JPH10281457A - Bimetal type sensor for preventing over-heating of tempura-oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rust or corrosion of bimetal, attain a long service life of the product and realize a high reliability in operation of the product. SOLUTION: This tempura oil fire-preventing sensor is fixed to a gas equipment having a thermo-couple and a gas opening or closing valve for opening or closing a gas supplying passage for a gas burner. When a temperature of a bottom part of a cooking device reaches a predetermined constant temperature, a driving current of the gas opening or closing valve is shut off to terminate supplying of gas. In this case, there are provided a main body case 26 and a cap 25 covered on the main body case 26 so as to detect heat while being contacted with the bottom section of the cooking device. Within the main body case 26 are stored a switch (for example, a reed switch 20) inserted into a driving circuit of the gas opening or closing valve, a bimetal 15 arranged inside the cap 25, and a switch driving means driven by a repelling force of the bimetal 15 so as to turn on/off the reed switch 20. A resin film 22 made of polyimide resin is applied to cover the bimetal 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used for various gas appliances such as a cooking gas table. In particular, when cooking a tempura or the like using a gas appliance, it is caused by overheating of the tempura oil. The present invention relates to a bimetallic tempura oil overheating prevention sensor (hereinafter, also simply referred to as a "tempura oil overheating prevention sensor") capable of preventing a fire from occurring.

[0002]

2. Description of the Related Art A conventional bimetallic tempura oil overheat prevention sensor will be described below with reference to the drawings. §1: Description of the conventional example ... refer to FIG. 6 FIG. 6 is an explanatory view of the conventional example. FIG. 6A is an overall view of the gas appliance, FIG. B is a switch-on state, and FIG. In the conventional example shown in FIG. 6, when a predetermined overheating temperature is detected by the thermo-responsive element, the excitation circuit of the solenoid valve provided in the gas supply passage is shut off to prevent overheating of the tempura oil, thereby preventing a fire caused by the tempura oil. What to prevent (Japanese Unexamined Patent Publication No. Hei 3-2365)
No. 20) and is configured as shown.

As shown in FIG. 6A, a gas appliance is provided with a gas burner 3 for cooking, a gas supply pipe 11 for supplying a fuel gas to the gas burner 3, and a part of the gas supply pipe 11. A solenoid valve 10 for turning on / off a gas supply amount,
A thermocouple 5 that generates an electromotive force by the heat of the flame 4 of the gas burner 3 and a thermoresponsive element 12 (a tempura oil overheat prevention sensor that drives a switch 14 in accordance with the temperature of the bottom of the pan 1 placed on the gas burner 3. Alternatively, a tempura oil fire prevention sensor) is provided.

[0004] The thermoresponsive element 12 includes a bimetal 15.
And the force transmitting means 1 driven by the bimetal 15
3 is provided, and a switch 1 is provided by the force transmitting means 13.
4 is driven. In this case, the switch 14 is turned on during normal cooking, and an electromotive force is generated in the thermocouple 5 by the heat of the flame 4, and the electromagnetic valve 10 is driven by the electromotive force, so that the gas is supplied to the gas burner 3. Is being supplied.

In this state, the temperature of the bottom of the pot 1 is lower than a predetermined temperature, the bimetal 15 is in an upwardly convex state as shown in FIG. It keeps the switch on without contact. However, when oil 2 is overheated and reaches a certain temperature, bimetal 1
5 is inverted as shown in FIG. 6C and deformed into a downwardly convex state, pushing the force transmitting means 13 downward to open the switch 14 and shut off the switch 14.

Therefore, the excitation circuit of the solenoid valve 10 is shut off, so that the solenoid valve 10 shuts off the gas supply passage and stops the supply of gas to the gas burner 3. In this way, overheating of the tempura oil can be prevented, and a fire due to the tempura oil can be prevented.

In this example, since the force transmitting means 13 is driven by utilizing only the deformation of the bimetal 15, the stroke of the force transmitting means 13 is small, and the switch 1 is securely connected.
Driving 4 requires precise processing accuracy and assembly accuracy of other members. Further, the inversion displacement amount of only the bimetal 15 changes depending on the diameter of the bimetal. For example, the displacement amount of the bimetal having a diameter of about 20 mm is 0.5 to
It is about 1.0 mm, which is extremely small.

[0008]

As described above, the prior art has the following problems. (1): The tempura oil overheat prevention sensor is installed almost at the center of the gas burner for cooking, and is exposed to gas generated by combustion and salt water vapor (miso soup, various kinds of cooking juice) due to boiling during cooking. Used in the environment. For example, a small amount of SO from a gas burner due to gas combustion
₂ (Sulfurous acid) gas, H ₂ S (hydrogen sulfide) gas, etc. are generated, and juice containing various kinds of salt water spills out of the pot, and salt steam may be generated.

[0009] Bimetal elements used in such an environment are rusted or corroded under the influence of harmful components of the gas or steam containing salt water. For this reason, the life of the bimetal has been significantly shortened.

(2): It is conceivable to apply metal plating or the like to the bimetal element itself in order to prevent corrosion. However, the reaction characteristics of the bimetal deteriorate, and the function as a sensor for preventing overheating of the tempura oil is hindered.

(3): It is technically difficult to make the whole tempura oil overheating prevention sensor a hermetically sealed structure because of direct contact with the flame. The present invention solves such a conventional problem, and realizes a longer life and higher reliability of a bimetal-type tempura oil overheat prevention sensor by preventing rust and corrosion of the bimetal. Aim.

[0012]

FIG. 1 is an explanatory view of the principle of the present invention. FIG. 1A is an explanatory view of a bimetal, FIG.
Diagram C shows state 2. The present invention is configured as follows to achieve the above object.

That is, a gas appliance comprising a thermocouple heated by the combustion of gas by a gas burner to generate an electromotive force, and a gas on-off valve driven by the electromotive force of the thermocouple to open and close a gas supply path to the gas burner. When the temperature of the bottom of the cooking utensil reaches a predetermined temperature, the bimetal-type tempura oil overheat prevention sensor cuts off the drive current of the gas on-off valve to stop gas supply. And a cap 25 that covers the main body case 26 and is in contact with the bottom of the cooking utensil and is heat-sensitive. The main case 26 includes a switch (for example, a reed switch 20) inserted into a drive circuit of the gas on-off valve, and a cap 25.
And a bimetal 15 arranged inside the
A switch driving means (for example, a driving means including an armature 32 and a magnet 35) for driving the switch with the reversing force is accommodated, and the bimetal 15 is covered with a resin film 22 of a polyimide resin.

(Operation) The operation of the present invention based on the above configuration will be described with reference to FIG. The tempura oil overheat prevention sensor 17 operates as follows while being attached to the gas appliance. At the time of normal cooking, cooking is performed by putting oil in a cooking utensil. In this state, the bimetal 15 is in a state of being convex upward. At this time, the armature 32 is not driven by the bimetal 15, and a gap of a certain length is formed between the bimetal 15 and the convex portion 37 of the armature 32.

For this reason, the distal end P of the long side of the armature 32 is pressed against the end of the yoke 42 by a return spring, and the distal end P and the yoke 42 are in contact with each other, so that a gap is formed between them. Not formed. Therefore, the reed switch 20 is turned on by the magnetic flux from the magnet 35 (see state 1 shown in FIG. 1B).

After that, when the temperature of the oil rises and the bottom of the cooking utensil reaches a predetermined constant temperature, the bimetal 15 is instantaneously inverted to be in a convex state (snap action operation). The projecting portion 37 provided on the armature 32 is pressed downward by the instantaneous force when the bimetal 15 is inverted. At this time, the armature 32 is movable on a convex portion provided at the end of the hole 38, moves against the return force of the return spring, and separates the tip P from the yoke 42. For this reason, a gap is formed between the tip end P of the armature 32 and the yoke 42.

As a result, the magnetic flux supplied to the reed switch 20 is cut off, and the reed switch 20 is turned off (see state 2 shown in FIG. 1C). When the reed switch 20 is turned off in this manner, the coil of the solenoid valve is de-energized, and the solenoid valve shuts off the gas supplied to the gas burner. For this reason, the flame of the gas burner is extinguished, and the temperature of the oil in the cooking utensil decreases, preventing a tempura oil fire. Thereafter, when the temperature of the oil in the cooking utensil falls to a predetermined value, the bimetal 15 returns to its original state (a state of upward projection). Therefore, the armature 32 returns to the original position by the return force of the return spring.

The entire surface of the bimetal 15 is covered with a resin film 22 made of a polyimide resin. The polyimide resin film 22 is excellent in heat resistance, gas resistance, salt water resistance and the like, and functions as a protective film for preventing rust and corrosion of the bimetal. Therefore, even when the bimetal 15 is exposed to gas, salt water vapor, or the like, the metal constituting the bimetal 15 is not affected. Therefore, rust and corrosion of the bimetal 15 can be prevented.

As described above, since the bimetal 15 is covered with the resin film 22 of the polyimide resin,
5, the gas resistance and salt water resistance are improved. As a result, rust and corrosion of the bimetal 15 can be prevented, and a longer life and higher reliability of the product can be realized.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings. It should be noted that "upper,
Or, "upper", "lower, or lower" are descriptions in a state where the tempura oil overheat prevention sensor is attached to the gas appliance, respectively.

§1: Description of gas appliance ... see FIG. 2 FIG. 2 is an explanatory diagram of the gas appliance, A is an overall view of the gas appliance, and B is a circuit diagram. Hereinafter, a gas appliance with a tempura oil overheat prevention sensor will be described with reference to FIG.

As shown in the figure, a gas appliance (for example, a gas table for cooking) has a gas burner 3 for burning fuel gas (hereinafter simply referred to as "gas") and a gas for supplying the gas to the gas burner 3. A gas supply pipe 11, a solenoid valve 10 provided in a part of the gas supply pipe 11 to turn on / off a gas supply amount, an ignition button 7 for igniting gas from the gas burner 3, and a gas from the gas burner 3. A thermocouple 5 for generating an electromotive force by the heat of the flame 4 and a sensor 17 for preventing overheating of the tempura oil which comes in contact with the bottom of the pot 1 placed on the gas burner 3 are provided.

The tempura oil overheat prevention sensor 17
A reed switch 20 is provided therein, and the reed switch 20 is always turned on by a magnetic flux from a magnet. The solenoid valve 10 is provided with a coil 18 for driving the valve.
The excitation current is supplied via the reed switch 20 which is always on by the generated electromotive force (connected at the time of assembling the gas appliance).

That is, the thermocouple 5 and the always-on reed switch 2 provided in the tempura oil
0 and the coil 18 of the solenoid valve 10 form a closed loop. Therefore, when the cooking is started, the flame 4
Is generated and the thermocouple 5 is heated, an electromotive force is generated in the thermocouple 5, and the electromotive force causes the reed switch 2 in the ON state to be turned on.
An exciting current flows through the coil 18 through the coil 0 and the solenoid valve 10 is driven.

In this case, the solenoid valve 10 opens when the reed switch 20 is turned on and an exciting current flows through the coil 18, and supplies gas from the gas supply pipe 11 to the gas burner 3. However, the reed switch 20 is turned off and the coil 1
When the exciting current to the gas supply line 8 is cut off, the valve closes and the gas supply pipe 1 is closed.
The supply of gas from 1 to the gas burner 3 is stopped.

When cooking the tempura using the gas appliance having the above-described configuration, the pot 1 containing the oil 2 for the tempura is placed on the gas burner 3, and the solenoid valve 10 is opened by operating the ignition button 7 to open the gas supply pipe. Gas is supplied to the gas burner 3 from 11 and the gas is ignited. When the gas is ignited, an electromotive force is generated in the thermocouple 5 by the heat of the flame 4, and the coil 18 of the electromagnetic valve 10 is excited by the electromotive force, so that the electromagnetic valve 10 opens the gas supply pipe 11 to continue the gas supply. Do it.

Therefore, the gas burner 3 continuously burns the gas, and the gas flame 4 generated at that time causes the oil 2 to burn.
Raise the temperature and cook tempura. Thereafter, when the temperature of the oil 2 rises and the temperature of the bottom of the pan 1 rises to a predetermined constant temperature, the tempura oil overheat prevention sensor 17 is activated, and the internal reed switch 20 is turned off. At this time, the exciting current to the coil 18 is cut off, the solenoid valve 10 is de-energized, and the valve is closed. Therefore, the supply of gas from the gas supply pipe 11 to the gas burner 3 is stopped to prevent overheating of the tempura oil.

§2: Description of tempura oil overheat prevention sensor
3 and FIG. 4 FIG. 3 is an exploded perspective view of a tempura oil overheating prevention sensor, and FIG. 4 is an explanatory view of parts. Hereinafter, the tempura oil overheat prevention sensor 17 will be described with reference to FIGS.

As shown in FIG. 3, the tempura oil overheat prevention sensor 17 includes a main body case 26 and a cap 25 which covers the main body case 26. The entire surface of the main body case 26 is coated with a polyimide resin. Armature 32 to which magnet 35 is fixed, holder 30 having hole 38 into which armature 32 is inserted, yoke 42 and reed switch 20
, A coil spring 31, a cylindrical shaft 28 having a spring receiver 29, and the like. Hereinafter, each of the components will be described in detail.

(1): Description of the cap 25 The cap 25 is used to cover the main body case 26. When the tempura oil overheat prevention sensor 17 is used, the pan 1
The heat is sensed in contact with the bottom. The upper portion of the cap 25 (the surface that contacts the pot 1) is formed to be substantially flat and circular, and the flat portion is a portion that contacts the bottom of the pot 1. Further, a peripheral portion of the cap 25 is fixed to the main body case 26 in a state of being in contact with an outer peripheral portion of the main case 26, and a convex portion for locking with a concave portion on the main body case 26 side is formed inside. ing. The cap 25 is made of stainless steel, phosphor bronze, or the like.

(2): Description of the main body case 26 The main body case 26 is composed of a hollow cylindrical large-diameter portion 26A and a small-diameter portion 26B and has a step 36 between the large-diameter portion 26A and the small-diameter portion 26B. In this case, each component constituting the tempura oil overheat prevention sensor 17 is housed. The main body case 26 is used in a state in which the above-mentioned components are housed therein and then covered with the cap 25. In a state where the cylindrical shaft 28 housed inside is fixed to a gas appliance, the main body case 26 The cap 25 is configured to be able to move up and down by pressing the cap 25 at the bottom of the pan 1. That is, the main body case 26 is configured to move up and down depending on the type of the pan.

Further, on the open end side (upper side) of the large-diameter portion 26A of the main body case 26, a concave portion for engaging with the convex portion of the cap 25 is formed. Are fitted so as to fix both. The body case 26 is made of stainless steel, phosphor bronze, or the like.

(3): Description of Bimetal 15 The bimetal 15 is arranged so as to be in contact with the inside of the cap 25, and is inverted (deformed) according to the temperature of the bottom of the pot 1. In this case, the bimetal 15 is formed in a disk shape, and is always upwardly convex (convex inward of the cap 25).
It has become. That is, the center of the bimetal 15 is in contact with the substantially center of the inside of the cap 25, and the periphery of the holder 3 is slightly away from the inside of the cap 25.
0 is supported at the open end. When the temperature of the bottom of the pan 1 reaches a predetermined temperature, the bimetal 15
Is inverted from the upwardly convex shape to a downwardly convex state (snap action action).

As shown in FIG. 4A, the bimetal 1
5 has a polyimide resin coating on the entire surface. That is, the entire surface of the bimetal 15 is covered with a resin film 22 made of a polyimide resin. The resin film 22 is formed, for example, by spraying a polyimide resin liquid on the entire surface of the bimetal 15 and then baking the polyimide resin.

The polyimide resin film 22 is excellent in heat resistance, gas resistance, salt water resistance and the like, and functions as a protective film for preventing rust and corrosion of the bimetal. Therefore, by coating the entire surface of the bimetal 15 with the polyimide resin as described above, the bimetal 15 is prevented from being rusted or corroded.

In this case, the resin film 2 made of a polyimide resin
If the thickness t is too small, the protective effect is reduced,
If the thickness is too large, the thermal conductivity becomes poor and the sensitivity of the bimetal becomes low. Therefore, as a result of the test, the thickness t is t = 8 to 15
It has been found that a range of μm is a preferable thickness. That is, the thickness t = 8 to 15 μm on the entire surface of the bimetal 15.
By coating the resin film 22 with a certain degree of polyimide resin, gas resistance, salt water resistance and the like are improved, and the rusting and corrosion of the bimetal 15 can be prevented.

(4): Description of the armature 32 The armature 32 uses a clad metal in which the magnetic body portion 45 and the non-magnetic body portion 46 are formed in a band shape, and is placed at a certain position (movable center position during operation). ) And bent into a substantially L-shaped yoke composed of a long side and a short side. And
Outside the short side of the armature 32 (bimetal 15
Side) is provided with a convex portion 37 (a portion in contact with the bimetal 15) driven by inversion of the bimetal 15,
On a part of the inside of the long side (the reed switch 20 side),
Magnet storage section 47 for storing magnet 35
Further, a leaf spring locking projection 44 for locking the return leaf spring 50 is provided outside the front end of the long side. The magnet 35 is housed and fixed in the magnet housing 47.

(5): Description of the Holder 30 The holder 30 is a holder made of a heat-resistant material of a bottomed cylindrical body having an open end, and a hole for inserting the armature 32 into a part of the bottom. 38 (through hole) is provided, and at the end of the hole 38, a semi-cylindrical convex portion 51 serving as a fulcrum (movable fulcrum) for the movement of the armature is provided. A return leaf spring 50 is provided so as to extend downward from the bottom of the holder 30.

The tip of the return leaf spring 50 is locked by the leaf spring locking projection 44 of the armature 32.
It has a function of pressing to the 0 side (returning the armature 32 to the return position). A claw (not shown) for supporting the reed switch holder 39 is provided below the holder 30, and the reed switch holder 39 is configured to be attached to the claw.

(6) Description of Reed Switch Holder 39 The reed switch holder 39 is made of a heat-resistant material such as ceramics or steatite, and has a recess formed therein for accommodating the reed switch 20 and the yoke 42. It is a thing. This reed switch holder 39
When the reed switch 20 and the yoke 42 are stored in the recess, the yoke 42 is disposed horizontally, and the reed switch 20 is disposed vertically with the ends inserted into the yoke 42.

The reed switch holder 39 holding the reed switch 20 and the yoke 42 is attached and fixed to a claw provided below the holder 30. The reed switch 20 is vertically stored in the reed switch holder 39 so that the tempura oil
Can be reduced in outer diameter.

(7): Description of Reed Switch 20 The reed switch 20 is inserted in the middle of a circuit connecting the thermocouple 5 and the coil 18 of the solenoid valve 10 and is used as a switch for turning on / off the circuit. It is. In this case, since the electromotive force of the thermocouple 5 is small, a reed switch 20 having as small a contact resistance as possible is used.

The reed switch 20 is driven by a magnetic flux from the magnet 35. In this case, FIG.
Has the ON region shown in FIG. That is, as shown in FIG. 4E, when a driving magnet Mg is placed around the reed switch 20 and the magnet Mg is moved in the illustrated X direction, Y direction, and −Y direction, the ON region ( O
N), a hold region (HOLD), and an off region.

In this case, the reed switch 20 is turned on in the illustrated ON area. Thus, the change in the position of the magnet Mg with respect to the reed switch 20 causes
The reed switch 20 can be turned on / off by changing the magnetic flux from the magnet Mg.

(8): Description of coil spring 31 The coil spring 31 has a cylindrical shaft 28
The holder 30 is placed on the flange-shaped spring receiver 29 provided on the upper side, and the holder 30 is placed on the upper side. That is, the coil spring 31 is inserted between the holder 30 and the cylindrical shaft 28, and constantly pushes the main body case 26 upward (in the direction of the pan 1). The tip (upper side of cap 25) of pan 1
For contacting the bottom of the

(9): Description of the cylindrical shaft 28 The cylindrical shaft 28 is attached to the main body case 26 and for attaching the tempura oil overheat prevention sensor 17 to the gas appliance, and is formed in a hollow cylindrical shape. I have. The cylindrical shaft 28 is provided with a flange-shaped spring receiver 29, and is attached to the main body case 26 using the spring receiver 29, and a portion protruding outside from the main case 26 is attached to a gas appliance. Have been. Further, a lead wire from the reed switch 20 can be drawn through the inside (inside of the hollow portion) of the cylindrical shaft 28.

(10) Description of the tube 40 The tube 40 is for protecting the lead wire drawn from the reed switch 20.

§3: Description of Method of Assembling Tempura Oil Overheat Prevention Sensor An example of the method of assembling the tempura oil overheat prevention sensor 17 having the above configuration will be described below.

When assembling the tempura oil overheat prevention sensor 17, each part is manufactured in advance, and the tempura oil overheat prevention sensor 17 is assembled using the parts. In this case, the magnet 35 is housed and fixed in the magnet housing 47 of the armature 32. The magnet 35 has, for example, an N pole (or S pole) on the upper side and an S pole (or N pole) on the lower side.
Pole).

The reed switch holder 39 houses the reed switch 20 and the yoke 42, and one of the lead wires drawn from the reed switch 20 is covered with a tube 40. The other lead wire is stored in the tube 41 together.

Then, the armature 32 is inserted into the hole 38 of the holder 30 (inserted with the short side up and the long side down), and the movable center of the armature 32 (the inside of the bent portion) is inserted into the hole 38. And is movably supported on the convex portion 51. A reed switch holder 3 is provided on the claw provided on the lower side of the holder 30.
At the same time, the distal end of the return leaf spring 50 fixed to the holder 30 is placed and locked on the leaf spring locking projection 44 provided on the armature 32. (Particularly, see FIG. 4B and FIG. C).

The components assembled in this manner are housed in the main body case 26. First, the cylindrical shaft 2 is inserted through the opening at one end of the large diameter portion 26A constituting the main body case 26.
8, the spring receiver 29 of the cylindrical shaft 28 is locked on the step 36 of the main body case 26 (the spring receiver 29 of the cylindrical shaft 28 is naturally dropped on the step 36 of the main body case 26 and Catch).

Next, the coil spring 31 is inserted through the opening of the large diameter portion 26A of the main body case 26, and is placed on the spring receiver 29 of the cylindrical shaft 28. Thereafter, the reed switch holder 39 accommodating the reed switch 20 and the holder 30 to which the armature 32 is attached are inserted through the opening of the main body case 26. In this case, the bottom portion of the holder 30 is placed on the coil spring 31, components such as the reed switch holder 39 are housed in the coil spring 31, and the lead from the reed switch 20 is passed through the hollow portion of the cylindrical shaft 28 to the outside. Withdraw to

Next, the bimetal 15 is placed on the open end of the holder 30, and a cap 25 is placed over the bimetal 15 and fixed, thereby completing the tempura oil overheat prevention sensor 17. In this manner, correct positioning can be achieved simply by inserting the cylindrical shaft 28 into the main body case 26 and placing each component thereon, and the tempura oil overheat prevention sensor 17 can be easily assembled.

§4: Description of operation of tempura oil overheat prevention sensor—see FIG. 5 FIG. 5 is an operation explanatory diagram of the tempura oil overheat prevention sensor.
The figure is a state 1 (reed switch on), the figure B is an explanatory view of the state 1, the figure C is a state 2 (reed switch off), and the figure D is an explanatory view of the state 2. Hereinafter, the operation of the tempura oil overheat prevention sensor 17 will be described with reference to FIGS.

The tempura oil overheat prevention sensor 17 operates as follows while being attached to the gas appliance. At the time of normal cooking, cooking is performed by putting oil 2 in the pot 1, and in this state, as shown in FIG. 5A, the bimetal 15 is in a convex state (operating temperature of the bimetal 15> Temperature T at the bottom of pan 1). At this time, the armature 32 is not driven by the bimetal 15, and a gap G of a certain length is provided between the bimetal 15 and the convex portion 37 of the armature 32.
Are formed.

For this reason, the end P of the long side of the armature 32 is pressed against the end of the yoke 42 by the return leaf spring 50 and returns to the return position.
Is in contact with the yoke 42 and no gap is formed between them. Therefore, the magnet 35
N pole → magnetic part 45 of armature 32 → reed switch 20 → yoke 42 → magnetic part 4 of armature 32
5 → The magnetic flux passes through the path of the S pole of the magnet 35, and the reed switch 20 is turned on (see FIGS. 5A and 5B).

Thereafter, when the temperature of the oil 2 rises and the bottom of the pot 1 reaches a predetermined temperature or higher (operating temperature of the bimetal 15 <temperature T of the bottom of the pan 1), the bimetal 15 is instantaneously inverted. , And becomes convex downward (snap action operation). The projecting portion 37 provided on the armature 32 is pressed downward by the instantaneous force when the bimetal 15 is inverted.

When the convex portion 37 is pushed downward in this manner, the armature 32 moves on the convex portion 51 provided on the holder 30 as a movable fulcrum and moves against the return force of the return leaf spring 50, and its length is increased. The tip P of the side is separated from the yoke 42 (see FIGS. 5C and 5D). Then, a gap is formed between the tip P of the long side of the armature 32 and the yoke 42,
The magnetic flux supplied from the magnet 35 to the reed switch 20 is cut off to turn off the reed switch 20.
In this case, the magnetic flux from the magnet 35 is
Circulates only in the peripheral portion of, and is not supplied to the reed switch 20.

When the reed switch 20 is turned off in this way, the coil 18 of the solenoid valve 10 is in a non-excited state, and the gas supplied to the gas burner 3 is shut off by the solenoid valve 10. Therefore, the flame 4 of the gas burner 3 goes out,
The temperature of the oil 2 in the pan 1 drops to prevent a tempura oil fire. Thereafter, when the temperature of the oil 2 in the pan 1 drops to a predetermined value, the bimetal 15 returns to the original state (the state of being convex upward). Therefore, the armature 3 is returned by the return force of the return leaf spring 50.
2 returns to the original position shown in FIG.

§5: Description of Test Results for Bimetal As shown in FIG. 4, the bimetal 15 used for the tempura oil overheat prevention sensor has a polyimide resin film 22 coated on the entire surface. In this case, by covering the entire surface of the bimetal 15 with the resin film 22 of a polyimide resin having a thickness t of about 8 to 15 μm, gas resistance, salt water resistance and the like are improved, and the bimetal 15 is rusted or corroded. To prevent

As described above, the polyimide resin film 2
The thickness t of No. 2 is preferably in the range of t = 8 to 15 μm, but this point was confirmed by the following test. In this test, a polyimide resin film 22 covering the bimetal 15 was used.
T = 0 (no resin film), t = 8-15 μm,
Three types of bimetals 15 having t = 20 μm were prepared as samples, and the reversal time of the bimetals 15 was measured while keeping the temperature of each sample at 250 ° C.

As a result, when the thickness t of the polyimide resin resin film 22 is t = 8 to 15 μm, the inversion time Td of the bimetal 15 is Td = 11 seconds, when t = 0, Td = 9 seconds, and t = 2 seconds.
At 0 μm, Td was 20 seconds. As can be seen from the test results, the thickness t of the polyimide resin film 22 is t
= 8 to 15 µm, and the difference between the inversion time Td of the bimetal 15 when t = 0 (no resin film) was 2 seconds.

That is, compared to the case where the bimetal 15 is not coated with a polyimide resin, the thickness t = 8 to 1
The reversal time of the bimetal 15 in the case of coating with a 5 μm polyimide resin takes an extra two seconds, but this time difference only increases the reversal temperature of the bimetal 15 by 3 ° C. However, such a temperature difference is a value that is not a problem.

On the other hand, when the thickness t of the polyimide resin resin film 22 is t = 20 μm, the reversal time Td of the bimetal 15 is Td = 20 seconds, and when the resin film 22 is thicker, the heat conduction becomes poor. It turned out that the reversal time of the bimetal 15 became extremely long and was not practical. Therefore, as described above, it was confirmed that the thickness t of the resin film 22 of the polyimide resin is preferably in the range of t = 8 to 15 μm. Further, the thickness t is applied to the entire surface of the bimetal 15.
A test was conducted to confirm the effect of coating the resin film 22 with a polyimide resin having a thickness of 8 to 15 μm, and the following test results were obtained.

(1): Gas resistance test In this test, the thickness t = 8 to 1 was applied to the entire surface of the bimetal 15.
The test was performed by placing the bimetal 15 coated with the resin film 22 of 5 μm polyimide resin in a test gas atmosphere. In this case, SO ₂ (sulfurous acid) gas and H ₂ S (hydrogen sulfide) gas (both gases are 5 ppm,
(40 ° C., 72-78%), and after 48 hours, the surface of the bimetal 15 was observed. As a result, no rust or corrosion was found on the bimetal 15.

(2): Saltwater resistance test In this test, the thickness t = 8 to
The test was performed by placing the bimetal 15 coated with the resin film 22 of a 15 μm polyimide resin in a test salt spray apparatus. In this case, the surface of the bimetal 15 was observed after a lapse of 96 hours while maintaining a temperature of 35 ± 2 ° C. using a 5% -concentration brine as a test condition. As a result, no rust or corrosion was found on the bimetal 15.

§6: Other explanations (1): The thickness of the resin film 22 made of the polyimide resin coated on the bimetal 15 is t = 8 to 1 as described above.
A range of 5 μm is preferable, but a thickness outside the above range can be used. However, as the thickness t of the resin film 22 becomes smaller than the above range, the function as a protective film becomes weaker and the coating process becomes more difficult. In addition, as the thickness t of the resin film 22 becomes thicker than the above range,
The thermal conductivity and inversion characteristics of the bimetal deteriorate. Therefore,
It is preferable that the thickness t of the resin film 22 be controlled in the range of t = 8 to 15 μ.

(2) The bimetal 15 is applicable not only to the tempura oil overheat prevention sensor having the above-described structure but also to any bimetal type tempura oil overheat prevention sensor. That is, the present invention can be applied to any configuration of a tempura oil overheating prevention sensor using a bimetal as a thermal element.

[0070]

As described above, the present invention has the following effects. (1): The bimetal is covered with a resin film of a polyimide resin. The resin film of this polyimide resin is excellent in heat resistance, gas resistance, salt water resistance and the like, and functions as a protective film for preventing rust and corrosion of the bimetal. Therefore, even when the bimetal is exposed to gas, salt water vapor, or the like, the metal forming the bimetal is not affected. Therefore, rust and corrosion of the bimetal can be prevented.

(2): As described above, since the bimetal is covered with the resin film of the polyimide resin, the bimetal has improved gas resistance, salt water resistance, and the like. As a result, rust and corrosion of the bimetal can be prevented, and a longer product life and higher reliability can be realized.

(3): Since the bimetal is coated with the polyimide resin, the gas resistance and salt water resistance of the bimetal are improved. Therefore, rust and corrosion of the bimetal can be prevented without using a bimetal-type tempura oil overheat prevention sensor in a sealed structure.

(4): The bimetal was coated with a polyimide resin in order to prevent rust and corrosion of the bimetal. However, since this resin film has high flexibility, the hardness of the bimetal is reduced as in the case of metal plating. Is never higher.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is an explanatory diagram of a gas appliance according to an embodiment.

FIG. 3 is an exploded perspective view of the tempura oil overheating prevention sensor according to the embodiment.

FIG. 4 is an explanatory diagram of components according to the embodiment.

FIG. 5 is a diagram illustrating the operation of the tempura oil overheat prevention sensor according to the embodiment.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pot 2 Oil 3 Gas burner 4 Flame 15 Bimetal 17 Tempura oil overheat prevention sensor 18 Coil 20 Reed switch 22 Resin film 25 Cap 26 Main body case 28 Cylindrical shaft 29 Spring receiver 30 Holder 31 Coil spring 32 Armature 35 Magnet 36 Step 37 Part 38 Hole 39 Reed switch holder 40, 41 Tube 42 Yoke 44 Leaf spring locking convex part 45 Magnetic part 46 Non-magnetic part 47 Magnet storage part

Claims (1)

[Claims] 1. A gas appliance comprising: a thermocouple heated by combustion of gas by a gas burner to generate an electromotive force; and a gas on-off valve driven by the electromotive force of the thermocouple to open and close a gas supply path to the gas burner. When the temperature of the bottom of the cooking utensil reaches a predetermined constant temperature, a bimetal-type tempura oil overheat prevention sensor that cuts off the drive current of the gas on-off valve and stops gas supply. A cap that covers the body case and is in contact with the bottom of the cooking utensil and is heat-sensitive; a switch inserted into a drive circuit of the gas on-off valve in the body case; a bimetal disposed inside the cap; The switch driving means for driving the switch with the reversing force of the bimetal is housed, and the bimetal is covered with a resin film of polyimide resin. Bimetallic tempura oil overheat prevention sensor.