JPH0526510A - Electric hot water maker - Google Patents

Abstract

PURPOSE:To provide an electric hot water maker which prevents a damage to the heater by stopping the electric current to it when an abnormality is detected which is caused by operating the heater with no water in the device. CONSTITUTION:The temperature of the hot water detected by a temperature sensor 5 of a heat accumulating tank 1 and the time spent from supplying electric current to a heater 2 are stored in a memory 4c in the times that are beforehand set. The value stored in this memory 4c is substituted in the calculation formula of a calculator 4a that is beforehand set. By this calculator 4a the value that is calculated by this calculator 4a and the numerical value that is beforehand set are compared by an identification device 4b, and by the signal from this identification device the electric current supplied to the heater is stopped at the time of an abnormality that heating is made with no water in the device.

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 for heating hot water in a tank using a heating wire, which prevents damage to the equipment due to emptying which is an electric heating before water supply. Is.

[0002]

2. Description of the Related Art As shown in FIGS. 4 and 5, a conventional electric water heater of this type is provided with a heating device 2 (hereinafter collectively referred to as a heater) which is composed of a flange portion 2a and a pipe portion 2b in a lower portion of a heat storage tank 1. 2) is attached to the heater 2 and the heater 2 is energized to the outside of the flange 2a.
It was turned on and off by (hereinafter collectively referred to as protector 3).

In particular, the operating point for stopping the energization of the protector 3 is as shown in FIG. That is, energization is stopped only when the temperature of the temperature detector of the protector 3 reaches a preset value (this set value is 95 ° C. in the conventional example). Normally, the protector 3 is attached to the outside of the flange portion 2a for attaching the heater 2. Therefore, when water is supplied to the heat storage tank 1, the heater 2 is continuously energized. It never exceeded ℃. That is, the protector 3 does not operate during normal boiling of the electric water heater.

On the other hand, if water is not supplied to the heat storage tank 1 due to accidental misuse (hereinafter referred to as "empty"), the heater 2
When electricity is applied to the heater 2, the heater 2 remarkably generates heat and is damaged. However, the protector 3 is actuated in advance to stop the energization so as to avoid damage. At this time, as shown in FIG. 6, the heater 2 generates heat immediately after the start of energization, that is, the heat generated by the internal heating wire transfers to the pipe portion 2b, thereby raising the surface temperature of the flange portion 2a. The temperature detecting portion of the protector 3 which is in an electric heat relation with this portion is also gradually heated and operates so as to stop energizing the heater 2 when the set temperature is reached.

[0005]

However, in the above-mentioned conventional structure, the material forming the heater 2 is the heating wire and the pipe portion 2b in which the heating wire is embedded. Since the pipe portion 2b is made of stainless steel, the heater 2 is energized. After fever,
It takes time for the surface temperature of the flange portion 2a to rise due to heat transfer via the pipe portion 2b, and thus it takes a considerable time for the temperature detecting portion of the protector 3 to reach the set temperature. Meanwhile, the heater 2 having the heating wire inside continues to be heated. Then, the surface temperature of the pipe portion 2b of the heater 2 rises remarkably, and the heating wire of the heater 2 abnormally heats, thereby deteriorating the insulation performance of the filling material inside the pipe portion 2b, and thus the insulation resistance of the heater 2. However, there is a problem in that

The present invention solves the above-mentioned conventional problems. The detection of a blanking abnormality is discriminated based on the temperature rise near the heater and the time energization to the heater, and the energization is immediately stopped. The purpose is to reduce damage.

[0007]

In order to achieve the above-mentioned object, the present invention has a hot water storage tank for storing hot water and a heating wire inside, and the hot water stored in the hot water storage tank is supplied to the heating wire. Heating device configured to heat by the heat generation of the, a temperature detection device for detecting the temperature of the hot water stored in the hot water storage tank, the hot water temperature detected by the temperature detection device and the time after the heating device is energized A storage device that stores the value of a predetermined number of times, and a calculation device that substitutes the value stored in this storage device into a preset calculation formula to perform calculation.
It is provided with an identification device for comparing an arithmetic value calculated by this arithmetic device with a preset numerical value, and the electric current to the heating device is controlled by a signal from the identification device when an abnormality occurs due to emptying. It is an electric water heater.

[0008]

With the above-described structure, the present invention detects an abnormality due to emptying from a preset temperature rise in the vicinity of the heater and the amount of change in the energization time to the heater, so that energization to the heater can be reliably stopped in a short time. Come to do.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

In FIG. 1, reference numeral 1 is a heat storage tank provided with a heater 2 at its lower portion. Reference numeral 7 is a contact that can stop the energization of the heater 2 (hereinafter collectively referred to as a relay 7)
The operation of the relay 7 is controlled by a microcomputer (hereinafter referred to as the microcomputer 4). The microcomputer 4 receives a signal from a temperature detecting device 5 (hereinafter collectively referred to as a thermistor 5) and an integrated time sent from a time detecting device 6 (hereinafter collectively referred to as a timer 6) for detecting the energization time to the heater 2. Storage device 4c for storing the data of a predetermined number of times at predetermined intervals, and this storage device 4c.
The arithmetic unit 4a that performs the arithmetic operation for determining the presence or absence of empty space by substituting the value stored in the equation into a preset calculation formula, and the discriminating apparatus 4b that compares the arithmetic value with a preset numerical value. Is provided, and the power supply to the heater 2 is stopped based on the identification result.

The thermistor 5 is mounted on the outside of the flange portion 2a for mounting the heater 2, and heat is transferred to the pipe portion 2b and the flange portion 2a as shown in FIG. The rise can be detected.

CT is used to measure the integrated time of the timer 6, and the time when the current actually flows is detected. The storage device 4c and the arithmetic device 4a provided in the microcomputer 4 are shown in FIG.
As shown in, the change amount of the energization time T to the heater 2 and the temperature rise t, that is, the slope of the temperature rise of the heater 2 (ΔK = t /
T) and are calculated and stored. Such an operation is performed several times to store the change in the rise of the heater 2. On the other hand, the identification device 4b stores ΔK0 based on the preset microcomputer setting time T0 and the preset microcomputer temperature t0, and compares it with the temperature increase gradient ΔK of the heater 2. In other words, if the value is significantly larger (the tilt at the time of emptying, which is an abnormal state) compared to the normal boiling tilt,
The relay 7 is immediately instructed to stop the energization of the heater 2 by identifying that the heater 2 is energized before water supply.

The relay 7 simply turns on and off the energization, and its control is performed by the microcomputer 4.

[0014]

As described above, according to the electric water heater of the present invention, an abnormality due to emptying is detected from the temperature rise in the vicinity of the heater and the change amount of the energization time to the heater, so that it can be performed reliably and in a short time. It is possible to stop the energization to the heater, and it takes time for the temperature detection unit to reach the set temperature unlike the conventional example, and during that time the heater having the heating wire inside does not continue to heat. Therefore, the surface temperature of the heater does not rise remarkably, and it is possible to surely prevent the insulation resistance of the heater from lowering.

[Brief description of drawings]

FIG. 1 is a side view of an essential part of an electric water heater according to an embodiment of the present invention.

FIG. 2 is a side view of a heater portion of the electric water heater.

[Fig. 3] Energizing time of the electric water heater-temperature rise diagram of the flange part for mounting the heater

FIG. 4 is a side view of an essential part of an electric water heater of a conventional example.

FIG. 5 is a diagram showing a time period for energizing a conventional electric water heater-temperature rise in flange portion.

[Explanation of symbols]

 1 heat storage tank (hot water storage tank) 2 heater (heating device) 3 protector 4 microcomputer 5 thermistor 6 timer 7 relay

Front page continuation (72) Inventor Kenshi Akagawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A heating system having a hot water storage tank for storing hot water and a heating wire, wherein the hot water stored in the hot water tank is heated by the heat generated by the heating wire. A device, a temperature detection device that detects the temperature of hot water stored in the hot water storage tank, the hot water temperature detected by the temperature detection device, and the value of the time after the heating device is energized A storage device that stores only the value, a calculation device that substitutes the value stored in this storage device into a preset calculation formula to perform calculation, and an identification that compares the calculation value calculated by this calculation device with a preset numerical value An electric water heater comprising a device and controlling the energization to the heating device in the event of an abnormality due to emptying by a signal from the identification device.