JPH07167433A - Self current-control type glow plug - Google Patents

Abstract

PURPOSE:To provide a self current control type glow plug capable of performing an automatic interruption of an electrical energization for a coil after a desired time elapses. CONSTITUTION:A ceramic pipe 2 is fixed to a hollow main body 1 having a connector 12 therein. Ceramic filler 6 and 7 are filled at a front end 15 of the pipe 2 and an end part 17 of the main body. The coil 3 has a heater coil part 4 contacted with an inner wall surface 20 of the front end part 15 and also has a control coil part 5 not contacted with the inner wall surface 20 at its intermediate part 16. A PTC member 10 connects the end part 8 of the coil 3 with a connector 13 of a connector 12. The PTC member 10 has its resistance rapidly increased at a temperature higher than its desired temperature so as to interrupt an electrical energization for the coil 3. The front end 15 having the heater coil 4 arranged thereat forms a heat generating part and the control coil part 5 may form a current control part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a self-current control type glow plug used in a diesel engine or the like.

[0002]

2. Description of the Related Art Heretofore, a glow plug has been used as a starting assist device for a diesel engine. For example, as shown in FIG. 6, the glow plug 40 has a heating part 37, and the heating part 37 is arranged in a combustion chamber 39 of a sub chamber formed in a cylinder head 38 of a diesel engine. The glow plug 40 is connected with a relay or switch 41 when the engine key 36 is turned on, and a large current from the battery 42 is input to the heating portion 37 of the glow plug 40, and the heating portion 37 is heated in a short time. The fuel comes into contact with the heating portion 37 and the fuel is ignited and burned.

A conventional glow plug is constructed by embedding a tungsten wire in a ceramic such as silicon nitride and sintering it in order to heat it rapidly. Tungsten wire has a resistance value of 0.1Ω at room temperature against a 12V power source.
And the current is then 120A. The temperature of the glow plug rises from room temperature to 900
At 0 ° C., the resistance value becomes 0.4Ω, and the current at that time is 30 A. In order to control this current, another resistor is required, and when a metal wire with a large temperature coefficient of resistance is connected in series to the above resistor, the glow plug heats and the resistance value increases, Further, the resistance of the current control resistor increases, and the resistance value becomes 1Ω and becomes stable, and the current at that time is 12A. That is, in the conventional glow plug used in the diesel engine, when the current is supplied from the 12V battery according to the instruction of the controller, it is initially 1
A current of 20 A flows, but as the temperature of the heater coil rises, the resistance value increases and becomes stable when the resistance value becomes 1Ω. Therefore, in order to stabilize the glow plug at a resistance value of 1 Ω, the current is controlled by a controller command so that the heater coil is maintained at 1 Ω.

A conventional glow plug has been developed which can be self-controlled so that the glow plug is adjusted to 1Ω without using a controller. Tungsten W
And nickel Ni have the characteristic that the resistance value Ω increases and increases as the temperature rises. Therefore, in the tungsten W wire and the nickel Ni wire, the resistance value Ω increases as the temperature rises, the current decreases, and the current value is limited. Therefore, the self-regulating glow plug is
A tungsten W wire is embedded in a ceramic such as Si ₃ N ₄ , and a nickel Ni wire coil is connected in series with the W wire. That is, in the self-regulating glow plug, a conductor having a small electric resistance value is arranged in the heating element portion of the heater coil, and a metal wire having a large electric resistance value of the Ni wire coil is connected to the upstream side of the conductor. It was made by. In such a self-regulating glow plug, the Ni coil is overheated by passing an electric current to increase the resistance value, and the electric current is reduced to control the heat generation amount of the heating element portion of the heater coil. .

Conventionally, self-current control type glow plugs are disclosed in Japanese Examined Patent Publication No. 4-34052 and Japanese Examined Patent Publication No. 60-194.
No. 04, JP-A-59-157423, JP-A-58-106326, and the like.

For example, in the self-regulating glow plug disclosed in Japanese Patent Publication No. 4-34052, a current control resistor is connected in series to the heating element in order to control the temperature of the heating element when the current is heated. The heating wire coil and the resistor coil are connected in series and embedded in the ceramic sintered body to form an integrated ceramic heater, and the heating wire has a temperature-resistance coefficient of 4 times or less. Such a tungsten W and rhenium Re alloy wire having a positive temperature coefficient of resistance are used, and the resistor is a wire material of pure W or pure molybdenum Mo.

In the sheath glow plug disclosed in Japanese Patent Publication No. 19404/1985, the heating element and the resistor of the winding are directly connected between the inner bottom of the heat-resistant bottomed metal tube and the center electrode. This is a self-regulating type sheath glow plug having the winding pitch of the resistor formed close to the central electrode side close to the electrode side fitting, and the portion close to the heating element side formed roughly.

[0008]

However, the conventional self-current control type glow plug has sufficient heat resistance, strength against heat shock, high temperature strength, etc. when used in a high temperature combustion chamber such as a heat shield engine. It was something I couldn't say. Further, in the self-control glow plug disclosed in the related art, a heating wire coil made of tungsten carbide wire and a resistor coil made of Ni wire coil are connected to each other, and both are made of materials having different resistance temperature coefficients. Or the heating element and the resistor of the winding are formed in different shapes, there is a problem that the Ni wire is disconnected due to overheating during use or deteriorates due to aging. The structure became complicated, and the cost and strength were not satisfactory.

With regard to the ceramic glow plug, a self current control type glow plug can be constructed by the resistance value extremely increasing in the upstream region of the current path of the heater coil. Normally, a glow plug has a saturation current of about 1Ω at a power supply voltage of 12 V and a temperature of about 900 ° C.
Is held in. In order to heat the glow plug instantaneously, about 0.1Ω is required at room temperature. Normal,
Since a heating wire, that is, a wire used as a heater coil has a temperature coefficient of resistance of about 4 × 10 ⁻³ , the current cannot be saturated at 900 ° C.

Further, the glow plug is arranged in the combustion chamber and is heated in a short time by supplying an electric current to assist the ignition and combustion of the fuel as a start-up assist device. However, in a diesel engine, the glow plug is heated above a certain temperature. The fuel can be sufficiently ignited and burned without the assistance of ignition.
Therefore, when the temperature in the combustion chamber rises above a certain temperature, it is necessary to stop the glow plug heating function by shutting off the current to the glow plug. With conventional glow plugs, the power to the glow plug is cut off. Need a current breaker. Therefore, the self-current control type glow plug as described above has been developed. However, the conventional self-current control type glow plug can reduce the current to the heater coil wire automatically even if it can automatically reduce the current to the heater coil wire. Since it does not have a function of cutting off the current to the heater coil wire, it requires a breaking device such as a timer to cut off the current to the heater coil wire.
Moreover, such a breaker requires a complicated mechanism such as changing the energization period depending on the engine condition.

Therefore, an object of the present invention is to solve the above-mentioned problems, and a coil arranged in a ceramic pipe is used as a heater coil section constituting a heat generating section and a control coil section constituting a current control section. The glow plug is configured as a self-current control type glow plug that secures an optimum amount of heat by adjusting the current flowing through the heat generating part and the current control part. PTC (Positive Tempe) that has the function of increasing
The structure of the PTC member is such that the current flowing through the coil is automatically cut off in response to the temperature rise due to the current cutoff function of the PTC member. It is an object of the present invention to provide a self-current control type glow plug having a structure that reduces the specific resistance by devising its structure.

[0012]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention provides a hollow main body in which a connector is arranged via an insulating member, a ceramic pipe attached to the hollow main body, and a front end portion of the pipe protruding from the hollow main body. A coil in which a heater coil portion and a control coil portion disposed inside the middle portion of the pipe are configured in series, and a resistance value is disposed in the hollow main body in series with the heater coil portion and at a predetermined temperature or higher. Having a PTC member that increases sharply and greatly reduces the current to the coil,
The PTC member has a plurality of PTs, one end of which is connected to the connector and the other end of which is connected to the coil terminals of the coil in parallel.
The present invention relates to a self-current control type glow plug which is composed of a C terminal.

Further, in this self-current control type glow plug, the coil terminals are metal disks which are spaced apart from each other on the connector, and the PTC terminals are PTC disks corresponding to the metal disks.

Alternatively, according to the present invention, a hollow main body in which a connector is arranged via an insulating member, a ceramic pipe attached to the hollow main body, and an inside of a front end portion of the pipe protruding from the hollow main body A coil in which a heater coil section disposed in the pipe and a control coil section disposed inside the intermediate portion of the pipe are configured in series, and the heater coil section is disposed in the hollow main body in series and at a predetermined temperature or higher. The PTC member has a resistance value that sharply increases to greatly reduce the current to the coil. One end of the PTC member is connected to the connector and the other end is connected to a coil terminal of the coil.
The present invention relates to a self-current control type glow plug which is composed of a TC disk. The PTC disk is a spiral member wound between the connector and the coil terminal.

In this self-current control type glow plug, the PTC is a BaTiO ₃ system sintered body or PbT.
It is composed of an iO ₃ system sintered body.

In the self-current control type glow plug, the coil is made of tungsten wire.

Further, in this self-current control type glow plug, the pipe is made of Si ₃ N ₄ having _high heat resistance, and the first ceramics filling body filled in the portion where the heater coil portion is located and The second ceramics filling body filled in the end portion of the pipe on the main body side to seal the middle portion of the pipe is made of Si ₃ N containing TiO _2.
It consists of _four .

[0018]

The self-current control type glow plug according to the present invention is constructed as described above and operates as follows. That is, in this self-current control type glow plug, a ceramic pipe is attached to a hollow main body in which a connector is disposed, and a heater coil portion disposed inside the pipe and an intermediate portion of the pipe are disposed. A coil having a control coil unit arranged in series is arranged in the pipe, and the connector and the coil are connected by a PTC member that cuts off the current flowing through the coil due to a sharp increase in resistance value at a predetermined temperature or higher. Moreover, since the PTC member is composed of a plurality of PTC terminals, one end of which is connected to the connector and the other end of which is connected in parallel to the coil terminal of the coil, the front end portion of the pipe in which the heater coil portion is arranged is arranged. Constitutes a heat generating portion, and an intermediate portion of the pipe in which the control coil portion is arranged constitutes a current control portion. In particular, since the connector and the coil are connected to each other by a plurality of PTC terminals having a large area and a small thickness that constitute the PTC member, the resistance of the PTC member can be reduced at low temperatures, and the PTC member can be reduced. The resistance value of the PTC member sharply increases as the temperature of the region where is located increases, and the current supplied to the coil is automatically cut off.

In this self-current control type glow plug, when a current is supplied to the coil from the battery, the heat generated in the heat generating portion in which the heater coil portion is positioned heats the pipe and radiates it to the outside. On the other hand, the heat generated in the control coil section is shielded and the temperature rises, and the current flowing through the control coil section is suppressed with the temperature rise, thus forming a current control section. Therefore, when the temperature of the control coil portion becomes high, its resistance value becomes large, the current flowing through the coil, that is, the tungsten wire becomes small, and the amount of heat generated from the ceramic pipe is self-controlled and controlled to an optimum value. It will be.

In particular, when the coil is energized, the electrical resistance of the PTC member must be small, but since the PTC members are connected in parallel at the plurality of PTC terminals, the PTC member is connected at a low temperature. The resistance value of the member as a whole becomes small. That is, the PTC member has a very large resistivity (coefficient) k, and is made of a general metal of 1
× 10 ^- a is whereas ^{5 Ω} · cm, a 1 [Omega · cm. If such a PTC member is directly connected to a metal wire, an extremely large area is required. The resistance value of an object is
Usually, it is represented by R = k · L / A. Where L is the length,
A represents the area. When calculated from this equation, the PTC member to L / A 10 ^- to be ^five times, not a same resistance value and metal. Therefore, the method for reducing the thickness of the PTC member to be energized and increasing the area is a condition for establishing this self-current control type glow plug. On the other hand, if the resistors are connected in parallel, the overall resistance value can be reduced. For example, when n PTC terminals are used,
Let R be the total resistance and R ₁ , R ₂ ,
If R _{3 to} R _n , then 1 / R = 1 / R ₁ + 1 / R
₂ + R is ₃ ~ + 1 / R _n. If the resistance values of the PTC terminals are the same resistance value R ₁ , 1 / R = n
× 1 / R ₁ . Therefore, R = R ₁ / n, and the resistance value of the PTC member becomes small as a whole.

Next, when the temperature of the region of the PTC member further rises to a predetermined temperature or higher, the resistance value of the PTC member sharply rises. In this case, if the coil terminal that comes into contact with the PTC terminal of the PTC member is made of a metal disk, the metal disk uniformly generates heat when energized, the entire PTC member is heated, and the resistance of the PTC member is increased. The value rises sharply. When the resistance value of the PTC member increases, the current supplied to the coil is automatically cut off, and the function of the self-current control glow plug is stopped.

Alternatively, the PTC member has one end connected to the connector and the other end connected to the coil terminal of the coil.
When it is composed of a C disk, the resistance R of the PTC member is inversely proportional to the area A as described above. That is, R = k · L / A. Also, the PT
Even when the C disk is composed of a spiral member wound between the connector and the coil terminal, the area can be increased and the resistance can be reduced.

Further, since the control coil portion arranged in the middle portion of the pipe is covered with a heat insulating material and is shielded from heat to the pipe, the control coil portion is surely shielded from heat. Therefore, a highly reliable current control unit can be configured. Further, since the ceramics forming the first ceramics filling body and the second ceramics filling body are made of Si ₃ N ₄ containing TiO ₂ , the thermal conductivity is good, and the pipe is in a sealed state. Can be well configured.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a self-current control type glow plug according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an embodiment of the self-current control type glow plug according to the present invention, and FIG. 2 is a graph showing the relationship between the temperature and the resistance value of the PTC member incorporated in the self-current control type glow plug of FIG. 3 and 4 are enlarged sectional views showing an embodiment of the PTC member incorporated in the self-current control type glow plug of FIG.

This self-current control type glow plug is mainly composed of a hollow body 1 in which a terminal or connector 12 is arranged in a hollow portion 21 with an insulator 19 such as an insulating bush interposed.
It is composed of a ceramic pipe 2, a coil 3 made of tungsten wire or the like, a PTC member 10 connecting the coil 3 and the connector 12, and ceramic filling bodies 6 and 7 filled at both ends of the pipe 2. The hollow main body 1 is made of a metal such as a heat-resistant alloy, and has a screw 22 formed on the outer peripheral surface for attachment to other parts. A nut 18 for positioning and fixing is screwed into the connector 12,
Are positioned and fixed to the hollow body 1. In order to connect the ceramic pipe 2 to the hollow main body 1, the outer peripheral surface 23 of the ceramic pipe 2 is metallized to form the main body 1.
If the inner peripheral surface 24 is fitted and joined, the pipe 2 and the hollow main body 1 can be joined very firmly. Further, the front end portion 15 which constitutes the heat generating portion of the ceramic pipe 2 has the hollow main body 1
Is arranged so as to project from the end 25 of the. Coil 3
Has one end 8 connected to one end of the PTC member 10,
The other end of the PTC member 10 is connected to the connector 12 by the connector unit 1.
3 are connected. The other end 9 of the coil 3 is the main body 1
Is electrically connected to the ground state.

In this self-current control type glow plug, the hollow main body 1 has a conductor 21 having a connector 12 and a hollow portion 21.
The ceramic pipe 2 forming the tip portion, that is, the front end portion 15 that forms the heat generating portion is fixed to the main body 1 in a protruding state from the main body 1. A first ceramics filling body 6 and a second ceramics filling body 7 are provided at both ends of the pipe 2.
It is sealed with. The front end portion 15 of the pipe 2 is configured in a closed state, and the intermediate portion 16 of the pipe 2 has a hollow portion 26 formed therein. In the hollow portion 26 of the pipe 2, a double pipe made of a heat insulating material 11 made of ceramic fiber such as SiC is arranged to cover the control coil portion 5 of the coil 3 from the inner and outer surfaces. Therefore, the control coil unit 5 of the coil 3 is
The pipe 2 is shielded from heat. Hollow part 2 of pipe 2
6 is a vacuum state or a state in which N ₂ gas is enclosed,
The coil 3 is structured to prevent oxidation. Further, the electrode-side end 17 of the pipe 2 is sealed with the second ceramics filling body 7.

In this self-current control type glow plug, the coil 3 is made of a tungsten wire or the like, and the heater coil portion 4 and the pipe 2 which are arranged in contact with the inner wall surface 20 inside the front end portion 15 of the pipe 2 are provided. The control coil section 5 arranged in a non-contact state on the inner wall surface 20 inside the intermediate section 16.
It has and. The tip portion 15 of the pipe 2 is filled with the first ceramics filling body 6 having good thermal conductivity.
The heater coil portion 4 is pressed against the inner wall surface 20 of the pipe 2 by the ceramics filling body 6 in a contact state. Further, the second ceramics filling body 7 is closely attached to the inner wall surface 20 of the pipe 2 at the body-side end portion 17 of the pipe 2,
The coil 3 is filled in close contact with the outer peripheral surfaces of the ends 8 and 9 and seals the hollow portion 26 of the intermediate portion 16 of the pipe 2. A connector portion 13 is provided at the end portion of the connector 12, and an annular coil terminal 28 is provided at the end portion 8 of the coil 3.
Is provided. The coil terminals 28 are arranged on the inner wall surface of the hollow main body 1 with an insulating material 29 interposed therebetween. The coil terminals 28 extend radially inward from the inner wall surface of the coil terminal 28 and are spaced apart in the longitudinal direction. It has a plurality of PTC terminals 27.

This self-current control type glow plug is particularly characterized by the PTC member 10 for connecting the connector portion 13 of the connector 12 and the end portion 8 of the coil 3 to the hollow portion 21 of the hollow body 1. is there. The PTC member 10 is made of a material whose electric resistance value exponentially and rapidly increases at a certain temperature, and the resistance value abruptly increases at a predetermined temperature or higher and has a function of blocking a current flowing through the coil 3 at a positive temperature. It is a coefficient member (that is, a temperature rising current interruption member). The PTC member 10 is made of a semiconductor-made BaTiO ₃ system sintered body (or Pb).
TiO ₃ based sintered body). PTC member 1
0 is composed of a plurality of PTC terminals 27, one end of which is connected to the coil terminal 28 of the coil 3 and the other end of which is connected to the connector portion 13 in parallel. The metal discs 14 are a plurality of disc members that are longitudinally separated by PTC spacers 35 on the connector portion 13, and the coil terminals 28 have a plurality of PTC terminals 27 corresponding to the respective metal discs 14. . If the metal discs 14 are separated by the PTC spacers 35, the metal discs 14 are separated at low temperatures.
Current flows through the PTC spacer 35 when it gets hot.
Therefore, the current flow is reduced, the conduction between the metal disks 14 is cut off, and the power supply from the connector portion 13 to the coil terminal 28 is substantially cut off. B
As shown in FIG. 2, the PTC terminal 27 of the aTiO ₃ -based sintered body has a PTC terminal 27 whose resistance value increases to 10 ⁴ Ω to 10 ⁵ Ω when the temperature rises to 120 ° C. to 130 ° C., for example. It has a function, that is, a dielectric function. That is,
When the PTC terminal 27 is heated to 120 ° C., its resistance value becomes 10 ⁴ Ω. If there are 10 PTC terminals 27 forming the PTC member 10, since the PTC terminals 27 are connected in parallel, the overall resistance value of the PTC member 10 is 10 ³ Ω, and no current flows through the PTC member 10. It almost does not flow.

Therefore, when an electric current is applied to the coil 3,
When the heat generated in the metal disk 14 connected to the heater coil portion 4, the control coil portion 5 and the connector portion 13 of the coil 3 or the combustion heat of the combustion chamber is transferred to the PTC terminal 14, after a predetermined time has passed, , PTC terminal 14 is 120
It is heated to about ℃. When the PTC terminal 14 is heated to 120 ° C. or higher, the resistance value of the PTC terminal 14 sharply increases and the current supplied to the coil 3 is cut off. The time for which the PTC terminal 14 is heated to 120 ° C. or higher can be arbitrarily set according to various conditions such as the design and structure of the combustion chamber, cylinder head, cooling jacket, self-current control glow plug, etc. When the shape glow plug is applied as a start assist device for a diesel engine, the period from the start of energization to the cutoff state is about 3 to 5 minutes, and in that case, the PTC member 10 supplies the current to the coil 3. The feed can be shut off after 3-5 minutes.

In this self-current control type glow plug, the ceramics forming the pipe 2 is Si ₃ N ₄
Further, the ceramics forming the first ceramics filling body 6 and the second ceramics filling body 7 are Si ₃ N
₄ and TiO _2, and in some cases TiN
Includes ₂ . Further, the coil 3 includes the first coil portion 4
Is formed to have a large diameter, and the control coil portion 5 is formed to have a small diameter, and is made of one continuous tungsten wire. The heater coil portion 4 of the coil 3 can provide sufficient heat to heat the front end portion 15, and the temperature of the front end portion 15 is immediately raised in a short time to form a heat generating portion.
The control coil unit 5 does not radiate heat, and the resistance value increases as the temperature rises to form a current control unit that controls the current.

In the self-current control type glow plug, the pipe 2 is preferably made of heat-resistant and high-strength Si ₃ N ₄ ceramics. Further, the ceramic fillers 6 and 7 are made of Si ₃ N ₄ which is rich in heat resistance, high temperature and high strength.
And preferably 10% of TiO ₂ is added to Si ₃ N _4.
% Ceramics, and in some cases also TiN ₂ containing ceramics. TiO ₂ , T
If it is made of Si ₃ N ₄ containing iN ₂ , the thermal conductivity becomes good, and at the same time, it becomes non-shrinking due to the sintering, so that the pipe 2 can be sealed. Hollow part 2 of pipe 2
When 6 is vacuum-sealed or N ₂ gas is not sealed, it is necessary to coat the tungsten wire with SiC or WC in order to prevent the tungsten wire constituting the coil 3 from being oxidized. In this case, the tungsten wire can be prevented from being oxidized, the corrosion resistance can be improved, and the durability of the tungsten wire can be improved.

Since this self-current control type glow plug is constructed as described above, it operates as follows. That is, in this ceramic glow plug, the current supplied from the battery is the connector 12 and the annular connector portion 13.
And the PTC member 10 to supply the coil 3. The control coil portion 5 of the coil 3 is arranged in the hollow portion 26 in a heat-shielding state, and the heater coil portion 4 includes the inner wall surface 2 of the pipe 2.
Since it is in contact with 0, the front end portion 15 of the pipe 2 is heated by the heat generation of the heater coil portion 4 and becomes a heat generating portion. Therefore, the front end portion 15 of the pipe 2 can be disposed in the combustion chamber to function as a start assist device. Here, the heat generated in the heater coil portion 4 is radiated through the pipe 2, but the heat of the control coil portion 5 is not radiated, and the control coil portion 5 becomes extremely hot as compared with the heater coil portion 4. .
When the temperature of the control coil portion 5 becomes high, the control coil portion 5 functions as a current control line, its resistance increases and increases, the current flowing through the coil 3 is suppressed and decreases, and the heat generation of the front end portion 15 occurs. The quantity is self-controlled. Further, if the temperature of the control coil portion 5 is lowered, the electric current flows through the coil 3 again, and the heater coil portion 4 heats the front end portion 15.
Therefore, the heat generating portion of the front end portion 15 is always maintained at the optimum heat generation amount, and functions well as a start assist in the combustion chamber.

In this self-current control type glow plug, since the pipe 2 in which the heater coil portion 4 is inscribed is exposed to the outside of the combustion chamber or the like, heat is dissipated from the pipe 2, for example,
The temperature of the front end portion 15 is maintained at 900 ° C. and the resistance value of the heater coil portion 4 becomes 0.4Ω. However, since the control coil portion 5 is located inside the sealed hollow portion 26, heat is shielded. For example, the temperature of the control coil unit 5 becomes 1800 ° C. and the resistance value of the control coil unit 5 becomes 0.6Ω. Therefore, in this self-current control type glow plug, the sum of the resistance values of the heater coil section 4 and the control coil section 5 becomes 1Ω, and the stable state is achieved.

When the heater coil section 4 and the control coil section 5 continue to generate heat in a stable state, the combustion chamber repeats favorable combustion, and when the engine starts to operate smoothly, the combustion heat of the combustion chamber, etc. The heat is transferred to the PTC member 10, the metal disk 14 forming the connector portion 13 generates heat, and the temperature of the PTC terminal 27 rises to 120 ° C. to 130 ° C., for example. When the temperature of the PTC member 10 rises to 120 ° C. to 130 ° C., the resistance value of each PTC terminal 27 of the PTC member 10 sharply rises, for example, 10 ⁴ Ω to 10 ⁵ Ω. If the resistance value of each PTC terminal 27 of the PTC member 10 rises to 10 ⁴ Ω to 10 ⁵ Ω, the PTC member 1
0 itself is in the same state as when the current is cut off, and the power supply to the coil 3 is cut off.

Next, another embodiment of the self-current control type glow plug according to the present invention will be described with reference to FIG. This embodiment has the same structure as the above embodiment except that the PTC member is different. 4 is shown in FIG.
FIG. 6 is an enlarged cross-sectional view showing another example of the PTC member incorporated in the self-current control glow plug of FIG. PT of this embodiment
The C member 10 has the PTC terminal formed on the annular ring 31 so as to be connected to the inner wall surface of the annular member 30 of the coil terminal 28 via the conductive ring 34. Also, the annular ring 3
1 and the coil terminal 28 are isolated from each other by an insulating member 33. Furthermore, the coil terminal 28 is connected to the end portion 8 of the coil 3, and the annular ring 31 is connected to the connector portion 13. Therefore, since the PTC member 10 has the PTC terminal formed on the annular ring 31, the PTC member 10 can have a large area. Therefore, PT
The C member 10 has a low resistance value at a low temperature, for example, 12
When the temperature is higher than 0 ° C., the resistance value becomes extremely large, so that the power supply to the coil 3 is cut off.

Next, another embodiment of the self-current control type glow plug according to the present invention will be described with reference to FIG. This embodiment has the same structure as the above embodiment except that the PTC member is different. Figure 5
Is P incorporated in the self-current control type glow plug of FIG.
It is an expanded sectional view showing another example of a TC member. The PTC member 10 of this embodiment is the annular member 3 of the coil terminal 28.
The PTC terminal is formed in a spiral spirally wound circular body 32 so as to be in contact with the inner wall surface of the PTC member 0 to increase the area of the PTC member 10. The function is the same as that of the self-current control type glow plug shown in FIG.

Therefore, when this self-current control type glow plug is used as a start assist device for a diesel engine, the coil 3 can be automatically de-energized in response to combustion of the engine, and the self-current control can be performed. The unnecessary heating of the glow plug is no longer continued, and the power of the battery is not wasted.

[0038]

The self-current control type glow plug according to the present invention is constructed as described above and has the following effects. That is, this self-current control type glow plug is
A ceramic pipe is attached to the hollow main body, a coil is arranged in the sealed pipe, and the coil is composed of a heater coil portion inside the pipe and a control coil portion inside the middle portion of the pipe, A plurality of PTC terminals in which the coil and the connector are connected by a PTC member whose resistance value rapidly increases at a predetermined temperature or higher, and the PTC member is connected in parallel at one end to the connector and at the other end to the coil terminal of the coil. Since the PTC member is heated to a predetermined temperature or higher, the current flowing through the coil can be automatically cut off, and the tip end portion of the pipe in which the heater coil portion is arranged can generate a heat generating portion. The intermediate portion of the pipe configured to arrange the control coil portion constitutes a current control portion, and the arrangement can be stabilized at an optimum temperature.

That is, when an electric current is passed through the coil, the heater coil section constitutes a heat generating section, the control coil section constitutes a current control section, and if the control coil section becomes high in temperature,
The resistance value increases, the current flowing through the coil decreases, and the amount of heat generated from the ceramic pipe is self-controlled and controlled to an optimum value. Further, when the engine is operated smoothly and the heat of combustion from the combustion chamber or the heat generated by the coil is transferred to the PTC member, the temperature of the PTC member rises above a predetermined temperature and the resistance value of the PTC member increases. It increases rapidly and cuts off the current to the coil. Therefore, when this self-current control type glow plug is applied as a start assist device for a diesel engine, a timer or the like for shutting off the self-current control type glow plug is not required, and power such as a battery is wasted. Nothing.

In this self-current control type glow plug, the PTC member is formed by connecting in parallel a plurality of PTC terminals made of a semiconductor-made BaTiO ₃ system sintered body or PbTiO ₃ system sintered body. The resistance of the PTC member at a low temperature can be reduced as a whole, and the current flow through the PTC member can be made smooth while the temperature rises to a predetermined temperature. That is, BaTi forming the PTC member
The PTC terminal of the O ₃ system sintered body has, for example, 120 ° C.
When the temperature rises to 130 ° C, the resistance value suddenly increases from 10 ⁴ Ω to
The PTC member is increased to 10 ⁵ Ω.
If the PTC terminal is made of one sheet, the entire PTC member has a resistance of 10 ³ Ω to 10 ⁴ Ω, and functions as a dielectric.

Further, the self-current control type glow plug may be configured to have a shape in which the area of the PTC member is increased. At that time, as in the case described above, the resistance of the PTC member at low temperatures can be reduced, and the current flow through the PTC member during the rise to a predetermined temperature can be made smooth. When the temperature of the PTC member rises, the current to the coil is cut off as described above.

The coil may be made of tungsten wire. The control coil part arranged in the middle part of the pipe is covered with a heat insulating material and is shielded from heat to the pipe, so that current control can be appropriately performed. Further, the ceramics forming the pipe is Si
Since it is ₃ N _4, it is rich in heat resistance and oxidation resistance, and the pipe itself can be manufactured with high strength. Also, the first
Since the ceramics constituting the ceramics filling body and the second ceramics filling body are made of Si ₃ N ₄ containing TiO ₂ , there is no firing shrinkage, thermal conductivity can be improved, and the inside of the pipe can be satisfactorily improved. Can be sealed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of a self-current control type glow plug according to the present invention.

FIG. 2 is a graph showing a relationship between a temperature and a resistance value of a PTC member incorporated in the self-current control type glow plug of FIG.

FIG. 3 is an enlarged sectional view showing an embodiment of a PTC member incorporated in the self-current control type glow plug of FIG.

FIG. 4 is an enlarged cross-sectional view showing another embodiment of the PTC member incorporated in the self-current control type glow plug of FIG.

FIG. 5 is an enlarged cross-sectional view showing still another embodiment of the PTC member incorporated in the self-current control glow plug of FIG.

FIG. 6 is an explanatory view showing a state in which a glow plug is arranged in a combustion chamber of a conventional diesel engine.

[Explanation of symbols]

1 Hollow Main Body 2 Ceramic Pipe 3 Coil 4 Heater Coil 5 Control Coil 6 First Ceramics Filler 7 Second Ceramics Filler 8 Coil End 9 Coil End 10, 35 PTC Member 11 Thermal Insulation 12 Connector 13 Connector Part 14 Metal Disk 15 Tip of Pipe 16 Middle Part of Pipe 17 Body End of Pipe 19 Insulator 20 Inner Wall of Pipe 21 Hollow Body Hollow Body 27 PTC Terminal of BaTiO ₃ Sintered Body 28 Coil Terminal 29 Insulation material 30 Annular member 31 Annular ring 32 Circular spiral body

Claims (7)

[Claims] 1. A hollow main body in which a connector is arranged via an insulating member, a ceramic pipe attached to the hollow main body, and a front end of the pipe protruding from the hollow main body. A coil in which a heater coil portion and a control coil portion disposed inside the middle portion of the pipe are configured in series, and the resistance value is rapidly increased at a predetermined temperature or higher and disposed in the hollow body in series with the heater coil portion. And a PTC member that greatly reduces the current to the coil, and the PTC member is composed of a plurality of PTC terminals whose one end is connected in parallel to the connector and the other end is connected in parallel to the coil terminal of the coil. A self-current control type glow plug characterized by being used. 2. The coil terminals are metal disks spaced apart from each other on the connector, and the PTC terminals are PTC disks corresponding to the metal disks, respectively. Self-current control type glow plug. 3. A hollow main body provided with a connector via an insulating member, a ceramic pipe attached to the hollow main body, and a front end portion of the pipe protruding from the hollow main body. A coil in which a heater coil portion and a control coil portion disposed inside the middle portion of the pipe are configured in series, and the resistance value is rapidly increased at a predetermined temperature or higher and disposed in the hollow body in series with the heater coil portion. And a PTC member that greatly increases the current to the coil, and the PTC member is composed of a PTC disk having one end connected to the connector and the other end connected to the coil terminal of the coil. A characteristic self-current control type glow plug. 4. The self-current control glow plug according to claim 3, wherein the PTC disk is a spiral member wound between the connector and the coil terminal. 5. The self-current control glow plug according to claim 1, wherein the PTC is composed of a BaTiO ₃ system sintered body or a PbTiO ₃ system sintered body. 6. The self current control type glow plug according to claim 1, wherein the coil is made of a tungsten wire. 7. The pipe is made of Si ₃ N _{4 having high} heat resistance.
The first ceramics filling body filled in the portion where the heater coil is located and the second ceramics filling body filled in the end portion on the main body side of the pipe for sealing the middle portion of the pipe are S containing TiO ₂
i ₃ N _{4 is} formed.
7. A self-current control type glow plug according to any one of items 6 to 6.