JPS602065A - Stepping motor - Google Patents

Abstract

PURPOSE:To strongly set a rotor to inactive state even not energized by dividing a stator core into the regular first and second rows opposite to the rotor having a cylindrical permanent magnet alternately magnetized at N-poles and S-poles on the outer periphery. CONSTITUTION:A rotor 5 (shown in a developed view, hereinafter referred to similarly) having a permanent magnet magnetized alternately at N-poles and S- poles around a rotational shaft is formed. A stator core opposed to the rotor 5 is energized by a coil to be formed of the first arrays 21, 22, 21, 22 of the stator cores arranged regularly and of the second arays 23, 24, 23, 24... arranged irregularly. In this manner, strong and weak detent torques arise, but when the coil is not energized, the core is stopped at the position where the strongest detent torque (coercive force) is produced as shown, the core is strongly in the inactive state, thereby saving the power consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a high detent torque P that is capable of holding the stopping position of the shaft at a constant position with high precision and strongly.
'This relates to an M-type step motor.

The conventionally known P'M type snap step motor has a structure as shown in FIG. 1 in order to convert the rotary motion of the rotor into linear motion of the shaft using a screw or the like.

In FIG. 1, the reference numeral ``■'' indicates a first housing in the form of a tip, and the numeral 2 indicates a second housing shaped like a disc. Both of them form the outer shell of the motor, which are fixed to each other by screws 3. A rotor 4 has a permanent magnet 5 on its outer diameter, an internal thread 6 on its inner diameter, and stoppers 7 for restricting the rotation of the rotor 4 at both ends. A male screw 9 provided on a shaft 8 is engaged with the female thread 6.

Further, stopper bins 10.11 are provided on the shaft 8 at intervals, and the rotational force of the rotor 4 is transmitted to the shaft 8 by the stopper 7 of the rotor 4 meshing with the stopper bins 10.11. Further, the movable length of the shaft 8 is from a position where the stopper 7 of the rotor and the stopper bin 10 engage with each other to a position where the stopper 7 provided on the rotor 4 and the stopper bin 11 of the shaft 8 engage with each other.

Bearings 12, 12' are provided at both ends of the rotor 4.
They are fixed to the housing 1 and the second housing 2, respectively. The shaft 8 is held in a sintered oil-impregnated bearing 13,13' which is fixed to each housing 1.2. Rotor 4
Stator cores 15 and 15' serving as stator poles are provided outside the gap 14 and are fixed to the first housing 1.

The excitation coils 17 and 17' of the stator, which are insulated by the bobbin 16, are wound on the inside thereof, and are wired as shown in FIG. Since the rotor 4 rotates by turning ON and OFF the current flowing through the exciting coils 17, 17' in a predetermined order, the shaft 8 performs forward or backward linear motion.

In the case of two-phase excitation, the excitation is performed at the timing shown in FIG. 4, and the rotational speed of the rotor 4 is determined by the time interval t of the timing.

Also, the excitation of the excitation coils 17 and 17' is during rotation.

It is common for the rotor 4 to twist at all times regardless of when it is stopped, and in this case, the holding torque of the rotor 4 when it is stopped is strong, but the transistors TRI~T
R4 must be able to withstand continuous energization and be resistant to destruction due to self-heating, which necessitates the use of a large transistor. Furthermore, even when stopped, the excitation coil 17
．． 17' is energized, so it consumes extra power.

For this reason, the inventor adopted a method in which the excitation coils 17, 17' are excited only during rotation, and the excitation of all excitation coils 17, 17' is also stopped when the rotation is stopped. As a result, small and inexpensive transistors TR1-TR4 can be used, and the heat sinks of the transistors can also be made small, furthermore, no extra power is consumed.

However, when such a step motor is used, for example, in a valve that controls the amount of air taken into an automobile engine, a drawback arises in that the rotor rotates due to engine vibration when the step motor is stopped.

When the excitation is stopped, the stator core 15.15'
The N and S poles of the rotor disappear and it becomes a mere ferromagnetic material, so that only the attraction force (detent torque) of the magnetic material is generated by the permanent magnet 5 of the rotor 4. However, in conventional motors, the stator core 15
．． 15' is N of the permanent magnet 5 as shown in FIG.

The position W (spacing W) of the teeth with the S pole serving as the pole of the stator core was uniform, and the above-mentioned delay torque was relatively small.

The present invention was made in view of the above-mentioned problems, and it does not excite the excitation coil (but by intentionally shifting the position W (spacing) of the teeth of the stator core in order to strengthen the holding force of the rotor. The object of the present invention is to provide a PM type step motor that has a strong holding force (detent torque) between the rotor and stator core when the excitation coil is deenergized.

An embodiment of the present invention will be described below.

What is shown in FIG. 1 is, for example, a 24-step/rotation motor, which is illustrated to clarify the gist of the present invention.
In the stator core 15, 15' of the motor, the distance N (spacing) between the teeth of the stator core is as shown in FIG.
For a constant interval W, the teeth 21.22 of the upper row are
The central axis of is shifted to the left by θ. On the other hand, @ in the bottom row
23 and 24 indicate that the central axis of the tooth 24 is shifted to the right by θ.

This relationship is clear when comparing FIGS. 5 and 6.

At this time, as is well known, due to the structure of the step motor, the stator core teeth 21 and 23, and 22 and 24 can be constructed as the same part, so for example, the stator core teeth 2
If the positions of the teeth 1 and 23 are not shifted, but the center axes of the teeth 22 and 24 of the stator core are shifted by θ, it is possible to obtain the structure of the present invention after assembly. Next, the total number of teeth is the same as the number of N5NS poles of the permanent magnet 5, as in the conventional motor, and the stay cores 15, 15' of each row are provided.

Further, the θ at which the tooth position is smoothed may be arbitrarily set to a value between 0 (zero) <θ<W to ensure performance. Furthermore, the direction in which θ is taken can be either to the right or to the left with respect to the central axis, that is, it is possible to have the same configuration either way.

With this configuration, since the positions of the teeth of the stator core 15, 15' are shifted by θ, when the rotation operation is performed, the step angle is alternately set to 1, 2, 1, 2, 3, 3, 4, 5, 4, 5, 4, 5, 6, 7, 10, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 15, 18, and 18, respectively.

On the other hand, when the stator core 15 is not energized when stopped,
．． The teeth 15' become mere iron claws, and a magnetic circuit including the stator core (15, !5') is established due to the magnetomotive force of the permanent magnet 5, and a detined dockle is generated in the rotor 4. Since the number of teeth on the stator core 15.15' is twice the number of poles, f+2 teeth on the stator core 15.15' are attracted to one pole of the permanent magnet 5.

Then, as shown in Fig. 186, by shifting by θ, the more closely spaced teeth ±22.24 and the permanent magnet 111 (N or S may be used) are strongly balanced. In other words, while the magnetic coupling is stronger in Figure 6 than in Figure 5, when the poles of the permanent magnet 5 attract each other at a distance of ±23°21 as shown in Figure 7, The attractive force becomes small, and the permanent magnet 5 of the rotor 4 rotates (it is not determined in which direction it rotates) to the position of the large attractive force shown in FIG. 6.

Therefore, the final excitation phase before the de-energization is set to the permanent magnet 5.
The rotor 4 can be reliably stopped at a position where the detent torque is large by setting the excitation phase to a position as shown in Fig. 6, where the poles of the stator core are strongly balanced with the teeth of the stator core, or a position adjacent to this position. can.

In the above embodiment, a linear operation type motor that converts the rotation of the rotor 4 into linear motion of the shaft 8 was explained, but a rotary type motor is also used.
The present invention can also be applied to a case where the rotation movement is made only at a certain angle and then stopped.

Moreover, it goes without saying that the number of steps can be set arbitrarily.

In this way, the above embodiment has a rotor 4 having a cylindrical permanent magnet 5, and a gap 1 through which a constant magnetic flux passes through the N4111 or S poles alternately magnetized on the outer peripheral surface of the rotor 4.
A stator core 15.15' is provided via 4.

The teeth of the stator core 15, 15' are arranged in two rows, a first row and a second row, around the rotor 4, as shown in FIGS. 5 to 7. That is, the first row of teeth is 21°22 in Figure 6, and the second row is 23°.
．． It is 24.

Further, in FIGS. 6 and 7 according to the present invention, the teeth in each row are arranged at non-uniform intervals, whereas in the conventional tooth shown in FIG. 5, they are arranged at equal intervals (2W). Therefore, in the present invention, the first portions (the portions of teeth 22 and 24 in FIG. 6) arranged in a substantially straight line along the axial direction of the shaft 8, and the first portions arranged in a substantially straight line along the axial direction of the shaft 8, and the first portions arranged in each row at right angles to the axial direction. The second part (6th part) where the teeth are arranged apart apart
The teeth 21 and 23 in the figure) are formed.

Therefore, when the first portions 22 and 24 overlap one pole of the permanent magnet 5, a strong magnetic attraction force (detent torque) will act between them. This state is shown in FIG. 6. In FIG. 6, Sfi is induced in the teeth 22.24 that overlap the N poles of the permanent magnet 5 in a substantially straight line (at this time, the excitation coil 17.17' is deenergized). ), N pole and tooth 22.24
are strongly attracted to each other, and the Deten 1 torque becomes larger than in the case shown in Fig. 5.

On the other hand, when the first portion 2'2.24 and the magnetic poles of the permanent magnet 5 do not overlap well as shown in Fig. 7, the holding force (detent torque) is actually smaller than that in Fig. 5. .

In other words, according to the present invention, the holding force (detent torque) is formed into dense and dense portions, and the holding force in the dense portions is strengthened.

Therefore, if you use this strengthened holding power in the position,
A step motor with strong holding force can be used.

As described above, the present invention has the effect that the retention force (detent torque) of the rotor when the excitation coil is deenergized can be achieved simply by changing the arrangement of the teeth of the stay core. This has the effect that a device using this motor can be more strongly brought into a stationary state when not energized.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view showing an example of a conventional step motor and a step motor to which the present invention can be applied, FIGS. 2 and 3 are schematic wiring diagrams of the excitation circuit of the motor, and FIG. 4 is a diagram of the excitation coil of the motor. FIG. 5 is a schematic diagram showing the tooth arrangement of a conventional motor, and FIGS. 6 and 7 are schematic diagrams showing the tooth arrangement in an embodiment of the motor of the present invention. 4... Rotor, 8... Shaft, 12.12'... Bearing, 1゜2... Housing, 15.15'... Stator core, 17.17'... Excitation coil, 21, 22,
23゜24...Stator core teeth. Representative Patent Attorney Takashi Okabe Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] A rotor having a cylindrical permanent magnet formed by alternately magnetizing N@ and S poles on its outer circumferential surface, a housing that rotatably holds the rotor therein, and a housing for rotatably holding the rotor therein; a stator core provided between an inner peripheral wall and an outer periphery of the rotor and disposed opposite to the N pole or the S pole of the outer peripheral surface of the rotor through a certain gap; an excitation coil that magnetizes teeth of a stator core to drive the rotor stepwise; and the teeth of the stator core are divided into two rows, a first row and a second row, around the rotor to drive the rotor. The teeth constituting each row of the stator core are arranged in a ring shape at non-uniform intervals around the rotor, and are arranged in a ring shape with respect to the N pole or the S pole of the outer circumferential surface of the rotor. a first portion in which the first row of teeth and the second row of teeth are arranged substantially linearly along the axial direction of the shaft; a second portion in which the teeth of each row are spaced apart is formed on the teeth of the stator core so that in the rotational position of the rotor relative to the stator core, the excitation coil is in an unexcited state; The step motor may be characterized in that portions where the rotor and the stator core have a strong magnetic coupling force and portions where the magnetic coupling force is weak are alternately formed.