JPH06296357A - Small-sized motor - Google Patents

Abstract

PURPOSE:To prevent a productive defect in assembling, in which pushing force of an elastic member for absorbing the oscillation of a rotor in the axial direc tion can be adjusted with ease. CONSTITUTION:A small motor comprises a case 2 having a stator 3 in the inside thereof, a rotor 21 having a rotating shaft 5 mounted pivotally with bearing members 6 and 7 in the case 2, a bent washer 8 fitted on the rotating shaft 5 for pushing the rotor 21 in an axial direction, and a bush 64 fitted from a projected end part 63 of the rotating shaft 5 elongated from the bearing member 6 and mounted on the rotating shaft 5 for adjusting the pushing force of the bent washer 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary small motor such as a stepping motor, and more particularly to a preload mechanism for axially urging its rotor.

[0002]

2. Description of the Related Art Small rotary motors are widely used in various fields such as precision equipment such as small cameras, audio / visual equipment such as VTRs, and electrical equipment for automobiles. Also,
Stepping motors, which are a type of small motors, are widely used as a drive source for office equipment such as printers, facsimiles and typewriters, and various other equipment.

9 and 10 are views showing a conventional small motor, FIG. 9 is a sectional view of a stepping motor, and FIG. 10 is a partially enlarged sectional view of FIG. As shown in FIG. 9, an annular stator 3 is attached inside the casing 2 of the stepping motor 1, and a rotor 4 is arranged inside the stator 3. The rotating shaft 5 of the rotor 4 is the casing 2
It is rotatably supported by bearing members 6 and 7 provided on the. An elastic member such as a bending washer (washer) 8 having a spring force is fitted on the rotating shaft 5. The rotor 4 is configured to rotate while being axially biased by the spring force of the bending washer 8.

It is necessary to adjust the distance between the rotor 4 and both bearing members 6 and 7 so that the spring force of the bending washer 8 acts effectively. The adjustment of the spring force is performed by preliminarily mounting it on the rotary shaft 5 by appropriately predicting the thickness and the number of flat washers 9, 10, 11 called adjustment washers.

In the stepping motor 1 having the above-described structure, the rotor 4 is mounted inside the casing 2 and the rotor 4 is supported by the bearing members 6 and 7, and then the casing 2 is integrated by caulking or welding. It is assembled by fixing to.

[0006]

However, in the conventional stepping motor 1 as shown in FIG. 9, the dimensional error of the casing 2, the bearing members 6, 7 and the rotor 4 and the error of the mounting dimensions of the bearing members 6, 7 are erroneous. Therefore, as shown in FIG. 10, the interval D for mounting the bending washer 8 may become larger than the free height H of the bending washer 8. In such a state, the spring force of the bending washer 8 does not act on the rotor 4, and the rotor 4 vibrates violently in the axial direction and produces an abnormal sound.

On the other hand, if the distance D is too smaller than the free height H of the bending washer 8, the rotor 4 receives an excessive spring force from the bending washer 8, and torque cross occurs or in extreme cases. The rotor 4 may not be able to rotate due to frictional resistance.

In this way, the adjustment washers 9, 10,
In the conventional structure in which the bending washer 8 is preliminarily mounted with the expected thickness 11 to adjust the spring force, the spring force cannot be corrected even if the above-mentioned trouble occurs after the assembly is completed, resulting in a defective assembly. Therefore, the adjustment work of the distance D must be performed very carefully.

The present invention has been made to solve the above problems, and it is possible to easily adjust the urging force of the elastic member for preventing axial vibration of the rotor to prevent assembly failure. It is intended to provide a small motor.

[0010]

In order to achieve the above-mentioned object, a small motor of the present invention comprises a casing having a stator mounted therein, and a bearing arranged in the casing and provided in the casing. A rotor having a rotating shaft rotatably supported by a member; an elastic member fitted to the rotating shaft to axially bias the rotor; and the rotating shaft projecting outward from the bearing member. And an urging force adjusting member which is attached to the rotary shaft from an end portion of the urging member and adjusts the urging force of the elastic member.

[0011]

In the present invention, if the biasing force adjusting member is attached to the rotary shaft from the end of the rotary shaft protruding outward from the bearing member, the biasing force adjusting member is positioned at an arbitrary position in the axial direction of the rotary shaft. To be done. In this case, since the urging force adjusting member has its axial position regulated by the bearing member, if the rotating shaft is moved relative to the urging force adjusting member, the rotating shaft and the rotating body including the rotating shaft will move. The movement is adjusted in the axial direction with respect to the bearing member and the casing. As a result, the interval for mounting the elastic member is adjusted to the optimum dimension,
The rotor makes a rotational motion while being constantly biased in the axial direction by an appropriate biasing force.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A small motor according to the present invention will be described below with reference to FIGS. 1 to 8 by taking a stepping motor provided in a printer, a facsimile, a typewriter or the like as an example.

1 to 6 are views showing a first embodiment of the present invention, FIG. 1 is a sectional view of a stepping motor, and FIG. 2 is a perspective view showing its appearance. The illustrated stepping motor 20 is a motor called PM type (Permanent Magnet Type), and has a structure in which a rotor made of a permanent magnet is attracted and rotated by an electromagnetic force generated by a stator winding. .

As shown in FIGS. 1 and 2, the casing 2
A stator 3 is mounted inside the rotor 3, and a rotor 21 located inside the stator 3 is disposed inside the casing 2. The rotating shaft 5, which is fixed to the center of the rotor 21 in the axial direction, includes a bearing member 6 provided in the casing 2.
It is rotatably supported by 7. A mounting plate 23 is fixed to one substantially circular side surface 22 of the casing 2. A screw 25 is inserted in the through hole 24 formed in the mounting plate 23.
The stepping motor 20 is attached to the chassis 26 by inserting it into the chassis 26 such as an electronic device (not shown). In the stepping motor 20,
A wiring 27 for supplying current can be connected.

The casing 2 is formed of a housing 31 formed of a ferromagnetic metal material in the shape of a hollow cylinder with a bottom, and the same metal material as the housing 31, and is caulked or welded to the opening 32 of the housing 31. And a lid member 33 fixed by, for example. Lid member 33
The bearing member 6 fixed to the circular mounting hole 34 formed in the central portion of the housing 31 and the bearing member 7 fixed to the mounting hole 35 formed in the central portion of the side surface 22 of the housing 31 have a lubricating property. The bearing is an oilless type bearing formed of powdered sintered metal or powdered sintered alloy impregnated with resin or lubricating oil. Then, the rotary shaft 5 is formed by each bearing member 6,
It is rotatable with respect to 7 and movable in the axial direction.

The stator 3 includes a housing 31 and a lid member 3.
A first block 41 and a second block 42 which are fixed to the inner surface of the shaft 3, are arranged in parallel in the axial direction, and are arranged to face each other
It consists of The annular exciting coil 43 of the first block 41 is wound around an annular coil bobbin 44 whose outer peripheral portion is open. The pair of stator cores 45 that house and support the coil bobbins 44 are made of a ferromagnetic metal material, and as shown in FIG. 3, an annular disc portion 46.
And a plurality of comb-shaped magnetic poles 48 projecting from the inner peripheral edge 47 of the disk portion 46 in one direction parallel to the central axis and uniformly arranged around the inner peripheral edge 47. The pair of stator cores 45 are arranged so as to face each other, and the comb-shaped magnetic poles 48 are arranged so as to mesh with each other with a predetermined gap. In addition, the first block 41 of the stator 3 is configured by housing the coil bobbin 44 having the annular excitation coil 43 in the space formed by the large number of cylindrical magnetic poles 48 and the both disk portions 46. The second block 42 adjacent to the first block 41 also has the same configuration as the first block 41.

A substrate 49 for electrically connecting the annular exciting coil 43 and the wiring 27 is fixed to the coil bobbin 44 and protrudes outside the housing 31.
Since the connector 50 of the substrate 49 and the annular exciting coil 43 are electrically connected via the terminals attached to the substrate 49, if the wiring 27 is connected to the connector 50, the first
Annular excitation coil 43 of block 41 and second block 42
A current is supplied to each of the annular exciting coils 43 of.

In the first block 41, the housing 31 and the disk portions 46 and the comb-shaped magnetic poles 48 of the pair of stator cores 45 allow the magnetic flux generated by the exciting coil 43 of the first block 41 to pass through the first magnetic field. A circuit is formed. On the other hand, also in the second block 42, the housing 3
1 and the disk portion 46 and the comb-shaped magnetic pole 48 of the pair of stator cores 45, the exciting coil 4 of the second block 42
A second magnetic circuit is formed through which the magnetic flux generated by 3 passes.

Therefore, the first and second blocks 41, 4
If currents whose phases are deviated from each other are applied to the two exciting coils 43, the exciting coils 43 are alternately excited to generate the first and second exciting coils 43.
Magnetic force is generated alternately in the magnetic circuit.

The rotor 21 arranged radially inward of the stator core 45 is a cylindrical type formed of permanent magnets in which a plurality of magnetic poles extending in a direction parallel to the central axis of rotation are arranged in the circumferential direction. A rotor magnet 51 is provided. That is,
The rotor magnet 51 is obtained by evenly performing multi-pole magnetization by alternately arranging N poles and S poles on a cylindrical outer peripheral surface, and a polar anisotropy or radial anisotropy ferrite magnet is used for this. It is used.

The rotor 21 shown in FIG. 1 has a hollow cylindrical ferrite magnet 52 and a rotary shaft 5 as shown in FIG.
The rotor magnet 51 is integrated by fixing the middle piece 53 between the and. As shown in FIG. 5, when the rotor magnet 51a can be directly fixed to the rotating shaft 5, the rotor 21 has a rotor magnet 51a.
May be formed into a bottomed tubular shape, and an engaging portion 54 that engages with the rotating shaft 5 may be formed at the center of rotation thereof to fix the rotating shaft 5 to the engaging portion 54. By doing so, it is not necessary to use the middle piece, and the weight of the rotor 21a can be reduced.

The stepping motor 20 having the above structure
In, in the first and second blocks 41 and 42, when currents whose phases are shifted from each other are applied to the respective exciting coils 43, the respective stator cores 45 which are excited by the respective exciting coils 43
The position of the comb-shaped magnetic pole 48 is shifted by a predetermined step angle. Then, the rotor magnet 51 of the rotor 21 is attracted by the comb-teeth magnetic pole 48, and the rotor 21 makes a rotational movement by a predetermined step angle. Accordingly, it is possible to drive an electronic device or the like via the output unit 5a of the rotating shaft 5 that rotates.

Next, a so-called preload mechanism for constantly urging the rotor 21 in the axial direction (C direction) by an appropriate urging force will be described with reference to FIGS. 1 and 6. A bending washer (washer) 8 as an elastic member is arranged between one end surface 61 of the rotor magnet 51 of the rotor 21 and the bearing member 6. The bending washer 8 formed in a substantially dish shape has a spring force as an urging force, and this spring force urges the rotor 21 in the axial direction. The bending washer 8 may be press-fitted into the rotating shaft 5 and rotated together with the rotating shaft 5, but may be loosely fitted to be in a non-rotating state.

The bending washer 8 is formed of elastic spring steel or the like, but the bearing members 6 and 7 are oil-less oil-impregnated bearings made of the above metal, or an iron-based, copper-based or brass-based metal material. When it is formed by, it is necessary to prevent abrasion and noise due to metal contact between the bending washer 8 and the bearing member 6 and direct contact between the bending washer 8 and the rotor magnet 51. For this reason, washers 62 made of, for example, polyester resin and fitted on the rotary shaft 5 are provided on the front and rear surfaces of the bending washer 8, respectively. The conventional adjustment washers 9 and 10 shown in FIGS. 9 and 10 require extremely precise adjustment of the thickness and the number of sheets, but in the present invention, it is not necessary to adjust the thickness of the washer 62.

Further, the stepping motor 20 of the present invention
Includes a biasing force adjusting member that is mounted on the rotary shaft 5 from the end 63 of the rotary shaft 5 protruding outward from the bearing member 6 and that adjusts the biasing force (spring force) of the bending washer 8. In this embodiment, the bush 64 is used as the biasing force adjusting member. The bush 64 is press-fitted from the end 63 of the rotary shaft 5 and the rotary shaft 5 is relatively moved to the bush 64 side, and a detector such as a dial gauge is attached to the end 63 of the rotary shaft 5.
If the moving distance of the rotary shaft 5 is finely adjusted while detecting the biasing force of the bending washer 8 by contacting the rotor with the bending washer 8, the bending washer 8 axially attaches the rotor 21 through the both washers 62 with an appropriate biasing force. It will be a force.

Since the bush 64 is made of metal such as brass, in order to avoid direct contact with the metal bearing member 6, the bush 64 and the bearing member 6 are fitted to the rotary shaft 5. In addition, it is preferable to interpose a washer 65 made of a polyester resin having lubricity. When the rotary shaft 5 rotates, the bush 64 rotates integrally with the rotary shaft 5, but the washer 65 may or may not rotate. Although the bush 64 is press-fitted into the rotary shaft 5 in this embodiment, the biasing force adjusting member may be a screw-type or any other structure as long as it can be fixed to the rotary shaft 5 at any position in the axial direction. It may be one.

Next, one example of a procedure for assembling the stepping motor 20 having the above-mentioned structure will be described. First,
The stator 3 is mounted inside the housing 31 to which the mounting plate 23 is fixed. The bearing members 6 and 7 are attached to the lid member 33 and the housing 31 in advance. next,
The rotating shaft 5 has a washer 62, a bending washer 8, and a washer 6.
The rotor 21 is mounted inside the housing 31 by inserting the rotating shaft 5 into the bearing member 7 after fitting the two in order. Then, the lid member 33 is mounted in the opening 32 of the housing 31 while fitting the bearing member 6 to the rotary shaft 5, and the mounting portion is fixed by welding or the like.

At the time of mounting the lid member 33, it was necessary to strictly adjust the distance D for attaching the bending washer 8 in the past, but the distance D is not necessary to be adjusted in the present invention. That is, the interval D is determined by a rough dimension such that the biasing force of the bending washer 8 does not work in the state where the lid member 33 is attached, and then the end portion 63 of the rotary shaft 5 is inserted into the washer 6.
5 is mounted and the bush 64 is press-fitted. At the same time, the rotary shaft 5 is relatively moved toward the bush 64 side while finely adjusting the position of the bush 64 so that the biasing force of the bending washer 8 acts appropriately. Thus, the assembly of the stepping motor 20 is completed.

As described above, in this embodiment, after the rotor 21 is installed inside the casing 2, the bush 64 is attached from the outside of the casing 2 to adjust the biasing force of the bending washer 8. Optimal bias can be achieved. Therefore, the assembling work becomes extremely simple, and it is possible to prevent the problem that the rotor 21 vibrates in the axial direction to generate an abnormal sound. In addition, there is a problem that the dimension of the interval D for mounting the bending washer 8 becomes too small and the rotor 21 receives excessive urging force to form torque cross, or the frictional force becomes too high to rotate the rotor 21. Can be prevented. As described above, according to this embodiment, it is possible to prevent the assembly failure of the small motor from occurring.

According to the preload mechanism of this embodiment, the axial dimension L ₁ (FIG. 4) of the middle piece 53, the axial dimension L ₂ (FIG. 5) of the rotor magnet 51a, and the bearing member 6 are used. , 7
Even when there is an error in the mounting dimension of the rotor, it is possible to apply an optimum axial preload to the rotor 21 by adjusting the axial position of the bush 64.

Further, conventionally, the adjustment washer 11 (FIG. 9) was also required inside the bearing member 7, but in the present embodiment, the adjustment washer is not necessary and the structure is simplified.

FIG. 7 is a partially enlarged sectional view of a stepping motor according to the second embodiment of the present invention. As shown in the figure, in the present embodiment, the rotating shaft 5 protruding outward from the bearing member 6 attached to the lid member 33 is provided with a washer 62, a bending washer 8, and a bending washer 8 having the same configuration as in the first embodiment. The washers 62 are sequentially attached, and the bushes 64 are press-fitted from the end portions 63. Further, the washer 62 is attached to the rotating shaft 5 protruding outward from the bearing member 7 attached to the housing 31, and the bush 6 is attached.
Bushing 64 as a biasing force adjusting member having the same configuration as that of No. 4
a is press-fitted. By press-fitting the bush 64a from the end portion 63, the position of the rotor 21 in the arrow X direction is regulated so that the bending washer 8 always applies an appropriate biasing force to the rotor 21.

Therefore, according to the second embodiment, the same effect as that of the first embodiment is obtained, and the members such as the bending washer 8 can be set outside the casing, so that the urging force of the bending washer 8 can be set. It becomes easier to adjust.
Further, since the number of parts inside the casing 2 is reduced, the casing 2 can be made compact in the axial direction.

FIG. 8 is a partially enlarged sectional view of a stepping motor according to the third embodiment of the present invention, which is a modification of the second embodiment. As shown, in this embodiment,
At the center of the lid member 33a of the casing 2a, a cylindrical portion 71 that is recessed inside the casing is formed, and the bearing member 6 is fixed to the end portion 72 of the cylindrical portion 71 on the casing inner side. Then, each member such as the bush 64 is housed in the recess 73 formed by the cylindrical portion 71 and the bearing member 6. That is, from the end 63 of the rotary shaft 5 protruding outward from the bearing member 6, the washer 62, the bending washer 8,
The biasing force of the bending washer 8 is adjusted by sequentially mounting the washers 62 and then press-fitting the bushes 64. As described above, in the present embodiment, members such as the bush 64 do not project outward from the surface of the lid member 33a, so that these members do not interfere. In addition, this embodiment has the same effects as the first and second embodiments.

Although the PM stepping motors have been described in the first to third embodiments, the present invention is not limited to the VR.
Shape (Variable Reluctance Type) and HB shape (Hybrid Typ)
It can also be applied to stepping motors such as e). Further, the present invention can be applied to a rotary small motor other than the stepping motor, for example, a small DC motor of a type having a brush and a commutator or a small AC motor. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0036]

Since the present invention is configured as described above, the position of the rotor in the axial direction can be adjusted after the rotor is installed inside the casing, and the elasticity for preventing the axial vibration of the rotor can be adjusted. The biasing force of the members can be easily adjusted to prevent assembly failure.

[Brief description of drawings]

1 to 6 are views showing a first embodiment of the present invention, and FIG. 1 is a sectional view of a stepping motor.

FIG. 2 is a perspective view showing the external appearance of the stepping motor shown in FIG.

FIG. 3 is a perspective view of the stator core shown in FIG.

4 is a cross-sectional view of the rotor shown in FIG.

FIG. 5 is a sectional view of a rotor having another structure.

6 is a partially enlarged cross-sectional view of FIG.

FIG. 7 is a partially enlarged sectional view of a stepping motor according to a second embodiment of the present invention.

FIG. 8 is a partially enlarged sectional view of a stepping motor according to a third embodiment of the present invention.

9 and 10 are views showing a conventional small motor, and FIG. 9 is a sectional view of a stepping motor.

10 is a partially enlarged cross-sectional view of FIG. 9 and is equivalent to FIG.

[Explanation of symbols]

 2,2a Casing 3 Stator 5 Rotating shaft 6,7 Bearing member 8 Bending washer (elastic member) 20 Stepping motor (small motor) 21,21a Rotor 63 Rotating shaft end 64, 64a Bushing (biasing force adjusting member) C-axis direction

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masao Yagi 280 Ryukoji Temple, Motonomura, Inba-gun, Chiba Mabuchi Motor Co., Ltd. Technical Center

Claims (1)

[Claims] 1. A casing (2, 2a) having a stator (3) mounted therein, and a bearing member arranged in the casing (2, 2a) and provided in the casing (2, 2a). A rotor (21, 2) having a rotating shaft (5) rotatably supported by (6, 7).
1a) and the rotor (21, 21) fitted to the rotating shaft (5).
a) an elastic member (8) for axially urging the rotating shaft (5) from the end (63) of the rotating shaft (5) protruding outward from the bearing members (6, 7). And a biasing force adjusting member (64, 64a) attached to the elastic member (8) for adjusting the biasing force of the elastic member (8).