Note that the end plate 50 may be fixed to the rotating shaft 15 by press fitting the rotor core 20 into the rotating shaft 15. In this case, the end plate 50 is not press fitted into the rotating shaft 15. As shown in FIG. 7 , the end plate 50 is formed in a circular plate shape. The diameter of the end plate 50 is smaller than the diameter of the rotor side electromagnetic steel sheet 25. The end plate 50 overlaps the entire magnet insertion hole 30 in a plan view. The end plate 50 prevents the magnets 40 inserted in the magnet insertion hole 30 from falling out (jumping out) from below D of the magnet insertion hole 30. The end plate 50 is made of a non-magnetic material (e.g., stainless steel (e.g., SUS303)). The vertical thickness H of the end plate 50 (see FIG. 3) is thicker than the thickness T of one rotor-side electromagnetic steel plate 25. As shown in FIG. 6, the end plate 50 is formed with a press-fit hole 52 and a plate hole 54. The press-fit hole 52 is a hole into which the rotating shaft 15 is press-fit. The plate hole 54 is a hole into which an attachment jig (not shown) is inserted. The plate hole 54 includes a first plate hole 54A and a second plate hole 54B that are arranged point-symmetrically with respect to the center 52C of the press-fit hole 52. As shown in FIG. 7, the plate hole 54 overlaps with the through hole 33 in a plan view. The plate hole 54 does not overlap with the magnet insertion hole 30. The first plate hole 54A overlaps with the first through hole 33A in a plan view, and the second plate hole 54B overlaps with the second through hole 33B in a plan view. The diameter of the press-fit hole 52 is larger than the diameter of the plate hole 54.

[0028] As shown in FIG. 1 , the stator 60 houses the rotor 10. The stator 60 supports the rotor 10 for free rotation. As shown in FIG. 2 , the stator 60 includes a stator core 70 and a plurality of windings 75 wound around the stator core 70. The stator core 70 is an annular member centered on the axis 15C (see FIG. 3 ) of the rotating shaft 15. The stator core 70 is fixed to a cover (not shown) of the motor 100. The stator core 70 is composed of a plurality of stator-side electromagnetic steel sheets 80 stacked in the vertical direction Z. The stator-side electromagnetic steel sheets 80 are processed into a predetermined shape by stamping using a press die. As shown in FIG. 1 , connection portions 75A between the plurality of windings 75 are located above the rotating shaft 15 (the other side in the vertical direction Z). The plurality of windings 75 may be star-connected or delta-connected. 2 , the difference between the length Z1 of the rotor core 20 in the up-down direction Z and the length Z3 of the stator core 70 in the up-down direction Z is equal to or less than the thickness 2T in the up-down direction Z of the two laminated rotor-side electromagnetic steel sheets 25. In this embodiment, the length Z1 of the rotor core 20 in the up-down direction Z is equal to the length Z3 of the stator core 70 in the up-down direction Z.

[0029] 1, the motor 100 includes a rotation sensor 90 that detects the rotation angle of the rotating shaft 15. The rotation sensor 90 is provided on the side of the upper end 15A of the rotating shaft 15. The rotation sensor 90 is fixed to the stator 60. Examples of the rotation sensor 90 include a resolver, an encoder, and an MR sensor.

[0030] As shown in FIG. 3 , the first bearing 58 and the second bearing 59 are rolling bearings. The first bearing 58 and the second bearing 59 are, for example, ball bearings. The first bearing 58 is a load-side bearing. The first bearing 58 rotatably supports the rotating shaft 15. The second bearing 59 is a non-load-side bearing. The second bearing 59 rotatably supports the upper end 15A of the rotating shaft 15. The first bearing 58 and the second bearing 59 are fixed to the stator 60 (see FIG. 1 ).

[0031] As described above, with the rotor 10 of the motor 100 of this embodiment, the first distance in the vertical direction Z between the lower end 40D of the magnet 40 and the lower end 20D of the rotor core 20 is shorter than the second distance in the vertical direction Z between the upper end 40U of the magnet 40 and the upper end 20U of the rotor core 20. According to the above aspect, it is possible to suppress magnetic flux leakage of the magnet 40 from at least the upper end 40U of the magnet 40. That is, even if a steel plate made of the same material as the first rotor-side electromagnetic steel plate 25A constituting the rotor core 20 (e.g., the second rotor-side electromagnetic steel plate 25B) is used at the upper end 20U of the rotor core 20, magnetic flux leakage of the magnet 40 can be suppressed. Furthermore, since there is no need to provide an end plate 50 made of a non-magnetic material, the axial length of the rotor 10 (i.e., the length in the vertical direction Z) can be reduced (shortened), and the weight of the rotor 10 can be reduced, and the moment of inertia of the rotor 10 can be reduced.

[0032] The rotor 10 of the motor 100 of this embodiment is provided with end plates 50 made of a non-magnetic material that are provided below the rotor core 20 and that prevent the magnets 40 inserted into the magnet insertion holes 30 from falling out from below. According to the above aspect, because the end plates 50 made of a non-magnetic material are provided below the rotor core 20, it is possible to prevent the magnets 40 from protruding in the axial direction (here, the up-down direction Z) and also to suppress magnetic flux leakage from the magnets 40.

[0033] In the rotor 10 of the motor 100 of this embodiment, the first distance is equal to or less than the thickness 2T in the vertical direction Z of the two laminated rotor-side electromagnetic steel sheets 25. According to the above aspect, it is possible to concentrate heavy objects in the vertical direction Z downward.

[0034] The rotor 10 of the motor 100 of this embodiment is configured so that an output member can be attached to the lower end 15B of the rotating shaft 15. According to the above aspect, heavy objects can be concentrated downward in the vertical direction Z.

[0035] In the rotor 10 of the motor 100 of this embodiment, the length L1 of the rotating shaft 15 that protrudes downward from the rotor core 20 is longer than the length L2 of the rotating shaft 15 that protrudes upward from the rotor core 20. According to the above aspect, heavy objects can be concentrated downward in the vertical direction Z.

[0036] The motor 100 of this embodiment includes a rotation sensor 90 that is provided at the upper end 15A of the rotating shaft 15 and detects the rotation angle of the rotating shaft 15. According to the above-described aspect, magnetic flux leakage from the upper end 40U of the magnet 40 is suppressed, thereby preventing malfunction of the rotation sensor 90.

[0037] In motor 100 of this embodiment, connection portions 75A between the multiple windings 75 of stator 60 are located above rotating shaft 15. According to the above aspect, magnetic flux leakage from upper ends 40U of magnets 40 is suppressed, thereby reducing overcurrent loss in the wires of windings 75 (reducing overcurrent in the wires due to the magnetic flux of magnets 40).

[0038] In the motor 100 of this embodiment, the difference between the length Z1 of the rotor core 20 in the up-down direction Z and the length Z3 of the stator core 70 in the up-down direction Z is equal to or less than the thickness 2T in the up-down direction Z of the two laminated rotor-side electromagnetic steel sheets 25. According to the above aspect, leakage of the magnetic flux of the magnet 40 and the field flux of the winding 75 in the up-down direction Z can be suppressed.

[0039] In the motor 100 of this embodiment, the length Z1 of the rotor core 20 in the vertical direction Z is equal to the length Z3 of the stator core 70 in the vertical direction Z. According to the above aspect, leakage of the magnetic flux of the magnet 40 and the field flux of the winding 75 in the vertical direction Z can be more reliably suppressed.

[0040] The above describes a preferred embodiment of the present invention. However, the above embodiment is merely an example, and the present invention can be embodied in various other forms. In the above embodiment, the rotor 10 includes the end plate 50 provided below the rotor core 20. However, the rotor 10 may include another end plate above the rotor core 20 that has a similar configuration to the end plate 50.

[0041] In the above-described embodiment, the radially inner end 31H of the first hole 31 is located radially inward of the radially inner end 32H of the second hole 32, and the radially outer end 31J of the first hole 31 is located radially inward of the radially outer end 32J of the second hole 32. However, this is not limiting. For example, the radially inner end 31H of the first hole 31 may be located radially outward of the radially inner end 32H of the second hole 32, and the radially outer end 31J of the first hole 31 may be located radially outward of the radially outer end 32J of the second hole 32.

[0042] In the above-described embodiment, the length SA1 in the circumferential direction S of the radially inner portion of the first hole 31 is longer than the length SB1 in the circumferential direction S of the radially inner portion of the second hole 32, and the length SA2 in the circumferential direction S of the radially outer portion of the first hole 31 is shorter than the length SB2 in the circumferential direction S of the radially outer portion of the second hole 32, but this is not limiting. For example, the length SA1 in the circumferential direction S of the radially inner portion of the first hole 31 may be shorter than the length SB1 in the circumferential direction S of the radially inner portion of the second hole 32, and the length SA2 in the circumferential direction S of the radially outer portion of the first hole 31 may be longer than the length SB2 in the circumferential direction S of the radially outer portion of the second hole 32.

[0043] DESCRIPTION OF SYMBOLS 10 Rotor 15 Rotating shaft 20 Rotor core 25 Rotor-side electromagnetic steel plate 28 Press-fit hole 28C Center 28A Recess 28AC Center 30 Magnet insertion hole 30A First magnet hole 30B Second magnet hole 31 First hole 32 Second hole 33 Through hole 33A First through hole 33B Second through hole 40 Magnet 50 End plate 52 Press-fit hole 54 Plate hole 54A First plate hole 54B Second plate hole 60 Stator 70 Stator core 75 Winding 75A Wiring connection portion 90 Rotation sensor 100 Motor

Claims

1. A motor rotor comprising: a rotating shaft extending in a first direction; a rotor core having magnet insertion holes extending in the first direction and fixed to the rotating shaft and composed of a plurality of electromagnetic steel plates stacked in the first direction; and magnets extending in the first direction and inserted into the magnet insertion holes, wherein a length of the rotor core in the first direction is longer than a length of the magnets in the first direction, and a first distance in the first direction between an end of the magnet on one side in the first direction and an end of the rotor core on one side in the first direction is shorter than a second distance in the first direction between an end of the magnet on the other side in the first direction and an end of the rotor core on the other side in the first direction.

2. A rotor of a motor as described in claim 1, comprising an end plate provided on one side of the rotor core in the first direction, which prevents the magnets inserted into the magnet insertion holes from falling out from the one side in the first direction, and which is made of a non-magnetic material.

3. A rotor for a motor according to claim 1, wherein the first distance is equal to or less than a thickness of the two laminated electromagnetic steel sheets in the first direction.

4. A rotor for a motor according to claim 1, wherein an output member can be attached to one end of said rotating shaft in said first direction.

5. A rotor for a motor as described in claim 1, wherein the length by which the rotating shaft protrudes from the rotor core to one side in the first direction is longer than the length by which the rotating shaft protrudes from the rotor core to the other side in the first direction.

6. A motor comprising: a motor rotor according to any one of claims 1 to 5; and a rotation sensor provided on the side of the other end of the rotating shaft in the first direction, for detecting the rotation angle of the rotating shaft.

7. A motor comprising: a rotor of a motor according to any one of claims 1 to 5; and a stator supporting said rotor for free rotation, said stator comprising a stator core and a plurality of windings wound around said stator core, and connection portions between the plurality of windings are located on the other side of said rotating shaft in said first direction.

8. A motor comprising: a rotor of a motor as defined in any one of claims 1 to 5; and a stator supporting the rotor for free rotation, wherein the stator comprises a stator core and a plurality of windings wound around the stator core, and the difference between the length of the rotor core in the first direction and the length of the stator core in the first direction is equal to or less than the thickness in the first direction of two stacked electromagnetic steel sheets.

9. The motor according to claim 8, wherein the length of said rotor core in said first direction is equal to the length of said stator core in said first direction.

Images