JPH0523756U - DC motor - Google Patents

Abstract

(57) [Summary] [Objective] To provide a DC motor aiming at reduction of cogging, load current, noise, and vibration. [Structure] In a permanent magnet field type DC motor, the width of the tip of the armature core that forms the slot opening is made alternately long and short in the circumferential direction, so that the slot opening is arranged on the shaft. In contrast, it is configured to be asymmetric.
Note that the number of slots is selected to be N = 2n + 4 (where n is a positive integer), and the winding pitch is selected from 1 to (N / 4 + 2) for a 4-pole motor (fractions below the decimal point are discarded). ), And 1-N / 2 for a 2-pole motor
(However, N = 4n + 2, n is a positive integer) or 1- (N
/ 2-1) (however, N = 4n + 4, n is a positive integer).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a DC motor that aims to reduce cogging, load current, noise, and vibration.

[0002]

[Prior Art]

 FIG. 2 is a block diagram of a conventional example. In the figure, reference numeral 5 is an armature core having 12 slots formed therein, and its slots 1 and slot openings 2 are symmetrically arranged with respect to the shaft 3 at a pitch of 30 °. The magnetic poles 4a to 4d of the permanent magnet on the stator side are also arranged symmetrically with respect to the shaft 3. 7 is an armature coil. The iron portion 5a at the tip of the iron core 5 facing the magnetic poles 4a to 4d and the slot opening 2 rotate to pass through the magnetic poles 4a to 4d mutually. At this time, the restraint portion where the iron portion at the tip of the iron core 5 is attracted to the opposing magnetic pole and the portion of the gap of the slot opening 2 which is opened by the roller alternate, and both of the stator and the rotor. Since all parts are symmetrical with respect to the shaft 3, the suction force and the opening timing overlap at a plurality of points, and the force at the time of change increases. In this way, pulsating torque occurs when suction → open, or vice versa, and the smaller the pulsation level, the better. In the case of a stepping motor, this torque is called the daytent torque.

[0003]

[Problems to be solved by the device]

 By the way, since motors for which all parts are symmetrical with respect to the shaft are for automobiles, mass productivity is important, so the windings are double wound by automatic winding. Therefore, the number of slots is even. In the case of the conventional example, the field pole of 4 poles and the armature having 12 slots face each other, and the air gap is maintained at 0.5 mm, for example. Since the tip of the armature core rotates by repeating the iron part and the slot opening, the magnetic flux changes at the magnetic pole ends 12 times / revolutions. In this case, 12 rotations / revolution is generated four times due to the symmetrical core shape with respect to the shaft, and the level of cogging torque becomes considerably large. It should be noted that even if the number of slots is changed from 12 to 14, two locations overlap. Thus, in the conventional permanent magnet field type DC motor, there is a problem in that as the cogging torque level increases, the mechanical loss increases and the no-load current also increases, causing pulsation in rotation, torque, and current. It was Therefore, in order to improve this point, the following technologies have been proposed. The slot is skewed. Increase the number of slots. Increase the gap. The inner and outer diameter centers of the magnetic pole shape are eccentric, and the gap is widened toward the tip. Use odd slots. The magnetized or shaped material is determined so that the magnetic flux distribution has a sinusoidal shape. However, the characteristics of these improved technologies deteriorate, while the characteristics of these improved technologies are not suitable for mass production. An object of the present invention is to provide a DC motor that solves the above-mentioned problems (problems) of conventional ones.

[0004]

[Means for Solving the Problems]

 In a permanent magnet field type DC motor, the width of the tip of the armature core that forms the slot opening is made longer and shorter alternately in the circumferential direction, so that the slot opening is arranged with respect to the shaft. The present invention relates to a DC motor configured to be asymmetric. In this case, the number of slots should be selected as N = 2n + 4 (where n is a positive integer). The selection of the winding pitch is 1 to (N / 4 + 2) for a 4-pole motor (however, the fractional part is rounded down), and 1-N / 2 (for N poles). = 4n + 2, n is a positive integer) or 1 to (N / 2-1) (where N = 4n + 4, n is a positive integer).

[0005]

[Operation] In the present invention, since the slot openings are combined so as to be asymmetric with respect to the shaft, it is possible to minimize the number of magnetic flux changes that have been simultaneously overlapped at a plurality of places. This also reduces the level of cogging torque.

[0006]

【Example】

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in FIG. In FIG. 1, the same reference numerals as those in FIG. 2 are used for the components corresponding to those of the conventional one. In the case of the present embodiment, the structure is an armature having four magnetic poles 4a to 4d of permanent magnets and fourteen slots. By the way, in the present invention, as shown in the figure, the widths of the armature cores 6a, 6b, 6c, 6d, ... Forming the slot openings are alternately arranged in the circumferential direction as shown in FIG. It is characterized in that the slot openings are arranged asymmetrically with respect to the shaft by forming them so as to satisfy _{1 to} L ₂ (L ₁ > L ₂ ). With such a configuration, the magnetic flux change that has been overlapped at a plurality of places at the same time becomes a minimum number of one place. In this case, the number of slots N may be set as follows. That is, N = 2n + 4 (where n is a positive integer). Basically, the number of slots may be an even number, but if the number of slots is 2 or 4, the polar arc degree of the field poles 4a to 4b of the permanent magnet and the slot tip widths L _{1 to} L ₂ are selected. It is excluded because there is no effective combination in. As a result, the winding pitch is selected as follows. For a 4-pole motor, 1 to (N / 4 + 2) (however, the numbers after the decimal point are rounded down). The rationale for this formula is that the angle of the winding pitch for mechanical winding is constant. For example, when the number of slots N = 14, the pitch is 1 to 5 and the angle is 102.86 °. In the case of a 2-pole motor, 1 to N / 2 (where N = 4n + 2 and n are positive integers) to 1 (N / 2-1) (where N = 4n + 4 and n are positive integers). This mathematical formula is determined in consideration of the fact that the feeding from one winding to the next is performed by repeating the large and small angles corresponding to L ₂ (large) and L ₁ (small). The machine index is a combination of large and small.

[0007]

[Effect of the device]

 As described above, according to the present invention, there are 14 places / revolutions at which cogging torque occurs, but since all these places are single shots (they do not overlap at the same time), the cogging torque The level becomes smaller and has the following excellent effects. Since the number of slots is even, double winding is possible and suitable for mass production. Since there is no skew, current winding machines can be used. This also reduces the pulsation of rotation, torque and current. (Approximately 1/4) Mechanical loss decreases, so no-load current can be reduced. Since the high frequency component corresponding to the rotation frequency is reduced, the noise level is lowered. Vibration is reduced. The iron core's receiving area is the same as the area covered by the magnetic poles, and the air gap remains unchanged, so the characteristics can be maintained.

[Brief description of drawings]

FIG. 1 is a front view showing the configuration of an embodiment of the present invention.

FIG. 2 is a front view showing a configuration of a conventional example.

[Explanation of symbols]

 1: Slot part 2: Slot opening part 3: Shaft 4a-4d: Magnetic pole 6: Armature iron core 6a-6d: Tip part (iron part) of the iron core

Claims (3)

[Scope of utility model registration request] 1. A permanent magnet field type DC electric motor,
The armature core that forms the slot opening is configured such that the width of the tip of the armature core is alternately long and short in the circumferential direction so that the slot opening is arranged asymmetrically with respect to the shaft. DC motor to do. 2. The DC motor according to claim 1, wherein the number of slots is selected to be N = 2n + 4 (where n is a positive integer). 3. The selection of the winding pitch is 1 to (N / 4 + 2) (round down to the decimal point) in the case of a 4-pole motor, and 1 to N / 2 in the case of a 2-pole motor (however, N =
4n + 2, n is a positive integer) or 1- (N / 2-1)
The DC motor according to claim 1 or 2, wherein (N = 4n + 4, n is a positive integer).