| 摘要 |
PCT No. PCT/EP87/00604 Sec. 371 Date Jun. 2, 1989 Sec. 102(e) Date Jun. 2, 1989 PCT Filed Oct. 9, 1987 PCT Pub. No. WO89/03496 PCT Pub. Date Apr. 20, 1989.In a utility steam generator for small household electric appliances, steam pressure and filling water supply to the boiler is automatically controlled merely by a microswitch and a temperature controller, rather than by conventional devices such as pressure switches and maximum and minimum level controlling devices. The boiler body has a U-shaped pipe closed at both ends to form two legs, which are arranged on two superposed planes, so that the lower leg is the true boiler containing water and a heater and the upper leg is a steam dome. Control of steam pressure is effected by utilizing the variation of curvature of the pipe when the internal pressure varies, with a microswitch being used to switch the electric heating resistance on and off. The microswitch is mounted between the ends of the two legs of the U-shaped pipe, so the microswitch is closed by the two ends approaching one another when the pressure inside the pipe is reduced and the current is fed to the electric heater. The microswitch is opened, disconnecting the current supply, when the legs are spread apart a distance corresponding to the maximum pressure desired in the generator. The water feed pump is controlled by use of a thermostat, which can be arranged so the pump is actuated when the water level decreases and the pump is stopped when the mass on which the temperature controller is arranged cools down under the effect of the supply of cold water to the boiler. |
