JP2510549Z - - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor used for, for example, a shaver, a dryer, and the like. (Torque, life, etc.) and a thinner device. 2. Description of the Related Art FIG. 6 is a longitudinal sectional view of a main part showing an example of a small motor to which the present invention is applied. In FIG. 6, reference numeral 1 denotes a housing, which is formed of a metal material such as soft iron and has a hollow cylindrical shape with a bottom, and has a permanent magnet 2 formed, for example, in the shape of an arc segment fixed to the inner peripheral surface. In the housing 1, a rotor 5 including an armature 3 and a commutator 4 facing the permanent magnet 2 can be interposed. Reference numeral 6 denotes an end bracket, which is formed of an insulating material and is fitted into an opening of the housing 1. A brush 7 has a free end slidably engaged with the commutator 4 and is provided on the end bracket 6 together with an input terminal 8 electrically connected to the brush 7. Bearings 9 and 10 are fixed to the bottom of the housing 1 and the center of the end bracket 6 and rotatably support a shaft 11 constituting the rotor 5. With the above configuration, current is supplied from the input terminal 8 to the armature 3 via the commutator 4 constituting the rotor 5 via the brush 7, thereby being fixed to the inner peripheral surface of the housing 1. A rotating force is applied to the armature 3 existing in the magnetic field formed by the permanent magnet 2, the rotor 5 can be rotated, and an external device (not shown) is driven via the shaft 11. Can be. [0005] The small motor having the above-described structure has an excellent characteristic that the output is large and the speed and the positioning can be easily controlled by using an electronic circuit. .
On the other hand, since the commutator 4 rotates in a sliding state with respect to the brush 7, the commutator 4 has disadvantages that it is mutually worn and sparks are generated. [0006] In order to solve the above-mentioned drawbacks, a small motor having a spark quenching element has been conventionally proposed. FIG. 7 is a view showing an example of a rotor of a small motor provided with a conventional spark extinction element, wherein (a) shows a left side surface, (b) shows a front surface, and the same parts are denoted by the same reference numerals as those in FIG. Indicated by In FIG. 7, reference numeral 12 denotes a substrate, which is provided between the armature 3 and the commutator 4 and on which the electrolytic capacitor 13 is fixed. Note that, for example, three electrolytic capacitors 13 are connected as shown in FIG. In FIG. 9, reference numerals 14 are coils constituting the armature 3 shown in FIG. 6, which are respectively connected in parallel with the electrolytic capacitor 13. However, when the spark quenching element is configured as described above, a total of four parts including the substrate 12 and the three electrolytic capacitors 13 are required, and there is a disadvantage that the assembly is complicated. Further, as shown in FIG. 7, since the electrolytic capacitor 13 is interposed in the slot 3a of the armature 3, there is a space limitation. That is, the electrolytic capacitor 1
If the capacity of the coil 3b is increased, the linear product of the coil 3b for determining the torque of the small motor is limited. Also, the interposition of the electrolytic capacitor 13 allows the coil 3
There is also a disadvantage that the green coating of b is damaged and rare short is caused. Further, since the lead wire 13a of the electrolytic capacitor 13 protrudes from the substrate 12, there is a problem that the thinning of a small motor is hindered. FIG. 8 is an explanatory view showing another example of the spark extinction element. FIG. 8 (a) shows a plan view and FIG. 8 (b) shows a side view, which is disclosed in, for example, Japanese Utility Model Laid-Open Publication No. 51-14709. In FIG. 8, reference numeral 15 denotes a substrate, which is formed in a hollow disk shape by using an insulating material and has a plurality of electrodes 1.
6 is coated on the surface, and a chip capacitor 17 is placed on the electrode 16 respectively.
It is attached so as to straddle 16. However, when a large-capacity chip capacitor 17 is used, the thickness of the chip capacitor 17 becomes large, and the thickness of the substrate 15 needs to be correspondingly large. There is a problem that. Further, there is an example in which a washer-type varistor as disclosed in, for example, Japanese Utility Model Application Laid-Open No. Sho 51-42457 is used as a spark extinction element. This is one in which a plurality of divided electrodes are formed on at least the circumferential surface of a varistor body formed in a hollow disk shape. The varistor has a very small capacitance of, for example, about several tens nF. It is small. In the case of a high voltage of, for example, 30 V or more, the variation of the varistor voltage becomes extremely large, and the spark extinction action also varies. Further, the capacitance is in inverse proportion to the varistor voltage, and has a small value of, for example, about several nF. In general, in a small motor having a low voltage of, for example, 2.4 V or less, it is necessary to supply a large current to obtain a high output. In this case, if it is within the voltage range of 2.4 to 30 V,
The characteristic of the varistor can improve the life of the small motor. However, if a varistor is used in a small motor with a high voltage specification of 30 V or higher and a high current and high output specification of 2.4 V or lower as described above, the capacitance as a spark quenching element will be insufficient. Becomes As a result, the commutator 4 and the brush 7 (
However, there is a problem that the spark quenching effect between the small motor and the motor (see FIG. 6) becomes insufficient and cannot be a means for improving the life of the small motor. The present invention solves the above-mentioned problems in the prior art, and provides a small-sized motor in which the number of components of the spark extinction element is small, torque and life can be improved, and the thickness can be reduced. The purpose is to do. In order to achieve the above object, in the present invention, a housing formed into a hollow cylinder with a bottom and having a permanent magnet fixed to an inner peripheral surface thereof, and an armature are provided. A rotor comprising a spark quenching element and a commutator, a brush fitted into the opening of the housing and slidably in contact with the commutator, and an input terminal electrically connected to the brush. A small motor comprising: an end bracket made of a material; and wherein the rotor is rotatably supported via bearings provided on the housing and the end bracket. The formed thin plate and the internal electrodes formed in the shape of a fan of a thin film of conductive material are alternately laminated in the axial direction, and the number of internal electrodes corresponding to the number of poles of the armature on the projection plane orthogonal to the axis With polar polymer portion is formed, providing the internal electrodes and the electrode connected to the outer peripheral surface of the thin plate, the 30V
The technical means of using a multilayer ceramic capacitor having a high voltage specification exceeding and having a capacitance of 1 μF or more was adopted. The high dielectric ceramic materials include titanium oxide, magnesium titanate,
Although calcium titanate, strontium titanate, barium titanate, lead titanate, lead zirconate and the like can be used, it is preferable to use barium titanate having a relatively large dielectric constant. Next, if the capacitance of the capacitor is less than 1 μF, the effect of improving the life of the small motor cannot be expected, which is not preferable. That is, for example, in a small motor for a shaver and a drier,
A 50-hour guarantee is required, and 300 hours is a passing criterion for safety. If the capacitance of the capacitor is less than 1 μF, the above-mentioned acceptance criterion will not be reached. Therefore, in the present invention, the capacitance of the capacitor is specified to be 1 μF or more. According to the above configuration, it is possible to sufficiently secure a spark quenching effect required as a spark quenching element, to improve the life of a small motor, and to achieve a reduction in the number of components and a reduction in thickness. . FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, and FIG. 2 is an exploded perspective view showing essential components in FIG. 1. The same parts are shown in FIG. 6 and FIG. Are indicated by the same reference numerals. In FIGS. 1 and 2, reference numeral 18 denotes a spark quenching element, which is constituted by a multilayer ceramic capacitor made of a high dielectric ceramic material such as barium titanate as described later. That is, the spark quenching elements 18 are formed in a hollow disk shape, and the number of electrodes 19 (three in this embodiment) corresponding to the number of poles of the armature 3 is formed on the outer peripheral surface.
Is provided. FIG. 3 is an enlarged perspective view showing the spark quenching element 18 in FIGS. 1 and 2 partially cut away, FIG. 4 is an explanatory view showing the configuration of the internal electrode of the spark quenching element 18, and FIG. FIG. 3 is a plan view showing constituent members of an erasing element 18. 3 to FIG.
Is a thin plate made of a high dielectric ceramic material such as barium titanate.
It is formed in the shape of a hollow disk. Reference numeral 21 denotes an internal electrode, which is formed, for example, in a fan shape with a central angle of 180 °, and has a terminal 22 provided so as to face the outer peripheral surface. And the thin plate 20 and the internal electrode 21
Are alternately laminated, and a capacitor is formed by a portion (indicated by hatching) where the internal electrodes 21 overlap as shown in FIG. An electrode 23 connects the terminal 22 and is electrically connected to the commutator 4 and the armature 3 shown in FIG. As shown in FIGS. 1 and 2, a small motor in which the spark quenching element 18 formed as described above is incorporated in the rotor 5 as shown in FIGS.
The results of continuous operation with a 0 g fan load applied are shown below. In this case, I ₀ = 210 mA and N ₀ = 22,000 rpm. [0020] As described above, in (5) lacking the spark quenching element, the life is only 50 hours, and in (4) using a varistor, the life is extended to 200 hours. However, since the capacitance is 0.01 μF, the spark quenching action is insufficient. On the other hand, in (1) to (3) in which the spark quenching element is formed by the multilayer ceramic capacitor formed as described above, since the capacitance is large, the spark quenching effect is large, and the life is short. Is increasing. By making the capacitance 1 μF or more,
It is recognized that the passing criteria of 300 h are completely cleared and the life is remarkably increased. In the present embodiment, an example is described in which the outer peripheral contour of the spark extinction element is formed in a circular shape. However, a geometric shape other than a circular shape may be used. Further, the thickness and the number of stacked thin plates constituting the spark quenching element can be appropriately selected according to the specifications of the small motor. The materials constituting the thin plate and the internal electrodes of the spark quenching element are not limited to the present embodiment, but can be appropriately selected in the same manner as described above. Advantages of the Invention The present invention has the configuration and operation as described above, and therefore has the following effects. (1) Since the configuration of the spark extinction element is extremely simple, there is no need to attach a large number of parts as in the conventional one, and the number of assembling steps can be reduced. (2) Since the thickness of the spark extinction element in the axial direction is small, it is possible to reduce the size of the small motor, and it is possible to increase the line area of the coil, thereby increasing the torque. (3) Since the capacitance of the spark quenching element is large, the spark quenching effect is remarkable, and the life can be greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention. FIG. 2 is an exploded perspective view showing essential components of FIG. 1; FIG. 3 is an enlarged perspective view showing a partially cutaway view of the spark extinction element in FIGS. 1 and 2; FIG. 4 is an explanatory diagram showing a configuration of an internal electrode of the spark extinction element in FIGS. 1 and 2; FIG. 5 is a plan view showing constituent members of the spark extinction element in FIGS. 1 and 2. FIG. 6 is a vertical sectional view of a main part showing an example of a small motor to which the present invention is applied. FIG. 7 is a view showing an example of a rotor of a small motor having a conventional spark extinction element, and (a).
Indicates a left side, and (b) indicates a front. FIGS. 8A and 8B are explanatory diagrams showing another example of the spark elimination element, wherein FIG. 8A shows a plane and FIG. FIG. 9 is an equivalent circuit diagram showing a connection state of a capacitor and a coil. [Description of Signs] 18 Spark extinction element 20 Thin plate 21 Internal electrode

Claims (1)

[Claim 1] A rotor formed of a hollow cylinder with a bottom and having a permanent magnet fixed to an inner peripheral surface thereof, and a rotor comprising an armature, a spark quenching element, and a commutator. And an end bracket provided with a brush fitted into the opening of the housing and slidably contacting the commutator, and an input terminal electrically connected to the brush.
A small motor in which the rotor is rotatably supported via bearings provided in the housing and the end bracket, wherein a spark quenching element is formed into a hollow plate made of a high dielectric ceramic material, and a conductive material. And an internal electrode formed in a fan shape of a thin film is alternately laminated in the axial direction to form a number of internal electrode overlaps corresponding to the number of poles of the armature on a projection plane orthogonal to the axis. An electrode connected to the internal electrode is provided on the surface, and 30 V is applied.
A small motor comprising a multilayer ceramic capacitor having a high voltage specification exceeding 1 μF and a capacitance of 1 μF or more.