WO2021260809A1

WO2021260809A1 - Stepping motor

Info

Publication number: WO2021260809A1
Application number: PCT/JP2020/024660
Authority: WO
Inventors: 祥子川崎; 徹小川
Original assignee: 三菱電機株式会社
Priority date: 2020-06-23
Filing date: 2020-06-23
Publication date: 2021-12-30

Abstract

A stepping motor (1) is provided with a claw pole stator core (3), and the stator core (3) uses a punched core (31). The punched core (31) comprises: a belt-like portion (41) corresponding to the back yoke portion (24) of the stator core (3) in an expanded state; a plurality of trapezoidal portions (44) corresponding to an upper end magnetic path portion (22) or a lower end magnetic path portion (23) of the stator core (3); a gap portion (45) provided between mutually adjacent trapezoidal portions (44) of the plurality of trapezoidal portions (44); and a plurality of claw-like portions (46) corresponding to magnetic pole portions (21) of the stator core (3).

Description

Stepping motor

This disclosure relates to a stepping motor.

Conventionally, a stepping motor having a claw pole type stator core has been developed. More specifically, a stepping motor having a stator core (hereinafter sometimes referred to as "punched core") manufactured by punching a steel plate has been developed. Patent Document 1 discloses a motor having such a stator core.

Japanese Unexamined Patent Publication No. 2016-141881

The shape of the stator core in the motor described in Patent Document 1 is a hollow annular shape. The cross-sectional shape of the hollow annulus is rectangular. The inner peripheral portion of the annulus (hereinafter referred to as "magnetic pole portion") is composed of a plurality of claw-shaped portions (hereinafter referred to as "claw-shaped portions"). A plurality of magnetic poles are formed by the plurality of claw-shaped portions. Further, the outer peripheral portion of the annulus (hereinafter referred to as "back yoke portion"), the top surface portion of the annulus (hereinafter referred to as "upper end magnetic path portion"), and the bottom surface portion of the annulus (hereinafter referred to as "lower end magnetic path portion"). ”) And the magnetic poles form a rectangular annular magnetic path. That is, a magnetic path along the chaining direction with respect to the annulus is formed.

Here, when the stator core in the motor described in Patent Document 1 is manufactured, the back yoke portion, the upper end magnetic path portion, and the lower end magnetic path portion are formed by bending a strip-shaped portion (hereinafter referred to as “belt-shaped portion”) in the punched steel plate. Is formed (see, for example, FIGS. 1 to 5 of Patent Document 1). At this time, from the viewpoint of forming the upper end magnetic path portion and the lower end magnetic path portion, the strip-shaped portion is bent so as to compress in the circumferential direction. There is a problem that magnetic deterioration occurs due to such compression.

The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to suppress the occurrence of magnetic deterioration due to compression of a steel plate in a stepping motor having a claw pole type stator core.

The stepping motor according to the present disclosure is a stepping motor including a claw pole type stator core, in which the stator core uses a punched core, and the punched core has a strip shape corresponding to the back yoke portion of the stator core in the deployed state. A gap portion provided between a portion, a plurality of trapezoidal portions corresponding to the upper end magnetic path portion or the lower end magnetic path portion of the stator core, and adjacent trapezoidal portions among the plurality of trapezoidal portions, and a magnetic pole of the stator core. It is provided with a plurality of claw-shaped portions corresponding to the portions.

According to the present disclosure, since it is configured as described above, it is possible to suppress the occurrence of magnetic deterioration due to the compression of the steel sheet.

It is sectional drawing which shows the main part of the stepping motor which concerns on Embodiment 1. FIG. It is explanatory drawing which shows the phase difference between the stators in the stepping motor which concerns on Embodiment 1. FIG. It is another explanatory diagram which shows the phase difference between the stators in the stepping motor which concerns on Embodiment 1. FIG. It is sectional drawing which shows the main part of each stator in the stepping motor which concerns on Embodiment 1, and is sectional drawing which shows the state before assembly. It is sectional drawing which shows the main part of each stator in the stepping motor which concerns on Embodiment 1, and is sectional drawing which shows the state after assembly. It is a top view which shows the individual punching core in each stator in the stepping motor which concerns on Embodiment 1, and is the top view which shows the expanded state. It is a top view which shows the individual punching core in each stator in the stepping motor which concerns on Embodiment 1, and is explanatory drawing which shows the state which each 1st bending part and 2nd bending part were bent. It is a top view which shows the individual punching core in each stator in the stepping motor which concerns on Embodiment 1, and is the top view which shows the state in the process of bending a strip-shaped part. It is a top view which shows the individual punching core in each stator in the stepping motor which concerns on Embodiment 1, and is the top view which shows the completed state. It is sectional drawing which shows the individual punching core in each stator in the stepping motor which concerns on Embodiment 1, and is sectional drawing which shows the completed state. It is sectional drawing which shows the main part of the stator for comparison, and is the sectional drawing which shows the state before assembly. It is sectional drawing which shows the main part of the stator for comparison, and is the sectional drawing which shows the state after assembling. It is a top view which shows the individual punching cores in the stator for comparison, and is the top view which shows the developed state. It is sectional drawing which shows the individual punching core in the stator for comparison, and is the sectional drawing which shows the completed state. It is explanatory drawing which shows the example of the magnetic path in each stator in the stepping motor which concerns on Embodiment 1. FIG. It is a top view which shows the part of each punching core in each stator in the stepping motor which concerns on Embodiment 1, and is the top view which shows the example of the case where each claw-shaped part is inclined. It is a top view which shows the part of each punching core in each stator in the stepping motor which concerns on Embodiment 1, and is the top view which shows the example of the case where the notch-like recess is provided.

Hereinafter, in order to explain this disclosure in more detail, the mode for carrying out this disclosure will be described according to the attached drawings.

Embodiment 1.
FIG. 1 is a cross-sectional view showing a main part of the stepping motor according to the first embodiment. FIG. 2 is an explanatory diagram showing a phase difference between stators in the stepping motor according to the first embodiment. The stepping motor according to the first embodiment will be described with reference to FIGS. 1 and 2.

As shown in FIG. 1, the stepping motor 1 has a plurality of stators 2. More specifically, the stepping motor 1 has two stators 2_1 and 2_2. Hereinafter, the direction along the axis A of the stepping motor 1 is referred to as "axial direction". The two stators 2_1 and 2_2 are arranged so as to overlap each other in the axial direction.

Hereinafter, the direction of rotation with respect to the axis A is simply referred to as "direction of rotation". As shown in FIG. 2, the two stators 2_1 and 2_2 have a phase difference θ with respect to the rotation direction. The phase difference θ is set to a value obtained by dividing one round of the machine angle (that is, 360 ° or 2π) by N × 2 and further dividing by 2. Here, N is a half value with respect to the number of magnetic poles in each stator 2. In other words, each stator 2 has N × 2 magnetic poles. For example, when the number of magnetic poles is 24 (N × 2 = 24), the phase difference θ is set to 7.5 ° (360 ° / 24/2 = 7.5 °). Since the phase difference θ is provided, torque for rotating the rotor 5, which will be described later, is generated.

Each stator 2 has a stator core 3. More specifically, the stator 2_1 has a stator core 3_1 and the stator 2_2 has a stator core 3_1. The shape of each stator core 3 is a hollow annular shape. The cross-sectional shape of each stator core 3 is rectangular.

A coil 4 is provided in the hollow portion of each stator core 3. That is, the coil 4_1 is provided in the hollow portion of the stator core 3_1, and the coil 4_1 is provided in the hollow portion of the stator core 3_1. In this way, the main parts of the individual stators 2 are configured.

One rotor 5 is passed through the two stators 2_1 and 2_2. The rotor 5 has a cylindrical rotor magnet 6. The rotor magnet 6 is magnetized so that the number of magnetic poles in the rotation direction is N × 2. That is, the number of magnetic poles (N × 2) in the rotor 5 is the same as the number of magnetic poles (N × 2) in each stator 2.

The rotor magnet 6 is held by a holding portion (hereinafter referred to as "magnet holding portion") 7 for the rotor magnet 6. An output shaft 8 is provided at one end of the magnet holding portion 7. In this way, the main part of the rotor 5 is configured.

The housing 9 and the bracket 10 constitute the housing portion 11 of the stepping motor 1. A sealing material 12 is provided between the housing 9 and the bracket 10. The stators 2_1 and 2_2 and the rotor 5 are housed in the housing 11. However, the tip portion of the output shaft 8 projects to the outside of the housing portion 11.

Inside the housing portion 11, a bearing 13_1 is provided between the rotor 5 and the housing 9, and a bearing 13_1 is provided between the rotor 5 and the bracket 10. The rotor 5 is rotatably supported with respect to the stators 2_1 and 2_2 by bearings 13_1 and 13_2.

Further, the stepping motor 1 has a connector portion 14. A current is supplied to the coils 4_1 and 4_2 by the connector portion 14. As a result, the stepping motor 1 operates.

In this way, the main part of the stepping motor 1 is configured.

The stepping motor 1 is used for, for example, an actuator. The actuator is used for various purposes. Specifically, for example, the actuator is used to control the opening degree of an EGR (Exhaust Gas Recirculation) valve. In this case, the output shaft 8 of the rotor 5 is mechanically connected to the valve body of the EGR valve via the output unit (hereinafter, simply referred to as “output unit”) of the actuator. The rotation of the rotor 5 changes the opening degree of the EGR valve. Further, by maintaining the position of the rotor 5 with respect to the rotation direction, the opening degree of the EGR valve is maintained.

Here, the actuator may be a linear motion type or a rotary type. That is, the actuator may have a mechanism for converting the rotation of the rotor 5 into a linear motion of the output unit, or may not have the mechanism.

Further, when the actuator is a rotary type, the output unit may rotate in the same direction as the rotation direction of the rotor 5, or rotates in the direction opposite to the rotation direction of the rotor 5. It may be a thing. That is, the actuator may have a mechanism for converting the rotation direction, or may not have the mechanism. The mechanism is, for example, a combination of a plurality of gears.

Next, the individual stators 2 will be described with reference to FIGS. 3 and 4. More specifically, the stator core 3 in each stator 2 will be described.

As shown in FIGS. 3 and 4, each stator core 3 is a claw pole type. Each stator core 3 includes a magnetic pole portion 21, an upper end magnetic path portion 22, a lower end magnetic path portion 23, and a back yoke portion 24. Each stator core 3 is a combination of two punched cores 31_1 and 31_2.

The magnetic pole portion 21 is formed by two punched cores 31_1 and 31_2. More specifically, in the inner peripheral portion of each stator core 3, the N claw-shaped portions in one punched core 31_1 and the N claw-shaped portions in the other punched core 31_1 are arranged so as to occlude with each other. ing. In this way, the magnetic pole portion 21 is formed. That is, N × 2 magnetic poles are formed by the N × 2 claw-shaped portions. In the figure, L indicates the length of each nail-shaped portion.

The upper end magnetic path portion 22 is formed by one of the two punched cores 31_1 and 31_2, the punched core 31_1. The lower end magnetic path portion 23 is formed by the other punched core 31_2 of the two punched cores 31_1 and 31_2. The back yoke portion 24 is formed by two punched cores 31_1 and 31_2.

That is, each stator core 3 has a structure divided into upper and lower parts. As described above, the cross-sectional shape of each stator core 3 is a rectangular annular shape. On the other hand, the cross-sectional shape of each punched core 31 is U-shaped (that is, U-shaped).

As shown in FIG. 4, a rectangular annular magnetic path P1 is formed in each stator core 3. The magnetic path P1 sequentially passes through the magnetic pole portion 21, the upper end magnetic path portion 22, the back yoke portion 24, the lower end magnetic path portion 23, and the magnetic pole portion 21.

Next, a method for manufacturing each punched core 31 will be described with reference to FIGS. 5 to 9.

First, by punching the steel plate, individual punched cores 31 in the unfolded state (hereinafter referred to as "expanded state") are formed. FIG. 5 shows the individual punched cores 31 in the deployed state. That is, FIG. 5 shows individual punched cores 31 at the timing of punching from the steel plate.

As shown in FIG. 5, each punched core 31 in the deployed state includes a band-shaped portion 41. A concave portion 42 for connection is provided at one end of the band-shaped portion 41 (hereinafter referred to as “first end portion”). A convex portion 43 for connection is provided at the other end of the band-shaped portion 41 (hereinafter referred to as “second end portion”). In the figure, W indicates the width of the band-shaped portion 41.

N trapezoidal portions (hereinafter referred to as "trapezoidal portions") 44 are provided on one side portion of the strip-shaped portion 41 (hereinafter referred to as "first side portion"). More specifically, the lower bottom portion of each trapezoidal portion 44 is continuous with the first side portion of the strip-shaped portion 41. For each of the two trapezoidal portions 44 adjacent to each other among the N trapezoidal portions 44, a gap portion 45 is provided between the two trapezoidal portions 44. That is, each punched core 31 is provided with N-1 gaps 45. The shape of each gap 45 is wedge-shaped (that is, V-shaped).

A claw-shaped portion 46 is provided on the upper bottom portion of each trapezoidal portion 44. That is, in each punching core 31, N claw-shaped portions 46 corresponding to N trapezoidal portions 44 are provided. The individual claw-shaped portions 46 are provided so as to project from the upper bottom portion of the corresponding trapezoidal portion 44. The root of each claw-shaped portion 46 is continuous with the upper bottom portion of the corresponding trapezoidal portion 44.

Next, a portion (hereinafter referred to as "first bent portion") 47 between the root portion of each claw-shaped portion 46 and the upper bottom portion of the corresponding trapezoidal portion 44 is bent. Next, a portion (hereinafter referred to as "second bent portion") 48 between the lower bottom portion of each trapezoidal portion 44 and the first side portion of the strip-shaped portion 41 is bent. In FIG. 5, each first bent portion 47 is indicated by a broken line, and the second bent portion 48 is indicated by a broken line.

At this time, the direction in which each first bent portion 47 is bent is the same as the direction in which the second bent portion 48 is bent. Further, the angle at which each first bent portion 47 is bent is 90 ° or approximately 90 °. The angle at which the second bent portion 48 is bent is 90 ° or approximately 90 °.

That is, each of the first bent portion 47 and the second bent portion 48 is bent by a so-called "mountain fold". Alternatively, each of the first bent portion 47 and the second bent portion 48 is bent by a so-called "valley fold". FIG. 6 shows a state in which each of the first bent portion 47 and the second bent portion 48 is bent.

Next, the strip 41 is bent into a cylindrical shape. FIG. 7 shows a state in which the band-shaped portion 41 is being bent into a cylindrical shape.

At this time, the strip-shaped portion 41 is bent into a cylindrical shape while the second bent portion 48 is bent, so that the individual gap portions 45 are filled. In other words, for each of the two trapezoidal portions 44 adjacent to each other, one leg of one of the two trapezoidal portions 44 is the other trapezoidal portion of the two trapezoidal portions 44. It is in a state of being in contact with one leg of 44. In the figure, I indicates an interface between the two trapezoidal portions 44. Further, the first end portion of the strip-shaped portion 41 is in a state of facing the second end portion of the strip-shaped portion 41.

Next, the convex portion 43 engages with the concave portion 42. As a result, the first end portion of the strip-shaped portion 41 is connected to the second end portion of the strip-shaped portion 41. By such engagement, the fixing between the first end portion of the strip-shaped portion 41 and the second end portion of the strip-shaped portion 41 can be strengthened.

In this way, each punched core 31 is completed. Hereinafter, the state in which each punched core 31 is completed is referred to as a “completed state”. 8 and 9 show the individual punched cores 31 in the finished state.

That is, the strip-shaped portion 41 in the deployed state corresponds to the back yoke portion 24 in the corresponding stator core 3. Further, the N trapezoidal portions 44 in the deployed state correspond to the upper end magnetic path portion 22 or the lower end magnetic path portion 23 in the corresponding stator core 3. Further, the N claw-shaped portions 46 in the deployed state correspond to the magnetic pole portions 21 in the corresponding stator core 3.

Next, the manufacturing method of each stator 2 will be described.

First, the punched core 31_1 is manufactured by the above manufacturing method. Further, the punched core 31_2 is manufactured by the above manufacturing method.

Next, the corresponding coil 4 is inserted into the concave portion of the punching core 31_1 having a U-shaped cross section (that is, a U-shaped cross section). Alternatively, the corresponding coil 4 is inserted into a concave portion having a U-shaped cross section (that is, a U-shaped cross section) in the punching core 31_2.

Next, the punching core 31_1 is arranged to face the punching core 31_1. At this time, the positions of the punched cores 31_1 and 31_2 with respect to the rotation direction are set to positions where the N claw-shaped portions 46 in the punched core 31_1 and the N claw-shaped portions 46 in the punched core 31_2 mesh with each other.

Next, the punching core 31_1 is attached to the punching core 31_1. As a result, the N claw-shaped portions 46 in the punched core 31_1 and the N claw-shaped portions 46 in the punched core 31_1 are arranged so as to occlude with each other.

In this way, each stator 2 is manufactured. That is, each of the two stators 2_1 and 2_2 is manufactured. The two manufactured stators 2_1 and 2_2 are arranged so as to overlap each other with a phase difference θ. By passing the rotor 5 through the manufactured stator 2, the main part of the stepping motor 1 is manufactured.

Here, in the upper end magnetic path portion 22 of each stator core 3, there are N interfaces I_1. This is for each of the two adjacent trapezoidal portions 44 of the N trapezoidal portions 44 in the punched core 31_1, one leg of the trapezoidal portion 44 of the two trapezoidal portions 44 and the two. It corresponds to a portion of the trapezoidal portions 44 in which one leg of the other trapezoidal portion 44 is in contact with each other (see FIG. 8).

Similarly, in the lower end magnetic path portion 23 of each stator core 3, there are N interfaces I_2. This is for each of the two adjacent trapezoidal portions 44 of the N trapezoidal portions 44 in the punched core 31_2, one leg of the trapezoidal portion 44 of the two trapezoidal portions 44 and the two. It corresponds to a portion of the trapezoidal portions 44 in which one leg of the other trapezoidal portion 44 is in contact with each other (see FIG. 8).

Next, with reference to FIGS. 10 and 11, a comparative stator 2'for each stator 2 will be described.

As shown in FIGS. 10 and 11, the stator 2'has a stator core 3'. The shape of the stator core 3'is a hollow annular shape. The cross-sectional shape of the stator core 3'is rectangular. A coil 4'is provided in the hollow portion of the stator core 3'. In this way, the main part of the stator 2'is configured.

As shown in FIGS. 10 and 11, the stator core 3'is a claw pole type. The stator core 3'includes a magnetic pole portion 21', an upper end magnetic path portion 22', a lower end magnetic path portion 23', and a back yoke portion 24'. The stator core 3'is a combination of two punched cores 31'_1, 31'_2.

The magnetic pole portion 21'is formed by two punched cores 31'_1, 31'_ 2. More specifically, in the inner peripheral portion of the stator core 3', the N claw-shaped portions in one punched core 31'_1 and the N claw-shaped portions in the other punched core 31'_2 mesh with each other. Is located in. In this way, the magnetic pole portion 21'is formed. That is, N × 2 magnetic poles are formed by the N × 2 claw-shaped portions. In the figure, L'indicates the length of each nail-shaped portion.

The upper end magnetic path portion 22'is formed by one of the two punched cores 31'_1, 31'_2, the punched core 31'_1. The lower end magnetic path portion 23'is formed by the other punched core 31'_2 of the two punched cores 31'_1, 31'_2. The back yoke portion 24'is formed by two punched cores 31'_1, 31'_2.

That is, the stator core 3'has a structure divided into upper and lower parts. As described above, the cross-sectional shape of each stator core 3'is a rectangular annular shape. On the other hand, the cross-sectional shape of each punched core 31'is U-shaped (that is, U-shaped).

As shown in FIG. 11, a rectangular annular magnetic path P1'is formed in the stator core 3'. The magnetic path P1'passes through the magnetic pole portion 21', the upper end magnetic path portion 22', the back yoke portion 24', the lower end magnetic path portion 23', and the magnetic pole portion 21'in order.

Next, a method of manufacturing each punched core 31'will be described with reference to FIGS. 12 and 13.

First, by punching the steel plate, each punched core 31'in the unfolded state is manufactured. FIG. 12 shows the individual punched cores 31'in the unfolded state. That is, FIG. 12 shows individual punched cores 31'at the timing of punching from the steel sheet.

As shown in FIG. 12, each punched core 31'in the deployed state includes a disk-shaped portion (hereinafter referred to as "disk portion") 41'. In the figure, D'indicates the inner diameter of the disk portion 41'.

N claw-shaped portions 46'are provided on the inner peripheral portion of the disk portion 41'. The individual claw-shaped portions 46'are provided so as to project with respect to the inner peripheral portion of the disc portion 41'. That is, the N claw-shaped portions 46'are provided in a reverse radial pattern. The root portion of each claw-shaped portion 46'is continuous with the inner peripheral portion of the disc portion 41'.

Next, the portion 47'between the root portion of each claw-shaped portion 46'and the inner peripheral portion of the disk portion 41' (hereinafter referred to as "first bent portion") 47'is bent. Next, a portion (hereinafter referred to as "second bent portion") 48'between the outer half portion 41'_1 of the disc portion 41'and the inner half portion 41'_2 of the disc portion 41' is bent. In FIG. 12, each first bent portion 47'is indicated by a broken line, and the second bent portion 48'is indicated by a broken line.

At this time, the direction in which each first bent portion 47'is bent is the same as the direction in which the second bent portion 48'is bent. Further, the angle at which each first bent portion 47'is bent is 90 ° or approximately 90 °. The angle at which the second bent portion 48'is bent is 90 ° or approximately 90 °.

In this way, each punched core 31'is completed. FIG. 13 shows the individual punched cores 31'in the finished state.

That is, the outer half portion 41'_1 of the disk portion 41'in the unfolded state corresponds to the back yoke portion 24'in the stator core 3'. Further, the inner half portion 41''2 of the disk portion 41 ′ in the unfolded state corresponds to the upper end magnetic path portion 22 ′ or the lower end magnetic path portion 23 ′ in the stator core 3 ′. Further, the N claw-shaped portions 46'in the deployed state correspond to the magnetic pole portions 21'in the stator core 3'.

The manufacturing method of the stator core 3'is the same as the manufacturing method of each stator core 3. Therefore, detailed description thereof will be omitted.

Next, a problem in a stepping motor using the above-mentioned comparative stator core (hereinafter referred to as "first comparative stator core") 2'(hereinafter referred to as "first comparative stepping motor") will be described. Further, the effect of the stepping motor 1 on the first comparative stepping motor will be described.

First, in a motor usually having a non-claw pole type stator core (for example, a stator core using a laminated steel plate), the size of the stator in the axial direction is increased and the size of the rotor in the axial direction is increased. The size of the individual magnetic poles in the axial direction can be increased. As a result, the amount of magnetic flux received by the stator from the rotor can be increased. As a result, the output torque of the motor can be improved. This also applies to a stepping motor having a claw pole type stator core.

However, in the first comparative stator core 3', the length L'of each claw-shaped portion 46'is limited by the inner diameter D'of the disc portion 41'(see FIG. 12). Therefore, it is difficult to increase the length L'of each claw-shaped portion 46'. That is, it is difficult to increase the size of each magnetic pole in the axial direction. As a result, in the first comparative stepping motor, there is a problem that it is difficult to improve the output torque.

On the other hand, in the stepping motor 1, there is no such limitation (see FIG. 5). Therefore, it is easy to increase the length L of each claw-shaped portion 46. Further, it is easy to increase the width W of the band-shaped portion 41. Therefore, it is easy to increase the size of each magnetic pole in the axial direction. Thereby, the output torque can be improved.

Second, the overall shape of each punched core 31'in the unfolded state is a substantially circular shape (see FIG. 12). Therefore, in the first comparative stepping motor, there is a problem that it is difficult to improve the yield in punching of the steel plate when manufacturing the stator core 3'.

On the other hand, the overall shape of each punched core 31 in the deployed state is substantially strip-shaped (see FIG. 5). Therefore, in the stepping motor 1, the yield in punching of the steel sheet can be improved as compared with the stepping motor for the first comparison.

Third, in each punched core 31', the shape of the second bent portion 48'is annular (see FIG. 12). As a result, when the second bent portion 48'is bent, the outer half portion 41'_1 of the disk portion 41'is compressed in the rotation direction (that is, the circumferential direction). There is a problem that magnetic deterioration occurs due to such compression.

On the other hand, in each punched core 31, the shape of the second bent portion 48 is linear (see FIG. 5). Thereby, when the second bent portion 48'is bent, it is possible to avoid the occurrence of such compression. As a result, the occurrence of magnetic deterioration can be suppressed.

Fourth, in the first comparative stator core 3', there is no interface corresponding to the interfaces I_1 and I_2. Therefore, a magnetic path along the rotation direction (that is, the circumferential direction) may be formed in each of the upper end magnetic path portion 22'and the lower end magnetic path portion 23'. Due to such a magnetic path, magnetic flux leakage with respect to the magnetic path P1'occurs. As a result, in the first comparative stepping motor, there is a problem that the output torque is lowered.

On the other hand, in each stator core 3, interfaces I_1 and I_2 are present. As a result, it is possible to suppress the formation of the magnetic path P2 along the rotation direction (that is, the circumferential direction) in each of the upper end magnetic path portion 22 and the lower end magnetic path portion 23 (see FIG. 14). As a result, it is possible to suppress the occurrence of magnetic flux leakage due to the magnetic path P2. As a result, it is possible to suppress a decrease in output torque as compared with the first comparative stepping motor.

Next, a problem in a stepping motor (hereinafter referred to as "second comparative stepping motor") using the stator core described in Patent Document 1 (hereinafter referred to as "second comparative stator core") will be described. Further, the effect of the stepping motor 1 on the second comparative stepping motor will be described.

First, the second comparative stator core is composed of one punched core (see, for example, FIGS. 1 to 5 of Patent Document 1). By bending the strip-shaped portion of the one punched core, the back yoke portion, the upper end magnetic path portion, and the lower end magnetic path portion are formed.

Here, the upper end magnetic path portion is formed by bending the strip-shaped portion, then the coil is inserted, and then the lower end magnetic path portion is formed by bending the strip-shaped portion (for example, the figure of Patent Document 1). 4 and FIG. 5). Therefore, there is a problem that a force is applied to the coil when the strip-shaped portion is bent to form the lower end magnetic path portion. Alternatively, there is a problem that it is required to provide a structure (for example, a receiving portion for the coil) for avoiding applying such a force to the coil.

On the other hand, each stator core 3 is a combination of two punched cores 31_1 and 31_2 (see FIG. 3). This eliminates the need to bend the steel plate with the corresponding coil 4 inserted when manufacturing the individual stator cores 3. Therefore, it is possible to avoid applying the above-mentioned force to the individual coils 4.

Second, in the second comparative stator core, there is no interface corresponding to the interfaces I_1 and I_2. Therefore, as in the case of the first comparative stator core 3', there is a problem that the output torque is lowered due to the magnetic flux leakage.

On the other hand, in each stator core 3, the occurrence of magnetic flux leakage due to the magnetic path P2 can be suppressed as described above. As a result, it is possible to suppress a decrease in output torque as compared with the second comparative stepping motor.

Thirdly, in the second comparative stator core, when the strip-shaped portion is bent to form the upper end magnetic path portion, the portion of the strip-shaped portion corresponding to the upper end magnetic path portion is in the rotation direction (that is, the circumference). (Direction) is compressed. Further, when the strip-shaped portion is bent to form the lower end magnetic path portion, the portion of the strip-shaped portion corresponding to the lower end magnetic path portion is compressed in the rotation direction (that is, the circumferential direction). There is a problem that magnetic deterioration occurs due to such compression.

On the other hand, in each stator core 3, when the strip-shaped portion 41 of the punched core 31_1 is bent into a cylindrical shape, the individual gap portions 45 are filled, and the upper end magnetic path portion 22 is formed by the N trapezoidal portions 44. To. Further, when the strip-shaped portion 41 of the punching core 31_2 is bent into a cylindrical shape, the individual gap portions 45 are filled, and the lower end magnetic path portion 23 is formed by the N trapezoidal portions 44. This makes it possible to avoid the above-mentioned compression. As a result, the occurrence of magnetic deterioration can be suppressed.

Next, regarding the problem in the stepping motor (hereinafter referred to as "third comparative stepping motor") using the stator core described in the following Reference 1 (hereinafter referred to as "third comparative stator core"). explain. Further, the effect of the stepping motor 1 on the third comparative stepping motor will be described.

[Reference 1]
Japanese Unexamined Patent Publication No. 6-86528

First, the third comparative stator core is provided with a coil on the outer peripheral portion thereof (see, for example, FIG. 2 of Reference Document 1). Further, the third comparative stator core does not have a portion corresponding to the upper end magnetic path portion 22, a portion corresponding to the lower end magnetic path portion 23, and a portion corresponding to the back yoke portion 24. That is, in the third comparative stator core, a rectangular annular magnetic path is not formed.

Therefore, the third comparative stepping motor has a problem that the output torque is lower than that of the stepping motor having a stator core in which a rectangular annular magnetic path is formed. In addition, there is a problem that it is large in the axial direction.

On the other hand, in the stepping motor 1, each stator core 3 has an upper end magnetic path portion 22, a lower end magnetic path portion 23, and a back yoke portion 24. Further, a rectangular annular magnetic path P1 is formed in each stator core 3. As a result, the output torque can be improved as compared with the third stepping motor for comparison. In addition, it is possible to reduce the size in the axial direction.

Secondly, in the third stepping motor for comparison, two pieces are provided by the first punched steel plate (comb-shaped strip (50)) and the second punched steel plate (comb-shaped strip (58)). A portion of the stator core that functions as the first stator core is configured. Further, the second punched steel plate (comb-shaped strip (58)) and the third punched steel plate (comb-shaped strip (63)) fulfill the function of the second stator core of the two stator cores. The part is composed. That is, one punched steel plate (comb-shaped strip (58)) is partially shared by two stator cores. This causes magnetic flux leakage between the stator cores. As a result, there is a problem that the output torque is lowered.

On the other hand, in the stepping motor 1, one punched steel plate is not shared by the two stator cores 3_1 and 3_2. As a result, it is possible to suppress the occurrence of magnetic flux leakage between the stator cores 3_1 and 3_2. As a result, it is possible to suppress a decrease in output torque. In other words, the efficiency of the stepping motor 1 can be improved.

Next, a modification of the stator core 3 in each stator 2 will be described.

The protruding direction of each claw-shaped portion 46 in the deployed state is not limited to the example shown in FIG. That is, the protruding direction of each claw-shaped portion 46 in the deployed state is not limited to the direction orthogonal to the longitudinal direction of the strip-shaped portion 41.

For example, as shown in FIG. 15, each claw-shaped portion 46 may be provided so as to be inclined with respect to the longitudinal direction of the strip-shaped portion 41. In other words, the longitudinal direction of each claw-shaped portion 46 may be inclined with respect to the longitudinal direction of the strip-shaped portion 41. In this case, the inclination angle φ of each claw-shaped portion 46 with respect to the longitudinal direction of the strip-shaped portion 41 in the deployed state is set to a predetermined value.

In this case, in each stator core 3, each claw-shaped portion 46 is inclined with respect to the rotation direction. As a result, it is possible to suppress the generation of pulsation in the rotation of the rotor 5. That is, when the rotor 5 rotates, it is possible to suppress the rotation speed of the rotor 5 from fluctuating with time. As a result, the rotation of the rotor 5 can be smoothed.

The shape of each claw-shaped portion 46 is not limited to the example shown in FIG. 5 or the example shown in FIG. For example, in the stepping motor 1, it may be required to improve the ability to stop the rotation of the rotor 5. In such a case, the individual claw-shaped portions 46 may have a shape that can realize the improvement of such ability. Further, for example, the shape of each claw-shaped portion 46 may gradually become thinner from the root portion to the tip portion (see FIG. 5 or FIG. 15), or may have a certain thickness. May be.

Next, another modification example of the stator core 3 in each stator 2 will be described.

As described above, the shape of each gap 45 is wedge-shaped (that is, V-shaped). Here, the shape of each gap 45 is not limited to the example shown in FIG. For example, the shape of each gap portion 45 may be inclined with respect to the longitudinal direction of the strip-shaped portion 41. In other words, where the shape of each gap 45 is wedge-shaped (that is, V-shaped), even if the longitudinal direction of each gap 45 is inclined with respect to the longitudinal direction of the strip 41. good.

In this case, in each stator core 3, the direction of each magnetic pole with respect to the rotation direction can be controlled by the direction of such inclination and the angle of such inclination. As a result, for example, the output torque in one direction of the rotation direction (hereinafter referred to as "first direction") is changed to the output torque in the other one direction of the rotation direction (hereinafter referred to as "second direction"). It can be made larger than that.

For example, in an actuator having a stepping motor 1, a spring load may be provided at the tip of the output unit. In this case, the rotation of the rotor 5 with respect to the first direction counteracts the applied load. On the other hand, the rotation of the rotor in the second direction is assisted by the spring. Therefore, it is required to increase the output torque in the first direction as compared with the output torque in the second direction. By inclining the shape of each gap 45, such a requirement can be met.

In addition, various modifications can be adopted for the shape of each gap 45. For example, there is a gap between each of the two trapezoidal portions 44 adjacent to each other in the completed state due to the large opening angle in the shape of the individual gap portions 45 or the large width of the individual gap portions 45. It may be a trapezoid. As a result, the occurrence of magnetic flux leakage due to the magnetic path P2 can be further suppressed.

The two punched cores 31_1 and 31_2 in the individual stator cores 3 may have partially different shapes.

For example, the two punched cores 31_1 and 31_2 may have different widths W of the strips 41. That is, the strip 41 in one of the two punched cores 31_1 and 31_2 is wide, and the strip 41 in any one of the two punched cores 31_1 and 31_2 is narrow. May be. These widths W may be set to a value at which the back yoke portion 24 can be formed.

Further, for example, as shown in FIG. 16, in at least one of the two punched cores 31_1 and 31_2, N trapezoidal portions 44 are provided on the first side portion of the strip-shaped portion 41, and the strip-shaped portion 44 is provided. A notch-shaped recess 49 may be provided on the other side portion (hereinafter referred to as “second side portion”) of the 41. This makes it possible to facilitate the connection between the corresponding coil 4 and the connection plate (not shown). Alternatively, the connection between the corresponding coil 4 and the connector portion 14 can be facilitated. That is, the connecting member can be passed through the recess 49.

As described above, the stepping motor 1 according to the first embodiment is a stepping motor 1 including a claw pole type stator core 3, the stator core 3 uses a punching core 31, and the punching core 31 is a punching core 31. In the deployed state, a band-shaped portion 41 corresponding to the back yoke portion 24 of the stator core 3, a plurality of trapezoidal portions 44 corresponding to the upper end magnetic path portion 22 or the lower end magnetic path portion 23 of the stator core 3, and a plurality of trapezoidal portions 44. A gap portion 45 provided between the trapezoidal portions 44 adjacent to each other, and a plurality of claw-shaped portions 46 corresponding to the magnetic pole portions 21 of the stator core 3 are provided. As a result, a rectangular annular magnetic path P1 can be formed. As a result, the stepping motor 1 can be downsized in the axial direction. In addition, it is possible to suppress the occurrence of magnetic deterioration due to the compression of the steel sheet, and it is also possible to suppress the occurrence of magnetic flux leakage due to the magnetic path P2. As a result, the efficiency of the stepping motor 1 can be improved.

Further, in the unfolded state, the punched core 31 is formed between the first bent portion 47 provided between the individual claw-shaped portions 46 and the corresponding trapezoidal portions 44, and between the individual trapezoidal portions 44 and the strip-shaped portions 41. A second bent portion 48 provided is provided. As a result, in each punched core 31, a U-shaped (that is, U-shaped) magnetic path formed by substantially dividing the rectangular annular magnetic path P1 into two can be formed.

Further, a concave portion 42 for connection is provided at the first end portion of the strip-shaped portion 41, and a convex portion 43 for connection is provided at the second end portion of the strip-shaped portion 41. By engaging the concave portion 42 with the convex portion 43, the connection between the first end portion of the strip-shaped portion 41 and the second end portion of the strip-shaped portion 41 can be strengthened.

Further, since each first bent portion 47 is bent, the second bent portion 48 is bent, and the strip-shaped portion 41 is bent in a cylindrical shape, the back yoke portion 24 and the upper end thereof are bent. The magnetic path portion 22, the lower end magnetic path portion 23, and the magnetic pole portion 21 are formed. By adopting such a structure, the degree of freedom in design is increased with respect to the width W of the strip 41, the shape of each gap 45, the shape of each claw 46, the length L of each claw 46, and the like. Can be improved. With such a design, for example, the output torque of the stepping motor 1 can be improved, or the cogging in the stepping motor 1 can be reduced.

In the disclosure of the present application, it is possible to modify any component of the embodiment or omit any component of the embodiment within the scope of the disclosure.

The stepping motor according to the present disclosure can be used as an actuator, for example.

1 stepping motor, 2 stator, 2_1 stator, 2_2 stator, 3 stator core, 3_1 stator core, 3_2 stator core, 4 coil, 4_1 coil, 4_2 coil, 5 rotor, 6 rotor magnet, 7 magnet holder, 8 output shaft, 9 housing, 10 bracket, 11 housing part, 12 sealing material, 13_1 bearing, 13_1 bearing, 14 connector part, 21 magnetic pole part, 22 upper end magnetic path part, 23 lower end magnetic path part, 24 back yoke part, 31 punched core, 31_1 punched core , 31_2 punched core, 41 strip-shaped part, 42 concave part, 43 convex part, 44 trapezoidal part, 45 gap part, 46 claw-shaped part, 47 first bent part, 48 second bent part, 49 concave part.

Claims

A stepping motor equipped with a claw pole type stator core.
The stator core uses a punched core.
The punched core is in the deployed state.
The band-shaped portion corresponding to the back yoke portion of the stator core and the strip-shaped portion
A plurality of trapezoidal portions corresponding to the upper end magnetic path portion or the lower end magnetic path portion of the stator core, and
A gap portion provided between the trapezoidal portions adjacent to each other among the plurality of trapezoidal portions,
A stepping motor including a plurality of claw-shaped portions corresponding to the magnetic pole portions of the stator core.
The punched core is in the deployed state.
A first bent portion provided between each of the claw-shaped portions and the corresponding trapezoidal portion,
The stepping motor according to claim 1, further comprising a second bent portion provided between each trapezoidal portion and the strip-shaped portion.
The first aspect of claim 1, wherein a concave portion for connection is provided at the first end portion of the strip-shaped portion, and a convex portion for connection is provided at the second end portion of the strip-shaped portion. Stepping motor.
The back yoke portion and the upper end magnetism are formed by bending each of the first bent portions, bending the second bent portion, and bending the strip-shaped portion into a cylindrical shape. The stepping motor according to claim 2, wherein the road portion, the lower end magnetic path portion, and the magnetic pole portion are formed.
The stepping motor according to claim 1, wherein in the deployed state, each of the claw-shaped portions is inclined with respect to the longitudinal direction of the strip-shaped portion.
The stepping motor according to claim 1, wherein in the deployed state, the shape of each of the gap portions is inclined with respect to the longitudinal direction of the strip-shaped portion.
In the unfolded state, a plurality of the trapezoidal portions are provided on the first side portion of the strip-shaped portion, and a notch-shaped recess is provided on the second side portion of the strip-shaped portion. The stepping motor according to claim 1.