JPH0265636A - Structure for securing rotor and output shaft of radial type synchronous motor - Google Patents

Abstract

PURPOSE:To prevent bending of output shaft by fitting the rotor of a synchronous motor, arranged alternately in the circumferential direction with rotor cores and magnets, to the threaded output shaft then filling the gap between the rotor and the thread with molding resin. CONSTITUTION:Rotor cores 14 and magnets 16 are arranged alternately in the circumferential direction to form the rotor 12 of a synchronous motor, then the rotor 12 is contained a tubular jig 30. The rotary shaft 10 of the motor is threaded 11 and inserted into the central hole of the rotor 12. Resin 24 is filled in the gap between the rotary shaft 10 and the inner circumferential face of the rotor 12 and molded. By such arrangement, bending of the output shaft can be prevented easily and torque is transmitted reliably from the rotor 12 to the rotary shaft. This structure is preferably employed in a motor having long rotary shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a structure for fixing a so-called radial type rotor to an output shaft, in which rotor cores and magnets are arranged alternately in parallel in the circumferential direction.

[Conventional technology]

In order to fix the radial type rotor to the output shaft in -a, end plates are attached to both ends of the rotor, and the rotor is fixed to the output shaft via the end plates. One of the methods is shrink fitting, and there is also a method of fastening and fixing by driving a pin member. Furthermore, in order to prevent the relative looseness of the rotor core, magnets, etc. that constitute the rotor, the rotor is often treated with an impregnating material.

[Problem to be solved by the invention]

However, in both the above-mentioned shrink fit method and the method using a bottle member, the parts other than the end of the rotor have a gap with the output shaft.
Therefore, if the output shaft is subjected to a bending action due to some external force, the output shaft will be bent inside the rotor. In addition, particularly when fixing a rotor for high output torque that is long in the axial direction, the above-mentioned shrink fitting method cannot provide a highly reliable fastening. Of course, when rotors have the same cross-sectional shape but different axial lengths, the longer rotor has a larger output torque, but the shrink-fit portion that transmits that torque is 0;
This is because it is limited to two locations after 5.

Therefore, in order to solve these problems, the present invention aims to provide a fixing structure between a rotor and an output shaft, which prevents the output shaft from bending and provides highly reliable fastening.

[Means to solve the problem]

In view of the above objects, the present invention provides a structure in which a rotor core and magnets are fixed to an output shaft of a rotor of a synchronous electric motor of a type in which rotor cores and magnets are arranged alternately in parallel in the circumferential direction. The rotor is inserted into the output shaft over a region including the threaded portion, and a gap between the region including the threaded portion and the inner peripheral surface of the rotor is filled with molding resin. Provides a fixing structure between a radial type synchronous motor rotor and an output shaft.

[For production]

The inner peripheral surface of the rotor has a generally polygonal shape due to the structure of a radial type rotor, and the surface of the output shaft facing the inner peripheral surface of the rotor has a thread that can be easily formed using a lathe. Since the portions are formed, it is possible to reliably transmit torque without causing the rotor or output shaft and the molding resin filled in the gap between them to slip. Furthermore, due to the presence of the filled molding resin, even if some kind of bending action is applied to the output shaft, it will not actually bend.

〔Example〕

The present invention will be described in more detail below based on embodiments shown in the accompanying drawings.

The output shaft 10 includes a so-called radial type rotor 12 in which magnets 14 and rotor cores 16 are arranged alternately in parallel in the circumferential direction.
The method and structure for fixing it will be explained below. In this embodiment, the rotors 12 are four unit rotors 12a each having a predetermined length in the axial direction.

12b, 12C, and 12d are arranged in parallel in the axial direction. In order to integrate the magnet 14 and the rotor core 16, a tlJm material 18 is inserted through the rotor core 6. In this way, four unit rotors 12a, 12b
, 12c, and 12d is fixed to the output shaft 10, but a gap exists between the inner peripheral surface of the rotor 12 and the output shaft 10. End plates 26 are provided at both ends of the rotor 12, and the inner circumferential portion thereof is set to a size that allows it to be lightly press-fitted into the output shaft 10. The rotor 12 with the end plates 26 provided at both ends is press-fitted onto the output shaft 10 with a small force and stopped at a predetermined axial position. The output shaft at this predetermined position is provided with a groove 32 having an inlet 28 located outside the inner circumference of one end Fi, 26. This groove 32 allows molding resin, such as epoxy resin, to flow into the gap between the rotor 12 and the output shaft 10 (in some cases, it may be press-fitted).
This is a resin liquid introduction groove for filling the gap with molding resin.

The molding resin 24 is injected from the injection port 28 to fill the gap between the rotor 12 and the output shaft 10, and when the injection is continued, it overflows onto the surface of the rotor I20 from the gap between the magnet 14 and the rotor core I6.

If the resin 24 is simply injected, the resin 22' overflowing onto the surface of the rotor 12 will partially swell as shown in FIG. As is well known (there is only a small gap between the rotor and the stator, the above-mentioned swollen resin must not swell beyond the maximum outer diameter of the rotor. To prevent this, for example, as shown in Fig. 3) If a cylindrical jig case 30 is placed over the outside of the rotor 12 as shown, the overflowing resin 22 will be contained within the maximum outer diameter of the rotor 12 as shown in FIG. Although the resin filled between the rotor 10 and the shaft 10 is not visible from the outside, it can be confirmed that the internal gap is filled with resin due to the presence of resin overflowing onto the surface of the rotor 12.

As the output shaft load used in this structure is zero, a threaded portion 11 as shown in FIG.
When formed using a lathe, the filled molded resin 24 and the threaded portion 11 engage with each other, and the rotor 1
2. It becomes possible to reliably transmit the torque generated in 2. On the other hand, as can be seen from FIG. 2, since the inner circumferential surface of the rotor 12 has a generally polygonal shape, the rotor 12 and the filled mold resin 24 do not slip against each other.

Considering only the reliable transmission of torque, a spline having grooves in the axial direction is optimal, but in that case, relative slippage may occur in the axial direction between the output shaft 10 and the filled molding resin 24. There is sex. Therefore, it is most preferable to provide a spiral groove like a screw, and unlike the case of forming a spline, it can be processed using an easily available lathe, and the output shaft can be manufactured efficiently and at low cost. . Since the purpose is to suppress relative slippage with the filled mold resin 24, as shown in FIG. 6, the surface of the output shaft lO' is roughly machined using a lathe instead of the screw 11 in FIG. (Includes screws in a broad sense.)
It is also possible to have a

Further, the pitch of the helical groove (thread 1111') shown in FIGS. 5 and 6 may be large, and in this case, it may be a multi-start thread instead of a single thread.

It is conceivable that a row left machining is applied to a part having the same effect as the rough machining section 11' shown in Fig. 6 above, but since the knurling machining is a process in which the tool is strongly pressed against the workpiece (output shaft). , the output shaft tends to warp, making it particularly unsuitable for elongated output shafts. In addition, in order to transmit torque, chamfering the outer peripheral surface of the output shaft in the longitudinal direction or providing a keyway in the longitudinal direction may be considered, but like the spline described above, it cannot be machined with a lathe and is costly. Becomes high.

Figure 7 shows the maximum transmitted torque, expressed as a percentage, according to experiments, for a rotor using the output shaft 10 having the threaded portion 11 shown in Figure 5 and a rotor using a normal cylindrical output shaft. be. The horizontal axis shows the ambient temperature of the rotor, and the vertical axis shows the maximum torque transmitted by the rotor using a normal cylindrical output shaft at room temperature, expressed as 100%.

- The change curve 38 shown by the dotted chain line is for the case of a cylindrical output shaft, and the straight line 40 shown by the solid line is for the case according to the structure of the present invention. As is clear from the figure, at room temperature, epoxy resin is in a hardened state, so there is no difference between the two, but at high temperatures, epoxy resin tends to soften, and curve 38 shows a significant drop in torque transmission performance. However, in the case of the present invention, no decrease is observed.

C Effects of the Invention] As is clear from the above description, according to the present invention, an output shaft having a threaded portion that can be easily formed with a lathe is used,
The torque generated on the rotor is reliably transmitted to the output shaft, and the output shaft is not bent due to the presence of the filled mold resin.

[Brief explanation of the drawing]

Fig. 1 is a front view of the rotor and output shaft fixedly coupled according to the present invention, Fig. 2 is a partially enlarged cross-sectional view taken along the arrow line nn in Fig. 1, and Fig. 3 is the fixation of the present invention. FIG. 4 is a partial cross-sectional view showing a process of manufacturing the structure; FIG. 4 is a partial cross-sectional view of a rotor with an output shaft produced by a manufacturing method different from that shown in FIG. 3; FIG. One embodiment of the output shaft, FIG. 6 is a second embodiment replacing FIG. 5, and FIG. 7 is a graph showing the effects of the present invention. 10... Output shaft, u, tr... Threaded part, 12
...Rotor, 14...McNet, 16.
...Rotor core, 22.22', 24...Molded resin, 28.
... Inlet, 30 ... Cylindrical jig case, 3
2... Groove.

Claims (1)

[Claims] 1. A structure in which the rotor of a synchronous electric motor of a type in which rotor cores and magnets are arranged alternately in the circumferential direction is fixed to an output shaft, and the output shaft has a threaded portion on the surface, and the rotor is fixed to the output shaft. A radial type synchronous motor rotor and an output, characterized in that the rotor is inserted into the output shaft over a region including the screw portion, and a gap between the region including the screw portion and the inner peripheral surface of the rotor is filled with molding resin. Fixed structure with shaft.