News Column

Patent Application Titled "Vibration Control Device and Control Method Therefor" Published Online

September 3, 2014



By a News Reporter-Staff News Editor at Journal of Engineering -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Yoshitake, Yutaka (Nagasaki-shi, JP); Kajiwara, Shuhei (Tamano-shi, JP), filed on May 16, 2012, was made available online on August 21, 2014.

The assignee for this patent application is Mitsui Engineering & Shipbuilding Co., Ltd.

Reporters obtained the following quote from the background information supplied by the inventors: "A rotary machine such as a hard disk of a personal computer, an electric fan, a cutting device, and a power generation turbine is preferably designed with its imbalance as small as possible, and careful balancing is performed before shipment. However, since there is a limit to balancing of the rotary machine, an external force of a centrifugal force type is generated during an operation, and vibration occurs. Furthermore, there are also machines which inevitably generate large imbalance during its operation due to its performances as in the case of an electric washing machine and reciprocating machines which inevitably generate vibration to some degree due to its structure as in the case of an engine. In order to suppress vibration of these machines (hereinafter referred to as a vibrating body), an automatic balancer and a vibration compensator are proposed (see Patent Literature 1, for example).

"FIG. 8 illustrates an example of an automatic balancer 1X. This automatic balancer 1X has a circumferential passage 30 having the same central axis as that of a rotary machine 32 (a centrifugal separator and the like, for example) and a balance modifier 31 movably arranged in the passage 30. Here, outline arrows indicate vibration direction Z of the rotary machine 32.

"Subsequently, an operation of the automatic balancer 1X will be described. This automatic balancer 1X can suppress vibration of the rotary machine 32 by passive movement of the balance modifier 31 in the rotating passage 30 and relative standstill in the passage 30 when vibration occurs in the rotary machine 32. At this time, a position where the balance modifier 31 relatively stands still after it moves in the passage 30 is passively changed depending on an amplitude and a vibration frequency of the rotary machine 32.

"On the other hand, the vibration compensator has a vibration detection sensor for detecting vibration of a machine such as a diesel engine and the like, a plurality of rotatable mass bodies arranged at appropriate positions in the machine, and a motor for changing a rotational speed or phase of each of the mass bodies. This vibration compensator can suppress vibration of the machine, by detecting vibration of the machine by the vibration detection sensor, by sending a control signal to each of the motors, and by changing the rotational speed or phase of each of the mass bodies.

"However, the above-mentioned automatic balancer and the vibration compensator have some problems. First, the automatic balancer has a problem in which it amplifies an amplitude of the machine in a region with a vibration frequency (frequency) lower than a resonant frequency (or a resonance point).

"Second, the automatic balancer has a problem in which self-excited vibration is generated in a region of a vibration frequency higher than the resonance point. That is, although the automatic balancer has a function of automatically suppressing vibration, the balance modifier and the like cannot be positively controlled, and thus vibration of the machine might be amplified in some cases.

"Third, the vibration compensator requires a precise motor or a complicated control mechanism, and thus has a problem of a high cost."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "Technical Problem

"The present invention has been made in view of the above-mentioned problems and has an object to provide a vibration control device which can automatically suppress vibration of the vibrating body without installing a vibration detection sensor on a vibrating body such as a rotary machine, a reciprocating machine or the like, or the vibration control device, or without controlling a rotational speed or phase of the vibration control device. Furthermore, an object of the present invention is to provide a low-cost vibration control device.

"Solution to Problem

"In order to achieve the above-mentioned object, a vibration control device according to the present invention, installed in a vibrating body and controlling vibration of the vibrating body includes a rotating shaft, a mass body fixed to the rotating shaft, and an activation apparatus which adds power of a rotational motion around the rotating shaft to the mass body.

"With this configuration, the vibration control device can automatically suppress vibration of the vibrating body without control of a rotational speed or phase. This vibration control device can automatically suppress vibration of the vibrating body by executing control of adding an initial velocity to the mass body only at start-up.

"In the above-mentioned vibration control device, the vibration control device has at least the two mass bodies which can rotate independently of each other and having a structure in which relative positions of the mass bodies in a rotating direction are automatically adjusted. With this configuration, the mass body of the vibration control device has its relative positional relationship automatically adjusted so as to be optimal for vibration control in accordance with an amplitude amount and frequency characteristics of the vibrating body. As a result, a vibration control performance of the vibration control device is largely enhanced.

"In the above-mentioned vibration control device, the vibration control device has a power assist mechanism for offsetting rotation resistance of the mass body, the power assist mechanism having a power source for adding the power to the rotating shaft or the mass body and a control device, the control device having a reading mechanism for detecting a vibration frequency of the vibrating body, a control map for determining the power the power source should add to the rotating shaft or the mass body from the vibration frequency of the vibrating body and an output control mechanism for outputting the determined power to the rotating shaft or the mass body from the power source.

"With this configuration, not only can a rotation period of the mass body in the vibration control device be synchronized with a vibration period of the vibrating body without a delay, but also the mass body can be rotated with an optimal phase, and the vibration control performance can be enhanced. This is because rotation resistance of the mass body can be offset by the power assist mechanism.

"A control method for the vibration control device according to the present invention in order to achieve the above-mentioned object is a control method for a vibration control device installed in a vibrating body and controlling vibration of the vibrating body and having a rotating shaft, a mass body fixed to the rotating shaft, an activation apparatus for adding power of a rotational motion around the rotating shaft to the mass body, and a power assist mechanism for offsetting rotation resistance of the mass body, the method including a reading step of reading a vibration frequency of the vibrating body by the power assist mechanism, an output determining step of determining the power to be added to the mass body from a control map prepared in advance, and an output control step of adding the power determined in the output determining step to the mass body. With this configuration, the same working effects as the above can be obtained.

"Advantageous Effects of Invention

"According to the vibration control device according to the present invention, there can be provided a vibration control device which can automatically suppress vibration of a vibrating body without installing a vibration detection sensor on the vibrating body such as a rotary machine, a reciprocating machine or the like, or the vibration control device, or without controlling a rotational speed or phase of the vibration control device. Furthermore, a low-cost vibration control device can be provided.

BRIEF DESCRIPTION OF DRAWINGS

"FIG. 1 is a schematic diagram illustrating a vibration control device of an embodiment according to the present invention.

"FIG. 2 are plan views illustrating an operation of the vibration control device.

"FIG. 3 is a schematic diagram illustrating a vibration control device of another embodiment according to the present invention.

"FIG. 4 are plan views illustrating an operation when there are two mass bodies.

"FIG. 5 are schematic diagrams illustrating a vibration control device of still another embodiment according to the present invention.

"FIG. 6 is a schematic diagram illustrating a mass body of the vibration control device of still another embodiment according to the present invention.

"FIG. 7 is a graph illustrating a vibration control performance of the vibration control device.

"FIG. 8 is a diagram illustrating an outline of a prior-art automatic balancer."

For more information, see this patent application: Yoshitake, Yutaka; Kajiwara, Shuhei. Vibration Control Device and Control Method Therefor. Filed May 16, 2012 and posted August 21, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1093&p=22&f=G&l=50&d=PG01&S1=20140814.PD.&OS=PD/20140814&RS=PD/20140814

Keywords for this news article include: Mitsui Engineering & Shipbuilding Co. Ltd.

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Source: Journal of Engineering


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