JPH01234751A - Electric boiler - Google Patents

Abstract

PURPOSE:To obtain an electric boiler of a high efficiency at a stable temperature and pressure, by providing a control device which controls the duty factors of pulse control signals corresponding to the outputs from sensors that detect the temperature and pressure in a pressure vessel. CONSTITUTION:After amplified by an amplifier 9, the output from temperature detector 4 provided on a steam delivery pipe 1d is transmitted to a control circuit 10. Information on a specified temperature set by a setter 11 is recorded on the control circuit 10 which carries out a comparison of the temperature detected by the temperature detector 4 with the specified one. In case the detected temperature is lower than the specified one, the duty factor of the pulses issued from a pulse generator 8 is raised to increase the average period of time of power supply to an induction heating coil 3, and in case it is higher, the duty factor is lowered. The electric circuit 10 regulates the intermittent flows of high-frequency electric current from a high frequency electric source 6 through an intermittent circuit 7 by regulating the duty factor of pulses issued from the pulse generator 8. Thus, this allows a quick responsible and accurate controlling of induction heating with the indication heating coil 3.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to electric boilers.

[Conventional technology]

Conventionally, electric boilers using heating wires and the like have been proposed, but they have had problems in that they are not necessarily efficient, temperature and pressure cannot be adjusted quickly, and they lack stability.

[Problem that the invention seeks to solve]

The present invention was made to solve the above problems, and its purpose is to provide an efficient electric boiler with stable temperature and pressure.

[Means for solving the problem] The above purpose is to construct a part of the pressure vessel from a magnetic material, cover the outside with a heat insulating material, and further wind an induction heating coil around the outside. A circuit that controls the high frequency power supplied to the induction heating coil intermittently in response to a given pulse control signal, a sensor that detects the temperature or pressure inside the pressure vessel, and makes the output of the sensor match a predetermined set value. This can be achieved by an electric boiler characterized in that it is provided with a device for controlling the duty factor of the pulse control signal according to the output of the sensor.

[For production]

With the above configuration, the magnetic material constituting a part of the pressure vessel is efficiently heated by induction heating, and the average value of the high-frequency current supplied to the high-frequency induction coil is the same as the above-mentioned pulses that intermittent the high-frequency current. Since it can be easily adjusted by controlling the duty factor of the control signal, the temperature or pressure inside the pressure vessel can also be quickly controlled.

〔Example〕

Hereinafter, the Ichiki invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing one embodiment of an electric boiler according to the present invention, in which 1 is a pressure vessel, and 1a is an interior made of a corrosion-resistant and high-strength material such as stainless steel. container,
■b is a magnetic material wall provided on the outer periphery, 1c is a lid firmly fixed to the inner container 1a by bolts, etc., 1
d is a steam extraction pipe, 1e is a water supply pipe, 2 is a heat insulating material provided around the pressure vessel 1, 3 is an induction heating coil wound around the pressure vessel 1 via the heat insulating material 2, and 4 is an induction heating coil. A thermometer provided in the middle of the steam extraction pipe 1d, 5 a pressure gauge also provided in the middle of the steam extraction pipe 1d, 6 a high frequency power source, 7
1 is an intermittent circuit for intermittent current from a high frequency power source in response to pulses emitted from a pulse oscillator 8; 9 is an amplifier; 10 is a control circuit; and 11 is a setting device for setting a desired temperature or pressure.

The water in the pressure vessel l is heated by induction heating of the magnetic material wall 1b by the high frequency current supplied from the high frequency power supply 6 to the induction heating coil 3 via the intermittent circuit 7, and this heat is transferred through the inner vessel 1a. It is heated by being transmitted by

The high-frequency current supplied from the high-frequency power supply 6 to the induction heating coil 3 is intermittent in pulse form at a relatively low frequency by an intermittent circuit 7, and by changing the pulse width, the average The energization time is changed, and as a result, the magnetic material wall 1b is heated by the induction heating coil.
The amount of induction heating is increased or decreased.

The intermittent operation of the intermittent circuit 7 relies on pulses supplied from the pulse oscillator 8, and the duty factor of the pulses oscillated by the pulse oscillator 8 is controlled by the control circuit 10. .

The output from the thermometer 4 provided on the steam extraction pipe ld is amplified by an amplifier 9 and then sent to a control circuit 10. Information on the desired temperature set by the setting device 11 is recorded in the control circuit 10, and a comparison is made with the temperature detected by the thermometer 4. If the temperature is lower than the set temperature, the information is sent from the pulse oscillator 8. The duty factor of the oscillated pulse is increased and the average energization time to the coil 3 is increased, and conversely is decreased when the temperature is higher than the set temperature.

That is, the control circuit 10 controls the intermittent operation of the high frequency current from the high frequency power supply 6 via the intermittent circuit 7 by controlling the duty factor of the pulse oscillated from the pulse oscillator 8. When the detected temperature is lower than the set temperature, the pulse width from the pulse oscillator 8 is lengthened to increase the average energization time to the induction heating coil 3, and when it is higher than the set temperature, the pulse width is shortened. By doing so, the average energization time to the induction heating coil 3 is reduced, and thereby the amount of dielectric heating by the induction heating coil 3 can be controlled quickly and accurately.

The setting device 9 is composed of a potentiometer, an encoder, etc., and its set value is displayed and recorded in the control circuit 10.

Note that the magnetic material wall 1b has a larger hysteresis loss than a normal metal material, so that induction heating can be performed efficiently.

In the above embodiment, the amount of induction heating is controlled based on the temperature inside the pressure vessel, but it is also possible to control it based on the output of the pressure gauge 5.

〔Effect of the invention〕

Since the present invention is constructed as described above, it is possible to provide an efficient electric boiler with stable temperature and pressure.

The configuration of the present invention is not limited to the embodiments described above, but includes all modified embodiments that can be easily deduced by a person skilled in the art from the above description within the scope of the purpose of the present invention. It is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an embodiment of an electric boiler according to the present invention.

Claims (1)

[Claims] A part of the pressure vessel is made of a magnetic material, the outside of which is covered with a heat insulating material, and an induction heating coil is further wound around the outside of the pressure vessel, and the high frequency power supplied to the induction heating coil is controlled by a given pulse control signal. a circuit that performs intermittent control in response to the pressure, a sensor that detects the temperature or pressure inside the pressure vessel, and a duty factor of the pulse control signal according to the output of the sensor in order to match the output of the sensor to a predetermined set value. An electric boiler characterized by being provided with a device for controlling.