JPH0147115B2 - - Google Patents

Description

[Detailed Description of the Invention] This invention provides a stepping motor, etc.
The present invention relates to field poles for motors that aim to improve startability by reducing inertial vibrations and bearing noise due to the cocking effect generated between the rotor and field poles.

Conventionally, stepping motors shown in the exploded perspective view of FIG. 1 and the assembled view of FIG. 2 have been used.

In the figure, 1 is a rotor consisting of a cylindrical multi-pole permanent magnet 2 and a rotating shaft 3, and 4 and 5 are:
A pair of left and right coil bobbins with balanced coil winding.

Of the coil bobbins 4 and 5, the coil bobbin 4 is held between both sides by a stator 6 that also serves as a casing and has a large number of identically shaped magnetic pole pieces 6a, and a stator 7 that has the same number and identically shaped magnetic pole pieces 7a, and is held between the other coil bobbin 5. are respectively pole pieces 8
It is sandwiched from both sides by stators 8 and 9 having a and 9a, and each stator 6, 7, 8, 9
The rotating shaft 3 of the rotor 1 passes through the center of the bearing 10 of the stator 6, which also serves as a casing, and the lid 11.
It is rotatably supported by a bearing 11a.

In the configuration of the stepping motor, the same-shaped magnetic pole pieces 6a and 7a and 8a and 9a of each stator are positioned alternately facing each other without contacting each other, and the phase of each magnetic pole is adjusted between the left and right coil bobbins 4 and 5. It is positioned in a shifted position.

However, in the conventional stepping motor described above, the multi-pole field poles, which are comb-shaped magnetic pole pieces forming the stator, are as shown in FIG.
Square teeth and rectangular teeth are common, and their magnetic pole pieces face each other with a gap left, but no particular consideration is given to the size of that gap. In other words, the difference between the distance a between the base ends of the tooth profiles and the distance b between the tooth tips in the axial direction of the stator is increasing, and this difference in gap size appears as a change in magnetic force, which causes the occurrence of the cocking phenomenon. It is the cause. Therefore, residual torque increases, torque loss increases, efficiency decreases, vibrations and noise are caused, and bearing loss caused by the above causes shortened life.

This invention was made to solve the above-mentioned conventional drawbacks, and in order to eliminate the knocking phenomenon that occurs between the rotor and field poles in stepping motors, etc., the shape and arrangement of the comb-shaped magnetic pole pieces of the stator are taken into consideration. The present invention also provides field poles for a motor, characterized in that the gaps around the magnetic pole pieces of the stators that are alternately arranged facing each other are set to be equal in the axial direction.

First, the basic principle of this invention will be explained based on FIGS. 4 and 5. In other words, as shown in Fig. 4, the state in which there is no "knocking" phenomenon is when a cylindrical field pole magnetic iron plate S is placed coaxially with the rotor R of the cylindrical magnet, and the rotor R is rotated. In this case, there is no change in magnetic resistance, so no twitching occurs.

Further, even if the cylindrical magnetic iron plate S is cut into rounds at the center, or even if the slices are slightly moved in the axial direction while remaining coaxial, there is no change in magnetic resistance and no sagging occurs.

Therefore, by changing the above-mentioned method of slicing, we can cut any shape on the circumference with the slit as the center line, such as a triangular wave or a sine wave as shown in Fig. 5.
Even if the cylindrical magnetic iron plates S and S' are moved a certain distance in the axial direction after cutting in the shape of a trapezoidal wave, no twitching will occur as described above.

In this case, the constant distance in the axial direction of the cylindrical magnetic iron plates S and S' means that the cylindrical magnetic iron plates S and S' are set at equal intervals at any point in the axial direction, and are meshed alternately.
Moreover, it is necessary that they have the same shape.

What is shown in FIG. 6 is an embodiment of the present invention constructed based on the above-mentioned basic principle, in which the comb-shaped stators 20 and 21 are shown in a developed view. The magnetic pole piece 20 of this stator 20, 21
a, 21a are formed into a trapezoidal shape and are meshed alternately with a gap therebetween, and the gap around the entire circumference of the magnetic pole pieces is set so that the distance d in the axial direction is equal at all points.

As mentioned above, if the gaps around the entire circumference of adjacent magnetic pole pieces are formed equally in the axial direction,
Since the field surface relative to the magnetic poles of the rotor is always constant regardless of the rotational position of the rotor, no twitching phenomenon occurs.

Note that the magnetic pole pieces 20 of the stators 20 and 21
The shapes of a and 21a are not limited to trapezoids, but may be any shape as long as the spacing in the axial direction can be made equal at all points; for example, shapes such as triangular waves and sine waves can be arbitrarily selected. .

As described above, according to the present invention, in a motor field pole in which a large number of magnetic pole pieces of the same shape and oriented in the axial direction are arranged alternately N and S at the same pitch in the circumferential direction, adjacent Since the gaps around the entire circumference of the matching magnetic pole pieces are formed to be equal in the axial direction, the field area relative to the rotor's magnetic poles is always constant regardless of the rotor's rotational position, and changes in reluctance are virtually constant. Since there is no minimum reluctance position like in conventional motors, there is a phenomenon in which the rotor is attracted to the minimum reluctance position and requires torque to escape from the starting position, i.e. Since no twitching phenomenon occurs, stable rotation can be obtained during motor operation.

Moreover, by eliminating the above-mentioned twitching phenomenon, inertial vibrations and bearing noise are also reduced, and there are other effects such as improvement in starting and stopping.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of the stepping motor, FIG. 2 is a partially sectional side view showing the assembled state, and FIG. 3 is an enlarged side view showing the arrangement of the magnetic pole pieces in FIG.
4 and 5 are perspective views of main parts of a motor for explaining the basic principle of the invention, and FIG. 6 is an exploded view of a stator showing an embodiment of the invention. 1... Rotor, 2... Cylindrical magnet, 3... Rotating shaft, 4, 5... Coil bobbin, 6, 7, 8, 9...
...Stator, 6a, 7a, 8a, 9a...Pole piece, 10...Bearing, 11...Lid, 11a...Bearing, R...Rotor, S, S'...Cylindrical iron plate for field,
20, 21... Stator, 20a, 21a... Magnetic pole piece.

Claims (1)

[Claims] 1. In a motor field pole in which a large number of magnetic pole pieces of the same shape oriented in the axial direction are arranged alternately N and S at the same pitch in the circumferential direction, the gap around the entire circumference between adjacent magnetic pole pieces is A field pole for a motor, characterized in that the field poles are formed to be equal across the field.