JPH019248Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement in the configuration of a bladed welded structure shaft of an armature of a rotating electric machine.

The bladed welded structure shaft that constitutes the armature of a rotating electric machine has a ventilation hole in the axial direction in order to achieve cooling ventilation effects, lower inertia, and weight reduction of the armature. A conventional configuration will be described with reference to FIG. 1 (the right side of the figure is the output side in the case of an electric motor) and FIG. 2. In both figures, 1 is a shaft, 2 is a blade, and 3 is an iron core. A plurality of blades 2 are attached to the shaft 1 by fillet welding in the radial direction, and the iron core 3 is fitted on the outer periphery of the shaft 1. In both figures, for convenience of explanation, the state in which the iron core 3 is removed is shown. In the above configuration, the tangential force T due to the torque acting on the outer periphery of the iron core 3 is transmitted to the shaft 1 via the blades 2.

By the way, as mentioned above, the tangential force T is
As a weak point in strength in the structure that transmits
It is mainly the toe of the welded bead that cracks due to fatigue due to repeated stress. As an example of this, Fig. 3 shows a crack D from the blade side toe C of the bead B where the shaft 1 and the blade 2 are welded.
This shows the case where this occurs.

Next, we will examine the locations that pose problems from the perspective of fatigue strength. The bending deformation that the blade 2 undergoes due to the tangential force T acting on the outer periphery of the iron core 3 is as follows:
It undergoes bending deformation as shown by the broken line in FIG. The problem is that this bending deformation is not uniform along the axial direction, but is greatest at the blade ends. This situation will be briefly explained with reference to FIGS. 4 and 5. In both figures, the number of blades is two, the outer periphery of blade 2 is fixed, and the bending deformation of the blade when shaft 1 receives torque T ₁ is simulated. The shaft 1 is twisted through a certain angle by being subjected to a torque T ₁ , which causes the blade to undergo a bending deformation as shown by the dashed line. At this time, since the shaft is torsionally deformed, as the axial dimension of the blade 2 increases, it becomes difficult for torque to be transmitted to the blade end 4 on the anti-torque side. As shown in FIG. 6, as an example of the results of an analysis using the finite element method of the bending stress at the blade-side toe 5 of a welded shaft with blades that receives a tangential force T on the outer periphery of the iron core 3, FIG. The curve shown in was obtained. That is, in FIG. 7, the horizontal axis represents the blade side toe 5.
The vertical axis shows the bending stress ratio when the average value is set to 1, and the axial position l from the blade end is taken as the vertical axis. According to this result, the axial distribution of bending stress is not uniform;
A tendency to concentrate toward the blade tip was observed, and the maximum value was about three times the average value.
It can be seen that this structural stress concentration is quite detrimental to the fatigue strength at the vane side toe.

As mentioned above, it has been found that the location that poses a problem in terms of fatigue strength is at the blade end, so the above-mentioned conventional example will be discussed in this regard. In FIGS. 1 and 2, 6 is the output side end of the blade 2, 7
8 is the circumferential bead where the blade end 6 and the shaft 1 are welded, 8 is the shaft side toe of the bead 7, 9 is the longitudinal bead where the blade 2 and the shaft 1 are welded, and 10 is the blade side stop of the bead 9. Assuming that the end portion 11a is the unwelded part that remains when the blade 2 and the shaft 1 are welded, and 11b is the tip of the unwelded part, from the viewpoint of fatigue strength as described above. It is thought that the problematic positions are mainly the shaft-side toe 8 of the circumferential bead 7 of the blade end 6, the blade-side toe 10 of the longitudinal bead 9, and the unwelded portion tip 11b.

The main purpose of the present invention is to improve the fatigue strength of the blade toe 10 of the longitudinal bead 9 by adopting a configuration that alleviates the structural stress concentration at the blade end. In addition, when the unwelded part 11a between the blade 2 and the shaft 1 remains, the purpose is also to improve the fatigue strength of the unwelded part tip 11b.

An embodiment illustrating the present invention will be described below.

In Figures 8 and 9, 1 to 3, 6, 9,
Reference numerals 10 and 11 indicate members that are the same as or equivalent to those shown in FIGS. 1 and 2.

In the present invention, in the conventional configuration, the shaft 1 is made into a conical shape near the blade end 6 where the bending stress of the blade 2 increases, and correspondingly, the height h of the blade 2 also becomes smaller toward the blade end 6. This is the configuration.

Torque transmission according to this embodiment is performed in the same manner as in the conventional example. However, in this embodiment, the bending stress of the blade 2 near the blade end 6 is reduced compared to that of the conventional configuration because the height h of the blade 2 is small.

As described above, in the bladed welded structure shaft of the rotary electric machine armature according to the present invention, the bending stress of the blade 2 in the vicinity of the blade end 6 is smaller than that of the conventional structure, so that the blade side toe 10 and This has an extremely excellent effect of improving the fatigue strength at the tip 11b of the unwelded portion.

[Brief explanation of the drawing]

Figures 1 and 2 show the configuration of a conventional bladed welded shaft with the iron core removed.
The figure is a front view, and FIG. 2 is a cross-sectional side view taken along line A-A' in FIG. Figure 3 is a cross-sectional side view showing a state in which a crack has occurred at the toe of the blade, and Figures 4 and 5 are simulations of the bending deformation that the blade undergoes when the shaft receives torque. Figure 4 is a perspective view;
FIG. 5 is a side view. Figure 6 is a perspective view for analyzing the bending stress at the blade-side toe of a welded shaft with blades that receives a tangential force T on the outer periphery of the iron core, and Figure 7 is a perspective view for analyzing the bending stress at the blade-side toe of a shaft that receives a tangential force T on the outer periphery of the iron core. The bending stress ratio curve diagrams, FIGS. 8 and 9, shown in FIG. 8 show an embodiment of the present invention. FIG. 8 is a front view, and FIG. FIG. 3 is a side view showing the right half. 1...shaft, 2...blade, 6...blade end,
h...Height of the blade.

Claims (1)

[Scope of utility model registration request] In the vicinity of the blade end 6, the shaft 1 is made into a conical shape, and the height h of the blade 2 is correspondingly set to the blade end 6.
A bladed welded structure shaft for an armature of a rotating electric machine, characterized in that the shaft gradually becomes smaller as it approaches.