JPS59183237A - Tap-operated electric water heater - Google Patents

Abstract

PURPOSE:To prevent the parts of the water heater other than the heater proper from being overheated at the time of abnormal heating by the heater by a method wherein a heat exchanger is electrically insulated even when the electric insulation property of the heater deteriorates, a leak electric current is controlled to a minimum by using a water supply pipe, a hot water supply pipe and a fixing device all of which are made of electrical insulating material. CONSTITUTION:The heat exchanger 4 is electrically insulated from the other constitutional parts of the water heater such as a chassis 8, the water supply pipe and the like by the fixing device comprising an insulated pipe 19, an insulated stationary plate 18, an insulated fixing washer 19 and a flat washer 20 all made of an electric insulating material and therefore, when the electric insulation of the sheath heater 1 deteriorates, electricity leaking from the sheath heater 1 flows through a human body via water within a heat insulating pipe 17 of the heat exchanger 4, the water supply pipe 2, the hot water supply pipe 3 and an external pipe when the human body touches upon a cock but the human body senses no electricity in using the heater. Further, as the insulating pipe 17 is compact and housed within the body of the water heater, the body itself has two step insulating functions and therefore, the temperature of a functional part such as a flow rate switch and that of the chassis are kept low even at the time of heating so that no trouble or erroneous operation of the water heater takes place and the temperature of the heater fitting wall is kept low to thereby improve safety.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an electric instantaneous water heater.

Configuration of conventional example and its problems For example, the conventional electric instantaneous water heater shown in FIGS. 1 and 2 is as follows:
The sheathed heater 1, water inlet pipe 2, and hot water outlet pipe 3 are watertightly brazed to the heat exchanger 4, and the flow rate operation switch 6 is connected to the water inlet pipe 2.
The heat exchanger 4 is connected watertightly to the middle of the bolt 1.
6, a nut 6, and a spring washer 7.

Moreover, since it is used in a humid place such as a bathroom, power is distributed via an earth leakage breaker 14 or the like. When the cock 12 is opened to allow water to flow, the flow rate switch 6 is activated and the sheathed heater 1 is energized, and the water that has flowed in through the water inlet 9 is heated and flows through the water outlet 1o.
It will be leaked. Considering the environment in which an electric instantaneous water heater is used, it can be used in a humid place such as a bathroom or shower room, and in a state where the human body is completely naked and wet, i.e., when the electrical resistance of the human body is extremely low, as shown in Figure 2. Touch the metal part of the cock 12 as shown. If the electrical insulation of the sheathed heater 1 deteriorates, a large current will flow through the heat exchanger 4, external piping 13, and cock 12 to the human body, creating a very dangerous situation. In order to prevent this, earthing work has been carried out, but even in this case, human body resistance Rm =: 1.5KQ (levitation tSR1 Assuming that the contact pressure is 22 ov) and the ground 16 has undergone type 3 grounding work, and that the grounding resistance Re is 0.1 and Ω, in the equivalent circuit of the current of the conventional product shown in Fig. 6, the sheathed heater 1 The current In flowing through the human body when the electrical insulation resistance R1 is changed from (1) to 0 is as shown by line a in the graph of FIG. J'jx,'+! ! When fg Ri is 20 in state j, Im = 162 mA, which is fatal to the human body.

In other words, the ground 16 alone cannot be said to be safe depending on the conditions. Therefore, in order to ensure further safety, conventionally,
In some cases, an earth leakage circuit breaker 14 was installed, but in this case, the insulation of the sheathed heater 1 deteriorated only slightly, which had little effect, and the 7444 double circuit breaker 14 operated.
There was a drawback that the electric instantaneous water heater body 11 could no longer be boiled, making it unusable. In addition, as shown in Fig. 4 in the hot water storage type 1F water heater, the conventional method was to electrically insulate the main body 21 of the hot water storage type electric water heater with an external insulating tube 22 approximately 1 m long. When used in electric instantaneous water heaters, the piping work was complicated, and there were disadvantages in that the external parts of the main body were not electrically insulated (3). 6 and the like are thermally connected to each other, the temperature of the flow rate switch 6 rises when the heater is abnormally heated, resulting in failure and malfunction.

OBJECTS OF THE INVENTION The present invention solves the drawbacks of the conventional heaters, and aims to enable safe and normal use by suppressing the current as much as possible even when the electrical insulation of the heater deteriorates. Furthermore, the purpose is to prevent other parts from heating when the heater overheats.

Structure of the Invention In order to achieve the above object, the present invention provides a heat exchanger with a water supply pipe, a hot water outlet pipe, and a fixing device made of electrically insulating material.
It provides electrical insulation.

DESCRIPTION OF EMBODIMENTS Hereinafter, one embodiment of the present invention will be explained based on the drawings.

In FIG. 3, the same reference numerals as in FIG. 1 are the same, and the method of heating the running water is no different from the conventional example, so a description thereof will be omitted. When the electrical insulation of the sheathed heater 1 is deteriorated, the electricity leaked from the sheathed heater 1 is sent to the cock 1.
When 2 is touched by a human body, the water inside the heat exchanger 4 insulating tube 17,
The water flows to the human body via the water supply pipe 2, outlet pipe 3, external pipe 13, and cock 12. .

Figure 7 t11, this 11.1i':'j1+l11 circuit, 1 human body resistance Rm = 1, 3 KΩ, earth grounding resistance Re = 0.1Ω, electrical resistance Rw of water inside the insulating tube 17 Current flowing through the human body when the electrical insulation resistance Ri of the sheathed heater 1 is changed from normal to O when corresponds to line b in the graph of FIG. In the worst condition Ri=O, In=1,6
mA, which is sufficiently safe for the human body. Also, see Figure 8.
Even if the electrical insulation of the heater 15 deteriorates to 6Ω, the human body will not feel any electricity and can still use this electric water heater (R
1 m = 1 mA when i = 6 KΩ). The insulating tube 15 is compact and is housed within the main body 11 as shown in FIG. 3, so the main body 11 itself has a two-stage insulation function, and the external piping 13 in FIG. There is no longer a need to turn it into a thing. There are also metal parts on the main body surface that are likely to be touched by the human body, such as bolts 16 for fixing the cover.
Tiered insulation. In addition, since the sheathed heater 1, heat exchanger 4, flow rate switch 6, chassis 8, etc. in the high-temperature section are not thermally connected, the temperature of the flow rate switch 6, etc. is low and there is no failure or malfunction even when heating V11 normally. The increase in humidity on the mounting wall, etc. via the chassis 8 has also been reduced. Note 18
is an insulation [1 fixed stand, 19 is an insulation fixing washer, and 20 is a flat washer.

Effects of the Invention As described above, according to the present invention, the following effects can be obtained.

(1) Since the heat exchanger is electrically insulated from other main body components such as the chassis, water supply pipes, hot water taps, etc. by insulating tubes and fixing devices made of electrically insulating materials, the sheathed heater insulation deteriorates. However, it can be used safely and normally, and does not require other safety devices such as earth leakage circuit breakers. Furthermore, even when the heater is abnormally heated, the temperature of functional parts such as the flow rate switch, the chassis, etc. is low, preventing failures and malfunctions, and the temperature of the mounting wall is also low, improving safety.

(2) Since the insulating tube is inside the main body, there is no need for external piping with electrically insulating material.

This has the effect of

[Brief explanation of the drawing]

Figures 1a and b are front sectional views and side sectional views of a conventional electric instantaneous water heater, Figure 2 is a perspective view of an example of the construction of the electric instantaneous water heater, and Figures 3a and b. 4 is a front sectional view and a side sectional view of an electric instantaneous water heater that is an embodiment of the present invention, and FIG.
Fig. 6 is a graph of the relationship between human body resistance and contact voltage, Fig. 6 is an equivalent circuit diagram of a conventional electric instantaneous generator and a human body, and Fig. 7 is a graph of the relationship between human body resistance and contact voltage. 1: Equivalent circuit diagram of the device and the human body. FIG. 8 is a graph showing changes in ionization through the human body as the heater resistance deteriorates in the equivalent circuits of FIGS. 6 and 7. 1 Sheathed heater, 2... Water inlet pipe, 3...
... Hot water pipe, 4 ... Heat exchanger, 6 ... Flow rate switch, 6 ... Nut, 7 ...... Washer, 8 ... Chassis, 9... Water entry L1.10
...... Water outlet, 11 ... Electric instantaneous water heater body, 12 ... Cock, 13 ... External self-conductor, 14 ... Earth leakage breaker, 16...
Earth, 16...Port, 17...Insulation tube, 18...Insulation fixing stand, 19...Insulation fixing washer, 20... Flat washer, 21...
...Hot water storage type electric water heater body, 22...External insulation tube. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 ((L)
(b) Figure 5

Claims (1)

[Claims] (1) A heat exchanger with a heater, a water supply pipe, a hot water outlet pipe, a fixing device for fixing the heat exchanger to the chassis, all or part of the water supply pipe and the hot water outlet pipe, An electric instantaneous water heater in which the heat exchanger is electrically isolated from other components by constructing the fixing device with an electrically insulating material. 2)) The electric instantaneous water heater according to claim 1, wherein the water supply pipe and the hot water outlet pipe are located inside the main body.