JPH0135584Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to an improvement in the assembly structure of a small synchronous motor with a reduction gear.

Prior Art As a conventional small synchronous motor 1, those shown in FIGS. 1 to 3 are known.

First, the one shown in FIG. 1 includes a cup-shaped motor unit 7 which houses an excitation coil 12, a rotor 4, and a core 6 with a second magnetic pole 5 in a motor case 3 in which the first magnetic pole 2 is bent. A gear train unit 11 in which a lid case 9 is fitted into a gear case 8 and a gear train 10 that meshes with the rotor 4 is incorporated therein.
The electric motor unit 7 and the wheel train unit 11 are integrated by overlapping them.

However, in the above-mentioned electric motor, the two electric motor units 7 and the gear train unit 11 are overlapped and combined, so the thickness of the electric motor is increased, and the motor case 3 and gear case 8 are assembled separately, so the number of parts is reduced. This has the added benefit of increasing.

Next, in the motor shown in FIG. 2, a gear train unit 11, which forms a second magnetic pole 5 with a part of the core 6, is press-fitted into a motor case 3 that houses a rotor 4 and an excitation coil 12. That's what happens. In this example, gear case 8 also serves as core 6, so
The number of parts can be reduced and the motor can be made thinner.

However, in the above configuration, the entire circumferential wall of the core 6, which also serves as the gear case 8, is press-fitted into the inner circumferential surface of the motor case 3.
And the motor case 3 is deformed, and the hole of the bearing shaft of the gear train 10 is misaligned.
There is a problem that meshing noise occurs at zero.

The motor case 3 in which the rotor 4 and the excitation coil 12 are housed is shown in FIG.
The core 6 with the support shaft 16 implanted therein is press-fitted, the gear train 10 is then assembled, and the lid case 9 is fixed to the motor case 3 by caulking or the like.
In order to prevent deformation of the core 6, the outer periphery of the core 6 is normally drawn, and the entire outer periphery of the core 6 is a press-fit surface.

However, in this conventional example, since the drawing process is performed to prevent deformation of the core 6, an axial misalignment occurs between the second magnetic pole 5 formed on the core 6 and the outer periphery, which deteriorates the rotational characteristics of the rotor 4. There is a problem with doing so. On the other hand, since a drawing die must be prepared for the drawing process, there is a problem in that manufacturing costs increase. Furthermore, the motor case 3 is easily deformed when the core 6 is press-fitted, and when positioning the core 6 in the rotational direction using an assembly jig, the accuracy of the fit between the support shaft 16 and the lid case 9 deteriorates, causing meshing noise in the gear train 10. There is a problem that occurs. Furthermore, since the height of the storage part of the gear train 10, that is, the distance between the core 6 and the lid case 9, is determined by a press-fitting jig, there is a large variation in each process, and the height of the gear in the axial direction is larger than necessary. Rotor 4 when it is hot or when it is less
A stoppage phenomenon occurs.

Purpose of the invention Therefore, the purpose of the present invention is to achieve a reduction in the thickness of this type of small synchronous motor, maintain the accuracy of the bearing shaft of the gear train and its hole position, and maintain the accuracy of the motor case, core and lid. An object of the present invention is to provide a small synchronous motor that can accurately ensure the mutual position of cases.

Summary of the invention Therefore, the present invention uses the gear case of the gear train unit as the core, provides a plurality of pillars around the outer periphery of this core, inserts the outer periphery of the pillars into the motor case as a press-fit surface, and is formed as a reference surface that regulates the height of the lid case and the core to be constant. Therefore, when assembling the wheel train unit into the motor case, the entire circumference of the core is not press-fitted into the motor case, and the plurality of struts are easily inserted in a light press-fit state. This prevents abnormal deformation of the motor case and core.
The support shaft of the gear train and the positional accuracy of its hole can be maintained with high precision.

In addition, since the struts are formed at the above-mentioned reference height, an appropriate axial spacing can be set for the gear train when the core and the lid case are engaged, which prevents rotor whirring and meshing noise. Never.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of the present invention will be specifically described below based on an embodiment shown in the drawings.

The configuration of the small synchronous motor 1 of the present invention is shown in FIGS. 4 and 5. In FIG. 4, a rotor 4 and an excitation coil 12 are housed in a cup-shaped motor case 3 as in the conventional example, and four coils are placed facing the outer periphery of the rotor 4 from the bottom wall of the motor case 3. The first magnetic pole 2 is bent.

On the other hand, the core 6 is composed of a core substrate 13 having a substantially donut shape, and four second magnetic poles 5 bent downward from the inner circumference and upward from the outer circumference of the core substrate 13. It has a plurality of pillars 14, for example, two pillars 14, which are erected. The upper end of the support column 14 is formed into a convex shape, and the shoulder of this convex shape is formed as a reference surface 15 having a predetermined height. Further, an appropriate number of support shafts 16 are implanted at desired positions on the core substrate 13, and a plurality of gears 17 are rotatably fitted onto the support shafts 16 to form a gear train 10.

On the other hand, the lid case 9 has a recess 18 into which the protrusion 14a of the support column 14 engages, a support hole 19 that supports the support shaft 16 and the rotor shaft of the rotor 4, and a bearing hole 21 through which the motor output shaft 20 projects. It is provided.

With the gear 17 fitted into the support shaft 16, the lid case 9 is engaged with the protrusion 14a of the column 14 through its recess 18, and the lid case 9 and the column 14 are fixed in position. ing. At this time, the tip of the support shaft 16 fits into the support hole 19. Therefore, the combined body of the core 6 and the lid case 9 accommodates therein the gear train 10 that meshes with the rotor 4 by means of the bearing shaft 16, and forms the gear train unit 1.
form 1. In addition, in this case, the pillar 1
The height of the reference plane 15 of No. 4, that is, the interval when the core substrate 13 and the lid case 9 are combined, is regulated to an optimum distance for the configuration of the wheel train unit 11.

action of invention Next, the operation of the above embodiment will be explained.

In the present invention, the combined body of the core 6 and the lid case 9 incorporates the gear train 10 therein to constitute the wheel train unit 11, and as a result, the work of assembling the wheel train unit 11 into the motor case 3 is extremely easy. be. And in its built-in state, core 6
Since it also serves as a gear case, it can be made thinner accordingly. Furthermore, since the peripheral wall of the gear train unit 11 is not continuous over the entire circumference, but is made up of a plurality of supports 14, it is difficult to insert the gear train unit 11 into the motor case 3. Therefore, large pressure is not applied to both the motor case 3 and the wheel train unit 11, and the insertion is performed with light pressure, thereby preventing abnormal deformation of the motor case 3 and the core 6. Therefore, the mutual positional accuracy of the support shaft 16 and its support hole 19 can be maintained with high precision, and misalignment of the axis of the second magnetic pole 5 can also be prevented. Furthermore, since the height of the reference plane 15 of the support column 14, that is, the combination distance between the lid case 9 and the core board 13, is regulated to an optimal constant value, the play in the axial direction of the gear 17 can be ensured at an optimal value. The gears mesh extremely smoothly without any gear noise.

Modified Example of the Invention In the above embodiment, an example was shown in which two pillars 14 were provided at opposing positions, but it is also possible to configure with more pillars 14.

Further, in the above embodiment, the engaging portion of the support column 14 is formed as the protrusion 14, and the engaging portion of the lid case 9 is formed as the recessed portion 18, but they may be formed in the opposite manner. Furthermore, the reference surface 15 of the support column 14 may not be formed into a projecting shape, but may be formed into a flat shape.

Effects of the Invention As described above, in the present invention, the core is also used as the gear case, so the number of parts is reduced, and the manufacturing cost and thickness of the small synchronous motor can be reduced.

In addition, since the gear train unit and motor case can be fitted only on a part of the outer periphery of the core and with light pressure, abnormal deformation of the motor case and lid case is avoided and the gear train is supported. The positional accuracy of the shaft and its hole can be maintained with high precision.

Furthermore, the height of the gear accommodating section, that is, the distance between the core board and the lid case, is regulated by the height of the reference plane of the support column, and is not affected by assembly jigs, etc., and can be secured by managing the core parts, making assembly easier. This makes it easier to assemble the product, and reduces product variations during the assembly process.

[Brief explanation of the drawing]

Figures 1 to 3 are elevational views showing a cross section of the main parts of a conventional small synchronous motor, Figure 4 is an elevational view showing a cross section of the main parts of a small synchronous motor according to the present invention, and Figure 5 is an elevational view showing a cross section of the main parts of a small synchronous motor according to the present invention. FIG. 2 is an exploded assembly diagram of a gear train unit of an electric motor. 1... Small synchronous motor, 2... First magnetic pole, 3
... Motor case, 5 ... Second magnetic pole, 6 ... Core, 9 ... Lid case, 11 ... Gear train unit, 1
2... Excitation coil, 13... Core board, 14...
Support column, 15... Reference plane, 20... Output shaft.

Claims (1)

[Scope of utility model registration request] A cup-shaped motor case in which a first magnetic pole facing the rotor is formed, a second magnetic pole facing the rotor is formed in the inner peripheral part of the donut-shaped core board, and a second magnetic pole facing the rotor is formed in the outer peripheral part of the core board. has a core each provided with a plurality of pillars that are lightly press-fitted into the motor case, and a lid case that engages with the pillars; The combined core and lid case form a gear train that is housed inside the motor case and meshes with the rotor and output shaft. A small synchronous motor characterized by: