JPH10191596A - Water-cooled electric equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-cooled electric equipment capable of preventing effectively the drop of dielectric strength even if high voltage is impressed between metal joints and even if the length of an insulating pipe is shortened. SOLUTION: At least a circulating pump, a heat exchanger and a storage tank for cooling water are piped to an object to be cooled through an insulating pipe, and in a water-cooled electric equipment having a potential difference between metal joints 9 connected to both ends of the insulating pipe 8, a stepped front end section 14 as an adhesion prevention device for preventing the deposit of stains to the insulating pipe 8 is provided in the metal joint 9 on lower electric potential side. By the constitution, dielectric strength of the insulating pipe is not decreased, and short-circuit can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-cooled electric device such as a water-cooled generator and a fuel cell.

[0002]

2. Description of the Related Art Generally, a water-cooled electric device has a large number of electric devices as objects to be cooled. In this cooling type electric device, a metal joint installed in a cooling water pipe is connected via an insulating pipe, and cooling water supplied through the cooling water pipe flows into the electric device to cool the electric device. .

FIG. 5 shows the overall structure of a conventional water-cooled electric device. In FIG. 5, reference numeral 1 denotes a circulating pump for cooling water W, 2 denotes a heat exchanger, and 3 denotes an ion-exchange resin tower for maintaining the quality of the cooling water W at high purity (low conductivity). Reference numeral 4 denotes a cooling water pipe formed in an annular shape so as to include the circulation pump 1 and the heat exchanger 2, and reference numeral 5 denotes a cooling water pipe 4 formed in an annular shape so as to include the ion-exchange resin tower 3, and an entrance / exit point of the circulation pump 1. This is a water treatment pipe for cooling water W connected by P and Q. 6
Is a flow control valve provided on the upstream side of the ion-exchange resin tower 3 of the water treatment pipe 5; 7 is an electric device provided on the downstream side of the heat exchanger 2 of the cooling water pipe 4; An insulating pipe connected between the metal fitting 9 at the end of the water pipe 4;
Reference numeral 10 denotes a storage tank for the cooling water W which communicates with the communication point Q of the cooling water pipe 4 via the pipe 11. Further, a voltage is applied to the electric device 7, and a potential difference is generated between the metal joints 9 connected to both ends of the insulating tube 8.

Next, the operation of the conventional water-cooled electric equipment will be described. When the circulation pump 1 is operated, a part of the cooling water W is sent to the cooling water pipe 4 and supplied to the heat exchanger 2, and the rest of the cooling water W is sent to the cooling water pipe 5 and the ion exchange resin Feed to tower 3. In this case, the ratio of the flow rate on the cooling water pipe 4 side to the flow rate on the cooling water pipe 5 side is determined by the opening degree of the flow control valve 6. After passing through the heat exchanger 2, the cooled cooling water W is supplied into the electric device 7, cools the electric device 7, and then returns to the circulation pump 1.
Returned to the side.

FIG. 6 shows details around a metal joint 9 connected to the insulating tube 8. The metal joint 9 is attached to both ends of the cooling water pipe 4, and the tip 9 a of the metal joint 9 is
It is plugged inside. Then, the end 8a of the insulating tube 8 bent into a flange shape and the metal joint 9 are attached to the cap nut 12.
And the cooling water flows inside the insulating tube 8.

[0006] By the way, metal parts such as copper and iron are used in a water circulation system of a water-cooled electric device, and when these parts are corroded, metal ions (cations) are generated in the cooling water as shown in the following equation. Generate.

M → M ^{n +} + ne where M represents a metal, n represents a valence, and e represents an electron.

Since a potential difference is generated between the metal joints 9 connected to both ends of the insulating tube 8, when metal ions reach the vicinity of the metal joint 9 on the low potential side, they adhere to the metal joint 9.

M ^{n +} + ne → M... M ^{n +} + nH ₂ O → M (OH) _n + nH ⁺ ... M (OH) _n is a metal hydroxide .

The above formulas, the metals and metal hydroxides in the above formulas are corrosion products, and other metal oxides are also conceivable.
When these corrosion products grow along the insulating tube 8, the insulating tube 8 is contaminated, and the withstand voltage of the insulating tube 8 may be reduced to cause a short circuit.

In order to prevent such a short circuit, it is only necessary to prevent corrosion of a metal component which is a cause of the generation of corrosion products.
As a method of preventing corrosion of such a metal part, adoption or coating of a corrosion-resistant material for a metal part having a potential difference is considered, while for a metal part having no potential difference,
Adoption or coating of a corrosion-resistant material, prevention of oxygen from dissolving in cooling water, or removal of dissolved oxygen can be considered.

That is, metal parts include parts having a potential difference such as a metal joint and parts having no potential difference such as a heat exchanger.

In a part having a potential difference, for example, a metal joint, a metal joint having a high potential is corroded. As a countermeasure against this corrosion, it is conceivable to employ a corrosion-resistant material such as stainless steel for the component, or to coat the component with a corrosion-resistant material such as TiN.

In general, components having no potential difference are corroded when dissolved oxygen is present in the cooling water. As a countermeasure, adoption or coating of a corrosion resistant material such as stainless steel can be considered. The adoption of a corrosion-resistant material or a coating for preventing corrosion of a metal part may be difficult to apply depending on the type of the metal part. For example, copper is generally used in a heat exchanger, which is one of the metal parts, in consideration of cooling performance. However, if another material is used for corrosion protection, the cost increases. Therefore, depending on the type of the metal part, the material change may be limited, and it is difficult to completely suppress corrosion.

On the other hand, as another method of preventing corrosion of metal parts having no potential difference, it is conceivable to prevent oxygen from dissolving into cooling water, which is a cause of corrosion, or to remove dissolved oxygen, for the following reasons. In addition, dissolved oxygen cannot be completely removed.

That is, since a potential difference is generated between the metal joints connected to both ends of the insulating tube, if the potential difference is large, oxygen or hydrogen is converted into water by the electrolysis of water as shown in the following equation. Occurs on the surface.

On the surface of the metal joint on the high potential side, 2H ₂ O → O ₂ + 4H ⁺ + 4e... On the surface of the metal joint on the low potential side, 2H ₂ O + 2e → H ₂ + 2OH ^−. ... Therefore, if a potential difference is generated between the metal joints at both ends of the insulating tube, dissolved oxygen will be present in the water circulation system, and the metal parts will corrode. For this reason, it is difficult to completely suppress the corrosion of a metal part having no potential difference.

Incidentally, in order to remove corrosion products,
For example, cleaning with a sponge ball is performed (see Japanese Patent Application Laid-Open No. 2-272300). However, when this method is applied to a water-cooled generator, the workability deteriorates because the insulated pipe having dirt must be removed.
Therefore, it is necessary to prevent dirt from adhering to the insulating tube.

From the above, in order to prevent a decrease in the withstand voltage of the insulating tube, it is necessary to prevent corrosion products from adhering to the insulating tube on the premise that metal parts are corroded. .

[0020]

As described above, when there is a potential difference between the metal joints located at both ends of the insulating tube, the metal ions generated by corrosion of the metal parts are reduced to the low potential side metal joint. When it grows along the insulating tube by adhering to the surface, there is a case where the withstand voltage is reduced and a short circuit occurs. In recent years, with the miniaturization and high performance of water-cooled electric equipment, the length of the insulating tube has been reduced, and therefore, measures against short-circuiting are indispensable.

The present invention has been made in order to solve the above-described problems, and is effective even when a high voltage is applied between metal joints or when the length of an insulating tube is shortened. An object of the present invention is to provide a water-cooled electric device that can prevent a decrease in withstand voltage.

[0022]

According to a water-cooled electric apparatus of the present invention, at least a circulation pump, a heat exchanger and a storage tank for cooling water are piped to an object to be cooled through an insulating pipe, and both ends of the insulating pipe are provided. A water-cooled electric device in which a potential difference occurs between connected members, wherein the low-potential side connection member is provided with adhesion preventing means for preventing adhesion of dirt to the insulating tube. Features.

Preferably, the connection member is a metal joint.

Preferably, the adhesion preventing means comprises a stepped tip portion of the metal joint which forms an annular groove in an outer peripheral surface of a tip portion of the fitting portion of the metal joint inserted into the insulating tube. It is preferable that a water passage for preventing cooling water from staying between the insulating pipe and the stepped tip of the metal joint is provided at the stepped tip.

Preferably, the adhesion preventing means has an electric field concentrated shape.

[0026] Preferably, the adhesion preventing means is provided at a tapered tip portion of the metal joint, which forms a taper cut surface inside a tip outer peripheral surface of a fitting portion of the metal joint inserted into the insulating tube. preferable.

[0027] It is preferable that a flow channel for preventing cooling water from staying between the insulating tube and the tapered tip of the metal joint is provided at the tapered tip.

[0028] It is preferable that the adhesion preventing means is formed of a non-conductive member formed on a distal end surface of a fitting portion of the metal joint inserted into the insulating tube.

[0029]

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

[First Embodiment] FIG. 1 is a cross-sectional view of a main part showing a metal joint in a water-cooled electric apparatus according to a first embodiment of the present invention. The basic structure of the water-cooled electric device is common to the water-cooled electric device shown in FIG. 5, and at least the circulation pump, the heat exchanger and the storage tank of the cooling water are electric objects to be cooled via the insulating pipe. Piped to
A potential difference is generated between the metal joints 9 as connection members connected to both ends of the insulating tube 8.

Further, the metal joint 9 on the low potential side is provided with an adhesion preventing means for preventing adhesion of dirt to the insulating tube.

As the adhesion preventing means, an annular groove 13 is formed on the outer peripheral surface of the distal end of the fitting portion of the metal joint 9 inserted into the insulating tube 8, and the stepped distal end portion 14 of the metal joint 9 is formed.
Has been adopted. The stepped tip 14 is separated from the insulating tube 8 by the annular groove 13. The length X1 between the insulating tube 8 and the stepped tip 14 of the metal joint 9 which is a distance in a direction perpendicular to the longitudinal direction of the insulating tube 8 and the metal joint 9 which is a distance in the longitudinal direction of the insulating tube 8 Stepped tip 1
4, the length Y1 is not particularly limited, but usually X1 =
0.5 mm or more and Y1 = 2 mm or more.

According to the first embodiment, the stepped tip of the metal joint on the low potential side tends to grow in the cooling water toward the metal joint on the high potential side. As a result, the attached matter is peeled off, thereby preventing the attached matter from growing. In addition, the adhered substance peeled off from the stepped tip of the metal joint circulates in the cooling water. If the cooling water is maintained at a high purity (low conductivity), the cooling water is redissolved and becomes a metal ion and is captured by the ion exchange resin, so that the attached matter can be removed. Alternatively, in order to remove the deposits from the cooling water, it is preferable to install a filter in a circulation path of the cooling water, for example, before the cooling water flows into the ion-exchange resin tower (any part of the water pipe 5).

[Second Embodiment] FIG. 2 is a sectional view showing a main part of a metal joint in a water-cooled electric apparatus according to a second embodiment of the present invention. This metal joint has an electric field concentrated shape with an acute angle at the tip in order to prevent adhesion of dirt to the insulating tube. As the electric field concentration shape, the tip of the metal joint only needs to be an acute angle. For example, as shown in FIG.
Forming a tapered cut surface 15a inside on the outer peripheral surface at the distal end of the fitting portion of the metal joint 9 inserted into the insulating tube 8;
The tapered tip 15 of the metal joint can be used.
The length X2 between the insulating tube 8 and the tapered tip 15 of the metal joint 9 which is the distance in the direction perpendicular to the longitudinal direction of the insulating tube 8
The length Y2 of the tapered tip 15 of the metal joint 9, which is the distance in the longitudinal direction of the insulating tube 8, is not particularly limited, but is usually X2 = 0.5 mm or more and Y2 = 2 mm or more.

Third Embodiment FIG. 3 is a cross-sectional view of a main part showing a metal joint in a water-cooled electric device according to a third embodiment of the present invention. In order to further suppress the adhesion of dirt as compared with the first and second embodiments, as shown in FIG. 3, the metal joint 9 has its tip 16 separated from the insulating tube 8 and has a thickness A flowing water passage 17 penetrating in the vertical direction is provided. Thereby, the insulating tube 8 and the distal end portion 16 of the metal joint 9 are formed.
Since it is possible to prevent the cooling water 18 from staying during this period, even under conditions where a higher voltage is applied, metal ions do not concentrate, and the adhesion of dirt to the metal joint 9 can be more effectively prevented. FIG.
In the metal joint of (1), a flowing water channel is provided at the tip of the metal joint of FIG. 1. However, a flowing water channel can be similarly provided at the tip of the metal joint of FIG.

[Fourth Embodiment] FIG. 4 is a cross-sectional view of a main part showing a metal joint in a water-cooled electric apparatus according to a fourth embodiment of the present invention. The metal joint 9 is obtained by coating a non-conductive member 20 on the distal end surface of a fitting portion 19 of the metal joint. As the non-conductive member 20, for example, glass or ceramics such as Al ₂ O ₃ can be used. The coating thickness is not particularly limited, but is usually 1 μm or more.

As a result, the corrosion product adheres to the inside 21 of the distal end portion of the metal joint, but is stripped off by the flow of the cooling water, so that the growth of the deposit is inhibited.

Example 1 In order to investigate the prevention of the adhesion of dirt to the insulating tube, a cooling water circulating device simulating a water-cooled electric device shown in FIG. 5 was manufactured, and a stepped tip as shown in FIG. An experiment was conducted to compare the formed metal joint with the conventional metal joint shown in FIG. The experimental conditions were as follows: electric field strength between metal joints = 1 kV / cm, conductivity of cooling water = 1.0 μS
/ Cm or less, the flow rate of the cooling water = 1 m / s, and a copper tube was installed in order to simulate the water contact part of the heat exchanger.

As a result of the experiment, in the metal joint on the low potential side shown in FIG.
It did not grow along the insulating tube. On the other hand, in the conventional metal joint on the low potential side, an adhering matter was required at the tip thereof, and it grew along the insulating tube.

The length of the stepped tip of the metal joint was X1 = 0.5 mm and Y1 = 2 mm. Therefore, the longer the length X1 is, the longer the length X1 is from the insulating tube. On the other hand, the length Y must be increased as the electric field intensity increases, but under the above experimental conditions, the growth of the deposit can be prevented if at least Y1 = 2 mm. As a result of analyzing the attached matter, it was found that the substance was copper oxide, which was a corrosion product of a copper tube. After the copper pipe installed in the cooling water circulation device corrodes and produces copper ions, it is oxidized by dissolved oxygen in the cooling water until it reaches the metal joint, or after the copper ions precipitate as metallic copper on the metal joint, It is considered that it was oxidized by dissolved oxygen in the cooling water. Copper oxide has conductivity, and when it grows along the insulating tube and reaches the metal joint on the high potential side,
The phenomenon of short-circuit was confirmed in another experiment. Therefore, in order to prevent a short circuit, it is necessary to prevent the copper oxide from growing along the insulating tube, and the growth can be prevented by using the metal joint having the tip shown in FIG.

Example 2 In order to investigate the effect of preventing corrosion products from adhering to an insulating tube, the cooling water circulation device described in Example 1 was used to form a tapered tip as shown in FIG. An experiment was conducted on the metal joint and the conventional metal joint shown in FIG. 6 under the same conditions.

As a result of the experiment, the conventional metal joint (low potential side)
At the tip, a deposit was found, and it grew along the insulating tube. On the other hand, in the metal joint (low-potential side) shown in FIG. 2, it was recognized that the adhesion was concentrated because the tip portion was an electric field concentration portion, but it did not grow along the insulating tube. .

Incidentally, the metal joint shown in FIG. 2 used in the experiment has a tapered tip portion having a length of X2 = 0.5 mm and a length of Y2 = 0.5 mm.
2 = 2 mm. Therefore, the longer the length X2 is, the longer the length X2 is from the insulating tube. Further, the length Y1 must be increased as the electric field intensity increases. However, under the experimental conditions of the first embodiment, the growth of the deposit can be prevented if at least Y2 = 2 mm.

[0044]

As described above, according to the present invention, by providing an adhesion preventing means for preventing the adhesion of dirt to the insulating tube, the withstand voltage of the insulating tube is not reduced and a short circuit is prevented. can do. As a result, high reliability can be ensured even if a high voltage is applied to the metal joint pipe of the water-cooled electric device, and even if the insulating tube is shortened due to miniaturization and high performance of the water-cooled electric device.

When the adhesion preventing means is a stepped tip, since the stepped tip is separated from the insulating tube, dirt does not grow along the insulating tube. Therefore, the withstand voltage of the insulating tube is not reduced, and a short circuit can be prevented.

Further, when the adhesion preventing means is a tapered tip, the tapered tip is separated from the insulating tube and has an electric field concentration shape, so that dirt is more easily concentrated and adhered to the tapered tip. , Dirt does not grow along the insulation tube. Therefore, the withstand voltage of the insulating tube is not reduced, and a short circuit can be prevented.

Further, if a water channel is provided at the stepped or tapered tip portion, the dirt component is not concentrated at the tip portion of the metal joint, so that the adhesion of the dirt to the insulating pipe can be prevented. Therefore, the withstand voltage of the insulating tube is not reduced, and a short circuit can be prevented.

Further, when the adhesion preventing means is a non-conductive member, the growth of dirt along the insulating tube is suppressed. Therefore, the withstand voltage of the insulating tube is not reduced, and a short circuit can be prevented.

[Brief description of the drawings]

FIG. 1 is a fragmentary cross-sectional view showing a metal joint in a water-cooled electric device according to Embodiment 1 of the present invention.

FIG. 2 is a fragmentary cross-sectional view showing a metal joint in a water-cooled electric device according to Embodiment 2 of the present invention.

FIG. 3 is a cross-sectional view of a main part showing a metal joint in a water-cooled electric device according to a third embodiment of the present invention.

FIG. 4 is a fragmentary cross-sectional view showing a metal joint in a water-cooled electric device according to Embodiment 4 of the present invention.

FIG. 5 is a diagram showing an overall configuration of a conventional water-cooled electric device.

FIG. 6 is a view showing a conventional metal joint.

[Explanation of symbols]

1 pump, 2 heat exchanger, 3 ion exchange resin tower, 4
Cooling water piping, 5 water treatment piping, 6 flow control valve, 7
Electrical equipment, 8 insulation pipe, 8a insulation pipe end, 9 metal joint, 10 storage tank, 11 piping, 13 annular groove, 14 stepped tip, 15 tapered tip, 15a
Tapered cut surface, 16 Tip, 17 Flow channel, 18
Cooling water between the insulating tube and the metal joint tip, 19 fitting part,
20 Non-conductive member, 21 Inside the tip of metal joint, X
1. X2 Length between insulating tube and metal joint tip (perpendicular to longitudinal direction of insulating tube), Y1, Y2 Length of metal joint tip (longitudinal direction of insulating tube), W cooling water.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nobuyoshi Takahashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Electric Corporation (72) Inventor Kenichi Mori 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Rishi Electric Co., Ltd.

Claims (7)

[Claims] 1. A water cooling system wherein at least a circulation pump, a heat exchanger, and a storage tank for cooling water are piped to an object to be cooled via an insulating pipe, and a potential difference is generated between metal joints connected to both ends of the insulating pipe. A water-cooled electrical device, wherein the low-potential-side metal joint is provided with adhesion preventing means for preventing dirt from adhering to the insulating tube. 2. The metal joint according to claim 1, wherein the adhesion preventing means comprises a stepped tip portion of the metal joint, which forms an annular groove in a tip outer peripheral surface of a fitting portion of the metal joint inserted into the insulating tube.
The water-cooled electrical device as described. 3. The water-cooled electric device according to claim 2, wherein a water passage is provided at the stepped end to prevent stagnation of cooling water between the insulating tube and the stepped end of the metal joint. machine. 4. The water-cooled electric device according to claim 1, wherein said adhesion preventing means has an electric field concentration shape. 5. The tapered tip of the metal joint, wherein the adhesion preventing means forms a tapered cut surface inside an outer peripheral surface of a tip of a fitting part of the metal joint inserted into the insulating tube. 4. The water-cooled electric device according to 4. 6. The water-cooled electric device according to claim 5, wherein a flow passage for preventing cooling water from staying between the insulating tube and the tapered tip of the metal joint is provided at the tapered tip. 7. The water-cooled electric device according to claim 1, wherein said adhesion preventing means is formed of a non-conductive member formed on a distal end surface of a fitting portion of said metal joint inserted into said insulating tube.