JPH0642776B2 - DC motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a DC motor, and more particularly to an arrangement of a rotational position detection sensor of a rotor for controlling a timing of energizing a coil.

[Background Art] In a DC motor, a rotational position detection sensor for detecting the rotational position of the rotor is required to control the timing of energizing the coil. As the rotational position detection sensor for the rotor, a magnetic sensitive element is used. There are a non-contact type and a mechanical type. As the latter rotational position detection sensor, a rectifying device which is attached to the rotor shaft and rotates together with the rotor, and a brush provided in sliding contact with a segment provided on the rotor is generally used. However, conventionally, with a rotor,
A rotational position detection sensor is arranged between the rotor and a bearing that supports one end of the shaft.

In this case, the outside air flows into the housing portion of the rotor due to the rotation and stop of the rotor, and the dust is also sucked at this time, but this dust adheres to the rotation position detection sensor and the segment and the brush are separated from each other. The mechanical contact between them may be affected to cause malfunction.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to prevent the dust that enters the housing chamber of the rotor from adhering to the rotation position detection sensor, and It is an object of the present invention to provide a DC motor that does not cause a malfunction due to.

DISCLOSURE OF THE INVENTION The present invention has a magnetic circuit forming portion including a stator S having a coil 7 and a rotor R having a magnet 1, and is attached to a shaft 2 of the rotor R to rotate with the rotor R. The rotor R has a rotational position detecting sensor including a rotating body C, and brushes 13 and 14 slidably contacting the segments 19 and 20 provided on the rotating body C. In the direct current motor controlling the energization timing, the rotor R of the magnetic circuit forming portion and the rotational position detection sensor are partitioned by a partition wall composed of a bearing stand 8 for supporting the rotor,
The rotational position detection sensor is characterized in that it is housed in a recess 12 formed on the surface of the bearing base 8 opposite to the rotor R and covered by a circuit block P. The block is used to isolate the rotational position detection sensor from the rotor.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiment of a two-pole DC motor. A rotor R having axially opposite ends supported by bearing base blocks Ba and Bb and a stator S disposed around the rotor R.
Is composed of a magnet 1 fixed to a shaft 2. The coupling between the magnet 1 and the shaft 2 is selected according to the strength of the magnet 1. If the magnet 1 is a plastic magnet, press fitting, die casting or co-molding for a cast magnet, bonding for a sintered magnet, or It is made by means of potting, simultaneous molding, die casting, etc., but in the case of the illustrated example, it is made by potting of an adhesive resin such as epoxy resin. Reference numeral 41 in FIG. 3 denotes a potting resin filled between the inner peripheral surface of the magnet 1 and the shaft 2. Reference numeral 3 in the drawing denotes a potting resin 41 outflow preventing member, which is provided in a pair at both ends of the magnet 1 and is adhered and fixed at the same time as the potting to prevent outflow of the potting resin and to prevent the rotor R from rotating. It is designed so that the dimensional accuracy in the axial direction can be obtained. Reference numeral 36 is a bush for attaching a load member such as a fan to the shaft 2.

The stator S surrounding the outer periphery of the rotor R is composed of a pair of stator blocks Sa and Sb. Both stator blocks Sa and Sb have a shape that is point-symmetric with respect to the axis 2, and are both formed of an iron core 4 and a coil 7. Both iron cores 4 are of a laminated type, and are caulked and fixed by caulking pins 5. A groove 47 that is long in the axial direction of the rotor R is formed on the outer surfaces of the two iron cores 4, a semicircular groove 45 that serves as a space for disposing the rotor R is formed in the center of the opposing surface, and a space for disposing the coil 7 is provided on the opposite sides of the opposing surface. Recessed grooves 46, 46 are provided respectively. The coils 7 are arranged in the recessed grooves 46 in which the insulating paper 6 is inserted. Here, both coils 7 are rectangular loop-shaped ones, and both ends in the longitudinal direction are bent by approximately 90 degrees in the same direction to form a front shape. Is a square shape, and the end surface shape and the side surface shape are U-shaped, and both side pieces are arranged in the groove 46 and both ends are arranged on both end surfaces of the iron core 4. is there. It should be noted that the insulating paper 6 and the caulking pin 5 may be eliminated and the iron core 4 may be fixed by simultaneous molding, which can be arbitrarily selected in relation to the number of manufactured pieces.

Bearing base block Bb arranged at one end of the shaft 2 of the rotor R
Is a bearing stand 8 on which projecting pieces 48, 48 project from both ends in the axial direction of the rotor R, an oil-impregnated felt (not shown), a bearing 9, a spring 11 for pressing the bearing 9, and an impact load. It is composed of a stopper 10 for suppressing the displacement of the shaft 2 below the elastic limit of the spring 11. The other bearing block B
a is a bearing base 8 similarly provided with protruding pieces 48, 48, an oil-impregnated felt disposed on the surface of the rotor R side thereof, and a bearing 9
Etc. In FIG. 2, 32 is a spacer for reducing the friction between the rotor R and the bearing 9 in the thrust direction, and 33 is an oil spacer for preventing oil of the bearing 9 from adhering to the rotor R or the like. Is. The bearing base 8 in the bearing base block Ba has a recess 12 formed on the surface opposite to the rotor R side, and the coil terminal 1
7, a boss 16 and the like are provided, and a rotational position detection sensor for the rotor R is arranged in the recess 12.

This sensor performs mechanical detection, and includes a rotor C attached to the end of the shaft 2 of the rotor R, and a pair of axially arranged segments 19 provided on the outer peripheral surface of the rotor C. , A pair of brushes 1 that respectively contact the brushes 20
3 and 14 are used. Both segments 19, 20
Are integrally connected to each other, but an insulating portion made of resin 18 integrally molded with these segments 19 and 20 is located between them, and the segment 19 has a continuous outer peripheral surface. However, the segment 20 has a slit formed in the middle and is divided in the circumferential direction, and a part of the segment 20 is also separated from the segment 19. Each of the brushes 13 and 14 fixed to the bearing base 8 by the brush-shaped brush fixing ring 15 is formed of a wire spring. Among these, the pair of brushes 13 connected to the anode is a rotating body. On the outer peripheral surface of the segment 19 in C,
The pair of brushes 14 connected to the cathode contacts the outer peripheral surface of the segment 20.

The two bearing stand blocks Ba and Bb are arranged on the outer surface of the end of the iron core 4 in the stator S and in the space between the coils 7 located on the outer surface of the end, and the protruding pieces 48 are made of iron. The fixing bolt 31 and the nut 3 which are fitted into the groove 47 on the outer surface of the core 4 and penetrate the bearing pedestals 8 and 8 and the iron core 4
5, the bearing base 8 in the bearing base block Ba, on which the sensor is arranged, is covered by the circuit board 29 so as to cover the recess 12 on which the sensor is arranged.
The circuit block P is attached. This circuit block P
Is a circuit board 29 fixed by fitting the bearing base 8 with the boss 16 and heat staking the boss 16, and the triac 2
8, a rectifying stack 27, a power transistor 21, a surge absorbing capacitor 22 and a varistor 23, a power source smoothing capacitor 26, and other circuit components. Lead wires 40 and the like for connecting to the variable resistor are drawn out.
The coil terminal 17 of the bearing stand Ba is directly connected to the printed board 29.

Now, in the motor of the illustrated example formed in this way,
Since the bearing base 8 having the bearing 9 is located between the sensor and the rotor R, and the rotor R and the sensor are partitioned by the bearing base 8, air generated when the rotor R is rotated or stopped is separated. Even if dust flows from the outside into the accommodating portion of the rotor R due to the flow, the dust does not reach the sensor side, and the segments 19 and 20 of the rotor C that control the energization timing to the coils 7 and 7 Attached segment 1
The contact between the brushes 9 and 20 and the brushes 13 and 14 will not be obstructed by dust, and the above-mentioned sensor is used in the circuit board 29 of the bearing stand 8 as described above.
Since it is arranged in the recess 12 covered with, the dust does not reach the sensor part from other directions.

Further, in the motor of the above embodiment, both ends of each coil 7 are exposed outside both ends of the iron core 4, that is, protruding in the thrust direction, but the end face shape when combined is rectangular. Both ends of each coil 7 are bent in the radial direction, that is, in the lateral direction of the iron core 4, with respect to the iron core 4 forming When the stator S is viewed from the end face, as shown in FIGS. 4 and 5, the inner faces at both ends of the coil 7,
A gap K is formed between the iron core 4 and the outer surface of the iron core 4, and the end surface of the entire stator S has a rectangular iron core 4 and an outer surface in the lateral direction of the iron core 4. The protruding coil 7 forms a substantially square shape.

The magnet 1 in the rotor R is not magnetized before assembling with the stator S, but is magnetized after being combined with the stator S. When the rotor R after being magnetized is assembled to the stator S, the attraction force acting between the magnet 1 and the iron core 4 causes the magnet 1 to hit the iron core 4 and cause the magnet 1 to be chipped, and the shaft 2 and bearing 9
This is because it is difficult to fit the rotor R, the stator S, and the bearing bases 8 and 8 to each other. The magnet 1 is arranged between the yokes 55, and the magnet 1 is magnetized through the iron core 4. In this case, the magnet 1 has an NS pole formed so as to substantially face the magnetic pole of the stator S, and after the magnetizing magnetic field is removed, the N pole of the magnet 1 is removed.
The S pole is stopped in a state where it faces a small magnetic pole gap of the stator S. In this state, support one end of the shaft 2,
The rotor C is press-fitted to the other end of the shaft 2 with the outer side of the iron core 4 as a reference. If the magnetizing is performed after the assembling in this way, not only the assembling of the rotor R and the stator S becomes easy, but also the demagnetization of the magnet 1 is reduced because the vermance of the rotor R is increased, and therefore the magnet having a small coercive force is obtained. Since the material can be used, it is advantageous in terms of cost. Further, when the rotating body C is attached as described above, the rotating body C is attached with reference to the stop position (starting position) of the rotor R.
The variation in the positions of the magnetic poles and the rotating body C is reduced, and the rotating body C can be easily adjusted.

7 to 9 show another example of the brushes 13 and 14 in the sensor for detecting the rotational position of the rotor R. When the brushes 13 and 14 are formed by wire springs, The contact with the segments 19 and 20 is one point contact,
Since the reliability with respect to conduction is not so high, a U-shaped wire 57 is fixed by welding to the tips of the brushes 13 and 14 made of wire springs, and the pair of tips of the wire 57 contacts the segments 19 and 20. As described above, that is, multi-point contact is made, and the reliability of conduction is improved.

As described above, in the present invention, even if dust is sucked in when the outside air flows into the housing chamber of the rotor due to the rotation or stop of the rotor, the rotation position detection sensor is a partition wall composed of a bearing base from the rotor. The dust is not attached to the rotational position detection sensor because it is located in the partition and is housed in the recess provided on the opposite side of the rotor in the bearing base and covered by the circuit block. Therefore, there is little risk of malfunction due to the dust sucked into the motor adhering to the rotation position detection sensor, and the rotating body in the rotation position detection sensor should be mounted from the outside of the bearing stand. Therefore, it is easy to not only attach the rotating body but also to position it, making it easier to improve the quality, and also to rotate the bearing stand as a partition wall and the lid as a lid. To use the block, without requiring an additional member for dustproof, although capable reliable dustproof against rotational position detecting sensor, in which the number of parts is small.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an embodiment of the present invention, FIG. 2 is an exploded perspective view of the same, FIG. 3 is a cutaway front view of the same, and FIG. FIG. 5 is a plan view showing a state where the bearing base of the same is removed, FIG. 6 is a front view showing a magnetized state of the same, and FIG. An exploded perspective view of an example, FIG. 8 is a perspective view of the above, FIGS. 9 (a) and 9 (b) are a plan view and a side view of the same brush, 4 is an iron core, and 7 is a core.
Is a coil, 8 is a bearing stand, 13 and 14 are brushes, 19 and 20
Indicates a segment, and C indicates a rotating body.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhisa Aoki 1048, Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works, Ltd. (72) Nobuyasu Kubo, 1048, Kadoma, Kadoma City, Osaka Matsushita Electric Works, Ltd. (56 ) References Actual development Sho 54-81407 (JP, U) Actual development Sho 55-178277 (JP, U)

Claims (2)

[Claims] 1. A stator (S) having a coil (7) and a magnet (1)
And a rotor (R) having a magnetic circuit forming portion, and the rotor (R) is attached to the shaft (2) of the rotor (R).
Rotational position detection sensor of rotor (R) consisting of rotating body (C) rotating with (R) and brushes (13, 14) slidingly contacting segments (19, 20) provided in this rotating body (C) In a direct current motor that has a rotary position detection sensor and controls the timing of energizing the coil (7), the rotor between the rotor (R) of the magnetic circuit forming part and the rotation position detection sensor is used for supporting the rotor. It is partitioned by the partition wall consisting of the bearing base (8) of the above, and the rotational position detection sensor is formed on the surface of the bearing base (8) opposite to the rotor (R) and the circuit block (P).
A direct-current motor, characterized in that it is housed in a recess (12) which is covered with a. 2. The brush (13, 14) is formed of a wire spring,
The direct current motor according to claim 1, wherein the multi-pronged tip is a sliding contact portion with the segment (19, 20).