JPH04140046A - Dc motor - Google Patents

Abstract

PURPOSE:To improve assembling workability by arranging a rotor between U-shaped split frames having identical profile and size and simply holding the rotor, at the opposite ends thereof, between the split frames. CONSTITUTION:A rotor 40 is arranged between U-shaped split frames 21b, 21b having identical profile and size and the rotor 40 is held, at the opposite ends thereof, between the split frames 21, 21 thus assembling the rotor 40 into the frame 20. A magnet 30 is then bonded to the arched surface 22 of an intermediate wall 21a with the split frames 21, 21 being separated thus arranging the magnet 30 concentrically with the rotor 40. Consequently, the gap between the magnet 30 and the rotor 40 is made uniform entirely. Furthermore, since the arched surfaces 21d, 21d are formed, the outer end face 27a provides an oval end wall 27 between the opposing walls 21b, 21b and since a spigot part 29 is formed between true opposing wants 21b, 21b, high dimensional accuracy is not required for the split frame 21.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a DC motor having a frame (yoke) with open sides.

(Prior Art) Conventionally, motors (DC motors) used in electric razors and other small electric products, etc., are shown in Fig. 4, for example.
There is something like the one shown in Figure 5.

This motor consists of a frame l that is cylindrical (cup-shaped) with a bottom and has an oval cross-sectional shape as shown in FIG.
A magnet 2. is fixed to the arcuate inner surface 1a, lb of the magnet 2.
3, a lid 4 that closes the open end of the frame 1, and a rotor 5 rotatably disposed within the frame 1. The rotor 5 is rotatably held by the bottom wall 1c of the frame 1 and the lid 3. The motor also includes a commutator 6 provided on the rotor 5 and a brush 7 held by the lid 3 and in elastic contact with the commutator 6. The frame 1 is made of a magnetically permeable material, and the flat side wall 1d of the frame 1 is made of a magnetically permeable material.

A magnetic path between the magnets 2 and 3 is formed at 1d.

It is desirable that motors used in such small electric products be as small as possible and have as high torque as possible.

However, when a magnetic path is formed on the flat side walls 1d and ld,
Magnetic poles are also formed in the portions of the flat side walls 1d, ld facing the rotor 5, and the magnetic force generated from these magnetic poles acts in a direction to prevent the rotor 5 from rotating. As a result, the magnetic force of the magnets 2 and 3 cannot be effectively used to generate torque of the motor.

In order to improve the torque and downsize the motor, the flat side walls 1d and ld of the frame 1 may be opened.

By the way, the cup-shaped frame described above can be easily obtained by deep drawing a soft iron plate.

However, it is difficult to manufacture a frame l with open flat side walls 1d and ld by drawing or the like.

Therefore, conventionally, when manufacturing a motor with open sides, a frame lO as shown in FIGS. 6 and 7 has been used from the viewpoint of ease of processing.

This frame 10 includes a U-shaped plate 11 formed by bending a flat plate made of a magnetically conductive material into a U-shape, and a U-shaped plate 11 made of a magnetically conductive material that fixes the free end of this double-shaped plate 11. It is formed from an end plate 12.

This U-shaped plate 11 is formed into a U-shape from opposing walls 11a and llb and a continuous wall lie between the opposing walls 11a and flb. And this opposing wall 11a, ll
Magnets 13 and 14 are fixed to the opposite surfaces of b, and the rotor 15 disposed between the magnets 13 and 14
It is rotatably held by the continuous wall, and the continuous Jlill
The brushes 16.16 held by the rotor 16 are in elastic contact with the commutator 17 of the rotor 15.

(Problem to be Solved by the Invention) By the way, in the motor as shown in FIG. There was a problem in that it was not easy to do so, and it took time and effort to assemble the rotor 5 and brush 7.

Furthermore, a gap 18 is formed between the rotor 15 and the magnets 13, 14, but it is desirable that this gap 18 is formed uniformly because it has a large effect on the output torque of the motor.

However, although the frame 1o of the motor shown in FIG. 6 is easy to process, since the U-shaped plate 11 of the frame O is made of a thin iron plate, the U-shaped plate 111 is easily deformed. , it was difficult to form the gap 1B uniformly in the axial direction of the rotor 15.

Moreover, the magnets 13 and 14 are located on the flat opposing wall 11a.

Since it was adhered to the opposite surface of flb, the opposite wall 11a.

When fixing with adhesive to 11b, it tends to shift from side to side in Fig. 7,
It is also difficult to form the gap 18 uniformly in the rotational direction of the rotor 15.

Therefore, the first object of the second invention is to provide a DC motor that is easy to assemble.

A second object of the present invention is to provide a DC electric IjjJ machine that can easily and uniformly form the gap between the rotor and the magnet.

Furthermore, a third object of the present invention is to provide a DC motor that can be assembled with dimensional accuracy through simple machining.

(4) Means for Solving the Problems) Based on the first object, the present invention provides a two-character shape formed by an intermediate wall and opposing walls connected at right angles in the same direction at both ends of the intermediate wall. By preparing a pair of split frames of the same shape and size and aligning the end faces of both opposing walls of said one split frame with the end faces of both opposing walls of said other split frame, A frame having a rectangular shape and opening laterally is formed, and magnets are fixed to opposing surfaces of the intermediate wall, and each end of the rotor shaft of the rotor disposed between the magnets is connected between the matched opposing walls. The present invention is characterized by a DC motor that is held rotatably.

Further, in order to achieve the second object, the present invention provides that a portion of the intermediate wall facing the rotor is formed with an arcuate surface concentric with the rotor, and the arcuate surface shapes the divided frame. The present invention is characterized in that a DC motor is formed on the intermediate wall.

Furthermore, in order to achieve the third object, the present invention provides an arcuate surface on a surface opposite to the mating surfaces of the opposing walls that are aligned with each other, so that an outer end surface is formed between the opposing walls. An oval-shaped end wall is formed, and a spigot part that is coaxial with the shaft insertion hole and open to the end surface of the end wall and whose shortest dimension from the center of the arcuate surface is accurately set. The end portion of the rotor shaft formed in the opposing hearsay and inserted into the shaft insertion hole is rotatably held by a bearing engaged with the spigot part, and the combined opposing walls are attached to the outer circumferential surface of the end wall. It is characterized by a DC motor fixed with a fitted cap.

(Function) According to such a configuration, the rotor is disposed between the split frames having the same shape and size, and by simply holding both ends of the rotor between the split frames, the rotor can be rotated. is assembled into the frame: becomes J.

In addition, the magnet can be used with the split frame separated.
By gluing it to the arcuate surface of the intermediate wall, it becomes concentric with the rotor. This makes the gap between the magnet and the rotor uniform throughout.

Further, by forming an arcuate surface on the surface opposite to the mating surface of the opposing walls that are aligned with each other, an end wall having an oval outer end surface is formed between the opposing walls, and the shaft insertion hole and the Since a spigot part is formed between the opposing walls, which is coaxial with the shaft insertion hole and open to the end surface of the end wall, and whose shortest dimension from the center of the arcuate surface is accurately set, the dimensions of the split frame are There is no need to increase overall accuracy. As a result, there is no need to increase the overall machining accuracy of the mold for machining the split frame, so machining of the mold becomes easier.

(Example) Hereinafter, an example of the present invention will be described based on FIGS. 1 to 3.

FIG. 1 is a sectional view of an assembled DC motor according to the present invention, and FIG. 2 is an exploded perspective view of the DC motor shown in FIG.

This DC motor has a rectangular frame 20 that opens laterally.
and a magnet 30.3 attached to the frame 20.
0 and the rotor 40 disposed between the magnets 30 and 30.
and a rotor shaft 41 provided integrally with the rotor 40. The magnet 3o has a cross-sectional shape or an arc shape (see FIG. 3).

The DC motor also includes a bearing 50, 50 that rotatably supports the rotor shaft 41 on the frame 2°, a commutator 42 that is integrally provided with the rotor shaft 41, and a brush that is attached to the frame 20 and comes in elastic contact with the commutator 42. 43
has.

The frame 2o described above is a pair of divided frames 21 formed of a magnetically permeable material such as iron and having the same shape and size.
．． It has 21. This split frame 21 is formed by sintering or precision casting.

In the case of sintering, the final divided frame 21 is obtained by press-forming iron powder with a mold and then firing the press-formed product. In the case of precision casting, the final split frame 21 is formed by injecting molten iron into a cavity in the mold and cooling it.

The divided frame 21 is formed into a mouth shape by an intermediate wall 21m and opposing walls 21b, 21b which are connected to both ends of the intermediate wall 21a at right angles in the same direction.

A portion of the intermediate wall 21a facing the rotor 4o is provided with a rotor 4
0 (see FIG. 3), the arcuate surface 22 is formed on the intermediate wall 21a when the split frame 21 is molded as described above.

The outer peripheral surface of the magnet 3o is adhesively fixed to the second arcuate surface 22. This bonding can be carried out with the split frames 21.21 separated.

Further, as shown in FIG. 2, in the end face 21c of each opposing wall 21b, semi-cylindrical recesses 23 and 24 of different sizes and diameters are coaxially formed, and the recesses 23 and 24 are formed in the portions sandwiching the recesses 23. A positioning hole 25 and a positioning protrusion 26 are formed. This recess 23 is formed to have a smaller diameter than the recess 24 and is located on the magnet 30 side.

And one split frame 210 facing each other! ! 21b.

The end faces 21c and 21c of 21b are connected to the other split frame 2.
Both opposing walls 21b of 1, end surfaces 21c of 21b, 21c
By aligning them with each other, the positioning protrusion 26 of one end surface 21c to be matched is aligned with the other end surface 2 to be matched.
It will be fitted into the positioning hole 25 of 1c. As a result, a frame 2o having a substantially rectangular side surface and open to the side is formed, and the opposing walls 21b and 21 are joined together.
An end wall 27 of the frame 20 is formed by b.

Moreover, the end surfaces 21c, 21c of the opposing faces 921b, 21b, which are aligned with each other, have an arcuate surface 21d on the opposite side.
, 21d are formed, and this opposing l! ! 21d,
The outer end surface 27a of the end M27 formed by 21d is formed into an oval shape. A recess 21e is formed in the center of this arcuate surface 21d.

Also, by combining the divided frames 21 and 21,
Recess 23 on one split frame and split frame 2 on the other
A shaft insertion hole 28 is formed by the recess 23 of one split frame, and a spigot part 29 that opens on the outer end surface 27m of the end wall 27 is formed by the recess 24 of one split frame and the recess 24 of the other split frame 21. be done. The second shaft insertion hole 2B and the spigot part 29 are provided coaxially, from a point A in the center of the arcuate surface 21d to a point B in the spigot part 29, that is, the recess 2.1.
The shortest dimension and the dimensions from end surface 2]c to points A and B and the arcuate surface 22 are set accurately.

Then, insert the end of the rotor shaft 41 into the shaft insertion hole 28,
This end portion is rotatably held by a bearing 50° 50 engaged with the spigot portion 29. In addition, the opposing walls 21b, 21b are fixed by a cap 51 fitted to the outer peripheral surface of the end wall 27. Note that the cap 51 has the central end 51b of the arcuate portion 51m placed in the recess 21e as shown in FIG.
It is fixed to the split frame 21°21 by caulking.

Next, the operation of such a configuration will be explained.

According to such a configuration, the rotor 40 is disposed between the U-shaped split frames 21b, 21b having the same shape and size, and both ends of the rotor 40 are simply held between the split frames 21. By this, the rotor 40 is connected to the frame 20.
It will be assembled into.

Further, the magnet 30 becomes concentric with the rotor 40 by adhering it to the arcuate surface 22 at the middle 1421m with the divided frames 21.21 separated. Thereby, the gap between the magnet 30 and the rotor 40 becomes uniform throughout.

Further, by forming arcuate surfaces 21d, 21d on the mating surfaces of the facing walls 21b, 21b, that is, the surfaces opposite to the end surfaces 21c, 21c, the outer end surface 27a is formed into an oval shape between the facing walls 21b, 21b. Edge of shape M
27, and a shaft insertion hole 28 and a shaft insertion hole 28.
And the coaxial end! ! Since the spigot part 29, which is open to the outer end surface 27m of the split frame 27 and whose shortest dimension from the center of the arcuate surface 21d is accurately set, is formed between the opposing walls 21b, 21b, the dimensional accuracy of the split frame 2 is improved. There is no need to increase the overall height. As a result, there is no need to increase the overall machining accuracy of the mold for machining the split frame 21, so machining of the mold becomes easy.

(Effects of the Invention) According to such a configuration, the rotor is disposed between the U-shaped divided frames having the same shape and size, and both ends of the rotor are simply held between the divided frames. , the rotor will be assembled to the frame. As a result, installation workability can be improved.

In addition, the magnet can be used with the split frame separated.
By gluing it to the arcuate surface of the intermediate wall, it becomes concentric with the rotor. This makes the gap between the magnet and the rotor uniform throughout.

Further, by forming an arcuate surface on the surface opposite to the mating surface of the opposing walls that are aligned with each other, an end wall having an oval outer end surface is formed between the opposing walls, and the shaft insertion hole and the Since a spigot part is formed between the opposing walls, which is coaxial with the shaft insertion hole and open to the end surface of the end wall, and whose shortest dimension from the center of the arcuate surface is accurately set, the dimensions of the split frame are There is no need to increase overall accuracy. As a result, there is no need to increase the overall machining accuracy of the mold for machining the split frame, so machining of the mold becomes easier. As a result, assembly dimensional accuracy can be achieved with simple machining.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a DC motor showing an embodiment of the present invention. FIG. 2 is an exploded perspective view of the DC motor with the brush shown in FIG. 1 omitted. 3 is a sectional view orthogonal to the rotor axis of the DC motor of FIG. 1. FIG. FIG. 4 is a half-sectional view showing an example of a conventional DC motor. FIG. 5 is a cross-sectional view of the DC motor shown in FIG. 4. FIG. 6 is a half-sectional view showing another example of a conventional DC motor. FIG. 7 is a cross-sectional view of the DC motor shown in FIG. 6. 20... Frame 21... Divided frame 21a... Intermediate wall 21b... Opposing wall 21c... End surface 21d... Arc-shaped surface 22... Arc-shaped surface 28... Shaft insertion hole 29 ... Pilot section 30 ... Magnet 40 Rotor 41 ... Rotor shaft 50 ... Bearing

Claims (3)

[Claims] (1) Prepare a pair of split frames of the same shape and size formed in a U-shape from an intermediate wall and opposing walls connected at right angles in the same direction to both ends of the intermediate wall, By aligning the end faces of both opposing walls of the one split frame with the end faces of both opposing walls of the other split frame,
A frame having a rectangular side surface and open to the sides is formed, and a magnet is fixed to the opposing surface of the intermediate wall, and each end of the rotor shaft of the rotor disposed between the magnets is connected to the matched opposing wall. A direct current motor characterized by being rotatably held between the parts. (2) An arcuate surface concentric with the rotor is formed in a portion of the intermediate wall facing the rotor, and the arcuate surface is formed on the intermediate wall when molding the split frame. The DC motor according to claim 1. (3) By forming an arcuate surface on the surface opposite to the mating surface of the opposing walls that are aligned with each other, an end wall having an oval outer end surface is formed between the opposing walls, and a shaft insertion hole is formed. and a spigot part coaxial with the shaft insertion hole, open to the end surface of the end wall, and having an accurately set shortest dimension from the center of the arcuate surface, is formed between the opposing walls, and in the shaft insertion hole. The inserted end of the rotor shaft is rotatably held by a bearing engaged with the spigot part, and the combined opposing walls are fixed with a cap fitted to the outer peripheral surface of the end wall. The DC motor according to claim 1.