JPH0566013A - Safety device for electric appliance - Google Patents

Abstract

PURPOSE:To secure the safety at a time when a temperature fuse fitted to the object for preventing overheat in a combustion instrument is replaced with a conductor in an emergent manner. CONSTITUTION:A current breaker 20 with a resistor 15 and a temperature fuse 19 installed near a heating apparatus and a controller 18 stopping the combustion of the heating apparatus when the current breaker 20 is opened and when electric resistance between connecting terminals 23, 24 takes a value except a fixed value are provided. Accordingly, the safety of an electric appliance is maintained even when the current breaker is replaced with a conductor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for an electric appliance which detects overheating caused by leakage of combustion gas and stops burner combustion.

[0002]

2. Description of the Related Art FIGS. 4a and 4b show the structure of a conventional gas instantaneous water heater, in which water is supplied from a water inlet 1 and passes through a water quantity valve 2 for adjusting the water quantity, and heat is absorbed by a heat exchanger 3. Hot water is supplied from the hot water supply port 4 to the outside of the device. Gas is supplied from the gas inlet 5,
It is supplied to the burner 7 from a gas proportional valve 6 for adjusting the gas amount. The air required for combustion is supplied by a blower 8 for combustion, and the air and the gas are burned by the burner 7 to heat the heat exchanger 3 and then discharged to the outside from the exhaust port 10 of the exhaust unit 9. Further, when the ambient temperature between the heating device 11 in which the burner 7, the heat exchanger 3 and the exhaust part 9 are airtightly joined and the heat shield plate 13 provided inside the outer casing 12 of the body becomes equal to or higher than a predetermined temperature, the fusing occurs, A temperature fuse 17 as a temperature detector for stopping the operation of is attached to the heat shield plate 13 or the like.

[0003]

However, as a problem with the above configuration, when the thermal fuse 17 is blown, the thermal fuse 17 is replaced with a conductive wire of a substitute as a first aid, and the instrument is operated. There is a risk that even if overheating occurs, the conductive wire will not be cut and a dangerous state will be brought about.

Therefore, an object of the present invention is to provide a safety device such as a combustion appliance which cannot operate when the thermal fuse is replaced with a conductive wire.

[0005]

In order to achieve the above object, the means of a safety device according to the present invention is such that a temperature fuse that fuses at a predetermined temperature to cut off a current and a resistor connected to this temperature fuse are integrally molded. However, it is equipped with a current circuit breaker with a rated resistance, a connection terminal of the current circuit breaker, and a safety device that cuts off the drive signal of the appliance when it receives an unrated resistance due to the connection of a substitute of the current circuit breaker to the connection terminal. It is a thing.

[0006]

With the above-described means, the safety device of the present invention is safe even if a replacement product is connected to the connection terminal without using a genuine replacement product of the current breaker when the current breaker is blown by a predetermined temperature. The instrument detects the unrated resistance of the replacement and shuts off the drive signal of the instrument. Since the current breaker has a rated resistance, it is difficult to use it as a substitute, and it is possible to eliminate the unsafe use of the device due to the use of the substitute.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a water heater and its safety device as an embodiment of the present invention. The same parts as those of the conventional example shown in FIG. 4 are designated by the same reference numerals and have the same names and the same functions. I shall. The modified part different from the prior art will be described below. The controller 18, which is a safety device, is connected to the current breaker 20 via the connection terminals 23 and 24. The current breaker 20 is composed of a resistor 15 having a fixed current resistance and a temperature fuse 19 which cuts off the current so as not to lose the function of electric conduction by melting at a predetermined high temperature and molded integrally with cement or the like. It has lead lines 21 and 22. The rated resistance R _S based on the variation between the parts of the current breaker 20 is made up of the sum of the resistance value of the resistor 15 and the connection resistance including the temperature fuse 19. Controller 18
Serves to stop the combustion of the burner 7 when the connection resistance R _f of the connection terminals 23 and 24 is other than the rated resistance R _S. When the burner 7 is ready for combustion and the combustion gas is supplied, when the signal for turning on the transistor 25 is output from the sequence control circuit unit 16, the coil 17 of the gas proportional valve 6 for sending the gas fuel to the burner 7 is output. A predetermined voltage is applied from a power supply 26 through a current fuse 20 and a temperature fuse 30 separately provided in the controller 18 and a transistor 25. Then, the gas proportional valve 6 is opened, the gas fuel is sent, and the burner 7 is burned.

When a small hole is generated in the heating device 11 due to local overheating or the like and the combustion gas leaks, the temperature fuse 19 of the current breaker 20 is heated and blown by the leaked gas. Subsequently, the voltage applied to the coil 17 of the gas proportional valve 6 disappears, the supply of fuel gas is stopped, and the heating of the heating device 11 is also stopped. In this way the danger of fire etc. is avoided. If you notice a malfunction of the equipment, repair the defective part of the small hole of the heating device 11, replace the current breaker 20 with another genuine part, and check whether the repaired part is repaired as prescribed or the prescribed standard after repair is It is possible to restart safe operation after confirming that the conditions are satisfied.

In spite of this, in the case where the genuine parts are not prepared and the case is urgent, as an alternative, a conductive wire 27 using a conductive wire having a simple resistance and a small resistance is used as the connecting terminal 23,
24 may be connected. At this time, the voltage detector 2
Numeral 8 detects the voltage due to the value of the connection resistance R _f other than the rated resistance R _S , heats the heater 31 connected to its output terminal 29, and the heat causes the thermal fuse 30 installed in the controller 18 to be detected. Melt down. The current breaker 20 is the heating device 11
There is a limit to the mounting position for the purpose of detecting the temperature of
The thermal fuse 30 is installed at a site that cannot be easily replaced at the time of fusing, and is configured so as to invalidate the alternative treatment of non-genuine parts.

The voltage V detected by the voltage detector 28_iIs the contact
Let R be the resistance connected to the connection terminals 23 and 24, and be proportional to the gas.
Electric resistance R of coil 17 of valve 6_L, Of the transistor 25
ON resistance is R_ON, The DC power supply voltage of the power supply 26 is V_CTo
When voltage between terminals 23 and 24 Voltage V_iIs a transistor
When 25 is ON, V_i= V_C・ R / (R_f+ R_L+
R _ON). Now V_C= 20V, R_L= 90Ω, R_ON
= Resistance value R when 5Ω and voltage V between terminals 23 and 24_iof
The relationship is shown in FIG. The voltage comparator 28 is a transistor
It is detected from the terminal 29 that the data 25 is ON, and
At this time, as shown in FIG. 3B, the resistance R is 0Ω to 4Ω (Rf
₁6) to 200Ω (Rf₂Of)
As mentioned above, the heater 31 is heated at the output terminal 29.
Output H is generated. Resistance R is 200Ω or more (Rf₃
, And does not have an output H for heating the heater 31
When the current breaker 20 melts, the temperature
This is to prevent the fuse 30 from being blown out.
It Rf at the same time₃Even if the electric resistance of is mistakenly connected,
Since the current flowing through the coil 17 of the gas proportional valve 6 is small,
The electric current does not open the gas passage, which is a safety issue.
Because there is no. The operating point of 200Ω becomes the operating point of 1KΩ
Even if it changes, it has the same effect.

However, even if the resistance R is Rf ₃ , the heater 31
When it comes to have an output H that heats the
When 0 melts, the thermal fuse 30 also melts. Therefore, even if the current breaker 20 is replaced with a conductive wire after that, the appliance cannot be operated. In this case, safety is secured, but
Even if the current breaker 20 is replaced with a genuine part, there is a problem that the appliance cannot be operated. Even if the current breaker 20 is cut due to a temporary water supply abnormality in the water heater, the convenience of being unable to be repaired simply by replacing the normal appliance with a genuine part is lacking.

Contrary to this, in the method of the embodiment, when the current breaker 20 is blown due to temporary overheating, the temperature fuse 30 does not blow because the output of the voltage comparator 28 is L, and the rated resistance R
_It can be repaired by replacing it with an _S (= 4 to 6Ω) genuine part.

When the resistors R are Rf ₁ and Rf ₂ , the voltage comparator 28 produces an output H for heating the heater 31,
If a conductive wire or the like having a resistance between them is used instead of the current breaker 20, the heating of the heater 31 melts the temperature fuse 30, and the combustion operation of the appliance is stopped. When the resistance R is the rated resistance R _S , the output of the voltage comparator 28 is naturally L. Then, the rated resistance R _S is equal to the connection terminals 23, 2
Not only the low resistance value of the conductive line 27 as a substitute for short-circuiting between the four, but also the choice width is suppressed to a small range (4 to 6Ω) even if other resistors are intentionally selected, and the substitute is used. Has the effect of suppressing The safety device of the present invention detects the other voltage based on the resistance R between the connection terminals 23 and 24, and replaces the temperature fuse 30 and the heater 31 with the coil 17.
A switch that shuts off the current circuit may be used.

[0015]

As is apparent from the above description, in the safety device according to the present invention, when the overheat-preventing temperature fuse is blown, or when the thermal fuse terminals are connected by a substitute such as a conductive wire, an emergency measure is taken. Also, since the electric appliances cannot be continuously operated, the safety against illegal use can be maintained.

[Brief description of drawings]

FIG. 1 is a control circuit diagram of an embodiment of a safety device of the present invention.

FIG. 2 is a sectional configuration diagram of the same.

[FIG. 3] (a) is a characteristic diagram of the voltage input of the same voltage detector, and (b) is a characteristic diagram of the same control output.

FIG. 4A is a side sectional view showing a conventional water heater, and FIG. 4B is a front sectional view showing the same.

[Explanation of symbols]

 15 Resistor 19 Thermal Fuse 20 Current Breaker 23, 24 Connection Terminal 27 Conductive Wire (Alternative) 30 Thermal Fuse (Safety Device) 31 Heater (Safety Device)

Claims (1)

[Claims] 1. A temperature fuse that fuses and cuts off current at a predetermined temperature and a resistor connected to the temperature fuse are integrally molded, and a current breaker having a rated resistance, a connection terminal of the current breaker, and a connection terminal are provided. A safety device for electrical equipment, which is equipped with a safety device that shuts off the drive signal of the equipment when it receives an unrated resistance due to the connection of the substitute of the current breaker.