Electricity: measuring and testing – Internal-combustion engine ignition system or device
Reexamination Certificate
2000-07-18
2002-10-01
Sherry, Michael (Department: 2829)
Electricity: measuring and testing
Internal-combustion engine ignition system or device
C324S392000, C324S391000, C073S116070
Reexamination Certificate
active
06459267
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cylinder identifying apparatus for combustion engine used to identify cylinders, to be controlled, of a multi-cylinder combustion engine.
2. Discussion of Background
In combustion engines, particularly combustion engines equipped in vehicles, an electronic controlling device, controlling injection timing and an injection quantity of fuel, ignition timing, and so on, for avoiding environmental contamination caused by exhaust gas and for improving economy such as an output characteristics with respect to fuel consumption. The electronical controlling device is further used to control various portions of the combustion engines. Therefore, the cylinders, to be controlled, are required to be controlled to perform these controls.
FIGS. 8 through 14
explain an example of a structure and an operation of a conventional cylinder identifying apparatus for a combustion engine, wherein the combustion engine has four cylinders as an example.
In order to identify the cylinders to be controlled, a signal in synchronism with rotation of the combustion engine is used. Ordinarily, a crank angle signal, obtained from a rotational angle sensor located in a crankshaft or cam shaft of a combustion engine, is used.
FIGS. 8 and 9
illustrate a structure of a first conventional combustion engine. Numerical reference
1
designates a crankshaft of a combustion engine (not shown) or a rotational shaft rotating in synchronism with a camshaft. Numerical reference
2
designates a rotational disk, fixed to the rotational shaft, wherein the rotational disk
2
has a plurality of windows
3
at predetermined positions, and one
3
a
of the windows is set to be asymmetric with the other windows
3
. Numerical reference
4
designates a light-emitting diode (LED). Numerical reference
5
designates a photodiode receiving an output light from the LED
4
through the windows
3
and
3
a
. Numerical reference
6
designates an amplifier, amplifying an output signal from the photodiode
5
. Numerical reference
7
designates an output transistor having an opened collector, wherein the output transistor works as a crank angle sensor
8
.
In thus constructed crank angle sensor, when the rotational disk
2
rotates in synchronism with the crankshaft of the combustion engine, a signal illustrated in
FIG. 10
is obtained in the photodiode
5
by the output light from the LED
4
through the windows
3
and
3
a
. The widths of the signals are respectively determined by lengths in a rotational direction of the windows
3
and
3
a
. These signals include a plurality of signals having signal widths of t
0
corresponding to the windows
3
, and a signal for identifying a specific cylinder having a signal width of t
1
corresponding to the window
3
a
. Provided that the signal t
1
for identifying the specific cylinder is provided for identifying a first cylinder, an order of the signals is, for example, a first cylinder, a third cylinder, a fourth cylinder, and a second cylinder, which is an order of igniting the combustion engine. For example, the signal t
0
has a signal width between 75° before top dead point, hereinbelow referred to as B
75
, and 5° before top dead point, hereinbelow referred to as B
5
. For example, the signal t
1
is set to have a signal width between B
75
and 5° after top dead point, hereinbelow referred to as A
5
.
FIG. 11
is a block chart illustrating a structure of a signal processing circuit. Numerical reference
8
designates the crank angle sensor described above. Numerical reference
9
designates an interface circuit, supplying the signal outputted from the crank angle sensor
8
in
FIG. 10
to a microcomputer.
FIG. 12
is a flow chart illustrating an operation of the microcomputer. The microcomputer
10
identifies the cylinders by receiving the signals illustrated in
FIG. 10
as follows.
In Step
101
, a width t
1
or t
0
of a high level portion of the signal inputted from the crank angle sensor
8
and a period T of the signal from a previous rising-up and a present rising-up of the signal are measured, where, Hereinbelow, the widths t
1
and t
0
are inclusively referred to as t. Succeedingly, a ratio t/T between the signal width t and the period T. measured in Step
101
, is operated in Step
102
. In Step
103
, an average threshold value &agr; n satisfying t
0
/T>&agr;>t
1
/T is obtained from the result of t/T as follows:
&agr;
n
=(1
−k
)&agr;
n
−1
+k
(
t/T
)
n,
where reference k denotes a constant.
In Step
104
, t/T obtained in the Step
102
and &agr;n obtained in the Step
103
are compared. When t/T−&agr;n>0, the present signal width is determined to be t
1
to know the specific cylinder. Thereafter, in Step
105
, a cylinder identifying flag is set, when t/T−&agr;n<0, it is judged that the present signal is t
0
, indicating that the signal is not for the specific cylinder, the cylinder identifying flag is not set. In
FIG. 10
, the signal identifying flag is set in a control of the first cylinder, and thereafter the third cylinder, the fourth cylinder, and the second cylinder are sequentially controlled in the order of igniting the combustion engine with respect to succeeding signals.
FIG. 13
illustrates a schematic structure of a second conventional cylinder identifying apparatus. In the second conventional apparatus, a crank angle sensor
11
includes a rotating magnetic material
12
having a plurality of protruding teeth
12
a
around an outer periphery thereof, the rotating magnetic material
12
is attached to a cam shaft, rotating in synchronism with a crankshaft of a combustion engine, and a signal generator
13
, arranged with the teeth
12
a
with a gap, for generating a signal depending on a change of a magnetic resistance of the gap, wherein the signal from the crank angle sensor
11
is supplied to a microcomputer
10
through an interface circuit
9
.
The teeth
12
a
formed in the rotating magnetic material
12
are arranged with, for example, an interval of 10° of a rotational angle of the crankshaft. As illustrated in
FIG. 13
, in predetermined positions, the teeth
12
a
are thinned out such that an interval between adjacent teeth
12
a
is 30° in a portion
12
b
, an interval between adjacent teeth
12
a
is 30° in a portion
12
c
, and the portions
12
b
and
12
c
are continuous to lack a signal pulse waveform, generated by the signal generator
13
at these portions.
The signal waveform is illustrated in
FIGS. 14
a
and
14
b
, wherein a case that a first cylinder and a fourth cylinder are simultaneously ignited, and a second cylinder and a third cylinder are simultaneously ignited is illustrated as an example.
FIG. 14
a
shows a signal waveform inputted in the microcomputer
10
from the crank angle sensor
11
through the interface circuit
9
, wherein signals are pulses having an interval of 10°. In portions corresponding to the first and fourth cylinders, there is the thinned-out portion of 30° just before the signal at B
35
, and two continuous thinned-out portions exist just before and just after the signal B
35
at the second and third cylinders.
The microcomputer
10
operates each signal interval, and judges which signals belong to a group of the first and fourth cylinders or a group of the second and third cylinders depending on a ratio between a previous signal interval and a present signal interval, counts these signals to detect B
75
signal and B
5
, starts processing of an ignition timing and a fuel injection timing, as illustrated in
FIG. 14
b
, and resets counting-up after counting signals corresponding to two revolutions of the crankshaft in order to prepare for processing of coming two revolutions.
However, in the conventional cylinder identifying apparatuses, when a noise signal is superposed on a nomal signal by a noise from a power source, determination of the cylinders by a signal width and a signal interval becomes erroneous, and a fuel is supplied to wrong cylinders and wrong cyl
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