Electric heating – Heating devices – With power supply and voltage or current regulation or...
Patent
1999-07-26
2000-10-24
Paschall, Mark
Electric heating
Heating devices
With power supply and voltage or current regulation or...
219519, 219481, 219486, 324418, 361160, H05B 102
Patent
active
061370916
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a heat-adjustable electric cooker employing a plurality of heaters.
BACKGROUND ART
FIG. 9 shows a structure of a generally known heat-adjustable electric cooker employing a plurality of heaters.
In FIG. 9, the cooker comprises heaters 31 and 38, heat-adjuster 32 and 39 employing bimetal for adjusting heat, commercial power 33, warning lamp 34 for indicating the heater is ON, switches 35 and 40 incorporated in the heat-adjuster, bimetallic switches 36 and 41 on a control side, sub-heaters 37 and 42 for heating the bimetal and being connected to heaters 31 and 38 in series. Sub-heaters 37 and 42 are incorporated into switches 36 and 41 on the control side.
Heat of this electric cooker is adjusted in this way: bimetallic switches 36 and 41 are heated by sub-heaters 37 and 42, and the switches 36 and 41 interlock switches 35 and 40 to open or close thereof.
The conventional construction employing bimetal has the following problems: (a) a wide range of performance dispersion of bimetal in respective products are expected, (b) various types of bimetal responsive to wattage of respective heaters must be prepared in order to minimize the difference in heat value, (c) and thus fine controlling is needed, (d) a great amount of heat dissipation is wasted due to a long control duty (e) heat is applied to food with low efficiency, (f) from the view point of service life of the electric cooker, contact points must be replaced periodically due to insufficient durability, and (g) in a case of a large size appliance such as built-in type cooker in a system kitchen, a large number of heaters make the replacement cumbersome and time-consuming work, which produces serious problems in maintenance.
DISCLOSURE OF THE INVENTION
The present invention addresses the problems discussed above, and the first object is to provide an electric cooker having the following advantages: stable performance can be expected in each product, a product free from being matched with a heater, and a product having a contact point of excellent durability and expecting easy replacement or maintenance-free.
The second object is to provide an electric cooker having a controller that can reduce the chances of forming deposition on contact points of relay.
The third object is to provide an electric cooker that can heat food efficiently and perform fine control over the heat.
The fourth object is to provide an electric cooker that can forcibly halt the operation of the cooker when the contact point issues a maintenance warning or shows its end of service life so that safety of the cooker can be ensured.
The fifth object is to provide an electric cooker that has an inexpensive memory storing the safety status before a power failure.
The electric cooker of the present invention comprising the following elements: based on a signal from the detector when the contact point is deposited; the signals to the controller.
The controller controls the plurality of relays based on a signal from 0 (zero) volt-detector. The signal is used for ON/OFF the contact points at near 0 (zero) potential. The controller also controls the heat of the respective heaters. Since the controls of ON/OFF of relays and the heat at the plurality of heaters are practiced based on the signal from a zero-volt-detector, stable and reliable control can be practiced for a long time.
The electric cooker of the present invention includes a polarity switch that controls ON/OFF of the contact point by using the transition points from/to negative area to/from positive area of the commercial power based on a signal from the deposition detector that detects deposition on the respective ends of the contact points. The positive and negative potentials of an alternating current can be used for ON/OFF the contact point, the deposition on contact points can be thus restrained, and therefore the service life of the contact point can be substantially extended.
The electric cooker of the present invention includes an automatic cycle switch that switches a
REFERENCES:
patent: 4389691 (1983-06-01), Hancock
patent: 4959746 (1990-09-01), Hongel
patent: 5243291 (1993-09-01), Umemura
Int'l Search Report for Int'l Appln No. PCT/JP98/05187 dated Feb. 16, 1999.
English translation of Form PCT/ISA/210.
Kikuoka Mitsuhiko
Shibata Satoru
Matsushita Electric - Industrial Co., Ltd.
Paschall Mark
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