JPS5844172B2 - Heat exchanger manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a heat exchanger used in an electric instantaneous water heater, and more specifically, to a method for manufacturing a heat exchanger used in an electric instantaneous water heater, and more specifically, it relates to a method for manufacturing a heat exchanger used in an electric instantaneous water heater, and more specifically, a method for manufacturing a heat exchanger used in an electric instantaneous water heater. and a residual heat absorption tank communicating with the water pipe is inserted into the cylindrical space formed by the rod-shaped heating element and the water pipe, which are arranged in close contact with each other alternately to form a cylindrical space. The present invention relates to a method of manufacturing a heat exchanger configured as follows.

Structure of the conventional example and its problems In the past, there was no structure as described above, and the present invention is disclosed in Japanese Patent Application No. 52-73594 (Japanese Unexamined Patent Publication No. 547643) filed by the same applicant on June 20, 1972. This is a further improvement of the heat exchanger for the electric instantaneous water heater shown in ).

FIG. 1 shows the structure of the heat exchanger of the conventional electric instantaneous water heater shown in the above-mentioned earlier application.As shown in FIG. A cylindrical space 5 is formed in the inner circumferential part by spirally bending the cylindrical space 5 in close contact with the remaining heat absorbing tank 6. It is constructed by bringing the outer peripheral wall of the residual heat absorption tank 6 into contact with the inner peripheral wall of the heating element 1 and the water pipe 2, that is, by bringing the rod-shaped heating element 1, the water pipe 2, and the residual heat absorption tank 6 into contact with each other. There is.

The inflow lower part of the residual heat absorption tank 6 is located at the lower part, and the outlet 8 is located at the upper part, and the valve 3 is provided in the pipe 9 connected to the inlet lower part.

The rod-shaped heating element 1 uses a sheathed heater, and the water pipe 2 uses copper having high thermal conductivity.

A terminal 4 at the tip of the rod-shaped heating element 1 is electrically connected in series with a microswitch (not shown).

This microswitch (not shown) is operated by a receiving plate (not shown) that is in contact with a diaphragm (not shown) built into the valve 3.

In Fig. 1 above, when valve 3 is opened and water is allowed to flow from the direction of arrow A, the diaphragm built into valve 3 moves due to water pressure, and the receiving plate in contact with this diaphragm activates the micro switch. The rod-shaped heating element 1 is electrically short-circuited and energized.

On the other hand, the water proceeds from the vibrator 9 to the inflow lower part to the residual heat absorption tank 6 to the outlet 8 to the water pipe 2.

Due to the heat generated by the rod-shaped heating element 10, the water that comes into contact with the rod-shaped heating element 1 and passes through the water pipe 2 is exchanged with hot water by thermal conduction, and flows out as shown by arrow B.

This water is used for hand washing or showering.

In this type of heat exchanger, the rod-shaped heating element 1 has a power density of 13 to 100, because it is necessary to instantaneously exchange heat from running water to hot water.
I am using one with a high output of 20W/crA.

On the other hand, when hot water supply is stopped, the valve 3 is closed to stop the flow of water from the normal usage state, and at the same time the rod-shaped heating element 1 is closed.
However, since the rod-shaped heating element 1 has a high power density, it has considerable residual heat, and when the valve 3 is closed, the water in the water pipe 2 is further heated by the residual heat. Then, an after-boiling phenomenon occurs.

This after-boiling phenomenon means that even if the flow of water is stopped and the power supply to the rod-shaped heating element 1 is stopped, the water in the water pipe 2 reaches a boiling state due to the residual heat of the rod-shaped heating element 10, and the water in the water pipe 2 reaches a boiling state.
This is a phenomenon in which the internal pressure inside the tank rises and hot water gushes out to the hot water supply side.

This phenomenon occurs when consumers use the appliance for washing their hands or taking a shower, and they are unconsciously exposed to hot water, which can lead to accidents such as burns.

In order to absorb the residual heat of the heater that leads to such an after-boiling phenomenon, a residual heat absorption tank 6 is provided in contact with the rod-shaped heating element 1 and the water pipe 2, thereby completely eliminating the after-boiling phenomenon.

Further, the contact between the residual heat absorption tank 6, the rod-shaped heating element 1, and the water pipe 2 makes the heat exchange rate highly stable.

As described above, the performance of the heat exchanger for the electric instantaneous water heater depends on the quality of the contact between the rod-shaped heating element 1, the water pipe 2, and the residual heat absorption tank 6.

Conventionally, a method for manufacturing a heat exchanger having the above-mentioned performance has been to separately prepare a rod-shaped heating element 1 which is bent into a spiral shape.
By interlocking and screwing the and water pipe 2 together,
Both J and 2 are brought into contact with each other, and then a residual heat absorption tank 6 having an outer diameter equal to the inner diameter of the spirally curved rod-shaped heating element 1 or the water pipe 2, or slightly equal to the inner diameter of the water pipe 2, is attached to the above-mentioned both 12. The residual heat absorption tank 6 is inserted into the cylindrical space 5 composed of Connect them to each other, weld or braze the joints, and then attach the rod-shaped heating element 1,
A heat exchanger was manufactured by fixing the water pipe 2 and the residual heat absorption tank 6 by brazing.

However, in this manufacturing method, by meshing and screwing together the spirally curved rod-shaped heating element 1 and the water pipe 2, it is difficult to make contact over the entire circumference even if the two 12 are brought into contact. As a result, there is a problem in that many local non-contact parts occur due to springback or the like.

Furthermore, the diameter when curved spirally (represented by φ in FIG. 1) varies widely due to springback, and as a result, a large gap is created between the outer diameter φ' of the residual heat absorption tank 6. Because of this, it is not possible to bring the rod-shaped heating element 1, the water pipe 2, and the residual heat absorption tank into complete contact.Therefore, in order to make this contact good, it is necessary to have the highest processing precision. requested and as a result,
This required expensive processing costs and was irrational in terms of mass production.

Therefore, in the past, a method was used in which the non-contact parts due to the variations in processing were forcibly brought into contact by welding or brazing.

However, when brazing is processed, it is easy to ensure contact between the rod-shaped heating element 1 and the water pipe 2, but it also makes it easier to ensure contact between the rod-shaped heating element 1, the residual heat absorption tank 6, and the water pipe 2. Therefore, when used as a heat exchanger after processing, it may result in a product with low heat exchange efficiency, or a product that repeatedly suffers from the after-boiling phenomenon, which is a fatal factor for heat exchangers. It happens.

Therefore, in the past, it was necessary to maintain the stability of heat exchanger characteristics only by using expensive processing methods that improve processing accuracy and brazing, which had the problem of extremely poor mass production. .

Purpose of the Invention In view of the above conventional problems, the present invention provides a residual heat absorption tank,
The purpose of the present invention is to provide a method for manufacturing a heat exchanger that can ensure contact with a rod-shaped heating element and a water pipe without requiring high processing precision, and can exhibit excellent effects in terms of mass production. It is something.

Structure of the Invention In order to achieve the above object, the manufacturing method of the present invention includes a step of bending a rod-shaped heating element and a water pipe in a spiral shape while closely contacting each other alternately so as to form a cylindrical space on the inner periphery. and inserting a residual heat absorption tank having both ends open into the cylindrical space formed by the rod-shaped heating element and the water pipe, and connecting in series one end opening of the residual heat absorption tank and one end opening of the water pipe. , temporarily seal the other end opening of the residual heat absorption tank, apply water pressure from the other end opening of the water pipe to inflate the residual heat absorption tank, and connect the outer peripheral wall of the residual heat absorption tank to the rod-shaped heating element in the cylindrical space and the water pipe. and a step of subsequently opening a temporary seal at the other end opening of the residual heat absorption tank. According to this manufacturing method, The residual heat absorption tank inserted into the cylindrical space is inflated by applying water pressure from the other end of the water pipe.
This ensures that the outer peripheral wall of the residual heat absorption tank is in close contact with the rod-shaped heating element and the inner peripheral wall of the water pipe, and as a result,
The contact between the three parts can be achieved reliably without requiring precision processing of the rod-shaped heating element and the water pipe, and it is possible to achieve reliable contact between the rod-shaped heating element and the water pipe. Since no processing is required, the number of processing steps and processing costs can be reduced, and as a result, it is possible to obtain a product that is extremely suitable for mass production.

Description of examples Hereinafter, one embodiment of the present invention will be described based on the drawings.

In the manufacturing method according to an embodiment of the present invention, first, the rod-shaped heating element 1 and the water pipe 2 are alternately brought into close contact with each other and then bent spirally to form a cylindrical space 5 in the inner peripheral portion.

Next, a residual heat absorption tank 6 which is open at both ends, that is, has an inlet lower and an outlet 8, is inserted into the cylindrical space 5.

After that, the opening at one end of the residual heat absorption tank 6, that is, the outlet 8, and the opening at one end of the water pipe 2 are connected in series by brazing or the like, and the opening at the other end of the residual heat absorption tank 6, that is, the inflow lower is connected as shown in FIG. Temporary sealing 10 is performed as shown, and water pressure is applied from the other end opening of the water pipe 2 connected in series to the residual heat absorption tank 6 as shown in FIG. 2 to inflate the residual heat absorption tank 6 by the water pressure. The outer peripheral wall of the residual heat absorption tank 6 is expanded and deformed as shown in FIG.
The rod-shaped heating element 1 in the cylindrical space 5 is brought into close contact with the inner circumferential wall of the water pipe 2.

Thereafter, the opening at the other end of the residual heat absorption tank 6, that is, the temporary seal 10 of the inflow lower is removed to open the inflow lower.

Note that when applying water pressure with the inflow lower of the residual heat absorption tank 6 temporarily sealed 10, the water pipe 2 and the residual heat absorption tank 6 are filled with water, as shown in FIG. It is something that exists.

As described above, according to the manufacturing method in one embodiment of the present invention,
Due to the expansion and deformation, the residual heat absorption tank 6 has an outer circumferential wall deformed into a wave shape, and comes into close contact with the inner circumferential walls of the rod-shaped heating element 1 and the water pipe 2.

Therefore, with this processing method, even if the machining accuracy of the spirally curved rod-shaped heating element 1 and the water pipe 2 is low, it can be sufficiently put into practical use, and the inner diameter of the curved rod-shaped heating element 1 and the water pipe 2 can be There is no problem even if there is a sufficient gap in the outer diameter of the residual heat absorption tank 6, and the non-contact area between the three parts caused by these dimensional differences can be removed by applying water pressure according to an embodiment of the present invention. , it is extremely easy to bring all parts into a close contact state, and as a result, it is possible to provide a heat exchanger that is easy to process, inexpensive, has stable characteristics, and is highly suitable for mass production. .

Further, when the spirally curved rod-shaped heating element 1 and the water pipe 2 are simply screwed together and assembled as in the past, a gap of 0-0.31rLrIl is created, but in one embodiment of the present invention, By applying water pressure of 140 kg/cr;t, it was possible to eliminate gaps all around the circumference.

Furthermore, if the difference between the inner diameter of the curved rod-shaped heating element 1, the water pipe 2, and the outer diameter of the residual heat absorption tank 6 is within 1 m7'It, and a water pressure of 140 kg/cm is applied, as shown in Fig. 3. It deformed into a wavy shape and adhered closely.

Note that the heat exchanger manufactured according to one embodiment of the present invention is as follows:
After its manufacture, the pipe 9 is connected to the inflow lower part of the residual heat absorption tank 6.
are connected to each other, and only the contact portions on the outer periphery of the rod-shaped heating element 1 and the water pipe 2 are sealed from the outside to prevent the occurrence of non-contact portions after manufacture.

Effects of the Invention As described above, according to the manufacturing method of the present invention, a residual heat absorption tank inserted into a cylindrical space constituted by a rod-shaped heating element and a water pipe is heated by applying water pressure from the opening at the other end of the water pipe. Since it is inflated, this ensures that the outer peripheral wall of the residual heat absorption tank is in close contact with the rod-shaped heating element and the inner peripheral wall of the water pipe, and as a result, the contact between the three is limited to the rod-shaped heating element and the It is possible to obtain a reliable product without requiring precision processing of water pipes, and brazing, which is an extremely difficult task to ensure contact between three parts in the past, does not require processing, so the processing process can be improved. As well as reduction in processing costs, it is possible to obtain a product that is extremely suitable for mass production.Moreover, the contact between the rod-shaped heating element, the water pipe, and the residual heat absorption tank is reduced compared to the conventional method. Since the point contact becomes a surface contact, the heat exchange efficiency as a heat exchanger becomes stable, and as a result, it is possible to eliminate the after-boiling phenomenon that can be said to be fatal to a heat exchanger.

[Brief explanation of the drawing]

Fig. 1 is a partial sectional view of a heat exchanger for an electric instantaneous water heater showing a conventional example, Fig. 2 is a schematic diagram showing a manufacturing method of a heat exchanger for an electric instantaneous water heater according to an embodiment of the present invention, and Fig. 3 is a diagram after the production. FIG. 3 is a cross-sectional view showing the state of the heat exchanger. 1... Rod-shaped heating element, 2... Water pipe, 3
...Barun, 5-19. ...Cylindrical space, 6.
... Residual heat absorption tank, γ ... Inlet, 8
...Outlet, 9...Pipe.

Claims (1)

[Scope of Claims] 1. A step in which a rod-shaped heating element and a water pipe are alternately brought into close contact with each other so as to form a cylindrical space on the inner periphery, and then curved in a spiral shape; A process of inserting a residual heat absorption tank with both ends open into the cylindrical space formed by sealing and applying water pressure from the other end opening of the water pipe to inflate the residual heat absorption tank to bring the outer peripheral wall of the residual heat absorption tank into close contact with the rod-shaped heating element in the cylindrical space and the inner peripheral wall of the water pipe; A method for manufacturing a heat exchanger comprising: opening a temporary seal at the other end opening of the residual heat absorption tank. 2. The heat exchanger according to claim 1, further comprising the step of brazing the close contact portion between the rod-shaped heating element and the water pipe from the outside after the step of bringing the rod-shaped heating element into close contact with the inner circumferential wall of the water pipe. Manufacturing method.