JPS6096167A - Dc motor with speed regulating mechanism - Google Patents

Abstract

PURPOSE:To simply regulate the speed of a DC motor and to enable to simplify the structure of the motor by movably providing a movable piece made of a magnetic material outside a motor case, altering the magnetic flux by the movement of the piece, and varying the rotating speed. CONSTITUTION:An operating lever 8 which is disposed at the outside of a housing 9 is slid, thereby sliding a movable piece 7 on a motor case 6. When the position of the piece 7 is set to match the axial center of a permanent magnet 12 to the axial center of the piece 7 at this time, the magnetic flux emitted from the magnet 12 sufficiently passes the case 6 and the piece 7, and the magnetic leakage decreases so that the magnetic flux becomes maximum. Thus, the rotating speed of a rotor 14 becomes minimum at the rated torque. When the lever 8 is operated to displace the magnet 12 and the piece 7 to the not opposed position, the magnetic flux decreases to enhance the rotating speed of the rotor 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a DC motor with a speed adjustment mechanism used in electric shavers and various other appliances.

[Background technology]

Generally, as speed control means for a DC motor using a permanent magnet, there are methods such as a motor equipped with a frequency generator, a method that changes the applied voltage, and a method that inserts a resistor in series in the armature circuit. However, there are problems in that various circuit parts are required, the structure is complex, assembly is time-consuming, and costs are high.

Therefore, we attempted to utilize the following characteristics of the motor. Generally, as shown in Figure 1, in a DC motor that uses a permanent magnet L for the field, a magnetic flux H is completely passed through the motor case 2 to create a magnetic circuit, a magnetic field is created in the air gap 3, and the magnetic field is By passing current through the coil 5 wound around the iron core of the rotor 4, the rotor 4 is rotated. Here, if the wall thickness of the motor case 2 is thin, the magnetic flux density will increase and when it reaches a saturated state, magnetic leakage will increase and the magnetic field in the air gap 3 will weaken, that is, the magnetic flux H
decreases, and the rotational speed of the rotor 4 increases. Figure 2 shows its characteristics. A is a characteristic curve when the wall thickness of the motor case 2 is thin and magnetic leakage is large, and B is a characteristic curve when the wall thickness of the motor case 2 is sufficient and magnetic leakage is small. nA,
nB indicates the rotation speed at the rated torque in each of curves A and BK. Here, nA>nB. This invention utilizes this characteristic to make the rotation speed variable.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a DC motor with a simple speed adjustment mechanism that allows speed adjustment to be performed easily.

[Disclosure of the invention]

The DC motor with a speed adjustment mechanism of the present invention has a movable piece made of a magnetic material provided on the outside of the motor case, and the rotation speed is changed by changing the magnetic flux by moving the movable piece.

Embodiment An embodiment of the present invention is shown in FIGS. 3 to 5. In the figure, 6 is a motor case, into which a cylindrical movable piece 7 is fitted so as to be movable in the axial direction.

The movable piece 7 is made of a magnetic material such as iron, and has an operating lever 8 projecting therefrom. The motor 6 is fixed to the housing 9 of the electrical device, and the operating lever 81 protrudes from the opening 10 of the housing 9. 11 is a lead wire. Motor case 6
A permanent magnet 12 is fixed inside, and an iron core rotor 14 around which a coil 13 is wound is housed.The rotor 14 is attached to an output shaft 15. The axial length of the movable piece 7 is approximately the same as the axial length of the permanent magnet 12.

By sliding the operating lever 8 located outside the operating housing 9, the movable piece 7 slides on the motor case 6. At this time, the axial center of the movable piece 7 and the permanent magnet 1
If the position of the movable piece 7 is set so that it aligns with the axial center of the permanent magnet 12, the magnetic flux emitted from the permanent magnet 12 will sufficiently pass through the motor case 6 and the movable piece 7, reducing magnetic leakage and maximizing the magnetic flux. becomes. Therefore, rotor 1 at rated torque
The rotation speed of 4 is the lowest. In FIG. 6, the solid line C indicates the characteristics of the motor in this state.
When the center of the permanent magnet 12 and the movable piece 7 are shifted to a position where they no longer face each other, the magnetic flux emitted from the permanent magnet 12 can only pass through the inside of the motor case 6, so magnetic leakage increases. The magnetic flux is reduced and the rotational speed of the rotor 14 at rated torque is higher than in the matched condition. In FIG. 6, the chain line indicates the characteristics in this state. nλ and n6 each indicate the rotation speed at the rated torque. The rotation speed of the rotor 14 increases as the deviation between the center of the movable piece 7 and the center of the permanent magnet 12 increases.

In this way, the rotation speed can be easily changed by simply sliding the movable piece 7. Moreover, since it is only necessary to attach the movable piece 7, the structure is simple, no assembly effort is required, and manufacturing is possible at low cost.

FIG. 7 shows an electric shaver using the motor of the same embodiment. In the figure, 9 is the housing, 17 is the blade, 18 is the main switch, 19 is the battery, 20 is the metal fitting for the holder, 21
The lead wire is Ruru. When configured in this way, the movable blade (
This is useful when you want to lower the rotation speed of the blade (not shown) to a level that does not reduce sharpness and use it quietly while listening to the radio or the like.

@Figures 8 to 1O show other embodiments. This example:
An opening 22 is provided in one plane part of the motor case 6, and this opening 22 can be opened and closed by sliding a movable piece 23. The movable piece 23 is pressed against the motor case 6 by a spring 24. The other configurations are similar to the first embodiment. Even in the case of this configuration, FIGS. 11 and 1
As shown in FIG. 2, when the amount of deviation l between the centers of the movable piece 23 and the permanent magnet 12 is large, the magnetic flux φ becomes small and the rotational speed increases.

FIGS. 13 and 14 show other embodiments of ζ et al. In this example, a movable piece 23' having a substantially U-shaped cross section is provided, and an opening 22 is provided in the flat part on both sides of the motor case 6, and this opening 22 is opened and closed by a movable piece 23'. be. The movable piece 23' is fitted into the motor case 6 by the elasticity of both leg pieces 233'. The rest is the same as the first embodiment.

FIGS. 15 and 16 show still other embodiments. In this example, the movable piece 24 has a substantially U-shape in which both side pieces 24B are curved in a cylindrical shape, and its elasticity allows the motor case 6
It is fitted on both sides of the cylinder. The gap between the movable piece 24 and the motor case 6 in a portion other than the leg piece 2411 is set to about several microns to about 0.2 fl to facilitate the movement of the movable piece.

This gap is kept constant by fitting only the leg pieces into the motor case 6. The rest is the same as the first embodiment.

FIGS. 17 to 19 show still other embodiments. In this example, a permanent magnet 25fL is used as the magnetic body for the movable piece 25. The other configurations are similar to the first embodiment. When using the permanent magnet 2511,
The magnetic flux can be greatly increased or decreased by a small sliding amount of the movable piece 25, and the rotation speed can be increased or decreased. Furthermore, the permanent magnets 12 and 25 inside the motor case 6 and in the movable piece 25
The polarity of a is as shown in FIG.

FIG. 20 shows yet another embodiment. In this example, the movable piece 26 is formed of a cylindrical member 268 and a permanent magnet 2fl fixed to the inner surface thereof, and is rotatably fitted onto the motor case 6. In this case, by shifting the phase angle θ between the magnetic field direction X of the motor and the magnetic field direction X' of the movable piece 26, the rotation speed can be changed in the same manner as described above. FIG. 21 shows the relationship between the phase angle θ and the magnetic flux φ.

〔Effect of the invention〕

The DC motor with a speed adjustment mechanism of the present invention has the advantage that speed adjustment can be easily performed and the structure is simple.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional motor, Fig. 2 is an explanatory diagram showing the characteristics when the thickness of the motor case is changed, Fig. 3 is an exploded perspective view of an embodiment of the present invention, and Fig. 4 is the same. 5 is a cross-sectional view showing the inside of the housing, FIG. 6 is an explanatory diagram of its characteristics, and FIG. 7 is a cutaway front view of the electric shaver using the motor of the same embodiment. 8 is an exploded perspective view of another embodiment, FIG. 9 is a sectional view of the assembled state in the housing, FIG. 10 is an explanatory diagram of its operation, and FIGS. 11 and 12 are respectively its Special □
Fig. 13 is an exploded perspective view of another embodiment, Fig. 14 is a sectional view thereof, Fig. 15 is an exploded perspective view of still another embodiment, and Fig. 16 is a sectional view thereof. FIG. 17 is an exploded perspective view of still another embodiment, FIG. 18 is a cross-sectional view thereof, and FIG. 19 is a cross-sectional view of the assembled state in the housing.
FIG. 20 is a sectional view of still another embodiment, and FIG. 21 is an explanatory diagram of its characteristics. 6...Motor case, 7...Movable piece, 8...Operation lever, 9...Housing, 12...Permanent magnet, 1
4... Rotor, 22... Opening, 23.23'...
Movable piece, 23R'...Leg piece, 24-26...Movable piece, 258, 261%...Permanent magnet Agent Patent Attorney Akio Miyai Procedural Amendment (Spontaneous December 16, 1988) 058 Patent Application No. 202968 2, Title of invention: DC motor with speed adjustment ta structure 3, Person making the amendment Relationship to the case: Applicant 4, Attorney 5, Date of amendment order Voluntary amendment (2) No. 7 of the drawings Correct the figures as indicated in red on the attached sheet.

Claims (4)

[Claims] (1) A DC motor with a speed adjustment mechanism in which a movable piece made of a magnetic material is provided in the motor case to change the magnetic flux passing through the rotor. (2) The DC motor with a speed adjustment mechanism according to claim (1), wherein the movable piece has a cylindrical shape that is fitted onto the motor case. (3) Claim No. 1, wherein an opening is formed in the motor case, and the opening can be opened and closed by the movable piece.
A DC motor with a speed adjustment mechanism as described in . (4) The DC motor with a speed adjustment mechanism according to claim (1), wherein the movable piece has a U-shaped cross section and is elastically fitted to the motor case by the elasticity of the leg piece. (5) A DC motor with a speed adjustment mechanism according to claim (1), wherein the movable piece is formed of a permanent magnet.