Mechanical energy storage

Abstract

To provide a mechanical energy storage device capable of safely storing energy at high density. [Solution] A mechanical energy storage body 1 comprises a SWCNT rope 10, which is mainly composed of single-walled carbon nanotubes (SWCNT) and thermoplastic resin and has a first end 12 and a second end 14, and a holding mechanism 20 that holds mechanical energy based on the twisted state of the SWCNT rope 10. In the testing phase, the gravimetric energy density of the SWCNT rope reached a maximum of 2.1 MJ / kg, which was more than three times greater than the gravimetric energy density of a lithium-ion secondary battery.

Description

Technical Field

[0001] The present invention relates to a mechanical energy storage body.

Background Art

[0002] In recent years, along with the development of various technologies, particularly electrical, electronic, and communication technologies, research on technologies related to the energy required for the operation of devices using these technologies has been progressing in various aspects. There are very diverse fields related to energy technologies, and among them, energy storage technology is one of the important ones.

[0003] For example, many so-called natural energies are not suitable for steady direct use or power generation, and thus progress in energy storage technology is also essential for expanding their utilization. In addition, with the spread and performance improvement of small electronic communication devices, the need for small-scale energy storage technology at the daily life level is also increasing.

[0004] As an energy source at the daily life level, chemical batteries are generally used, and in particular, the spread of secondary batteries that can be charged as well as discharged is progressing. In recent years, lithium-ion secondary batteries with excellent various performances such as high energy density and high voltage have been widely used. ​​​​​​One example of energy storage technology described above is that which utilizes mechanical energy. Products that store energy as mechanical energy and are used at the everyday level often utilize the elasticity (torsion and strain) of metals or rubber. Well-known examples of such products include mechanical watches equipped with mainsprings and model airplanes with rubber bands used as propeller power. While energy storage technologies using mechanical energy do not pose risks (such as explosions) due to chemical reactions, springs and rubber bands could not store energy at a sufficient density compared to chemical batteries, etc.

[0007] Incidentally, a substance called carbon nanotube (CNT) is known. Carbon nanotubes are nanomaterials with a cylindrical (tubular) carbon skeleton and a diameter on the order of nanometers. Carbon nanotubes have extremely excellent properties, such as superior electrical conductivity compared to metallic copper and much better mechanical strength than steel despite having half the density (mass per unit volume) of aluminum.

[0008] Carbon nanotubes are classified according to the number of layers in their basic cylindrical structure. Single-walled nanotubes are called single-walled carbon nanotubes (SWCNTs), while multi-walled nanotubes are called multi-walled carbon nanotubes (MWCNTs). Multi-walled carbon nanotubes can be manufactured in larger quantities than single-walled nanotubes, and research into their specific applications and commercialization is more advanced than that for single-walled nanotubes.

[0009] Regarding research on mechanical energy using multi-walled carbon nanotubes, the study by Professor Bauman et al. at the University of Texas (USA) on the expansion and contraction of torsion coils using multi-walled carbon nanotubes is well known (see Non-Patent Document 1 and Patent Document 1). These studies primarily focus on driving torsion coils using electricity, light, chemical reactions, etc., and describe how the torsion coils can convert mechanical energy into electrical energy and store it during the process. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Special Publication No. 2015-533521 [Non-patent literature]

[0011] [Non-Patent Document 1] Nature Energy, (English), 2023, volume 8, pp. 203-213 [Non-Patent Document 2] Physical Review Letters,(US),2012,Vol.108,235501 [Non-Patent Document 3] Physical Review Letters,(US),2012,Vol.109,255501 [Overview of the project] [Problems that the invention aims to solve]

[0012] However, the gravimetric energy density of the multi-walled carbon nanotubes reported in Non-Patent Document 1 and Patent Document 1 is at most only 0.0004 MJ / kg per expansion and contraction.

[0013] In 2012, Professor Thomasnek of Michigan State University and Professor Iijima of Meijo University reported that twisted single-walled carbon nanotube bundles acquire excess mechanical energy (see Non-Patent Literature 2). Furthermore, Professor Thomasnek's team suggested that a considerable amount of energy could be stored by twisting single-walled carbon nanotube bundles, and they theoretically predicted the amount of energy that can be stored in a single-walled carbon nanotube bundle (see Non-Patent Literature 3). According to this prediction, the gravimetric energy density of a single-walled carbon nanotube bundle can reach up to 8 MJ / kg.

[0014] As a result of diligent research, the inventors of this invention have discovered that SWCNT ropes, primarily composed of single-walled carbon nanotubes and thermoplastic resin, can store energy at extremely high densities. As will be detailed later, the gravimetric energy density of the SWCNT rope during testing reached a maximum of 2.1 MJ / kg. This far exceeds the gravimetric energy densities reported in Non-Patent Document 1 and Patent Document 1, and is more than three times greater than the gravimetric energy density of lithium-ion secondary batteries. On the other hand, in order to put energy storage technology using carbon nanotubes into practical use, it is necessary to consider specific configurations capable of storing mechanical energy.

[0015] This invention has been made in view of the above problems, and aims to provide a mechanical energy storage body capable of safely storing energy at high density. [Means for solving the problem]

[0016] [1] A mechanical energy storage device according to one embodiment of the present invention is characterized by comprising a SWCNT rope having a first end and a second end, and having single-walled carbon nanotubes and a thermoplastic resin as its main components, and a holding mechanism that holds mechanical energy based on the twisted state of the SWCNT rope.

[0017] [2] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in [1] above), it is preferable that the thermoplastic resin is thermoplastic polyurethane.

[0018] [3] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in [1] or [2] above), it is preferable to further include a housing for housing the SWCNT rope.

[0019] [4] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in [3] above), it is preferable that the first end of the SWCNT rope is fixed to the housing and the second end is connected to the holding mechanism.

[0020] [5] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in [4] above), it is preferable that the SWCNT rope has a structure in which a plurality of single ropes mainly composed of the single-walled carbon nanotubes and the thermoplastic resin are bundled.

[0021] [6] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in [4] or [5] above), the mechanical energy storage body includes a plurality of SWCNT ropes as the SWCNT ropes, and a main rotating shaft connected to the holding mechanism, a sub-rotating shaft connected to the second end of the SWCNT rope, and a rotational force transmission mechanism for transmitting a rotational force between the main rotating shaft and the sub-rotating shaft. It is preferable that the second end of the SWCNT rope is connected to the holding mechanism via the sub-rotating shaft, the rotational force transmission mechanism, and the main rotating shaft.

[0022] [7] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in any one of [4] to [6] above), it is preferable that the SWCNT rope is stored in the housing in a slack state at least when the mechanical energy to be held is at a minimum.

[0023] [8] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in any one of [4] to [7] above), it is preferable to further include a rope folding member that meanders the SWCNT rope within the housing.

[0024] [9] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in any one of [4] to [7] above), it is preferable to further include a partition member for arranging the SWCNT rope in a spiral shape within the housing.

[0025]

[10] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in any one of [4] to [9] above), it is preferable that the holding mechanism has a ratchet mechanism that restricts the rotational direction to a predetermined direction when the mechanical energy is accumulated in the SWCNT rope and releases the restriction on the rotational direction when the mechanical energy is released from the SWCNT rope.

[0026]

[11] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in any one of [1] to

[10] above), it is preferable to further include a power generation mechanism that converts the mechanical energy stored in the SWCNT rope into electrical energy.

[0027]

[12] In the mechanical energy storage body according to an embodiment of the present invention (the mechanical energy storage body described in

[11] above), it is preferable that the power generation mechanism can generate a rotational force by the power supplied from the outside of the mechanical energy storage body and accumulate the mechanical energy in the SWCNT rope.

[0028]

[13] In a mechanical energy storage body according to one embodiment of the present invention (the mechanical energy storage body described in

[11] or

[12] above), it is preferable that the power generation mechanism has a coreless generator.

[0029]

[14] In a mechanical energy storage body according to one embodiment of the present invention (the mechanical energy storage body described in

[11] or

[12] above), the power generation mechanism preferably has an electrostatic generator.

[0030]

[15] In a mechanical energy storage body according to one embodiment of the present invention (a mechanical energy storage body according to any of

[11] to

[14] above), it is preferable that the power generation mechanism is separable from and connectable to the SWCNT rope and the holding mechanism.

[0031]

[16] In a mechanical energy storage body according to one embodiment of the present invention (a mechanical energy storage body according to any one of [1] to

[15] above), it is preferable that the mechanical energy storage body comprises a plurality of SWCNT ropes as the SWCNT rope, and further comprises an interlocking mechanism for linking the twisted state of the SWCNT ropes. [Effects of the Invention]

[0032] The mechanical energy storage body of the present invention comprises a SWCNT rope, which is mainly composed of single-walled carbon nanotubes (SWCNTs) and a thermoplastic resin, and a holding mechanism that holds mechanical energy based on the twisted state of the SWCNT rope. Therefore, it is a mechanical energy storage body that can safely store mechanical energy at high density. [Brief explanation of the drawing]

[0033] [Figure 1] This is a diagram illustrating the mechanical energy storage body 1 according to Embodiment 1. [Figure 2] This is a front view of the mechanical energy storage body 2 according to Embodiment 2. [Figure 3] This is a front view of the mechanical energy storage body 3 according to Embodiment 3. [Figure 4] This is a front view of the mechanical energy storage body 4 according to Embodiment 4. [Figure 5] This is a diagram illustrating the mechanical energy storage body 5 according to Embodiment 5. [Figure 6] This is a diagram illustrating the mechanical energy storage body 6 according to Embodiment 6. [Figure 7] This is a diagram illustrating the mechanical energy storage body 7 according to Embodiment 7. [Figure 8] This is a photograph showing the manufacturing process of a SWCNT rope made of single-walled carbon nanotubes in an example. [Figure 9] This photograph shows the measurement of the gravimetric energy density of the SWCNT rope in the example. [Figure 10] This bar graph shows the gravitational energy density (GED) of a SWCNT rope made of single-walled carbon nanotubes in the example. [Figure 11] This graph shows the performance of the modified SWCNT rope in the example. [Figure 12] This graph shows the gravimetric energy density and power density of major energy storage technologies. [Figure 13] This graph shows the temperature dependence of the performance of y-rope(TPU) in the example. [Figure 14] This graph shows the repeatability characteristics of y-rope(TPU) in the example. [Modes for carrying out the invention]

[0034] The mechanical energy storage body of the present invention will be described below based on the embodiments shown in the figures. Note that the embodiments described below do not limit the invention as defined in the claims. Furthermore, not all of the elements and their combinations described in each embodiment are necessarily essential as means of solving the problems of the present invention. Also, for components having exactly the same function or substantially the same function, even if their shape differs slightly, common reference numerals will be used in each embodiment, and previously given explanations may be omitted.

[0035] [Embodiment 1] Figure 1 is a diagram illustrating the mechanical energy storage body 1 according to Embodiment 1. Figure 1(a) is a front view of the mechanical energy storage body 1, Figure 1(b) is a schematic diagram showing an example of a bundle structure of single-walled carbon nanotubes, Figures 1(c) and 1(d) are perspective views illustrating the ratchet mechanism 22, and Figure 1(e) shows the power generation mechanism 40 separated from other components. In Figures 1(a) and 1(e), the housing 30 is shown as a cross-sectional view so that the inside is visible. The same applies to the front views in Figures 2 to 6, which will be described later. The arrows shown at the top of the ratchet mechanism 22 in Figures 1(c) and 1(d) indicate the direction in which the disc-shaped member 22a can rotate.

[0036] The mechanical energy storage body 1 according to Embodiment 1 comprises a SWCNT rope 10, a holding mechanism 20, a housing 30, and a power generation mechanism 40 (see Figure 1(a)). Each component will be described below.

[0037] The SWCNT rope 10 is a component mainly composed of single-walled carbon nanotubes and thermoplastic resin. The SWCNT rope 10 can also be described as "a thread-like component having a structure in which thermoplastic resin is permeated into a bundle structure of single-walled carbon nanotubes formed by intermolecular forces (particularly van der Waals forces) (see, for example, Figure 1(b))." The SWCNT rope 10 has a first end 12 and a second end 14.

[0038] Here, an example of a manufacturing method for SWCNT rope 10 is described. First, some single-walled carbon nanotubes are grasped and pulled out from a lump-like aggregate of single-walled carbon nanotubes. In this way, other single-walled carbon nanotubes are successively pulled out by intermolecular forces, as they are attracted to the pulled-out single-walled carbon nanotubes, and a filamentous material consisting of single-walled carbon nanotubes having a bundle structure can be obtained. Note that the "lump-like aggregate of single-walled carbon nanotubes" is a common form of single-walled carbon nanotubes as they are after manufacturing or as sold single-walled carbon nanotubes.

[0039] Next, a thermoplastic resin dissolved in a solvent is added to the obtained filamentous material. Then, before the solvent evaporates, the filamentous material is lightly twisted, the solvent is removed by vacuum drying or the like, and microwave irradiation is performed. Microwave irradiation is preferably carried out under a reduced pressure environment. SWCNT rope 10 can be manufactured by the above method (see also the examples described later). Note that the SWCNT rope 10 in Embodiment 1 can also be said to be a single rope made of one rope.

[0040] The thickness of the SWCNT rope 10 is preferably in the range of 10 μm to 2 mm. Regarding the thickness of the SWCNT rope 10, there is a tendency for it to be preferable to make it thinner to improve gravimetric energy density, and to make it thicker to improve strength. Furthermore, the length of the SWCNT rope 10 is preferably in the range of 5 mm to 20 cm. Note that the above examples of thickness and length are based on current knowledge, and the thickness and length of the SWCNT rope in this invention are not limited to these ranges.

[0041] While various resins can be used as the thermoplastic resin in the SWCNT rope 10, current knowledge suggests that thermoplastic polyurethane (TPU) is preferable (see the examples described later).

[0042] The SWCNT rope 10 has its first end 12 fixed to the housing 30 and its second end 14 connected to the holding mechanism 20. Although not shown in the figures, an adhesive (for example, a cyanoacrylate adhesive or an epoxy adhesive) can be used to connect and fix the SWCNT rope 10.

[0043] Although specific illustrations are omitted, it is also preferable that the SWCNT rope 10 is housed in the housing 30 in a state in which it has slack, at least in a state in which the mechanical energy it holds is minimized. In this specification, "state in which it has slack" means a state in which no tension other than that caused by the weight of the SWCNT rope is applied between the first end and the second end of the SWCNT rope.

[0044] The holding mechanism 20 is a mechanism that holds the mechanical energy based on the twisted state of the SWCNT rope 10. The holding mechanism 20 has a ratchet mechanism 22 that restricts the direction of rotation in a predetermined direction when mechanical energy is being stored in the SWCNT rope 10, and releases the restriction on the direction of rotation when mechanical energy is being released from the SWCNT rope 10 (see Figures 1(c) and 1(d)). Note that the ratchet mechanism 22 is not shown in Figure 1(a).

[0045] The ratchet mechanism 22 has a pair of disc-shaped members 22a and 22b having wavy protrusions and indentations with an unequal triangular cross-section, and the rotational direction can be restricted by the engagement of these protrusions and indentations. In the pair of disc-shaped members 22a and 22b, a pressing force is normally applied in a direction that causes the sides with the protrusions and indentations to press against each other, by a spring or the like (not shown) (see Figure 1(c)). On the other hand, when the pressing force is released, the disc-shaped members 22a and 22b separate, releasing the engagement of the protrusions and indentations, and thus releasing the restriction on the rotational direction (see Figure 1(d)). The pressing force can be released by a mechanical release mechanism (not shown). Since such a ratchet mechanism 22 is well known, a detailed explanation is omitted.

[0046] The holding mechanism 20 is positioned to be in contact with one of the outer end faces of the housing 30. The holding mechanism 20 has a holding mechanism rotation shaft 24 connected to the second end 14 of the SWCNT rope 10. The holding mechanism rotation shaft 24 is connected (not shown) to one of the disc-shaped members 22a, 22b of the ratchet mechanism 22 (for example, disc-shaped member 22a), and is also connected to the power generation mechanism 40 via a power generation mechanism connecting member 26.

[0047] The housing 30 is a component that houses the SWCNT rope 10. The housing 30 is a substantially cylindrical component, and a rope fixing member 32 for fixing the first end 12 of the SWCNT rope 10 is arranged on the inner side of the end face opposite the holding mechanism 20. In addition, a through hole (not shown in the diagram) for passing the holding mechanism rotation shaft 24 is formed on the end face of the housing 30 on the side of the holding mechanism 20.

[0048] The power generation mechanism 40 is a mechanism that converts the mechanical energy stored in the SWCNT rope 10 into electrical energy. The power generation mechanism 40 has wiring and terminals for exchanging current with the outside of the mechanical energy storage body 1, but these are widely known and therefore not shown or described. The power generation mechanism 40 preferably has a coreless generator (not shown). It is also preferable that the power generation mechanism 40 has an electrostatic generator (not shown).

[0049] In this specification, "coreless generator" refers to a generator having a structure without a core (iron core). Furthermore, in this specification, "electrostatic generator" refers to a generator that generates electricity by utilizing the attraction and repulsion of static charge. In addition, it is preferable that the electrostatic generator in this invention uses semiconductor material for its moving parts.

[0050] The power generation mechanism 40 has a power generation mechanism rotating shaft 42 that is connected to the holding mechanism 20 and, consequently, the SWCNT rope 10 via a power generation mechanism connecting member 26. The power generation mechanism 40 is connected to the holding mechanism 20 by a mechanical locking mechanism provided on the power generation mechanism connecting member 26, for example, and can be separated from and connected to the SWCNT rope 10 and the holding mechanism 20 (see Figure 1(e)). Any known mechanism that can be unlocked can be used as the mechanical locking mechanism.

[0051] Therefore, the SWCNT rope 10, holding mechanism 20, and housing 30 in the mechanical energy storage unit 1 can also be described as constituting a separable component unit (a so-called cartridge) from the power generation mechanism 40. Consequently, the mechanical energy storage unit 1 can accommodate the replacement of the component unit comprising the SWCNT rope 10, holding mechanism 20, and housing 30, or the replacement of the power generation mechanism 40.

[0052] It is preferable that the power generation mechanism 40 generates rotational force using electricity supplied from outside the mechanical energy storage body 1, thereby accumulating mechanical energy in the SWCNT rope 10. In other words, it is preferable that the power generation mechanism 40 generates rotational force as a motor using electricity supplied from outside, and that this rotational force accumulates mechanical energy (torsion) in the SWCNT rope 10. However, the mechanical energy in the SWCNT rope 10 may also be accumulated by rotational force without going through the power generation mechanism 40.

[0053] Although not shown in the diagram, the mechanical energy storage unit 1 may be equipped with a speed control mechanism between the power generation mechanism 40 and the holding mechanism 20 or SWCNT rope 10 to adjust the rate at which mechanical energy is released (the rotational speed of the holding mechanism's rotating shaft 24).

[0054] The mechanical energy storage body 1 according to Embodiment 1 comprises a SWCNT rope 10 whose main components are single-walled carbon nanotubes and thermoplastic resin, and a holding mechanism 20 that holds mechanical energy based on the twisted state of the SWCNT rope 10, thus becoming a mechanical energy storage body capable of safely storing mechanical energy at high density.

[0055] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, when the thermoplastic resin is thermoplastic polyurethane, it is possible to particularly increase the energy density that the SWCNT rope 10 can store.

[0056] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, since it is equipped with a housing 30 for housing the SWCNT rope 10, the SWCNT rope 10 is not exposed to the outside, making it easier to handle.

[0057] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, since the SWCNT rope 10 has its first end 12 fixed to the housing 30 and its second end 14 connected to the holding mechanism 20, it is possible to store mechanical energy in the SWCNT rope 10 within the housing 30.

[0058] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, when the SWCNT rope 10 is housed in the housing 30 with slack between the first end 12 and the second end 14 in a state where the mechanical energy it holds is at least minimal, it is possible to mitigate the effects of tension generated by the contraction of the SWCNT rope 10 due to twisting.

[0059] Furthermore, in the mechanical energy storage body 1 according to Embodiment 1, the holding mechanism 20 has a ratchet mechanism 22 that restricts the rotation direction to a predetermined direction when mechanical energy is stored in the SWCNT rope 10, and releases the restriction on the rotation direction when mechanical energy is released from the SWCNT rope 10. Therefore, according to the mechanical energy storage body 1 according to Embodiment 1, it is possible to achieve mechanical energy storage using a relatively simple mechanical mechanism.

[0060] Furthermore, the mechanical energy storage body 1 according to Embodiment 1 includes a power generation mechanism 40 that converts the mechanical energy stored in the SWCNT rope 10 into electrical energy, thus enabling energy storage using the SWCNT rope 10.

[0061] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, if the power generation mechanism 40 can generate rotational force using electricity supplied from outside the mechanical energy storage body 1 and store mechanical energy in the SWCNT rope 10, then the mechanical energy storage body 1 can be used like a secondary battery.

[0062] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, when the power generation mechanism 40 has a coreless generator, it is possible to eliminate iron loss due to the iron core and increase the conversion efficiency from mechanical energy to electrical energy.

[0063] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, if the power generation mechanism 40 has an electrostatic generator, the generator can be made significantly smaller and lighter, thus enabling miniaturization and increased efficiency of the mechanical energy storage body 1.

[0064] Furthermore, according to the mechanical energy storage body 1 of Embodiment 1, the power generation mechanism 40 can be separated from and connected to the SWCNT rope 10 and the holding mechanism 20. Therefore, by replacing an SWCNT rope 10 that has run out of mechanical energy with another SWCNT rope 10 that still has mechanical energy stored in it, it is possible to obtain continuous power.

[0065] [Embodiment 2] Figure 2 is a front view of the mechanical energy storage body 2 according to Embodiment 2.

[0066] The mechanical energy storage body 2 according to Embodiment 2 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, but the configuration of the SWCNT rope is different. That is, the SWCNT rope 11 in the mechanical energy storage body 2 has a structure in which multiple single ropes 10a, which are mainly composed of single-walled carbon nanotubes and thermoplastic resin, are bundled together (see Figure 2).

[0067] Each individual rope 10a has basically the same configuration as the SWCNT rope 10 in Embodiment 1. Multiple single ropes 10a are connected together to the holding mechanism rotation shaft 24. The SWCNT rope 11 may have a configuration in which multiple single ropes 10a are arranged in parallel (without entanglement), or it may have a configuration in which multiple single ropes 10a are twisted together.

[0068] Although the configuration of the SWCNT rope in the mechanical energy storage body 2 according to Embodiment 2 differs from that of the mechanical energy storage body 1 according to Embodiment 1, the presence of the SWCNT rope 11 and the holding mechanism 20 makes it a mechanical energy storage body that can safely store mechanical energy at high density, similar to the mechanical energy storage body 1.

[0069] Furthermore, in the mechanical energy storage body 2 according to Embodiment 2, the SWCNT rope 11 has a structure in which multiple single ropes 10a, mainly composed of single-walled carbon nanotubes and thermoplastic resin, are bundled together. Therefore, according to the mechanical energy storage body 2 according to Embodiment 2, the overall strength of the SWCNT rope 11 can be increased, and handling can be made even easier.

[0070] Since the mechanical energy storage body 2 according to Embodiment 2 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, it has the corresponding effect among the effects of the mechanical energy storage body 1.

[0071] [Embodiment 3] Figure 3 is a front view of the mechanical energy storage body 3 according to Embodiment 3.

[0072] The mechanical energy storage body 3 according to Embodiment 3 has basically the same configuration as the mechanical energy storage body according to Embodiment 1, but differs in that it is equipped with multiple SWCNT ropes and a rotational force transmission mechanism, etc.

[0073] The mechanical energy storage body 3 comprises a plurality of SWCNT ropes 10 as SWCNT ropes (see Figure 3). The mechanical energy storage body 3 further comprises a main rotating shaft 50 connected to the holding mechanism 20, a sub-rotating shaft 52 connected to the second end 14 of the SWCNT rope 10, and a rotational force transmission mechanism 54 that transmits rotational force between the main rotating shaft 50 and the sub-rotating shaft 52. The second end 14 of the SWCNT rope 10 in the mechanical energy storage body 3 is connected to the holding mechanism 20 via the sub-rotating shaft 52, the rotational force transmission mechanism 54, and the main rotating shaft 50.

[0074] The main rotating shaft 50 is located approximately in the center of the housing 30 and is connected to the holding mechanism rotating shaft 24. The main rotating shaft 50 and the holding mechanism rotating shaft 24 may be made from the same component.

[0075] Multiple sub-rotating shafts 52 are arranged on the inside of the end face of the housing 30 on the side of the holding mechanism 20. In addition, multiple rope fixing members 32 corresponding to the sub-rotating shafts 52 are arranged on the inside of the end face of the housing 30 opposite to the holding mechanism 20. Since the mechanical energy storage body 3 has two SWCNT ropes 10, the number of sub-rotating shafts 52 is also two. Note that the number of SWCNT ropes 10 may be three or more, in which case the same number of sub-rotating shafts 52 as the number of SWCNT ropes 10 will be required.

[0076] As the rotational force transmission mechanism 54, for example, a timing belt or gears can be used. The timing belt may be a toothed belt, in which case gears are arranged on the main rotating shaft 50 and the sub-rotating shaft 52. Mechanical elements such as gears may be made of metal material, but depending on the size and output of the mechanical energy storage body 3, they may also be made of microfabricated semiconductor material. The rotational force transmission mechanism 54 may consist of a single component or a combination of multiple components. Multiple rotational force transmission mechanisms 54 are attached to the main rotating shaft 50 so as not to interfere with each other.

[0077] The mechanical energy storage body 3 according to Embodiment 3 differs from the mechanical energy storage body 1 according to Embodiment 1 in that it comprises a plurality of SWCNT ropes and a rotational force transmission mechanism, etc. However, because it comprises SWCNT ropes 10 and a holding mechanism 20, it is a mechanical energy storage body that can safely store mechanical energy at high density, similar to the mechanical energy storage body 1.

[0078] Furthermore, the mechanical energy storage body 3 according to Embodiment 3 comprises a plurality of SWCNT ropes 10 as SWCNT ropes, a main rotating shaft 50 connected to the holding mechanism 20, a sub-rotating shaft 52 connected to the second end 14 of the SWCNT rope 10, and a rotational force transmission mechanism 54 that transmits rotational force between the main rotating shaft 50 and the sub-rotating shaft 52. The second end 14 of the SWCNT rope 10 is connected to the holding mechanism 20 via the sub-rotating shaft 52, the rotational force transmission mechanism 54, and the main rotating shaft 50. Therefore, according to the mechanical energy storage body 3 of Embodiment 3, by using a plurality of SWCNT ropes 10, it is possible to increase the amount of mechanical energy that can be stored in a limited space.

[0079] Since the mechanical energy storage body 3 according to Embodiment 3 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, it has the corresponding effect among the effects of the mechanical energy storage body 1.

[0080] [Embodiment 4] Figure 4 is a front view of the mechanical energy storage body 4 according to Embodiment 4.

[0081] The mechanical energy storage body 4 according to Embodiment 4 has basically the same configuration as the mechanical energy storage body according to Embodiment 1, but differs in that it is equipped with a rope folding member. That is, the mechanical energy storage body 4 is equipped with a rope folding member 60 that causes the SWCNT rope 10 to meander within the housing 30 (see Figure 4). The rope folding member 60 is, for example, a pulley.

[0082] The mechanical energy storage body 4 according to Embodiment 4 differs from the mechanical energy storage body 1 according to Embodiment 1 in that it includes a rope folding member, but because it includes an SWCNT rope 10 and a holding mechanism 20, it is a mechanical energy storage body that can safely store mechanical energy at high density, similar to the mechanical energy storage body 1.

[0083] Furthermore, according to the mechanical energy storage body 4 of Embodiment 4, since it is equipped with a rope folding member 60 that causes the SWCNT rope 10 to meander within the housing 30, it becomes possible to use an even longer SWCNT rope 10, and thus it becomes possible to increase the amount of mechanical energy that can be stored in a limited space.

[0084] Since the mechanical energy storage body 4 according to Embodiment 4 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, it has the corresponding effect among the effects of the mechanical energy storage body 1.

[0085] [Embodiment 5]

[0086] Figure 5 is a diagram illustrating the mechanical energy storage body 5 according to Embodiment 5. Figure 5(a) is a front view of the mechanical energy storage body 5, and Figure 5(b) is a cross-sectional view showing the internal structure on the bottom side of the housing 30a.

[0087] The mechanical energy storage body 5 according to Embodiment 5 has basically the same configuration as the mechanical energy storage body according to Embodiment 1, but differs in that it includes a partition member and the shape of the housing. Specifically, the mechanical energy storage body 5 includes a partition member 70 for arranging the SWCNT rope 10 in a spiral shape within the housing 30a (see Figure 5).

[0088] The housing 30a in the mechanical energy storage body 5 is lower in height than the housing 30 in other embodiments and has a shape in which the diameter is greater than the height. In addition to a rope fixing member 32 for fixing the first end 12 of the SWCNT rope 10, the housing 30a has a direction changing member 34 near the center that directs the orientation of the SWCNT rope 10 toward the holding mechanism rotation axis 24. The direction changing member 34 is, for example, a pulley.

[0089] The mechanical energy storage body 5 according to Embodiment 5 differs from the mechanical energy storage body 1 according to Embodiment 1 in that it includes a partition member and has a housing shape, but because it includes an SWCNT rope 10 and a holding mechanism 20, it is a mechanical energy storage body that can safely store mechanical energy at high density, similar to the mechanical energy storage body 1.

[0090] Furthermore, according to the mechanical energy storage body 5 of Embodiment 5, since it is equipped with a partition member 70 for arranging the SWCNT rope 10 in a spiral shape within the housing 30a, it is possible to reduce the height of the housing 30a while increasing the amount of mechanical energy that can be stored in a limited space.

[0091] Since the mechanical energy storage body 5 according to Embodiment 5 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, it has the corresponding effect among the effects of the mechanical energy storage body 1.

[0092] [Embodiment 6] Figure 6 is a diagram illustrating the mechanical energy storage body 6 according to Embodiment 6. Figure 6(a) is a front view of the mechanical energy storage body 6, and Figure 6(b) is a top view of the mechanical energy storage body 6. In Figure 6(a), of the multiple SWCNT ropes 10, holding mechanisms 20, and housings 30, only the one on the left side of the drawing is labeled with a reference numeral. In Figure 6(b), of the multiple holding mechanisms 20 and interlocking mechanisms 80, only the one in the upper left of the drawing is labeled with a reference numeral, and of the multiple cartridges C, only the one at the top of the drawing is labeled with a reference numeral.

[0093] The mechanical energy storage body 6 according to Embodiment 6 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, but differs in that it is equipped with multiple SWCNT ropes and an interlocking mechanism.

[0094] The mechanical energy storage unit 6 comprises multiple SWCNT ropes 10 as SWCNT ropes. The mechanical energy storage unit 6 also comprises an interlocking mechanism 80 that synchronizes the twisting state of the SWCNT ropes 10. Specifically, the mechanical energy storage unit 6 comprises multiple cartridges C, each consisting of an SWCNT rope 10, a holding mechanism 20, and a housing 30, and the holding mechanism rotation shaft 24 of each cartridge C is connected by the interlocking mechanism 80 (see Figure 6).

[0095] The configuration of cartridge C is the same as that of the SWCNT rope 10, holding mechanism 20, and housing 30 in Embodiment 1. The cartridges C are arranged in a matrix (vertically and horizontally) when viewed from above (see Figure 6(b)). In Figure 6, the cartridges C are arranged planarly in a 4x7 grid.

[0096] The mechanical energy storage unit 6 is equipped with one power generation mechanism 40, which is connected to the holding mechanism rotation shaft 24 of one of the multiple cartridges C via a power generation mechanism connecting member 26.

[0097] The interlocking mechanism 80 in the mechanical energy storage unit 6 is a timing belt that interlocks the holding mechanism rotating shafts 24 (and consequently the SWCNT ropes 10) in the two cartridges C. The timing belt may also be a toothed belt, in which case gears are placed on the holding mechanism rotating shafts 24. Furthermore, the interlocking mechanism 80 may interlock three or more holding mechanism rotating shafts 24 (and consequently the SWCNT ropes 10). The interlocking mechanism 80 may consist of a single component or multiple components.

[0098] The mechanical energy storage unit 6 may also include a substrate, housing, support members, etc., for stably arranging or fixing the multiple cartridges C and the interlocking mechanism 80.

[0099] The mechanical energy storage body 6 according to Embodiment 6 differs from the mechanical energy storage body 1 according to Embodiment 1 in that it comprises a plurality of SWCNT ropes and an interlocking mechanism. However, because it also comprises SWCNT ropes 10 and a holding mechanism 20, it is a mechanical energy storage body that can safely store mechanical energy at high density, similar to the mechanical energy storage body 1.

[0100] Furthermore, the mechanical energy storage body 6 according to Embodiment 6 includes a plurality of SWCNT ropes 10 as SWCNT ropes, and further includes an interlocking mechanism 80 that links the twisting states of the SWCNT ropes 10. Therefore, the mechanical energy storage body 6 according to Embodiment 6 can store a larger amount of mechanical energy by increasing the number of SWCNT ropes 10, making it possible to handle large amounts of energy.

[0101] Since the mechanical energy storage body 6 according to Embodiment 6 has basically the same configuration as the mechanical energy storage body 1 according to Embodiment 1, it has the corresponding effect among the effects of the mechanical energy storage body 1.

[0102] [Embodiment 7] Figure 7 is a diagram illustrating the mechanical energy storage body 7 according to Embodiment 7. Figure 7(a) is a front view of the mechanical energy storage body 7, and Figure 7(b) is a top view of the mechanical energy storage body 7. In Figure 7(a), of the multiple SWCNT ropes 10, holding mechanisms 20, housings 30, and pinions 94, only the one on the left side of the drawing is labeled with a reference numeral. In Figure 7(b), of the multiple holding mechanisms 20 and pinions 94, only the one in the upper left of the drawing is labeled with a reference numeral, and of the multiple cartridges C and racks 92a and 92b, only the one at the top of the drawing is labeled with a reference numeral. In Figure 7(b), the pinion 94 on the back of rack 92b is shown with a dashed line.

[0103] The mechanical energy storage body 7 according to Embodiment 7 has basically the same configuration as the mechanical energy storage body 6 according to Embodiment 6, but the configuration of the interlocking mechanism is different.

[0104] The interlocking mechanisms 90a and 90b in the mechanical energy storage unit 7 have multiple racks 92a and 92b and multiple pinions 94 (a so-called rack and pinion mechanism). The pinions 94 are mounted on the outside of the housing 30 on the holding mechanism rotation shaft 24 of the holding mechanism 20. The racks 92a and 92b are designed to mesh with the pinions 94. The multiple racks 92a and 92b are connected at their respective ends.

[0105] The rack 92a in the interlocking mechanism 90a and the rack 92b in the interlocking mechanism 90b are positioned to sandwich the pinion 94. Therefore, when the pinion 94 is rotated (when storing and releasing mechanical energy), the interlocking mechanism 90a and the interlocking mechanism 90b move in opposite directions.

[0106] The racks 92a, 92b and pinion 94 may be made of metal material, but depending on the size and output of the mechanical energy storage body 7, they may also be made of microfabricated semiconductor material.

[0107] The mechanical energy storage unit 7 is equipped with two interlocking mechanisms 90a and 90b primarily to enhance the reliability of its operation. For this reason, the mechanical energy storage unit 7 can function even when it is equipped with only interlocking mechanism 90a or only interlocking mechanism 90b.

[0108] Although the configuration of the interlocking mechanism of the mechanical energy storage body 7 according to Embodiment 7 differs from that of the mechanical energy storage body 6 according to Embodiment 6, it is equipped with an SWCNT rope 10 and a holding mechanism 20, and therefore, like the mechanical energy storage body 6, it is a mechanical energy storage body that can safely store mechanical energy at high density.

[0109] Since the mechanical energy storage body 7 according to Embodiment 7 has basically the same configuration as the mechanical energy storage body 6 according to Embodiment 6, it has the corresponding effect among the effects of the mechanical energy storage body 6.

[0110] [Examples] The inventors of this invention actually manufactured SWCNT rope, the most important component in a mechanical energy storage system, and conducted various tests. The manufacturing and testing of the SWCNT rope are described below.

[0111] First, let's describe the materials used in the examples. As single-walled carbon nanotubes, we used "EC2.0" with a diameter of approximately 2.0 nm and "EC1.5" with a diameter of approximately 1.5 nm, procured from Meijo Nanocarbon Co., Ltd. These were manufactured using the MEIJO eDIPS method, a type of gas-phase fluid flow method. For the thermoplastic polyurethane (TPU), we used "Elastran® S80A10," which was procured from BASF Japan Ltd. For the pellets of short-molecule polystyrene (PSS) with an average molecular weight Mw of 800-5,000 amu and long-molecule polystyrene (PSL) with an average molecular weight Mw of 300,000 amu, we used materials purchased from Polysciences, Inc. (USA). All solvents described below were analytical-grade products purchased directly from Fujifilm Wako Pure Chemical Industries, Ltd. As a cyanoacrylate adhesive, we used "Konishi Bond® Aron Alpha® Super Jelly®," purchased from Konishi Corporation.

[0112] 1. Manufacturing of SWCNT ropes made from single-walled carbon nanotubes Figure 8 is a photograph showing the manufacturing process of a SWCNT rope made of single-walled carbon nanotubes in an example. Figure 8(a) is a photograph of an aggregate of single-walled carbon nanotubes, and Figure 8(b) is a photograph showing the twisting of a filamentous material made of single-walled carbon nanotubes.

[0113] First, we investigated the portion of the SWCNT rope structure that consists of single-walled carbon nanotubes. The method for manufacturing an SWCNT rope consisting solely of single-walled carbon nanotubes is as follows: First, some single-walled carbon nanotubes were grasped and pulled out using tweezers from a lump of single-walled carbon nanotubes (see Figure 8(a)) to obtain a thread-like material (SWCNT strand) consisting of single-walled carbon nanotubes.

[0114] Next, a few drops of acetone were added to the obtained filamentous material and allowed to permeate, and the material was twisted several times by hand to produce SWCNT rope (see Figure 8(b)). The SWCNT rope produced in this way is called "y-rope".

[0115] In addition, separate from the above, SWCNT rope was manufactured by dropping a solvent (acetone, ethanol, or water) onto an aggregate of single-walled carbon nanotubes, sandwiching it between PTFE sheets, applying mechanical pressure with a roller, drying it, and then dropping toluene onto it and twisting it (roll method). SWCNT rope manufactured by this method is called "r-rope".

[0116] SWCNT ropes were also produced by a dispersion method, in which aggregates of single-walled carbon nanotubes were dispersed in a solvent (acetone, toluene, H2O2, etc.), filtered and dried, and then twisted while adding toluene dropwise. SWCNT ropes produced by this method are called "d-rope".

[0117] 2. Gravimetric energy density of SWCNT rope made of single-walled carbon nanotubes Figure 9 is a photograph showing the measurement of the gravimetric energy density of the SWCNT rope in the embodiment. Figure 9(a) is a photograph showing the entire measuring apparatus, and Figure 9(b) is a photograph showing the SWCNT rope during measurement. Figure 10 is a bar graph showing the gravitational energy density (GED) of a SWCNT rope made of single-walled carbon nanotubes in the example. The vertical axis of the graph in Figure 10 represents the gravitational energy density (unit: MJ / kg).

[0118] The mechanical energy that can be stored in the SWCNT rope described above was measured as gravimetric energy density (GED). First, the method and results of measuring gravimetric energy density will be explained.

[0119] To calculate the gravitational energy density due to the twisting of an SWCNT rope, it is necessary to measure the tension F and torque T resulting from twisting an SWCNT rope of initial length L0 and mass m, as shown in equation (1) below. The tension F was measured using Shimadzu Corporation's small benchtop testing machine EZ Test® EZ-LX (hereinafter simply referred to as "the testing machine") and recorded using Shimadzu Corporation's TRAPEZIUM X (see Figure 9). The maximum load of the load cell set in the testing machine was 500 N.

[0120] In the example, an eye hook with a 0.5 mm opening was attached to the testing machine, and the SWCNT rope was fixed to the eye hook using a cyanoacrylate adhesive. The length of the SWCNT rope (sample) used for measuring the gravimetric energy density was 20-30 mm, and the distance between the eye hooks was 5 mm. The twisting speed was set to 110 rpm.

[0121] Furthermore, using the same testing machine structure as that used to measure tension F, torque T was measured in parallel with tension F. Torque T was measured using an analog torque gauge (ATG045CN, Tohnichi Manufacturing Co., Ltd.) connected to the lower eye hook, and the displacement of the analog torque gauge was recorded using a laser displacement meter (sensor head: IL-S065, setting support software: LK-Navigator 2, both from Keyence Corporation). In addition, recording was performed using a high-speed camera (EX-100PRO, Casio Computer Co., Ltd.) to confirm the torque characteristics (double check).

[0122] The gravimetric energy density (GED) for each number of turns can be evaluated using the following formula (1). Note that "n" is the number of turns in the SWCNT rope, and "F" is the number of turns in the SWCNT rope. n " is the tension when the number of turns is n, and "T n " is the torque when the number of turns is n, and "ΔL n " is the difference in length when the number of turns changes from n-1 to n, and "Δφ" is equal to 2π.

number

[0123] In the examples, the gravimetric energy density was measured for the following ropes: "y-rope(d=1.5nm)" which was manufactured using single-walled carbon nanotubes with a diameter of 1.5 nm; "y-rope(d=2.0nm)" which was manufactured using single-walled carbon nanotubes with a diameter of 2.0 nm; "r-rope(H2O)" which was manufactured using water under pressure; "r-rope(acetone)" which was manufactured using acetone under pressure; "r-rope(ethanol)" which was manufactured using ethanol under pressure; and "d-rope(toluene)" which was manufactured using toluene for dispersion.

[0124] As a result, y-rope (d=1.5nm) showed the highest gravimetric energy density (see Figure 10). Therefore, y-rope (d=1.5nm) was used as the basis for subsequent tests (modification of SWCNT ropes). In the following description, y-rope (d=1.5nm) will simply be referred to as "y-rope" or "y-rope".

[0125] 3. Manufacturing of modified SWCNT rope Next, we attempted to modify SWCNT ropes made of single-walled carbon nanotubes. Specifically, we added thermoplastic resin to the single-walled carbon nanotubes, deposited carbon and sulfur, and irradiated them with microwaves.

[0126] The modification of SWCNT ropes by adding thermoplastic resin (in other words, the production of SWCNT ropes mainly composed of single-walled carbon nanotubes and thermoplastic resin) was carried out as follows. First, some single-walled carbon nanotubes were grasped and pulled out from a lump of single-walled carbon nanotubes using tweezers to obtain a filamentous material (SWCNT strand) made of single-walled carbon nanotubes.

[0127] Next, 100 μl of an acetone solution of thermoplastic resin (0.54 mg / ml) was added to the obtained filamentous material, and it was twisted several times by hand. Subsequently, the twisted filamentous material was dried under reduced pressure at 180°C for 1 hour, then sealed in a glass tube under vacuum (0.06~0.4 Pa), and irradiated with microwaves at 200 W for 5 seconds.

[0128] Regarding the SWCNT ropes manufactured as described above, those manufactured using thermoplastic polyurethane (TPU) are referred to as "y-rope(TPU)", those manufactured using short-molecular-weight polystyrene (PSS) are referred to as "y-rope(PSS)", and those manufactured using long-molecular-weight polystyrene (PSL) are referred to as "y-rope(PSL)". Their diameters were typically 30-100 μm, and their lengths were 20-30 mm.

[0129] The modification of SWCNT ropes by carbon deposition was carried out using JEOL Ltd.'s JEC-530 Auto Carbon Coater. The y-rope to be deposited was positioned 25 mm from the carbon rod. Multiple 10-second cycles were performed to heat the carbon rod to the carbon evaporation temperature, thereby depositing a thin carbon film onto the y-rope. The SWCNT rope produced in this manner is called "y-rope(C)". Furthermore, an SWCNT rope that has been irradiated with microwaves after carbon deposition using the same method as in the case of modification by adding thermoplastic resin is called "y-rope(C+MW)".

[0130] The modification of SWCNT ropes by carbon and sulfur deposition was carried out by placing 1 μl of S / CS2 solution (0.05 or 0.5 mg / ml) in a glass tube, completely evaporating the CS2, and then placing y-rope(C) in the same glass tube and sealing it at low pressure (<1 Pa) and 300°C for 1 hour. The SWCNT rope produced in this manner is called "y-rope(C+S)".

[0131] The modification of the SWCNT rope by microwave irradiation was carried out by irradiating the y-rope with microwaves in the same manner as the modification of the SWCNT rope by adding thermoplastic resin. The SWCNT rope manufactured in this way is called "y-rope(MW)".

[0132] 4. Gravimetric energy density of modified SWCNT rope Figure 11 is a graph showing the performance of the modified SWCNT rope in the embodiment. Figure 11 is a graph showing the gravitational energy density (GED) of the modified SWCNT rope, with the vertical axis representing gravitational energy density (unit: MJ / kg) and the horizontal axis representing torsional strain ε. Figure 12 is a graph showing the gravimetric energy density and power density of major energy storage technologies. In the graph in Figure 12, the vertical axis represents power density (unit: W / kg), and the horizontal axis represents gravimetric energy density (unit: MJ / kg on the top side, unit: Wh / kg on the bottom side).

[0133] The gravitational energy density (GED) was measured for the modified SWCNT ropes described above. The measurement method was the same as for SWCNT ropes made of single-walled carbon nanotubes, so the explanation is omitted. In this measurement, the diameter of each SWCNT rope was set to 30 ± 4 μm.

[0134] As a result, it was confirmed that SWCNT ropes with added thermoplastic resin tended to have a higher gravimetric energy density (see Figure 11). In particular, y-rope(TPU) showed a maximum gravimetric energy density of 2.1±0.07 MJ / kg at a torsional strain ε=1.2, and an average gravimetric energy density of 1.38±0.48 MJ / kg. Furthermore, it was confirmed that y-rope(TPU) released up to 90±2% of its energy in 1.1 seconds. The power density calculated from this was 1.85±0.43 MW / kg.

[0135] Here, we compare the gravimetric energy density and power density of known major energy storage technologies and y-rope(TPU). From the standpoint of gravimetric energy density and power density, y-rope(TPU) surpasses the performance of known energy storage technologies that are recyclable (repeated storage and release of energy), and can be said to have performance close to that of explosives or fuel (see Figure 12). For example, y-rope(TPU) has a gravimetric energy density more than three times that of a lithium-ion secondary battery (Li-ion battery) with a gravimetric energy density of approximately 0.72 MJ / kg, and moreover, it has the advantage of not having the risk of ignition or explosion due to chemical reactions.

[0136] The results above confirm that it is possible to store mechanical energy at high density by using SWCNT ropes, which are mainly composed of single-walled carbon nanotubes and thermoplastic resins.

[0137] 5. Other tests related to SWCNT ropes Figure 13 is a graph showing the temperature dependence of the performance of y-rope(TPU) in the example. In the graph of Figure 13, the vertical axis represents normalized gravimetric energy density (unit: au), and the horizontal axis represents temperature (unit: °C). In the graph of Figure 13, the maximum gravimetric energy density at 25 °C is normalized. The data in the graph of Figure 13 are shown as the mean ± standard deviation (3 trials) of y-rope(TPU). The dashed line L1 is an auxiliary line indicating that the gravimetric energy density of y-rope(TPU) is independent of temperature.

[0138] Figure 14 is a graph showing the repeatability characteristics of the y-rope(TPU) performance in the embodiment. In the graph in Figure 14, the vertical axis represents the normalized gravitational energy density (unit: au), and the horizontal axis represents the number of cycles (described later). In addition, a graph showing the time dependence of the gravitational energy density for the first few cycles is inserted in the lower center of Figure 14. In this inserted graph, the vertical axis represents the normalized gravitational energy density (unit: au), and the horizontal axis represents time (unit: seconds). In Figure 14, the gravitational energy density is normalized when the rotational speed is 110 rpm and the maximum torsional strain ε = 0.6. The data in Figure 14 is shown as the mean ± standard deviation (3 trials) of the y-rope(TPU). The dashed line L2 is an auxiliary line showing that the gravitational energy density of the y-rope(TPU) does not depend on the number of cycles.

[0139] Tests were conducted on the temperature dependence and cyclic characteristics of y-rope(TPU). For the measurement of temperature dependence, the temperature dependence of the maximum gravimetric energy density of y-rope(TPU) at a torsional strain ε=0.6 was measured. Specifically, a sample of y-rope(TPU) was heated from 298K and then cooled, and three consecutive cycles consisting of torsion and release were performed at a predetermined temperature. As a result, it was confirmed that y-rope(TPU) exhibits stable energy storage capacity from -60°C to 100°C (see Figure 13).

[0140] Furthermore, in measuring the repeatability characteristics, y-rope(TPU) was subjected to 100 consecutive cycles consisting of twisting and untwisting. As a result, it was confirmed that y-rope(TPU) exhibited good repeatability characteristics up to 100 cycles (see Figure 14). In addition, it was confirmed that y-rope(TPU) exhibited good repeatability characteristics up to 500 cycles.

[0141] Although the present invention has been described above based on the embodiments described above, the present invention is not limited to the embodiments described above. It can be implemented in various forms without departing from the spirit of the invention, and for example, the following modifications are also possible.

[0142] (1) The positions, sizes, shapes, and numbers of each component described in the above embodiments and shown in the drawings are illustrative examples and can be changed within the scope that does not impair the effects of the present invention.

[0143] (2) The unique features of each of the above embodiments can be combined with each other, provided there are no particular inhibiting factors. For example, the SWCNT rope 11 in Embodiment 2 has a structure in which multiple single ropes 10a, which are mainly composed of single-walled carbon nanotubes and thermoplastic resin, are bundled together, but the SWCNT rope 11 described above can also be used in other embodiments.

[0144] (3) In each of the above embodiments, each mechanical energy storage unit is equipped with a power generation mechanism 40, but the present invention is not limited thereto. The mechanical energy storage unit of the present invention does not need to be equipped with a power generation mechanism. In this case, the mechanical energy storage unit can be used for applications that utilize the stored mechanical energy as mechanical energy (rotational force). Furthermore, the mechanical energy storage unit can be used in connection with an energy conversion mechanism (a mechanism that converts mechanical energy as rotational force into other types of energy) that is separate from the mechanical energy storage unit.

[0145] (4) The configuration of the ratchet mechanism 22 in the holding mechanism 20 described in Embodiment 1 above is illustrative. The holding mechanism in the mechanical energy storage body of the present invention may have a ratchet mechanism with a different configuration from the ratchet mechanism 22. Furthermore, the holding mechanism in the mechanical energy storage body of the present invention may store mechanical energy based on the twisted state of the SWCNT rope by a mechanism different from the ratchet mechanism.

[0146] (5) In embodiments 6 and 7 described above, the cartridges C are arranged planarly in a 4x7 grid, but the present invention is not limited thereto. The number and arrangement of the cartridges C described above are illustrative examples. For example, if the cartridges are arranged in a 30x40 grid, it is possible to store mechanical energy using 1,200 SWCNT ropes. The cartridges may also be stacked perpendicular to the grid. For example, if 30x40 cartridges are stacked in 10 layers, it is possible to store mechanical energy using 12,000 SWCNT ropes. Furthermore, multiple sets of cartridges arranged in grids or stacks may be linked together. For example, by linking a set of 10 stacks of 30x40 cartridges in a 10x10x10 grid, it is possible to store mechanical energy using 12 million SWCNT ropes. Since the SWCNT rope, which is the core of the mechanical energy storage body of the present invention, is thin and light, it is possible to prevent excessive size even when a large number of cartridges are arranged.

[0147] (6) In embodiments 6 and 7 described above, there was one power generation mechanism 40, but the present invention is not limited thereto. The number of power generation mechanisms in the mechanical energy storage body of the present invention may be multiple. In particular, when assemblies of cartridges arranged and stacked as described in (5) above are further connected, a power generation mechanism may exist for each unit of the assembly. Furthermore, the power generation mechanism does not have to be directly connected to a specific cartridge, but may be connected to the cartridge (and by extension, the SWCNT rope) via a link mechanism or the like.

[0148] (7) In embodiments 6 and 7 described above, a holding mechanism 20 exists for each cartridge C, but the present invention is not limited thereto. One holding mechanism may exist for each of multiple cartridges. In particular, when an assembly of cartridges arranged and stacked as described in (5) above is further connected, a holding mechanism may exist for each unit of the assembly. Furthermore, the holding mechanism does not have to be located as part of a specific cartridge, and may be connected to the cartridge (and by extension, the SWCNT rope) via a link mechanism or the like.

[0149] (8) The power generation mechanism in the mechanical energy storage body of the present invention may include not only a rotary type generator but also a linear type generator. [Explanation of Symbols]

[0150] 1,2,3,4,5,6,7…Mechanical energy storage unit, 10,11…SWCNT rope, 10a…Single rope, 12…First end, 14…Second end, 20…Holding mechanism, 22…Ratchet mechanism, 22a,22b…Disc-shaped member, 24…Holding mechanism rotating shaft, 26…Power generation mechanism connecting member, 30,30a…Housing, 32…Rope fixing member, 34…Orientation changing member, 40…Power generation mechanism, 42…Power generation mechanism rotating shaft, 50…Main rotating shaft, 52…Sub-rotating shaft, 54…Rotational force transmission mechanism, 60…Rope folding member, 70…Partition member, 80,90a,90b…Interlocking mechanism, 92a,92b…Rack, 94…Pinion, C…Cartridge

Claims

1. A SWCNT rope having single-walled carbon nanotubes and thermoplastic resin as its main components, and having a first end and a second end, A mechanical energy storage body characterized by comprising a holding mechanism that holds mechanical energy based on the twisted state of the SWCNT rope.

2. The mechanical energy storage body according to claim 1, characterized in that the thermoplastic resin is thermoplastic polyurethane.

3. The mechanical energy storage body according to claim 1, further comprising a housing for storing the SWCNT rope.

4. The mechanical energy storage body according to claim 3, characterized in that the SWCNT rope has its first end fixed to the housing and its second end connected to the holding mechanism.

5. The mechanical energy storage body according to claim 4, characterized in that the SWCNT rope has a structure in which a plurality of single ropes, each mainly composed of the single-walled carbon nanotube and the thermoplastic resin, are bundled together.

6. The mechanical energy storage body comprises a plurality of SWCNT ropes as the SWCNT rope, and further comprises a main rotating shaft connected to the holding mechanism, a sub-rotating shaft connected to the second end of the SWCNT rope, and a rotational force transmission mechanism that transmits rotational force between the main rotating shaft and the sub-rotating shaft. The mechanical energy storage body according to claim 4, characterized in that the second end of the SWCNT rope is connected to the holding mechanism via the sub-rotating shaft, the rotational force transmission mechanism, and the main rotating shaft.

7. The mechanical energy storage body according to claim 4, characterized in that the SWCNT rope is housed in the housing in a state having slack, at least in a state in which the mechanical energy held is at its minimum.

8. The mechanical energy storage body according to claim 4, further comprising a rope folding member that causes the SWCNT rope to meander within the housing.

9. The mechanical energy storage body according to claim 4, further comprising a partition member for arranging the SWCNT rope in a spiral shape within the housing.

10. The mechanical energy storage body according to claim 4, characterized in that the holding mechanism has a ratchet mechanism that restricts the rotation direction to a predetermined direction when the mechanical energy is stored in the SWCNT rope, and releases the restriction on the rotation direction when the mechanical energy is released from the SWCNT rope.

11. The mechanical energy storage body according to claim 1, further comprising a power generation mechanism that converts the mechanical energy stored in the SWCNT rope into electrical energy.

12. The mechanical energy storage body according to claim 11, characterized in that the power generation mechanism can generate rotational force using electricity supplied from outside the mechanical energy storage body and store the mechanical energy in the SWCNT rope.

13. The mechanical energy storage body according to claim 11, characterized in that the power generation mechanism has a coreless generator.

14. The mechanical energy storage body according to claim 11, characterized in that the power generation mechanism has an electrostatic generator.

15. The mechanical energy storage body according to claim 11, characterized in that the power generation mechanism is separable from and connectable to the SWCNT rope and the holding mechanism.

16. The mechanical energy storage body according to claim 1, further comprising a plurality of SWCNT ropes as the SWCNT ropes, and an interlocking mechanism for linking the twisted states of the SWCNT ropes.

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