JPH0552424A - Electric water heater - Google Patents

Abstract

PURPOSE:To improve the corrosion resistance of the weld between a tank flange and an edge of the mounting hole for the heater without increasing the cost. CONSTITUTION:In a packing 21, on its inner circumferential side and at the part where the packing 21 is contiguous to a tank flange 13, a relief 22 is formed toward a direction in which the packing 21 separates from a weld 18 with the tank flange 13. Thus, the packing 21 is in contact with the tank flange 13 at positions located with some space from the weld 18. At the weld 18 in this state, hot water has a good fluidity and concentration of chlorine ions in the hot water does not occur so that corrosion in the interstices at the weld 18 can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater that heats water in a tank into hot water by a heater arranged in the tank to supply hot water.

[0002]

2. Description of the Related Art A conventional electric water heater is disclosed in, for example, Japanese Unexamined Patent Publication No.
As described in Japanese Patent No. 169963, a tank is provided with a heater mounting port, an annular tank flange is welded and fixed to an edge of the heater mounting port, and the tank flange is provided with a heater arranged in the tank. The heater flange has a quadrangular cross section and is attached via an annular packing.

By the way, since oxide scale is generated in the welded portion between the tank flange and the edge portion of the heater mounting opening (including the portion affected by heat), corrosion is likely to occur. Further, since the packing is in contact in the vicinity of the welding of the tank flange, warm water stagnates in the corner portion between the tank flange and the packing, cl of water as a negative effect on corrosion - ^(chlorine ions) are concentrated, is crevice corrosion Likely to happen. Therefore, crevice corrosion is likely to occur from the oxide scale as a starting point, and there is a problem in corrosion resistance particularly when used in an area where water quality is poor and chlorine concentration is high.

In view of this, in the above publication, after the tank flange is welded to the edge of the heater mounting port, the welded portion is subjected to passivation treatment by electrolytic polishing to ensure corrosion resistance.

[0005]

As described above, conventionally, in order to secure the corrosion resistance of the welded portion between the tank flange and the edge of the heater mounting port, the passivation treatment is performed by electrolytic polishing. However, since the manufacturing process is increased, the cost is increased.

The present invention has been made in view of the above circumstances, and it is possible to improve the corrosion resistance of the welded portion between the tank flange and the edge of the heater mounting port without increasing the cost. The purpose is to provide a water heater.

[0007]

According to the present invention, a heater mounting port is provided in a tank, an annular tank flange is welded and fixed to an edge of the heater mounting port, and a heater disposed in the tank is fixed to the tank flange. In an electric water heater in which a heater flange provided is attached via an annular packing, the packing has a larger diameter toward the outer peripheral direction away from the welded part of the tank flange on the side of the inner peripheral part in contact with the tank flange. The escape portion is formed.

[0008]

In the present invention, since the packing is in contact with the portion of the tank flange away from the welded portion due to the relief portion of the packing, hot water in the tank easily flows to the welded portion, and chlorine is concentrated at the welded portion. Therefore, the occurrence of crevice corrosion starting from the oxide scale of the weld is prevented.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of one embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 shows a tank 1 of an electric water heater. The tank 1 has the same steel plate as the body 2 on the upper and lower parts of a body 2 formed in a cylindrical shape from a ferritic stainless steel plate having high corrosion resistance. The mirror bodies 3 formed by press molding are welded and fixed. Joints 4 connected to the hot water supply pipe and the water supply pipe are welded and fixed to the tops of the upper and lower mirror bodies 3, respectively.

FIG. 1 shows a heater mounting portion provided on a lower portion of one side of a body 2 of a tank 1. A circular heater mounting opening 11 is formed in the body 2, and an edge portion 12 of the heater mounting opening 11 is formed.
Are formed so as to project outward.

A tank flange 13 is welded and fixed to an edge portion 12 of the heater mounting port 11. This tank flange 13
A fixing portion 14 fitted to the outer periphery of the edge portion 12, a seal step portion 16 having a substantially L-shaped cross section having a sealing surface 15 protruding from the fixing portion 14 in the outer diameter direction, and an outer diameter direction from the seal step portion 16. It is formed in an annular shape from a mounting portion 17 that protrudes inward. And the edge
The tip of 12 and the fixed portion 14 are welded together to form a welded portion 18.

An annular packing 21 is attached to the seal step portion 16 of the tank flange 13. This packing 21
Is made of rubber, and an escape portion 22 is formed on the inner peripheral side of the tank flange 13 in contact with the tank flange 13 and has a diameter increasing toward the outer peripheral direction away from the welded portion 18 of the tank flange 13. Also,
Packing 21 bonded to the sealing surface 15 of the tank flange 13
On the side surface of the, a substantially triangular projection 23 that forms the escape portion 22 is formed to project, and a projection 24 that is joined to the corner of the seal step portion 16 is formed to project between both projections 23, 24. A groove 25 is formed in the groove.

The width of the packing 21 is larger than the depth of the seal step portion 16 and protrudes from the mounting portion 17 in the state before mounting the heater flange 31, which will be described later, and is pressed by the mounting of the heater flange 31. The tank flange 13 and the heater flange 31 are dimensioned so that a predetermined pressure contact force can be obtained.

A heater flange 31 for closing the heater mounting port 11 is attached to the tank flange 13. The heater flange 31 is formed in a disk shape, and a plate portion 32 protruding toward the heater mounting port 11 is formed in the central portion, and a peripheral portion of the plate portion 32 is joined to the mounting portion 17 of the tank flange 13 to be illustrated. Not to be fixed with bolts and nuts
Are formed. The heater flange 31 is provided with a heater 34 arranged inside the tank 1.

Thus, in the thus constructed electric water heater, the packing 21 seals between the tank flange 13 and the heater flange 31.

By the way, in the welded portion 18 of the tank flange 13, oxide scale is generated during welding.
The packing 21 is in contact with the sealing surface 15 near the 18 and hot water is stagnated at the corner between the tank flange 13 and the packing 21, chlorine ion which has a bad influence on corrosion is concentrated, and crevice corrosion starts from the oxide scale. Cheap. Further, it is known that this crevice corrosion is unlikely to occur in a portion where hot water flows and is likely to occur in a portion where hot water is stagnant.

However, the packing 21 is formed with an escape portion 22 which escapes in a direction away from the welded portion 18,
Since the protrusion 23 of 21 is in contact with the seal surface 15 away from the welded portion 18, hot water easily flows to the welded portion 18, and chlorine ions are not concentrated in the welded portion 18, so that the welded portion 18 It is possible to prevent the occurrence of crevice corrosion starting from the oxide scale.

As described above, by only setting the shape of the packing 21, the welded portion 18 can be used without increasing the cost, especially when used in an area where the water quality is poor and the chlorine concentration is high.
The corrosion resistance of can be improved.

Further, since the hot water easily flows to the welded portion 18, oxygen contained in the hot water has a function of contacting the welded portion 18 to form an immovable body film, and the occurrence of corrosion can be suppressed. ..

Even if the sealing performance of the protrusion 23 of the packing 21 is deteriorated, the protrusion 24 can prevent water leakage.

Next, FIGS. 3 and 4 show another embodiment of the present invention. In this embodiment, the packing 21 and the escape portion 22 are provided.
Is formed with a protrusion 23 that is joined to the seal step portion 16, and a flat plate portion 41 that is sandwiched between the mounting portion 17 of the tank flange 13 and the mounting portion 33 of the heater flange 31 is formed. The flat plate portion 41 is formed with a through hole 43 through which a bolt 42 for fixing the tank flange 13 and the heater flange 31 is inserted.

The bolt 42 is inserted through the through hole 31a of the heater flange 31 and the through hole 43 of the packing 21, and is screwed into the burring portion 44 provided on the tank flange 13 to fix the heater flange 31 in the packing 21. Through the tank flange 13
Tighten and fix to.

Also in the case of this embodiment, by the escape portion 22,
It is possible to obtain the same effect as that of the above-mentioned embodiment.

The cross-sectional shape of the packing 21 is not limited to the above-mentioned embodiments, and the welding portion 18 of the tank flange 13 is formed on the inner peripheral portion of the packing 21 on the side in contact with the tank flange 13 such as a circle or a rhombus. What is necessary is that the relief portion 22 having a large diameter is formed in the outer peripheral direction away from.

[0026]

According to the present invention, on the side of the inner peripheral portion of the packing which is in contact with the tank flange, there is formed the relief portion which becomes larger in diameter toward the outer peripheral direction away from the welded portion of the tank flange. The flange is in contact with the part away from the welded part, the hot water in the tank easily flows to the welded part, chlorine ions in the hot water are not concentrated in the welded part, and the gap from the oxide scale of the welded part is the starting point. Corrosion can be prevented, and therefore, only by setting the shape of packing, without increasing the cost, especially when used in areas with poor water quality and high chlorine concentration,
It is possible to improve the corrosion resistance of the welded portion.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an embodiment of an electric water heater of the present invention.

FIG. 2 is a side view of the tank.

FIG. 3 is a partial cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a front view of the packing.

[Explanation of symbols]

 1 Tank 11 Heater Mounting Port 12 Edge 13 Tank Flange 18 Weld 21 Packing 22 Relief 31 Heater Flange 34 Heater

Claims (1)

[Claims] 1. A heater mounting port is provided in a tank, and an annular tank flange is welded and fixed to an edge of the heater mounting port,
In this electric water heater in which a heater flange provided with a heater arranged in the tank is attached to the tank flange via an annular packing, the packing is formed by welding the tank flange to a side of the inner peripheral portion in contact with the tank flange. An electric water heater characterized in that a relief portion having a large diameter is formed in the outer peripheral direction away from the portion.