JP2009174441A - Igniter of ignition coil for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an igniter of an ignition coil for an internal combustion engine, preventing excessive current from being intermittently led to flow into the ignition coil for the internal combustion engine when a power transistor is short-circuited and the igniter is continuously energized. <P>SOLUTION: This igniter 1 of the ignition coil for the internal combustion engine is provided with the power transistor 4 controlling current-carrying state or non-current-carrying state of primary current flowing in the primary coil 31 of a coil-iron core assembly 3, according to an ignition control signal from an engine control device 2. A nonlinear type with an electric resistance value suddenly risen when exceeding 150°C is employed as a PTC thermistor 5 with the electric resistance value increased in association with temperature rise, and is arranged in a portion in the vicinity of the power transistor 4 and between the primary coil 31 and the collector portion 41 of the power transistor 4 connected to the primary coil 31. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an igniter for an ignition coil for an internal combustion engine used in an internal combustion engine such as an automobile. By disposing a current limiting element, an electrical resistance value is rapidly increased when a power transistor is short-circuited, and an excessive current is generated. TECHNICAL FIELD The present invention relates to an igniter for an internal combustion engine ignition coil that can prevent the engine from intermittently flowing into the internal combustion engine ignition coil.

  The ignition coil for an internal combustion engine is arranged for each cylinder of the engine. A primary coil, a secondary coil disposed outside the primary coil, and the secondary coil and the primary coil are magnetized in an insulating case. A coil-core assembly consisting of an electrically coupled iron core is housed, and further, an igniter comprising at least a power transistor controlling a primary current flowing in the primary coil in the coil-core assembly is housed, and It is configured by being filled with an insulating resin and cured. In general, dimensional restrictions required from other engine parts and the like are severe, and miniaturization is required. In addition, in order to bring about a severe thermal environment, such as the operating temperature is below 30 ° C to 130 ° C, various designs to guarantee sufficient durability for the igniter housed in the insulation case. Consideration is being considered.

Here, a conventional igniter for an ignition coil for an internal combustion engine, for example, a one-chip igniter, includes a power transistor that controls energization / non-energization of a primary current flowing through the primary coil by on / off, and a primary current flowing through the primary coil. The circuit element that restricts the above is developed in one semiconductor chip. The power transistor includes a gate portion connected to the engine control device, an emitter portion connected to the ground, and a collector portion connected to the primary coil. The circuit element protects the power transistor by limiting the current flowing from the collector part to the emitter part of the power transistor.
The igniter prevents abnormal heat generation by avoiding continuous energization by circuit elements, prevents deterioration and destruction of the power transistor that is a component, and thus prevents melting and ignition of the ignition coil for the internal combustion engine. Yes. Inventions relating to such an igniter for an ignition coil for an internal combustion engine have been proposed in, for example, Patent Document 1 and Patent Document 2 below.
JP 2001-248529 A JP 2000-297732 A

  In the case of an engine system such as an automobile, if the ignition coil for the internal combustion engine or the igniter itself malfunctions, these are arranged for each cylinder of the engine. This is constructed so that a state where the vehicle can be evacuated is maintained and a dangerous state due to an engine stop is avoided.

  However, the conventional ignition coil igniter for an internal combustion engine is excessive because the above-mentioned circuit element protection mechanism does not work when a short circuit (failure) occurs between the collector and emitter of the power transistor. There is a problem that current is not limited or forcibly cut off and becomes abnormally heated due to continuous energization, resulting in melting of the ignition coil for internal combustion engines, ignition, and engine malfunction. In particular, in the worst case, the vehicle fuse is blown by abnormal heat generation due to excessive current, and since the vehicle fuse of the engine system is usually one system, the engine is stopped and it is impossible to evacuate. There was a problem that it could fall into a state.

  The present invention has been proposed in view of the above circumstances, and even when any short circuit (failure) occurs between the collector and emitter of the power transistor, the electric resistance is provided by mounting the current limiting element. An object of the present invention is to provide an ignition coil igniter capable of rapidly increasing the value and preventing an excessive current from intermittently flowing into the internal combustion engine ignition coil.

  In order to achieve the above object, an igniter for an ignition coil for an internal combustion engine according to the present invention includes a power transistor for controlling energization / non-energization of a primary current flowing in a primary coil in accordance with an ignition control signal from an engine control device. In the igniter of the ignition coil for an internal combustion engine provided, a current limiting element whose electrical resistance value increases with a temperature rise is provided between the primary coil and the collector part of the power transistor, or an emitter part of the power transistor. It is characterized by being arranged between the ground.

  Furthermore, it is preferable that the current limiting element is of a non-linear type whose electric resistance value increases abruptly when a certain temperature is exceeded.

  More preferably, the current limiting element is disposed on the chip where the power transistor is disposed or in the vicinity of the power transistor.

  According to the present invention, in an igniter for an internal combustion engine ignition coil having a power transistor that controls energization / non-energization of a primary current flowing through a primary coil in accordance with an ignition control signal from an engine control device, an electrical resistance increases with increasing temperature. Since the current limiting element whose value increases is disposed between the primary coil and the collector portion of the power transistor, or between the emitter portion of the power transistor and the ground, the collector portion and the emitter portion of the power transistor are disposed. Even if the igniter heats up abnormally due to some short circuit (failure), the electric resistance value of the current limiting element increases and the electric resistance value of the igniter increases, so an excessive current is intermittently applied to the ignition coil for the internal combustion engine. It can be prevented from flowing. As a result, it is possible to prevent the internal combustion engine ignition coil from being melted and ignited, and the engine malfunction, and in particular, it is possible to prevent the vehicle fuse from fusing due to abnormal heat generation due to excessive current, causing engine stop and evacuation. It is possible to ensure the safety of an engine system such as an automobile by preventing the vehicle from falling into a very dangerous state where traveling is impossible.

  Furthermore, since the current limiting element is of a non-linear type in which the electrical resistance value suddenly increases when a certain temperature is exceeded, the electrical resistance value of the igniter suddenly increases and becomes excessive only when the igniter abnormally generates heat. It is possible to prevent the current from intermittently flowing into the internal combustion engine ignition coil, and it is possible to reliably supply the necessary amount of current to the internal combustion engine ignition coil during normal operation. That is, it is possible to provide an ignition coil igniter for an internal combustion engine with stable operation and high reliability.

  Further, since the current limiting element is arranged on the chip where the power transistor is arranged or in the vicinity of the power transistor, the igniter abnormality based on a short circuit (failure) between the collector part and the emitter part in the power transistor. Since the current limiting element can quickly detect heat generation and increase its electrical resistance value, the electrical resistance value of the igniter should be increased quickly to prevent an overcurrent from quickly flowing into the ignition coil for the internal combustion engine. Can do. This can effectively prevent the internal combustion engine ignition coil from being melted, ignited, and engine malfunction, and in particular, can prevent the vehicle fuse from fusing due to abnormal heat generation due to excessive current. Therefore, the safety of the engine system such as an automobile can be ensured by preventing the vehicle from falling into a very dangerous state in which retreating is impossible.

Hereinafter, some embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic circuit diagram of a first embodiment of the ignition coil igniter according to the present invention. FIG. 2 is a schematic circuit diagram of a second embodiment of the ignition coil igniter according to the present invention. FIG. 3 is a schematic circuit diagram of a third embodiment of the ignition coil igniter according to the present invention. FIG. 4 is a schematic circuit diagram of a fourth embodiment of the ignition coil igniter according to the present invention. is there.

(First Example)
The igniter 1 for an internal combustion engine ignition coil according to the present invention is configured to apply a primary current flowing through the primary coil 31 of the coil-iron core assembly 3 in accordance with an ignition control signal from the engine control device 2 as shown in FIG. In an igniter 1 for an ignition coil for an internal combustion engine having a power transistor 4 for controlling non-energization, a current limiting element, for example, a PTC thermistor 5 whose electric resistance value increases as the temperature rises is disposed inside. Is.

  The PTC thermistor 5 is disposed in the vicinity of the power transistor 4 inside the igniter 1 and between the primary coil 31 and the collector portion 41 of the power transistor 4 connected to the primary coil 31. Yes. Further, the PTC thermistor 5 is a non-linear type in which the electrical resistance value suddenly increases when a certain temperature, for example, 150 ° C. is reached.

  Here, in the igniter 1 of the ignition coil for an internal combustion engine according to the present invention, a case where some short circuit (failure) occurs between the collector part 41 and the emitter part 42 in the power transistor 4 will be described.

  When any short circuit (failure) occurs between the collector part 41 and the emitter part 42 in the power transistor 4, the igniter 1 is in a continuous energization state in which the primary current continues to flow through the primary coil 31. The igniter 1 that is in a continuous energization state generates heat, but when it reaches 150 ° C., in the vicinity of the power transistor 4, the primary coil 31 and the collector portion 41 of the power transistor 4 connected to the primary coil 31 The electrical resistance value of the PTC thermistor 5 disposed between the two increases rapidly. As a result, the electrical resistance value of the igniter 1 also rapidly increases, so that an excessive primary current does not flow to the primary coil 31, that is, an excessive current does not flow intermittently to the internal combustion engine ignition coil. As a result, the igniter 1 for an internal combustion engine ignition coil according to the present invention has an excessive current in the internal combustion engine ignition coil even if a short circuit (failure) occurs between the collector 41 and the emitter 42 in the power transistor 4. Since it does not flow intermittently, the vehicle fuse 6 will not be blown, the engine will stop, and it will not fall into a very dangerous state in which retreating is impossible.

  Therefore, in the ignition coil igniter 1 for an internal combustion engine according to the present invention, the PTC thermistor 5 whose electric resistance value increases as the temperature rises is disposed inside, particularly in the vicinity of the power transistor 4 and the primary coil 31. Since it is disposed between the collector part 41 of the power transistor 4 connected to the primary coil 31, some short circuit (failure) occurs between the collector part 41 and the emitter part 42 in the power transistor 4, and the igniter 1 is Even if the heat is generated, when the temperature reaches 150 ° C., the electrical resistance value of the PTC thermistor 5 increases rapidly, so that the electrical resistance value of the igniter 1 increases rapidly and an excessive current is intermittently applied to the ignition coil for the internal combustion engine. It can be prevented from flowing. In particular, since the PTC thermistor 5 is disposed in the vicinity of the power transistor 4, it is possible to quickly detect that the igniter 1 has generated heat exceeding 150 ° C., and to rapidly increase its electric resistance value. The igniter 1 for an internal combustion engine ignition coil according to the present invention does not blow the vehicle fuse 6 even during abnormal heat generation exceeding 150 ° C. Can be prevented from falling into a dangerous state.

  The ignition coil igniter 1 for the internal combustion engine according to the present invention employs a PTC thermistor 5 whose electric resistance value suddenly increases when it reaches 150 ° C., so what causes the abnormal heat generation? However, at the time of abnormal heat generation exceeding 150 ° C., the electrical resistance value of the igniter 1 can be rapidly increased, and an excessive current can be prevented from intermittently flowing into the internal combustion engine ignition coil. And since the vehicle fuse 6 is not blown out, it is possible to prevent the engine from being stopped and falling into a very dangerous state in which retreating is impossible.

(Second embodiment)
As shown in FIG. 2, the igniter 1 of the internal combustion engine ignition coil in the second embodiment is connected to the PTC thermistor 5 in the vicinity of the power transistor 4 inside the igniter 1 and to the ground 7. The only difference from the first embodiment is that the power transistor 4 is disposed between the emitter section 42 and the power transistor 4. Other configurations and their effects are the same as in the first embodiment.

(Third embodiment)
Further, as shown in FIG. 3, the igniter 1 for the internal combustion engine ignition coil in the third embodiment includes a PTC thermistor 5 in the vicinity of the power transistor 4 in addition to the configuration of the igniter 1 in the first embodiment. This is a configuration further arranged between the control device 2 and the gate portion 43 of the power transistor 4 connected to the engine control device 2. Then, in addition to the effect in the first embodiment, in addition to the case where a short circuit occurs between the gate part 43 and the emitter part 42 of the power transistor 4, the pulse of the ignition control signal from the engine control device 2 side is not abnormal. The PTC thermistor 5 further disposed between the engine control device 2 and the gate portion 43 of the power transistor 4 connected to the engine control device 2 when the igniter 1 is heated for a long time. Is detected and the electric resistance value is increased, so that the driving voltage of the igniter 1 is lowered, and therefore the current flowing between the collector part 41 and the emitter part 42 of the power transistor 4 is lowered or cut off. It is possible to prevent the excessive current from flowing intermittently to the ignition coil for the internal combustion engine.

(Fourth embodiment)
Further, as shown in FIG. 4, the igniter 1 of the internal combustion engine ignition coil in the fourth embodiment includes a PTC thermistor 5 as a power transistor as in the third embodiment in addition to the configuration of the igniter 1 in the second embodiment. 4 is a configuration further disposed between the engine control device 2 and the gate portion 43 of the power transistor 4 connected to the engine control device 2. If it does so, in the igniter 1 of the ignition coil for internal combustion engines in 4th Example, in addition to the effect in 2nd Example, the effect similar to 3rd Example can be acquired.

  The PTC thermistor 5 exemplified in the first to fourth embodiments has been described as being disposed in the vicinity of the power transistor 4, but includes at least the power transistor 4 that is an internal heat source of the igniter 1. By disposing on the chip, it is possible to quickly detect abnormal heat generation of the igniter and increase its electric resistance value.

  As mentioned above, although some embodiment which concerns on this invention was explained in full detail, this invention is not limited to the said embodiment. The present invention can be modified in various ways without departing from the scope of the claims. For example, in the above embodiment, the PTC thermistor is used as the current limiting element. However, as long as the current limiting element that can utilize the property that resistance increases due to heat generation and current does not flow easily is used as appropriate. The current limiting element can be used. In particular, if a current-limiting element is used that has a non-linear operation in which the resistance suddenly increases when a certain temperature is exceeded, an excessive current is generated only when the igniter generates heat abnormally. Therefore, it is possible to reliably supply a necessary amount of current to the ignition coil for the internal combustion engine during normal operation, which is a desirable embodiment.

  Further, by using the current limiting element as a circuit protection element, if other safety is cleared, the vehicle fuse of the engine system can be eliminated. That is, it can be expected to construct an economical engine system that does not require a vehicle fuse.

1 is a schematic circuit diagram of a first embodiment of an igniter for an ignition coil for an internal combustion engine according to the present invention. It is a schematic circuit diagram of the 2nd example in an igniter of an ignition coil for internal-combustion engines concerning the present invention. FIG. 6 is a schematic circuit diagram of a third embodiment of the igniter for an ignition coil for an internal combustion engine according to the present invention. FIG. 7 is a schematic circuit diagram of a fourth embodiment of the igniter for an internal combustion engine ignition coil according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Igniter 2 Engine control apparatus 3 Coil-core assembly 31 Primary coil 4 Power transistor 41 Collector part 42 Emitter part 43 Gate part 5 PTC thermistor 6 Vehicle fuse 7 Ground

Claims (3)

In an igniter for an internal combustion engine ignition coil including a power transistor that controls energization / non-energization of a primary current flowing in a primary coil in response to an ignition control signal from an engine control device,
A current limiting element that increases in electrical resistance as the temperature rises is disposed between the primary coil and the collector of the power transistor, or between the emitter of the power transistor and the ground,
An ignition coil igniter for an internal combustion engine. In the igniter of the ignition coil for an internal combustion engine according to claim 1,
The current limiting element is of a non-linear type whose electrical resistance value increases rapidly when a certain temperature is exceeded,
An ignition coil igniter for an internal combustion engine. In the igniter of the ignition coil for an internal combustion engine according to claim 1 or 2,
The current limiting element is disposed on a chip on which the power transistor is disposed or in the vicinity of the power transistor.
An ignition coil igniter for an internal combustion engine.

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