JP3357817B2 - Multi-phase PM type stepping motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-phase PM type stepping motor suitable for OA equipment such as a printer, a high-speed FAX, and a copying machine for PPC.

[0002]

2. Description of the Related Art A conventional single-phase PM stepping motor will be described with reference to FIGS. FIG.
FIG. 3 is a longitudinal sectional side view of a conventional single-phase PM stepping motor 30, in which 31 is a cylindrical rotor having NS magnetic poles formed alternately in the circumferential direction on the outer peripheral surface, and 32 is the rotation of the rotor 31. The shaft 33 is a ring-shaped stator, and is arranged so that the inner peripheral surface thereof faces the outer peripheral surface of the rotor 31 via a gap. 34 is the stator 3
3, a stator coil, 35 a stator yoke,
36a and 36b are motor mounting plates fixed to the stator yoke 35, and 37a and 37b are mounting plates 36a and
This is a bearing provided for the rotary shaft 32 provided at 36b.

Next, details of the stator 33 will be described with reference to FIG. FIG. 14 is a longitudinal sectional side view showing the stator 33 in an exploded manner. The stator yoke 35 is formed by ring-shaped one and other yoke elements 39a and 39b provided with comb-shaped pole teeth 38a and 38b extending in the axial direction along the inner peripheral surface of the stator coil 34, respectively. The pole teeth 38a and 38b are arranged so as to be adjacent to each other alternately in the circumferential direction.

[0004] The stator coil 34 includes one and the other yoke elements 39 a and 39 b and pole teeth 38.
a, bobbin 40 surrounded by a, 38b
And a ring-shaped coil 41 wound around the bobbin 40.

Next, a conventional two-phase PM stepping motor will be described with reference to FIG. FIG. 15 is a vertical sectional side view of a conventional two-phase PM stepping motor 50. In the stepping motor 50, the stator 53
Are the first and second stator portions 53a, 5
3b.

[0006]

Since the conventional single-phase PM stepping motor as described above has only one stator, the direction of rotation of the motor is determined by the pole teeth of the stator and the rotor. Equipment that requires high-speed rotation or high torque, by shifting the magnetic vermance or phase between the magnetic poles so that the rotation direction of the motor is determined, or by using a mechanical method to determine the rotation direction of the motor. Was unsuitable for

Further, according to the two-phase PM type stepping motor developed to solve these problems, the torque and the high speed can be greatly improved, but there are the following problems. (1) The number of lead wires for a coil is as large as four, and at least eight transistors are required for a drive circuit. (2) Vibration is large due to large torque ripple. (3) If a small step angle is required, a large number of pole teeth must be formed, and there is a problem in machining. (4) It is difficult to obtain a small step angle and a high torque. (5) Further, in the three-phase PM type stepping motor disclosed in Japanese Patent Application Laid-Open No. 1-259748, the phase angle of the current is 60 °, and there is a problem that the 120 ° current drive cannot be performed. An object of the present invention is to provide a multi-phase PM stepping motor that solves the above-mentioned problems (problems).

[0008]

According to a first aspect of the present invention, there is provided a stepping motor having a cylindrical shape in which N poles and S poles are alternately magnetized on an outer peripheral surface. And a stator that is disposed opposite to the N-pole or S-pole of the outer peripheral surface of the rotor with a certain gap therebetween, and the stators overlap each other in the axial direction.
Formed by three first to third stator portions joined together
Each of the stator sections includes a stator coil and the stator coil.
One and the other yoyo holding the data coil from both sides
And the stator coil from these yoke elements.
Extend axially along the inner peripheral surface of
It is formed by one and the other pole teeth of the separated comb teeth,
The pole pitch of one and the other poles of each stator is
s, the other pole tooth in each stator section
There are shifted .tau.s / 2 from one of the pole teeth, whereas, if the magnetization pitch angle of the permanent magnet is P, each stator
The position of each one or the other pole teeth in the part is 2P /
It was configured to be shifted by three angles.

A stepping motor according to a second aspect of the present invention
The three stator coils housed in the three yoke elements are coupled to three terminals, and two or three of the three stator coils are driven by a drive circuit including six transistors.
It is configured so that each of them is driven by bipolar at the same time.

[0010] The stepping motor according to claim 3 is
A rotor composed of a cylindrical permanent magnet in which N and S poles are alternately magnetized on the outer peripheral surface, and an N pole or S on the outer peripheral surface of the rotor;
Stator opposed to the pole with a certain gap
The stators are axially superimposed on each other
Formed by n (n is an odd number) first to n-th stator portions.
And each of the above-mentioned stator portions is provided with a stator coil and
One and the other holding the stator coil from both sides
A yoke element and the stator coil
Each extending in the axial direction along the inner peripheral surface of the
Formed with one and the other pole teeth of the comb teeth spaced apart from each other
And the pole tooth pitch of one and the other of
Τs, each of the stator portions has the other
Pole teeth have .tau.s / 2 shifted from one of the pole teeth, whereas, if the magnetization pitch angle of the <br/> permanent magnet is P, each of stearyl
Position of each one or each other pole tooth in the
It was configured to be shifted by P / n angle.

The stepping motor according to claim 4 is
The rotor was configured to have a hybrid structure.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a polyphase PM stepping motor according to the present invention will be described with reference to FIGS. First, the basic configuration of a three-phase PM stepping motor according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional side view showing one embodiment of a three-phase PM type stepping motor 20 of the present invention. FIG. 2 is an exploded perspective view showing one embodiment of a three-phase PM type stepping motor 20 of the present invention. It is. FIG. 3 is a development view of the stator 3 and the rotor 1 of the stepping motor 20. As shown in FIGS. 1 and 2, in the three-phase PM type stepping motor 20 according to the present embodiment, the stator 3 is overlapped with each other in the axial direction.
The first to third stator portions 3a to 3c, and the comb-shaped pole teeth 8a of the stator portions 3a to 3c,
The relative positions of 8b and the N and S magnetic poles on the outer peripheral surface of the rotor 1 are determined as shown in FIG. In FIG. 1, 2 is a rotating shaft, 4 is a stator coil, 6a and 6b are motor mounting plates, and 7a and 7b are bearings of the rotating shaft 2. In FIG. 2, reference numeral 12 denotes a motor case.

That is, when the pole teeth pitch of the pole teeth 8a and 8b of one or the other yoke elements 9a and 9b is τs, respectively, in the first to third stator portions 3a to 3c,
The other pole tooth 8b is shifted in the circumferential direction from the one pole tooth 8a by τs / 2, and the one pole tooth 8a of the second stator portion 3b is shifted to the other pole of the first stator portion 3a. The tooth 8a is shifted by τs / 3, the one pole tooth 8a of the third stator portion 3c is shifted from the other pole tooth 8a of the second stator portion 3b by τs / 3, and the other one of the first stator portion 3a is shifted by τs / 3. The pole teeth 8a are similarly shifted from the other pole teeth 8a of the third stator portion 3c by τs / 3. Further, the pitches of the north pole and the south pole of the rotor 1 are respectively τr
Τr = τs, so that the interval (pitch) P between the N pole and the S pole adjacent thereto is P = τr / 2. As a result, the stepping motor of the present invention
In the configuration, as shown in FIG.
Opposing yaw in the first, second, and third stator portions
Magnetic pole pitch between pole teeth of magnetic element (pitch between 8a and 8b)
τs / 2 .

The operation of the three-phase PM stepping motor 20 according to the present invention having the above configuration will be described with reference to FIGS. FIG. 4 shows the stator coils 4a to 4c formed by monofilar winding and their six external lead wires, and FIG. 5 shows these using six PNP transistors TR1 to TR6 and six NPN transistors TR7 to TR12. FIG. 6 shows a drive circuit diagram of the stator coils 4a to 4c, and FIG. 6 uses the drive circuit of FIG. 5 to simplify the operation of the three-phase PM type stepping motor 20 of the present invention. FIG. 4 is a waveform diagram when 4c is sequentially bipolar-driven. FIG. 7 is a development view of the pole teeth 8a and 8b of the stator portions 3a to 3c and the magnetic poles of the rotor 1 for simplifying and explaining the operation of the three-phase PM stepping motor 20 of the present invention.

In step 1 of FIG. 7, the first stator 3
a of the pole teeth 8a are all S, and the other pole teeth 8b are all N
In this case, the current is applied only to the stator coil 4a so that the magnetic pole N of the rotor 1 is attracted by the pole teeth 8a of the first stator portion 3a, and the magnetic pole S is attracted by the pole teeth 8b of N. It will be aligned as shown in the figure.

Next, in step 2 of FIG. 7, when a current is applied to the stator coil 4b so that one pole tooth 8a of the second stator portion 3b is N and the other pole tooth 8b is S, the rotor 1 The magnetic poles N and S are attracted and moved by the N of the pole teeth 8a and the S of the pole teeth 8b of the second stator portion 3b to be aligned. At this time, the magnetic pole of the rotor 1 has moved by τr / 6.

Further, in step 3 of FIG. 7, when a current is applied to the stator coil 4c so that one pole tooth 8a of the third stator portion 3c is S and the other pole tooth 8b is N, the magnetic pole of the rotor 1 is The N and S are attracted by the N of the pole teeth 8b and the S of the pole teeth 8a of the third stator portion 3c, respectively, and the rotor 1 moves one step and aligns.

Hereinafter, in steps 4, 5, and 6, the directions of the currents flowing through the stator coils 4a to 4c are reversed from those in steps 1, 2, and 3, respectively. By doing so, the rotor 1 moves as shown by the arrow, and returns to step 1 in step 7. The step angle θs at this time is τr / 6.

Next, referring to FIG. 8 to FIG.
The specific operation of the phase PM type stepping motor 20 will be described. Here, FIG. 8 is an explanatory diagram of the stator coil 4 of the three-phase PM type stepping motor 20 of the present invention, FIG. 9 is a diagram of a stator coil driving circuit, and FIG. 10 is an excitation sequence diagram of the stator coil 4. FIG. 11 shows the third embodiment of the present invention.
FIG. 7 is a development view of pole teeth 8a and 8b of stator portions 3a to 3c and magnetic poles of a rotor 1 for simplifying and explaining the operation of the phase PM type stepping motor 20.

In this embodiment, as shown in FIG. 8, the stator coils 4a to 4c are connected in a star shape to make three external leads, and each of the leads is connected to a DC power supply V as shown in FIG. PNP transistors TR13- connected in series between
Connected between TR15 and NPN transistors TR16 to TR18, an excitation signal as shown in FIG. 10 is applied to this stator coil drive circuit to bipolar-drive the first to third stator coils 4a to 4c.

That is, as shown in FIG. 11, in step 1, one pole tooth 8a of the first stator portion 3a and the other pole tooth 8b of the second stator portion 3b are all S,
The other pole tooth 8b of the second stator section 3b and the one pole tooth 8a of the second stator section 3b are all N. In step 2, the other pole tooth 8a of the second stator section 3b and the other of the third stator section 3c are formed. Are all N, and the other pole tooth 8b of the second stator portion 3b and one pole tooth 8a of the third stator portion 3c are all S. In step 3, the third stator portion 3c Of one pole tooth 8a and the other pole tooth 8b of the first stator portion 3a
, The other pole tooth 8b of the third stator portion 3c and the one pole tooth 8a of the first stator portion 3a are all N.

In steps 4 to 6, the direction of the current flowing through each of the stator coils 4a to 4c is reversed, and N and S are reversed from those in steps 1 to 3. In step 7, the process returns to step 1. The step angle θc in this embodiment is τr / 6.

FIG. 12 shows the relationship between the number P of magnetic poles of the rotor 1, the magnetic pole pitch τr, and the step angle θc of the rotor 1.

[0024]

The multi-phase PM type stepping motor of the present invention has the following excellent effects because it is configured as described above. (1) When the same step angle is obtained, the magnetic pole width can be made wider than that of a two-phase PM type stepping motor, so that the torque is improved by 20% or more compared to a conventional motor having the same shape. (2) When the number of magnetic poles of the rotor is the same, a smaller step angle can be obtained as compared with a two-phase PM stepping motor. (3) The conventional two-phase PM type stepping motor requires at least four lead wires and eight drive circuit transistors, whereas the present invention requires three lead wires and six transistors. As a result, the driving circuit can be greatly simplified. (4) The current of the known three-phase PM type stepping motor has a phase angle of 60 °, while the current of the present invention has a phase angle of 120 °. Can also be used. (5) By changing the impedance of the winding, 3
It can also be used as a phase AC motor. (6) The multi-phase PM stepping motor of the present invention can be operated even in a delta connection. (7) Further, the polyphase PM stepping motor of the present invention
Then, the magnetization pitch P of the rotor is
Τs / 2, the stator magnetic pole pin
The switch is larger than the magnetized pitch of the rotor.
The magnetic resistance between the rotor and stator is smaller than
Therefore, a high torque can be obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a three-phase PM stepping motor according to the present invention.

FIG. 2 is an exploded perspective view of the three-phase PM stepping motor of the present invention.

FIG. 3 is a development view of a stator section and a rotor of the three-phase PM stepping motor of the present invention.

FIG. 4 is an explanatory diagram of a stator coil for simplifying and explaining the operation of the three-phase PM stepping motor of the present invention.

FIG. 5 is a circuit diagram of a stator coil drive circuit for simplifying and explaining the operation of the three-phase PM stepping motor of the present invention.

FIG. 6 is an excitation sequence diagram of a stator coil for simplifying and explaining the operation of the three-phase PM type stepping motor of the present invention.

FIG. 7 is a development view of pole teeth of a stator section and magnetic poles of a rotor for simply explaining the operation of the three-phase PM stepping motor of the present invention.

FIG. 8 is an explanatory diagram of a stator coil of the three-phase PM stepping motor of the present invention.

FIG. 9 is a stator coil drive circuit diagram of the three-phase PM stepping motor of the present invention.

FIG. 10 is an excitation sequence diagram of a stator coil of the three-phase PM stepping motor of the present invention.

FIG. 11 is a development view of pole teeth of a stator portion and magnetic poles of a rotor for simply describing the operation of the three-phase PM stepping motor of the present invention.

FIG. 12 is a table showing the relationship between the number of magnetic poles (P) of the rotor, the magnetic pole pitch (τr), and the step angle (θs) of the rotor.

FIG. 13 is a vertical side view of a conventional single-phase PM stepping motor.

FIG. 14 is an exploded longitudinal side view of a stator portion of a conventional single-phase PM stepping motor.

FIG. 15 is a vertical side view of a conventional two-phase PM stepping motor.

[Explanation of symbols]

 1: rotor 3: stator 3a to 3c: stator section 4, 4a to 4c: stator coil 8a, 8b: comb-shaped pole teeth of the stator TR1 to TR18: transistor

Claims (4)

(57) [Claims] 1. A rotor comprising a cylindrical permanent magnet in which N and S poles are alternately magnetized on an outer peripheral surface, and a certain gap with respect to the N or S pole on the outer peripheral surface of the rotor. Consisting of opposed stators, the stators being axially
The three first to third stator portions superposed on each other
And each of the above-mentioned stator portions is provided with a stator coil.
And the other that sandwich the stator coil from both sides
Yoke elements and the stator core
Extending in the axial direction along the inner peripheral surface of the il
Formed by one and the other pole teeth of the comb teeth spaced apart from each other
And the pole tooth pitch of one and the other of
Τs, each of the stator portions has the other
Pole teeth have .tau.s / 2 shifted from one of the pole teeth, whereas, when the magnetization pitch angle of the permanent magnet is P, each respective one or the position of each other of the pole teeth in each stator portion 2P / A multi-phase PM type stepping motor characterized in that it is arranged to be shifted by three angles. 2. The stator coil housed in the three yoke elements is coupled to three terminals, and two or three of the three stator coils are driven by a drive circuit composed of six transistors. 2. The multi-phase PM stepping motor according to claim 1, wherein the motors are simultaneously driven in a bipolar manner. 3. A rotor made of a cylindrical permanent magnet having N and S poles alternately magnetized on an outer peripheral surface thereof, and a fixed gap with respect to the N or S pole on the outer peripheral surface of the rotor. Consisting of opposed stators, the stators being axially
(N is an odd number) of the first to n-th stages superimposed on
And each of the above-mentioned stator portions is
The coil and this stator coil are clamped from both sides
One and the other yoke elements and the
Each extending in the axial direction along the inner peripheral surface of the stator coil
One and other pole teeth in the form of a comb that are circumferentially spaced from each other
And one and the other poles of each of the stator portions.
When the tooth pitch is τs,
And the other pole tooth is shifted by τs / 2 from one pole tooth.
Ri, whereas, if the magnetization pitch angle of the permanent magnet is P, and characterized by being adapted to staggered each 2P / n angle of each one or the position of each other of the pole teeth in each stator section PM type stepping motor. 4. The multi-phase PM stepping motor according to claim 1, wherein the rotor has a hybrid structure.