JP2008304045A - Superconductive flywheel system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a superconductive flywheel system utilizing a superconductive coil capable of effectively cooling heat generated by contact rotation even in a case where a rotating body of the flywheel loses thrust force and contact-rotates with a bearing. <P>SOLUTION: The superconductive flywheel system 1 for floating the rotating body 11 up for storing rotational energy by utilizing superconductivity is provided with an outer tank container 7 for keeping the rotating body 11 in a vacuum, a thrust bearing 4 for keeping contact rotation of the rotating body 11, a positional sensor 9 for judging whether the rotation body 11 is floating or not and a vacuum valve 8 for introducing atmospheric air into the outer tank container 7 based on measured result of the positional sensor 9. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a superconducting flywheel system using superconductivity.

In general, what is called a superconducting flywheel system is one that generates a thrust force (levitation force) by a magnetic force acting between a high-temperature superconducting bulk material and a permanent magnet (see, for example, Patent Document 1), and electromagnetic waves generated by a superconducting coil. There is one that generates thrust force (levitation force) by force (for example, see Patent Document 2) or one that utilizes both (for example, see Patent Document 3). In either case, the superconducting technology is applied to float and rotate the rotating body in a non-contact manner. Thus, a superconducting flywheel system is a system that minimizes energy loss and efficiently stores energy. The energy stored in this way is utilized for stabilization of power supply such as power load adjustment and power compensation at the time of power failure.
JP 2003-049836 A JP 2002-005165 A JP 2003-219581 A

  As described above, in the superconducting flywheel system, the rotating body is levitated by applying superconducting technology. For this reason, in order to maintain the superconducting state of the superconducting material used, it is necessary to cool the corresponding part to a cryogenic temperature using a small refrigerator or the like.

  On the other hand, when the superconducting flywheel system loses system power due to a power failure or the like, it converts the rotational energy of the flywheel into electrical energy and releases it. Using the converted electrical energy, power compensation is performed.

  Here, if the system power does not recover while compensating for the power, the superconducting flywheel system will gradually reduce the power generation capacity. Along with this, the refrigeration system is also stopped. When the refrigeration system stops, the temperature of the superconducting part gradually increases. If the temperature of the superconducting part continues to rise, the superconducting state is broken (quenched). As a result, the rotating body loses levitation force. When the levitation force is lost, the rotating body lands on the thrust auxiliary bearing. After landing, contact rotation is performed on the thrust auxiliary bearing until energy release to the outside is completed. Such a phenomenon can occur not only at the time of a power failure, but also at the time of trouble of the superconducting coil power supply or the refrigerator system.

  Thrust auxiliary bearings are designed to reduce rolling friction. However, in general, a rotating body of a flywheel is heavy (for example, about 25 tons in one design example of a system having a storage energy of 50 kWh). For this reason, the frictional heat generated in proportion to the product of rolling friction and weight is an amount that cannot be ignored. Furthermore, a flywheel system arrange | positions a rotary body in a vacuum in order to reduce the windage loss at the time of energy storage (at the time of rotation). For this reason, there is no atmosphere that plays the role of a heat sink. Therefore, cooling of the thrust auxiliary bearing is not easy.

  Due to these factors, if the rotating body continues rotating on the thrust auxiliary bearing, the allowable temperature of the thrust auxiliary bearing may be exceeded and the thrust auxiliary bearing may be burned.

  Accordingly, an object of the present invention is to provide a superconducting fly using a superconducting coil that can effectively cool the heat generated by contact rotation even when the rotating body of the flywheel loses thrust force and rotates in contact with the bearing. To provide a wheel system.

  A superconducting flywheel system according to an aspect of the present invention is a superconducting flywheel system in which a rotating body for storing rotational energy is levitated using superconductivity, and a container for maintaining the rotating body in a vacuum. A thrust bearing means for bringing the rotating body into contact with the rotating body and maintaining the rotation of the rotating body when the rotating body is not floating; and a determining means for determining whether or not the rotating body is levitated; If the determination result based on the determination means is negative, an air introduction means for introducing air into the container is provided.

  According to the present invention, a superconducting flywheel system using a superconducting coil capable of effectively cooling heat generated by contact rotation even when a rotating body of a flywheel loses thrust force and rotates in contact with a bearing. Can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram showing a configuration of a superconducting flywheel system 1 according to a first embodiment of the present invention. In the drawings, the same portions are denoted by the same reference numerals, detailed description thereof is omitted, and different portions are mainly described. In the following embodiments, the same description is omitted.

  The superconducting flywheel system 1 includes a rotating body (flywheel) 11, a superconducting thrust bearing 2, a radial bearing 3, a thrust auxiliary bearing 4, a radial auxiliary bearing 5, a generator motor 6, an outer tank container 7, A vacuum valve 8 and a position sensor 9 are provided.

  The rotating body 11 includes a flywheel main body 11a and a rotor shaft 11b. The flywheel main body 11a is attached to the rotor shaft 11b. The rotating body 11 stores rotational energy.

  The superconducting thrust bearing 2 includes a superconducting coil 2a, a fixed-side thrust bearing magnetic body 2b, a rotating-side thrust bearing magnetic body 2c, and a small refrigerator 2d. The superconducting thrust bearing 2 gives a levitation force to the rotating body 11.

  Superconducting coil 2a generates an electromagnetic force for applying a levitation force to rotating body 11. The fixed-side thrust bearing magnetic body 2b and the rotation-side thrust bearing magnetic body 2c are magnetic bodies for converting the electromagnetic force generated by the superconducting coil into a levitation force. The fixed-side thrust bearing magnetic body 2b is installed on the outer tank container 7 side. The rotation side thrust bearing magnetic body 2c is installed on the rotation body 11 side. The small refrigerator 2d is a device for cooling the superconducting coil 2a.

  The radial bearing 3 is a component for controlling the radial position of the rotating shaft of the rotating body 11.

  With the superconducting thrust bearing 2 and the radial bearing 3, the rotating body 11 maintains its rotation without contact. Thereby, the rotation loss of the rotary body 11 can be reduced.

  The thrust auxiliary bearing 4 and the radial auxiliary bearing 5 are provided so that the contact rotation can be safely maintained in an abnormal state where the non-contact floating of the rotating body 11 cannot be maintained. The thrust auxiliary bearing 4 is provided to maintain the contact rotation of the rotating body 11 mainly in the vertical direction. The radial auxiliary bearing 5 is provided to maintain the contact rotation of the rotating body 11 mainly in the radial direction. The thrust auxiliary bearing 4 and the radial auxiliary bearing 5 are, for example, ball bearings.

  The generator motor 6 is a device for converting the rotational energy of the rotating body 11 into electric energy.

  The position sensor 9 measures the position of the rotating body 11 in the vertical direction (axial direction). The position sensor 9 is a measuring device for detecting an abnormal state where the non-contact floating of the rotating body 11 cannot be maintained. The position sensor 9 detects an abnormality when the rotating body 11 has landed on the thrust auxiliary bearing 4 due to the losing force of the rotating body 11. The position sensor 9 determines whether or not the rotating body 11 is floating (or whether or not it is in contact with the thrust auxiliary bearing 4) based on a change in the position of the rotating body 11.

  The outer tank container 7 is a container for maintaining the rotating body 11 in a vacuum state. Thereby, the rotary body 11 can reduce the windage loss at the time of energy storage (at the time of rotation). The outer tub container 7 includes a rotating body 11, a superconducting thrust bearing 2, a radial bearing 3, a thrust auxiliary bearing 4, a radial auxiliary bearing 5, a generator motor 6, a position sensor 9, and the like in a vacuum state.

  The vacuum valve 8 is a valve for introducing air or the like into the outer tank container 7 maintained in a vacuum state. The vacuum valve 8 is provided in the lower part of the outer tank container 7.

  A path through which air or the like introduced from the vacuum valve 8 flows toward the thrust auxiliary bearing 4 is formed inside the outer tank container 7. Accordingly, the air or the like introduced from the vacuum valve 8 is guided to the vicinity of the thrust auxiliary bearing 4 along the flow f1. Thereby, the air flows so as to be blown to the thrust auxiliary bearing 4.

  Next, in the superconducting flywheel system 1 configured as described above, an operation at the time of an abnormality where the non-contact floating of the rotating body 11 cannot be maintained will be described.

  The rotating body 11 loses its levitation force due to a power failure or a trouble with the superconducting coil power supply or the refrigerator system. When the rotator 11 loses the levitation force, it lands on the thrust auxiliary bearing 4. Thereafter, the rotating body 11 maintains contact rotation on the thrust auxiliary bearing 4. At this time, the thrust auxiliary bearing 4 is overheated by frictional heat generation with the rotating body 11.

  If the position sensor 9 determines that the rotating body 11 has not floated, it detects an abnormality.

  The vacuum valve 8 is opened by the detection of the position sensor 9. When the vacuum valve 8 is opened, the atmosphere is introduced into the outer tank container 7 from the outside.

  The atmosphere introduced into the outer tub container 7 radiates heat from the heated thrust auxiliary bearing 4 by acting as a heat sink. Moreover, the air introduced into the outer tub container 7 is cooled below the outside air temperature by the effect of adiabatic expansion. Furthermore, the air introduced into the outer tank vessel 7 flows along the flow f1, thereby forcibly air-cooling the thrust auxiliary bearing 4.

  According to the present embodiment, heat generated by contact rotation of the rotating body 11 on the thrust auxiliary bearing 4 can be efficiently cooled. Thereby, since the temperature rise of the thrust auxiliary bearing 4 can be suppressed, seizure of the thrust auxiliary bearing 4 can be prevented even during the contact rotation of the rotating body 11. Therefore, the highly reliable superconducting flywheel system 1 can be provided.

(Second Embodiment)
The superconducting flywheel system 1 according to the second embodiment is a modification of the first embodiment, and is the same except that the amount of the vacuum valve 8 introduced into the atmosphere is adjusted.

  A method for adjusting the amount of air introduced into the vacuum valve 8 will be described.

  In the superconducting flywheel system 1, the heat generation after the rotating body 11 has landed on the thrust auxiliary bearing 4 continues until the rotation of the rotating body 11 stops. Therefore, the time t1 from when the rotating body 11 cannot obtain the levitation force (or after the rotating body 11 starts contact rotation on the thrust auxiliary bearing 4) until the rotating body 11 stops rotating is estimated. To do.

  The vacuum valve 8 adjusts the conductance so that the state in which the atmosphere is continuously introduced is a time t2 slightly longer than the time t1. Time t2 is the time until the inside of the outer layer container 7 changes from a vacuum state to an atmospheric state. This is because the cooling effect of the thrust auxiliary bearing 4 can be obtained when the rotating body 11 is rotating. That is, to obtain a cooling effect by adiabatic expansion when the thrust auxiliary bearing 4 generates heat. Further, the thrust auxiliary bearing 4 is forcibly air-cooled by the atmosphere introduced from the vacuum valve 8.

  In forced air cooling, the greater the amount of air introduced, the higher the cooling efficiency. This is because the wind speed of the air introduced from the vacuum valve 8 becomes weak immediately before the introduction of the atmosphere into the outer layer container 7 (the state where the inside of the outer layer container 7 is close to atmospheric pressure). Therefore, the cooling effect is higher when the atmospheric introduction time t2 is set a little longer than the rotation time t1 of the rotating body 11.

  According to the present embodiment, in addition to the operational effects of the first embodiment, the temperature of the thrust auxiliary bearing 4 can be more effectively suppressed by adjusting the amount of the vacuum valve 8 that is introduced into the atmosphere and the like. it can. Therefore, the superconducting flywheel system 1 with higher reliability can be provided.

(Third embodiment)
FIG. 2 is a configuration diagram showing a configuration of a superconducting flywheel system 1A according to the third embodiment.

  The superconducting flywheel system 1A has the same configuration as the superconducting flywheel system 1 shown in FIG. 1 except that a heat exchanger (cooler) 10 is provided.

  The heat exchanger 10 is attached between the vacuum valve 8 and the outer tank container 7. The atmosphere introduced from the vacuum valve 8 is cooled by the heat exchanger 10. As a result, the thrust auxiliary bearing 4 is forcibly air-cooled by the cooled atmosphere along the flow f2.

  According to the present embodiment, in addition to the operational effects of the first embodiment, the thrust auxiliary bearing 4 can be cooled by the cooled air or the like by lowering the temperature of the introduced air or the like by the heat exchanger 10. it can. Thereby, especially the temperature rise of the thrust auxiliary bearing 4 can be suppressed more efficiently. Therefore, it is possible to provide a superconducting flywheel system 1A with higher reliability.

  In each embodiment, the path for flowing the air introduced from the vacuum valve 8 toward the thrust auxiliary bearing 4 may be formed in any way. For example, as shown in FIG. 3, a nozzle 21 that directly blows against the thrust auxiliary bearing 4 may be provided. By providing a narrow path such as a nozzle, the flow velocity of the atmosphere or the like can be increased. Thereby, the cooling effect of the thrust auxiliary bearing 4 can be made higher. Further, as shown in FIG. 4, a member 22 that is a stack of dish-shaped members may be disposed in the vicinity of the outlet on the outer layer container 7 side of the vacuum valve 8. At this time, the air introduced from the vacuum valve 8 blows through the space between the dish shapes of the members 22. By passing through a narrow path by the member 22, the flow velocity of the atmosphere or the like can be increased.

  In the second embodiment, the heat exchanger 10 according to the third embodiment may be provided. With such a configuration, the combined effects of the second embodiment and the third embodiment can be obtained.

  In the second embodiment, the amount of air introduced by the vacuum valve 8 is adjusted in advance, but may be changed according to time and circumstances. The conductance of the vacuum valve 8 may be automatically adjusted according to the rotation speed of the ball provided in the thrust auxiliary bearing 4. This automatic conductance adjustment based on the rotational speed may be performed mechanically or electrically. When electrically performed, a measuring device for measuring the rotation speed of the ball may be provided, and the conductance adjustment may be computer-controlled based on the measurement result of the measuring device.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the structure of the superconducting flywheel system which concerns on the 1st Embodiment of this invention. The block diagram which shows the structure of the superconducting flywheel system which concerns on the 3rd Embodiment of this invention. The block diagram which shows the structure of the superconducting flywheel system which concerns on the 1st modification of the 1st Embodiment of this invention. The block diagram which shows the structure of the superconducting flywheel system which concerns on the 2nd modification of the 1st Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Superconducting flywheel system, 2 ... Superconducting thrust bearing, 2a ... Superconducting coil, 2b ... Fixed thrust bearing magnetic body, 2c ... Rotating side thrust bearing magnetic body, 2d ... Small refrigerator, 3 ... Radial bearing, 4 ... Thrust Auxiliary bearing, 5 ... radial auxiliary bearing, 6 ... generator motor, 7 ... outer tank container, 8 ... vacuum valve, 9 ... position sensor, 10 ... heat exchanger, 11 ... rotating body, 11a ... flywheel body, 11b ... rotor axis.

Claims (7)

In a superconducting flywheel system that uses superconductivity to float a rotating body for storing rotational energy,
A container for maintaining the rotating body in a vacuum;
When the rotating body is not floating, thrust bearing means for contacting the rotating body and maintaining the rotation of the rotating body;
Determination means for determining whether or not the rotating body is floating;
A superconducting flywheel system comprising: air introduction means for introducing air into the container when the determination result based on the determination means is negative. 2. The superconducting flywheel system according to claim 1, further comprising guiding means for guiding the air introduced by the air introducing means to the thrust bearing means. Radial bearing means for contacting the rotating body and controlling a radial position of a rotating shaft of the rotating body;
2. The superconducting flywheel system according to claim 1, further comprising guiding means for guiding the air introduced by the air introducing means to the radial bearing means. 4. The superconducting flywheel system according to claim 3, wherein the guiding means narrows the path through which the atmosphere introduced by the atmosphere introducing means passes so as to increase the flow velocity. 4. The air introduction unit according to claim 1, wherein the air introduction unit is adjusted so that an air introduction time is longer than a time that is expected in advance until the rotating body stops. 5. Superconducting flywheel system. The air introduction means is adjusted to an air introduction time that is longer than a time that is expected in advance until the rotating body stops, and that can obtain a cooling effect by the air immediately after the rotating body stops. The superconducting flywheel system according to any one of claims 1 to 3. The superconducting flywheel system according to any one of claims 1 to 4, wherein an introduction amount into the container by the air introduction unit is changed based on a rotation speed of the rotating body.

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