JP2615923B2 - Electric water heater - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric water heater for heating and boiling a liquid contained in a container.

2. Description of the Related Art A conventional electric water heater has a circuit configuration as shown in FIG. In FIG. 2, 1 is an AC power supply, 2 is a heating element for heating the liquid in the container, 3 is a relay for controlling the energization of the heating element 2, and this relay 3 has a relay contact 3a and a relay coil 3b. It consists of. 4
Is a heating element for keeping heat, and the energization control of the heating element 4 for keeping heat is performed by a thyristor 5. 6 is a temperature sensing element for detecting the temperature of the liquid in the container; 7 is a control circuit for controlling the relay coil 3b and the thyristor 5;
3a is closed to cause the heat generating element 2 to generate heat, and the heat is maintained by the control circuit 7 controlling the thyristor 5 to be on and off depending on whether the temperature sensing element 6 is at or above a predetermined temperature.

Problems to be Solved by the Invention However, in such a conventional configuration, since both the heating element 2 for heating water and the heating element 4 for keeping heat are required, the cost is high, and the heating element 2 for heating water is required. The power consumption of the heat-generating heating element 4 is different by about one digit. Therefore, if both heating elements 2 and 4 are provided at the bottom of the container so that even a small amount of hot water can be used to maintain the temperature, the structure of the heating element becomes complicated. In addition, since there is no space, there is a problem that the wire diameter of the heat retaining heating element 4 is thin, easy to cut, and difficult to wind.

An object of the present invention is to provide an electric water heater that has solved such problems.

Means for Solving the Problems In order to solve the above problems, the electric water heater of the present invention connects a relay contact and a thyristor for controlling the energization of the heating element in parallel, and controls opening and closing of the relay contact during the water heating. An ON signal is output to the relay coil, and during the heat retention, an OFF signal is output if the temperature of the temperature sensing element for detecting the liquid temperature in the container is equal to or higher than a predetermined value. Is repeated so as to output a firing signal to the thyristor.

Operation The electric water heater of the present invention has the above-described configuration, so that water heating and heat retention can be performed by one heating element, so that the configuration of the heating element is simplified and reliability is improved. Moreover, it can be provided at a low cost.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In FIG. 1, 11 is an AC power supply, 12 is a heating element for heating the liquid in the container, and the capacity of the heating element 12 is 700W. Reference numeral 13 denotes a relay for controlling the energization of the heating element 12, and the relay 13 includes a relay contact 13a and a relay coil 13b. A thyristor 14 is connected in parallel with the relay contact 13a and controls the energization of the heating element 12. Fifteen
Is a temperature-sensitive element for detecting the temperature of the liquid in the container, 16 is a control circuit, and this control circuit 16 controls the relay coil 13b during water heating.
On the other hand, while maintaining the temperature, the thyristor 14 outputs an off signal if the temperature of the thermosensitive element 15 is equal to or higher than a predetermined value (here, 95 ° C.). In this case, the AC power supply 11 is turned on for one cycle and turned off for nine cycles.)
Thyristor 14
Is output to

Next, the operation of the circuit configuration of the above embodiment will be described. Water heating is performed by turning on the relay coil 13 in response to an ON signal of the control circuit 16, closing the relay contact 13a and energizing the heating element 12, and generating heat at 700W. When the temperature is maintained, the relay contact 13a opens, and if the temperature of the liquid in the container detected by the temperature sensing element 15 is 95 ° C or higher, the thyristor
14 is also off, but if it is less than 95 ° C, the control circuit 16
17 to the thyristor 14 and the thyristor 14
The ignition signal is output in synchronization with the power supply so that one cycle is turned on and nine cycles are turned off. As a result, the heating element 12 is 70W (700W
10%) to heat the liquid in the container and keep it warm.

According to the present invention, as is apparent from the description of the above embodiment, one heating element is used, the heating element is controlled by continuous energization by a relay contact during water heating, and intermittent by a thyristor during heat insulation. Since the heating element is controlled by energization, the configuration of the heating element is simplified, reliability is improved, and the cost can be reduced. Further, the current flowing through the thyristor is instantaneously large but its effective value is small, so that a thyristor of the same configuration as the conventional configuration can be used, and the thyristor is excellent in practicality.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an electric water heater showing one embodiment of the present invention, and FIG. 2 is a circuit diagram of a conventional electric water heater. 12 ... heating element, 13 a ... relay contact, 13 b ... relay coil, 14 ... thyristor, 15 ... temperature sensing element, 16 ... control circuit.

Claims (1)

(57) [Claims] 1. A heating element for heating a liquid in a container, a relay contact and a thyristor connected in parallel to each other and controlling the energization of the heating element, and a relay coil controlling opening and closing of the relay contact. A temperature-sensitive element for detecting the temperature of the liquid in the container, and an ON signal is output to the relay coil during water heating, and an OFF signal if the temperature of the temperature-sensitive element is equal to or higher than a predetermined value during warming, and if the temperature is lower than a predetermined value. For example, an electric water heater comprising a control circuit for outputting a firing signal to the thyristor so that the thyristor repeats on and off at a predetermined ratio.