[0001] The present invention relates to a system for identifying the strokes of an internal
combustion engine.
[0002] Internal combustion engine electronic ignition systems are known to feature an electronic
control system for determining spark advance on the basis of signals received from
various sensors (principally engine speed and stroke sensors). If said systems are
also electronic injection types, on the basis of further signals (intake air pressure
and temperature), the control system determines, for example, air density inside the
manifold and engine speed, and calculates, via interpolation on respective memorised
maps, the stroke of the engine and fuel injection time to the injectors.
[0003] Said electronic ignition system employs angle references fitted on to the drive and
distributor shafts to enable the control system to identify the stroke of each cylinder
on the engine (intake, compression, expansion, exhaust).
[0004] Current stroke identification systems employ angle references on the drive shaft,
equal in number to the cylinders on the engine, and consisting, for example, of equally
spaced projecting teeth. Said references are detected by a first sensor arranged facing
them and which, every two references, and via the control system, enables an ignition
command. Said system also requires a further stroke sensor for detecting the angle
of an auxiliary shaft turning at half the speed of, but in strict time with, the drive
shaft, and consisting, for example, of the camshaft or similar.
[0005] In the event of a fault on the stroke sensor, the electronic ignition system becomes
totally ineffective, thus resulting in stoppage of the engine, which can only be restarted
by repairing the stroke sensor.
[0006] The aim of the present invention is to provide an internal combustion engine stroke
identification system designed to overcome the above drawback, i.e. which enables
the engine to be operated even in the event of a fault on the stroke sensor.
[0007] An internal combustion engine stroke identification system, comprising :
a fuel supply member;
an electronic ignition system featuring a distributor; first sensor means for detecting
predetermined angular positions of a drive shaft;
second sensor means for detecting predetermined angular positions of the shaft of
said distributor;
means for defining a sequence of signals from said first and second sensor means;
and
means for memorising said sequence of said signals is known from EP-A-204 221.
[0008] According to the present invention, such a stroke identification system is provided
with
means for comparing said sequence of said signals in the current cycle with that of
a previous cycle;
means for determining non-reception of a said signal from said second sensor means
in accordance with said sequence in the previous cycle;
means for updating said sequence in the current cycle according to said sequence in
the previous cycle, in the event of non-reception of said signal from said second
sensor means; and
processing means for receiving signals corresponding to said updated sequence of said
signals from said first and second sensor means; identifying the strokes of said engine;
and enabling said electronic ignition system.
[0009] A preferred, non-limiting embodiment of the present invention will be described by
way of example with reference to the accompanying drawings, in which:
Fig.1 shows a schematic view of an electronic injection system for an internal combustion
engine featuring the engine stroke identification system according to the present
invention;
Fig.2 shows a schematic view of certain components on the Fig.1 system;
Fig.3 shows an operating block diagram of the system according to the present invention;
Fig.4 shows a schematic view of a number of signals on the system according to the
present invention.
[0010] The system according to the present invention may be used on engines featuring an
electronic ignition system with or without an electronic injection system. In the
example shown, the engine also features an electronic injection system, i.e. a certain
type of fuel supply, but, as will become apparent in the following description, the
system according to the present invention also applies in the case of fuel supplied
by an ordinary carburetor, providing, of course, provision is made for an electronic
ignition system.
[0011] Fig.1 shows a schematic view of an electronic injection system for an internal combustion
engine 101, conveniently a four-cylinder engine, shown partially in cross section.
Said system comprises an electronic control system 102 in turn comprising, in substantially
known manner, a microprocessor 103 and memories containing maps relative to various
operating conditions of engine 101. Control system 102 also comprises a counter 104;
an updatable memory register 105; and an addressable-cell memory register 106.
[0012] Control system 102 receives signals from:
a sensor 107 for detecting the speed of engine 101 and located opposite a pulley 108
fitted on to a drive shaft 111;
a sensor 112 for detecting the stroke of engine 101 and located inside a distributor
113;
a sensor 114 for detecting the absolute pressure in the intake manifold 115 of engine
101;
a sensor 116 for detecting the air temperature inside manifold 115;
a sensor 117 for detecting the water temperature inside the cooling jacket of engine
101; and
a sensor 118 consisting substantially of a potentiometer, for detecting the setting
of a throttle valve 121 located inside intake manifold 115 and controlled by the accelerator
pedal 122. An extra air supply valve 123 is provided parallel to throttle valve 121.
[0013] Control system 102 is grounded and connected to a supply battery 124.
[0014] On the basis of signals supplied to control system 102, engine speed and air density
are used for determining fuel supply as a function of the required mixture strength.
Control system 102 controls the opening time of electroinjectors 127 located inside
manifold 115, close to the intake valve of each cylinder, for controlling fuel supply
to the various cylinders on engine 101, and controls fuel injection timing for commencing
fuel supply in relation to the stroke (intake, compression, expansion, exhaust) of
engine 101. Electroinjector 127 is supplied with fuel via a pressure regulator 128
sensitive to the pressure inside intake manifold 115, and having a fuel inlet conduit
131 connected to a pump (not shown), and a return conduit 132 to a tank (not shown).
Finally, control system 102 is connected to an ignition pulse control unit 133 connected
to distributor 113.
[0015] With reference to Fig.2, pulley 108 presents four projecting teeth 134 equally spaced
at 90° intervals, and sensor 107 is arranged facing the passage of teeth 134, at such
an angle as to detect passage, for example, +10° and +100° in advance of the top dead
center position of each cylinder. Pulley 108 may be fitted so that said angles range
respectively from +20° to +0° and from +110° to +90°, one pair of teeth 134 being
square with the other. The sequence of signals (S) supplied by sensor 107 as drive
shaft 111 rotates is shown in Fig.4a. Again with reference to Fig. 2, sensor 112 is
arranged facing a disc 135 secured angularly to the shaft of distributor 113, and
having two projecting teeth 136 ninety degrees apart. In particular, sensor 112 is
located within the cylinder 3 range of distributor 113, and at such an angle that,
when one tooth 134 is arranged facing speed sensor 107, the first tooth 136 on disc
135 lags 27.5° in relation to the axis of sensor 112. The sequence of signals (C)
supplied by sensor 112 (Fig.4b) for each complete cycle of engine 101 presents a first
signal 55° behind the foregoing signal from sensor 107 and, in the example shown,
135° ahead of the top dead center position of cylinder 3. The second signal supplied
by sensor 112 as the second tooth 136 moves past it is 135° ahead of the top dead
center position of cylinder 4, and 180° behind the first signal from sensor 112, in
that, each complete turn of disc 135 corresponds to two turns of drive shaft 11 and,
consequently, pulley 108. Operation of the system for identifying the strokes of engine
101 is described in the aforementioned EP-A-204 221, corresponding to Italian Patent
n.1184958 entitled "Internal combustion engine stroke identification system" filed
by the present Applicant on 4.6.1985, issued on 28.10.1987.
[0016] As already stated, in the event of a fault on stroke sensor 112, the electronic ignition
system becomes totally ineffective and engine 101 stops, and can only be restarted
by repairing sensor 112. As explained in more detail later on, in the event of a fault
developing on sensor 112 during operation of engine 101, the system according to the
present invention enables operation of engine 101 to be continued on the basis of
the operating cycle preceding that in which the fault is developed on sensor 112.
[0017] Operation of the system for identifying the strokes of engine 101 will be described
with reference to Fig.3. As shown in Fig.3, a repeat cycle starting block 170 goes
on to a block 171 for enabling the S and C signal observation channels, and which
goes on to a block 172 relative to an S and C signal identification routine. In the
event of an S signal, block 172 goes on to block 173 and, in the event of a C signal,
to block 174. Block 173 provides for updating counter 104 and memorising the S signal
(Fig.4c), after which it goes on to block 175, which checks whether the signal received
and certified in block 171 conforms with what has been updated on counter 104. For
example (Fig.4c), if counter 104 starts from 0, the signal which should now be received
is a C type. If an S type is received, this indicates non-conformance with counter
104. In the event of conformance with counter 104, block 175 goes on to block 176
and, conversely, to block 177. Block 176 provides for sequentially supplying the ignition
pulses via unit 133 and, in the case of electronic injection systems, for also controlling
fuel supply, after which it goes back to start block 170 for the next cycle. Block
177 checks whether a C signal should have been received and, in the event of a positive
response, goes on to block 178. In the event of a negative response, block 177 goes
on to block 181, which memorises the S signal error, which may be caused, for example,
by a spurious signal.
[0018] Block 178 provides for updating counter 104 as though a C signal had been received,
after which it goes on to block 182 and, from there, to block 176. Block 182 provides
for memorising the C signal error, i.e. the fact that a C signal has not been received.
Block 174 checks the existence of a C signal error and, in the event of a positive
response, goes on to block 183. In the event of a negative response, block 174 goes
on to block 184, which provides for updating counter 104 and memorising the C signal.
In other words, blocks 173 and 184 provide for mapping and memorising the S and C
signal sequence in counter 104, so that block 178 in effect provides for taking and
updating the reference map preceding the C signal error and defined in blocks 173
and 184. In the event of a fault developing on sensor 112 during operation of engine
101, this is therefore allowed to continue operating, thus enabling the user to arrive
at his or her destination. Block 184 goes on to block 185 which, like block 175, determines
whether the incoming signal conforms with the content of counter 104. If it does,
block 185 goes on to block 176 and, if it does not, to block 186.
[0019] Block 183 provides for deleting the C signal error in block 182, and block 186 for
memorising the sequence error. Blocks 181, 183 and 186 go on to a resynchronizing
routine which, on the basis of a predetermined number of S and C signals, identifies
the various strokes of the cylinders. Said routine is shown in Fig.3 of EP-A-204 221.
Blocks 181, 183 and 186 therefore go back to the start block shown in Fig.3 of EP-A-204
221.
[0020] In the example shown of a four-cylinder engine, a number of teeth 134 equal to the
number of cylinders, two teeth 136, a predetermined angular position of sensors 107
and 112, and a rotation speed of disc 135 equal to half that of pulley 108, counter
104 can count from 0 to 9. The time sequence of the output value from counter 104
is shown in Fig.4c. Counter 104 is incremented one unit for each signal received from
sensors 107 and 112, and, when the maximum value (9) is reached, the next signal from
sensor 107 sends the counter back to 0 in that the same signal cycle from sensors
107 and 112 and the same stroke cycle of engine 101 is repeated. The output value
of 0 to 9 on counter 104 therefore identifies the strokes of engine 101, as described
in EP-A- 204 220, corresponding to Italian Patent n.1184957 entitled "Startup fuel
supply system for an internal combustion engine comprising an electronic injection
system" filed on 4.6.1985 by the present Applicant, issued on 28.10.1987.
[0021] Once the strokes of engine 101 have been identified, block 176 provides for sequentially
supplying the ignition pulses via unit 133, while distribution to the various cylinders
is performed by distributor 113.
[0022] The advantages of the present invention will be clear from the foregoing description.
[0023] In particular, it provides for overcoming malfunctioning of the stroke sensor during
normal operation of the engine. In the absence of information relative to the engine
stroke, this is ignored by the system according to the present invention, which continues
operating, unlike known systems which suspend all outward activity and remain locked
in a predetermined sync search cycle.
[0024] In other words, the system according to the present invention assumes said information
to be already verified, and therefore controls engine 101 on the basis of the map
memorised prior to development of the fault on sensor 112. The system, however, keeps
a close watch on operation of sensor 112 and, when this is restored, is once more
synchronized with engine 101.
[0025] To those skilled in the art it will be clear that changes may be made to the identification
system as described and illustrated herein without, however, departing from the scope
of the present invention as defined in the appended claims.
1. A system for identifying the strokes of an internal combustion engine (101), comprising
:
a fuel supply member;
an electronic ignition system featuring a distributor (113);
first sensor means (107) for detecting predetermined angular positions of a drive
shaft (111);
second sensor means (112) for detecting predetermined angular positions of the shaft
of said distributor (113);
means (104) for defining a sequence of signals (S, C) from said first (107) and second
(112) sensor means, respectively ; means (173) for memorising said sequence of said
signals (S, C);
characterized by the fact that it comprises :
means (174, 175, 177, 185) for comparing said sequence of said signals (S, C) in the
current cycle with that of a previous cycle;
means (177) for determining non-reception of a said signal (C) from said second sensor
means (112) in accordance with said sequence in the previous cycle;
means (178) for updating said sequence in the current cycle according to said sequence
in the previous cycle, in the event of non-reception of said signal (C) from said
second sensor means (112); and
processing means (102) for receiving signals corresponding to said updated sequence
of said signals (S, C) from said first (107) and second (112) sensor means; identifying
the strokes of said engine (101); and enabling said electronic ignition system.
2. A system as claimed in Claim 1, characterised by the fact that said means for defining
said sequence of said signals (S, C) comprise a counter (104) incremented one unit
for each said signal (S or C) from said first (107) and second (112) sensor means
received by said processing means (102), and designed, for each increment, to supply
said processing means (102) with a corresponding signal for defining said sequence
of said signals (S, C) from said first (107) and second (112) sensor means; the content
of said counter (104) being reset by each repetition of the cycle of said signals
(S, C) from said first (107) and second (112) sensor means.
3. A system as claimed in Claim 1 and/or 2, characterised by the fact that it comprises
means (182, 183, 186) for memorising a possible error in the current cycle sequence
of said signals (S, C) from said first (107) and second (112) sensor means as compared
with the previous cycle sequence.
4. A system as claimed in any one of the previous Claims, characterised by the fact that
it is applied to a timed, sequential electronic injection system of an internal combustion
engine.
1. Identifikationssystem für die Takte einer Verbrennungskraftmaschine (101) mit
einem Kraftstoffversorgungsteil;
einem elektronischen Zündsystem mit einem Verteiler (113);
einem ersten Sensor (107) zum Erfassen von vorbestimmten Winkelstellungen einer Antriebswelle
(111);
einem zweiten Sensor (112) zum Erfassen von vorbestimmten Winkelstellungen der Welle
des Verteilers (113);
Mitteln (104) zum Definieren einer Abfolge von Signalen (S, C) von dem ersten Sensor
(107) bzw. dem zweiten Sensor (112);
Mitteln (173) zum Speichern der Abfolge der Signale (S, C); dadurch gekennzeichnet,
daß es enthält:
Mittel (174, 175, 177, 185) zum Vergleichen der Abfolge der Signale (S, C) des gegenwärtigen
Zyklus mit derjenigen eines vorhergehenden Zyklus;
Mittel (177), um gemäß der Abfolge des vorhergehenden Zyklus das Nicht-Empfangen eines
Signals (C) von dem zweiten Sensor (112) festzustellen;
Mittel (178) zum Aktualisieren der Abfolge des gegenwärtigen Zyklus gemäß der Abfolge
des vorhergehenden Zyklus im Falle des Nicht-Empfangens des Signals (C) von dem zweiten
Sensor (112); und
Verarbeitungsmittel (102) zum Empfangen von Signalen, welche der aktualisierten Abfolge
der Signale (S, C) von dem ersten Sensor (107) und dem zweiten Sensor (112) entsprechen;
Identifizieren der Takte der Maschine (101) und Freigeben des elektronischen Zündsystems.
2. System nach Anspruch 1, dadurch gekennzeichnet, daß die Mittel zum Definieren der
Abfolge der Signale (S, C) einen Zähler (104) enthalten, der für jedes der Signale
(S oder C) von dem ersten Sensor (107) und dem zweiten Sensor (112), das von den Verarbeitungsmitteln
(102) empfangen wird, um eine Einheit weitergeschaltet wird und so ausgelegt ist,
daß er für jedes Weiterschalten die Verarbeitungsmittel (102) mit einem entsprechenden
Signal versorgt, um die Abfolge der Signale (S, C) von dem ersten Sensor (107) und
dem zweiten Sensor (112) zu definieren, wobei der Inhalt des Zählers (104) durch jede
Wiederholung des Zyklus der Signale (S, C) von dem ersten Sensor (107) und dem zweiten
Sensor (112) zurückgesetzt wird.
3. System nach Anspruch 1 und/oder Anspruch 2, dadurch gekennzeichnet, daß es Mittel
(182, 183, 186) zum Speichern eines möglichen Fehlers in der Abfolge der Signale (S,
C) von dem ersten Sensor (107) und dem zweiten Sensor (112) des gegenwärtigen Zyklus
im Vergleich mit der Abfolge des vorhergehenden Zyklus enthält.
4. System nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß es bei
einem zeitgesteuerten, sequentiellen elektronischen Einspritzsystem einer Verbrennungskraftmaschine
verwendet wird.
1. Un système pour identifier les courses d'un moteur à combustion interne (101) comprenant:
un élément d'alimentation decarburant;
un système d'allumage électronique comportant un distributeur (113);
un premier moyen capteur (107) pour détecter des positions angulaires prédéterminées
d'un arbre d'entraînement (111) ;
un deuxième moyen capteur (112) pour détecter des positions angulaires prédéterminées
de l'arbre dudit distributeur (113);
un moyen (104) pour définir une séquence de signaux (S,C) à partir dudit premier moyen
capteur (107) et dudit deuxième moyen capteur (112) respectivement;
un moyen (173) pour mémoriser ladite séquence desdits signaux (S, C) ;
caractérisé en ce qu'il comprend:
des moyens (174, 175, 177, 185) pour comparer ladite séquence desdits signaux (S,
C) dans le cycle courant avec celle d'un cycle précédent;
des moyens (177) pour déterminer la non-réception dudit signal (C) à partir dudit
deuxième moyen capteur (112) conformément à ladite séquence dans le cycle précédent;
des moyens (178) pour mettre à jour ladite séquence dans le cycle courant conformément
à ladite séquence dans le cycle précédent dans le cas de la non-réception dudit signal
(C) à partir dudit deuxième moyen capteur (112); et
des moyens de traitement (102) pour recevoir les signaux correspondant à ladite séquence
mise à jour desdits signaux (S, C) à partir dudit premier moyen capteur (107) et dudit
deuxième moyen capteur (112); pour identifier les courses dudit moteur (101) et valider
ledit système d'allumage électronique.
2. Un système selon la revendication 1, caractérisé en ce que lesdits moyens pour définir
ladite séquence desdits signaux (S, C) comprennent un compteur (104) incrémenté d'une
unité pour chaque dit signal (S ou C) à partir dudit premier moyen capteur (107) et
dudit deuxième moyen capteur (112) reçu par ledit moyen de traitement (102) et conçu
pour chaque incrément, pour alimenter ledit moyen de traitement (102) avec un signal
correspondant pour définir ladite séquence desdits signaux (S, C) à partir dudit premier
moyen capteur (107) et dudit deuxième moyen capteur (112); le contenu dudit compteur
(104) étant réinitialisé par chaque répétition du cycle desdits signaux (S, C) à partir
dudit premier moyen capteur (107) et dudit deuxième moyen capteur (112).
3. Un système selon la revendication 1 et/ou 2, caractérisé en ce qu'il comprend des
moyens (182, 183, 186) pour mémoriser une erreur possible dans la séquence de cycle
courante desdits signaux (S, C) à partir dudit premier moyen capteur (107) et dudit
deuxième moyen capteur (112) comparativement à la séquence de cycle précédente.
4. Un système selon l'une quelconque des revendications précédentes, caractérisé en ce
qu'il est appliqué à un système d'injection électronique séquentiel temporisé d'un
moteur à combustion interne.