[0001] This invention relates to an idling speed control apparatus for an internal combustion
engine according to the preamble of claim 1, and more particularly to an idling speed
control apparatus for an internal combustion engine which regulates the intake air
amount by means of a step motor to control the speed of rotation of the internal combustion
engine upon idling.
[0002] An idling speed control apparatus for an internal combustion engine according to
the preamble of claim 1 is known from
US-A-4 747 379.
[0003] Generally, in an idling speed control apparatus for an engine, an idling speed control
valve (ISCV) is in most cases provided midway of a bypass path provided separately
from an intake path in such a manner as to bypass a throttle valve. By regulating
the opening of the ISCV, the intake air amount of the internal combustion engine is
controlled, independently of the throttle valve, to control the idling speed.
[0004] The ISCV described above is driven by a step motor, and the opening thereof is controlled
by supplying to the step motor a pulse signal which corresponds to the difference
between the present position of an idling regulation valve which is determined by
the operation step number of the step motor from a reference position and a target
position which depends upon the operation condition of the engine. Such a control
method as just described is known, for example, by the official gazette of
Japanese Patent Laid-open No. Sho 63-42106 and so forth.
[0005] In the prior art described above, in order to make it possible to simply make the
opening of the idling regulation valve and the operation step number of the step motor
correspond to each other without using a reference position sensor such as a potentiometer
or a limit switch, a fixed pulse signal is provided to the step motor to drive the
idling regulation valve to its fully closed or fully open position immediately after
the ignition switch is disconnected, and the operation step number of the step motor
is reset in order to use the fully closed or fully open position as a reference position.
[0006] However, according to such an initial processing method as just described, since
the step motor must be rotated to the fully open or fully closed position after the
engine ignition switch is interrupted, a battery for the initial processing must further
be incorporated separately from an original battery.
[0007] It is an object of the present invention to provide an idling speed control apparatus
for an internal combustion engine using a step motor for actuating an idling valve
which can perform positioning of the step motor accurately without additionally providing
a reference position sensor or an operation step in which the step motor is reset
in order to use the fully closed or fully open position of the idling valve as a reference
position.
[0008] This object is achieved by an idling speed control apparatus for an internal combustion
engine according to claim 1.
[0009] An idling speed control apparatus for an internal combustion engine which includes
an idling regulating valve for regulating the opening of an idling intake path and
a step motor for driving the idling regulating valve to perform opening and closing
movements and which controls the rotational position of the step motor to coincide
with a rotational position corresponding to a target opening for the idling regulating
valve comprises storage means for storing an idling reference step number, means for
registering, upon starting of the engine, the idling reference step number as a present
position step number which represents the present position of the step motor, means
for driving the step motor based on a target position step number which represents
a target position of the step motor and the present position step number, idling state
discrimination means for discriminating whether or not the idling is in a steady state,
means for rewriting the present position step number into a reference step number
which is a predetermined constant when it is discriminated that the idling is in a
steady state, and means for storing the present position step number as the idling
reference step number when it is discriminated that the idling is in a steady state.
[0010] The opening of the idling regulation vale when idling is stable and in a steady state
is determined uniquely, and even if the engine is stopped, the idling regulation valve
is kept at the position. Thus, according to the characteristic described above, the
rotational position of the step motor when idling is in a steady state is stored as
the idling reference step number, and when the engine is started next, the rotational
position of the step motor at the point of time is set to the idling reference step
number stored in advance. Consequently, the relationship between the rotational position
of the step motor and the operation step number which represents the present position
of the step motor can be determined accurately without using a sensor.
[0011] According to the present invention, the following effects are achieved.
- (1) Since the rotational position of the step motor when idling is in a steady state
is set to a predetermined reference step number (Pidle) based on the empirical rule
that the rotational position of a step motor when idling is stable and in a steady
state is substantially fixed, the relationship between the present position of the
step motor and the present position step number which represents the present position
can be compensated for accurately without using a sensor.
- (2) In a transition state in which the idling is not stable, the step number Px which
represents the rotational position of the step motor at the current point of time
is repetitively stored as the engine stop step number Pstop in a non-volatile fashion,
and then when the engine is started next, the engine stop step number Pstop is initialized
as the present position step number Px which represents the rotational position of
the step motor at present. Accordingly, even if the engine is stopped in a state wherein
the idling is not stable, the present position step number Px and the present position
of the step motor can be made correspond accurately to each other.
[0012] FIG. 1 is a schematic sectional view showing a configuration of a principal portion
of an idling speed control apparatus to which the present invention is applied.
[0013] FIG. 2 is a functional block diagram showing a configuration of a controller of FIG.
1.
[0014] FIG. 3 is a flow chart illustrating operation of the present embodiment.
[0015] FIG. 4 is a flow chart illustrating operation of the present embodiment.
[0016] FIG. 5 is a time chart illustrating operation of the present embodiment.
[0017] FIG. 6 is a diagram illustrating an example of a first warming-up table.
[0018] FIG. 7 is a diagram illustrating an example of a second warming-up table.
[0019] In the following, a preferred embodiment of the present invention is described with
reference to the drawings. FIG. 1 is a schematic sectional view showing a configuration
of a principal portion of an idling speed control apparatus to which the present invention
is applied.
[0020] A throttle body 2 is mounted at an intermediate portion of an intake path which interconnects
an air cleaner and an engine. On the throttle body 2, a throttle valve 3 which regulates
the opening of the intake path is provided for pivotal motion, and also an idling
intake path 4 which bypasses the throttle valve 3 is mounted. The idling intake path
4 introduces intake air for idling to the engine upon idling of the engine and an
idling regulation valve 6 is mounted between the upstream side 4a and the down stream
side 4b of the idling intake path 4.
[0021] The opening of the idling regulation valve 6 depends upon the rotational position
of a step motor 1 which is driven with a pulse signal outputted from a controller
5. The controller 5 receives detection signals from a temperature sensor 7 which detects
a cooling water temperature of the engine, an engine speed sensor 8 which detects
an engine speed Ne, and a position sensor 9 which detects a gear position of a transmission,
and controls the rotational position of the step motor 1.
[0022] As described in detail below, an engine stop step number Pstop which represents the
rotational position of the step motor 1 upon last stopping of the engine is stored
in a non-volatile EEPROM 11 which does not require backup power. Upon next starting
of the engine, the controller 5 reads in the engine stop step number Pstop from the
EEPROM 11, and supposes that the step number Pstop represents the rotational position
of the step motor 1 at present (upon last engine stopping, that is, upon present engine
starting) to start control.
[0023] FIG. 2 is a functional block diagram showing a configuration of the controller 5,
and like elements to those appearing as above are denoted by like or equivalent reference
characters.
[0024] In the controller 5, an engine starting discrimination section 51 discriminates whether
or not the engine is started. An idling state discrimination section 52 discriminates
whether or not the idling is stabilized and settled in a steady state. A warming-up
discrimination section 53 discriminates whether or not the engine is in a warming-up
operation state.
[0025] A present position counter 54 counts a present position step number Px which represents
the rotational position of the step motor 1 at present. A target position step number
Pt relating to the step motor 1 is registered into a target position counter 55. A
motor driving section 56 supplies a driving pulse for forward rotation or reverse
rotation to the step motor 1 so as to make the present position step number Px and
the target position step number Pt coincide with each other. The driving pulse is
counted by the present position counter 54 and the present position step number Px
is incremented or decremented in accordance with the driving pulse.
[0026] Operation of the present embodiment is described below. FIGS. 3 and 4 are flow charts
illustrating operation of the present embodiment and FIG. 5 is a time chart illustrating
operation of the present embodiment.
[0027] If an ignition switch is switched on at time t1 of FIG. 5, then the idling speed
control of FIG. 3 starts. At step S1, the engine starting discrimination section 51
of the controller 5 discriminates whether or not the engine is in a starting state
based on the engine speed Ne detected, for example, by the Ne sensor 8. In the present
embodiment, when the engine speed Ne is 700 rpm or less, it is discriminated that
the engine is in a starting state. In the beginning of the process, since it is discriminated
that the engine is in a starting state, the process advances to step S11.
[0028] At step S11, as described in detail below, the engine stop step number Pstop which
represents the rotational position of the step motor 1 upon last stopping of the engine
is read out from the EEPROM 11 by the controller 5.
[0029] At step S12, the read out engine stop step number Pstop is registered as the present
position step number Px which represents the rotational position of the step motor
1 into the present position counter 54 of the controller 5.
[0030] At step S13, a warming-up step number Padd for temporarily raising the idling speed
upon warming-up operation is detected based on the present cooling water temperature
Te detected by the temperature sensor 7 with reference to a first warming-up table
101 of a ROM 10.
[0031] FIG. 6 is a graph showing an example of the first warming-up table in the present
embodiment. The warming-up step number Padd increases as the cooling water temperature
Te decreases.
[0032] At step S14, an idling reference step number Pidle (50 steps in the present embodiment)
fixedly determined in advance as a reference step number upon idling is read out from
the ROM 10.
[0033] At step S15, a sum value [Pidle + (Padd - Pstop)] of the idling reference step number
Pidle and a value obtained by subtracting the engine stop step number Pstop from the
warming-up step number Padd is registered as a present target position step number
Pt into the target position counter 55 of the controller 5.
[0034] At step S16, the present position step number Px is stored as the engine stop step
number Pstop into the EEPROM 11. At step S17, the step motor 1 is controlled by the
motor driving section 56 of the controller 5 so that the target position step number
Pt and the present position step number Px coincide with each other.
Then, the engine is started at time t2 of FIG. 5, and when the starting of the engine
is detected in step S1 described above, the process advances to step S2. At step S2,
whether or not the engine is in a no-load state is discriminated based on, for example,
the gear position detected by the gear position sensor 9. If the gear position is
the neutral position, then it is discriminated that the engine is in a no-load state,
and the process advances to step S3.
[0035] At step S3, whether or not the engine is in an idling state is discriminated based
on, for example, the engine speed Ne and the throttle opening. If the engine speed
Ne is lower than a predetermined reference speed and the throttle opening is lower
than a predetermined reference opening, then it is discriminated that the engine is
in an idling state, and the process advances to step S4. It is to be noted that, if
any one of the discriminations in steps S2 and S3 results in the negative, then the
process advances to a running mode of step S10.
[0036] At step S4, it is discriminated by the warming-up discrimination section 53 of the
controller 5 based on, for example, the water temperature Te of cooling water whether
or not the engine is in a warming-up state. In the beginning of the process, the water
temperature Te is low and it is discriminated that the engine is in a warming-up state,
and the process advances to step S5. At step S5, an upper limit value Nmax1 and a
lower limit value Nmin1 of a target idling speed range are determined based on a second
warming-up table, of which an example is shown in FIG. 7, and the water temperature
Te.
[0037] At steps S6 and S7, it is discriminated whether or not the engine speed Ne is higher
than the upper limit value Nmax1 and whether or not the engine speed Ne is lower than
the lower limit value Nmin1, respectively. If the engine speed Ne reaches the upper
limit value Nmax1 as at time t3 of FIG. 5, the target position step number Pt is decremented
at step S8. On the contrary if the engine speed Ne drops to the lower limit value
Nmin1, then the target position step number Pt is incremented at step S9. If the engine
speed Ne is within the range between the upper and lower limit values, then the process
advances immediately to step S16 et seq.
[0038] The processes described above are repeated as long as it is discriminated at step
S4 that the engine is in a warming-up state, and within the period, the cooling water
temperature Te rises gradually. Accordingly, also the upper limit value Nmax1 and
the lower limit value Nmin1 of the target idling speed range determined at step S5
described above gradually drop, and therefore, also the engine speed Ne gradually
drops as shown in FIG. 5.
[0039] Thereafter, if the water temperature Te exceeds the predetermined reference temperature
at time t4 of FIG. 5, then since it is discriminated at the next step S4 that the
engine is not in a warming-up state, the process advances to step S21 of FIG. 4.
[0040] At step S21, an idling stability flag Fidle is referred to. The idling stability
flag Fidle is set, as hereinafter described in detail, when idling is stabilized and
it is discriminated that the idling is in a steady state. Since, in the beginning
of the process, the idling is in a transition state and the idling stability flag
Fidle is in a reset state, the process advances to step S22. At step S22, the target
rotational range for the engine speed Ne is set to a rather narrow value ΔNn.
[0041] At step S23, it is discriminated whether or not the engine speed Ne has converged
to a value within the target rotational range ΔNn. Since, in the beginning of the
process, it is discriminated that the engine speed Ne has not converged, the process
advances to step S28. At step S28, the idling stability flag Fidle is reset. At step
S29, it is discriminated whether or not the engine speed Ne is higher than the upper
limit value to the target rotational range ΔNn. If the engine speed Ne reaches the
upper limit value as at time t5 of FIG. 5, then the target position step number Pt
is decremented at step S30, whereafter the process advances to step S16 et seq. On
the contrary, if the engine speed Ne is lower than the upper limit value, then the
target position step number Pt is incremented at step S31, whereafter the process
advances to step S16 et seq.
[0042] At steps S16 and S17, the present position step number Px is stored as the engine
stop step number Pstop into the EEPROM 11 in a similar manner as described hereinabove,
and motor control for making the present position step number Px coincide with the
target position step number Pt is performed.
[0043] Thereafter, the engine speed Ne converges to a value within the target rotational
range ΔNn. When this is detected at step S23 described hereinabove, then the process
advances to step S24. At step S24, the idling stability flag Fidle is referred to
again, and if the idling stability flag Fidle is in a reset state, then the process
advances to step S25. At step S25, the present position step number Px of the present
position counter 54 and the target position step number Pt of the target position
counter 55 are rewritten uniformly by the idling reference step number Pidle (= 50)
irrespective of the step number at present. At step S26, the idling stability flag
Fidle is set.
[0044] At the following steps S16 and S17, the present position step number Px is stored
as the engine stop step number Pstop into the EEPROM 11 in a similar manner as described
hereinabove, and motor control for making the present position step number Px coincide
with the target position step number Pt is performed.
[0045] In this manner, in the present embodiment, the rotational position of the step motor
when idling is in a steady state is set to a predetermined reference step number (Pidle)
based on the empirical rule that the absolute rotational position of a step motor
when idling is stable and in a steady state is substantially fixed. Therefore, the
relationship between the present position of the step motor and the present position
step number which represents the present position can be compensated for accurately
without using a sensor.
[0046] To provide an idling speed control apparatus for an internal combustion engine which
can perform positioning of a step motor accurately without additionally providing
a battery.
The idling speed control apparatus includes storage means 11 for storing an engine
stop step number Pstop, means for driving the step motor based on a target position
step number Pt which represents a target position of the step motor and a present
position step number Px which represents the present position of the step motor, and
idling state discrimination means 52 for discriminating whether or not the idling
is in a steady state. Upon starting of the engine, the engine stop step number Pstop
is registered as the present position step number, and when it is discriminated that
the idling is in a steady state, the present position step number is rewritten into
a reference step number which is a predetermined constant and the present position
step number is stored as the idling reference step number.
1. Leerlaufdrehzahl-Steuer/Regelvorrichtung für einen Verbrennungsmotor, welche ein Leerlauf-Stellventil
(6) umfasst zum Einstellen der Öffnung eines Leerlauf-Ansaugwegs (4) und einen Schrittmotor
(1) umfasst zum Antreiben des Leerlauf-Stellventils (6), um Öffnungs- und Schließbewegungen
durchzuführen, und welche die Drehposition des Schrittmotors (1) derart steuert/regelt,
dass diese mit einer Drehposition übereinstimmt, welche einer Soll-Öffnung des Leerlauf-Stellventils
(6) entspricht, umfassend:
Mittel (5) zum Antreiben des Schrittmotors (1) basierend auf einer Soll-Position-Schrittzahl
(Pt), welche eine Soll-Position des Schrittmotors (1) darstellt, und einer Ist-Position-Schrittzahl
(Px), welche eine Ist-Position des Schrittmotors (1) darstellt; und
Leerlaufzustand-Unterscheidungsmittel (52) zum Unterscheiden, ob sich der Leerlauf
in einem stabilen Zustand befindet oder nicht,
dadurch gekennzeichnet, dass die Leerlaufdrehzahl-Steuer/Regelvorrichtung ferner umfasst:
Speichermittel (11) zum wiederholten Speichern der Ist-Position-Schrittzahl (Px) als
eine Motor-Stopp-Schrittzahl (Pstop) in einer permanenten Art und Weise;
Mittel (5) zum Halten des Schrittmotors (1) und des Leerlauf-Stellventils (6) in der
Ist-Position beim Stopp des Motors;
Mittel (5) zum Übernehmen der Motor-Stopp-Schrittzahl (Pstop) als die Ist-Position-Schrittzahl
(Px) beim Start des Motors;
Speichermittel (10) zum Speichern einer vorherbestimmten Leerlauf-Referenz-Schrittzahl
(Pidle), welche im Voraus fest bestimmt ist; und
Mittel (5) zum Umschreiben der Ist-Position-Schrittzahl (Px) und der Soll-Position-Schrittzahl
(Pt) durch die vorherbestimmte Leerlauf-Referenz-Schrittzahl (Pidle), wenn unterschieden
ist, dass sich der Leerlauf in einem stabilen Zustand befindet.
2. Leerlaufdrehzahl-Steuer/Regelvorrichtung für einen Verbrennungsmotor nach Anspruch
1, dadurch gekennzeichnet, dass die Mittel (11) zum Speichern der Motor-Stopp-Schrittzahl (Pstop) ein Permanentspeicher
sind.
3. Leerlaufdrehzahl-Steuer/Regelvorrichtung für einen Verbrennungsmotor nach Anspruch
1 oder 2,
dadurch gekennzeichnet, dass sie umfasst
Mittel (7) zum Erfassen einer Kühlwassertemperatur (Te) beim Start des Motors, und
Mittel zum Korrigieren der Soll-Position-Schrittzahl basierend auf der erfassten Kühlwassertemperatur.
1. Appareil de commande de vitesse de ralenti pour un moteur à combustion interne qui
inclut une soupape régulatrice de ralenti (6) permettant de réguler l'ouverture d'un
passage d'admission de ralenti (4) et un moteur pas à pas (1) permettant d'entraîner
ladite soupape régulatrice de ralenti (6) pour effectuer des mouvements d'ouverture
et de fermeture et qui commande la position de rotation dudit moteur pas à pas (1)
pour qu'elle coïncide avec une position de rotation correspondant à une ouverture
cible pour ladite soupape régulatrice de ralenti (6), comprenant :
un moyen (5) permettant d'entraîner ledit moteur pas à pas (1) d'après un nombre de
pas de position cible (Pt) qui représente une position cible dudit moteur pas à pas
(1) et un présent nombre de pas de position (Px) qui représente une présente position
du moteur pas à pas (1) ; et
un moyen de détermination d'état de ralenti (52) permettant de déterminer si le ralenti
est ou non dans un régime permanent,
caractérisé en ce que l'appareil de commande de vitesse de ralenti comprend en outré :
un moyen de stockage (11) pour stocker de façon répétitive le présent nombre de pas
de position (Px) comme un nombre de pas d'arrêt de moteur (Pstop) de manière non volatile
;
un moyen (5) pour maintenir le moteur pas à pas (1) et la soupape régulatrice de ralenti
(6) à la présente position lors d'un arrêt du moteur ;
un moyen (5) pour adopter le nombre de pas d'arrêt de moteur (Pstop) comme le présent
nombre de pas de position (Px) lors d'un démarrage du moteur ;
un moyen de stockage (10) pour stocker un nombre de pas de référence de ralenti prédéterminé
(Pidle) déterminé fixement à l'avance ; et
un moyen (5) pour réécrire le présent nombre de pas de position (Px) et le nombre
de pas de position cible (Pt) par le nombre de pas de référence de ralenti prédéterminé
(Pidle) lorsqu'il est déterminé que le ralenti est dans un régime permanent.
2. Appareil de commande de vitesse de ralenti pour un moteur à combustion interne selon
la revendication 1, caractérisé en ce que ledit moyen (11) pour stocker le nombre de pas d'arrêt de moteur (Pstop) est une
mémoire non volatile.
3. Appareil de commande de vitesse de ralenti pour un moteur à combustion interne selon
la revendication 1 ou 2,
caractérisé en ce qu'il comprend
un moyen (7) pour détecter une température d'eau de refroidissement (Te) lors d'un
démarrage du moteur, et
un moyen pour corriger le nombre de pas de position cible d'après la température d'eau
de refroidissement détectée.