JPH0736688B2 - Stepping motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of a stepping motor capable of achieving high efficiency by reducing a drive current, downsizing of a motor outer shape, and the like.

[Conventional technology]

FIG. 2 shows the structure of a variable reluctance type multi-phase cascade type stepping motor as an example of a conventional stepping motor. In FIG. 2, (a) is a front view seen from the axial direction, and (b) is a side view thereof. In this stepping motor, as shown in FIG. 2 (b), each phase 10A, 10B ... Is arranged along the main shaft 1 in one phase and one stage. Each phase 1
As shown in FIG. 2 (a), the stators 14 of 0A, 10B ...
A stator annular portion 14E is formed so as to surround the rotor 20, and salient poles 14A, 14 are formed at equal intervals on the inner peripheral surface of the stator annular portion 14E.
B, 14C, 14D are formed, and drive coils 16A, 16B, 16C, 1 are formed there.
6D is wrapped around each. Drive coil 16A, 16B, 16C, 16
Ds are connected in series and supplied with a current from the terminal 18 to be excited. When the drive coils 16A, 16B, 16C, 16D are excited, the salient poles 14A, 14B, 14C, 14D are alternately magnetized into N pole and S pole,
Magnetic flux is generated as shown by the dotted line in the middle of FIG.

The rotor 20 is formed in a cylindrical shape. Stator salient pole 14A,
As shown in the enlarged view of part A in FIG. 2 (a), stator teeth 14a and rotor teeth 2 are provided on the facing surfaces of 14B, 14C, 14D and the rotor 20.
0a is formed by the same pitch. Therefore, when the drive coils 14A, 14B, 14C, 14D are excited, the rotor 20 stops at the position where the magnetic resistance is minimized, that is, the position where the stator teeth 14a and the rotor teeth 20a coincide.

The stator 14 has salient poles of each phase 10A, 10B ... Arranged in parallel to the main shaft 1, but the rotor teeth 14a have a predetermined twist angle α with respect to the main shaft 1, as shown in FIG. 2 (b). Is formed with. Therefore, stator teeth 14a and rotor teeth 20a
The phase relationship with and is slightly deviated for each phase 10A, 10B ... When the stator teeth 14a of the first phase 10A and the rotor teeth 20a are correctly facing each other, the stator teeth 1 of the second phase 10B 1
4a and rotor tooth 20a are slightly displaced. Therefore,
When the state where the first phase 10A is excited is switched to the state where the second phase 10B is excited, the stator tooth 14a and the rotor tooth are changed in the second phase 10B.
The rotor 20 rotates to a position where the 20a are correctly faced and stops. In this way, if the excitation of each phase 10A, 10B, ... Is turned on and off in a predetermined order, the rotor 20 can be rotated by an arbitrary number of steps.

This variable reluctance type multi-phase cascade type stepping motor has the following advantages.

The number of phases can be increased by increasing the number of stages, and a motor with high torque and high resolution can be manufactured.

Since the shape of the rotor 20 is elongated, the inertia is smaller than the torque and the response is good.

On the other hand, a disadvantage of this type is that it is inefficient because all the necessary magnetic flux is obtained from the current.

Next, FIG. 3 shows an example of a conventional four-phase hybrid stepping motor (of a type combining a variable reluctance type and a permanent magnet type). (A) is the front view seen from the axial direction, (b) is the side view. This stepping motor is, as shown in FIG.
The two stages are composed of two stages, 22A and 22B, and the first stage 22 has
A phase, C phase, and B phase, C phase are formed in the second stage.

The rotor 26 is divided into a first stage rotor 26A and a second stage rotor 26B, which are joined by a permanent magnet 28. Therefore, the first-stage rotor 26A is magnetized to the N pole, and the second-stage rotor 26B is S-magnetized.
It is magnetized to the pole. There are rotor teeth 26a, 2 on rotors 26A, 26B.
6b are formed with a phase shift of 1/4 pitch from each other.

The first stage 22A includes a stator 30 as shown in FIG.
Has four salient poles 30A, 30B, 30C, 30D, on which drive coils 32A, 32B, 32C, 32D are respectively wound. The drive coils 32A and 32C are connected in series to form an A-phase drive coil, and a current is supplied from the terminal 34. Drive coil 32
B and 32D are connected in series to form a C-phase drive coil,
Current is supplied from terminal 36. The rotor teeth 26a and the stator teeth 30a are divided into A phase (salient poles 30A and 30C) and C phase (salient poles 30B and 30) as shown in the enlarged view of the A part and the enlarged view of the B part in FIG.
It is shifted by 1/2 pitch with D), and when facing in A phase, it is in a completely displaced position in C phase. The second stage 22B is also constructed in the same manner as the first stage 22A, and B phase and D phase are formed.

Now, the A-phase and C-phase drive coils 32A, 32B, 32C, 32 of the first stage 22
When a current is applied to D so that it is excited with the polarity shown in Fig. 3 (a), the magnetic flux generated by the permanent magnet 28, which is discharged from the rotor 26A, and the magnetic flux generated by the drive coils 32A, 32C are strengthened in the A phase. And a strong magnetic force works as a result (enlarged view of part A). On the other hand, in phase C, the magnetic forces do not work because they cancel each other out (enlarged view of part B). Therefore, the phase A rotor teeth
The rotor 26 stops at the position where the stator teeth 30a face the 26a.

Next, the excitation of the first stage 22A is stopped, and in the second stage 22B, in the B phase, a current is supplied so that the magnetic flux generated by the permanent magnet 28 that is fed out from the rotor 26B and the magnetic flux generated by the drive coil strengthen each other. If currents are supplied so as to cancel each other in the phase, the rotor 26 stops at the position where the rotor teeth 26b and the stator teeth face each other in the B phase.

Next, by stopping the excitation of the second stage 22B and supplying a current to the A and C phases of the first stage 22A with the opposite polarity to the above, the position where the rotor tooth 26a and the stator tooth 30a face each other in the C phase. At the rotor
26 will stop.

Further, if the excitation of the first stage 22A is stopped and a current is supplied to the B and D phases of the second stage 22B with the opposite polarity to the above,
The rotor 26 stops at the position where the rotor tooth 26a and the stator tooth 30a face each other in the D phase. In this way, by changing the directions of the A-phase to D-phase currents in a predetermined order, the rotor 26
Can be rotated by any number of steps.

In this hybrid type stepping motor, since a part of the required magnetic flux is obtained from the permanent magnet 28, a larger torque can be obtained with the same current value as in the variable reluctance type shown in FIG. However, it has the following drawbacks.

Since it is very difficult to make a multi-stage cascade type,
It is difficult to manufacture a motor with high resolution and high torque. That is, in the case of FIG. 2, a motor having an arbitrary number of stages can be easily manufactured only by changing the twist angle α of the rotor teeth 20a, but in the case of FIG. 3, three stages are used because the NS pole of the permanent magnet is used. Or you can't make 5-tiered ones. For example,
Considering the case of four stages, it is difficult to integrate them because the rotor teeth are different for each stage, and it is the same labor as manufacturing two two-stage motors and adjusting the phase of each rotor. Takes. In other words, as the number of stages increases, the difficulty of manufacturing increases dramatically, which is not practical.

Since the rotor 26 has the permanent magnet 28, the weight of the rotor 26 is large, and the outer diameter is large compared to the torque.
Large inertia and poor responsiveness.

[Problems to be Solved by the Invention] The present invention solves the drawbacks in the above-mentioned conventional techniques,
An object of the present invention is to provide a stepping motor capable of achieving high efficiency by reducing a driving current and downsizing of a motor outer shape.

[Means for solving problems]

The present invention relates to a permanent magnet and / or a DC exciting coil, a magnetic path for guiding the magnetic flux of the permanent magnet and / or the DC exciting coil from the stator teeth to the rotor teeth, and the permanent magnet and / or the DC exciting coil. The stator is provided with a magnetic path for bypassing the magnetic flux without passing through the rotor and a drive coil for generating a magnetomotive force in the bypass magnetic path. The feature is that a plurality of phases are provided while being shifted.

[Action]

According to the above-mentioned solution means of the present invention, when a current is passed through the drive coil of the detour so as to cancel the magnetic flux due to the permanent magnet and / or the DC excitation coil, the magnetic flux of the permanent magnet and / or the DC excitation coil and the detour circuit. When the magnetic flux that is the combination of the magnetic fluxes of the drive coil passes through the rotor and the rotor is excited, and the supply of the current to the drive coil of the bypass circuit is stopped, the magnetic flux of the permanent magnet and / or the DC excitation coil passes through the bypass circuit. Then, the rotor does not pass through and the rotor is in a non-excited state. Therefore, in the excited state, the magnetic flux of the permanent magnet and the magnetic flux of the drive coil are added to drive the rotor, so that the current of the drive coil can be reduced. In addition, even if a DC exciting coil is used, the current supplied to the DC exciting winding does not need to be turned on and off, so it is only necessary to connect the DC exciting windings of each phase in series and always apply a constant current. In the case of a multi-phase motor, the current as a whole is smaller than that of a conventional VR type motor, and the drive circuit can be easily manufactured.

[Embodiment 1] FIG. 1 is a view showing a basic embodiment of the present invention, in which one step of a stepping motor constituted by cascade connection of one phase and one step is viewed from the axial direction. is there.

In this stepping motor, a stator 13 is formed so as to surround the rotor 11, and two salient poles 13A and 13B are formed on the inner peripheral surface of the stator 13 so as to face the rotor 11 and face each other. On the outer peripheral surface of the rotor 11 and the surfaces of the salient poles 13A and 13B facing the rotor 11, as shown in FIG.
13Aa and 13Ba are formed respectively.

A permanent magnet 15 is incorporated in the stator portion 13C on the left side of the salient poles 13A and 13B. Also, the right stator part 13
A drive coil 17 is wound around D. A current is supplied to the drive coil 17 from a terminal 19 so as to be excited in a direction in which the magnetic flux generated by the permanent magnet 15 is canceled.

According to the configuration of FIG. 1, when no current is supplied to the drive coil 17, most of the magnetic flux generated by the permanent magnet 15 is the stator outer peripheral portion 13C, as shown by the chain double-dashed line 21 in FIG. 13D
Through the salient poles 13A, 13B to the rotor 11. Therefore, the rotor 11 is not strongly attracted. On the other hand, when current is supplied to the drive coil 17, the magnetic flux generated by the drive coil 17 is generated in the direction in which the magnetic flux generated by the rotor 11 is canceled out.
The magnetic flux generated by 15 passes through a path from the salient pole 13A to the salient pole 13B via the rotor 11 as indicated by alternate long and short dash lines 23 and 25 in FIG. Therefore, the rotor 11 is strongly attracted and stops at the position where the rotor teeth 11a and the stator teeth 13Aa, 13Ba coincide.

In this way, by turning the current on and off, the rotor
The magnetic flux passing through 11 can be turned on and off. That is, in the configuration shown in FIG. 1, the salient poles 13A and 13B serve as magnetic paths for guiding the magnetic flux of the permanent magnet 15 to the rotor 11, and the stator right portion 13D serves as magnetic paths for diverting the magnetic flux of the permanent magnet 15. Two magnetic paths are switched by turning on and off the drive coil 17 provided.

In addition, according to the configuration of FIG. 1, since the magnetic flux from the permanent magnet 15 acts in addition to the magnetic flux from the winding wire 17 at the time of supplying current, a stronger torque can be obtained as compared with the excitation by only the winding wire 17.

Since the operation for one stage is performed as described above, the other stages are similarly configured, and the phase relationship between the stator teeth and the rotor teeth in each of these stages is set slightly different for each stage and set. The rotor can be rotated by an arbitrary number of steps by sequentially exciting the drive coils of the stages alternately.

Here, the above operation will be described with a magnetic circuit.

FIG. 4 shows the rotor 11 and the stator 13 of FIG. 1 in a magnetic circuit. Each symbol in FIG. 1 has the following meaning.

E _p : Magnetomotive force due to permanent magnet 15 E _c : Magnetomotive force due to driving coil 17 R _g : Magnetic resistance of the gear between rotor 11 and stator 13 r1: Magnetic resistance of left stator portion 13C r2: Right stator portion 13D Magnetoresistance In such a magnetic circuit, the same rule as in the electric circuit is approximately established, and the magnetic flux is the magnetomotive force divided by the magnetic resistance as in the case of the current.

Here, the state when the current in the drive coil 17 is not flowing from the E _{c =} 0, the magnetic flux i _p of the permanent magnet 15 magnetic resistance r1
And R _g , r2 in parallel are added, so Becomes

Further, the magnetic flux i _g passing through R _g and the magnetic flux i _c passing through r2 are
Since i _p1 is divided by the reciprocal ratio of R _g and r2, Becomes Here, in the embodiment of FIG. 1, the stator 13 is bilaterally symmetric, and it can be considered that r1≈r2. Therefore, r = r1 = r2.

Furthermore, since R _g >> r is usually satisfied, the formula (1) is Therefore, the expressions (2) and (3) are as follows: i _g ≈O i _c ≈i _p1 . That is, most of the magnetic flux i _p1 generated by the permanent magnet 15 passes through the stator right side portion 13D, which is a detour, and the rotor 11
It does not pass through the salient poles 13A and 13B, which are the supply paths to the. Therefore, the rotor 11 is not strongly attracted to the stator 13.
The above corresponds to the case of non-excitation of this phase.

Next, when a current is supplied to the drive coil 17 so that E _c = E _p , the circuit of FIG. 4 becomes symmetrical, so that i _g , i
_p2 is Becomes That is, the magnetic flux i _p2 generated by the permanent magnet 15 and the winding
The magnetic flux i _c generated by 17 is added and guided to the rotor 11, and the rotor 11 is rotated to a position where the rotor teeth 11a and the stator teeth 13Aa, 13Ba coincide. The above is the excitation state of this phase.
In the actual design, the magnetomotive force E _p of the permanent magnet 15 is determined so that i _p2 is sufficient to produce the required torque.

If r is not negligible with respect to R _g in the case of non-excitation, the direction of the current supplied to the drive coil 17 is reversed and the direction of E _c in FIG. 4 is reversed, i
_It suffices to find the condition that _g = O. This result is E _c =-
It is E _p , and a current of the same magnitude as in the case of excitation will flow in the opposite direction.

[Embodiment 2] FIG. 5 shows an embodiment which is a further development of the embodiment shown in FIG. It has two permanent magnets and two drive coils.
They are used individually. In FIG. 5, (a) is a front view seen from the axial direction, and (b) is a side view thereof.

This stepping motor has a combination of rotors and stators of one phase and one stage as shown in FIG. 5 (b).
B, ...) These are connected in cascade. The stator 42 of each phase 40A, 40B, ... As shown in FIG. 5 (a), the stator annular portion 42A formed so as to surround the rotor 44 and the inner peripheral surface of the stator annular portion 42A project at equal intervals. It is provided with four salient poles 42B, 42C, 42D, 42E formed by the above. On the outer peripheral surface of the rotor 44 and the surfaces of the salient poles 42B, 42C, 42D, 42E facing the outer peripheral surface,
Rotor teeth and stator teeth (both not shown) are respectively formed.

A portion 42A of the stator annular portion 42 located between the salient poles 42C and 42D
Drive coils 46 and 48 are respectively wound around a portion 42Ad of the stator annular portion 42 located between b and the salient poles 42E and 42B. In addition, the stator annular portion 4 located between the salient poles 42B and 42C.
Permanent magnets 50 and 52 are inserted in the illustrated polarities in the portion 42Ac of the stator annular portion 42 located between the second portion 42Aa and the salient poles 42D and 42E, respectively. The drive coils 46 and 48 are connected in series, a current is supplied from the terminal 53, and the drive coils 46 and 48 are excited in a direction of canceling the magnetic flux by the permanent magnets 50 and 52.

According to the above configuration, when the drive coils 46 and 48 are not excited, the magnetic flux of the permanent magnets 50 and 52 largely bypasses the stator annular portion 42 as indicated by the two-dot chain line arrow 56. Therefore, the rotor 44 is only slightly guided. Therefore,
The rotor 44 is not strongly attracted. On the other hand, when the drive coils 46, 48 are excited, the magnetic flux generated by the drive coils 46, 48 is generated in the direction of canceling the magnetic flux generated by the permanent magnets 50, 52. As shown in FIG. Also, drive coil 4
The magnetic flux of 6,48 is also indicated by the dashed line arrow 60
Pass through. Therefore, the rotor 44 stops at the position where the rotor teeth and the stator teeth match. At this time, drive coil 4
In addition to the magnetic flux generated by 6,48, the magnetic flux generated by the permanent magnets 50, 52 passes through the rotor 44, so that a larger torque can be obtained as compared with the excitation by only the drive coils 46, 48.

In this way, the current supplied to the drive coils 46 and 48 is turned on,
By turning off, the magnetic flux passing through the rotor 44 can be turned on and off. That is, the configuration of FIG.
C and 42B are magnetic paths that guide the magnetic flux of the permanent magnet 50 to the rotor 44, and salient poles 42D and 42E are magnetic paths that guide the magnetic flux of the permanent magnet 52 to the rotor 44. In addition, the stator annular portion 42 has permanent magnets 50, 52.
The magnetic paths are detoured, and these magnetic paths are switched by turning on and off the drive coils 46 and 48 arranged in this detour.

The first stage 40A has been described above, but the other stages 40B,
... is also configured in the same way. As shown in FIG. 5 (b), the stators of the respective stages 40A and 40B are arranged so as to be offset by 90 ° from each other so that the drive coils 46 and 48 do not collide with each other.

As shown in FIG. 5 (b), the rotor teeth 44A are formed with a predetermined twist angle α with respect to the spindle 1. As a result, a slight shift is formed in the phase relationship between the rotor teeth 44A and the stator teeth of each stage. Therefore, each stage 40A, 40
The rotor 44 can be rotated by an arbitrary number of steps by sequentially exciting B, ...

[Third Embodiment] In the second embodiment, two permanent magnets and two drive coils are used for each stage, but it is also possible to use more than that. FIG. 6 shows three permanent magnets 6 as an example.
0,62,64 and three coils 66,68,70 are used. Drive coils 66,68,70 are permanent magnets 60,62,64
It is excited in the direction to cancel the magnetic flux due to. Drive coil 6
When current is not supplied to 6,68,70, permanent magnets 60,62,6
The magnetic flux of 4 has a stator annular portion 74
Through, the rotor 76 is not strongly attracted. On the other hand, when a current is supplied to the drive coils 66, 68, 70, the magnetic flux of the drive coils 66, 68, 70 is generated in the direction of canceling the magnetic flux of the permanent magnets 60, 62, 64, so that the permanent magnets 60, 62 , 64 and the magnetic fluxes of the drive coils 66, 68, 70 are guided to the rotor 76 through the stator salient poles 82, 84, 86, 88, 90, 92, as indicated by alternate long and short dash lines 78, 80, respectively. As a result, the rotor 76 is attracted to the salient stator poles, and the rotor 76 stops at the position where the rotor teeth and the stator teeth match. Therefore, a plurality of combinations of the stator and rotor 76 should be arranged in the axial direction, the phase relationship between the stator teeth and the rotor teeth should be slightly shifted for each phase, and the drive coils for each phase should be sequentially excited alternately. Thus, the rotor 76 can be rotated by an arbitrary number of steps.

[Embodiment 4] In the embodiment shown in FIG. 1, the stator salient poles 13A and 13B are sandwiched, the permanent magnet 15 is installed in the annular portion 13C on the left side, and the winding 17 is provided on the annular portion 13D on the right side. As shown in FIG. 7, salient poles 96 and 98 are formed on the left side portion of the stator 101, the rotor 94 is arranged between these salient poles 96 and 98, and the permanent magnet 100 is placed in the central portion of the stator 101. The same effect can be obtained by installing the drive coil 102 on the right side of the stator 101. A chain double-dashed line 104 in FIG. 7 shows the flow of magnetic flux by the permanent magnet 100 when the drive coil 102 is not excited. The alternate long and short dash lines 106 and 108 indicate the drive coil 1
The flow of the magnetic flux by the permanent magnet 100 and the flow of the magnetic flux by the drive coil 102 when 02 is excited are shown respectively. That is, when no current is supplied to the drive coil 102, most of the magnetic flux generated by the permanent magnet 100 passes through the bypass path on the right side of the stator and is hardly guided to the rotor 94. Further, when an electric current is passed through the drive coil 102, the magnetic flux generated by the drive coil 102 is generated in the direction of canceling the magnetic flux generated by the permanent magnet 100, so that both the magnetic flux generated by the drive coil 102 and the magnetic flux generated by the permanent magnet 100 are guided to the rotor 94. In this way, excitation and de-excitation of this phase are performed by turning on and off the current to the drive coil 102.

[Embodiment 5] In the embodiment of FIG. 8, the arrangement of the permanent magnet 100 and the drive coil 102 in FIG. 7 is exchanged. Drive coil 1
When the electric current is not supplied to 02, the magnetic flux of the permanent magnet 100 is bypassed as shown by the chain double-dashed line 110 and is not guided to the rotor 94. When an electric current is supplied to the drive coil 102, the magnetic flux of the drive coil 102 is generated in the direction of canceling the magnetic flux of the permanent magnet 100, so that these magnetic fluxes are both guided to the rotor 94 as indicated by the chain lines 112 and 114, respectively. As a result, the same operation as that of FIG. 7 is obtained.

[Embodiment 6] The embodiment shown in FIG. 9 is a further development of the embodiment shown in FIG. The stator surrounds the rotor 131 and has four parts 130, 132, 134, 136.
It is divided into two parts. The stator portion 130 has a seventh
Similar to the embodiment shown in the figure, it has a permanent magnet 133, a magnetic path (salient poles 130A, 130B) for supplying the magnetic flux of the permanent magnet 133 to the rotor 131, and a magnetic flux detour 130C. Other stator parts 132,134,
136 is similarly configured. Each stator part 130,132,1
Drive coils 140, 142, 144, and 146 are wound around the detours 130C, 132C, 134C, and 136C in 34 and 136, respectively. The drive coils 140 and 144 are connected in series to form a phase A drive coil, and a current is supplied from the terminal 148 to be excited in a direction in which the magnetic flux generated by the permanent magnets 133 and 137 is canceled. Drive coil 142,
146 is connected in series to form a B-phase drive coil, and terminal 1
A current is supplied from 50, and the magnets are excited in a direction of canceling the magnetic flux of the permanent magnets 135, 139.

When no current is supplied to the drive coils 140, 142, 144, 146, the magnetic flux of each permanent magnet 133, 135, 137, 139 passes through the detours 130C, 132C, 134C, 136C as shown by the chain double-dashed line, and the rotor 1
31 is not excited. When electric current is supplied to the drive coils 140, 142, 144, 146, the magnetic flux of the drive coils 140, 142, 144, 146 is changed to permanent magnets 133, 135, 137, 139.
Is generated in the direction to cancel the magnetic flux of the drive coil 140,14
The magnetic flux of 2,144,146 and the magnetic flux of the permanent magnets 133,135,137,139 both pass through the rotor 131 as shown by the one-dot chain line,
The rotor 131 is excited.

The relationship between the rotor teeth and the stator teeth is deviated between the A phase and the B phase as shown in the enlarged view of part A and the enlarged view of part B. Therefore,
The rotor 131 can be rotated by a predetermined number of steps by alternately switching between the A-phase, the B-phase, and each of the other stages for excitation.

[Embodiment 7] Although a permanent magnet is used in each of the embodiments, a DC exciting coil may be used instead.

FIG. 10 shows an example in which the permanent magnet 15 in the embodiment of FIG. 1 is replaced with a DC exciting coil 120. A direct current is always supplied to the direct-current exciting coil 120 so that the direct-current exciting coil 120 is excited with the illustrated polarity. When no current is supplied to the drive coil 17, most of the magnetic flux of the DC excitation coil 120 passes through the detour as shown by the chain double-dashed line 122 and is not guided to the rotor 11. When an electric current is supplied to the coil 17, the magnetic flux of the coil 17 is generated in a direction of canceling the magnetic flux of the DC exciting coil 120, so that these magnetic fluxes both pass through the rotor 11 as indicated by alternate long and short dash lines 124 and 126. In this way, by turning the current supplied to the coil 17 on and off, it is possible to create the excited and non-excited states of this phase.

[Embodiment 8] In each of the above-mentioned embodiments, a permanent magnet or a DC exciting coil is used, but these may be used together.

[Effect of device]

As described above, according to the present invention, the following effects can be obtained.

By obtaining the required magnetic flux from the permanent magnet, less current is required to be supplied to the drive coil in order to produce the same torque. Further, as a result, the drive circuit can be easily manufactured.

Since the number of windings is smaller than that of the conventional one, it is possible to reduce the size.

Since the rotor does not have a permanent magnet unlike the conventional hybrid type (FIG. 3), the rotor weight and outer diameter can be reduced, the inertia of the rotor can be reduced, and a multistage cascade type can be obtained.

Even if a DC exciting coil is used instead of a permanent magnet, it is not necessary to turn on and off the current supplied to the DC exciting winding.Therefore, connect the DC exciting winding of each phase in series to keep a constant current. In the case of a multi-phase motor, there is an effect that the current is generally smaller than that of the conventional VR type motor and the drive circuit can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a view showing a basic embodiment of the present invention, and is a view of a rotor and a stator as seen from the axial direction thereof. FIG. 2 is a view showing a conventional variable reluctance type multi-phase cascade type stepping motor, in which (a) is a front view as seen from the axial direction and (b) is a side view thereof. FIG. 3 is a view showing a conventional hybrid type stepping motor. (A) is a front view seen from the axial direction, and (b) is a side view thereof. FIG. 4 is a diagram showing the embodiment of FIG. 1 by a magnetic circuit. 5 to 10 are views showing other embodiments of the present invention. 13,14,30,42,74,101 …… stator, 15,50,60,62,64,10
0,133,135,137,139 …… Permanent magnets, 16A, 16B, 16C, 16D, 17,
32A, 32B, 32C, 32D, 46, 48, 60, 68, 70, 102, 140, 142, 144, 146
...... Drive coil, 120 …… DC excitation coil.

Claims (1)

[Claims] 1. A permanent magnet and / or a DC exciting coil, a magnetic path for guiding the magnetic flux of the permanent magnet and / or the DC exciting coil from stator teeth to rotor teeth, and the permanent magnet and / or the DC exciting coil. The stator is provided with a magnetic path for diverting the magnetic flux of the above without passing through the rotor, and a drive coil for generating a magnetomotive force in the bypass magnetic path. A stepping motor characterized in that a plurality of phases are provided while being shifted.