JPH09148102A - Liquid-cooled resistor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid-cooled resistor capable of being manufactured easily as well as of avoiding the corrosion and partial discharging. SOLUTION: A ribbed 46 inner cylinder 4A is coaxially contained inside an outer cylinder 1. This inner cylinder 4A is molded out of Teflon material. On the other hand, a cover alloy made connecting tube 2 is junctioned with the outer cylinder 1 by brazing process. Next, a cover 3 is junctioned with the upper part of this connecting tube 2 by TIG welding process so as to form a fitting part on a lower end of a leading pipe 5A penetrating into the cover 3 for forcibly inserting this fitting part into a forcibly inserting hole on the upper end of the inner cylinder 4A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-cooled resistor used in, for example, a water-cooled power semiconductor converter.

[0002]

2. Description of the Related Art An example of a conventional liquid-cooled resistor is shown in a vertical sectional view of FIG. In FIG. 3, a circular recess 1a in a plan view (not shown) is formed at the bottom of the outer cylinder 1 made of a porcelain (alumina oxide) into a cylindrical body having a U-shaped vertical cross section.

A resistance wire 7 is spirally wound around the outer cylinder 1, and terminal plates 6 fixed to the upper and lower parts of the outer cylinder 1 are connected to both ends of the resistance wire 7. Resistance wire 7
Is fixed to the outer cylinder 1 by a wire stopper material 8 of silicone rubber applied to the outer peripheral surface of the outer cylinder 1, increases the heat transfer rate with the outer cylinder 1, and is blocked from the outside air for a long period of time. Oxidation due to energization is prevented.

Inside the outer cylinder 1, an inner cylinder 4B made of a stainless steel (SUS304L) material having a spiral fold 4b1 formed on the outer circumference of the cylinder is inserted coaxially with the outer cylinder 1, and the inner cylinder 4B The lower end is loosely fitted in a circular recess 1a formed in the bottom of the outer cylinder 1, and a through hole 4a is formed on the left side in FIG. 3 at the upper part of this loose fitting portion.

A metallized layer 9 is formed on the upper end surface of the outer cylinder 1, and a disc-shaped lid 3 made of stainless steel is placed on the upper end surface of the metallized layer 9 and brazed with silver solder. It is joined.

Further, an outlet pipe 5B is provided on the lid 3 so as to penetrate to the right side in FIG. 3, and the left side of the outlet pipe 5B is the center of the outlet pipe 5B and the left side thereof is the same product as the outlet pipe 5B. 5A is pierced.

In the liquid-cooled resistor thus constructed, the resistance wire 7 is wound after the lid 3 is joined, and the wire stopper 8 having a curing temperature of 120 ° C. is finally applied. Also,
A joint (not shown) is connected to the upper end of the outlet pipe 5A penetrating the lid 3, and cooling water of pure water is supplied from a pipe (not shown) connected to the joint to the inner cylinder 4B as indicated by an arrow A. Is supplied inside.

Then, as shown by arrow B, this cooling water flows out of the lower end of the inner cylinder 4B through the through hole 4a at the lower end of the inner cylinder 4B, and is formed in a spiral shape on the outer periphery of the inner cylinder 4B. As shown by an arrow C, the spiral flow path formed between the pleats 4b1 and the outer cylinder 1 flows upward.

Further, this cooling water flows from the right side of the upper end of the inner cylinder 4B in FIG. 3 to an external pipe (not shown) as shown by an arrow D. The outflowing cooling water is cooled by a not-shown cooler, and then supplied again by a not-shown pump.

With the inflow and outflow of this cooling water, the inner cylinder 4
The outer cylinder 1 is cooled by the cooling water spirally flowing between the pleats 4b1 of B and the outer cylinder 1, and the resistance wire 7 and the wire stopper material wound around the outer cylinder 1 are cooled by the cooled outer cylinder 1. 8 is cooled to a predetermined temperature.

Incidentally, the liquid-cooled resistor is used by being incorporated in a snubber circuit or the like of a power conversion device composed of a semiconductor element such as a thyristor. Therefore, the resistance line 7
Is applied with a high voltage of, for example, AC5kVRMS. When brazing the lid 3 to the outer cylinder 1,
The temperature is around 800 ° C., and in this case, the upper portion of the inner cylinder 4B is also heated.

[0012]

However, in the liquid-cooled resistor constructed as described above, it takes a long time to manufacture and attach the pleats 4b1 of the inner cylinder 4B. That is, in order to manufacture the pleats 4b1, it is necessary to wind strip-shaped stainless steel around the rod of the jig, or punch it into a ring and then make a notch and connect the cut portion by welding or the like.

Of these methods, the former method not only requires hot work to lower the working environment, but also requires the strip material to be thick. Then, the width of the cross section of the flow path of the cooling water decreases, and the pressure loss increases. Moreover, the folds 4b1
Since the roundness is not obtained, a gap may be formed between the inner circumference of the outer cylinder 1.

In the latter method, it takes a long time to perform the connecting work by welding the cut portion. In either case, increasing the flow rate of the cooling water may corrode the surface of the stainless steel material. Then, the pressure loss of the flow path of the cooling water increases.

Further, a partial discharge is generated in a gap partially formed between the outer circumference of the pleats 4b1 and the inner circumference of the outer cylinder 1 (note: in one experiment by the inventors, the resistance wire 7 and the inner cylinder 1). 4B
The starting voltage of the partial discharge between and is AC 2.5-3.0 kVR
It was MS. ), The oxygen contained in the cooling water is ionized by this partial discharge, and the resistance value is lowered.

Furthermore, since the inner cylinder 4B and the resistance wire 7 are opposed to each other via the outer cylinder 1, the high frequency current applied to the resistance wire 7 flows through the cooling water due to the stray capacitance interposed therebetween, and There is a possibility that the electric current may flow to another electric device via the pipe connected to the outlet pipes 5A and 5B and cause the other electric device to malfunction. Therefore, an object of the present invention is to obtain a liquid-cooled resistor which is easy to manufacture and which can prevent corrosion and partial discharge.

[0017]

According to a first aspect of the present invention, there is provided a liquid-cooled resistor having a spiral pleated inside an outer cylinder in which a resistor is wound around an outer periphery and a high voltage is applied to the resistor. In the liquid-cooled resistor in which the inner cylinder formed on the outer periphery is inserted, the cooling liquid flowing from the injection pipe of the lid on the end surface of the outer cylinder into the inner cylinder is allowed to flow through the folds and discharged from the discharge pipe of the lid. It is characterized in that a spacing tube is interposed between the end surface of the cylinder and the lid.

The liquid-cooled resistor according to the second aspect of the invention is characterized in that the inner cylinder is an insulating resin molded product.

The liquid-cooled resistor according to the third aspect of the invention is characterized in that the material of the insulating resin molded product is Teflon.

The liquid cooling resistor according to the fourth aspect of the present invention is characterized in that the interval pipe is made of Kovar alloy.

Furthermore, the liquid-cooled resistor according to a fifth aspect of the present invention is characterized in that the tip of the injection pipe is press-fitted into a press-fitting hole formed in the inner cylinder.

In the liquid-cooled resistor by such means, the inner cylinder is formed at the same time including the folds, and the dielectric constant is similar to that of the outer cylinder, and is formed between the inner circumference of the outer cylinder and the folds. The electric field in the gap is relaxed.

[0023]

1 is a longitudinal sectional view showing an embodiment of a liquid cooling resistor according to the present invention and is a view corresponding to FIG. 3 shown in the prior art. Therefore, the same parts as in FIG.
The same reference numerals are given.

In FIG. 1, the inner cylinder 4A is manufactured by molding a Teflon material including the folds 4b, and a short cylindrical connecting pipe 2 is inserted between the upper end of the outer cylinder 1 and the lid 3. And are joined as described later.

Of these, the connecting pipe 2 is made of Kovar alloy (29Ni-16Co-Fe). In addition, lid 3
The outer cylinder 1 is brazed to the outer cylinder 1 by TIG welding.

Further, the inner cylinder 4A and the outlet pipe 5A are connected by press fitting as shown in FIG. That is, the press-fitting hole 4C shown in FIG. 2 is formed at the upper end of the inner cylinder 4A,
A fitting portion 5a having a substantially truncated cone shape is formed at the lower end of the outlet pipe 5A.

In the liquid cooling resistor thus constructed, the connecting pipe 2 is brazed through the metallized layer 9 formed on the upper end of the outer cylinder 1, and then the inner cylinder 4A is placed inside the outer cylinder 1. To insert.

Next, the lid 3 in which the outlet pipes 5A and 5B are provided in advance is placed on the upper end of the connecting pipe 2, and the outer circumference is joined to the connecting pipe 2 by TIG welding 10.

In the liquid-cooled resistor thus constructed, the inner cylinder 4A can be easily manufactured including the pleats 4a. Moreover, since the inner tube 4A has the lower end of the outlet pipe 5A press-fitted to the upper end, it does not move even if it is turned upside down in the process of transportation from the factory to the installation site.

The heat of about 800 ° C. when the lid 3 is welded to the upper surface of the connecting pipe 2 reaches the upper end of the inner cylinder 4A, and the temperature thereof is lowered by the outlet pipe 5A. It can also prevent deformation and softening.

Furthermore, the Teflon material of the inner tube 4A does not permanently corrode regardless of the flow rate of the cooling water and can be made thin, so that the pressure loss of the cooling water flow path is reduced. Therefore, the cooling effect of the resistance wire 7 and the wire stopper 8 can be improved, and the weight of the liquid cooling resistor can be reduced.

Further, since the pleats 4b are also made of Teflon material, there is no stray capacitance between them and the resistance wire 7,
Even if a slight gap is partially formed between the outer circumference of the fold 4b and the inner circumference of the outer cylinder 1, since the values of the dielectric constants are close to each other, there is no possibility of partial discharge, The risk of ionization of oxygen contained in the cooling water can be eliminated.

In the above embodiments, the case where the material of the inner cylinder 4A is Teflon has been described, but other resins such as polyether imito resin, polysulfone resin or Teflon resin can be used as long as heat resistance and water resistance are satisfied. KF polymer resin may be used.

Further, in the above embodiment, the case where the resistor provided on the outer periphery of the outer cylinder 1 is a resistance wire has been described, but the same applies to the case of a carbon-coated resistor, for example. You can

[0035]

As described above, according to the present invention, the inner cylinder formed on the outer periphery of the spiral fold is inserted into the outer cylinder in which the resistor is wound around the outer periphery and a high voltage is applied to the resistor. In a liquid-cooled resistor in which the cooling liquid that has flowed from the injection pipe of the lid on the end face of the outer cylinder into the inner pipe flows through the folds and is discharged from the discharge pipe of the lid, a space pipe is placed between the end face of the outer cylinder and the lid. In addition, the inner cylinder is made of an insulating resin molded product so that the inner cylinder can be molded at the same time including the folds, and the induction ratio can be approximated to that of the outer cylinder. Since the electric field in the gap between the two is relaxed, it is possible to obtain a liquid-cooled resistor which is easy to manufacture and which can prevent corrosion and partial discharge.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a liquid cooling resistor of the present invention.

FIG. 2 is an enlarged partial longitudinal sectional view showing a main part of the liquid cooling resistor of the present invention.

FIG. 3 is a vertical sectional view showing an example of a conventional liquid cooling resistor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Outer cylinder, 2 ... Connection pipe, 3 ... Lid, 4A ... Inner cylinder, 4b ... Crimp, 5A, 5B ... Exit pipe, 6 ... Terminal, 7 ... Resistance wire, 8 ...
Wire stopper, 9 ... Metallized layer, 10 ... TIG welding.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takafumi Fujimoto 1st Toshiba-cho, Fuchu-shi, Tokyo Toshiba Corporation Fuchu factory

Claims (5)

[Claims] 1. An inner cylinder formed on the outer circumference of a spiral fold is inserted into an outer cylinder in which a resistor is wound around an outer circumference and a high voltage is applied to the resistor, and an end surface of the outer cylinder is inserted. In a liquid-cooled resistor that allows the cooling liquid that has flowed from the injection pipe of the lid to the inner cylinder to flow through the folds and to be discharged from the discharge pipe of the lid, a space pipe is provided between the end surface of the outer cylinder and the lid. A liquid-cooled resistor characterized by being interposed. 2. The liquid cooling resistor according to claim 1, wherein the inner cylinder is an insulating resin molded product. 3. The liquid-cooled resistor according to claim 2, wherein the material of the insulating resin molded product is Teflon. 4. The liquid-cooled resistor according to claim 1, wherein the space tube is made of Kovar alloy. 5. The liquid cooling resistor according to claim 1, wherein the tip of the injection pipe is press-fitted into a press-fitting hole formed in the inner cylinder.