JPH025644Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a motor for an electric fan or the like that is improved so that lubricating oil leached from an oil-impregnated bearing does not leak out along the rotating shaft.

[Technical background of the invention]

For example, as is well known, the motor for driving the blades of an electric fan is installed in the head of the fan, which is provided with an adjustable tilting angle so that the direction of air blowing can be changed upward or downward. When it is oriented diagonally downward, the rotation axis is tilted in the vertical direction.

[Problems with background technology]

By the way, electric fan motors use oil-impregnated bearings as the rotating shaft bearings, and as the rotation speed of the motor increases to increase the strength of the wind, the amount of lubricating oil leached from the oil-impregnated bearings increases accordingly. If the rotating shaft is tilted, lubricating oil will leak along the rotating shaft, and this will further leak to the outside of the fan head, resulting in a problem that the appearance will be impaired.

[Purpose of invention]

This idea was made in view of the above circumstances.
The purpose is that even if the rotation axis is tilted in the vertical direction,
To provide a motor for an electric fan or the like that is free from the risk of lubricating oil leaking from an oil-impregnated bearing through a rotating shaft.

[Summary of the idea]

In the present invention, a plurality of annular grooves are formed along the axial direction in a part of the rotating shaft that is closer to the shaft tip than the part supported by the oil-impregnated bearing, and the end surface of each annular groove on the shaft tip side is perpendicular to the axis. It is characterized by having a stepped surface.

[Example of idea]

An embodiment in which the present invention is applied to a motor for driving blades of an electric fan will be described below with reference to FIGS. 1 to 4.

In FIG. 1 showing the whole electric fan, 1 is a base, 2 is a fan head which is pivoted to the upper end of the base 1 via a neck piece 3 so that the elevation angle can be adjusted, and a motor 4 is installed inside this fan head 2. A blade 6 is attached to the front end of the rotating shaft 5 of the motor 4. As shown in FIG. 2, the rotating shaft 5 is supported by oil-impregnated bearings 8 (only the rear one is shown) mounted on both the front and rear sides of the motor case 7. As shown in FIG. 3, an annular groove is provided in the vicinity of the supported portion of the rotating shaft 5 by both the front and rear oil-impregnated bearings 8 and on the front and rear end sides of each shaft, as shown in FIG. 9 and 10 (only the rear one is shown) are formed along the axial direction, for example, two in number. The annular grooves 9 and 10 have a tapered shape whose diameter gradually decreases from the oil-impregnated bearing 8 side toward the shaft tip side, and the end faces on the shaft tip side are step surfaces 9a and 10a perpendicular to the axis. in this case,
The inclination angle θ ₁ of the tapered surfaces 9b and 10b of the annular grooves 9 and 10 is the maximum inclination angle θ 2 of the rotating shaft 5 for adjusting the elevation angle of the fan head 2, as shown in FIG _.
The setting is such that gsinθ ₂ cosθ ₁ <r(πN/60) ² sinθ ₁ . However, g is the gravitational acceleration, r is the outer diameter dimension of the rotating shaft 5, and N is the rotating shaft 5.
This is the highest number of revolutions per minute. In addition, in FIGS. 2 and 3, 11 is an oil core provided around the outer periphery of the oil-impregnated bearing 8.

Next, the operation of the above configuration will be explained. When the rotating shaft 5 rotates during air blowing operation, the temperature of the oil-impregnated bearing 8 rises due to frictional heat with the rotating shaft 5, and the lubricating oil in the oil-impregnated bearing 8 expands and leaches out, causing friction between the rotating shaft 5 and the oil-impregnated bearing 8. Supplied between the contact surfaces. Therefore, when the rotational speed of the rotating shaft 5 is increased to increase the strength of the air blowing, the temperature rise of the oil-impregnated bearing 8 due to frictional heat becomes larger.
Accordingly, the amount of lubricating oil leached from the oil-impregnated bearing 8 increases. In this case, it is sufficient that the rotating shaft 5 is in a horizontal state, but if it is tilted as shown in FIG. shall be. At this time, even if the inclination angle of the rotary shaft 5 is the maximum inclination angle θ ₂ , the lubricating oil that is about to flow out along the rotary shaft 5 is first absorbed by the tapered surface 9b of the annular groove 9 on the oil-impregnated bearing 8 side. It comes to be pushed back toward the oil-impregnated bearing 8 side. That is, the descending force F of the lubricating oil that tries to flow toward the shaft tip side through the tapered surface 9b is
The angle it makes with the horizontal line is maximum (θ ₂ + θ ₁ ) and minimum (θ ₂
−θ ₁ ), so F=Mg{sin(θ ₂ +θ ₁ )+sin(θ ₂
−
θ ₁ )}/2=Mgsinθ ₂ cosθ ₁ . However, M is the mass of lubricating oil. On the other hand, the force f by which the lubricating oil is pushed back toward the oil-impregnated bearing 8 side along the tapered surface 9b by centrifugal force is f=Mr(πN/60) ² sinθ ₁ . However, the inclination angle θ ₁ of the inclined surface 9b is expressed as gsinθ ₂ cosθ ₁ <r
(πN/60) ² sin θ Since it is set to a value that satisfies ₁ , F<f and the lubricating oil that tries to flow out along the rotating shaft 5 first flows into the tapered surface of the annular groove 9 on the oil-impregnated bearing 8 side. 9b, it is pushed back toward the oil-impregnated bearing 8 side. Calculating this using specific numerical values, θ ₁ = 38°, r = 0.004 (m), N = 700
(rpm) and set θ ₂ = 24°, then F =
3.14M (Kg), f = 3.30M (Kg), and the pushing back force due to centrifugal force is stronger.

However, if the amount of lubricating oil leached from the oil-impregnated bearing 8 is large, the layer of lubricating oil that adheres around the rotating shaft 5 will become thicker. The oil does not rotate at the same speed as the rotating shaft 5 due to the slip, but rotates at a slower speed than this. Therefore, some of the lubricating oil is pushed back by the tapered surface 9b, but some of the lubricating oil is pushed back by the tapered surface 9b.
and flows toward the tip of the shaft. When this lubricating oil reaches the step surface 9a of the annular groove 9, it flows in the radial direction along the step surface 9a due to centrifugal force, and most of it is scattered from the step surface 9a by the centrifugal force, and the remaining portion The portion further flows along the rotating shaft 5 toward the shaft tip side. Therefore, if only one annular groove 9 were provided, a small amount of lubricating oil would flow down the rotating shaft 5 and drip from the tip of the shaft. Since another annular groove 10 is provided, the lubricating oil passing through the annular groove 9 and attempting to flow further toward the shaft tip side is pushed back by the tapered surface 10b of the annular groove 10 in the same manner as described above. Therefore, it hardly ever actually flows further to the shaft tip side along the tapered surface 10b. Furthermore, even if the lubricating oil were to flow along the tapered surface 10b, the amount of lubricating oil would be so small that it would all be scattered at the stepped surface 10a of the annular groove 10 and would not flow any further toward the shaft tip. .

The above explanation is about the case where the fan head 2 is tilted obliquely upward, but even when the fan head 2 is tilted diagonally downward, the annular grooves formed near the oil-impregnated bearing on the front side, similar to the annular grooves 9 and 10, can be used. The groove prevents lubricating oil from flowing out.

Note that the shapes of the annular grooves 9 and 10 are not limited to those of the above embodiment, but may be of the shapes shown in FIGS. 5 to 7. That is, FIG. 5 shows equal diameter portions 9c, 1 on the shaft tip sides of the tapered surfaces 9b, 10b.
0c, FIG. 6 shows tapered surfaces 9b and 10.
Fig. 7 shows tapered surfaces 9b, 10b and arcuate surfaces 9d, 10d instead of b.
0d is not provided, and the end face on the oil-impregnated bearing 8 side is also made into step surfaces 9e and 10e that are perpendicular to the axis. Further, the number of annular grooves is not limited to two, but may be three or more. Furthermore, the present invention is not limited to electric fan motors, but can be applied to motors of devices that are used tilted in the vertical direction.

[Effect of idea]

As explained above, in the present invention, even if the lubricating oil that has oozed out from the oil-impregnated bearing tries to flow out to the tip of the shaft through the vertically inclined rotating shaft, the lubricating oil will flow through the plurality of holes formed on the rotating shaft. Since the lubricating oil is returned to the oil-containing bearing side and scattered outward by the annular grooves, problems such as leakage of the lubricating oil along the rotating shaft can be prevented.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the present invention,
Fig. 1 is a side view of the electric fan, Fig. 2 is a partially cutaway side view of the motor, Fig. 3 is an enlarged longitudinal sectional side view of the main parts, Fig. 4 is an explanatory diagram of the operation, and Fig. 5 to FIG. 7 is a schematic diagram of main parts showing other different embodiments of the present invention. In the figure, 4 is a motor, 5 is a rotating shaft, 8 is an oil-impregnated bearing, 9 and 10 are annular grooves, and 9a and 10a are stepped surfaces.

Claims (1)

[Scope of utility model registration request] In a motor such as an electric fan, which has a rotating shaft supported by an oil-impregnated bearing and is used tilted vertically for changing the direction of air blowing, etc., the shaft tip side of the rotating shaft is supported by the oil-impregnated bearing. A motor for an electric fan or the like, characterized in that a plurality of annular grooves are formed along the axial direction in a section, and the end surface of each annular groove on the shaft tip side is a stepped surface perpendicular to the axis.