JP3414043B2 - Electric heating appliances - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a predetermined temperature in a heat appliance requiring a switch start memory which can be started arbitrarily or a switch self-holding function. Thereafter, the present invention relates to a general heating appliance that cuts off or delays energization, but specifically relates to an electric heating appliance having a boiling selection switch, which heats hot water or water in a container to boil it. . 2. Description of the Related Art In recent years, in order to bring out the taste and aroma of tea, coffee, black tea, etc., it has been generally attempted to remove the characteristic taste of tap water such as lime. It is widely known that tap water is boiled as a means of removing such a unique taste, and the odor of khaki cannot be completely removed unless boiling is continued for a long time, and the odor of khaki is converted to gas by boiling. It is intended to be released into the atmosphere together with steam. [0003] However, a conventional water heater called an electric pot heats water with a heater to perform water heating. However, in consideration of variations in the temperature of the water heater and other sensors, generally a boiling water is used to ensure safety. About 90 ° C. below the boiling point, and did not reach the boiling point. Therefore, there is a problem that the boiling water is not sterilized and cannot be used for milk for childcare. Even if the boiling point is detected, it is not possible to remove the smell of calcium unless heating is continued for a further two to three minutes. There is a problem that a complicated electronic circuit is required and the cost becomes high. [0004] Referring to FIG. 6, a boiling pot will be described as an example of a conventional electric heating apparatus which attempts to realize such an electric pot with an inexpensive relay circuit. In FIG. 6, reference numeral 1 denotes a switch for selecting the start of boiling, and 2 denotes a relay. When the switch 1 is pressed, it operates via a normally closed contact steam sensor 3 and at the same time the relay contact 4 is turned on. Is released, the relay circuit is held by itself. The contact 4 has a heater 5 for water heater.
Is connected, the electric kettle enters a water heater operation. When the hot water comes to a boil, steam is generated, the steam sensor 3 of the normally closed contact is operated, and the contact 4 is opened, so that the self-holding of the relay 2 is released and the heater 5 is stopped. [0006] As another conventional example, a configuration performed using an electronic circuit will be described with reference to FIG. Reference numeral 11 denotes a start switch for energizing the heater, and reference numeral 12 denotes a self-holding circuit for holding the relay 13 when the switch 11 is pressed. Reference numeral 14 denotes a temperature sensor for detecting a hot water temperature or a steam temperature. When the temperature sensor 14 detects a predetermined temperature, a temperature detection circuit 15 operates to drive the boiling maintenance timer 6. When the timer 6 expires, the reset circuit 7 resets the self-holding circuit 12 and turns off the relay 13.
Then, the heater 8 was stopped. The above specific circuit diagram will be described with reference to FIG. In FIG. 8, 21 is a start switch for energizing the heater, 22 is a self-holding circuit that self-holds the heater driving relay 23 when the switch is pressed, 24 is a temperature sensor for detecting temperature, 25 is a temperature detection circuit, and 26 is This is a timer circuit for securing a boiling time. Reference numeral 27 denotes a reset circuit that resets the self-holding circuit 22 when the timer circuit times out. [0008] However, a conventional electric heating device using the above-mentioned relay circuit is a steam sensor 3
Since the water heater 5 is shut off by the above operation, a sufficient boiling maintenance time cannot be secured, so that there is a problem that descaling and boiling sterilization cannot be sufficiently performed. There is also a problem that self-holding is released when an instantaneous power failure or the like occurs during water heating, and operation stops when power is restored. In the case of an electric heating device of an electronic circuit, descaling and boiling sterilization can be performed by providing a special timer circuit. However, since there is a problem in the reliability of the self-holding circuit 12 of the relay 13, there is a problem. For example, there is a problem that the relay 13 operates without permission. Originally, this type of operation switch is provided on the upper surface of the appliance so that it is easy to operate, but in the case of the conventional example, if only the switch is brought to the upper surface, it becomes easier for noise etc. to ride, and it is difficult to provide it separately from the circuit Had issues. In addition, the problem at the moment of an instantaneous power failure cannot be solved unless the power supply is backed up as in the conventional example, and the control circuit employing a microcomputer which is currently the mainstream of the boiling type electric water heater also has a problem. Since power supply backup does not match the cost, there was a similar problem at the time of a momentary power failure. An object of the present invention is to provide an electric heating appliance which solves the above-mentioned conventional problems. In order to solve the above problems, the present invention provides a heater, a temperature sensor for detecting a temperature of the heater, a temperature detecting means connected to the temperature sensor, and a first temperature detecting means connected to an output of the temperature detecting means . And the temperature detection means
The start switch connected in parallel with the second resistor and capacitor
A charging time constant means comprises a serial body of the capacitor charge and
Comparing means for comparing the electric voltage with the reference voltage of the reference voltage section, heater energizing means controlled by the comparing means,
The other end of the first resistor is connected to the second resistor and the capacitor.
Connected to the middle point of the
Starting storage means for charging and storing the capacitor, and after the temperature sensor has reached a predetermined temperature, the output of the temperature detecting means causes the first and second capacitors to be connected in parallel with the capacitor .
Consists discharge time constant means first resistor is connected, the voltage across the capacitor to delay the interruption of the heater energizing until drops to a predetermined reference voltage of the comparison means co
In addition, the storage of the start storage means is released . According to the above construction, the heater energizing means is started by operating the start switch, and the heater energizing means can be kept in the driving state by the start storing means charged in the capacitor. The output of the temperature detecting means which has detected a predetermined temperature allows the capacitor to be maintained at a low cost without a special timer circuit by using a discharge time constant circuit via a resistor. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an electric water heater as an electric heating device of the present invention, and FIG. 2 is a circuit diagram thereof. In FIG.
31 is a temperature sensor, and 32 is a temperature detecting means. Resistance 4
Reference numerals 1, 42, and 43 constitute a bridge circuit with the temperature sensor 31, and reference numeral 44 represents a comparison unit. A start switch 33 is a push button switch that does not lock. RM is a resistor, 34 is a comparing means, and a voltage dividing circuit of resistors 39 and 40 constitutes a reference voltage section 45. 35 is a Zener diode, and 36 is a start storage means. RT is a resistor, C is a capacitor 37 is timer means composed of C and RT, 38
Is a relay of heater energizing means. The operation of the electric water heater configured as described above will be described below. Here, assuming that the set temperature of the temperature detecting means 32 is determined to be the boiling temperature by the resistors 41, 42, and 43, and the temperature sensor 31 is currently set to 15 ° C., the output of the comparing means 44 becomes “HI” level. Therefore, the resistor RT is disconnected from the circuit. Also, the comparison means 3
Reference numeral 4 indicates that a reference voltage is determined by a voltage dividing circuit of resistors 39 and 40. Since the capacitor C has not been charged, the output of the comparing means 34 is "HI", and the relay 38 of the heater energizing means does not operate. Here, when the push button of the start switch 33 is pressed, the capacitor C is charged through the resistor RM, the charging voltage is clipped by the zener diode 35, and the variation in the charging voltage of the capacitor C due to the variation in the operation time of the start switch 33 is suppressed. . The charging voltage of the capacitor C is equal to the resistances 39 and 40.
When the voltage exceeds the reference voltage portion 45 determined by the following equation, the output of the comparison means 34 becomes "LOW" and the relay 38 is driven. Here, when the temperature of the temperature sensor 31 reaches the set temperature of the temperature detecting means 32 by energizing the heater, the output of the comparing means 44 becomes LO.
When the resistance becomes W, the resistor RT is connected in parallel with the capacitor C, and the charged charge is switched to discharge.
During this discharging, the relay 38 continues to be driven. When the potential of the capacitor C becomes lower than the reference voltage part 45 of the comparing means 34, the output of the comparing means 34 becomes "HI" and the relay 38 is cut off. . In this way, the operation of the start switch 33 is stored in the charging means of the capacitor C by the start storing means 36, and the relay 38 as the heater energizing means is activated. Further, when the temperature sensor 31 detects a predetermined temperature, the temperature sensor 31 is switched to a discharging means including a resistor RT and a capacitor C connected to the (output LOW) output of the comparing means 44 of the temperature detecting means 32, and the temperature sensor 31 detects the predetermined temperature. Even if it is detected, the driving of the relay 38 is delayed by a timer time composed of the discharging time constant by the resistor RT and the capacitor C. As a result, in the function of the electric water heater, the boiling time is secured, the descaling and sterilization effects of the hot water are obtained, and the start storage means 36 is automatically released by discharging the capacitor C in terms of circuit. A specific embodiment having such an operation will be briefly described with reference to FIGS. In FIG. 3, reference numeral 51 denotes a commercial power supply, 52 denotes a temperature fuse for ensuring safety during abnormal heating, 53 denotes a heater that is constantly energized, 54 denotes a heater for boiling water, and 55 denotes a boiling heater. This is a contact point of the relay 60 for controlling. Reference numeral 56 denotes a resistor for dropping a voltage from a commercial power supply, 57 denotes a diode for half-wave rectification, 58 denotes an electrolytic capacitor for smoothing, and 59 denotes a zener diode for constant voltage. Assuming that the boiling switch 67 is pressed, the capacitor 69 is charged through the resistor 68. The resistor 68 is a resistor having a small value for limiting a current flowing through the capacitor 69 when the capacitor 69 is charged.
Reference numeral 76 denotes a Zener diode for keeping the voltage of the capacitor 69 constant. This charging voltage is calculated by comparing the voltage divided by the resistors 65 and 66 by the comparing means 74. The emitter of the transistor 72 is connected to the comparing means 74 having an open collector output, and the relay 60 for controlling the boiling heater is connected to the collector. A temperature sensor 84 and a resistor 85 are provided at the base of the transistor 72.
The transistor 72 is turned on, the relay 60 is turned on, and the boiling heater is driven because the forward bias is applied via the resistor 73 at the divided voltage of FIG. 4. This state is shown in FIG. I have. The transistor 72 has another role, and also has a function of ensuring the safety by shutting off the power supply to the relay 60 in the event that the temperature-sensitive sensor 84 should be disconnected. Here, when the temperature sensor 84 detects the boiling point,
Since the resistance of the temperature sensor 84 is smaller than the voltage divided by the resistor 82 and the resistor 83, the divided voltage with the resistor 85 becomes higher, and the open collector output of the comparator 81 is turned on. The charged capacitor 69 has a timer function of discharging via the resistor 80. At this stage, the heater is still energized, and when the voltage across the capacitor 69 becomes lower than the divided voltage set by the resistors 65 and 66, the output of the comparing means 74 becomes O.
It becomes FF, the current of the transistor 72 is cut off, and the relay 60 is also turned off. Therefore, the heater 54 is turned off, and the heat retention is maintained only by the heat retention heater 53. That is, when the boiling switch 67 is turned on, the boiling start storage circuit operates by charging the capacitor 69 to select the start of boiling, and the ON state of the relay 60 is maintained. When the temperature sensor 84 detects boiling, a boiling detection output is output from the comparing means 81, and the charged capacitor 69 is discharged with the time constant of the resistor 80, and the time timer for removing the boiling sterilizing effect and the smell of slime is activated. . In this embodiment, an electric water heater has been described, but in a device in which the upper limit temperature of the temperature sensor cannot be set too high for safety reasons, the function of the present invention for delaying energization for a certain time after temperature detection is utilized. It can be solved by doing. The above control circuit can be used in an electric rice cooker as the electric heating appliance of the present invention. Some small-sized rice cookers of small-capacity size use cooked sensors using a conventional ferrite thermometer. By replacing such a fixed temperature sensor with a thermistor and changing the timer delay time of the control circuit of the present invention, it is possible to provide not only a control unit capable of freely setting the cooking condition, but also eliminating the need for a complicated mechanical mechanism. There is also a merit that the degree of freedom of the body design increases. FIG. 5 shows an embodiment in which the electric heating appliance of the present invention is used in a rice cooker, and its explanation will be described below. In FIG. 5, reference numeral 101 denotes a commercial power supply;
Is a thermal fuse for ensuring safety during abnormal heating, 103
Is a warming heater which is always energized, 104 is a rice cooker for cooking rice, and 105 is a contact point of a relay 110 for controlling the rice cooker. Reference numeral 111 denotes a diode for absorbing the back electromotive force generated from the coil of the relay.
106 is a resistor for dropping a voltage from a commercial power supply, 107 is a diode for half-wave rectification, 108 is an electrolytic capacitor for smoothing, and 109 is a Zener diode for constant voltage. Assuming now that the rice cook start switch 112 is pressed, the capacitor 114 is charged through the resistor 113. The resistor 113 is a resistor having a small value for limiting a current flowing through the capacitor 114 when the capacitor 114 is charged. Reference numeral 115 denotes a Zener diode for keeping the voltage of the capacitor 114 constant. This charging voltage is obtained by comparing the voltage divided by the resistors 116 and 117 with the comparing means 1
A comparison operation is performed at 18. The emitter of the transistor 119 is connected to the comparing means 118 having an open collector output, and the relay 1 for controlling the rice cooker is connected to the collector.
10 are connected. A forward bias is applied to the base of the transistor 119 via the resistor 122 at the temperature-divided voltage of the temperature sensor 120 for detecting the cooked food and the resistor 121, so that the transistor 119 is turned on.
The relay 110 is also turned on, and the rice cooking heater 105 is driven. The role of the transistor 119 is to operate the relay 110 when the temperature sensor 120 is disconnected.
Has the function of shutting off the power supply and ensuring safety.
Here, when the temperature sensor 120 detects that the cooked food has been cooked,
Since the resistance of the temperature sensor 120 is smaller than the voltage divided by the resistance 123 and the resistance 124, the divided voltage with the resistance 121 becomes higher, and the open collector output of the comparator 125 becomes ON. The charged capacitor 114 is discharged via the variable resistor 126. Therefore, when the voltage between both ends of the capacitor 114 becomes lower than the divided voltage set by the resistors 116 and 117, the output of the comparing means 118 is turned off, the current of the transistor 119 is cut off, and the relay 110 is turned off. Thereafter, the heater 104 is turned off, and the heat retention of the rice is maintained only by the heat retention heater 3. That is, when the rice cook start switch 112 is turned on, the capacitor 114 is turned on.
The rice cooking start storage circuit is activated by charging the
Is maintained in the ON state. When the temperature sensor 120 detects the cooked state, the output of the cooked state is output from the comparing means 125, and the charged capacitor 114 is connected to the variable resistor 1
Discharge via 26 resets the rice cooking start memory. Thus, it can be seen that the embodiment of the rice cooker shown in FIG. 5 and the embodiment of the pot shown in FIG. 3 can be realized with exactly the same configuration. The difference from the electric pot is that the resistance 80 of the electric pot shown in FIG. 3 is set to a relatively large value, whereas the variable resistance 126 is shown in FIG. 5 of the rice cooker. The variable resistor 126 is effective when adjusting rice offense and the like. As is clear from the above description, the control circuit of the electric heating apparatus according to the present invention, in particular, the electric water heater, enables the boiling operation to be arbitrarily performed only by temporarily pressing the boiling switch. A self-holding function with high performance can be established, and further boiling after the detection of boiling makes it possible to sterilize by boiling and to reduce the smell of chlorine. This operation is performed by using a circuit configuration that uses the charging and discharging of the capacitor without using a microcomputer.It is extremely resistant to malfunctions due to noise and the like. It is a highly reliable heater that can shut off the heater and has a large industrial value. Further, the electric heating appliance of the present invention is used for a rice cooker,
In addition to providing a control unit that can freely set the cooking time by changing the timer delay time, it also provides an excellent rice cooker that does not require a complicated mechanical mechanism and can increase the degree of freedom of the main body design You can do it.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an electric heating apparatus according to one embodiment of the present invention. FIG. 2 is a circuit diagram of the electric heating apparatus. FIG. 3 is a circuit diagram of an electric heating apparatus according to another embodiment of the present invention. FIG. 5 is a circuit diagram of an electric heating apparatus according to another embodiment of the present invention. FIG. 6 is a circuit diagram of a conventional example. FIG. 7 is a block diagram of another conventional example. EXPLANATION OF SYMBOLS 31 Temperature sensor 32 Temperature detection means 33 Start switch 34 Comparison means 36 Start storage means 37 Timer means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A47J 27/21 101 F24H 1/18 301 F24H 1/18 302

Claims (1)

(57) and [Claims 1. A heater, a temperature sensor for detecting the temperature of the heater, a temperature detecting means connected to the temperature sensor, first connected to the output of said temperature detecting means Resistance and
A start switch connected in parallel to the temperature detecting means;
Charging time constant means comprising a series body of a resistor and a capacitor ,
It has a reference voltage part for comparing with the charging voltage of the capacitor.
A comparison unit that, a heater through which is controlled by the comparison means
And the other end of the first resistor is connected to the second resistor in front of the second resistor.
Connect to the middle point of the capacitor and turn on the start switch.
Starting memory for storing the stored voltage by charging the capacitor
And charging the capacitor with the output of the temperature detecting means.
Discharge time constant means for discharging a voltage through the first resistor
A predetermined temperature depending on the charging voltage of the capacitor.
Is detected, the discharge time constant means is operated and the reference
The interruption of the heater energization is delayed until the voltage becomes equal to or lower than the predetermined voltage of the voltage section, and the storage of the start storage unit is released.
Electric appliances configured to be so .