JPH0791356A - Ignition system circuit breaker - Google Patents

Abstract

PURPOSE:To break any current-energization in an ignition system circuit in making the resistance of a variable resistive element go up suddenly in time of abnormal temperature rise in an engine room by connecting an ignition switch and an ignition coil together via the variable resistive element installed in and around an engine. CONSTITUTION:An ignition system circuit K ignites a mixture gaseous body between air and combustible gas to k:e fed to an engine, and it is composed of an ignition switch SW installed in a driver's seat, an ignition coil 1 with a primary side coil 3 to be turned on or off by an igniter 2 and a secondary side coil 4 to be opposed to the former, and a park plug (d) to be connected to the secondary side coil 4 via a distributor 6. In this case, the ignition switch SW and the ignition coil 1 are connected to each other via a variable resistive element installed in and around the engine. In this constitution, at the time of an abnormal temperature rise in an engine room, resistance in this variable resistive element is made to go up suddenly and thereby any current-energization for the ignition system circuit K is cut off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention ignites a mixed gas of an air supplied to an engine and a combustible gas when the temperature in the engine room becomes high by, for example, driving an engine of an automobile. Turn off the power to the ignition system circuit,
The present invention relates to an ignition system circuit breaker for protection.

[0002]

2. Description of the Related Art Conventionally, for example, FIG.
In addition, the ignition system circuit for igniting and exploding the mixed gas of the air supplied to the engine E and the combustible gas has the one shown in FIG. In FIG. 8, an engine E includes a cylinder c that accommodates a piston a so that the piston a can be moved up and down, a cylinder b to which a mixed gas b of air and a combustible gas such as hydrocarbon is supplied, and an ignition plug d that ignites and explodes the combustible gas. It is composed of an ignition system circuit K'and a crankcase f provided below the cylinder c and provided with a crank to which the piston rod e of the piston a is connected.

When a certain proportion of the mixed gas b is supplied into the cylinder c, the mixed gas b is ignited by the ignition plug d and explodes, so that the piston a descends in the cylinder c by its explosive force. Then, a crank (not shown) is driven via a piston rod e that follows the piston a and descends. At this time, the piston a having the same structure as that shown in FIG. 8 in the exhausted state is lifted by the crank in the cylinder c and exhausted. In this way, the intake and exhaust in the cylinder c are alternately repeated to move the crank and obtain a driving force.

The mixed gas b supplied into the cylinder c
An ignition system circuit K'for igniting and exploding
As shown in FIG. 1, an ignition switch SW, a primary side coil 3 that is turned on and off by the igniter 2, and a primary side coil 3 that is electromagnetically induced by turning on and off the primary side coil 3 are provided. Ignition coil 1 having a secondary coil 4 connected thereto and connected to the ignition switch SW via a fuse 5'as a protection means, and ignition connected to the secondary coil 4 via a distributor 6. Plug d
Formed from. A power source 7 is connected to the ignition switch SW.

When the ignition switch SW is turned on during operation and the primary coil 3 of the ignition coil 1 is turned on / off by the igniter 2, a high voltage is generated in the secondary coil 4 by electromagnetic induction, and the ignition plug is turned on. gas mixture b supplied into the cylinder c by d
Was ignited and exploded.

[0006]

Recently, a fire of a vehicle has become a problem. One of the causes is a high temperature and high pressure when the engine E having the structure shown in FIG. 8 is left idle for a long time. Blow-by gas flows back from engine E to the outside,
It is possible to raise the temperature inside the engine room EG.

This long-running empty state can easily occur by, for example, taking a nap while depressing the accelerator pedal without stopping the engine E of the automobile in a parking area or the like, but the generation of blow-by gas is Ignition of the mixed gas b by the spark plug d occurs when the unburned mixed gas b leaks into the crankcase f through the gap between the inner wall of the cylinder c and the piston a during the explosion process.

Since the mixed gas b contains a combustible gas such as a hydrocarbon, the primary ports g ₁ and g ' ₁ are connected to the upper part and the intermediate part of the cylinder c, respectively, and they are connected to each other in common. The mixed gas b was circulated back into the cylinder c through the circulation conduits g, g ′ and the conduit g ″ in which the secondary port g ₂ was connected to the intake side above the cylinder c.

However, the blow-by gas gradually accumulates in the engine E by overflowing, and overflows from the intake side, and the high-temperature and high-pressure gas flows back to the outside of the engine E. At this time, the temperature of the engine E reaches 200 ° C. or higher, but even if such a dangerous temperature is reached, the fuse 5 ′ is immediately blown and the ignition system circuit K ′ is not turned off. There was a risk of becoming.

Therefore, according to the present invention, when a predetermined temperature below the dangerous high temperature range due to a blow-by gas fire is reached, the energization of the ignition system circuit is immediately cut off to stop the ignition of the mixed gas, and further generation of blow-by gas is generated. The purpose is to prevent fires and to prevent fires.

[0011]

In view of the above problems, the present invention provides a protection device for an ignition system circuit that obtains a driving force by igniting and exploding a mixed gas of air and a combustible gas supplied to an engine, In the vicinity of the room, a means of connecting a variable resistance element having a characteristic that the resistance value suddenly rises at a predetermined temperature and the state can be maintained to the ignition system circuit is adopted.

[0012]

[Function] When the engine is emptied for a long time to generate blow-by gas of a mixed gas of unburned air and combustible gas, and the temperature in the engine room reaches a predetermined temperature below the high temperature dangerous range, it is changed. The resistance of the resistance element suddenly rises, and the energization of the ignition system circuit is cut off.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of one embodiment of the present invention will be described below with reference to FIGS. Reference numeral E denotes an automobile engine. The engine E has a structure similar to that of a known one as shown in FIG. 8, and the same parts are designated by the same reference numerals.

K is an ignition system circuit, and this ignition system circuit K
Is for igniting and exploding a mixed gas b of the air supplied to the engine E and a combustible gas to obtain a driving force, and is turned on / off by an ignition switch SW provided in a driver's seat and an igniter 2. An ignition coil 1 having a primary coil 3 and a secondary coil 4 provided so as to be opposed to the primary coil 3 so as to be electromagnetically induced by turning on / off the primary coil 3;
It is the same as the conventional ignition system circuit K'shown in FIG. 9 in that it is formed of an ignition plug d connected to the secondary coil 4 via a distributor 6.

However, in this embodiment, the ignition switch SW and the ignition coil 1 are connected via the variable resistance element 20 provided in the vicinity of the engine room EG, so that, for example, the engine E is emptied. Blow-by gas as an unburned mixed gas b of air and combustible gas temporarily accumulates in the engine E and overflows from the intake side of the engine E, so that high-temperature and high-pressure gas flows back into the engine E and the engine room When the temperature inside the EG is about to reach a high temperature dangerous zone, for example 200 ° C, when it reaches a predetermined temperature below that, for example 180 ° C,
The current to the ignition system circuit K is cut off and the temperature inside the engine room EG is prevented from rising further to protect the circuit.

The mounting of the variable resistance element 20 near the engine room EG is made of plastic or the like on the engine wire harness protector 21 provided in the engine room EG as shown in FIGS. 2 and 3, for example. An electrically insulating storage box 22 is provided so as to be attachable, and the variable resistance element 20 is held and fixed to two front and rear male terminal plates 23 and 24 which are detachably inserted into the storage box 22.

The attachment means of the storage box 22 to the wire harness protector 21 is provided with a bracket 25 of the wire harness protector 21 which is substantially T-shaped in plan view.
By providing the mounting guide wall parts 22a, 22a having a substantially L-shaped cross section on the back surface of the storage box 22, the mounting guide wall parts 22a, 22a are removably fitted into the bracket 25 so that the storage box 22 can be attached to the wire harness protector 21. Removably attached to.

Moreover, in order to mount the polymer PTC element in the storage box 22, the leg portions 23a, 24a of the two male terminal plates 23, 24 holding and fixing the polymer PTC element are stored in the storage box 22. Hole 22 provided in
b, 22b, and then the leg portions 23a, 24a in the female terminals 27, 27 attached to the tips of the electric wires 26, 26.
Install by inserting. At this time, the two male terminal plates 23 and 24 are fixed to each other by soldering a base such as nickel plating. Further, the male PTC elements are fixed to the male terminal plates 23 and 24. For example, by using a conductive adhesive, the polymer PTC element is bonded to the male terminal boards 23, 24,
24 Achieved by caulking and fixing each other or screwing.

As shown in the characteristic diagram of FIG. 4 showing the relationship between temperature and resistance, the variable resistance element 20 rapidly increases in resistance when its resistance value, which is normally several tens of mmΩ, reaches a predetermined temperature t. If the resistance value rises and the resistance value rises once,
For example, a polymer PT having the characteristic that the current to the ignition system circuit K is cut off by continuing to maintain that state.
C element is used.

As shown in FIGS. 5 and 6, the polymer PTC element is an element formed by mixing polymer 28 and carbon 29. In this polymer PTC element, the crystalline particles such as PE are mixed with the conductive particles such as carbon 29 at an appropriate ratio so that the carbon 29 mainly gathers in the crystal part and is connected to each other at normal temperature as shown in FIG. A conductive path is formed by the carbon 29 in combination, and although it is apparently conductive, the crystal part of the polymer 28 is different from that of the polymer 28 in that the expansion coefficient of the polymer 28 is different from that of the carbon 29 at high temperature as shown in FIG. As a result of the thermal expansion of the conductive material, the conductive path is divided with respect to the carbon 29, and as shown by the resistance-temperature characteristic curve A in FIG. By doing so, the power supply is cut off. By utilizing this change in resistance value and substituting the fuse function for the polymer PTC element, the conventional fuse 5'as shown in FIG. 9 can be eliminated.

At this time, by selecting and using various polymers 28 used for the polymer PTC element, it is possible to freely set the predetermined temperature t at which the resistance rapidly increases as the temperature rises. For example, when the temperature reaches 180 ° C, which is close to 200 ° C as the dangerous temperature range, the resistance value suddenly rises to a high resistance, and the polymer PTC element replaces the fuse function to interrupt the ignition system circuit K. And turn off the power. When the energization of the ignition system circuit K is cut off in this way, the drive of the engine E is stopped, the generation of blow-by gas is stopped, and the occurrence of fire is prevented.

The polymer PTC element is used for the circuit.
If you put it in series with the fire system circuit K, the circuit will be protected from overcurrent and overheating.
Can be protected. That is, in the circuit shown in FIG.
A constant voltage is applied and the load resistance (R _L) Is
Assuming that the resistance is sufficiently higher than the steady-state resistance of the child,
Exothermic-temperature curve is P_G1It is represented by a curve with a maximum value such as
To be done. P_G1= E²R_T/ (R_T+ R_L)² In addition, the environmental temperature of engine room E.G._ATo
And the heat dissipation of polymer PTC element depends on the element temperature and the ambient temperature.
T_AIs proportional to the difference between the_D
Becomes This is P_D= K (T-T_A) Can be represented. By the way
The polymer PTC element has the same amount of heat radiation and heat generation
By the way, since they are in a parallel state, as shown in FIG.
Line P_G1And P_DWhen intersects at three points, points (1) and (3) are not
A constant parallel point is created.

In normal times, the polymer PTC element is (1)
It remains parallel at the point of, but reaches an equilibrium point at point (3) if some abnormality occurs. At this time, the polymer PTC element has a high resistance and at the same time limits the current flowing in the circuit.
The decrease of the equilibrium point from point (1) to point (3) is called the trip phenomenon. Once the circuit trips, the circuit will not recover even if the abnormality is removed, and in order for the ignition system circuit K to operate normally, the voltage should be reduced to below the curve of P _G2 or the spark plug as a load in the ignition system circuit K. It is necessary to cut off the power supply to d and wait for the polymer PTC element to cool.

One embodiment of the present invention has the above-mentioned structure. For example, when the engine E is emptied and the unburned mixed gas b accumulates in the engine E and overflows from the intake side,
A mixed gas b of high temperature and high pressure air and a combustible gas flows backward in the engine E, and blow-by gas is generated to cause engine room E.
When the temperature in G reaches a predetermined temperature of 200 ° C. or less in a high temperature danger zone, for example 180 ° C., the resistance of the polymer PTC element as the variable resistance element 20 sharply increases and the ignition system circuit K is energized. Is cut off. Therefore, the drive of the engine E is stopped and the generation of blow-by gas is prevented,
The rise in temperature in the engine room EG is prevented and a fire is prevented.

[0025]

As described above, according to the present invention, when the temperature reaches a predetermined temperature below a high-temperature dangerous area which causes a fire due to blow-by gas generated by running an automobile engine, the ignition switch and the ignition coil are connected. The resistance of the variable resistance element connected between them rapidly increases, and the power supply to the ignition system circuit is quickly and surely cut off. In this way, the ignition of the mixed gas of the engine is stopped, the further generation of blow-by gas is prevented, and the fire is surely prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a perspective view showing the interior of the engine room of the automobile.

FIG. 3 is an exploded perspective view showing a state in which the variable resistance element is mounted on the wire harness protector in the engine room.

FIG. 4 is a characteristic diagram showing resistance-temperature characteristics of a polymer PTC element as a variable resistance element that constitutes this embodiment.

FIG. 5 is a tissue cross-sectional view of the polymer PTC element at the same low temperature.

FIG. 6 is a tissue cross-sectional view of the polymer PTC element at the same high temperature.

FIG. 7 is a characteristic diagram showing heat generation-temperature characteristics of the same polymer PTC element.

FIG. 8 is a cross-sectional view showing an example of a conventional automobile engine.

FIG. 9 is a circuit diagram showing an example of an ignition system circuit of an automobile engine.

[Explanation of symbols]

 20 Variable Resistance Element 21 Wire Harness Protector 22 Storage Box 23 Male Terminal Board 24 Male Terminal Board E Engine E.G Engine Room K Ignition System Circuit

[Procedure amendment]

[Submission date] April 28, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

As shown in the characteristic diagram of FIG. 4 showing the relationship between temperature and resistance, the variable resistance element 20 normally has several tens.
When the resistance value, which is mΩ , reaches a certain predetermined temperature t, the resistance value suddenly increases, and once the resistance value increases, the state is maintained and the power supply to the ignition system circuit K is cut off. Polymer PTC having the following characteristics
Use the element.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

As shown in FIGS. 5 and 6, the polymer PTC element is an element formed by mixing polymer 28 and carbon 29. In this polymer PTC element, the crystalline particles such as PE are mixed with the conductive particles such as carbon 29 at an appropriate ratio so that the carbon 29 mainly gathers in the crystal part and is connected to each other at normal temperature as shown in FIG. Combined with carbon 29 to form a conductive path
Although formed and conductive, when exposed to high temperatures,
As shown in FIG. 4, the thermal expansion of the crystal part of the polymer 28 divides the conductive path to the carbon 29 from the point that the expansion coefficients of the polymer 28 and the carbon 29 are different, and as shown in the resistance-temperature characteristic curve A of FIG. , A certain temperature t
When the temperature reaches (near the melting point of the polymer), the resistance value suddenly changes and increases, thereby cutting off the current flow. By utilizing this change in resistance value to substitute the fuse function for the polymer PTC element, the conventional fuse 5'as shown in FIG.
Can be abolished.

Claims (3)

[Claims] 1. A protection device for an ignition system circuit that obtains a driving force by igniting and exploding a mixed gas of air supplied to an engine and a combustible gas, and the ignition system circuit is provided at a predetermined temperature in the vicinity of an engine room. An ignition system circuit device characterized in that a variable resistance element having a characteristic capable of maintaining a state in which the resistance value rapidly rises is connected. 2. The ignition system circuit breaker according to claim 1, wherein the variable resistance element is a PTC element. 3. A wire harness protector for an engine is provided with an electrically insulative storage box attachable thereto, and the variable resistance element is held and fixed to two male terminal plates inserted into the storage box. The ignition system circuit breaker according to claim 1 or 2.