Patent Description:
In recent years, various vibration power generation devices that generate power by electromagnetic induction or piezoelectric phenomenon using vibration have been developed. For example, a vibration power generation device has been proposed in which a weight is installed at the end of a magnetostrictive rod wound with a coil, and the vibration of the weight causes the magnetostrictive rod to vibrates, and partially expand and contract, generating electricity through the reverse magnetostriction effect (for example, see International Publication <CIT>).

As a method of vibrating a weight in such a vibration power generation device, it is conceivable to place the weight in a fluid to generate a Karman vortex to cause self-excitation vibration of the weight. In this case, when the vibration frequency of the weight caused by the Karman vortex (vortex shedding frequency) matches the natural frequency of the vibration system consisting of the weight and magnetostrictive rod, a lock-in phenomenon occurs and the weight vibrates significantly, thus improving the power generation efficiency of the vibration power generation device.

However, it is known that, for example, if the weight is cylindrical, the Strouhal number is almost constant, and as the fluid flow velocity changes, the vortex shedding frequency also changes. As a result, it is difficult to maintain a state in which the vortex shedding frequency matches the natural frequency of the vibration system consisting of weights and magnetostrictive rods, and the power generation efficiency of the vibration power generation device may decrease. Therefore, the conventional vibration power generation devices still have room for improvement in terms of power generation efficiency.

An object of the present invention to provide a vibration power generation device and a moving object having high power generation efficiency.

According to the present invention said object is solved by a vibration power generation device having the features of independent claims <NUM> or <NUM>. Moreover, according to the present invention said object is solved by a moving object according to claim <NUM>. Preferred embodiments are laid down in the dependent claims.

According to a preferred embodiment, a vibration power generation device, comprises a vibration exciting body in which vibration is caused by a flowing fluid, a vibrated body which is oscillatable and is connected to the vibration exciting body, and a power generator that generates electricity by oscillation of the vibrated body, wherein the vibration exciting body is disposed in proximity to a wall surface, and vibration is caused in the vibration exciting body by a fluid flowing along the wall surface.

According to this configuration, the vibration exciting body is disposed in proximity to the wall surface, which aids the vibration of the vibration exciting body, thus increasing the vibration of the vibration exciting body even outside of the flow velocity range where lock-in phenomenon is associated. That is, even if the vortex shedding frequency of the vibration exciting body does not match the natural frequency of the vibration system consisting of the vibration exciting body and the vibrated body, the vibration exciting body can be sufficiently vibrated, which can further improve the power generation efficiency.

Further features of the present invention will become apparent from the following description of preferred embodiments with reference to the attached drawings.

The above and other elements, features, steps, characteristics and advantages of the present teaching will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings.

Hereinafter, preferred embodiments of the present teaching will be described with reference to the drawings.

<FIG> illustrate the configuration of the vibration power generation device according to an embodiment of the present teaching. <FIG> is a side view of the vibration power generation device, <FIG> is a plan view of the vibration power generation device, and <FIG> is a side view of a modification of the vibration power generation device.

In <FIG>, a vibration power generation device <NUM> has a vibration exciting body <NUM>, which is a long weight, and two long plate-shaped frames <NUM> connected at one end to the vibration exciting body <NUM>. The frames <NUM> are disposed parallel to each other in plan view. A bar-shaped magnetostrictive plate <NUM> is attached to each of the frames <NUM>, and a coil <NUM> is wound around the frame <NUM> and the magnetostrictive plate <NUM>. The magnetostrictive plate <NUM> and the coil <NUM> constitute a power generator.

The frames <NUM> are made of a magnetic material, for example, carbon steel (SS400 material, SC material, or SK material) or ferritic stainless steel (for example, SUS430). The frames <NUM> are U-shaped in lateral view. In the frames <NUM>, the portions facing each other through a bend portion 12a constitutes a base portion 12b and an arm portion 12c (vibrated body), respectively. The base portion 12b is attached and fixed to a structure or moving object. In the present embodiment, the structure or moving object to which the base portion 12b is attached does not actively vibrate. The vibration exciting body <NUM> is attached to the end of the arm portion 12c. Furthermore, the magnetostrictive plate <NUM> and the coil <NUM> described above are attached to the arm portion 12c between the vibration exciting body <NUM> and the bend portion 12a of the frame <NUM>, but the arm portion 12c is not fixed to the structure or moving object. Thus, in the frame <NUM>, the arm portion 12c functions as a cantilever beam with the bend portion 12a side as the fixed end and the vibration exciting body <NUM> side as the free end. Therefore, when the vibration exciting body <NUM> vibrates in the vertical direction in <FIG>, the arm portion 12c oscillates in the vertical direction in <FIG> around the fixed end due to the vibration of the vibration exciting body <NUM>. The frames <NUM> may be channel-shaped or V-shaped in lateral view.

The magnetostrictive plate <NUM> is made of a ductile magnetostrictive material, and is made of, for example, an iron-gallium alloy, an iron-cobalt alloy, an Fe-Al alloy, or an Fe-Si-B alloy. Furthermore, a magnetostrictive material to which compressive stress has been applied by subjecting it to stress annealing treatment in advance may be used as the material constituting the magnetostrictive plate <NUM>. The magnetostrictive material constituting the magnetostrictive plate <NUM> may be in an amorphous state as well as in a crystalline state. The magnetostrictive plate <NUM> is attached to the outer surface of the arm portion 12c (the upper surface of the arm portion 12c in <FIG>) by, for example, soldering, waxing, resistance welding, laser welding, or ultrasonic bonding.

The material constituting the vibration exciting body <NUM> is not particularly limited, and is preferably a high specific gravity material such as Anviloy, in order to vibrate the vibration exciting body <NUM> from low flow velocities. The vibration exciting body <NUM> is constituted by a cylindrical member in this case; however, which may be a long member to which a plurality of the frames <NUM> can be attached, for example, a rectangular columnar member (<FIG>).

<FIG> are side views to illustrate power generation by the vibration power generation device <NUM> of <FIG>. In <FIG>, the vibration exciting body <NUM> vibrates in the vertical direction in the figure. As illustrated in <FIG>, when the vibration exciting body <NUM> moves upward, the arm portion 12c warps upward and the magnetostrictive plate <NUM> attached to the upper surface of the arm portion 12c is compressed in the longitudinal direction of the arm portion 12c (see arrows in the figure). As illustrated in <FIG>, when the vibration exciting body <NUM> moves downward, the arm portion 12c warps downward and the magnetostrictive plate <NUM> attached to the upper surface of the arm portion 12c is extended in the longitudinal direction of the arm portion 12c (see arrows in the figure). That is, when the vibration exciting body <NUM> vibrates in the vertical direction, the extension and compression of the magnetostrictive plate <NUM> is repeated. At this time, since compressive and tensile stresses act alternately on the magnetostrictive plate <NUM>, changes in the magnetic flux flowing through the plate <NUM> are repeated due to the reverse magnetostriction effect. This causes a continuous change in the magnetic flux through the coil <NUM>, which generates an electromotive force in the coil <NUM> to generate electricity.

Various methods are possible to vibrate the vibration exciting body <NUM> in the vertical direction. An example of a possible method is to place the vibration exciting body <NUM> in a fluid to create a Karman vortex downstream, causing the vibration exciting body <NUM> to vibrate vortically (vortex induced vibration). However, it is not known what fluid vibration phenomena occur in the vibration exciting body <NUM> when the vibration exciting body <NUM> is disposed in proximity to a wall surface of a structure or the like in a fluid. On the other hand, it is known that various fluidic effects can be obtained when an object is brought into close proximity to a wall surface or the like to narrow the flow path between the object and the wall surface.

Therefore, the inventors et al. conducted experiments using a circulating water tank to clarify what fluid vibration phenomena occur in the vibration exciting body <NUM> when the vibration exciting body <NUM> is disposed in proximity to a wall surface in a fluid.

<FIG> illustrates a schematic drawing of the configuration of a circulating water tank used in an experiment to observe the fluid vibration phenomena that occur when the vibration exciting body <NUM> of the vibration power generation device <NUM> is disposed in proximity to a wall surface. In <FIG>, a vibration experimental device <NUM> that imitates the vibration power generation device <NUM> was fixed to a flat wall surface <NUM> of a circulating water tank <NUM> where a uniform water flow was occurring, indicated by the arrow in the figure. The vibration experimental device <NUM> has a columnar body <NUM> that imitates the vibration exciting body <NUM>, and two U-shaped frames <NUM> that imitate the frames <NUM>. In the vibration experimental device <NUM>, each of the U-shaped frames <NUM> is not directly attached to the columnar body <NUM>. Two arms <NUM> were attached to the columnar body <NUM>, and a block-shaped height adjustment jig <NUM> was sandwiched between each of the arms <NUM> and the U-shaped frames <NUM>. The vibration experimental device <NUM> was disposed in the circulating water tank <NUM> so that the longitudinal direction of the columnar body <NUM> was orthogonal to the water flow, the columnar body <NUM> was parallel to the wall surface <NUM>, and the longitudinal direction of each U-shaped frame <NUM> was parallel to the water flow. Since the purpose of this experiment was to observe fluid vibration phenomena, the vibration experimental device <NUM> was not provided with components equivalent to the magnetostrictive plate <NUM> and the coil <NUM>. Furthermore, since the wall surface <NUM> of the circulating water tank <NUM> did not vibrate, the vibration in the columnar body <NUM> was not caused by the vibration of the wall surface <NUM>, but only by the action of the fluid, such as the generation of vortices.

In the experiment, a plurality of the height adjustment jigs <NUM> of different heights were prepared, and the distance S between the columnar body <NUM> and the wall surface <NUM> was changed by replacing the height adjustment jigs <NUM>. In addition, a cylindrical member (sample <NUM>) and three types of rectangular columnar members (samples <NUM> to <NUM>) having cross sectional aspect ratios that differ from one another were prepared as the columnar body <NUM>. For each of the samples <NUM> to <NUM>, vibrations occurred in the vibration experimental device <NUM> were observed when the distance S between the columnar body <NUM> and the wall surface <NUM> was changed. The samples <NUM> and <NUM> were made of stainless steel, while the samples <NUM> and <NUM> were made of Anviloy.

The circulating water tank <NUM> includes a laser displacement meter <NUM>, a laser Doppler velocimeter (LDV) <NUM>, and a pitot tube <NUM>. The laser displacement meter <NUM> measured the vibratory displacement of the columnar body <NUM> relative to the wall surface <NUM>, the LDV <NUM> measured the velocity variation of the water flow behind the columnar body <NUM>, and the pitot tube <NUM> measured the velocity U of the water relative to the wall surface <NUM>. Furthermore, a computer <NUM> compiled the measurement results of the laser displacement meter <NUM>, the LDV <NUM>, and the pitot tube <NUM> to calculate the angle of deviation θ of the vibration in the columnar body <NUM>, vortex shedding frequency fw, and reduced velocity Vr to be described later.

First, as illustrated in <FIG>, a cylindrical member as the sample <NUM> was used as the columnar body <NUM>. The longitudinal length of the columnar body <NUM> is <NUM>. The cross-sectional shape of the columnar body <NUM>, parallel to the direction of water flow and orthogonal to the wall surface <NUM>, was circular, and the diameter H of the circular shape was <NUM>. The total length r (see <FIG>) of the vibration system (hereinafter referred to as the "experimental vibration system"), which includes the columnar body <NUM>, the arm portion of the U-shaped frame <NUM>, the height adjustment jig <NUM>, and the arm <NUM>, was <NUM>.

In Experiment <NUM>, the water velocity U was varied in the range of <NUM>/s to <NUM>/s, and the gap S between the wall surface <NUM> and the columnar body <NUM> was varied in steps to observe the vibration occurred in the columnar body <NUM>. Specifically, the gap spacing ratio S/H was varied in four steps of <NUM>, <NUM>, <NUM> and <NUM>. The observation results of the vibration are illustrated in the graph in <FIG>. Here, when a waveform vibration with an angle of vibration θ of <NUM> deg or more was observed, it was judged that vibration was occurring in the columnar body <NUM>.

The horizontal axis of the graph in <FIG> is the reduced velocity Vr, and the vertical axis is the angle of vibration θ of the experimental vibration system (see <FIG>). The reduced velocity Vr is the dimensionless velocity of water corrected for the effect of the blockage of water flowing between the wall surface <NUM> and the columnar body <NUM>. When the natural frequency of the experimental vibration system is fc, the reduced velocity Vr is expressed by the following equation (<NUM>): <MAT>.

In addition, the resonant reduced velocity was calculated from the vortex shedding frequency fw when no vibration occurred in the columnar body <NUM> at a gap spacing ratio S/H = <NUM>, and a resonant reduced velocity value of approximately <NUM> was obtained. Vortex induced vibration is expected to increase the vibration of the columnar body <NUM> near the resonant reduced velocity, and the resonant reduced velocity is indicated by the dashed line in the graph in <FIG>.

As a result of the observation, as illustrated in the graph in <FIG>, for any gap spacing ratio S/H, vibration occurred in the columnar body <NUM> from the reduced velocity Vr ≈ <NUM>, which is near the resonant reduced velocity, indicating that vibration is caused mainly by vortex induced vibration in the case of the cylindrical member.

At a gap spacing ratio S/H = <NUM>, the experiment was stopped because the angle of vibration θ increased rapidly when the reduced velocity Vr exceeded <NUM> or so and the columnar body <NUM> collided with the wall surface <NUM>. At a gap spacing ratio S/H = <NUM>, the angle of vibration θ increased until the reduced velocity Vr reached <NUM>, after which the angle of vibration θ decreased, but the columnar body <NUM> was still vibrating even when the reduced velocity Vr was above <NUM>. At a gap spacing ratio S/H = <NUM>, the angle of vibration θ increased until the reduced velocity Vr reached <NUM>, after which the angle of vibration θ decreased, but the columnar body <NUM> was still vibrating even when the reduced velocity Vr was above <NUM>. At a gap spacing ratio S/H = <NUM>, the angle of vibration θ increased until the reduced velocity Vr reached <NUM>, after which the angle of vibration θ decreased, but the columnar body <NUM> was still vibrating until the reduced velocity Vr reached <NUM>.

As can be seen from the graph in <FIG>, the smaller the gap spacing ratio S/H, the larger the angle of vibration θ becomes and the wider the range of reduced velocity Vr over which vibration occurs in the columnar body <NUM>. This is considered to be because the closer the columnar body <NUM>, which is a cylindrical member, is to the wall surface <NUM>, the larger the gap variation ratio, which is the ratio of the difference between the maximum gap Smax and the minimum gap Smin to the maximum gap Smax as expressed by the following equation (<NUM>), and thus the pressure variation of the water flow acting on the columnar body <NUM> also becomes larger, which contributes to vibration.

The maximum gap Smax is the gap S when the columnar body <NUM> is farthest from the wall surface <NUM>, and the minimum gap Smin is the gap S when the columnar body <NUM> is closest to the wall surface <NUM>.

Next, as illustrated in <FIG>, a rectangular columnar member as the sample <NUM> was used as the columnar body <NUM>. The longitudinal length of the columnar body <NUM> is <NUM>. The cross-sectional shape of the columnar body <NUM>, parallel to the direction of water flow and orthogonal to the wall surface <NUM>, was rectangular. Referring to <FIG>, the length H of the columnar body <NUM> in the direction orthogonal to the wall surface <NUM> was <NUM>, and the length D in the direction parallel to the direction of water flow was <NUM>. That is, the aspect ratio D/H of the columnar body <NUM> was set to <NUM>. The total length r of the experimental vibration system was <NUM>.

In Experiment <NUM>, as in Experiment <NUM>, the water velocity U was varied in the range of <NUM>/s to <NUM>/s, and the gap spacing ratio S/H was varied in four steps of <NUM>, <NUM>, <NUM>, and <NUM>, and the vibration occurred in the columnar body <NUM> was observed. Also in Experiment <NUM>, when a waveform vibration with an angle of vibration θ of <NUM> deg or more was observed, it was determined that the columnar body <NUM> was vibrating.

<FIG> is a graph illustrating the observation results of vibration of the columnar body <NUM> when the aspect ratio D/H of the columnar body <NUM> is <NUM>. The description of the vertical and horizontal axes in <FIG> is the same as that of the vertical and horizontal axes of the graph in <FIG>. The resonant reduced velocity in Experiment <NUM> is approximately <NUM>, which is indicated by the dashed line in the graph in <FIG>.

As illustrated in the graph in <FIG>, at a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, and then the angle of vibration θ increased rapidly and the columnar body <NUM> collided with the wall surface <NUM>, so the experiment was stopped. At a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, then the angle of vibration θ increased rapidly until the reduced velocity Vr reached <NUM>, and then the angle of vibration θ was almost maintained until the reduced velocity Vr reached <NUM>. At a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, then the angle of vibration θ increased rapidly after when the reduced velocity Vr exceeded <NUM>, then the angle of vibration θ decreased when the reduced velocity Vr exceeded <NUM>, and no vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>. Also at a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, then the angle of vibration θ increased rapidly when the reduced velocity Vr exceeded <NUM>, and then the angle of vibration θ decreased rapidly when the reduced velocity Vr exceeded <NUM>, and no vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>.

As can be seen from the graph in <FIG>, in Experiment <NUM>, except for the case where the gap spacing ratio S/H = <NUM>, large vibration occurred in the columnar body <NUM> from the point when the reduced velocity Vr was much lower than the resonant reduced velocity. This is considered to be because the closer the columnar body <NUM>, which was a rectangular columnar member, was to the wall surface <NUM>, the larger the above-described gap variation ratio between the wall surface <NUM> and the columnar body <NUM> becomes, resulting in larger fluctuations in the pressure of the water flow acting on the columnar body <NUM>, which in turn facilitated the generation of low-speed galloping vibrations. The absence of low-speed galloping vibration when the gap spacing ratio S/H = <NUM>, where the columnar body <NUM> is disposed relatively far from the wall surface <NUM>, was considered to support this consideration.

Next, a rectangular columnar member as the sample <NUM> was used as the columnar body <NUM>. The longitudinal length of the columnar body <NUM> is <NUM>. The cross-sectional shape of the columnar body <NUM>, parallel to the direction of water flow and orthogonal to the wall surface <NUM>, was rectangular. Referring to <FIG>, the length H of the columnar body <NUM> was <NUM> and the length D was <NUM>. That is, the aspect ratio D/H of the columnar body <NUM> was set to <NUM>. The total length r of the experimental vibration system was <NUM>.

As illustrated in the graph in <FIG>, when the gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, and when the reduced velocity Vr exceeded <NUM>, the angle of vibration θ decreased once, after which the angle of vibration θ increased slightly, without decreasing significantly, until the reduced velocity Vr reached <NUM>. At a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, and then the angle of vibration θ increased until the reduced velocity Vr reached <NUM>. At a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, and then the angle of vibration θ increased until the reduced velocity Vr reached <NUM>. Also at a gap spacing ratio S/H = <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, then the angle of vibration θ increased until the reduced velocity Vr reached <NUM>, and then the angle of vibration θ decreased rapidly when the reduced velocity Vr exceeded <NUM>.

As can be seen from the graph in <FIG>, in Experiment <NUM>, vibrations occurred in the columnar body <NUM> from a reduced velocity Vr much lower than the resonant reduced velocity for all gap spacing ratios. As in Experiment <NUM>, this is considered to be due to the proximity of the columnar body <NUM>, which is a rectangular columnar member, to the wall surface <NUM>, which facilitated the generation of low-speed galloping vibration. As illustrated in the graph of <FIG>, the smaller the gap spacing ratio S/H, i.e., the closer the columnar body <NUM> is to the wall surface <NUM>, the lower the region of the reduced velocity Vr from which low-speed galloping vibration is excited, which supports this consideration. At the gap spacing ratio S/H = <NUM> and S/H = <NUM>, the angle of vibration θ did not decrease even after the reduced velocity Vr exceeded the resonant reduced velocity. This is considered to be due to the occurrence of high-speed galloping vibrations when the reduced velocity Vr exceeds the vicinity of the resonant reduced velocity where vortex induced vibration becomes dominant.

Next, a rectangular columnar member as the sample <NUM> was used as the columnar body <NUM>. The longitudinal length of the columnar body <NUM> is <NUM>. The cross-sectional shape of the columnar body <NUM>, parallel to the direction of the water flow and orthogonal to the wall surface <NUM>, was square. That is, both the length H and length D of the columnar body <NUM> illustrated in <FIG> are <NUM>, and the aspect ratio D/H of columnar body <NUM> was set to <NUM>. The total length r of the experimental vibration system was <NUM>.

As illustrated in the graph in <FIG>, when the gap spacing ratio S/H = <NUM>, although vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, the angle of vibration θ did not increase until the reduced velocity Vr exceeded <NUM>, and although the angle of vibration θ increased somewhat near the resonant reduced velocity, the angle of vibration θ decreased thereafter as the reduced velocity Vr increased. On the other hand, in any case of gap spacing ratios S/H = <NUM>, <NUM>, and <NUM>, vibration occurred in the columnar body <NUM> when the reduced velocity Vr exceeded <NUM>, and then the angle of vibration θ increased even when the reduced velocity Vr exceeded <NUM>.

As can be seen from the graph in <FIG>, also in Experiment <NUM>, low-speed galloping vibration was excited by the proximity of the columnar body <NUM>, which is a rectangular columnar member, to the wall surface <NUM> at all gap spacing ratios. At the gap spacing ratio S/H = <NUM> in Experiment <NUM>, the angle of vibration θ decreased after the reduced velocity Vr exceeded the resonant reduced velocity, and the similar tendency was observed at the gap spacing ratio S/H = <NUM> in Experiment <NUM>, while at the gap spacing ratios S/H = <NUM>, <NUM>, and <NUM> in Experiment <NUM>, the angle of vibration θ increased after the reduced velocity Vr exceeded the resonant reduced velocity, and a similar tendency was observed at the gap spacing ratios S/H = <NUM> and <NUM> in Experiment <NUM>. This also indicates that excessive proximity of the columnar body <NUM> to the wall surface <NUM> is not desirable to generate high-speed galloping vibrations.

The observation results from Experiments <NUM> to <NUM> yielded the following findings. By disposing the columnar body <NUM> in a water flow in proximity to the wall surface <NUM>, the gap variation ratio increases, and the pressure variation of the water flow acting on the columnar body <NUM> also increases. Therefore, not only vortex induced vibration occurring near the resonant reduced velocity, but also low-speed galloping vibration can be generated at low reduced velocities. In addition, under some conditions, high velocity galloping vibration can be generated even when the reduced velocity exceeds the resonant reduced velocity. As a result, the vibration of the columnar body <NUM> can be maintained even when the water velocity changes.

Applying this finding to the vibration power generation device <NUM>, in an embodiment of the present teaching, the vibration exciting body <NUM> is disposed in proximity to a wall surface <NUM> of the structure or moving object to which the base portion 12b of the frame <NUM> is attached, in the flow of a fluid such as gas or water. In particular, based on the observation results of Experiments <NUM> to <NUM>, (here, the distance between the wall surface <NUM> and the vibration exciting body <NUM> is put as a gap S, and the length of the vibration exciting body <NUM> in the direction orthogonal to the wall surface <NUM> is put as a length H), by setting the gap spacing ratio S/H to <NUM> or less, the gap variation ratio increases and the pressure variation of the fluid acting on the columnar body <NUM> also increases, which allows low-speed galloping vibrations to be generated at low reduced velocities, and thus the vibration of the vibration exciting body <NUM> can be maintained even when the fluid flow velocity changes. As a result, the power generation efficiency of the vibration power generation device <NUM> can be further improved.

More specifically, in the embodiment of the present teaching, when the cross-sectional shape of the vibration exciting body <NUM> parallel to the fluid flow direction and orthogonal to the wall surface is circular, as indicated in the observation results of Experiment <NUM>, keeping the reduced velocity Vr of the fluid <NUM> or more can generate vibration in the vibration exciting body <NUM> and further improve the power generation efficiency of the vibration power generation device <NUM>.

When the cross-sectional shape of the vibration exciting body <NUM> parallel to the fluid flow direction and orthogonal to the wall surface is rectangular and the aspect ratio D/H of the cross-sectional shape is <NUM>, as indicated in the observation results of Experiment <NUM>, keeping the reduced velocity Vr of the fluid <NUM> or more can generate vibration in the vibration exciting body <NUM> and further improve the power generation efficiency of the vibration power generation device <NUM>.

Furthermore, when the cross-sectional shape of the vibration exciting body <NUM> is rectangular and the aspect ratio D/H of the cross-sectional shape is <NUM>, as indicated in the observation results of Experiment <NUM>, keeping the reduced velocity Vr of the fluid <NUM> or more can generate vibration in the vibration exciting body <NUM> and further improve the power generation efficiency of the vibration power generation device <NUM>.

When the cross-sectional shape of the vibration exciting body <NUM> is rectangular and the aspect ratio D/H of the cross-sectional shape is <NUM>, as indicated in the observation results of Experiment <NUM>, keeping the reduced velocity Vr of the fluid <NUM> or more can generate vibration in the vibration exciting body <NUM> and further improves the power generation efficiency of the vibration power generation device <NUM>.

Since the present embodiment is based on the findings of Experiments <NUM> to <NUM>, which were conducted using the columnar bodies <NUM> with an aspect ratio D/H of <NUM> or less, the aspect ratio D/H of the vibration exciting body <NUM> is also preferably <NUM> or less (D/H ≤ <NUM>). Since the present embodiment is based on the findings of Experiments <NUM> to <NUM>, in which the wall surface <NUM> of the circulating water tank <NUM> do not vibrate, it is assumed that the wall surface of the structure or moving object to which the base portion 12b of the frame <NUM> is attached do not vibrate.

According to the present embodiment, as described above, by disposing the vibration exciting body <NUM> in proximity to the wall surface, low-speed galloping vibration can be generated at a low reduced velocity Vr, which allows the vibration exciting body <NUM> to vibrate even in a large vibration power generation device <NUM>, where the natural frequency is lower. As a result, the use of a large vibration power generation device <NUM> can further improve power generation efficiency due to the synergistic effect of the larger size of the vibration power generation device <NUM> and the expanded range of reduced velocities at which the vibration exciting body <NUM> vibrates.

In the present embodiment, the vibration power generation device <NUM> has two frames <NUM>, but the number of the frames <NUM> is not limited to two, but may be one, three, or more. When the number of the frames <NUM> is three or more, the power generation efficiency can be improved by providing the magnetostrictive plate <NUM> and the coil <NUM> on each of the frames <NUM>.

The preferred embodiments have been described above, but the present teaching is not limited to the above-described embodiments, and various variations and changes are possible within the scope of the invention defined by the claims.

For example, in the vibration power generation device <NUM>, the oscillation of the arm portion 12c was used to expand and compress the magnetostrictive plate <NUM> to generate electricity. As an alternative, a piezoelectric element may be provided instead of the magnetostrictive plate <NUM>, and power may be generated by deforming the piezoelectric element using the oscillation of the arm portion 12c. Alternatively, a magnetic material may be provided instead of the magnetostrictive plate <NUM>, and the arm portion 12c may be configured to move the magnetic material relative to the coil using the oscillation of the arm portion 12c to generate electricity by electromagnetic induction. The arm portion 12c of the vibration power generation device <NUM> itself may be made of a magnetostrictive material and the magnetostrictive plate <NUM> may be eliminated.

The vibration exciting body <NUM> of the vibration power generation device <NUM> is not limited to a columnar body with a circular or rectangular cross section, but may also be a columnar body with a polygonal cross section other than rectangular (a square/quadrangular).

In Experiments <NUM> to <NUM>, the vibration experimental device <NUM> was attached to the wall surface <NUM> so that the bend portion of the U-shaped frame <NUM> was disposed downstream of the water flow, but the location of the bend portion is not limited. For example, in the vibration power generation device <NUM>, the bend portion 12a of the frame <NUM> may be disposed upstream of the fluid from the vibration exciting body <NUM>.

In the present embodiment, as illustrated in <FIG>, the arm portion 12c of the frame <NUM> is disposed parallel to the wall surface <NUM>, but the arm portion 12c does not have to be disposed parallel to the wall surface <NUM> as long as the vibration exciting body <NUM> is disposed in proximity to the wall surface <NUM> and the arm portion 12c is oscillatable. Similarly, the arm portion 12c does not have to be disposed parallel to the direction of the fluid flow.

The applications of the vibration power generation device <NUM> are described below.

<FIG> illustrate a wind following plate <NUM> with the vibration power generation device <NUM> applied thereto. In <FIG>, the wind following plate <NUM> is vertically erected against a disk-shaped base <NUM> and is configured to be rotatable around the central axis of the base <NUM>. The axis of rotation of the wind following plate <NUM> is set offset from the center of the wind following plate <NUM>. Therefore, when the wind following plate <NUM> is disposed in a fluid flow, for example, an air flow, the wind following plate <NUM> changes its orientation so that its surface is substantially parallel to the direction of the air flow (see white arrows in the figure). That is, the wind following plate <NUM> changes its direction following the air flow. On each of the two sides of the wind following plate <NUM>, the vibration power generation device <NUM> is disposed so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the air flow, the vibration exciting body <NUM> is substantially parallel to the surface of the wind following plate <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the air flow.

Since the wind following plate <NUM> follows the air flow, the probability of air flow on the surface of the wind following plate <NUM> can be increased. This can increase the frequency at which the vibration exciting body <NUM> of the vibration power generation device <NUM> vibrates, thereby further improving the power generation efficiency by the vibration power generation device <NUM>.

Each of the number of the frames <NUM> and the number of the coils <NUM> that each vibration power generation device <NUM> has is not limited to two; each vibration power generation device <NUM> may have three or more frames <NUM> and coils <NUM>, as shown in <FIG>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated.

<FIG> illustrates an aircraft <NUM> to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed on the surface of each main wing <NUM> of the aircraft <NUM>. In <FIG>, the magnetostrictive plate <NUM> and the coil <NUM> are not illustrated.

In the aircraft <NUM>, the vibration exciting body <NUM> is disposed near the leading edge of each of the main wings <NUM> so that its longitudinal direction is along the leading edge of the main wings <NUM>. The vibration power generation device <NUM> is disposed on each of the main wing <NUM> so that the vibration exciting body <NUM> is substantially parallel to the surface of the main wing <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the air flow. During the flight of the aircraft <NUM>, there is a constant air flow on the surfaces of the main wings <NUM>, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>. Since the long vibration exciting body <NUM> is disposed near the leading edge of each of the main wings <NUM>, the vibration exciting body <NUM> also can function as a vortex generator to reduce atmospheric drag. The location of the vibration power generation device <NUM> is not limited to the surface of the main wings <NUM>. The vibration power generation device <NUM> may be disposed on any surface of the aircraft <NUM> as long as the location does not interfere with flight or takeoff/landing.

<FIG> illustrates a portion of a train <NUM> to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed on the surface of a sound insulation plate <NUM> that insulates the wind noise of a pantograph <NUM> of the train <NUM>. In <FIG>, the magnetostrictive plate <NUM> and the coil <NUM> are not illustrated.

In the train <NUM>, the vibration power generation device <NUM> is disposed on the sound insulation plate <NUM> so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the air flow generated while the the train <NUM> is running, the vibration exciting body <NUM> is substantially parallel to the surface of the sound insulation plate <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the above air flow. There is a constant air flow on the surface of the sound insulation plate <NUM> while the train <NUM> is running, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>. The location of the vibration power generation device <NUM> is not limited to the surface of the sound insulation plate <NUM>. The vibration power generation device <NUM> may be disposed on anywhere of the train <NUM> vehicle surfaces as long as the location does not interfere with running.

<FIG> illustrates an automobile <NUM> to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed on the surface of the automobile <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the automobile <NUM>, the vibration power generation device <NUM> is disposed on the surface of the vehicle so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the air flow generated while the automobile <NUM> is running, the vibration exciting body <NUM> is substantially parallel to the vehicle surface, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the above air flow. There is a constant air flow on the surface of the vehicle while the automobile <NUM> is running, which allows the vibration exciting body <NUM> to constantly vibrate, thereby further improving the power generation efficiency of the vibration power generation device <NUM>. The automobile <NUM> is not limited to a four-wheeled vehicle as illustrated in <FIG>, but may also be a three-wheeled vehicle or other multi-wheeled vehicle.

<FIG> illustrates a motorcycle <NUM> as a saddle-riding vehicle to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed on the surface of the motorcycle <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the motorcycle <NUM>, the vibration power generation device <NUM> is disposed on the surface of the vehicle so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the air flow generated while the motorcycle <NUM> is running, the vibration exciting body <NUM> is substantially parallel to the vehicle surface, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the above air flow. There is a constant air flow on the surface of the vehicle while the motorcycle <NUM> is running, which allows the vibration exciting body <NUM> to constantly vibrate, thereby further improving the power generation efficiency of the vibration power generation device <NUM>. The saddle-riding vehicle to which the vibration power generation device <NUM> is applied is not limited to the motorcycle <NUM> illustrated in <FIG>, but may also be a three-wheeled vehicle or an all terrain vehicle (ATV).

<FIG> illustrates a marine vessel <NUM> to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed on the surface of a hull <NUM> or a cabin <NUM> of the marine vessel <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the marine vessel <NUM>, the vibration power generation device <NUM> is disposed on the surface of the hull <NUM> or the cabin <NUM> so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the flow of air or water generated while the marine vessel <NUM> is traveling, the vibration exciting body <NUM> is substantially parallel to the surface of the hull <NUM> or cabin <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the flow of air or water. There is a constant flow of air or water on the surface of the hull <NUM> and the cabin <NUM> while the marine vessel <NUM> is traveling, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>. In particular, when the vibration power generation device <NUM> is disposed on the surface of the hull <NUM> below the water surface, the fluid acting on the vibration exciting body <NUM> is water. In this case, since the water has a higher density than the air, the variation in the pressure on the vibration exciting body <NUM> is greater, which allows the vibration exciting body <NUM> to vibrate more efficiently, resulting in further improvement of the power generation efficiency of the vibration power generation device <NUM>. The location of the vibration power generation device <NUM> is not limited to the surface of the hull <NUM> or the cabin <NUM>. The vibration power generation device <NUM> may be disposed on the surface of a trim tab <NUM> for posture control.

<FIG> illustrate an outboard motor <NUM> to which the vibration power generation device <NUM> is applied. <FIG> is a side view of the outboard motor <NUM> and <FIG> is a bottom view of the outboard motor <NUM>. In <FIG>, the vibration power generation device <NUM> is disposed on the lower surface of an anti-ventilation plate <NUM> of the outboard motor <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the outboard motor <NUM>, the vibration power generation device <NUM> is disposed on the lower surface of the anti-ventilation plate <NUM> so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the water flow that generated while the marine vessel equipped with the outboard motor <NUM> is traveling, the vibration exciting body <NUM> is substantially parallel to the lower surface of the anti-ventilation plate <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the water flow. There is a constant water flow on the lower surface of the anti-ventilation plate <NUM> while the marine vessel equipped with the outboard motor <NUM> is traveling, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>.

<FIG> illustrates a portion of a marine vessel to which the vibration power generation device <NUM> is applied. In <FIG>, the vibration power generation device <NUM> is disposed upstream of a propeller <NUM> that is configured to generate a propulsive force. Specifically, the vibration power generation device <NUM> is disposed on the surface of each of a plurality of stators <NUM>, which are fin-like members that control the water flow into the propeller <NUM> to reduce the rotational flow by the propeller <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the marine vessel of <FIG>, the vibration power generation device <NUM> is disposed on the surface of each of the stators <NUM> so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the water flow generated while the marine vessel is traveling, the vibration exciting body <NUM> is substantially parallel to the surface of each of the stators <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the water flow. There is a constant water flow on the surface of each of the stators <NUM> while the marine vessel is traveling, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>.

<FIG> illustrate a duct propeller mechanism <NUM> of a marine vessel to which the vibration power generation device <NUM> is applied. <FIG> is a perspective view illustrating duct propeller mechanism <NUM>, and <FIG> is a cross-sectional view of duct propeller mechanism <NUM>. In <FIG>, the vibration power generation device <NUM> is disposed on the inner surface of a duct <NUM> of the duct propeller mechanism <NUM>. In <FIG>, the magnetostrictive plate <NUM> is not illustrated. The reference signs for the vibration exciting body <NUM>, the frame <NUM>, and the coil <NUM> are also omitted.

In the duct propeller mechanism <NUM>, the vibration power generation device <NUM> is disposed on the inner surface of the duct <NUM> so that the longitudinal direction of the vibration exciting body <NUM> is substantially orthogonal to the water flow through inside of the duct <NUM>, the vibration exciting body <NUM> is substantially parallel to the inner surface of the duct <NUM>, and the longitudinal direction of each of the frames <NUM> is substantially parallel to the water flow. There is a constant water flow on the inner surface of the duct <NUM> while the marine vessel is traveling, which allows the vibration exciting body <NUM> to vibrate constantly, thereby further improving the power generation efficiency of the vibration power generation device <NUM>.

Claim 1:
A vibration power generation device (<NUM>) comprising:
a vibration exciting body (<NUM>) configured for vibration caused by a flowing fluid;
a vibrated body (<NUM>) which is oscillatable and is connected to the vibration exciting body (<NUM>); and
a power generator (<NUM>, <NUM>) configured to generate electricity by oscillation of the vibrated body (<NUM>),
wherein the vibration exciting body (<NUM>) is disposed in proximity to a wall surface (<NUM>, <NUM>), and vibration is caused in the vibration exciting body (<NUM>) by a fluid flowing along the wall surface (<NUM>, <NUM>), wherein when a length of the vibration exciting body (<NUM>) in a direction orthogonal to the wall surface (<NUM>, <NUM>) is H and a distance between the wall surface (<NUM>, <NUM>) and the vibration exciting body (<NUM>) is S, a gap spacing ratio satisfies S/H ≤ <NUM>, characterized in that
a cross-section of the vibration exciting body (<NUM>) being parallel to a direction of the fluid flow and orthogonal to the wall surface (<NUM>, <NUM>) is circular, wherein when a flow velocity of the fluid to the wall surface (<NUM>, <NUM>) is U, a natural frequency of a vibration system comprising the vibration exciting body (<NUM>) and the vibrated body (<NUM>) is fc, a reduced velocity of the fluid Vr expressed as Vr = U/(fc × H) is <NUM> or more.