JP2577499B2 - DC motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DC motor having a frame (yoke) with an open side surface.

(Prior art) As a motor (DC motor) conventionally used for electric razors and other small electric products, for example,
FIG. 5 and FIG.

This motor has an oval frame 1 having a bottomed cylindrical shape (cup shape) and a cross-sectional shape as shown in FIG. 5, magnets 2 and 3 fixed to arc-shaped inner surfaces 1a and 1b of the frame 1, The frame 1 includes a lid 4 for closing an open end, and a rotor 5 rotatably disposed in the frame 1. This rotor 5
Is rotatably held by the bottom wall 1c of the frame 1 and the lid 3. The motor has a commutator 6 provided on the rotor 5 and a brush 7 held on the lid 3 and in elastic contact with the commutator 6. The frame 1 is made of a magnetic conductive material, and the flat side walls 1d, 1d
A magnetic path is formed between the magnets 2 and 3 at the same time.

It is desirable that the motor used in such a small electric appliance is as small as possible and has a large torque.

However, when a magnetic path is formed in the flat side walls 1d, 1d, magnetic poles are also formed in portions of the flat side walls 1d, 1d facing the rotor 5, and the magnetic force generated by the magnetic poles prevents the rotor 5 from rotating. Act on. As a result, the magnetic force of the magnets 2 and 3 cannot be effectively used for generating the torque of the motor.

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

By the way, the above-mentioned cup-shaped frame 1 can be easily obtained by deep drawing a plate made of soft iron.

However, it is difficult to manufacture the frame 1 in which the flat side walls 1d and 1d are open by drawing or the like.

Therefore, conventionally, when manufacturing a motor having an open side, a frame 10 as shown in FIGS. 6 and 7 has been used from the viewpoint of ease of processing.

The frame 10 has a U-shaped plate 11 formed by bending a flat plate made of a magnetic conductive material into a U-shape, and a U-shaped plate 11 made of a magnetic conductive material fixing a free end of the U-shaped plate 11. The end plate 12 is formed.

The U-shaped plate 11 includes opposing walls 11a and 11b and an opposing wall 1
It is formed in a U-shape from a continuous wall 11c between 1a and 11b. Magnets 13 and 14 are fixed to the opposing surfaces of the opposing walls 11a and 11b, and a rotor 15 disposed between the magnets 13 and 14 is provided.
Is rotatably held by the end plate 12 and the connecting wall 11c, and the connecting wall 11c
Brushes 16, 16 held by the rotor 15 are commutators 17 of the rotor 15.
I am in contact with

(Problems to be Solved by the Invention) In the motor as shown in FIG. 4, since the cup-shaped frame 1 has a small diameter and a small work space, the magnets 2 and 3 are inserted into the frame 1 and fixed. This is not easy, and there is a problem that the work of assembling the rotor 5 and the brush 7 is troublesome.

Further, a gap 18 is formed between the rotor 15 and the magnets 13 and 14. Since the gap 18 has a large effect on the output torque of the motor, it is desirable that the gap 18 be formed uniformly.

However, although the processing of the motor frame 10 shown in FIG. 6 is easy, since the U-shaped plate 11 of the frame 10 is made of a thin iron plate, the U-shaped plate 11 is easily deformed. It is difficult to form the gap 18 uniformly in the axial direction of the rotor 15.

Further, since the magnets 13 and 14 are adhered to the opposing surfaces of the flat opposing walls 11a and 11b, when the magnets 13 and 14 are adhered and fixed to the opposing walls 11a and 11b, they are easily shifted left and right in FIG.
It was also difficult to form them uniformly in 15 rotation directions.

Therefore, a first object of the present invention is to provide a DC motor having good workability in installation.

A second object of the present invention is to provide a DC motor capable of easily and uniformly forming a gap between a rotor and a magnet.

Further, a third object of the present invention is to provide a DC motor capable of assembling dimensional accuracy with simple processing.

(Means for Solving the Problems) Based on this first object, the present invention provides a U-shape comprising an intermediate wall and opposing walls provided at right angles to both ends of the intermediate wall in the same direction. A pair of divided frames having the same shape and the same size formed in the above is prepared, and the end faces of both opposed walls of the one divided frame are respectively matched with the end faces of both opposed walls of the other divided frame, so that the side faces are formed. A frame having a rectangular shape and opening to the side 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 disposed between the aligned opposing walls. The DC motor is rotatably held in the DC motor.

Further, in order to achieve a second object, according to the present invention, an arc-shaped surface concentric with the rotor is formed on a portion of the intermediate wall facing the rotor, and the arc-shaped surface molds the divided frame. In this case, a DC motor is formed on the intermediate wall.

Further, in order to achieve the third object, the present invention provides:
By forming an arc-shaped surface on the surface opposite to the mating surface of the opposing walls, the outer end surface forms an oval end wall between the opposing walls, and a shaft insertion hole and the shaft are formed. The spigot portion, which is coaxial with the insertion hole and is opened to the end face of the end wall and whose shortest dimension from the center of the arc-shaped surface is accurately set, is formed between the opposed walls, and is inserted into the shaft insertion hole. A DC motor in which an end of the rotor shaft is rotatably held by a bearing engaged with the spigot portion, and the combined opposing walls are fixed by a cap fitted to an outer peripheral surface of the end wall. I do.

(Operation) According to such a configuration, the rotor is disposed between the U-shaped divided frames of the same shape and size, and both ends of the rotor are simply sandwiched between the divided frames. It will be assembled to the frame.

Further, the magnet is concentric with the rotor by bonding the magnet to the arc-shaped surface of the intermediate wall in a state where the divided frame is separated. Thereby, the gap between the magnet and the rotor becomes uniform as a whole.

Further, by forming an arc-shaped surface on the surface opposite to the mating surface of the opposing walls that are mated with each other, an outer end surface forms an oval end wall between the opposing walls, and a shaft insertion hole and the shaft insertion hole. Since the spigot part which is coaxial with the shaft insertion hole and is open to the end face of the end wall and whose shortest dimension from the center of the arc-shaped surface is accurately set is formed between the opposed walls, the size of the divided frame is increased. There is no need to increase the accuracy as a whole. As a result, since it is not necessary to increase the processing accuracy of the mold for processing the divided frame as a whole, the processing of the mold is also facilitated.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a state in which a DC motor according to the present invention is assembled, 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 to the side.
And magnets 30, 30 attached to the frame 20,
A rotor 40 disposed between the magnets 30, 30;
Has a rotor shaft 41 provided integrally therewith. The magnet 30 has an arc-shaped cross section (see FIG. 3).

Further, the DC motor includes bearings 50 and 50 that rotatably support the rotor shaft 41 on the frame 20, a commutator 42 provided integrally with the rotor shaft 41, and a brush 43 attached to the frame 20 and elastically contacting the commutator 42. Having.

The above-described frame 20 has a pair of divided frames 21 and 21 formed of the same shape and the same size from a magnetic conductive material such as iron.
Having. This divided frame 21 is formed by sintering or precision casting. Here, in the case of sintering,
After the iron powder is press-molded in a mold, the press-formed product is fired to form the final divided frame 21.
In the case of precision casting, molten iron is injected into a cavity in a mold and cooled to form a final divided frame 21.

The divided frame 21 includes an intermediate wall 21a and the intermediate wall 21a.
Opposing walls 21b, 21 connected at right angles to both ends of
It is formed in a U-shape from b.

An arc-shaped surface 22 concentric with the rotor 40 is formed on a portion of the intermediate wall 21a facing the rotor 40 (see FIG. 3).
Numeral 22 is formed on the intermediate wall 21a when the divided frame 21 is molded as described above. The outer peripheral surface of the magnet 30 is bonded and fixed to the arc-shaped surface 22. This bonding can be performed with the divided frames 21 and 21 separated.

As shown in FIG. 2, semi-cylindrical recesses 23 and 24 having large and small diameters are formed coaxially on the end surface 21c of each of the opposed walls 21b. Positioned positioning hole
25 and a positioning protrusion 26 are formed. The recess 23 has a smaller diameter than the recess 24 and is located on the magnet 30 side.

Then, the end faces 21c, 21c of both opposing walls 21b, 21b of one divided frame 21 are connected to both opposing walls 21b, 21b of the other divided frame 21.
Of the one end face 21c to be fitted is fitted into the positioning hole 25 of the other end face 21c to be fitted. This allows the frame to be opened to the side with a substantially square side shape
20 is formed, and the combined opposing walls 21b, 21b form an end wall 27 of the frame 20.

Moreover, the end faces 21 of the opposing walls 21b, 21b
Arc-shaped surfaces 21d, 21d are formed on the surface opposite to c, 21c, and an end surface 27 formed by the opposed walls 21d, 21d is formed in an oval outer end surface 27a. A recess 21e is formed at the center of the arc-shaped surface 21d.

Further, by combining the divided frames 21, 21, a shaft insertion hole 28 is formed by the concave portion 23 of one divided frame and the concave portion 23 of the other divided frame 21, and the concave portion 24 of one divided frame and the other The recess 24 of the divided frame 21 forms a spigot portion 29 that opens to the outer end surface 27a of the end wall 27. The shaft insertion hole 28 and the spigot portion 29 are provided coaxially, and the shortest dimension from the center point A of the arcuate surface 21d to the spigot portion 29, that is, the point B of the recess 24, and the point A, B from the end face 21c.
And the dimensions up to the arcuate surface 22 are set accurately.

Then, the end of the rotor shaft 41 is inserted into the shaft insertion hole 28, and the end is rotatably held by the bearings 50, 50 engaged with the spigot portion 29. Moreover, the two opposing walls 21b, 21b
Is fixed by a cap 51 fitted to the outer peripheral surface of the end wall 27. Note that the cap 51 is fixed to the divided frames 21, 21 by caulking the center end 51b of the arc-shaped portion 51a into the recess 21e as shown in FIG.

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

According to such a configuration, the rotor 40 is disposed between the U-shaped divided frames 21b, 21b having the same shape and size, and both ends of the rotor 40 are simply sandwiched between the divided frames 21, 21. As a result, the rotor 40 is assembled to the frame 20.

Further, the magnet 30 is bonded to the arc-shaped surface 22 of the intermediate wall 21a in a state where the divided frames 21 and 21 are separated,
Be concentric with rotor 40. Thereby, the gap between the magnet 30 and the rotor 40 becomes uniform as a whole.

Further, arcuate surfaces 21d, 2 are provided on the mating surfaces of the opposing walls 21b, 21b, that is, the surfaces opposite to the end surfaces 21c, 21c.
By forming 1d, the outer end surface 27a is formed between the opposing walls 21b, 21b.
Forms an oval end wall 27, is coaxial with the shaft insertion hole 28 and is open to the outer end surface 27a of the end wall 27, and the shortest dimension from the center of the arcuate surface 21d is accurately set. Since the spigot portion 29 is formed between the opposed walls 21b, 21b, it is not necessary to increase the dimensional accuracy of the divided frame 21 as a whole. As a result, since it is not necessary to increase the processing accuracy of the mold for processing the divided frame 21 as a whole, the processing of the mold becomes easy.

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

Further, the magnet is concentric with the rotor by bonding the magnet to the arc-shaped surface of the intermediate wall in a state where the divided frame is separated. Thereby, the gap between the magnet and the rotor becomes uniform as a whole.

Further, by forming an arc-shaped surface on the surface opposite to the mating surface of the opposing walls that are mated with each other, an outer end surface forms an oval end wall between the opposing walls, and a shaft insertion hole and the shaft insertion hole. Since the spigot part which is coaxial with the shaft insertion hole and is open to the end face of the end wall and whose shortest dimension from the center of the arc-shaped surface is accurately set is formed between the opposed walls, the size of the divided frame is increased. There is no need to increase the accuracy as a whole. As a result, since it is not necessary to increase the processing accuracy of the mold for processing the divided frame as a whole, the processing of the mold is also facilitated. As a result, assembly dimensional accuracy can be obtained by simple processing.

[Brief description of the drawings]

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

Claims (3)

(57) [Claims] 1. A pair of divided frames having the same shape and the same size and formed in a U-shape formed by an intermediate wall and opposing walls connected at right angles to both ends of the intermediate wall in the same direction are prepared. The end faces of the opposed walls of the one divided frame are respectively aligned with the end faces of the opposed walls of the other divided frame to form a frame having a rectangular side surface and opening laterally, and the intermediate wall is formed. A DC motor, wherein a magnet is fixed to an opposing surface of the DC motor, and each end of a rotor shaft of a rotor disposed between the magnets is rotatably held between the aligned opposing walls. 2. An arcuate surface concentric with the rotor is formed on a portion of the intermediate wall facing the rotor, and the arcuate surface is formed on the intermediate wall when the divided frame is molded. The DC motor according to claim 1, wherein: 3. An arc-shaped surface is formed on the surface opposite to the mating surface of the mutually opposing opposing walls so that an outer end surface forms an oval end wall between the opposing walls, and a shaft is formed. Forming a slot between the opposed walls coaxially with the insertion hole and the shaft insertion hole and opened to the end face of the end wall, and the shortest dimension from the center of the arcuate surface is accurately set; The end of the rotor shaft inserted into the hole is rotatably held by a bearing engaged with the spigot portion, and the combined opposing walls are fixed by a cap fitted to the outer peripheral surface of the end wall. The DC motor according to claim 1.