Internal-combustion engines – High tension ignition system – Power supply – ignition coil primary – and interrupter element...
Reexamination Certificate
2000-01-21
2001-08-28
Solis, Erick (Department: 3747)
Internal-combustion engines
High tension ignition system
Power supply, ignition coil primary, and interrupter element...
C123S599000
Reexamination Certificate
active
06279558
ABSTRACT:
INCORPORATION BY REFERENCE
The disclosure of Japanese Patent Application No. HEI 11-13578 filed on Jan. 21, 1999 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ignition apparatus of an internal combustion engine that induces current through a primary coil by rotational movement of an ignition power-generating permanent magnet based on rotation of an output shaft of the internal combustion engine, and discontinues the induced current to induce a voltage across a secondary coil, and applies the voltage induced across the second coil to an ignition plug of the internal combustion engine.
2. Description of the Related Art
A known ignition apparatus of an internal combustion engine is a magneto ignition apparatus. The magneto ignition apparatus includes a permanent magnet mounted to an output shaft of an internal combustion engine, and a primary coil disposed near the permanent magnet. Therefore, current is induced in a primary coil by changes of the magnetic field created by rotational movement of the permanent magnet. An electric line connected to the primary coil is provided with a switch that discontinues or cuts off the current through the primary coil periodically at an engine ignition timing. A great change in current, that is, discontinuation of current, induces a high voltage across the secondary coil facing the primary coil. The voltage induced in the secondary coil is applied to an ignition plug of an internal combustion engine, so that the ignition plug produces discharge.
The switch for discontinuing current through the primary coil can be operated by various control devices, for example, a microcomputer. Japanese Patent Application Laid-Open No. HEI 6-307318, as for example, discloses a construction in which a microcomputer detects a current flowing through the primary coil, and determines an ignition timing based on the detected current, and accordingly switches off a transistor switch.
Normally, the microcomputer or the like is driven by an external power source. Therefore, if the external power source fails, it becomes impossible to perform ignition. Furthermore, a failure of the computer itself also makes it impossible to perform ignition.
Therefore, it is necessary to perform the aforementioned switching on and off by using a more reliable hardware circuit while omitting an external power source. In a conventional circuit, therefore, a cam is provided on an output shaft of the engine. The aforementioned switch is formed by a mechanical breaker that is on/off-controlled by the cam.
However, mechanical breakers are likely to be severely damaged by arc discharge and the like, and therefore have relatively short service lives and require many man-hours of check and maintenance.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an internal combustion engine ignition apparatus that does not require an external power source and can easily be checked and maintained.
One aspect of the invention provides an ignition apparatus of an internal combustion engine including a generator that has a primary coil and a secondary coil and that generates an induced voltage in the secondary coil by using an induced current that flows through the primary coil based on rotation of an output shaft of the internal combustion engine, a device for generating the induced voltage in the secondary coil by discontinuing the induced current and for applying the induced voltage to an ignition plug of the internal combustion engine, a semiconductor switching element that controls one of discontinuation and conduction of a current through the primary coil, and an element drive signal generation device for generating a signal that switches the semiconductor switching element on and off based on the rotation of the output shaft. The element drive signal generation device generates an element drive signal so that the semiconductor switching element switches from an on-state to an off-state at a timing at which ignition of the ignition plug is to be performed.
Therefore, the above-described ignition apparatus generates a control current that switches the semiconductor switching element on and off based on rotation of the output shaft of the internal combustion engine. Hence, the ignition apparatus does not require an external power source for ignition control. Furthermore, since the signal that switches the semiconductor switching element on and off is generated based on revolution of the internal combustion engine, the ignition apparatus allows easy and reliable setting of ignition timing. Further, the ignition apparatus does not require an external power source or a special drive circuit, but requires only a simple circuit construction.
The semiconductor switching element may be a MOSFET. MOSFETs have smaller conduction resistance when in an on-state than other types of switching elements such as bipolar transistors. Therefore, a MOSFET switching element provides performance (small resistance) similar to that of a breaker at the time of conduction. The on-state and off-state (conductive state and non-conductive state) of a MOSFET can be established by increasing the gate-source voltage to or above a threshold voltage. Since the current consumption of a MOSFET is very small, the control thereof is very easy. Therefore, unlike bipolar transistors, the MOSFET switching element does not need conduction of a relatively large base current in accordance with the load current. Furthermore, the MOSFET switching element has a quicker response speed than bipolar transistors or the like. Hence, the operation timing of the MOSFET switching element can be set similarly to that of a conventional breaker.
The ignition apparatus according to the invention may further include a comparator that converts an analog signal generated by the element drive signal generation device, such as an electromagnetic pickup or the like, into a digital signal and that outputs an output signal that switches the conductor switching element on and off, and a comparator operating power source portion that is electrically charged by an induced current generated by rotation of an ignition power generating permanent magnet and that supplies the comparator with an operating power.
Therefore, a sine waveform signal generated by the element drive signal generation device, such as an electromagnetic pickup, is converted into a rectangular waveform signal, which is applied to the switching element. Therefore, the on/off operation of the switching element becomes similar to that of a mechanical breaker, so that the switching loss of the switching element can be considerably reduced. Furthermore, it is unnecessary to provide any special power source for the comparator.
The ignition apparatus may further include an external power source that supplies a current to the primary coil, and a second element drive signal generation device for, when the current from the external power source is supplied to the primary coil, generating a second element drive signal that controls switch on and off of the semiconductor switching element, independently of the element drive signal.
Therefore, it becomes possible to substantially freely control the ignition timing and optimally change the ignition timing in accordance with the operating condition of the internal combustion engine. For example, there normally is a requirement that the ignition timing be closer to the top dead center during start of the engine than during normal engine operation. This requirement can be achieved by using the second element drive signal. The ignition timing can also be changed during normal engine operation. If the second element drive signal is absent, normal ignition can be performed based on the voltage induced by the permanent magnet.
Another aspect of the invention provides an ignition apparatus of an internal combustion engine including a generator that has a primary coil and a secondary coil and that
Kenyon & Kenyon
Solis Erick
Toyota Jidosha & Kabushiki Kaisha
LandOfFree
Ignition apparatus of internal combustion engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ignition apparatus of internal combustion engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ignition apparatus of internal combustion engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2549544