JP2008016659A - Permanent current switch, its manufacturing apparatus, and method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology relevant to a current switch which carries out the switching of a permanent current flowing in a supercouductive coil forming high magnetic field, where there is no need to apply ultra high voltage in the manufacturing process for constituting a structure in which voids are hard to remain inside. <P>SOLUTION: The permanent current switch includes a superconductive element wire (31) wound around a bobbin body (20) while being connected to a superconductor, a heater wire (32) which switches the superconductive state/normal conducting state by heating the superconductive element wire (31), a partition wall (33, 34) having a plurality of pores (33h) prepared in the interlayer of the superconductive element wire (31) or the heater wire (32), and a fixing layer (38) which impregnates into a gap between the pores (33h) as well as the superconductive element wire (31) and the heater wire (32) and fixes them. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technical field related to a superconducting coil that forms a high magnetic field by flowing a permanent current, and more particularly to a persistent current switch for turning on and off the permanent current.

  In recent years, high magnetic field type products have been developed for the purpose of high accuracy in MRI (Magnetic Resonance Imaging) apparatuses, which are medical devices. In such a high magnetic field type MRI apparatus, a superconducting coil is employed in the magnetic field generator, and it is a proposition to allow a large current to flow through the superconducting coil in order to generate a high magnetic field. .

  Here, the permanent current switch is connected to such a superconducting coil and turns on and off the current flowing in the coil. This permanent current switch includes a superconducting element wire wound in a coil shape and carrying the same large current as that of the superconducting coil, and a heater wire similarly wound in a coil shape. The permanent current switch forms a circuit connected in series with the superconducting coil, and both are configured to be immersed in cryogenic (4K) liquid helium.

  In such a state, if the heater wire is not heated, the permanent current switch is in the superconducting state, and the current flows through the superconducting coil permanently. On the other hand, if the heater wire generates heat, the permanent current switch is switched to the normal state, and the current flowing through the superconducting coil is cut off.

By the way, in the high magnetic field type MRI, since a large current flows not only in the superconducting coil but also in the permanent current switch as described above, the superconducting wire wound around the permanent current switch is affected by the induced magnetic field. It is necessary to be firmly fixed so as not to move.
As a method for fixing the superconducting wires of the permanent current switch as described above, there is a method of impregnating a resin between the wires wound in a coil shape. According to this resin impregnation method, insulation between the strands wound in a coil shape can be ensured.

  By the way, in the permanent current switch adopting this resin impregnation method, if there is a space (void) in the impregnated resin, the resin cracks from it and the temperature rises locally due to its fracture energy, quenching (unexpected It has been pointed out that this will trigger the transition from superconducting to normal conducting). When this quench occurs, liquid helium is instantly evaporated, causing damage to the internal structure of the MRI apparatus. For this reason, the permanent current switch needs to have a structure in which no space (void) exists in the resin for fixing the superconducting wire.

Thus, the following techniques for obtaining a permanent current switch structure having a structure in which no space (void) exists are known.
That is, as a manufacturing method of the permanent current switch, the permanent current switch is immersed in a liquid resin at atmospheric pressure, depressurized to 0.1 mmHg (13 Pa) or less, and then subjected to ultra high pressure (300 to 600 kg / cm ² ) to form a liquid. A technique that includes a step of impregnating a resin and then heat-curing the liquid resin. And, as a permanent current switch structure, a coiled heater wire is arranged inside the bobbin, a multilayer superconducting element wire is arranged in a coil shape on it, and inorganic fibers (glass fiber etc.) are provided between each layer, and the coil A technique of providing a plurality of vertical grooves so that a liquid resin can be easily impregnated in an FRP cylinder that sandwiches the resin from above and below is known (for example, Patent Document 1).
JP 7-335948 A

  However, according to the above-described known technique, in the step of impregnating and impregnating the liquid resin, a large amount of gas dissolved in the liquid resin is newly generated as voids. If the liquid resin is impregnated between the coils and the inorganic fibers in the state where the voids are mixed in this way, the voids remain in the permanent current switch as they are even if the volume is reduced by subsequent compression at an ultrahigh pressure. Will do.

  If the voids remaining in the resin in this way are aggregated and enlarged, the risk of quenching increases. Furthermore, if facilities that provide ultra-high pressure (there are legal restrictions on type 1 pressure vessels), the equipment cost will increase, and the process of applying ultra-high pressure from the decompression process will involve the movement of a permanent current switch. There is a problem that the manufacturing cost is high, such as being unable to be performed continuously.

  Furthermore, in the structure of the permanent current switch, the inorganic fibers provided between the layers of the superconducting wires wound in multiple layers have a very high flow resistance to spread the liquid resin to every corner. The step of applying an ultrahigh pressure as described above is indispensable. Further, if the voids generated as described above remain and collect using this inorganic fiber as a handle, there is a problem that the strength is lowered and the above-described resin cracks are easily generated.

  The present invention provides a technique that allows a permanent current switch to have a structure in which voids are unlikely to remain and can be impregnated with a resin without going through a process of applying ultrahigh pressure.

In order to solve the above problems, the present invention provides a permanent current switch for controlling a permanent current flowing in a superconductor, wherein the superconductor is connected to the superconductor and wound around a bobbin body, and the superconductor A heater wire that heats the strand to switch the superconducting state / normal conducting state; a partition wall that is provided between the superconducting strand wound around the bobbin body or between the heater wires and has a plurality of pores; And a fixing layer that impregnates and fixes the pores and the gap between the superconducting element wire and the heater wire.
When the invention has such a configuration, the permanent current switch has a structure in which the pressure loss at the time of impregnation with the liquid resin is reduced.

  According to the present invention, a void remaining in a permanent current switch is avoided, a superconducting element wire is firmly fixed, and a quenchless permanent current switch is provided.

Hereinafter, embodiments of a permanent current switch of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the permanent current switch 10 according to this embodiment includes flanges 11 and 11, a bobbin main body 20, a coil part 30, nuts 12 and 12, and spacers 13 and 13. Is done. The permanent current switch 10 shown in FIG. 1 shows the configuration of the permanent current switch 10 in a state before being impregnated with a fixed layer 38 to be described later, and the right half from the center line shows a cross section thereof. Hereinafter, the “permanent current switch 10 in the state before the fixed layer is impregnated” may be referred to as “pre-impregnation switch 10”.

In the permanent current switch 10 configured as described above, the superconducting wire 31 drawn from the coil section 30 is connected to a superconducting coil (superconductor) (not shown) to control the permanent current.
That is, if the permanent current switch 10 and the superconducting coil are immersed together in a refrigerant such as liquid helium, the superconducting state is maintained and the permanent current is not attenuated. However, if the heater wire 32 is energized and heated, the permanent current is Only the coil portion 30 of the switch 10 is switched to the normal conduction state, and the permanent current is attenuated.

The bobbin main body 20 has a winding part 21 and end parts 22 and 22 and is made of a stainless steel material.
The winding part 21 is a part where the coil part 30 is provided on the electrical insulating material 23 (see FIG. 2) coated on the surface thereof. The end portions 22 and 22 are portions to which the flanges 11 and 11 are fixed.

  The flanges 11 and 11 are fixed by nuts 12 and 12 that are inserted from both sides of the bobbin main body 20 and screwed into the end portions 22 and 22. The flanges 11 and 11 configured as described above sandwich and support both ends of the coil portion 30. Note that spacers 13 and 13 to be described later are disposed on the contact surfaces of the flange 11 and the coil portion 30. Here, the flanges 11 and 11 are made of a material such as fiber reinforced resin (FRP), and the nut 12 is made of the same stainless steel material as the bobbin main body 20.

As shown in FIG. 2 in which the section A in FIG. 1 is enlarged, the coil section 30 includes superconducting strands 31 (31L and 31R), heater wires 32, partition walls 33 and 34, and a thermal insulating film 35. A porous layer 36, an outer frame 37, and a fixed layer 38. The coil part 30 configured as described above is a main part of the permanent current switch 10 that is connected to the superconducting coil and controls the permanent current.
Here, the fixing layer 38 is finally fixed by impregnating resin or the like in the gaps between the pores 33h (see FIG. 3) of the partition walls 34 and 33 and the superconducting element wire 31 and the heater wire 32 and fixing them. It is a configured part. However, the pre-impregnation switch 10 is in a state where nothing is impregnated yet in these gaps.

The superconducting strand 31 (31L, 31R) is connected to a superconducting coil (superconductor) and wound around the winding portion 21 of the bobbin main body 20. Here, the first-layer superconducting wire 31L in contact with the bobbin body 20 and the second-layer superconducting wire 31R wound around the outer periphery thereof are non-inductively wound so that the winding directions are opposite to each other. It has become. As described above, since the superconducting wire 31 is non-inductively wound, the generated induction magnetic fields cancel each other, and even if a permanent current flows through the permanent current switch 10, the magnetic field leaks to the outside. Will not.
In the present embodiment, the superconducting wire 31 has a two-layer structure composed of a first layer and a second layer. However, the superconducting wire 31 is not limited to this, and is generalized to an nth layer (n is a natural number). ).

The heater wire 32 is wound around the outer periphery of the layer of the superconducting wire 31, and generates heat when energized from an external power source (not shown), and heats the superconducting wire 31 to be in a superconducting state. To the normal state.
In the present embodiment, the heater wire 32 has a two-layer structure, but is not limited to this, and there is no need for non-inductive winding.

The partition walls 33 and 34 are provided between the layers of the superconducting strand 31 or the heater wire 32 wound around the bobbin main body 20. Furthermore, the partition walls 33 and 34 are provided with a plurality of pores 33h penetrating the surface.
The partition walls 33 (33a, 33b) function as an electrical insulating material, and as shown in FIGS. 3A and 3B, the superconducting strands 31 (31L, 31R) are arranged in a square shape in a sectional view. It makes it easy to wind around.

Furthermore, the pore 33h is provided in the partition walls (33a, 33b) so as to be located at the approximate center of the unit region of the square arrangement. In other words, it can be said that the pores 33 h are provided at an intermediate position of the winding pitch of the superconducting strand 31 or at a valley portion of the superconducting strand 31.
Here, FIG. 3A illustrates an example in which the pores 33h are provided for each column of the superconducting wires 31, and FIG. 3B illustrates an example in which the pores 33h are provided every other column. Yes. The number of holes of these pores 33h is appropriately set in order to adjust the impregnation time of the liquid resin described later.

By arranging the partition wall 33 in this manner, the above-described non-inductive winding is facilitated. Furthermore, it is easy to wind the superconducting wires 31 in a square arrangement in a cross-sectional view. In such a case, the induction magnetic field leaks without being canceled at the end of the coil portion 30 (see FIG. 2). Is prevented from occurring.
By providing the pores 33h in the partition wall 33, the flow resistance of the liquid material before curing of the fixed layer 38 (to be described later) (hereinafter referred to as “liquid material before curing”) is reduced, and the impregnation is promoted. Is done. As a result, the pressure required to impregnate the liquid can be kept low, and for example, it can be impregnated in a short time at 0.93 MPa or less, which can be achieved with a general air compressor.
Further, after the liquid is cured, the partition walls 33, 34, the superconducting element wire 31, and the heater wire 32 are integrated through the pores 33h, and a stronger structure is obtained. Moreover, the peeling which generate | occur | produces between the fixed layer 38 after hardening, the partition walls 33 and 34, the superconducting strand 31, and the heater wire 32 can also be suppressed.

  In the description of the partition wall 33, the description is given on behalf of the one disposed between the layers around which the superconducting wire 31 is wound. However, in the case of the partition wall 34 disposed between the layers around which the heater wire 32 is wound. The same is true even if it is disposed between the superconducting wire 31 and the heater wire 32. Moreover, although it demonstrated demonstrating that the arrangement | sequence in the cross sectional view of the superconducting strand 31 was a square arrangement, it is not limited to this, The case where it is a zigzag arrangement can also be taken.

Returning to FIG. 2, the description will be continued.
The thermal insulating film 35 is provided on the outer periphery of the layer of the heater wire 32, suppresses the heat generated by the heater wire 32 from being transmitted to the outside, and concentrates heat transfer to the superconducting element wire 31 side. It is something to be made. The thermal insulating film 35 is also provided with a large number of pores as described above, but the arrangement position may be random. The large number of pores provided in the heat insulating film 35 has the same effect as that described above to improve the impregnation of the liquid before curing. The impregnation of the pre-curing liquid material in the porous layer 36 disposed between the heat insulating films 35 is improved, and the integrity of the heat insulating film 35 and the porous layer 36 is improved to have a stronger structure. To do.

  The porous layer 36 forms the outermost layer portion of the coil portion 30 of the permanent current switch 10 to be finally formed, and functions to suppress the superconducting element wire 31 and the heater wire 32 against the bobbin body 20. To do. The porous layer 36 is configured by winding a porous sheet such as a glass fiber tape in multiple layers. Further, in relation to the thermal insulating film 35, a part of the fixed layer 38 is formed by alternately winding the thermal insulating film 35 and the porous sheet.

The outer frame 37 is provided on the outer periphery of the portion to become the fixed layer 38 and functions when the liquid material before curing is impregnated. The impregnated liquid material is cured to form the fixed layer 38. It will be removed after. The outer frame 37 is made of a member such as a Teflon (registered trademark) sheet.
An injection gap 37G is provided on both end faces of the outer frame 37 (only one end face is shown in FIG. 2), from which the pre-curing liquid material is injected.
That is, the injection gap 37 </ b> G is configured such that the outer frame 37 is slightly shorter than the entire length of the coil part 30 and has a gap between the flange 11. By being configured in this manner, the pre-curing liquid material flows from the entire circumference of the upper and lower ends of the coil portion 30 into the portion that becomes the fixed layer 38, and the superconducting element wire 31, the heater wire 32, and the partition walls 33, 34 The liquid material is easily impregnated in the gap portion of the porous layer 36.

The spacer 13 is disposed so as to be in contact with both end surfaces of the superconducting wire 31 and the heater wire 32 wound around the bobbin main body 20. As shown in FIG. 4A, the spacer 13 is provided with a plurality of injection grooves 13G cut toward the center.
Along the injection groove 13G, the pre-curing liquid is injected into a portion that becomes the fixed layer 38. That is, since the injection groove 13G is provided in the contact surface of the flanges 11 and 12 that sandwich the coil portion 30 from above and below, the liquid material before curing in the gap between the superconducting element wire 31, the heater wire 32, and the porous layer 36. Will be promoted. The impregnation time can be adjusted by appropriately adjusting the number of the injection grooves 13G, the cross-sectional shape, and the like.

  As described above, the permanent current switch 10 having the structure described with reference to FIGS. 1 to 4 reduces the internal pressure loss, and can increase the filling property even when the impregnation pressure is low. Become. Further, the liquid is cured in a state where the filling property is high, whereby the superconducting element wire 31, the heater wire 32, the partition walls 33 and 34, the heat insulating film 35, and the porous layer 36 are integrated to have a stronger structure. Thus, the permanent current switch 10 in which quenching is unlikely to occur is obtained.

Next, with reference to FIG. 5, an embodiment of a manufacturing apparatus for a permanent current switch according to the present invention will be described.
The current switch manufacturing apparatus 90 includes a deaeration chamber 40, an impregnation chamber 50, a transport pipe 60, a pneumatic circuit 70, and a capacitance measuring instrument 80.
The current switch manufacturing apparatus 90 configured as described above is to manufacture a permanent current switch by impregnating the pre-impregnation switch 10 (see FIG. 1 as appropriate) with a thermosetting resin.

  The deaeration chamber 40 includes a stirrer 41, an observation window 42, a vacuum container 43, a resin reservoir container 44, and a temperature controller 45. The deaeration chamber 40 configured in this manner is located in the upper part of the impregnation chamber 50 to be described later, and the pre-curing liquid material forming the fixed layer 38 (see FIG. 2 as appropriate) is depressurized to remove the gas dissolved therein. I care. In the following, the “liquid body before curing” is a liquid resin in which two liquids of a main agent and a curing agent are mixed, and is a thermosetting resin that cures when heated.

The resin reservoir 44 is a container for holding a liquid resin in which two liquids of a main agent and a curing agent are mixed, and a thermometer T1 for measuring the temperature of the liquid resin is provided.
The stirrer 41 immerses and stirs rotating blades in a liquid resin held in a resin reservoir 44 to promote degassing of gas dissolved in the liquid resin.
The observation window 42 is for monitoring the deaeration status of the liquid resin held in the resin reservoir 44.
The vacuum container 43 is a container in which the resin reservoir container 44 is placed to keep the atmosphere in a vacuum, and is connected to a pneumatic circuit 70 described later.
The temperature controller 45 adjusts the liquid resin held in the resin reservoir 44 to a temperature at which degassing is optimally performed. This temperature adjustment is controlled based on the measured value of the thermometer T1 described above.

  The impregnation chamber 50 includes a pressure vessel 51, a resin receptacle 52, an impregnation vessel 53, and a heater 54. The impregnation chamber 50 configured as described above is located below the deaeration chamber 40, and is provided with the switch 10 before impregnation to reduce the pressure, impregnate the liquid resin, and then cure.

  The impregnation container 53 is a container in which the pre-impregnation switch 10 is disposed in advance and liquid resin transported from the deaeration chamber 40 through the transport pipe 60 is injected and submerged. The impregnation container 53 is provided with thermometers T2 to T4 for measuring the temperature of each part.

  The resin receptacle 52 is attached to the inner wall of the impregnation container 53 and is used to guide the liquid resin dripped from the tip of the transport pipe 60 to the bottom or the liquid level via the inner wall.

  The heater 54 is provided so as to be in contact with a part of the impregnation container 53 (in the drawing, is in contact with the bottom surface), and heats the liquid resin injected into the impregnation container 53 together with the permanent current switch 10 to cure them. It is. The heating by the heater 54 is controlled based on the measured values of the thermometers T2 to T4.

The pressure vessel 51 can hold the internal space in a state where the internal space is depressurized and pressurized from the atmospheric pressure, and the impregnation vessel 53 is placed in the internal space. The pressure vessel 51 is connected to a pneumatic circuit 70 which will be described later so as to communicate with the internal space, and a liquid level meter L for measuring the level of the liquid resin injected into the impregnation vessel 53.
Furthermore, the pressure vessel 51 is provided with an outlet for the lead wire from the superconducting element wire 31 connected to the capacitance measuring instrument 80 described later, and an outlet for the lead wire 24 whose one end is brazed to the bobbin body 20. It has been.

Here, the pressure vessel 51 is preferably capable of withstanding a vacuum force of 6 Pa or less and a pressing force of 0.93 MPa or more. It is assumed that the volume of the pressure vessel 51 is equal to or less than the volume V (m ³ ) derived by the following equation (1) regulated by the small pressure vessel of the “Boiler and Pressure Vessel Safety Regulations”.

Volume V (m ³ ) = 0.2 / Operating pressure (kg / cm ² G) (1)

  The transport pipe 60 communicates the deaeration chamber 40 and the impregnation chamber 50 and transports a liquid resin (liquid material). The transport pipe 60 is configured so that the degassed liquid resin can be directly injected from the deaeration chamber 40 into the impregnation chamber 50 in a reduced pressure state without touching the atmosphere.

  The pneumatic circuit 70 includes a pressure reducing valve 71, a pressure increasing valve 72, a first pipe 73, and a second pipe 74. The pneumatic circuit 70 configured as described above is for reducing the internal space of the deaeration chamber 40 or reducing / increasing the internal space of the impregnation chamber 50.

  One end of the first pipe 73 communicates with the vacuum vessel 43, the other end is connected to the pressure reducing valve 71, and a first opening / closing valve 73B and a pressure gauge P1 are provided along the way. The first pipe 73 configured as described above is for depressurizing the internal space of the deaeration chamber 40, and the pressure value is constantly measured by the pressure gauge P1, and the pressure value is appropriately measured by the first on-off valve 73B. Is to be adjusted.

  The second pipe 74 has one end communicating with the pressure vessel 51, the other end connected to the pressure reducing valve 71 and the pressure increasing valve 72, and a second opening / closing valve 74 </ b> B and a pressure gauge P <b> 2 provided on the way. The second pipe 74 configured as described above is for depressurizing / releasing to the atmosphere / pressurizing the internal space of the impregnation chamber 50. The pressure value is constantly measured by the pressure gauge P2, and the second on-off valve 74B, The pressure reducing valve 71 and the pressure increasing valve 72 are operated appropriately to adjust the pressure values.

  When the liquid resin is transported from the deaeration chamber 40 to the impregnation chamber 50, the pneumatic circuit 70 is adjusted so that the degree of vacuum in both internal spaces is the same. This is because the movement from the top to the bottom of the liquid resin proceeds smoothly only by the action of gravity, and so that the dissolved gas does not precipitate from the liquid resin injected into the impregnation container 53.

  The electrostatic capacity measuring device 80 measures the electrostatic capacity by connecting the lead wire 23 conducting to the bobbin main body 20 and the lead wire from the superconducting element wire 31 (see FIG. 2 as appropriate). The capacitance measuring device 80 configured in this way grasps the impregnation state by measuring the capacitance value that changes in accordance with the degree of impregnation of the liquid resin into the permanent current switch 10. (Refer to FIG. 7, capacitance C as appropriate).

As described above, the following effects are derived by configuring the manufacturing apparatus 90. That is, the deaeration chamber 40 and the impregnation chamber 50 are integrated through the transport pipe 60. Furthermore, the pneumatic circuit 70 can keep the internal space of the deaeration chamber 40 and the impregnation chamber 50 in a reduced pressure state of the same value. Thereby, it becomes possible to inject | pour liquid resin only by the effect | action of gravity, and it becomes possible to perform injection | pouring, without making liquid resin touch air.
Therefore, the air is prevented from being dissolved into the liquid resin, and when the permanent current switch 10 is impregnated with the liquid resin, the dissolved gas does not precipitate, so that the mixing of voids into the permanent current switch is suppressed. .

However, it is impossible to completely remove all the dissolved gas of the liquid resin, and if the liquid resin injected into the impregnation chamber 50 is left for a long time under reduced pressure, the generation of dissolved gas is inevitable. Here, the permanent current switch 10 has a structure in which the liquid resin is easily impregnated, and the advantage that the impregnation reaches a saturated state in a short time can be obtained. Furthermore, the capacitance meter 80 can measure the impregnation state of the liquid resin in real time.
As a result, it is possible to recognize the time point at which the impregnation speed of the liquid resin decreases, and if the pressure is increased at this time, the impregnation can be completed in a short time.

  Next, with reference to FIG. 5 and FIG. 6, an explanation of the operation of the manufacturing apparatus of the permanent current switch according to the present embodiment will be described, and this will be used as an explanation of the embodiment of the manufacturing method of the permanent current switch according to the present invention. To do.

The process A will be described separately for the process A in the deaeration chamber 40 and the process B in the impregnation chamber 50.
First, in the process A in the deaeration chamber 40, the resin reservoir 44 in which the main agent constituting the liquid resin and the curing agent are mixed is carried into the vacuum container 43 (step S11, hereinafter referred to as “S11”). After carrying in, the 1st on-off valve 73B of the 1st piping 73 and the pressure-reduction valve 71 are opened, and the vacuum vessel 43 is pressure-reduced to 6 Pa or less (S12). At the same time, the temperature controller 45 is operated to adjust the temperature of the liquid resin (S13), and the stirrer 41 is operated to start stirring of the liquid resin (S14). These steps (S12) to (S14) are in no particular order, but thereby the liquid resin is degassed and the dissolved gas is sufficiently discharged. Optimum conditions (temperature, degree of vacuum) for that are set appropriately.
The deaeration state of the liquid resin is monitored from the observation window 42, and when it is confirmed that no generation of voids is observed, the deaeration ends (S15).

  Next, in the process B in the impregnation chamber 50, the pre-impregnation switch 10 is set in the impregnation vessel 53 and carried into the pressure vessel 51 (S21). Next, the lead wire 23 and the superconducting strand 31 from the bobbin main body 20 are connected to the capacitance measuring device 80 (S22). Then, the second on-off valve 74B and the pressure reducing valve 71 of the second pipe 74 are opened to start pressure reduction (S23). In this state, the heater 54 is operated to heat up to the maximum temperature during curing, and the pre-impregnation switch 10 is vacuum-heated and dried (S24). The above is a preparation before impregnating the switch 10 with resin before impregnation.

  Next, the temperature of the impregnation vessel 53 including the pre-impregnation switch 10 is lowered to the resin impregnation temperature, that is, the temperature at which the liquid resin is set in the deaeration chamber 40, and the pressure of the pressure vessel 51 that fluctuates therewith is also released. The temperature and pressure are adjusted to be the same as the air chamber 40 (S25, S26: No). When the temperature and pressure conditions in the deaeration chamber 40 and the impregnation chamber 50 match (S26: Yes), the transport pipe 60 is used to inject the degassed liquid resin from the deaeration chamber 40 into the impregnation chamber 50. Is opened to start transportation (S27). At the same time, the measurement of capacitance by the capacitance measuring instrument 80 is started (S28).

Hereinafter, the description will be continued with reference to FIG.
The liquid resin to be injected travels along the inner wall via the resin receptacle 52 of the impregnation container 53 and drops and the liquid level rises. The liquid level is measured by the liquid level gauge L. Then, the liquid resin is injected until it is confirmed that the pre-impregnation switch 10 is submerged (S29, refer to the liquid level L in FIG. 7). In addition, it is preferable that the injection | pouring speed | velocity | rate of liquid resin is as fast as possible, and it is made to reach | attain the prescribed liquid level where the switch 10 before impregnation submerged in a short time. This is to avoid the risk that the dissolved gas of the liquid resin is deposited under reduced pressure. Then, after confirming that the pre-impregnation switch 10 is submerged, the pressure vessel 51 is immediately opened to atmospheric pressure (S30, see impregnation pressure P2 in FIG. 7).

  In this state, a pressure difference of about 1 atm is generated between the pressure in the impregnation region inside the pre-impregnation switch and the resin pressure, and the liquid resin flows into this impregnation region and the impregnation proceeds (FIG. 7). (See the rise of the capacitance C after S30). In addition, in the pre-impregnation switch having a structure in which the pressure loss in the impregnation region is small, the resin impregnation is completed quickly even with the pressure difference of 1 atm (that is, the rise of the capacitance C in FIG. 7 after S30). (The slope is large, and a flat region such as S32 and later can be reached quickly.)

Further, in order to complete the resin impregnation quickly, the pressure increase valve 72 of the pneumatic circuit 70 is opened to start pressurization in the pressure vessel 51 of the impregnation chamber 50 (see S31, impregnation pressure P2 in FIG. 7). Then, the impregnation of the liquid resin into the impregnation region inside the pre-impregnation switch is further accelerated (inclination after S31 of the capacitance C in FIG. 7 is increased).
Here, the subroutine of S32 will be described. Even when the pressurization is started (S31), when the slope of the capacitance C in FIG. 7 is small (that is, when the impregnation speed is a predetermined value or less (S42: No)), the applied pressure is further increased. (S42), the impregnation rate is made faster than a predetermined value (S42: Yes). Then, as shown after S43 of capacitance C in FIG. 7, when the change is stopped (that is, the impregnation speed is 0) (S43), the completion of the impregnation of the liquid resin is confirmed (return, S32). As a result, the time during which the liquid resin in the impregnation region inside the pre-impregnation switch is exposed to a reduced pressure state can be shortened, and precipitation of dissolved gas can be prevented. Note that if the resin impregnation is completed sufficiently quickly without performing such pressurization, the step S31 may be omitted and the jump may be directly made from S30 to S32 as indicated by a broken line.

  Thus, when the completion of impregnation of the liquid resin is confirmed, the heater 54 is operated to raise the temperature of the liquid resin and set it to the curing temperature (S33). Then, after the inside of the impregnation chamber 50 is opened to atmospheric pressure and the temperature is returned to room temperature (S34), the impregnation container 53 is carried out of the impregnation chamber 50, the surrounding excess cured resin is removed, and the permanent current switch 10 is taken out. (S35) A series of operations ends (END).

  By the way, when the permanent current switch 10 having the same structure is mass-produced, the measurement by the capacitance measuring instrument 80 is applied only to the permanent current switch 10 that is initially produced (S22, S28). Determine the time required. Then, the measurement of the capacitance is not performed for the second and subsequent permanent current switches 10 (S22 and S28 are excluded), and the resin impregnation can be performed according to the impregnation time established in the first production. .

  In other words, before mass production of permanent current switches, an impregnation test is performed using a prototype with the impregnation pressure as a parameter to find the optimum conditions for resin impregnation, and a manufacturing process suitable for mass production is formulated. In such a production process for mass production, capacitance measurement is unnecessary. Therefore, when many devices are installed, the capacitance measuring device 80 may be installed in only one device, and it is not necessary to install in other devices.

FIG. 8 shows the result of deriving the relationship between the resin impregnation pressure and the impregnation time for finding the optimum conditions for such resin impregnation. The resin impregnation time shown here is the result when a resin having a viscosity of 23 mPa · s is used. From this point, impregnation with resin impregnation pressure of 10MPa is about 26 (s), impregnation with atmospheric pressure of 0.1MPa is about 220 (s), and the maximum pressure of general air compressor is 0.93MPa, about 70 (s) It turns out that it impregnates.
Usually, the resin impregnation / curing step is a unit of time, and it can be seen that the impregnation time is a short time in units of minutes and seconds.

  From the above results, it can be seen that the permanent current switch according to the present invention has the structure as shown in the embodiment, so that high impregnation pressure is not required and resin impregnation is possible even at atmospheric pressure. . However, in consideration of the structure of the permanent current switch (the number of turns of the coil, the number of layers, etc.) and the case where the flow resistance is increased by changing the liquid resin, the manufacturing apparatus 90 according to this embodiment also has a mechanism for applying pressure. It was set as the structure provided. In the present invention, the applied pressure is controlled from the atmospheric pressure to 0.93 MPa, the upper limit of which is 0.93 MPa, which is the maximum pressure of a general air compressor, as the control range of the impregnation pressure.

It is a whole composition / partial sectional view showing an embodiment of a permanent current switch concerning the present invention. It is detail drawing of the A cross section view part of the permanent current switch of FIG. It is a figure which shows the partition wall installed in the interlayer of the superconducting strand employ | adopted as the permanent current switch which concerns on this embodiment, and the pore provided in it. It is (a) top view (b) side view of the spacer provided between the flange and coil part which are employ | adopted as the permanent current switch which concerns on this embodiment. It is a whole lineblock diagram showing an embodiment of a manufacture device of a permanent current switch concerning the present invention. It is a flowchart which shows embodiment of the manufacturing method of the permanent current switch which concerns on this invention. It is a measurement result showing the resin impregnation process in the manufacturing apparatus of the permanent current switch which concerns on this embodiment. It is a graph which shows the relationship between the resin impregnation pressure and the impregnation time in the manufacturing apparatus of the permanent current switch which concerns on this embodiment.

Explanation of symbols

10 Permanent current switch (switch before impregnation)
DESCRIPTION OF SYMBOLS 11 Flange 12 Nut 13 Spacer 13G Injection groove 20 Bobbin main body 23 Electrical insulation material 30 Coil part 31 (31L, 31R) Superconducting strand 32 Heater wire 33, 34 Partition wall 33h Pore 36 Porous layer 37 Outer frame 37G Injection gap 38 Fixed Layer 40 Deaeration Chamber 50 Impregnation Chamber 60 Transport Pipe 70 Pneumatic Circuit 71 Pressure Reducing Valve 72 Pressure Boosting Valve 80 Capacitance Measuring Instrument 90 Permanent Current Switch Manufacturing Equipment

Claims (10)

In the permanent current switch for controlling the permanent current flowing in the superconductor,
A superconducting wire connected to the superconductor and wound around a bobbin body;
A heater wire that switches the superconducting state / normal state by heating the superconducting wire;
A partition wall provided between layers of the superconducting element wire or the heater wire wound around the bobbin body, and having a plurality of pores;
A permanent current switch comprising: a fixed layer that impregnates and fixes the pores and a gap between the superconducting element wire and the heater wire. The permanent current switch according to claim 1,
The superconducting element wire or the heater wire is wound around the bobbin main body so as to be squarely arranged in a cross-sectional view,
The permanent current switch according to claim 1, wherein the pore is provided in the partition wall so as to be positioned substantially at the center of the unit region of the square arrangement. The permanent current switch according to claim 1 or 2,
A permanent current further comprising an injection groove arranged to be in contact with both end faces of the superconducting wire wound around the bobbin main body and the heater wire and into which the liquid material before hardening of the fixed layer is injected. switch. The permanent current switch according to any one of claims 1 to 3,
A permanent current switch, characterized in that injection gaps for injecting a liquid before curing of the fixed layer are provided on both end faces of an outer frame provided on the outer periphery of the portion to be the fixed layer. In the manufacturing apparatus which manufactures the permanent current switch of any one of Claims 1-4,
A degassing chamber for degassing the liquid before curing the fixed layer by depressurizing;
An impregnation chamber for arranging and depressurizing the permanent current switch in a state before the fixed layer is impregnated;
An apparatus for manufacturing a permanent current switch, comprising: a transport pipe that communicates the deaeration chamber and the impregnation chamber and transports the liquid material. In the manufacturing apparatus of the permanent current switch according to claim 5,
An apparatus for manufacturing a permanent current switch, comprising: a capacitance measuring device that connects a lead wire conducted to the bobbin main body and a lead wire from the superconducting element wire to measure a capacitance. In the manufacturing apparatus of the permanent current switch according to claim 5 or 6,
An apparatus for manufacturing a permanent current switch, wherein when the liquid material is transported by the transport pipe, the deaeration chamber and the impregnation chamber are set to the same pressure of 6 Pa or less. In the manufacturing apparatus of the permanent current switch according to any one of claims 5 to 7,
The impregnation chamber can be further increased in pressure, and the pressure is set to 0.93 MPa or less. In the manufacturing apparatus of the permanent current switch according to claim 8,
An apparatus for manufacturing a permanent current switch, wherein the pressure vessel constituting the impregnation chamber is set to a working pressure of 0.93 MPa or less and a volume V (m ³ ) or less derived by the following equation.
Volume V (m ³ ) = 0.2 / Operating pressure (kg / cm ² G) In the manufacturing method of the permanent current switch according to any one of claims 1 to 4,
Disposing and depressurizing a permanent current switch in a state before the fixed layer is impregnated;
Transporting the liquid material before curing of the fixed layer to the permanent current switch in a decompressed state;
Measuring the capacitance between the bobbin body and the superconducting element wire while increasing the pressure applied to the permanent current switch.

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