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Claims  |
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What is claimed is:
1. An electrical control apparatus adapted for use with a combustion engine
having an output shaft driven by mechanical energy converted from heat
energy caused by the combustion of an air-fuel mixture, said engine
including first and second control means for controlling the combustion of
said air-fuel mixture in accordance with changes of a condition of said
engine, said apparatus comprising:
a first electrical circuit for generating an electrical signal in the form
of a binary number, said signal indicating a condition of said engine as
of a selected instant in time during operation of said engine;
a digital computer for repetitively and sequentially calculating first and
second values corresponding to respective settings of said first and
second control means by receiving therein said electrical signal, said
computer being programmed to calculate said first and second values from a
first function describing a desired relationship between the condition of
said engine and the setting of said first control means and from a second
function describing another desired relationship between the condition of
said engine and the setting of said second control means;
a second electrical circuit coupled between said digital computer and said
first and second control means for converting said first and second values
into the settings of said first and second control means;
a detector for generating a synchronized pulse which is synchronized with
and in response to the rotation of said output shaft, said computer
initiating calculation of said first value in response to receipt of said
synchronized pulse;
a clock circuit for generating at least one clock pulse in a predetermined
time interval, said computer initiating calculation of said second value
in response to receipt of said clock pulse; and
an interrupt controller for receiving said synchronized pulse and said
clock pulse and for causing said computer to initiate calculation of said
first value upon receiving said synchronized pulse during the calculation
of said second value in said computer, and to subsequently complete the
calculation of said second value after said first value has been
calculated.
2. An electrical control apparatus as claimed in claim 1, wherein said
first control means includes means for controlling the amount of the
air-fuel mixture metered into said engine and means for controlling the
spark-ignition timing of said engine, and wherein said first electrical
circuit includes means for generating a binary number electrical signal
indicating the rotational speed of said output shaft during operation of
said engine.
3. An electrical control apparatus as claimed in claim 1, wherein said
second control means includes means for recirculating exhaust gases caused
by the combustion of the air-fuel mixture into said engine and said first
electrical circuit includes means for generating a binary number
electrical signal indicating changes of in the coolant temperature of said
engine.
4. An electrical control apparatus as claimed in claim 1, wherein said
digital computer includes means for repetitively calculating a third value
to sequentially compensate said first and second values by receiving said
electrical signal, said computer being further programmed to calculate
said third value from a third function describing a desired relationship
between the condition of said engine and said first and second values.
5. An electrical control apparatus as claimed in claim 4, wherein said
clock circuit comprises a frequency divider for converting a timing pulse
issued from said computer into at least two clock pulses for causing said
computer respectively to perform the calculations of said second and third
values in said computer, said clock pulses being different in frequency in
such a manner that the frequency of a first clock pulse is larger than
that of a second clock pulse, and wherein said interrupt controller is
connected to receive said synchronized pulse and said first and second
clock pulses so as to cause said computer to calculate said first value
upon receiving said synchronized pulse during the calculation of said
third value and to subsequently calculate said second value upon receiving
said second clock pulse after calculating said first value, whereafter
said interrupt controller causes said computer to complete calculation of
said third value after completion of the calculation of the second value.
6. An electrical control apparatus as claimed in claim 1, wherein the time
interval of said clock pulse is larger than that of said synchronized
pulse generated from said detector during the idling of said engine.
7. An electrical control apparatus as claimed in claim 1, wherein said
detector comprises a transducer electrically operated in response to the
rotational speed of said output shaft to generate angular pulses, a
comparator for comparing each of said angular pulses with a reference
signal, and a frequency divider for frequency dividing each output pulse
issued from said comparator to generate said synchronized pulses having a
variable time interval in accordance with changes in the rotational speed
of said output shaft.
8. An electrical control apparatus as claimed in claim 7, wherein said
detector further comprises:
a counting circuit having a counter for receiving said output pulses from
said comparator to count time intervals of said output pulses and a
register for transferring the output of said counter as a binary number
speed signal to said computer in response to an instruction word
therefrom; and
a control circuit for transferring the output pulses from said comparator
to said counter of said counting circuit in accordance with said
instruction word.
9. An electrical control apparatus as claimed in claim 1, wherein said
clock circuit comprises a frequency divider for converting a timing pulse
issued from said computer into at least one clock pulse with a
predetermined frequency.
10. An electrical control apparatus as claimed in claim 1, wherein said
interrupt controller comprises first and second registers for selectively
generating an output signal of a high-level upon receiving said
synchronized pulse and said clock pulse; an interruption mask for
generating at its first and second terminals output signals of a low-level
during the calculation of said first value in said computer and for
generating at its first terminal an output signal of a high-level and at
its second terminal an output signal of a low-level during the calculation
of said second value in said computer; and a logic circuit for issuing an
interrupt prohibit signal upon receiving output signals of a low-level
from said first and second terminals of said interruption mask and for
issuing an interrupt request signal upon receiving an output signal of a
high-level from said first register and an output signal of a high-level
from said first terminal of said mask during the calculation of said
second value for causing said first value to be calculated in response to
said interrupt request signal.
11. A method for controlling a combustion engine having an output shaft
driven by mechanical energy converted from heat energy caused by the
combustion of an air-fuel mixture, said engine including first and second
control means for controlling the combustion of said air-fuel mixture in
accordance with changes in a condition of said engine, said method
comprising the steps of:
a. generating an electrical signal in the form of a binary number, the
signal indicating a condition of said engine as of a selected instant in
time during operation of said engine;
b. generating a synchronized pulse as part of a pulse train synchronized
with and in response to the rotational speed of said output shaft;
c. generating at least one clock pulse in a predetermined time interval;
d. sequentially calculating first and second values corresponding to
respective settings of said first and second control means by a computer
programmed to calculate said first and second values from a first function
describing a desired relationship between the condition of said engine and
the setting of said first control means and from a second function
describing another desired relationship between the condition of said
engine and the setting of said second control means, the calculations of
said first and second values being respectively performed using said
binary number electrical signal in accordance with said synchronized pulse
and said clock pulse such that the calculation of said first value is
conducted first by said computer in response to receipt of said
synchronized pulse even during the calculation of said second value, and
the rest of the calculation of said second value is subsequently conducted
after completion of the calculation of said first value;
e. converting said first and second calculated values into the settings of
said first and second control means; and
f. continuously repeating the above sequence of steps for controlling the
combustion of the air-fuel mixture in response to any changes in said
binary number electrical signal.
12. A method for controlling a combustion engine as claimed in claim 11,
wherein said first control means includes means for controlling the amount
of air-fuel mixture metered into said engine and means for controlling the
spark-ignition timing of said engine, and wherein the step of generating a
binary number electrical signal indicative of a condition of said engine
includes the step of generating a binary number electrical signal
indicating the rotational speed of said output shaft during the operation
of said engine.
13. A method for controlling a combustion engine as claimed in claim 11,
wherein said second control means includes means for recirculating exhaust
gases caused by the combustion of air-fuel mixture into said engine and
the step of generating a binary number electrical signal indicative of a
condition of said engine further includes the step of generating a binary
number electrical signal indicating changes of in the coolant temperature
of said engine.
14. A method for controlling a combustion engine as claimed in claim 11,
wherein the step of calculating first and second values corresponding to
respective settings of said first and second control means further
includes the step of calculating a third value to sequentially compensate
said first and second calculated values, said computer being further
programmed to calculate said third value from a third function describing
a desired relationship between the condition of said engine and said first
and second calculated values.
15. In an electrical control apparatus for a combustion engine having an
output shaft driven by mechanical energy converted from heat energy caused
by the combustion of an air-fuel mixture, said engine including first
control means for controlling either the amount of air-fuel mixture
metered into said engine and/or the spark-ignition timing of said engine
and second control means for controlling the amount of exhaust gases
recirculated from an exhaust pipe into said engine, said control apparatus
including:
a first electrical circuit for generating an electrical signal in the form
of a binary number, the signal indicating a condition of said engine as of
a selected instant in time during the operation of said engine;
a digital computer for sequentially calculating first and second values
corresponding to respective settings of said first and second control
means by using said binary number electrical signal, said computer being
programmed to calculate said first and second values from a first function
describing a desired relationship between the condition of said engine and
the setting of said first control means and from a second function
describing another desired relationship between the condition of said
engine and the setting of said second control means; and
a second electrical circuit coupled between said digital computer and said
first and second control means for converting said first and second
calculated values into the settings of said first and second control
means;
the improvement comprising:
a detector for generating output pulses at a frequency proportional to the
rotational speed of said output shaft to initiate the calculation of said
first value in said computer;
a clock circuit for generating clock pulses at a predetermined frequency to
initiate the calculation of said second value in said computer, the
frequency of said clock pulses being substantially lower than that of said
output pulses from said detector during the idling of said engine; and
an interrupt controller for issuing an interrupt request signal therefrom
upon receiving one of said output pulses from said detector during the
calculation of said second value to prohibit the calculation of said
second value in said computer and to simultaneously initiate the
calculation of said first value in said computer, the remainder of the
prohibited calculation being executed in said computer after completion of
the calculation of said first value, said interrupt controller issuing an
interrupt prohibit signal therefrom during the calculation of said first
value to continue the calculation of said first value in said computer.
16. The improvement as claimed in claim 15, wherein said interrupt
controller comprises:
a first register for generating an output signal of a high level upon
receiving one of said output pulses from said detector;
a second register for generating an output signal of a high level upon
receiving one of said clock pulses;
an interruption mask for generating at its first and second terminals
output signals of a low level during the calculation of said first value
in said computer and generating at its first terminal an output signal of
a high level and at its second terminal an output signal of a low level
during the calculation of said second value in said computer; and
a logic circuit for issuing an interrupt request signal upon receiving an
output signal of a high level from said first register and an output
signal of a high level from the first terminal of said mask during the
calculation of said second value to prohibit the calculation of said
second value and simultaneously initiate the calculation of said first
value, said logic circuit issuing an interrupt prohibit signal upon
receiving output signals of a low level from the first and second
terminals of said interruption mask to continue the calculation of said
first value.
17. The improvement as claimed in claim 15, wherein said clock circuit
comprises a frequency divider for converting a timing pulse issued from
said computer into at least one clock pulse with a predetermined
frequency, the frequency of said clock pulses being substantially lower
than that of said output pulses from said detector.
18. The improvement as claimed in claim 15, wherein said computer includes
means for repetitively calculating a third value to sequentially
compensate said first and second calculated values by using said binary
number electrical signal, said computer being further programmed to
calculate said third value from a third function describing a desired
relationship between the condition of said engine and said first and
second calculated values, and wherein said clock circuit further generates
second clock pulses at a predetermined frequency to initiate the
calculation of said third value in said computer, the frequency of said
second clock pulses being lower than that of the first-named clock pulses;
said interrupt controller further providing an interrupt request signal
upon receiving one of said output signals from said detector during the
calculation of said third value to prohibit the calculation of said third
value in said computer, the remainder of the prohibited calculation being
executed in said computer after completion of the calculations of said
first and second values.
19. The improvement as claimed in claim 18, wherein said clock circuit
comprises a frequency divider for converting a timing pulse issued from
said computer into at least first and second clock pulses to execute the
respective calculations of said second and third values in said computer,
the frequency of said first clock pulses being higher than that of said
second clock pulses.
20. A method for controlling a combustion engine having an output shaft
driven by mechanical energy converted from heat energy caused by the
combustion of an air-fuel mixture, said engine including first control
means for controlling the amount of air-fuel mixture metered into said
engine and/or the spark-ignition timing of said engine and second control
means for controlling the amount of exhaust gases recirculated from an
exhaust pipe into said engine, said method comprising the steps of:
a. generating an electrical signal in the form of a binary number, said
signal indicating a condition of said engine as of a selected instant in
time during operation of said engine;
b. generating output pulses at a frequency proportional to the rotational
speed of said output shaft to initiate the calculation of a first value;
c. generating clock pulses at a predetermined frequency, the frequency of
said clock pulses being lower than that of said output pulses;
d. sequentially calculating first and second values corresponding to
respective settings of said first and second control means by a computer
programmed to calculate said first and second values from a first function
describing a desired relationship between the condition of said engine and
the setting of said first control means and from a second function
describing another desired relationship between the condition of said
engine and the setting of said second control means, each calculation of
the first and second values being executed by using said binary number
electrical signal in response to said output pulses and said clock pulses,
respectively;
e. issuing an interrupt request signal in response to one of said output
pulses during the calculation of said second value in said computer to
prohibit the calculation of said second value in said computer and
simultaneously initiate the calculation of said first value in said
computer, the remainder of the prohibited calculation being executed in
said computer after completion of the calculation of said first value;
f. issuing an interrupt prohibit signal during the calculation of said
first value to continue the calculation of said first value in said
computer;
g. converting said first and second calculated values into the settings of
said first and second control means; and
h. continuously repeating the above sequence of steps for controlling the
combustion of the air-fuel mixture in response to any changes in said
binary number electrical signal. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
The present invention relates to an electrical control method and apparatus
for a combustion engine, and more particularly to an improvement in a
method and apparatus for controlling the combustion of the air-fuel
mixture in an internal combustion engine in which a digital computer is
employed to control the amount of air-fuel mixture metered into the
combustion chamber of the engine, the spark-ignition timing of the
air-fuel mixture, the recirculation of exhaust gases into the combustion
chamber, and the like, in accordance with changes in the operating
conditions of the engine.
In a conventional method and apparatus for controlling the combustion of
the air-fuel mixture in an engine of this kind, such as for instance,
disclosed in U.S. Pat. No. 3,969,614 by David F. Moyer et al. issued on
July 13, 1976, a digital computer is employed to calculate values
corresponding to proper settings of the various control devices used to
control the energy conversion functions of the engine. The digital
computer is programmed to repetitively calculate the various values or
settings mathematically from an algebraic function or functions describing
desired relationships between various settings of the control devices and
the sensed condition of the engine. This means that the calculations of
the various values are simultaneously executed on a real-time basis at
short angular intervals of rotation of the engine output shaft. As a
result, the digital computer is required to have a large calculation
capacity so as to complete the calculations of the various values at a
high speed. Thus, such a conventional engine control apparatus and its
digital computer are inevitably complicated in their construction and high
in production cost.
SUMMARY OF THE INVENTION
It is, therefore, a primary object of the present invention to provide an
improved control method and apparatus for a combustion engine in which a
digital computer initially calculates a first value corresponding to
proper settings of first control means used to control the amount of
air-fuel mixture metered into the internal combustion engine,
spark-ignition timing, and the like, at angular intervals of rotation of
the engine output shaft, and subsequently calculates a second value
corresponding to proper settings of second control means used to control
exhaust gas recirculation in the internal combustion engine, and the like,
after completion of the calculation of the first value, to thereby reduce
the production cost of the digital computer.
Accordingly, in the practice of the present invention, there is provided
a method for controlling a combustion engine having an output shaft driven
by mechanical energy converted from heat energy caused by the combustion
an air-fuel mixture, the engine including first and second control means
for controlling the combustion of the air-fuel mixture in accordance with
changes in a condition of the engine, the method comprising the steps of:
generating an electrical signal in the form of a binary number, the signal
indicating the condition of the engine as of a selected instant in time
during operation of the engine;
generating a pulse train synchronized with the rotational speed of the
output shaft;
generating at least one clock pulse in a predetermined time interval;
calculating first and second values corresponding to respective settings of
the first and second control means in a time sequence by a computer
programmed to calculate the first and second values from a first function
describing a desired relationship between the condition of the engine and
the setting of the first control means and from a second function
describing another desired relationship between the condition of the
engine and the setting of the second control means, the calculations of
the first and second values being respectively performed using the binary
number electrical signal in accordance with one of said synchronized
pulses and the clock pulse such that the calculation of the first value is
initially conducted in response to the synchronized pulse during the
calculation of the second value and the remaining calculation of the
second value is subsequently conducted after completion of the calculation
of the first value;
converting the first and second calculated values into the setting of the
first and second control means; and thereafter
continuously repeating the above sequence of steps for controlling the
combustion of the air-fuel mixture in response to changes in the binary
number electrical signal.
BRIEF DESCRIPTION OF THE DRAWINGS
Additional objects and advantages of the present invention will be more
readily apparent from the following detailed description of preferred
embodiments thereof when taken together with the accompanying drawings in
which:
FIG. 1 is a schematic block diagram of an electrical control system for an
internal combustion engine in accordance with the present invention;
FIG. 2 is a circuit diagram of an embodiment of the rotation speed detector
illustrated in block form in FIG. 1;
FIG. 3 is a circuit diagram of an embodiment of the clock circuit
illustrated in block form in FIG. 1;
FIG. 4 is a circuit diagram of an embodiment of the interrupt controller
illustrated in block form in FIG. 1; and
FIG. 5 is a flow diagram illustrative of the operation of the digital
computer in relation to the interrupt controller of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the accompanying drawings, in particular to FIG. 1, there
is illustrated a schematic block diagram of an electrical control system
for an internal combustion engine according to the present invention, in
which settings of ignition timing, fuel injection and exhaust gas
recirculation are controlled by a digital computer in a time sharing
method in response to various conditions of the engine sensed during its
operation, thereby to maximize energy conversion efficiency, fuel economy
and torque and to minimize the emission from the engine of noxious
pollutants. In the internal combustion engine, upon opening of an intake
valve V.sub.1, the air flowing through an air cleaner 28, an induction
passage 30a and an intake manifold 30b is mixed with fuel injected from an
electrically controlled fuel injector 19 and, in turn, the air-fuel
mixture is introduced into a combustion chamber of the engine. The
air-fuel mixture is compressed by a piston P.sub.1 in an upward stroke
within a cylinder C.sub.1 and is ignited by a spark produced by a spark
plug 17a in the combustion chamber to rotate a crank shaft or output shaft
21 connected to the piston P.sub.1. Upon opening of an exhaust valve
V.sub.2, the exhaust gases are discharged into an exhaust manifold 31 and
partially recirculated into the induction passage 30a by way of a water
cooler 32 and an exhaust gas recirculation or EGR valve 24. The fuel from
the fuel injector 19 is delivered from a fuel pump 25 connected to a fuel
tank 34 and is controlled in pressure by a fuel pressure regulator 33. An
air valve 26 is arranged to associate with the fuel injector 19 to supply
the air from upstream to downstream of a throttle valve 29 when the
throttle valve 29 is closed. The spark plug 17a receives high voltage
electric energy from a distributor 16 connected to an ignition coil 14 at
appropriate time intervals. Although the engine shows only one combustion
chamber formed by the cylinder C.sub.1 and the piston P.sub.1, it should
be understood that the engine control system is designed for use on a
six-cylinder engine, including a total of six cylinders, six intake
valves, six exhaust valves and six pistons, six spark plugs and six fuel
injectors. Further, it should be recognized that in a case of the
reciprocating engine, the spark plugs 17a and the fuel injectors 19 are
activated at least once per two rotations of the crank shaft 21, while the
EGR valve 24 is opened occasionally. In the case of a rotary engine, the
spark plugs and the fuel injectors are activated at least once for each
rotation of the rotor, while the EGR valve is also opened occasionally.
The engine control system comprises a digital computer 1 having a
microprocessor and a memory and for calculating repetitively first and
second values corresponding to respective optimum settings or timing of
actuation of the ignition coil 14, the fuel injectors 19 and the EGR valve
24 to control the combustion of the air-fuel mixture in accordance with
various conditions of the engine. The computer 1 is programmed to
mathematically calculate the above-mentioned values from a first algebraic
function describing a desired relationship between the conditions of the
engine and the operation or actuation of the ignition coil 14 and the fuel
injectors 19 and from a second algebraic function describing another
desired relationship between the conditions of the engine and the setting
of the EGR valve 24. The desired algebraic relationships are determined
experimentally. At every instant during the operation of the engine, and
over its entire range of operation, there exist optimum settings and
conditions of operation for the above-mentioned devices. The definition of
what is optimum is not fixed, but rather depends upon the use to which the
engine is to be put and its state of operation at a particular instant.
The calculations in the computer 1 are performed in a time sharing method
in response to a signal from an interrupt controller 3, as described later
in detail. The interrupt controller 3 is controlled by instruction words
from the computer 1 in such a manner that the priority of the calculations
is determined in accordance with respective signals applied to the
computer 1 from a rotation speed detector 6 and a clock circuit 4.
The rotation speed detector 6 includes a magnetic pick up transducer 5 to
produce angular pulses in response to the rotational speed of the crank
shaft 21. The transducer 5 preferably comprises an electrical coil which
generates an alternating voltage across its terminals as a result of
changes in magnetic flux in its magnetic circuit. These flux changes are
produced by a notched member 40 connected to the crank shaft 21 for
rotation therewith. The notched member 40, for example, has six notches
equally spaced to generate three angular pulses during one rotation of the
crank shaft 21. Each pulse generated from the transducer 5 is divided by a
third in frequency in the rotation speed detector 6. The pulses from the
transducer 5 in the form of a binary number are transferred to a
bidirectional data bus 2 for the computer 1 through the rotation speed
detector 6. The clock circuit 4 is designed to produce first, second and
third clock pulses at the time intervals of 100 msec, 1 sec and 10 sec
from timing pulses issued from the computer 1.
Various sensors which are used to detect the conditions of the engine will
now be described in detail. An analog multiplexer 7 receives electric
signals from an air flow meter 8, a first vacuum sensor 9, a second vacuum
sensor 10 and a coolant temperature sensor 11. The various input signals
are selected in the multiplexer 7 in accordance with requests from the
computer 1 and are converted, one-by-one, by an analog-to-digital
converter 12 into digital form. The converted digital signals are
transferred to the computer 1 by way of the data bus 2. The air flow meter
8 is provided in the induction passage 30a to detect the amount of air
flow from the air cleaner 28 and temperature of the air. The first vacuum
sensor 9 is disposed within the induction passage 30a slightly upstream of
the throttle valve 29, while the second vacuum sensor 10 is also disposed
within the induction passage 30a slightly down stream of the throttle
valve 29. The vacuum sensors 9 and 10 detect negative pressures on the
upstream and downstream sides of the throttle valve 29, respectively. The
coolant temperature sensor 11 is provided in the engine cooling system to
sense the coolant temperature of the engine. The computer 1 directly
receives signals that are responsive to the activation and deactivation of
the air flow meter 8 and the starter motor 35 of the vehicle, and
simultaneously receives first and second signals from a throttle position
sensor 37 which are generated in the throttle position sensor 37 to detect
the occurrence of the idle position and the 50.degree.-open angular
position of the throttle valve 29.
A spark timing logic circuit 13 is connected to the computer 1 by way of
the data bus 2 to preset therein digital values transferred from the
computer 1. The logic circuit 13 is also triggered by angular pulses from
the transducer 5 to generate ignition timing control pulses whose width
and phase are varied in accordance with the preset digital values in the
logic circuit 13 to control energization of the ignition coil 14. The
output signals from the logic circuit 13 are amplified by an ignitor 15
and are then applied to the ignition coil 14.
A fuel injection control logic circuit 18 is connected to the computer 1 by
way of the data bus 2 to receive digital values transferred from the
computer 1 so as to periodically generate a control pulse for each
rotation of the crank shaft 21. The pulse width of the control pulses are
varied in proportion to the digital values received from the computer and
the pulses are then amplified by an injector drive circuit 22. Thus, the
on-off timing of the fuel injectors 19 are controlled by the amplified
control pulses from the drive circuit 22.
A latch circuit 23 is also connected to the computer 1 by way of the data
bus 2 to receive digital values transferred from the computer 1. The latch
circuit 23 generates and latches control pulses in accordance with the
digital values and applies them to a power amplifier 27 in response to
signals transferred from the computer 1. The latched control pulses are
then amplified by a power amplifier 27 and are then applied to the EGR
valve 24, the fuel pump 25 and the air valve 26 so that the on-off timing
of these devices are controlled in accordance with the values calculated
in the computer 1.
An interface controller 39 is provided to control operation of an interface
circuit, including the rotation speed detector 6, the analog multiplexer
7, the analog-to-digital converter 12, the spark timing logic circuit 13,
the fuel injection control logic circuit 18 and the latch circuit 23, in
accordance with calculations of the algebraic functions in the computer 1.
The operation of the interface controller 39 is controlled by a control
signal and the calculated values transferred from the computer 1 through a
control bus 2a and the data bus 2.
In the practice of the present invention, an RCA CDP1801D COSMAC
MICROPROCESSOR, as reported in a USER MANUAL for the CDP1801D COSMAC
MICROPROCESSOR published by RCA, is preferred for use as the
microprocessor of the computer 1, and a programmable read-only memory
(PROM) and a random access memory (RAM) have been used as the memory of
the computer 1. In the following description, the particular programming
process will be understood from the "MPM-102 Program Development Guide"
for the COSMAC MICROPROCESSOR.
Hereinafter, a preferred embodiment of the rotation speed detector 6 will
be described in detail with reference to FIG. 2. In the embodiment, the
rotation speed detector 6 comprises a low pass filter 601b for filtering
angular pulses generated from the magnetic pickup transducer 5 and a
comparator 601 for comparing the angular pulses filtered by the low pass
filter 601b with a reference signal from a voltage divider including
resistors 601a to generate output signals applied to a Schmitt trigger
circuit 605, which may be, for example, type CD4093 manufactured by RCA.
The Schmitt trigger circuit 605 sharply reshapes the form of output
signals of the comparator 601. The reshaped output signals are applied via
line 621 to a frequency divider including first and second D flip-flops
610 and 611. The frequency divider divides each of the reshaped output
signals on line 621 by one third in frequency and applies the divided
signals as synchronized pulses INT0 (i.e. synchronized with the rotation
of crank shaft 21) to an inverter 311a of the interrupt controller 3
through a line 300, as shown in FIG. 4. The Schmitt trigger circuit 605
also applies the reshaped output signals on line 621 to a control circuit
620. The control circuit 620 functions to apply the reshaped output
signals on line 621 from the Schmitt trigger circuit 605 to a counting
circuit 630 in accordance with data output signals OUT0 to OUT7 and N code
output signals N0 to N3 issued from the microprocessor of the computer 1.
The counting circuit 630 comprises a sixteen-bit binary counter for
counting each period of the reshaped output signals on line 621 and a
register for receiving the counted results from the binary counter and
transferring them to the computer 1 as input signals IN0 to IN7, which
represent the instantaneous rotational speed of the crank shaft 21. By way
of example, the output from the sixteen-bit binary counter assume the
following values in relation to the engine rotational speed.
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SPEED OF COUNTED RESULT IN
ENGINE ROTATION HEXADECIMAL NOTATION
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300 r.p.m. 8235
600 411A
6000 0682
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From the above relationships it may be appreciated that the outputs counted
results of the binary counter are inversely proportional to the speed of
engine rotation.
In operation of the rotation speed detector 6 in relation to the
programming process in the computer 1, the rotation speed detector 6 is
selected from the interface circuit by an instruction word "OUT 5, #10"
issued from the computer 1 to the control circuit 620 so that the period
of each reshaped output signal on line 621 will be counted by the binary
counter of the counting circuit 630. The counted results of the binary
counter are transferred to the register in the counting circuit 630 by an
instruction word "OUT 0, 0" issued from the computer 1. Then, the
low-order eight bits of the counted results are read into an address of
the memory defined by a register RB in the computer 1 by means of an
instruction word "INP 1" issued from the computer 1. For instance, when
the engine rotates at 6000 r.p.m., the low-order eight bits 82 of 0682 in
hexadecimal notation will be read into the computer 1. The high-order
eight bits of the counted results are read into another address of the
memory by means of an instruction word "INP 2" issued from the computer 1.
For instance, when the engine rotates at 6000 r.p.m., the high-order eight
bits 06 of 0682 in hexadecimal notation will be read into the computer 1.
Thus, it should be understood that each period of the reshaped output
signals on line 621 from the Schmitt trigger circuit 605 will be counted
in the counting circuit 630 and read into the specific addresses of the
memory in the computer 1 by means of the respective instruction words
transferred to the control circuit 620 from the computer 1.
In FIG. 3, the clock circuit 4 comprises an eight-bit binary counter 410,
which may comprise, for example, a C-MOS IC type CD4040 manufactured by
RCA, which functions to count a timing pulse TPA of 250 (KHz) issued from
the computer 1 and to apply the counted results to a frequency divider
including AND-gates 416 to 418, a D flip-flop 415, inverters 419, 421 and
422 and an AND-gate 420. The frequency divider functions to frequency
divide each counted result of the binary counter 410 by 250 to generate
clock pulses of 1 KHz. at the output terminal Q of the D flip-flop 415. A
decade counter 411 functions to frequency divide each clock pulse of 1
KHz. by ten. Subsequently, each divided clock pulse of 100 Hz. is further
frequency divided by ten by a decade counter 412. The 10 Hz. divided
pulses are applied as first clock pulses INT1 to an inverter 312a of the
interrupt controller 3 (see FIG. 4) through an inverter and line 301, and
are also applied to a decade counter 413. The decade counter 413 functions
to frequency divide each first clock pulse INT1 by ten and to apply the 1
Hz. divided clock pulses as second clock pulses INT2 to an inverter 313a
of the interrupt controller 3 (FIG. 4) through an inverter and line 302. A
further decade counter 414 receives each second clock pulse INT2 of 1 Hz.
from the decade counter 413 and frequency divides it again by ten. The 0.1
Hz. divided second clock pulses are applied as third clock pulses INT3 to
an inverter 314a of the interrupt controller 3 (FIG. 4) through an
inverter and line 303. The decade counters 411 to 414 may preferably
comprise C-MOS ICs type CD4017 manufactured by RCA. Thus, the clock pulses
INT1 to INT3 of 100 msec., 1 sec. and 10 sec. are respectively obtained by
dividing the clock pulses of 1 msec. from the D flip-flop 415 of the
frequency divider.
A preferred embodiment of the interrupt controller 3 will be described
below in detail with reference to FIGS. 4 and 5. The interrupt controller
3 comprises four interrupt request registers or D flip-flops 311 to 314,
and a multi-level interruption mask 310 using a parallel-in-parallel out
register. The first interrupt request register 311 receives at its input
terminal CL the synchronized pulse INT0 through the inverter 311a to
generate high-level signals at its output terminal Q. The second, third
and fourth interrupt request registers 312, 313 and 314 respectively
receive at their input terminals CL the first, second and third clock
pulses INT1, INT2 and INT3 through the inverters 312a, 313a and 314a to
generate high-level signals at their output terminals Q. The interrupt
request registers 311 to 314 are respectively reset by reset signals
applied to their reset terminals R from four AND-gates 391a to 391d to
generate low-level signals at their output terminals Q.
The multi-level interruption mask 310 receives at its input terminals
D.sub.1 to D.sub.4 signals OUT0 to OUT3 responsive to an instruction word
"OUT 6, #OM" (M=0, 1, 2 . . . , F in hexadecimal notation) issued from the
computer 1 and simultaneously receives at its terminal CL a set signal
responsive to the instruction word "OUT 6, #OM" transferred from the
computer 1 through a NAND-gate 310e to generate high or low level control
signals at its output terminals Q.sub.1 to Q.sub.4. The interruption mask
310 is reset upon receiving at its reset terminal R a reset signal issued
from the computer 1 to generate high-level control signals at its output
terminals Q.sub.1 to Q.sub.4.
If low-level control signals appear at the terminals Q.sub.1 to Q.sub.4 of
the interruption mask 310, four AND-gates 361 to 364 cannot be turned on
in response to signals from the registers 311 to 314. In this case, output
signals of the AND-gates 361 to 364 are maintained at a low-level so that
a NOR-gate 365 will issue a high-level signal which is applied as an
interrupt prohibit signal to the computer 1 through line 305.
If high and low level signals respectively appear at the terminals Q.sub.1
and Q.sub.2 and the terminals Q.sub.3 and Q.sub.4 of the mask 310, the
AND-gates 361 and 362 can be turned on in response to signals from the
registers 311 and 312, while the AND-gates 363 and 364 cannot be turned on
in response to signals from the registers 313 and 314. In this instance,
the AND-gates 361 and 362 issue high-level signals upon receiving
high-level signals from the registers 311 and 312 and then the NOR-gate
365 issues a low-level signal which is applied as an interrupt request
signal INT to the computer 1 through the line 305. (This corresponds to an
interrupt description or INTRDS step shown at 100 in FIG. 5.)
The interrupt controller 3 further comprises a BCD-to-decimal decoder 320
to control the AND-gates 391a to 391d, the NAND-gate 310e and an AND-gate
322.
Assume, for example, that the interrupt prohibit signal from the NOR-gate
365 is transferred to the computer 1 during a calculation in the computer
1 responsive to a synchronized pulse INT0. The computer 1 will then
continue its calculation responsive to the synchronized pulse INT0.
If the interrupt request signal INT from the NOR-gate 365 is transferred to
the computer 1 during a calculation in the computer 1 responsive to the
second clock pulse INT2 from the clock circuit 4, the computer 1
discontinues the calculation responsive to the second clock pulse INT2 to
store the calculated data based thereon in | | |
