Electricity: measuring and testing – Internal-combustion engine ignition system or device – Magneto
Reexamination Certificate
2001-03-01
2003-03-18
Le, N. (Department: 2858)
Electricity: measuring and testing
Internal-combustion engine ignition system or device
Magneto
C123S599000
Reexamination Certificate
active
06534987
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magneto-system firing apparatus, and more particularly to a magneto-system firing apparatus mounted on an aircraft and having a breaker failure detecting portion which is capable of detecting an abnormal state of the make/break operation of the breaker.
2. Description of the Related Art
In general, a battery type firing apparatus is applied to an engine for an automobile, but a self-generatable magneto-system firing apparatus is used in the aircraft from the viewpoint of safety.
As shown in
FIG. 8
, the magneto-system firing apparatus of this type includes a permanent magnet
11
disposed on a rotary shaft
10
that interlocks with a crank shaft of an engine, a primary coil
13
that forms an ignition coil wound around an iron core
12
which is so disposed as to surround the permanent magnet
11
, a secondary coil
14
larger in turn ratio than the primary coil
13
, a cam mechanism
15
connected to the primary coil
13
and disposed on the rotary shaft
10
, and a mechanical breaker
18
which is driven by the cam mechanism
15
, and makes intermittent a current generated in the primary coil
13
due to the make/break operation of a contact point
17
which is abutted against the surface of the cam
16
or spaced apart from the cam
16
.
In the magneto-system firing apparatus
19
of this type, in the case where a low-voltage current is generated as an inductance current in the primary coil
13
due to the rotation of the permanent magnet
11
interlocked with the rotation of the crank shaft, the breaker
18
is driven by the cam mechanism
15
so as to be actuated so that the contact point
17
is opened, and the low-voltage current in the primary coil
13
is broken, as a result of which a high-voltage current is induced in the secondary coil
14
, and the high voltage is applied to spark plugs (not shown) disposed in the respective cylinders through a distributor
20
to cause spark discharge at spark gaps and fire an air-fuel mixture in the cylinders, thereby driving pistons. In the figure, reference numeral
21
denotes a capacitor and
22
is a spark plug.
In the breaker
18
thus structured, since the above contact point
17
is repeatedly physically abutted against and spaced apart from the surface of the cam
16
to make and break the current that flows in the primary coil
13
, there is a possibility that the contact point
17
is burned and damaged while it is used. In the case where the contact point
17
is thus burned and damaged, even if the crank reaches a predetermined rotating angle at a spark timing, the breaker
18
does not appropriately conduct the make/break operation, so that the current in the primary coil
13
is not broken, with the results that because the high-voltage current is not induced in the secondary coil
14
, there is a case in which the spark discharge does not occur in the spark plug, and the air-fuel mixture within the cylinder is not fired.
In order to prevent the above situation, in an engine for an aircraft, there is formed a so-called dual ignition system having two magneto-system firing apparatuses
19
for each of the piston cylinders from the viewpoint of safety. A pilot is under an obligation to conduct the stop operation with respect to the two magneto-system firing apparatuses
19
mounted on the respective cylinders, to confirm that the number of revolutions of an engine is lowered a certain degree, and to confirm whether or not the respective magneto-system firing apparatuses
19
are normally actuated, before every time the aircraft takes off. The above confirming operation must be conducted every time before flying which is troublesome.
Also, at the time of inspections on the ground, the operation of inspecting the breakers is periodically conducted every several tens hours, and in the case where the contact point
17
is burned and damaged, it is necessary to replace the breaker
18
with a new one. Thus, the inspecting and maintaining operation is also complicated. Under the above circumstances, up to now, it is desirable to provide a means for detecting the burning damage and deterioration of the breaker
18
of the magneto-system firing apparatus
19
at a real time.
However, it is difficult to provide the means for detecting the abnormal operation of the breaker
18
for the following reasons.
In order to judge whether or not the contact point
17
of the breaker
18
is normally actuated, there is proposed, for example, a manner in which a circuit that can detect the resistance value of the breaker
18
is disposed in the breaker
18
, and the respective resistance values at the make/break time of the contact point
17
are measured, and whether or not the contact point
17
is appropriately made and broken, is judged on the basis of a change in the resistance value.
In this case, the primary coil
13
of the ignition coil is connected in parallel with the breaker
18
, and the impedance of the primary coil
13
is about 0.65 to 0.7 &OHgr;. Since the breaker
18
is influenced by the impedance when the breaker
18
is made, the resistance value detected on the breaker
18
when the breaker
18
is broken becomes about 0.65 to 0.7 &OHgr;, likewise.
On the other hand, when the breaker
18
is made, the resistance value of the breaker
18
is 0 &OHgr;, but since a difference in the resistance between the make and break states is slight, it is difficult to distinguish the make state from the break state, and to judge whether or not the make/break operation is appropriately conducted.
Also, as described above, when the breaker
18
is broken, the low-voltage current in the primary coil
13
is interrupted with the result that a large serge voltage is generated in the secondary coil
14
. Therefore, in the case where a detecting circuit and an electronic parts for detection are connected to the breaker
18
, since the detecting circuit and the electronic parts cannot withstand the serve voltage, it is difficult to connect the detecting circuit and the electronic parts for detection to the breaker
18
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a magneto-system firing apparatus which is capable of detecting an abnormal state rapidly in the case where the breaker is damaged or the like, and there occurs abnormality in the make/break operation of the contact point.
Also, another object of the present invention is to provide a magneto-system firing apparatus that detects the abnormality of the make/break operation on the basis of information related to an angle of a crank shaft of an engine and information related to the make/break operation of the breaker.
In order to achieve the above objects, there is provided a magneto-system firing apparatus, comprising: a magnet fixed to a rotary shaft that interlocks with a crank shaft of an engine; a primary coil to which a low-voltage current that is generated due to the rotation of the magnet is supplied; a breaker which is connected to the primary coil and interrupts the low-voltage current supplied to the primary coil by its break operation; a secondary coil in which a predetermined voltage is induced due to the current interruption caused by the break operation of the breaker to actuate the firing apparatus by application of the voltage generated in the secondary coil; a crank angle detecting portion for detecting the rotating angle of the crank shaft; a breaker make/break state detecting portion for detecting the make/break state of the breaker; and a breaker failure detecting device having a breaker make/break abnormality detecting portion which is capable of detecting the abnormal state of the breaker make/break operation on the basis of information from the crank angle detecting portion and the breaker make/break state detecting portion.
Accordingly, in the present invention, the breaker make/break abnormality detecting portion conducts judgment on the basis of information related to the crank angle outputted from the crank angle detecting portion and i
Kerveros James
Le N.
Oliff & Berridg,e PLC
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