The present disclosure relates to a brushless motor and a rotor.
Japanese Patent No. 4468033 discloses a brushless motor for a variable valve timing apparatus as one example of a conventional motor for a position control apparatus arranged in a vehicle engine room. The brushless motor is provided with a rotor including a rotor core, through which a bore extends in the axial direction, and a field magnet, which is inserted into and fixed to the bore.
In a brushless motor like the one described above, the field magnet is inserted into and fixed to the bore that extends through the rotor core in the axial direction. Thus, the field magnet is easily affected by the ambient environments. For example, when the temperature in the vehicle engine room becomes high, the field magnet is easily demagnetized (irreversible temperature change). When the temperature is high, the magnetic force of the field magnet becomes weak. To cope with this, the current flowing through the coils of a stator may be increased. However, if the current is increased, the field magnet is further easily demagnetized (irreversible temperature change).
It is an object of the present disclosure to provide a brushless motor and a rotor capable of resisting demagnetization (irreversible temperature change) of a field magnet even when, for example, the temperature in a vehicle engine room becomes high.
To achieve the above object, a first aspect of the present disclosure is a brushless motor for a position control apparatus arranged in a vehicle engine room and includes a rotor. The rotor includes a first rotor core, a second rotor core, and a field magnet. The first rotor core includes a plurality of first magnetic pole portions arranged in a circumferential direction. The second rotor core includes a plurality of second magnetic pole portions arranged in a circumferential direction. The field magnet is arranged between the first rotor core and the second rotor core in an axial direction. The first magnetic pole portions function as first magnetic poles and the second magnetic pole portions function as second magnetic poles when the field magnet is magnetized in the axial direction.
A second aspect of the present disclosure is a brushless motor including a rotor and a stator. The rotor includes a rotation shaft, a first rotor core, a second rotor core, and a field magnet. The first rotor core includes a disk-shaped first core base that rotates integrally with the rotation shaft around the rotation shaft. A plurality of first claw-shaped magnetic poles are arranged at equal intervals on an outer circumferential surface of the first core base. Each of the first claw-shaped magnetic poles includes a first basal portion, which projects radially outward, and a first distal portion, which bends from the first basal portion and extends in an axial direction. The second rotor core includes a disk-shaped second core base that rotates integrally with the rotation shaft around the rotation shaft, and a plurality of second claw-shaped magnetic poles arranged at equal intervals on an outer circumferential surface of the second core base. Each of the second claw-shaped magnetic poles includes a second basal portion, which projects radially outward, and a second distal portion, which bends from the second basal portion and extends in an axial direction. The second claw-shaped magnetic poles are arranged between adjacent ones of the first claw-shaped magnetic poles in a circumferential direction. The field magnet rotates integrally with the rotation shaft around the rotation shaft. The field magnet is arranged between the first core base and the second core base. The field magnet is magnetized in the axial direction so that each of the first claw-shaped magnetic poles functions as a first magnetic pole and each of the second claw-shaped magnetic poles functions as a second magnetic pole. The stator includes a stator core and windings. The stator core is arranged at an outer side of the rotor and including a plurality of teeth located at equal intervals in the circumferential direction. Each of the teeth includes a radially inner circumferential surface opposed to radially outer circumferential surfaces of the first and second claw-shaped magnetic poles. The windings are wound as concentrated windings around each of the teeth. The windings generate a rotating field when voltage is applied to the windings. The first and second claw-shaped magnetic poles are formed in a range satisfying θ1≦θα<(360/n)−θL, where the number of magnetic poles of the rotor is represented by n, an opening angle of the radially outer circumferential surfaces of the first and second claw-shaped magnetic poles is represented by θα, an opening angle of the radially inner circumferential surface of each of the teeth is represented by θ1, and an opening angle between a circumferential end of the first distal portion and a circumferential end of the second distal portion in adjacent ones of the first and second claw-shaped magnetic poles is represented by θL when a circumferential length between the circumferential end of the first distal portion and the circumferential end of the second distal portion is equal to a distance of an air gap between the stator and the rotor.
A third aspect of the present disclosure is a brushless motor including rotor and a stator. The rotor includes a rotation shaft, a first rotor core, a second rotor core, and a field magnet. The first rotor core includes a disk-shaped first core base that rotates integrally with the rotation shaft around the rotation shaft, and a plurality of first claw-shaped magnetic poles arranged at equal intervals on an outer circumferential surface of the first core base. Each of the first claw-shaped magnetic poles includes a first basal portion, which projects radially outward, and a first distal portion, which bends from the first basal portion and extends in an axial direction. The second rotor core includes a disk-shaped second core base that rotates integrally with the rotation shaft around the rotation shaft, and a plurality of second claw-shaped magnetic poles arranged at equal intervals on an outer circumferential surface of the second core base. Each of the second claw-shaped magnetic poles includes a second basal portion, which projects radially outward, and a second distal portion, which bends from the second basal portion and extends in an axial direction. The second claw-shaped magnetic poles are arranged between adjacent ones of the first claw-shaped magnetic poles in a circumferential direction. The field magnet rotates integrally with the rotation shaft around the rotation shaft. The field magnet is arranged between the first core base of the first rotor core and the second core base of the second rotor core. The field magnet is magnetized in the axial direction so that each of the first claw-shaped magnetic poles functions as a first magnetic pole and each of the second claw-shaped magnetic poles functions as a second magnetic pole. The stator includes a stator core and windings. The stator core is arranged at an outer side of the rotor and includes a plurality of teeth located at equal intervals in the circumferential direction. Each of the teeth includes a radially inner circumferential surface opposed to radially outer circumferential surfaces of the first and second claw-shaped magnetic poles. The windings are wound as concentrated windings around each of the teeth. The windings generate a rotating field when voltage is applied to the windings. The first and second claw-shaped magnetic poles are formed in a range satisfying θL≦θβ<360/n−θ1, where the number of magnetic poles of the rotor is represented by n, an opening angle between a circumferential end of the first distal portion and a circumferential end of the second distal portion in adjacent ones of the first and second claw-shaped magnetic poles is represented by θβ, an opening angle of a radially inner circumferential surface of the teeth is represented by θ1, and the opening angle θβ is represented by θL when a circumferential length between the circumferential end of the first distal portion and the circumferential end of the second distal portion is equal to a distance of an air gap between the stator and the rotor.
A fourth aspect of the present disclosure is a rotor including a rotation shaft, a first rotor core, a second rotor core, a field magnet, and a reinforcement. The first rotor core includes a substantially disk-shaped first core base having a central portion fixed to the rotation shaft, and a plurality of first claw-shaped magnetic poles arranged at equal intervals on an outer circumferential surface of the first core base. Each of the first claw-shaped magnetic projects radially outward and extends in an axial direction. The second rotor core includes a substantially disk-shaped second core base having a central portion fixed to the rotation shaft, and a plurality of second claw-shaped magnetic poles arranged at equal intervals on an outer circumferential surface of the second core base. Each of the second claw-shaped magnetic poles projects radially outward and extends in an axial direction, the first and second core bases are opposed to each other. The first and second claw-shaped magnetic poles are alternately arranged in a circumferential direction. The field magnet is arranged between the first and second core bases in the axial direction. The field magnet is magnetized in the axial direction so that the first claw-shaped magnetic poles function as first magnetic poles and the second claw-shaped magnetic poles function as second magnetic poles. The reinforcement reinforces the first rotor core and the second rotor core. The reinforcement is formed integrally with or discretely from the first rotor core and the second rotor core.
The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:
A first embodiment of a brushless motor will now be described with reference to
As shown in
As shown in
As shown in
As shown in
As shown in
The first rotor core 31 includes a substantially disk-shaped first core base 31a and a plurality of (four in this embodiment) first claw-shaped magnetic poles 31b as first magnetic pole portions. The first claw-shaped magnetic poles 31b are provided on an outer portion of the first core base 31a and arranged in equal intervals. Each of the first claw-shaped magnetic poles 31b projects radially outward and extends in the axial direction.
The second rotor core 32 includes a substantially disk-shaped second core base 32a having the same shape as that of the first rotor core 31 and a plurality of second claw-shaped magnetic poles 32b serving as second magnetic pole portions. The second claw-shaped magnetic poles 32b are provided on an outer portion of the second core base 32a and arranged in equal intervals. Each of the second claw-shaped magnetic poles 32b projects radially outward and extends in its axial direction. The second rotor core 32 is coupled to the first rotor core 31 such that the second claw-shaped magnetic poles 32b are arranged between adjacent ones of the first claw-shaped magnetic poles 31b in a circumferential direction. The annular magnet 33 is arranged (sandwiched) between the first core base 31a and the second core base 32a in the axial direction. In this embodiment, the first and second core bases 31a and 32a are fixed to the annular magnet 33 using an adhesive.
As shown in
In this embodiment, the coupled first and second core bases 31a and 32a and annular magnet 33 are configured such that the diameter is four times or greater than the axial length. The diameter of the assembled object is set to be 100 mm or less.
As shown in
Next, the operation of the brushless motor 11 having the above-described configuration will be described.
For example, when control is performed to change the valve timing in accordance with the operation condition of the vehicle when the vehicle is being driven, a three-phase drive current is supplied from the control circuit S to the windings 19 thereby generating a rotating field. Then, the rotor 21 is rotated and driven, and the variable valve timing apparatus 3 changes the valve timing (rotation phase of cam shaft relative to crankshaft of the engine 2).
Next, advantages of the first embodiment will be described.
(1) The variable valve timing apparatus 3 arranged in the vehicle engine room 1 includes the brushless motor 11. The annular magnet 33 of the rotor 21 in the brushless motor 11 is arranged between the first rotor core 31 and the second rotor core 32 in the axial direction. Since the annular magnet 33 is less likely to be affected by the ambient environment, even if the temperature in the vehicle engine room 1 becomes high, the annular magnet 33 is less likely to be demagnetized (irreversible temperature change). This allows for the execution of stable position control, that is, valve timing varying.
(2) The first and second claw-shaped magnetic poles 31b and 32b, which serve as the first and second magnetic pole portions, project radially outward from the outer portions of the substantially disk-shaped first and second core bases 31a and 32a, and extend in the axial direction to cover a radially outer surface of the annular magnet 33. Hence, the annular magnet 33 is further less likely to be affected by the ambient environment. Therefore, even if the temperature in the vehicle engine room 1 becomes high, the annular magnet 33 is further less likely to be demagnetized (irreversible temperature change).
(3) The annular magnet 33 is arranged radially inward from the outer portions of the disk-shaped first and second core bases 31a and 32a of the first and second rotor cores 31 and 32. Hence, the annular magnet 33 is further less likely to be affected by the ambient environment. Therefore, even if the temperature in the vehicle engine room 1 becomes high, the annular magnet 33 is further less likely to be demagnetized (irreversible temperature change).
(4) The number of poles of the rotor 21 is set to 2×n (wherein, n is a natural number), and the number of teeth 17a of the stator 16 is set to 3×n. Hence, a lowest common multiple becomes small. This allows for many first and second claw-shaped magnetic poles 31b and 32b to be opposed to the teeth 17a and allows for the detent torque to be increased. Hence, when the motor is not driven, it is possible to reduce rotation of the rotor 21 caused by vibration in the vehicle engine room 1.
The first embodiment may be modified as follows.
In the first embodiment, the annular magnet 33 is arranged radially inward from the outer portions of the disk-shaped first and second core bases 31a and 32a of the first and second rotor cores 31 and 32. However, this may be changed.
For example, the outer diameter of the annular magnet 33 may be the same as the first and second core bases 31a and 32a as shown in
In the rotor 21 of the first embodiment, only the annular magnet 33 is a permanent magnet. Instead, the rotor may have other permanent magnets.
For example, as shown in
In the first embodiment, the first magnetic pole portions and the second magnetic pole portions are the first and second claw-shaped magnetic poles 31b and 32b. Instead, the first magnetic pole portions and the second magnetic pole portions may be changed to magnetic pole portions having other shapes.
For example, as shown in
Cross-sectional shapes of the first and second claw-shaped magnetic poles 31b and 32b (first magnetic pole portions and second magnetic pole portions) in the first embodiment in a direction perpendicular to the radially outer surface do not have to be circles extending about the center axis of the rotation shaft 22 of the rotor 21.
For example, the cross-sectional shapes may be changed as shown in
In this case, distances between the stator 16 (teeth 17a) and the surfaces of the first and second claw-shaped magnetic poles 31b and 32b that are rotated are varied.
Hence, as the distances are varied, a magnetic field is largely varied. This variation becomes a load during rotation and increases the detent torque. Hence, rotation of the rotor 21 by vibration in the vehicle engine room 1 when the motor is not driven is reduced.
Although the number of poles of the rotor 21 is set to “eight”, and the number of the teeth 17a of the stator 16 is set to “twelve” in the first embodiment, the numbers may be changed. For example, the number of poles of the rotor 21 may be set to “four”, and the number of the teeth 17a of the stator 16 may be set to “six”. Alternatively, the number of poles of the rotor 21 may be set to “six”, and the number of the teeth 17a of the stator 16 may be set to “nine”. At least one of the following conditions does not have to be satisfied. That is, the condition that the number of poles of the rotor 21 is set to 2×n (wherein, n is a natural number), and the condition that the number of teeth 17a of the stator 16 is set to 3×n.
In the first embodiment, the present disclosure is applied to the brushless motor 11 for the variable valve timing apparatus 3, but the present disclosure may be applied to a brushless motor for other position control apparatus (e.g., throttle valve control apparatus) arranged in the vehicle engine room 1.
A second embodiment of the brushless motor will now be described with reference to
As shown in
The stator 102 includes a cylindrical stator core 110, and an outer circumferential surface of the stator core 110 is fixed to an inner surface of the motor housing 101. A plurality of teeth 111 are formed on an inner side of the stator core 110 in the axial direction. The teeth 111 are arranged in the circumferential direction with the same pitch. The teeth 111 extend radially inward. Each of the teeth 111 is a T-shaped tooth, and an inner circumferential surface 111a thereof in the radial direction is an arcuate surface formed by axially extending an arc of a circle extending about the center axis O of the rotation shaft 103.
Slots 112 are formed between the teeth 111. In the second embodiment, the number of the teeth 111 is twelve, and the number of the slots 112 is also twelve like the teeth 111. Three-phase windings, namely, U-phase windings 113u, V-phase windings 113v, and W-phase windings 113w are wound as concentrated windings around the twelve teeth 111 sequentially in the circumferential direction.
Here, as shown in
Three-phase power-supply voltage is applied to the wound windings 113u, 113v, and 113w to form a rotating field in the stator 102, and the rotor 104 fixed to the rotation shaft 103 arranged in the stator 102 is rotated in the forward direction (clockwise direction in
As shown in
As shown in
The length of the fixing cylinder 115 in the axial direction is greater than that of the field magnet 140. The first and second rotor cores 120 and 130 and the field magnet 140 are combined with each other so that the field magnet 140 is arranged between the first and second rotor cores 120 and 130. In the second embodiment, the lengths of the first and second rotor cores 120 and 130 and the field magnet 140 in the axial direction conform to the length of the fixing cylinder 115.
As shown in
Both end surfaces 122a and 122b in the circumferential direction of the first claw-shaped magnetic pole 122 including the first basal portion 123 and the first magnetic pole portion 124 are radially extending flat surfaces. The angle of each of the first claw-shaped magnetic poles 122 in the circumferential direction extending about the center axis O of the rotation shaft 103, i.e., the angle between the two end surfaces 122a and 122b in the circumferential direction is set to be smaller than the angle of the distance between the first claw-shaped magnetic poles 122 which are adjacent to each other in the circumferential direction. Here, as shown in
The cross-section of a radially outer circumferential surface f1a of the first magnetic pole portion 124 in a direction perpendicular to the axis is an arc of a circle extending about the center axis O of the rotation shaft 103.
As shown in
The second claw-shaped magnetic poles 132 extend in the axial direction. Here, a portion of each of the second claw-shaped magnetic poles 132 that projects radially outward from the outer circumferential surface 131c of the second core base 131 is referred to as the second basal portion 133, and a distal end of the second claw-shaped magnetic pole 132 that is bent in the axial direction is referred to as the second magnetic pole portion 134.
Circumferential end surfaces 132a and 132b of the second claw-shaped magnetic pole 132 including the second basal portion 133 and the second magnetic pole portion 134 are flat surfaces that extend in the radial direction. The angle of each of the second claw-shaped magnetic poles 132 in the circumferential direction extending about the center axis O of the rotation shaft 103, i.e., the angle between the two circumferential end surfaces 132a and 132b is set to be smaller than an angle of a distance between the second claw-shaped magnetic poles 132 that are adjacent to each other in the circumferential direction. Here, the angle of the second claw-shaped magnetic pole 132 in the circumferential direction extending about the center axis O of the rotation shaft 103 is referred to as the first rotor-side opening angle θα like the first rotor core 120.
The cross-section of a radially outer circumferential surface f2a of the second magnetic pole portion 134 in a direction perpendicular to the axis is an arc of a circle extending about the center axis O of the rotation shaft 103.
The second claw-shaped magnetic poles 132 are respectively arranged between the corresponding first claw-shaped magnetic poles 122. Here, the second rotor core 130 is coupled to the first rotor core 120 such that the field magnet 140 (see
As shown in
As shown in
The outer diameter of the field magnet 140 conforms to the outer diameters of the first and second core bases 121 and 131, and the thickness of the field magnet 140 is set to have a predetermined thickness.
More specifically, as shown in
As shown in
Therefore, the rotor 104 of the second embodiment is a rotor of a so-called Lundell-type structure using the field magnet 140. In the rotor 104, the first claw-shaped magnetic poles 122 which become north poles and the second claw-shaped magnetic poles 132 which become south poles are alternately arranged in the circumferential direction. The number of magnetic poles of the rotor 104 is eight.
As shown in
The first back surface auxiliary magnet 151 has a sectoral and substantially box-shaped cross-section in a direction perpendicular to the axis of the first back surface auxiliary magnet 151. To reduce magnetic flux leakage at this location, the first back surface auxiliary magnet 151 is magnetized in the radial direction such that the pole of a portion of the auxiliary magnet 151 that abuts against the back surface f1b of the first magnetic pole portion 124 becomes a north pole which is the same as the first claw-shaped magnetic pole 122, and the pole of a portion of the auxiliary magnet 151 that abuts against the second core base 131 becomes a south pole which is the same as the second core base 131.
As shown in
The second back surface auxiliary magnet 152 has a sectoral and substantially box-shaped cross-section in a direction perpendicular to the axis of the second back surface auxiliary magnet 152. To reduce magnetic flux leakage at this location, the second back surface auxiliary magnet 152 is magnetized in the radial direction such that the pole of a portion of the auxiliary magnet 152 that abuts against the back surface f2b of the second magnetic pole portion 134 becomes a south pole which is the same as the second claw-shaped magnetic pole 132, and the pole of a portion of the auxiliary magnet 152 that abuts against the first core base 121 becomes a north pole which is the same as the first core base 121.
First and second interpolar magnets 153 and 154 are arranged and fixed between the first claw-shaped magnetic pole 122 where the first back surface auxiliary magnet 151 is arranged and the second claw-shaped magnetic pole 132 where the second back surface auxiliary magnet 152 is arranged in the circumferential direction. The first and second interpolar magnets 153 and 154 have sectoral and substantially box-shaped cross-sections in directions perpendicular to their axes.
More specifically, the first interpolar magnet 153 is arranged between a flat surface, formed by a circumferential end surface 122a of the first claw-shaped magnetic pole 122 and a circumferential end surface of the first back surface auxiliary magnet 151, and a flat surface, formed by a circumferential end surface 132b of the second claw-shaped magnetic pole 132 and a circumferential end surface of the second back surface auxiliary magnet 152. The cross-section of a radially outer circumferential surface 153a of the first interpolar magnet 153 in a direction perpendicular to the axis of the radially outer circumferential surface 153a has an arc shape of a circle extending about the center axis O of the rotation shaft 103. The radially outer circumferential surface 153a and the radially outer circumferential surfaces f1a and f2a of the first magnetic pole portion 124 and the second magnetic pole portion 134 are flush with each other.
As shown in
In the same manner, the second interpolar magnet 154 is arranged between a flat surface, formed by the circumferential end surface 122b of the first claw-shaped magnetic pole 122, a circumferential end surface of the first back surface auxiliary magnet 151, and a flat surface, formed by a circumferential end surface 132a of the second claw-shaped magnetic pole 132 and a circumferential end surface of the second back surface auxiliary magnet 152. The cross-section of a radially outer circumferential surface 154a of the second interpolar magnet 154 in a direction perpendicular to the axis of the radially outer circumferential surface 154a has an arc shape of a circle extending about the center axis O of the rotation shaft 103. The radially outer circumferential surface 154a and the radially outer circumferential surfaces f1a and f2a of the first magnetic pole portion 124 and the second magnetic pole portion 134 are flush with each other.
Here, as shown in
The first and second interpolar magnets 153 and 154 are magnetized in the circumferential direction such that they have the same magnetic poles as the first and second claw-shaped magnetic poles 122 and 132 (first claw-shaped magnetic pole becomes a north pole and second claw-shaped magnetic pole becomes a south pole).
Next, variations in the output of the brushless motor 11 when changing the first and second rotor-side opening angles θα and θβ with respect to the first and second teeth-side opening angles θ1 and θ2 will be discussed.
An experiment was carried out to study variations in the output of the brushless motor 11.
In the brushless motor 11, the number of the teeth 111 was twelve, and the number n of magnetic poles of the rotor 104 was eight. The first teeth-side opening angle θ1 was fixed and the first rotor-side opening angle θα was changed within a range from θα=0° to θα=360/n=45° to study variations in the output torque.
The horizontal axis shows the first rotor-side opening angle θα. The vertical axis shows, in percentage, the output torque ratio (%) using the output torque of the brushless motor 11 as a reference (100%) when the first rotor-side opening angle θα was the same as the first teeth-side opening angle θ1 (θα=θ1).
The following is apparent from
0<θα<θ1
If the first rotor-side opening angle θα is increased from θα=0 to θα=θ1, the output torque also increases as the first rotor-side opening angle θα increases.
It is considered that this is because an increase in the area of the radial outer circumferential surface f1a (f2a) of the first magnetic pole portion 124 (second magnetic pole portion 134) opposed to inner circumferential surfaces 111a of the tooth 111 relatively increases the output torque.
θ1≦θα≦θ1+2×θ2
Until the first rotor-side opening angle θα increases from θα=θ1 to θα=θ1+(2×θ2), the value of the output torque (%) is maintained at 100% or greater.
It is considered that this is because the output torque is in a saturated state since the radially outer circumferential surface f1a (f2a) of the first magnetic pole portion 124 (second magnetic pole portion 134) becomes greater than an area of the inner circumferential surfaces 111a and the radially outer circumferential surface f1a (f2a) does not extend over the inner circumferential surfaces 111a of the three teeth 111.
θ1+2×θ2<θα<(360/n)−θL
Until the first rotor-side opening angle θα reaches θα=(360/n)−θL=45−θL from θα=θ1+(2×θ2), the output torque (%) gradually decreases.
It is considered that this is because the radially outer circumferential surface f1a (f2a) of the first magnetic pole portion 124 (second magnetic pole portion 134) is gradually opposed to the inner circumferential surfaces 111a of the three teeth 111 at the same time, and a magnetic circuit that short-circuits the three-phase magnetic flux is generated and reduces the output torque.
Here, θL is the angle of the second rotor-side opening angle θβ when circumferential lengths (arc lengths) of the radially outer circumferential surfaces 153a and 154a of the first and second interpolar magnets 153 and 154 become equal to a distance L of an air gap between the stator 102 and the rotor 104.
(360/n)−θL≦θα≦(360/n)
If the first rotor-side opening angle θα becomes equal to or greater than θα=(360/n)−θL, the output torque (%) suddenly decreases to 90% or less.
It is considered that this is because the distance (arc length) between the first magnetic pole portion 124 and the second magnetic pole portion 134 becomes shorter than the distance L of the air gap, the magnetic flux is short-circuited between the first magnetic pole portion 124 and the second magnetic pole portion 134, i.e., the magnetic flux of the rotor 104 (magnetic pole portion) is not effectively guided to the stator 102 (teeth 111), and the output torque of the brushless motor 11 is suddenly decreased.
From a result of the experiment, it was found that if the first rotor-side opening angle θα was in the range of θ1≦θα<(360/n)−θL, the brushless motor 11 could be driven.
If the first rotor-side opening angle θα is set to a value between θ1≦θα≦θ1+(2×θ2), high output torque can be obtained.
Especially, if the first rotor-side opening angle θα is set to θα=θ1+(2×θ2), as the rotor 104 rotates, the first magnetic pole portion 124 (second magnetic pole portion 134) separates from the teeth 111 to which the first magnetic pole portion 124 (second magnetic pole portion 134) is opposed and at the same time, the first magnetic pole portion 124 (second magnetic pole portion 134) approaches an adjacent tooth 111. Hence, if the first rotor-side opening angle θα is set to θα=θ1+(2×θ2), cogging torque can be reduced. Further, since the first and second interpolar magnets 153 and 154 can be reduced in size, costs of the magnets can be reduced.
If the first rotor-side opening angle θα is determined, the second rotor-side opening angle θβ is directly determined. That is, the second rotor-side opening angle θβ is obtained by the following equation:
θβ=(360/n)−(θ1+2×θ2)
From this reason, when the first rotor-side opening angle θα is within a range of θ1≦θα≦θ1+(2×θ2), the second rotor-side opening angle θβ is within the following range:
(360/n)−(θ1+2×θ2)≦θβ≦(360/n)−θ1
At this time, the number n of magnetic poles is eight.
Therefore, θβ=(360/8)−(θ1+2×θ2)=45−(θ1+2×θ2).
Here, the following (Example 1) and (Example 2) will be described based on numeric values of the first teeth-side opening angle θ1.
When the first teeth-side opening angle θ1 is 27° and the second teeth-side opening angle θ2 is 3°, the first rotor-side opening angle θα becomes as follows.
That is, from θα=θ1=27° and θα=θ1+(2×θ2)=33°, when the first rotor-side opening angle θα is within a range of 27°≦θα≦33°, high output torque can be obtained.
At this time, if viewed from the second rotor-side opening angle θβ, when θα=θ1=27°, θβ becomes 18°, and when θα=θ1=33°, θβ becomes 12°. That is, when the second rotor-side opening angle θβ is in a range of 12°≦θβ≦18°, high output torque can be obtained.
When the first rotor-side opening angle θα is (360/8)−θL, the second rotor-side opening angle θβ becomes θL.
For example, when the first teeth-side opening angle θ1 is 28° and the second teeth-side opening angle θ2 is 2°, the first rotor-side opening angle θα becomes as follows.
From θα=θ1=28° and θα=θ1+(2×θ2)=32°, when the first rotor-side opening angle θα is within a range of 28°≦θα≦32°, high output torque can be obtained.
If this situation is viewed from the second rotor-side opening angle θβ, when θα=θ1=28°, θβ becomes 17°, and when θα=θ1=32°, θβ becomes 13°. That is, when the second rotor-side opening angle θβ is within a range of 13 °≦θβ≦17°, high output torque can be obtained.
When the first rotor-side opening angle θα is θα=(360/8)−θL, the second rotor-side opening angle θβ becomes θβ=θL.
Next, an assembling method of the rotor 104 of the brushless motor 11 having the above-described configuration will be described.
First, the fixing cylinder 115 is inserted into the through bore 141 of the field magnet 140 to a predetermined position. At this insertion position, an outer circumferential surface of the fixing cylinder 115 and an inner circumferential surface of the through bore 141 of the field magnet 140 are adhered and fixed to each other using a non-magnetic adhesive.
Next, the fixing cylinder 115 is inserted into the through bore 120a of the first rotor core 120 (first core base 121) such that the opposing surface 121a of the first core base 121 and the side surface 140a of the field magnet 140 are opposed to each other. The opposing surface 121a of the first core base 121 and the side surface 140a of the field magnet 140 are adhered and fixed to each other using magnetic adhesive, an inner circumferential surface of the through bore 120a of the first core base 121 and an outer circumferential surface of the fixing cylinder 115 are adhered and fixed to each other using non-magnetic adhesive. At this time, an annular first end surface 115a of the fixing cylinder 115 closer to the first core base is flush with the non-facing surface 121b of the first core base 121.
Next, the fixing cylinder 115 is inserted into the through bore 130a of the opposing surface 131a of the second core base 131 and the second rotor core 130 (second core base 131) such that the opposing surface 131a of the second core base 131 and the side surface 140b of the field magnet 140 are opposed to each other.
While adjusting a relative position in the circumferential direction with the first rotor core 120 which is fixed first, the opposing surface 131a of the second core base 131 and the side surface 140b of the field magnet 140 are adhered and fixed to each other using a magnetic adhesive, and an inner circumferential surface of the through bore 130a of the second core base 131 and the outer circumferential surface of the fixing cylinder 115 are adhered and fixed to each other using non-magnetic adhesive.
At this time, an annular second end surface 115b of the fixing cylinder 115 closer to the second core base is flush with the non-facing surface 131b of the second core base 131.
As a result, the first and second rotor cores 120 and 130 are adhered and fixed to the field magnet 140, and the first rotor core 120, the second rotor core 130 and the field magnet 140 are adhered and fixed to the fixing cylinder 115.
A module in which the first rotor core 120, the second rotor core 130, the field magnet 140 and the fixing cylinder 115 are integrally formed is coupled to the rotation shaft 103.
More specifically, the first rotor core 120, the second rotor core 130 and the field magnet 140 are fixed to the fixing cylinder 115, the rotation shaft 103 is press-fitted into the fixing cylinder 115 up to a predetermined position, and the fixing cylinder 115 is fixed to the rotation shaft 103. When the rotation shaft 103 is press-fitted into the fixing cylinder 115, the fixing cylinder 115 and the rotation shaft 103 are first arranged in line so that the center axis O of the rotation shaft 103 and the center axis of the fixing cylinder 115 are aligned with each other.
Next, in a state where one of openings of the fixing cylinder 115, e.g., the second end surface 115b is arranged on the rotation shaft 103, the annular first end surface 115a of the fixing cylinder 115 is pressed in the axial direction using a cylindrical jig. If the first end surface 115a of the fixing cylinder 115 is pressed by the cylindrical jig, the rotation shaft 103 is press-fitted into one of the openings of the fixing cylinder 115.
If the fixing cylinder 115 is press-fitted into the rotation shaft 103 to a predetermined position, a press-fitting and fixing operation of the module including the first rotor core 120, the second rotor core 130, the field magnet 140, and the fixing cylinder 115 into the rotation shaft 103 is completed, and the assembling operation of the rotor 104 is completed.
Next, the operation of the brushless motor 11 configured as described above will be described.
In the brushless motor 11, three-phase power-supply voltage is applied to the three-phase windings 113u, 113v, and 113w which are wound around the teeth 111 of the stator core 110. This forms a rotating field in the stator 102, and the rotor 104 fixed to the rotation shaft 103 arranged in the stator 102 is rotated based on the rotating field.
At this time, if the first rotor-side opening angle θα is set in a range of θ1≦θα≦θ1+(2×θ2), the radially outer circumferential surface f1a (f2a) of first magnetic pole portion 124 (second magnetic pole portion 134) straddles the inner circumferential surfaces 111a of the three teeth 111, and the radially outer circumferential surface f1a (f2a) is not opposed to the inner circumferential surfaces 111a of the three teeth 111. Therefore, by setting the first rotor-side opening angle θα in the range of θ1≦θαθ1+(2×θ2), high output torque can be obtained.
Further, if the first rotor-side opening angle θα is set to θα=θ1+(2×θ2), as the rotor 104 rotates, the first magnetic pole portion 124 (second magnetic pole portion 134) which is opposed to one of the teeth 111 separates from that tooth 111. At the same time, the first magnetic pole portion 124 (second magnetic pole portion 134) approaches an adjacent tooth 111. Hence, if the first rotor-side opening angle θα is set to θα=θ1+(2×θ2), cogging torque can be reduced.
The first rotor-side opening angles θα of the first and second magnetic pole portions 124 and 134 configuring the first and second claw-shaped magnetic poles 122 and 132 are set in a range of θ1≦θα<(360/n)−θL. Thus, output torque capable of driving the brushless motor 11 can be obtained.
In the rotor 104, the module composed of the first rotor core 120, the second rotor core 130, the field magnet 140 and the fixing cylinder 115 is fixed to the rotation shaft 103 through the fixing cylinder 115. Therefore, it becomes easy to assemble the rotor 104 into the rotation shaft 103 of the module.
Further, the axial length of the fixing cylinder 115 is set to be the same as the axial lengths of the first rotor core 120, the second rotor core 130, and the field magnet 140, which are combined so that the field magnet 140 is arranged between the first rotor core 120 and the second rotor core 130. Thus, the module is rigidly connected to the rotation shaft 103, and it is possible to prevent vibration and noise of the rotor 104 caused by rotation. The fixing cylinder 115 having a long axial length is made of non-magnetic material. This prevents magnetic flux of the field magnet 140 from leaking toward the rotation shaft as a leakage magnetic flux.
When the rotation shaft 103 is press-fitted into and fixed to the module, the field magnet 140 is adhered to the fixing cylinder 115. Thus, when the rotation shaft 103 is press-fitted into the module, a load is not applied directly to the field magnet 140. This avoids damages inflicted to the field magnet 140 by a load.
Further, the first and second rotor cores 120 and 130 are adhered and fixed to the field magnet 140 using magnetic adhesive. Thus, magnetic resistance between the first and second rotor cores 120 and 130 and the field magnet 140 can be reduced. Further, it is possible to easily and accurately adjust relative positions of the first magnetic pole portion 124 of the first rotor core 120 and the second magnetic pole portion 134 of the second rotor core 130 in the circumferential direction. As a result, the brushless motor 11 generates smooth rotation.
Further, the first and second rotor cores 120 and 130 and the field magnet 140 are adhered and fixed to the fixing cylinder 115 using a non-magnetic adhesive. Thus, it is possible to prevent a leakage magnetic flux by the non-magnetic adhesive together with the rotation shaft 103 and the fixing cylinder 115 which are made of non-magnetic material.
Next, advantages of the second embodiment in addition to advantage (1) of the first embodiment will be described below.
(5) In the second embodiment, the first rotor-side opening angle θα is set in the range of θ1≦θα<(360/n)−θL. Thus, it is possible to obtain output torque capable of driving the brushless motor 11.
If the first rotor-side opening angle θα is set in the range of θ1≦θα≦θ1+(2×θ2), it is possible to realize the brushless motor 11 with high output torque. Especially, if the first rotor-side opening angle θα is set to θα=θ1+(2×θ2), it is possible to realize the brushless motor 11 that reduces cogging torque.
(6) In the second embodiment, the first rotor core 120, the second rotor core 130, and the field magnet 140 are coupled the fixing cylinder 115 and modularized. Therefore, the rotor 104 may be formed just by press-fitting and fixing the rotation shaft 103 into the fixing cylinder 115. Therefore, the assembling operation of the rotor 104 becomes extremely easy. Further, since the field magnet 140 is adhered to the fixing cylinder 115, a load produced when press fitting the rotation shaft 103 is not applied directly to the field magnet 140. Therefore, the field magnet 140 is not damaged during the coupling operation.
Further, the axial length of the fixing cylinder 115 is set to the same axial length as the first rotor core 120, the second rotor core 130, and the field magnet 140 combined with each other so that the field magnet 140 is arranged between the first rotor core 120 and the second rotor core 130. Therefore, the first and second rotor cores 120 and 130 and the field magnet 140 are fixed to the rotation shaft 103 through the fixing cylinder 115 to form a rigid structure, and it is possible to prevent vibration and noise of the rotor 104 caused by rotation.
(7) In the second embodiment, the first and second rotor cores 120 and 130 are adhered and fixed to the field magnet 140. Thus, it is possible to easily and accurately adjust the relative positions of the first magnetic pole portion 124 of the first rotor core 120 and the second magnetic pole portion 134 of the second rotor core 130 in the circumferential direction. As a result, the brushless motor 11 produces smooth rotation.
(8) In the second embodiment, the first and second rotor cores 120 and 130 are adhered and fixed to the field magnet 140 using a magnetic adhesive. Thus, magnetic resistance between the first and second rotor cores 120 and 130 and the field magnet 140 can be reduced.
(9) In the second embodiment, the first and second rotor cores 120 and 130 and the field magnet 140 are adhered and fixed to the fixing cylinder 115 using a non-magnetic adhesive. Hence, magnetic flux leakage is inhibited by the non-magnetic adhesive together with the rotation shaft 103 and the fixing cylinder 115, which are made of non-magnetic material.
The second embodiment may be modified as follows.
Although the rotor 104 is provided with the first and second back surface auxiliary magnets 151 and 152 in the second embodiment, the first and second back surface auxiliary magnets 151 and 152 may be omitted.
Although the rotor 104 is provided with the first and second interpolar magnets 153 and 154 in the second embodiment, the first and second interpolar magnets 153 and 154 may be omitted. The first and second back surface auxiliary magnets 151 and 152 may also be omitted.
Although the rotor 104 is fixed to the rotation shaft 103 through the fixing cylinder 115 in the second embodiment, the fixing cylinder 115 may be omitted. For example, the rotation shaft 103 may be press-fitted into and fixed to the first and second rotor cores 120 and 130. At that time, the field magnet 140 is sandwiched and fixed between the first and second rotor cores 120 and 130.
In the second embodiment, the axial length of the fixing cylinder 115 is set to the same axial length as the first rotor core 120, the second rotor core 130, and the field magnet 140, which are combined so that the field magnet 140 is arranged between the first rotor core 120 and the second rotor core 130. Instead, as shown in
A third embodiment of the brushless motor including a rotor will now be described with reference to
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
In the third embodiment, the through bores 40, which extend from one axial side to the other axial side in the first rotor core 31, the second rotor core 32, and the annular magnet 33, function as reinforcements together with the rivets 51 inserted into the through bores 40.
In the motor 11 configured as described above, when three-phase drive current is supplied to the windings 19 through an external power-supply circuit (not shown), a magnetic field is generated in the stator 16 for rotating the rotor 21, and the rotor 21 is rotated and driven.
Next, the operation of the above motor will be described.
In the motor 11 of the third embodiment, the rivets 51 are inserted into the through bores 40 formed in the first and second rotor cores 31 and 32 and the annular magnet 33 configuring the rotor 21 and in this state, the rivets 51 are swaged. Thus, movements of the bottom 25c and the lid 25b of the rotor-side housing 25a in the axial direction is restricted. In this manner, the first and second rotor cores 31 and 32 and the annular magnet 33 are rigidly fixed to each other. Since the rivets 51 are made of non-magnetic material, short circuiting of a magnetic flux of the annular magnet 33 is reduced.
Next, advantages of the third embodiment in addition to advantage (1) of the first embodiment will be described below.
(10) The rivets 51, which serve as the fixing members, are inserted into the through bores 40, which serve as the communication portions, and the rivets 51 fix the first and second rotor cores 31 and 32 and the annular magnet 33, which serves as the field magnet. Thus, it is possible to further rigidly fix the rotor cores 31 and 32 and the annular magnet 33 to each other.
(11) The plurality of through bores 40 arranged in a circle are formed at positions where the annular magnet 33 and the first and second rotor cores 31 and 32 are overlapped in the axial direction. By swaging the rivets 51 inserted into the through bores 40, the first and second rotor cores 31 and 32 are fixed to the annular magnet 33. By fixing the first and second rotor cores 31 and 32 to the annular magnet 33 in this manner, separation of the first and second rotor cores 31 and 32 and the annular magnet 33 by vibration or the like is limited, and the first and second rotor cores 31 and 32 are further rigidly fixed to the annular magnet 33. Since an adhesive or the like that would be melted by heat is not used, heat resistance may be enhanced.
(12) Since the rivets 51 are made of non-magnetic material, it is possible to reduce short circuit of a magnetic flux of the annular magnet 33, and output of the rotor 21 can be enhanced.
(13) By forming the plurality of through bores 40 at equal angular intervals in the circumferential direction, preferable weight balance can be obtained. Hence, vibration can be reduced.
(14) Since the through bores 40 are formed at radially central portions of the radially outer surface 33a of the annular magnet 33 and the inner surface 33c of the insertion bore 33b, the distance from the through bore 40 to the radially outer surface 33a and the distance from the through bore 40 to the inner surface 33c of the insertion bore 33b may be equal. This limits cracking of the annular magnet 33 that would be caused when forming the through bores 40.
(15) The back surface auxiliary magnet 34 and the interpolar magnet 35 serving as the auxiliary magnets are provided in a gap formed in the back surfaces 32i of the claw-shaped magnetic poles 31b and 32b and in the gap between the first claw-shaped magnetic pole 31b and the second claw-shaped magnetic pole 32b in the circumferential direction. Due to the magnets 34 and 35, leakage of magnetic flux from the gap of the rotor 21 is limited.
(16) The plate-shaped lid 25b, serving as the sandwiching portion, and the plate-shaped bottom 25c, serving as the sandwiching portion, sandwich the first and second rotor cores 31 and 32. The simple structure restricts movement of the lid 25b and the bottom 25c (rotor-side housing 25a) in the axial direction. This ensures the fastening of the lid 25b to the bottom 25c.
(17) By providing the cylindrical portion 25d as the annular wall, scattering of the magnets 33 to 35 is limited.
(18) The lid 25b and the bottom 25c serving as the sandwiching portions are made of non-magnetic material. This reduces short circuiting of a magnetic flux of the magnets 33 to 35 and increases the output of the rotor 21.
The third embodiment may be modified as follows.
In the third embodiment, the rivets 51 are arranged in the through bores 40 which are provided at 90° intervals from one another in the circumferential direction. Instead, the number of through bores 40 and the number of rivets 51 paired with the through bores 40 may be freely changed. For example, the number of through bores 40 and the number of rivets 51 paired with the through bores 40 may be two as shown in
Although the first and second rotor cores 31 and 32 include four claw-shaped magnetic poles 31b and 32b in the third embodiment, the invention is not limited to this configuration. As shown in
Although the first and second rotor cores 31 and 32, the annular magnet 33 and the like are accommodated in the rotor case 25 in the third embodiment, the rotor case 25 may be omitted as shown in
Although the back surface auxiliary magnet 34 and the interpolar magnet 35 are provided as the auxiliary magnets in the third embodiment, the auxiliary magnets may be omitted as shown in
The rotor 21 and the magnet fixing member 41 accommodating the sensor magnet 42 are fixed to each other using the rivets 51 in the third embodiment. Instead, for example, when the magnet fixing member 41 is arranged at a position separated from the rotor case 25, the rivets 51 do not have to be used.
The first and second rotor cores 31 and 32 and the annular magnet 33 are fixed to each other by swaging the rivets 51 as the fixing members in the third embodiment.
Instead, as shown in
The through bores 40 are formed at radially central portions of the radially outer surface 33a of the annular magnet 33 and the inner surface 33c of the insertion bore 33b in the third embodiment. Instead, as shown in
The through bores 40 are provided at the positions where the first and second rotor cores 31 and 32 and the annular magnet 33 are overlapped with each other in the axial direction in the third embodiment. Instead, as shown in
Like the annular magnet 33, the first notches 40a configuring the through bores 40 are also formed in the first and second rotor cores 31 and 32. In this case, the back surface auxiliary magnet 34 serving as the auxiliary magnet is also fixed by the fixing members provided in the through bores 40.
In the configuration shown in
In
The through bores 40 are provided with fixing members (rivets 51 and the fixing portions 52) in the third embodiment and the modifications of the third embodiment. Instead, for example, it is possible to employ a configuration including eight through bores 40, four provided with the fixing members such as the rivets 51 and the fixing portions 52, and the remaining four through bores 40 used for positioning in the circumferential direction.
The through bores 40, which are formed in the first rotor core 31, the second rotor core 32, and the annular magnet 33, serves as the insertion portions in the third embodiment. Instead, as shown in
The entire rotor cores 31 and 32 are covered with the rotor-side housing 25a and the lid 25b in which the bottom 25c and the cylindrical portion 25d are integrally formed as the sandwiching portions in the third embodiment. Instead, as shown in
A fourth embodiment of the brushless motor will now be described.
As shown in
The stator 212 has an armature core 215 including a plurality of teeth extending radially inward, and a segment conductor winding (SC winding) 216 wound around the teeth of the armature core 215. The stator 212 is fixed to an inner circumferential surface of the housing 211. The rotor 213 is rotatably arranged in the stator 212, and a rotation shaft 220 of the rotor 213 is rotatably supported by bearings 217a and 217b held by a bottom central portion of the housing 211 and a central portion of the end plate 214.
A circuit accommodating box 219 accommodating a circuit substrate 218 is mounted on an outer side of a bottom of the housing 211. A power supply circuit and the like are configured on the circuit substrate 218. The circuit substrate 218 and the winding 216 of the stator 212 are connected to each other. A rotating field is generated at the stator 212 when power is supplied from the circuit substrate 218 to the winding 216, and the rotor 213 is rotated and driven.
As shown in
The first rotor core 221 is configured by annularly arranging a plurality of (five in this embodiment) core segments 222 having the same shapes in the circumferential direction. Each of the core segments 222 is formed by punching an oriented magnetic steel sheet. The core segment 222 includes a basal portion 223, which is substantially sectoral as viewed from the axial direction, and a first claw-shaped magnetic pole 224 (salient-pole) formed on a circumferentially central portion of an outer circumferential surface of the basal portion 223.
The basal portion 223 of each of the core segments 222 is annularly arranged in the circumferential direction and configures a disk-shaped core base 225. Circumferential end surfaces of the basal portions 223 (boundaries of basal portions 223 which are adjacent to each other in the circumferential direction) extend straight along a radial direction with respect to an axial direction of the rotation shaft 220. The boundaries of the basal portions 223 which are adjacent to each other in the circumferential direction are arranged at equal intervals in the circumferential direction in the first rotor core 221.
A connecting convex portion 223a (connecting portion) is formed on one circumferential end surface of each of the basal portions 223, and a connecting concave portion 223b (connecting portion) is formed in the other circumferential end surface of the basal portion 223. The connecting convex portion 223a and the connecting concave portion 223b are substantially circular in shape as viewed from the axial direction, and the connecting convex portion 223a of each of the basal portions 223 is fitted into the connecting concave portion 223b of the circumferential adjacent basal portion 223. Thus, the adjacent basal portions 223 are engaged with each other in the circumferential direction and are connected to each other so that they do not separate from each other. A shaft fixing bore 225a is formed in a radially center portion of the disk-shaped core base 225 including the basal portion 223. The rotation shaft 220 is inserted into and fixed to the shaft fixing bore 225a by an adhesive or the like.
Only one first claw-shaped magnetic pole 224 is formed on one core segment 222, and five first claw-shaped magnetic poles 224 are formed on the entire first rotor core 221 at equal intervals in the circumferential direction. The first claw-shaped magnetic pole 224 includes a projection 224a projecting radially outward from an outer circumferential surface of the basal portion 223, and a claw 224b extending axially toward one side from a projecting distal end of the projection 224a. The claw 224b is formed by bending the projection 224a at a right angle, and an outer circumferential surface of the claw 224b is opposed to the stator 212.
The second rotor core 231 has the same configuration as that of the first rotor core 221. That is, the second rotor core 231 includes a plurality of core segments 232, which has basal portions 233 (including connecting convex portions 233a and connecting concave portions 233b) and second claw-shaped magnetic poles 234 (including projections 234a and claws 234b). Each of the core segments 232 has the same shape as that of the core segment 222 of the first rotor core 221.
In the fourth embodiment, the connecting convex portion 223a (233a) and the connecting concave portion 223b (233b) formed in each of the core segments 222 (232) to connect circumferential adjacent core segments 222 (232) to each other function as reinforcements.
The first and second rotor cores 221 and 231 are arranged such that the first and second claw-shaped magnetic poles 224 and 234 are opposed to each other. The first and second rotor cores 221 and 231 are combined with each other such that the first and second claw-shaped magnetic poles 224 and 234 are alternately arranged at equal intervals in the circumferential direction, and such that predetermined gaps are formed between adjacent first and second claw-shaped magnetic poles 224 and 234. The first and second rotor cores 221 and 231 are arranged such that the field magnet 241 is held between the core bases 225 and 235 of the first and second rotor cores 221 and 231 in the axial direction.
The field magnet 241 is annular and has a central portion in which a shaft insertion bore 241a is formed. The rotation shaft 220 is inserted into the shaft insertion bore 241a and the shaft fixing bores 225a and 235a of the core bases 225 and 235 to fix the rotation shaft 220 to the core bases 225 and 235. An outer circumferential surface of the field magnet 241 is opposed to back surfaces (inner circumferential surfaces) of the claw-shaped magnetic poles 224 and 234 through a gap in the radial direction. The field magnet 241 is magnetized in the axial direction, and is arranged such that one axial side surface of the field magnet 241 which abuts against the first rotor core 221 becomes a north pole and one axial side surface of the field magnet 241 which abuts against the second rotor core 231 becomes a south pole. That is, due to the field magnet 241, the first claw-shaped magnetic pole 224 functions as the north pole and the second claw-shaped magnetic pole 234 functions as the south pole. A neodymium magnet is used as the field magnet 241.
A manufacturing method and operation of the first and second rotor cores 221 and 231 in the fourth embodiment will now be described with reference to
As shown in
Next, as shown in
Next, the first claw-shaped magnetic poles 224 of the plurality of core segment raw materials 252 are bent at right angles into the same direction. Thus, the claw 224b (see
Through the above-described procedures, the first rotor core 221 in which the first claw-shaped magnetic poles 224 are arranged on the outer portion of the disk-shaped core base 225 at equal intervals in the circumferential direction as shown in
According to such a manufacturing method, since the core segments 222 and 232 (core segment raw materials 252) are punched out from the magnetic steel sheet 251 when arranged in a straight line, waste of the magnetic steel sheet 251 is reduced as compared with when the rotor core is not divided and the cores are punched out as from an annularly arranged state. This increases yield. The core bases 225 and 235 of the rotor cores 221 and 231 are divided at equal intervals for the claw-shaped magnetic poles 224 and 234. Hence, it becomes easy to uniformly distribute the magnetic flux to the claw-shaped magnetic poles 224 and 234. As a result, output may be enhanced and torque pulsation may be reduced.
Next, advantages of the fourth embodiment in addition to advantage (1) of the first embodiment will be described.
(19) The rotor cores 221 and 231 are configured by annularly arranging, in the circumferential direction, the core segments 222 and 232 respectively including the claw-shaped magnetic poles 224 and 234 (salient-poles). Thus, the core segments 222 and 232 (core segment raw material 252) arranged on a straight line are punched out from the magnetic steel sheet 251, and the core segments 222 and 232 are annularly arranged in the circumferential direction. This allows for the rotor cores 221 and 231 to be formed. Hence, waste of the magnetic steel sheet 251 can be reduced as compared with when the rotor core is not divided in the circumferential direction and punched out from the steel sheet. As a result, the yield is enhanced. Since the core bases 225 and 235 of the rotor cores 221 and 231 are divided at equal intervals for the claw-shaped magnetic poles 224 and 234, it becomes easy to uniformly distribute magnetic flux to the claw-shaped magnetic poles 224 and 234. As a result, output may be enhanced, and torque pulsation may be reduced.
(20) The salient-poles of the rotor cores 221 and 231 are configured by the claw-shaped magnetic poles 224 and 234 that extend in the axial direction of the rotor 213. Hence, an opposing surface of the salient-pole opposed to the stator 212 in the radial direction may be widened in the axial direction of the rotor 213. This enhances the output.
(21) The claw-shaped magnetic poles 224 and 234 are bent in the axial direction of the rotor 213. It is possible to easily form the claw-shaped magnetic poles 224 and 234 that extend in the axial direction just by bending a portion of the core segment raw material 252 which is punched out from the magnetic steel sheet 251.
(22) The connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b, which connect the circumferentially adjacent basal portions 223 and 233 to each other, are formed on and in the basal portions 223 and 233 of the core segments 222 and 232. Thus, the adjacent basal portions 223 and 233 can be rigidly connected to each other such that they do not separate from each other. As a result, the quality of the motor may be improved. Further, since there is no need to separately provide a connecting member for integrally connecting the core segments 222 and 232 to each other, an increase in the number of parts may be limited.
(23) The punching direction is set such that the direction of magnetic characteristics of the oriented magnetic steel sheet that configures the core segments 222 and 232 conforms to a radial direction of the rotor 213. This configuration makes it easy for magnetic flux to flow between the basal portions 223 and 233 and the claw-shaped magnetic poles 224 and 234. This configuration increases the output.
The fourth embodiment may be modified as follows.
That is, in the fourth embodiment, the brushless motor 11 may include a rotor core-connecting member for connecting the two rotor cores 221 and 231 to each other.
For example, the brushless motor 11 may include two holding plates 261 and rivets 262 made of non-magnetic material shown in
The holding plates 261 are disk members made of non-magnetic material. The holding plates 261 abut against axially outer end surfaces of the rotor cores 221 and 231. An outer diameter of the holding plate 261 is equal to those of the claw-shaped magnetic poles 224 and 234.
The number of rivets 262 is set to the same number (five in this example) of the core segments 222 and 232 which configure the first and second rotor cores 221 and 231. The rivets 262 are provided at equal intervals in the circumferential direction. Each of the rivets 262 extends in the axial direction through the basal portion 223 of the first rotor core 221, the field magnet 241, the basal portion 233 of the second rotor core 231, and the holding plates 261. Both ends of each of the rivets 262 in the axial direction (longitudinal direction) are swaged. Thus, the holding plates 261 are locked to the both ends of the rivet 262 in the axial direction. That is, the rivets 262 connect the holding plates 261 to each other, and the rivets 262 extend through the basal portions 223 and 233 of the core segments 222 and 232 and the field magnet 241. Thus, the rivets 262 are engaged with the basal portions 223 and 233 and the field magnet 241 in the circumferential direction and the radial direction.
In this case, it is possible to rigidly and integrally form the two rotor cores 221 and 231 and the field magnet 241 together, and to limit separation of the core segments 222 and 232 from each other in the radial direction. As a result, it is possible to enhance quality of the motor. According to the configuration including the holding plates 261 and the rivets 262, the basal portions 223 and 233 of the core segments 222 and 232 may include the connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b as in the above embodiment, or the connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b may be omitted. When the connecting convex portions and the connecting concave portions are omitted, the basal portions 223 and 233 which are adjacent in the circumferential direction are merely abutted against each other. Therefore, when the connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b are omitted, the shapes of the core segments 222 and 232 can be simplified.
In the fourth embodiment, the adjacent core segments 222 and 232 are connected to each other through the connecting portions (connecting convex portions 223a and 233a and connecting concave portions 223b and 233b) which are integrally formed on the basal portions 223 and 233. Instead, for example, the core segments 222 and 232 may be integrated by a discrete core segment-connecting member.
In an example shown in
The claw-shaped magnetic poles 224 and 234 (especially axially extending claws 224b and 234b) are formed by bending portions of the core segment raw materials 252 in the fourth embodiment. Instead, for example, the claw-shaped magnetic pole (pawl) may be configured by laminating a plurality of magnetic steel sheets (oriented magnetic steel sheets) in the axial direction.
As shown in
Next, a manufacturing procedure of the rotor cores 221 and 231 in the above-described configuration will be described with reference to
After the core segment raw materials 267 and the sheet members 265 are punched out, the basal portions 223 of the core segment raw materials 267 are annularly connected to one another. The sheet members 265 are laminated on the projections 224a of the core segment raw materials 267 in the axial direction (plate thickness direction of core segment raw material 267). By swaging and fixing the laminated projections 224a and the sheet members 265 to each other, the first rotor core 221 is completed. A manufacturing procedure of the second rotor core 231 is the same as that of the first rotor core 221.
The order of the procedure for annularly connecting the basal portions 223 to one another and the procedure for laminating the sheet members 265 on the projections 224a is not set, and any one of them may be carried out first. The sheet members 265 and the projection 224a may adhesively be fixed to each other instead of swaging.
In this case also, it is possible to reduce waste of the magnetic steel sheet 268 and to enhance yields. Further, it is possible to make the radial direction of the rotor 213 conform to the direction of magnetic characteristics of the claws 224c and 234c (sheet members 265) of the first and second claw-shaped magnetic poles 224 and 234. Hence, a magnetic flux easily flows in the radial direction in the claws 224c and 234c. As a result, it is possible to enhance output.
In the example shown in
Conversely, the circular connecting convex portions 223a and 233a and the circular connecting concave portions 223b and 233b of the above embodiments may be formed into the wedge shapes. The connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b are formed on and in the basal portion 223 one each, but they may be formed two each.
As shown in
In this case also, it is possible to reduce waste of the magnetic steel sheet 251 and to enhance yields.
In the fourth embodiment and the different examples shown in
In the fourth embodiment, the adjacent core segments 222 and 232 are connected to each other through the connecting convex portions 223a and 233a and the connecting concave portions 223b and 233b. Instead, they may be adhered and fixed each other.
In the fourth embodiment and the example shown in
The present disclosure is applied to an inner rotor type motor 11 in which the rotor 213 is arranged on an inner peripheral side of the stator 212 in the fourth embodiment. Instead, for example, the present disclosure may be embodied in an outer rotor type motor in which the rotor is arranged on an outer peripheral side of the stator.
The configuration of not only the rotor 213 but also of the motor 11 may be changed as necessary.
A fifth embodiment of the brushless motor will now be described with reference to
Therefore, only portions of the brushless motor that differ from the first embodiment will be described in detail, and description of the common portions will be omitted for the sake of convenience.
As shown in
Second rotor cores 32 have the same shapes as those of first rotor cores 31. A substantially cylindrical boss 32e is formed in a central portion of a second core base 32a. The rotation shaft 22 extends through the boss 32e. A plurality of second claw-shaped magnetic poles 32b are provided on an outer portion of the second core base 32a at equal intervals. Each of the second claw-shaped magnetic poles 32b projects radially outward, and extends along an axial direction toward a direction opposite from a projecting direction of the boss 32e.
Here, as shown in
In the fifth embodiment, the bosses 31e and 32e function as reinforcements.
In the rotor 21 of the fifth embodiment, the five first claw-shaped magnetic poles 31b which become north poles and the five second claw-shaped magnetic poles 32b which become south poles are alternately arranged in the circumferential direction, and the number of poles is ten (five pairs of poles). That is, in the fifth embodiment, the number of poles of the rotor 21 is set to “ten”, and the number of teeth 17a of a stator 16 is set to “twelve”. An inner diameter of an annular magnet 33 of the fifth embodiment is set greater than outer diameters of the bosses 31e and 32e.
As shown in
In a front end plate 14, a hall IC 43 as a magnetic sensor is provided at a position opposed to the sensor magnet 42 in the axial direction. If the hall IC 43 detects magnetic fields of the north pole and south pole based on the sensor magnet 42, the hall IC 43 outputs a High level detection signal and a Low level detection signal to a control circuit S.
Next, a manufacturing method of the rotor 21 configured as described above and its operation will be described.
The manufacturing method of the rotor 21 includes a burring process and a swaging process. In the burring process, the bosses 31e and 32e are formed in the first and second core bases 31a and 32a by burring. At this time, strong pressure is applied to portions of inner circumferential surfaces of the bosses 31e and 32e, and magnetic resistance at these portions becomes high. In the swaging process, the bosses 31e and 32e are swaged in a state where the rotation shaft 22 extend through the bosses 31e and 32e to fix the first rotor core 31 to the rotation shaft 22. At this time, strong pressure is applied to the outer circumferential surfaces of the bosses 31e and 32e, and magnetic resistance at these portions becomes high.
Next, advantages of the fifth embodiment in addition to advantage (1) of the first embodiment will be described below.
(24) The bosses 31e and 32e are formed by burring. The bosses 31e and 32e project in the axial direction toward a direction opposite from the projecting direction of the first and second claw-shaped magnetic poles 31b and 32b. If pressure is applied to metal by burring, magnetic resistance in the metal is increased by plastic deformation of the metal. Therefore, magnetic resistance of the bosses 31e and 32e becomes high. The bosses 31e and 32e project in the axial direction toward the direction opposite from the projecting direction of the first and second claw-shaped magnetic poles 31b and 32b. Hence, a contact portion between the first rotor core 31 and the rotation shaft 22 and a contact portion between the second rotor core 32 and the rotation shaft 22 separate from each other, and a magnetic path between the two contact portions becomes long. According to these facts, for example, it is possible to reduce a leakage magnetic flux in the axial direction generated between radially inner side portions of the first and second core bases 31a and 32a and by extension, to enhance motor efficiency. By the bosses 31e and 32e, it is possible to fix the first and second rotor cores 31 and 32 to the rotation shaft 22 over a wider axial range than plate thicknesses of the first and second core bases 31a and 32a. Hence, fixing strength between the rotation shaft 22 and the first and second rotor cores 31 and 32 can be increased.
(25) The first rotor core 31 is fixed to the rotation shaft 22 by swaging the bosses 31e and 32e in the state where the rotation shaft 22 extends through the bosses 31e and 32e. If pressure is applied to metal by swaging, magnetic resistance in the swaged metal is increased by plastic deformation of the metal. Therefore, magnetic resistance of the bosses 31e and 32e further becomes high. According to these facts, it is possible to further reduce the leakage magnetic flux in the axial direction generated between the radially inner side portions of the first and second core bases 31a and 32a and by extension, to further enhance the motor efficiency.
(26) The inner diameter of the annular magnet 33 is set to be greater than the outer diameters of the bosses 31e and 32e. Hence, it is possible to more effectively reduce the leakage magnetic flux in the axial direction.
The fifth embodiment may be modified as follows.
The bosses 31e and 32e are merely cylindrical in shape in the fifth embodiment. Instead, for example, inner circumferences of the bosses 31e and 32e may be formed to have non-circular shapes.
As shown in
As shown in
As shown in
Further, an inner circumference of a boss may be of a spline shape (not shown) as viewed from the axial direction for example. In this case, the rotation shaft has a shape corresponding to the inner circumference of the boss.
If these changes are employed, since the inner circumferences 71a to 73a of the bosses 71 to 73 are formed into non-circular shapes, it is possible to further enhance the fixing strength between the boss and the rotation shaft. Especially, the bosses 71 to 73 (by extension, also first and second rotor cores) and the rotation shaft are prevented from relatively rotating.
The bosses 31e and 32e are swaged in the state where the rotation shaft 22 extends through the bosses 31e and 32e and the rotor core 31 is fixed to the rotation shaft 22 in the fifth embodiment, but the invention is not limited to this configuration. For example, the rotor core 31 may be fixed to the rotation shaft by press fitting the rotation shaft into the bosses 31e and 32e.
Although the inner diameter of the annular magnet 33 is set greater than the outer diameters of the bosses 31e and 32e in the fifth embodiment, the invention is not limited to this configuration. For example, the inner diameter of the annular magnet 33 may be set to be equal to or smaller than the outer diameters of the bosses 31e and 32e.
In the fifth embodiment, the present disclosure is embodied in the brushless motor in which the number of poles of the rotor 21 is set to “ten” and the number of teeth 17a of a stator 16 is set to “twelve”, but the number of rotor 21 and the number of teeth 17a of the stator 16 may be changed. For example, the present disclosure may be embodied in a brushless motor in which the number of poles of the rotor 21 is set to “eight” and the number of teeth 17a of a stator 16 is set to “twelve”.
In the rotor 21 of the fifth embodiment, radially inner sides (back surfaces) of the first and second claw-shaped magnetic poles 31b and 32b may be provided with a back surface auxiliary magnet which is magnetized in the radial direction to suppress a leakage (short circuit) magnetic flux of these portions.
In the rotor 21 of the fifth embodiment, a circumferentially magnetized interpolar magnet may be provided between the first and second claw-shaped magnetic poles 31b and 32b in the circumferential direction to suppress a leakage magnetic flux of these portions.
The bosses 31e and 32e may be formed by sintering instead of burring, for example. The bosses formed by sintering are swaged and fixed to the rotation shaft as in the fifth embodiment. Thus, the same advantage as advantage (25) of the fifth embodiment can be obtained.
A sixth embodiment of the brushless motor will now be described with reference to
As shown in
A second rotor core 32 has the same shape as that of the first rotor core 31. A central bore 32f is formed in a central portion of a second core base 32a, and the rotation shaft 22 is inserted through the central bore 32f. A plurality of second claw-shaped magnetic poles 32b are provided on an outer portion of the second core base 32a at equal intervals. The second claw-shaped magnetic poles 32b project radially outward and extend in the axial direction. The first and second rotor cores 31 and 32 are fixed to the rotation shaft 22 by press fitting the rotation shaft 22 into the central bores 31f and 32f.
In the rotor 21 of the sixth embodiment, the five first claw-shaped magnetic poles 31b which become north poles and the five second claw-shaped magnetic poles 32b which become south poles are alternately arranged in the circumferential direction, and the number of poles is ten (five pairs of poles). That is, in the sixth embodiment, the number of poles of the rotor 21 is set to “ten”, and the number of teeth 17a of a stator 16 is set to “twelve”.
Here, as shown in
More specifically, the ribs 31g and 32g of the sixth embodiment extend from radially inner ends of the first and second core bases 31a and 32a to radially outer ends of the first and second claw-shaped magnetic poles 31b and 32b. The ribs 31g and 32g are (radially) arranged in the circumferential direction. The ribs 31g and 32g are provided at circumferentially central positions of the first and second claw-shaped magnetic poles 31b and 32b for the respective first and second claw-shaped magnetic poles 31b and 32b. A cross-section of each of the ribs 31g and 32g in the axial direction of the rotor 21 is quadrangle in shape. The ribs 31g and 32g having the above-described shapes are formed by pressing.
In the sixth embodiment, the ribs 31g and 32g function as reinforcements.
As shown in
In a front end plate 14, a hall IC 43 serving as a magnetic sensor is provided at a position opposed to the sensor magnet 42 in the axial direction. If the hall IC 43 detects magnetic fields of the north pole and south pole based on the sensor magnet 42, the hall IC 43 outputs a High level detection signal and a Low level detection signal to the control circuit S.
Next, operation of the brushless motor 11 having the above-described configuration will be described.
When three-phase drive current is supplied from the control circuit S to a winding 19, a rotating field is generated in the stator 16, and the rotor 21 is rotated and driven. At this time, the sensor magnet 42 which is opposed to the hall IC 43 rotates and the level of the detection signal which is output from the hall IC 43 is switched in accordance with a rotation angle (position) of the rotor 21. Based on the detection signal, three-phase drive current which is switched with optimal timing is supplied from the control circuit S to the winding 19. Thus, a rotating field is excellently generated, and the rotor 21 is rotated and driven continuously is a satisfactory manner.
Next, advantages of the sixth embodiment other than the advantage (1) of the first embodiment will be described below.
(27) The ribs 31g and 32g extending from the first and second core bases 31a and 32a to the first and second claw-shaped magnetic poles 31b and 32b are formed on the first and second rotor cores 31 and 32. Hence, even if an external force caused when the rotation shaft 22 is press-fitted into the central bores 31f and 32f of the central portions of the first and second core bases 31a and 32a or a centrifugal force caused at the time of high speed rotation is applied for example, it is possible to limit deformation (bending) of the first and second claw-shaped magnetic poles 31b and 32b from their base ends.
(28) The ribs 31g and 32g extend from the radial inner ends of the first and second core bases 31a and 32a. Hence, even if an external force caused when the rotation shaft 22 is press-fitted into the central bores 31f and 32f of the central portions of the first and second core bases 31a and 32a is applied, for example, it is possible to limit deformation of the radially inner side portions of the first and second core bases 31a and 32a.
(29) The ribs 31g and 32g extend to the radially outer ends of the first and second claw-shaped magnetic poles 31b and 32b. Hence, it is possible to limit deformation of the radially outer side portions of the first and second claw-shaped magnetic poles 31b and 32b.
(30) The ribs 31g and 32g are arranged in the circumferential direction of the rotor 21. The ribs 31g and 32g are provided at circumferentially central portions of the first and second claw-shaped magnetic poles 31b and 32b for the respective first and second claw-shaped magnetic poles 31b and 32b. Hence, it is possible to limit deformation of the first and second claw-shaped magnetic poles 31b and 32b in a balanced manner. Since the circumferentially central portions of the first and second claw-shaped magnetic poles 31b and 32b are thick, magnetic balance is also enhanced.
(31) The ribs 31g and 32g are formed through pressing. Hence, it is easy to produce the ribs 31g and 32g.
The sixth embodiment may be modified as follows.
The central bores 31f and 32f are merely formed in the central portions of the first and second core bases 31a and 32a in the sixth embodiment. Instead, for example, bosses into which the rotation shaft 22 is press-fitted may be formed in the central portions of the first and second core bases 31a and 32a such that the bosses project in the axial direction.
The first and second core bases 31a and 32a may be changed as shown in
In this case, the same advantages as the sixth embodiment may also be obtained. Since the boss 31e is formed, it is possible to fix the first and second rotor cores 31 and 32 and the rotation shaft 22 to each other over a wide axial range. Thus, it is possible to enhance fixing strength between the first and second rotor cores 31 and 32 and the rotation shaft 22. Further, the ribs 31g continuously extend from the boss 31e. Hence, strengths of the ribs 31g and the boss 31e are enhanced, and it is possible to further limit deformation at radially inner sides of the first and second core bases 31a and 32a.
Shapes of the ribs 31g and 32g of the sixth embodiment may be modified as long as they extend from the first and second core bases 31a and 32a to the first and second claw-shaped magnetic poles 31b and 32b.
The ribs may be changed as shown in
The ribs may be changed as shown in
The ribs may be changed as shown in
The ribs may be changed as shown in
Although the cross-sections of the ribs 31g and 32g extending in the axial direction of the rotor 21 are tetragonal in shape in the sixth embodiment, the invention is not limited to this configuration. For example, the cross-sections may be arcuate or triangular in shape.
The ribs 31g and 32g are formed by pressing in the sixth embodiment. Instead, ribs having the similar shape may be formed by sintering, for example.
The present disclosure is applied to the brushless motor in which the number of poles of the rotor 21 is set to “ten” and the number of teeth 17a of a stator 16 is set to “twelve” in the sixth embodiment. However, the number of the poles of the rotor 21 and the number of the teeth 17a of the stator 16 may be changed. For example, the present disclosure may be embodied in a brushless motor in which the number of poles of the rotor 21 is set to “eight” and the number of teeth 17a of a stator 16 is set to “twelve”.
In the rotor 21 of the sixth embodiment, radially inner sides (back surfaces) of the first and second claw-shaped magnetic poles 31b and 32b may be provided with radially magnetized back surface auxiliary magnets to reduce magnetic flux leakage (short circuit) at these portions.
In the rotor 21 of the sixth embodiment, a circumferentially magnetized interpolar magnet may be provided between the first and second claw-shaped magnetic poles 31b and 32b in the circumferential direction to reduce magnetic flux leakage at these portions.
A reference example shown in
The polygonal rib 87 can be displaced in the radial direction in each of the first and second core bases 31a and 32a. Thus, it is possible to effectively limit deformation of the first and second core bases 31a and 32a.
A reference example shown in
The inner ribs 88 may be displaced in the radial direction in the first and second core bases 31a and 32a. Thus, it is possible to effectively limit deformation of the first and second core bases 31a and 32a. Especially, the inner ribs 88 extend from radially inner ends of the first and second core bases 31a and 32a. Hence, even if an external force caused when the rotation shaft 22 is press-fitted into the central bores 31f and 32f of the central portions of the first and second core bases 31a and 32a is applied for example, it is possible to limit deformation at radially inner side portions of the first and second core bases 31a and 32a.
A seventh embodiment of the brushless motor will now be described with reference to
As shown in
In the seventh embodiment, a length of the fixing cylinder 115 in the axial direction, i.e., a length from a first end surface 115a as a first stepped surface to a second end surface 115b as a second stepped surface is the same as a length of the field magnet 140 in the axial direction (length from side surface 140a to side surface 140b).
As shown in
As shown in
As shown in
An outer diameter of the field magnet 140 matches with outer diameters of the first and second core bases 121 and 131, and a thickness (axial length) of the field magnet 140 is the same as an axial length of the fixing cylinder 115.
That is, as shown in
Next, the operation of the brushless motor 11 configured as described above will be described illustrating the assembling method of the rotor 104.
First, the rotation shaft 103 is press-fitted into the fixing cylinder 115, and the fixing cylinder 115 is crimped onto and fixed to the rotation shaft 103. The annular first end surface 115a of the fixing cylinder 115 is pressed in the axial direction using a cylindrical jig in a state where one of openings (opening closer to second end surface 115b for example) of the fixing cylinder 115 is abutted against the rotation shaft 103. The rotation shaft 103 is press-fitted from the other opening of the fixing cylinder 115 by pressing the first end surface 115a of the fixing cylinder 115 by the cylindrical jig.
Subsequently, the fixing cylinder 115 fixed to the rotation shaft 103 is inserted through the through bore 141 of the field magnet 140, and an outer circumferential surface of the fixing cylinder 115 and an inner circumferential surface of the through bore 141 of the field magnet 140 are fixed to each other. At this time, the field magnet 140 is fixed to the fixing cylinder 115 such that the axial first end surface 115a and the axial second end surface 115b of the fixing cylinder 115 are flush with side surfaces 140a and 140b of the field magnet 140.
The field magnet 140 is positioned with respect to the fixing cylinder 115 by inserting, through the through bore 141, the fixing cylinder 115 which the rotation shaft 103 is press-fitted into and fixed to.
Next, the rotation shaft 103 is press-fitted into the through bore 120a of the first rotor core 120 (first core base 121) by the above-described method such that the opposing surface 121a of the first core base 121 and the side surface 140a of the field magnet 140 are opposed to each other. At this time, the rotation shaft 103 is press-fitted into the through bore 120a until the opposing surface 121a of the first core base 121 abuts against the axial first end surface 115a (side surface 140a of the field magnet 140) of the fixing cylinder 115.
Then, a peripheral portion of the through bore 120a in the opposing surface 121a of the first rotor core 120 abuts against the first end surface 115a of the fixing cylinder 115. Further press fitting motion of the first rotor core 120 in the axial direction (toward field magnet 140) is regulated. Therefore, a case where a load is applied to the field magnet 140 by press fitting the rotation shaft 103 into the first rotor core 120 is avoided. As a result, when the rotation shaft 103 is press-fitted into the first rotor core 120, a load is not applied from the first rotor core 120 directly to the field magnet 140. Therefore, damage such as crack is not generated in the field magnet 140.
The opposing surface 121a of the first core base 121 and the side surface 140a of the field magnet 140 may be adhered and fixed to each other through magnetic adhesive.
Next, the rotation shaft 103 is press-fitted into the through bore 130a of the second rotor core 130 (second core base 131) in a state where the opposing surface 131a of the second core base 131 and the side surface 140b of the field magnet 140 are opposed to each other. At this time, this press-fitting operation is carried out while adjusting a relative circumferential position of the second core base 131 with respect to the previously fixed first rotor core 120.
The rotation shaft 103 is press-fitted into the through bore 120a until the opposing surface 131a of the second core base 131 abuts against the axial second end surface 115b (side surface 140a of field magnet 140) of the fixing cylinder 115.
Then, a peripheral portion of the through bore 130a in the opposing surface 131a of the second rotor core 130 abuts against the second end surface 115b of the fixing cylinder 115. Further press fitting motion of the second rotor core 130 in the axial direction (toward field magnet 140) is regulated. Therefore, a case where a load is applied to the field magnet 140 by press fitting the rotation shaft 103 into the second rotor core 130 is avoided. As a result, when the rotation shaft 103 is press-fitted into the second rotor core 130, a load is not applied from the second rotor core 130 directly to the field magnet 140. Therefore, damage such as crack is not generated in the field magnet 140.
In the seventh embodiment, the fixing cylinder 115 functions as a reinforcement.
The opposing surface 131a of the second core base 131 and the side surface 140b of the field magnet 140 may be adhered and fixed to each other using magnetic adhesive.
Thus, the rotation shaft 103 is press-fitted into and fixed to the first and second rotor cores 120 and 130. The fixing cylinder 115 and the field magnet 140 are arranged between the press-fitted and fixed first and second rotor cores 120 and 130. Therefore, the field magnet 140 is fixed to the fixing cylinder 115.
Next, the first back surface auxiliary magnets 151 are arranged on and fixed to the back surfaces f1b of the first magnetic pole portions 124, and the second back surface auxiliary magnets 152 are arranged on and fixed to the back surfaces f2b of the second magnetic pole portions 134.
More specifically, the first back surface auxiliary magnet 151 is arranged in a space formed by the back surface f1b of each of the first magnetic pole portions 124, i.e., the outer circumferential surface 131c of the second core base 131, the outer circumferential surface 140c of the field magnet 140, and a surface 123a of the first base 123 closer to the second rotor core, and the first back surface auxiliary magnet 151 is adhered and fixed using magnetic adhesive.
In the same manner, the second back surface auxiliary magnet 152 is arranged and fixed to a space formed by the back surface f2b of the second magnetic pole portion 134, i.e., the outer circumferential surface 121c of the first core base 121, the outer circumferential surface 140c of the field magnet 140, and a surface 133a of the second basal portion 133 closer to the first rotor core.
Finally, the first and second interpolar magnets 153 and 154 are arranged and fixed.
More specifically, the first interpolar magnet 153 is arranged between a flat surface formed by a circumferential end surface 122a of the first claw-shaped magnetic pole 122 and a circumferential end surface of the first back surface auxiliary magnet 151 and a flat surface formed by a circumferential end surface 132b of the second claw-shaped magnetic pole 132 and a circumferential end surface of the second back surface auxiliary magnet 152. The first interpolar magnet 153 is adhered and fixed using magnetic adhesive.
Similarly, the second interpolar magnet 154 is arranged between a flat surface formed by a circumferential end surface 122b of the first claw-shaped magnetic pole 122 and a circumferential end surface of the first back surface auxiliary magnet 151 and a flat surface formed by a circumferential end surface 132a of the second claw-shaped magnetic pole 132 and a circumferential end surface of the second back surface auxiliary magnet 152. The second interpolar magnet 154 is fixed.
This complete the assembling of the rotor 104.
Next, advantages of the seventh embodiment in addition to advantage (1) of the first embodiment will be described.
(32) In the seventh embodiment, the rotor 104 can be produced only by fixing the field magnet 140 to the fixing cylinder 115 which is crimped onto and fixed to the rotation shaft 103, and by press fitting and fixing the rotation shaft 103 into the first and second rotor cores 120 and 130. Hence, the assembling operation of the rotor 104 becomes extremely easy.
Further, it is possible to obtain a strong connecting structure by press fitting, crimping and fixing the rotation shaft 103 into and onto the first and second rotor cores 120 and 130. Thus, it is possible to prevent vibration and noise of the rotor 104 caused by rotation.
(33) In the seventh embodiment, when the rotation shaft 103 is press-fitted into the first rotor core 120, the peripheral portion of the through bore 120a in the opposing surface 121a of the first rotor core 120 abuts against the first end surface 115a of the fixing cylinder 115. Thus, further press fitting motion of the first rotor core 120 in the axial direction (toward the field magnet 140) is regulated. Therefore, when the rotation shaft 103 is press-fitted into the first rotor core 120, a load from the first rotor core 120 is not applied directly to the field magnet 140. Hence, there is no fear that damage such as crack is generated in the field magnet 140 during the assembling operation.
(34) In the seventh embodiment, when the rotation shaft 103 is press-fitted into the second rotor core 130, the peripheral portion of the through bore 130a in the opposing surface 131a of the second rotor core 130 abuts against the second end surface 115b of the fixing cylinder 115. Thus, further press fitting motion of the second rotor core 130 in the axial direction (toward the field magnet 140) is regulated. Therefore, when the rotation shaft 103 is press-fitted into the second rotor core 130, a load from the second rotor core 130 is not applied directly to the field magnet 140. Hence, there is no fear that damage such as crack is generated in the field magnet 140 during the assembling operation.
(35) In the seventh embodiment, the fixing cylinder 115 is made of non-magnetic material like the rotation shaft 103, and the fixing cylinder 115 and the field magnet 140 are fixed to each other. Therefore, it is possible to avoid a case where a magnetic flux of the field magnet 140 becomes a leakage magnetic flux and the leakage magnetic flux flows through the rotation shaft 103 and the fixing cylinder 115 which are made of non-magnetic material.
(36) According to the seventh embodiment, the axial length of the fixing cylinder 115 is the same as the axial length of the field magnet 140 which is arranged between the first rotor core 120 and the second rotor core 130. Therefore, at the time of press-fitting and crimpling operation of the first and second rotor cores 120 and 130, the opposing surfaces 121a and 131a of the first and second rotor cores 120 and 130 can easily be brought into close contact with each other without applying a load to the field magnet 140. As a result, magnetic resistance between the first and second rotor cores 120 and 130 and the field magnet 140 can be made small.
The seventh embodiment may be modified as follows.
The fixing cylinder 115 made of non-magnetic material is made of stainless steel like the rotation shaft 103 in the seventh embodiment and any non-magnetic material can be used. For example, the fixing cylinder 115 may be made of aluminum or resin.
In the seventh embodiment, the axial length of the fixing cylinder 115 is the same as the thickness (axial length) of the field magnet 140. Instead of this configuration, the axial length of the fixing cylinder 115 may be greater than the thickness of the field magnet 140.
In this case, a gap is formed between the field magnet 140 and the first and second rotor cores 120 and 130, and magnetic resistance is increased. Hence, it is necessary that the axial length of the fixing cylinder 115 is increased within a range in which reduction of density of magnetic flux does not affect rotation.
In the seventh embodiment, the rotation shaft 103 is press-fitted into and cramped onto the fixing cylinder 115, thereby forming a large-diameter portion of the rotation shaft 103. As shown in
A large-diameter portion having the same shape as that of the fixing cylinder 115 may integrally be formed on the rotation shaft 103 by insert molding or double molding.
The field magnet 140 is made of neodymium magnet in the seventh embodiment. Instead, the field magnet 140 may be made of ferrite sintered magnet, samarium-cobalt magnet or the like.
Although the rotor 104 is provided with the first and second back surface auxiliary magnets 151 and 152 in the seventh embodiment, they may be omitted.
Although the rotor 104 is provided with the first and second interpolar magnet 153 and 154 in the seventh embodiment, they may be omitted. The first and second back surface auxiliary magnets 151 and 152 may also be omitted.
Number | Date | Country | Kind |
---|---|---|---|
2012-249191 | Nov 2012 | JP | national |
2012-249192 | Nov 2012 | JP | national |
2013-010104 | Jan 2013 | JP | national |
2013-011217 | Jan 2013 | JP | national |
2013-024711 | Feb 2013 | JP | national |
2013-041916 | Mar 2013 | JP | national |
2013-064339 | Mar 2013 | JP | national |
2013-157994 | Jul 2013 | JP | national |
Number | Name | Date | Kind |
---|---|---|---|
2651733 | Stark | Sep 1953 | A |
3553510 | Howey | Jan 1971 | A |
4388545 | Honsinger et al. | Jun 1983 | A |
4882515 | Radomski | Nov 1989 | A |
5148070 | Frye | Sep 1992 | A |
5955807 | Kajiura et al. | Sep 1999 | A |
6013967 | Ragaly et al. | Jan 2000 | A |
6157111 | Asao | Dec 2000 | A |
6337529 | Higashino et al. | Jan 2002 | B1 |
6396177 | Shin et al. | May 2002 | B1 |
20010002095 | Sakamoto | May 2001 | A1 |
20050206254 | Tsuge et al. | Sep 2005 | A1 |
20060055270 | Peterson | Mar 2006 | A1 |
20070170809 | Itoh | Jul 2007 | A1 |
20080053407 | Maier et al. | Mar 2008 | A1 |
20090184599 | Kanazawa | Jul 2009 | A1 |
20090230803 | Nakayama et al. | Sep 2009 | A1 |
20100084215 | Sakatani et al. | Apr 2010 | A1 |
20110001383 | Shimomura et al. | Jan 2011 | A1 |
20120112585 | Kajiura | May 2012 | A1 |
20120187794 | Inoue et al. | Jul 2012 | A1 |
20130057102 | Yamada et al. | Mar 2013 | A1 |
20130106208 | Yamada et al. | May 2013 | A1 |
Number | Date | Country |
---|---|---|
2354289 | Dec 1999 | CN |
2372831 | Apr 2000 | CN |
101946390 | Jan 2011 | CN |
2006059 | May 1979 | GB |
S40-2927 | Jan 1965 | JP |
S54-26615 | Jul 1977 | JP |
S53-135512 | Oct 1978 | JP |
S59-34482 | Mar 1984 | JP |
H 1-101166 | Jul 1989 | JP |
H03-117357 | Dec 1991 | JP |
H04-325863 | Nov 1992 | JP |
H3-39355 | Apr 1993 | JP |
5-43749 | Jun 1993 | JP |
H05-168278 | Jul 1993 | JP |
H06-022481 | Jan 1994 | JP |
H06-070526 | Mar 1994 | JP |
H06-133478 | May 1994 | JP |
H06-245461 | Sep 1994 | JP |
H11-150902 | Jun 1999 | JP |
H11206052 | Jul 1999 | JP |
H11-275831 | Oct 1999 | JP |
2000-209800 | Jul 2000 | JP |
2001-218403 | Aug 2001 | JP |
2001-314071 | Nov 2001 | JP |
2002-051525 | Feb 2002 | JP |
2002-136091 | May 2002 | JP |
2002-209370 | Jul 2002 | JP |
2002-247817 | Aug 2002 | JP |
2003-204660 | Jul 2003 | JP |
2008045556 | Feb 2008 | JP |
2008-109773 | May 2008 | JP |
2008-312402 | Dec 2008 | JP |
2009-219309 | Sep 2009 | JP |
2009-261056 | Nov 2009 | JP |
2009-261154 | Nov 2009 | JP |
4468033 | Mar 2010 | JP |
2010-136588 | Jun 2010 | JP |
2010-199622 | Sep 2010 | JP |
WO 2012067223 | May 2012 | JP |
2012-115085 | Jun 2012 | JP |
2013-005627 | Jan 2013 | JP |
2013-064339 | Aug 2016 | JP |
2011040247 | Jul 2011 | WO |
Entry |
---|
Yamada Yoji; Morita Chie; Fuji Yuuki; Kato Shigemasa, Rotor and Motor, 2012-05-24, ASMO Co Ltd, WO 2012067223. |
Japanese Office Action of JP 2012-249191 dated Mar. 7, 2016 with its English Translation. |
Japanese Office Action of JP Application No. 2013-011217 dated May 24, 2016 along with its English Translation. |
U.S. Office Action of U.S. Appl. No. 14/075,942 dated May 17, 2016. |
Japanese Office Action of JP Application No. 2013-011388 dated May 10, 2016 along with its English Translation. |
Japanese Office Action of JP Application No. 2013-024712 dated May 10, 2016 along with its English Translation. |
Japanese Office Action of JP Application No. 2013-064340 dated Jun. 28, 2016 along with its English Translation. |
Japanese Office Action of JP 2013-024711, dated Jul. 12, 2016. |
Japanese Office Action of JP 2013-157994, dated Jul. 12, 2016 along with its English Translation. |
Japanese Office Action of JP 2013-064339 dated Aug. 2, 2016 along with its English Translation. |
Number | Date | Country | |
---|---|---|---|
20140139065 A1 | May 2014 | US |