Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-03-02
2003-12-16
Le, Dang (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C074S573110, C369S263100
Reexamination Certificate
active
06664670
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an automatic balancing apparatus and a motor with a function to cancel rotational unbalances of a rotary body.
2. Description of Related Art
Automatic balancing apparatuses are often implemented in various rotary driving apparatuses that are used in industrial machines, home electric appliances, computers and the like. An automatic balancing apparatus is employed in a rotary body such as a rotary driving apparatus including a rotor shaft to cancel out rotational unbalances of the rotary body. Japanese laid-open patent applications HEI 10-257710 and HEI 11-178272 describe such automatic balancing apparatuses.
For example, Japanese laid-open patent application HEI 10-257710 describes a balancing member
3
provided about a rotor shaft of a motor
1
, as shown in FIG.
12
. The balancing member
3
is formed from a disc-like case body having an internal space provided therein. Plural ball members
4
are movably disposed within the space of the balancing member
3
. When the rotational speed of the motor
1
exceeds its resonant rotational speed CR, the ball members
4
start moving in an opposite direction with respect to the position of center of gravity of a rotator body that includes the rotor shaft
2
and the balancing member
3
, to thereby balance the rotator body. As a result, vibrations of the rotator body are reduced and the rotation thereof is stabilized.
However, in the automatic balancing apparatus described above, the plural ball members
4
tend to become unstable when the rotational speed of the motor
1
is below the resonant rotational speed CR, such that the ball members
4
collide against one another and make colliding noises and may be damaged. Moreover, the contact resistance among the ball members
4
becomes large at high-speed rotations when the viscosity of flowing air increases. As a result, the ball members
4
cannot be accurately disposed at appropriate balancing positions, and thus the rotary body cannot be sufficiently stabilized.
An automatic balancing apparatus described in Japanese laid-open patent application HEI 11-178272 has fan-shaped balancing members
5
rotatably disposed about a rotor shaft
6
, as shown in FIG.
13
. The automatic balancing apparatus described in Japanese laid-open patent application HEI 11-178272 generally solves the problems described above.
However, in the automatic balancing apparatus of the Japanese laid-open patent application HEI 11-178272, each of the balancing members
5
has a generally fan-like shape as viewed in plan, and therefore has to be made relatively large. This results in a problem in that the overall size of the automatic balancing apparatus becomes large.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an automatic balancing apparatus having a smaller and simplified structure that achieves an optimum balance correction action of balancing members.
It is another object of the present invention to provide an automatic balancing apparatus that has an improved rotational stability particularly at a low rotational speed range.
In accordance with one embodiment of the present invention, an automatic balancing apparatus may have a plurality of balancing members rotatable about the axis of rotation, each of the balancing members having a balance action section spaced a specified distance in a radial direction from the axis of rotation and a connection section that rotatably couples the balance action section to the axis of rotation. The balance action section has a mass that effects a balance correction action, and the connection section has a mass that substantially does not affect the balance correction action compared to the balance action section.
By the embodiment of the present invention having the structure described above, the center of gravity of each of the balancing members is shifted more outwardly from the rotor shaft in the radial direction compared to the conventional automatic balancing apparatus having fan-shaped balancing members, such as the one described in Japanese laid-open patent application HEI 11-178272. As a result, a smaller sized automatic balancing apparatus can achieve a better balance correction action.
In accordance with one embodiment of the present invention, the balance action section may have a balance storage section having an outer abutting surface and a balancing mass freely moveable in the balance storage section. The abutting surface may be in an arcuate form. The balancing mass is supported by the abutting surface when a rotator body on which the automatic balancing apparatus is mounted is operated at speeds that exceed a resonant rotational speed CR of the rotator body. As a result, the center of gravity of the balancing member is further shifted outwardly in the radial direction, and therefore a further miniaturization can be achieved.
The balancing mass may be formed from a globular body such as a ball that can readily move in response to a rotational unbalance. As a result, the sensitivity in the balance correction action can be increased. Also, each of the balancing members may be provided with a single globular body, such that the globular bodies are disposed isolated from one another. Accordingly, there is no collision between the globular bodies, and therefore generation of noises and damages to the globular bodies can be securely prevented.
In accordance with one embodiment of the present invention, the balance storage section has a retaining recessed section that retains the balancing mass in a region closer to the axis of rotation than the outer abutting surface in a low rotational speed range below the resonant rotational speed CR. The retaining recessed section may be provided with a step difference having a height in which the balancing mass can move out of the step difference of the retaining recessed section by a centrifugal force generated when the rotator body rotates at a speed exceeding the resonant rotational speed CR thereof. As a result, when the rotator body rotates in a low rotational speed range below the resonant rotational speed CR thereof, the balancing mass is retained in the retaining recessed section in a balanced state. As a result, when the rotator body starts its rotational operation again or in the low rotational speed range, the rotator body stably rotates in the balanced state.
In accordance with one embodiment of the present invention, the balancing mass may be formed from liquid that can freely change its configuration. As a result, the balance storage section can also be changed to any appropriate shape, which improves the degree of freedom in designs.
In accordance with one embodiment of the present invention, the balance action section may be formed from a solid metal weight that is attached to an outer end section of the connection section that extends in the radial direction. As a result, the center of gravity of the balancing member is further shifted outwardly in the radial direction by the metal weight, and therefore a further miniaturization can be achieved.
In accordance with one embodiment of the present invention, an automatic balancing apparatus may have a plurality of balancing members rotatable about the axis of rotation, each of the balancing members having a circular main body rotatable about the axis of rotation and an unbalance section that is formed by removing a portion of the circular main body.
As a result, a mass required for a balance correction action can be effectively secured along an entire peripheral region of the circular main body section. As a result, the automatic balancing apparatus of the present invention can be reduced in size and thickness for a given mass, compared to the conventional apparatus having fan-shaped balancing members having the same mass. Accordingly, the entire structure of the apparatus can be reduced in size and thickness.
By the use of the circular main body, an extreme cantilever structure of the conventional apparatus can be eliminated, and therefore
Higuchi Daisuke
Kikuchi Yoshimi
Hogan & Hartson LLP
Le Dang
Sankyo Seiki Mfg. Co. Ltd.
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