JPH06146956A - Internal combustion engine stopping time estimating device and fuel supply device - Google Patents

Abstract

PURPOSE:To improve starting performance by presuming engine stopping time and correcting fuel quantity required for restarting an engine based on the difference between engine temperature and outside air temperature when the engine starts and the difference between engine temperature and outside air temperature when the engine starts stored before the engine starts. CONSTITUTION:In a crank chamber compression type 2 stroke gasoline internal combustion engine 1, a control unit determines fuel injection quantity based on detection signals from an engine speed sensor 11, air flow meter 12, water temperature sensor 13 as an engine temperature detecting means, and air temperature sensor 14, controlling a fuel injection valve 9. In this case, the engine temperature and outside air temperature when the engine stops are stored in a backup RAM in the control unit 10. Based on the difference between engine temperature and outside air temperature when the engine starts and the difference between the engine temperature and the outside air temperature when the engine starts stored before the engine starts, the engine stopping time is presumed, and based on this presumed engine stopping time and the engine temperature when the engine restarts, the fuel injection quantity is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for estimating a stop time from a stop of an internal combustion engine to a start thereof, and correcting a fuel supply amount based on the estimated stop time.

[0002]

2. Description of the Related Art In an internal combustion engine in which the fuel supply amount is electronically controlled, the startability is improved by increasing the fuel supply amount and increasing the mixture ratio at the start.
In this case, the fuel increase correction coefficient is set to be larger as the engine temperature is lower and the atomization of the fuel is lower and the temperature is lower.

The detection of the engine temperature is specifically detected by the water temperature sensor through the detection of the engine cooling water temperature. However, when the temperature state is in a transient state, the cooling water temperature detected by the water temperature sensor is detected. Between the engine temperature and the engine temperature involved in fuel atomization. For example, if the engine is restarted within a short time (for example, about 2 hours) after being stopped, the water temperature sensor is exposed to the outside air and is cooled, so the water temperature sensor is cooled earlier than the actual water temperature and lower than the actual water temperature. It will be detected as, and the amount of fuel required at the start will vary,
It may be difficult to start.

Further, as a two-cycle engine, the crank chamber side is used as a kind of reciprocating compressor, and the air-fuel mixture sucked into the crank chamber through the intake holes is compressed by the reciprocating motion of the piston, and the mixture is compressed into the crank chamber. A so-called crank chamber compression type two-cycle engine, which is configured to allow air to flow into a cylinder to perform scavenging, is widely known.

In the above-mentioned two-cycle engine, the air-fuel mixture is made to flow into the cylinder through the crank chamber, and since the distance from the fuel supply section to the cylinder is long, more fuel than usual is supplied at the time of starting. The lean air-fuel ratio is avoided. However, immediately after the engine is stopped, the air-fuel mixture remains in the crank chamber, and when restarting before the residual fuel evaporates, the fuel supply amount at the time of start is reduced by the remaining amount and the air-fuel mixture is emptied. It is necessary to prevent the fuel ratio from becoming rich.

Therefore, conventionally, the control unit for controlling the fuel supply amount measures the elapsed time from the stop of the engine, and at the time of restart, predicts the residual fuel amount based on the elapsed time from the stop of the engine and starts the engine. The fuel supply amount at that time was corrected. By the way, when measuring the elapsed time from the engine stop as described above to correct the fuel supply amount at the start, when restarting while the power supply to the control unit is continuously supplied during the stop The control unit can accurately measure the operation stop time, so you can make the desired correction, but if the power supply to the control unit is stopped by the operation of the engine key (ignition switch), the control unit will start operating. It becomes impossible to measure the stop time.

Therefore, the control unit is kept in the ON state for a certain period of time after the engine is stopped, and the elapsed time after the engine is stopped is estimated to estimate the state of the engine and to correct the fuel injection amount at the start. However, there are the following problems. First, a power supply self-holding relay and a drive circuit for turning on the control unit for a certain period of time after turning off the engine key are required.

Secondly, power consumption is large while the control unit is continuously turned on, which may impair restartability.
The present invention has been made in view of such conventional problems, and a stop time estimation device for an internal combustion engine capable of accurately estimating an elapsed time from when the engine is stopped to when the engine is started, It is an object of the present invention to provide a fuel supply control device for an internal combustion engine, which can accurately correct the fuel supply amount based on the operation stop time estimated by the stop time estimation device.

[0009]

Therefore, the apparatus for estimating the stop time of an internal combustion engine according to the present invention, as shown by the solid line in FIG. 1, detects the temperature state of the engine and the outside air temperature. Outside temperature detecting means, temperature storing means for storing the engine temperature and the outside air temperature when the engine is stopped, the temperature difference between the engine temperature and the outside air temperature when the engine is started, and the engine was stopped before the start. And a stop time estimating means for estimating a stop time from when the engine is stopped to when the engine is started based on a temperature difference between the engine temperature and the outside air temperature stored in the temperature storage means. did.

Further, the fuel supply control device for an internal combustion engine according to the present invention, as additionally shown by a dotted line in the figure, shows the engine stop time estimated by the stop time estimation device and the engine stop time detected at the start. The fuel supply amount correcting means for correcting the fuel supply amount to the engine based on the temperature is included.

[0011]

In the stop time estimating device, when the operation of the engine is stopped, the difference between the engine temperature detected by the engine temperature detecting means and the outside air temperature detected by the outside air temperature detecting means is large immediately after the stop, but after the stop, As the elapsed time increases, the engine temperature approaches the outside air temperature.

Therefore, the elapsed time is estimated based on the temperature difference between the two detected temperatures when the engine is stopped and the temperature difference when the engine is restarted. Further, in the fuel supply control device, the fuel supply amount when the engine is restarted is corrected based on the stop time estimated as described above.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of one embodiment, an internal combustion engine 1
Is a crank chamber compression type two-cycle gasoline engine in which the air-fuel mixture compressed in the crank chamber 2 is introduced into the cylinder 3 to perform scavenging.

An intake hole 4, a scavenging hole 5, and an exhaust hole 6 are provided on the wall surface of the cylinder 3, and the low pressure generated in the lower part of the piston 7 in the compression stroke causes the intake hole in the crank chamber 2. When the piston 7 passes through the exhaust hole 6 at the end of the compression stroke, the combustion gas in the cylinder 3 is discharged through the exhaust hole 6, and when the piston 7 goes down, the scavenging hole 5 is formed. It communicates with the crank chamber 2, and the air-fuel mixture compressed in the crank chamber 2 flows into the cylinder 3 to scavenge the exhaust gas.

In the intake passage 8 communicating with the intake hole 4,
An electromagnetic fuel injection portion 9 is provided, and a fuel mixture injected and supplied from the fuel injection valve 9 forms an air-fuel mixture and flows into the crank chamber 2 from the intake hole 4. The fuel injection valve 9 is opened by a valve opening drive signal sent from a control unit 10 with a built-in microcomputer, and injects and supplies fuel adjusted to a predetermined pressure. The fuel supply amount can be controlled by.

The control unit 10 includes an engine rotation signal from a rotation sensor 11 built in a distributor (not shown), an intake air flow rate signal from an air flow meter 12 installed in an intake passage 8 upstream of the fuel injection valve 9, The water temperature signal from the water temperature sensor 13 as the engine temperature detecting means for detecting the cooling water temperature T _w of the engine 1 and the outside air temperature signal from the air temperature sensor 14 as the outside air temperature detecting means for detecting the outside air temperature are inputted. The fuel injection amount is determined based on the detection signals from these sensors, and a valve opening drive signal corresponding to this is output to the fuel injection valve 9. The voltage of the battery 16 is applied to the control unit 10 via the ignition switch 15.

Next, a routine for estimating the elapsed time from the stop of engine operation to the restart by the control unit 10 will be described with reference to the flowchart shown in FIG.
This routine uses the ignition switch (IGSW)
This is executed when 15 is turned on and power is supplied to the control unit 10. Incidentally, this routine corresponds to the stop time estimating means.

First, in step (denoted as S in the drawing, the same applies hereinafter) 1, initialization processing is performed. In the next step 2, as shown in another routine to be described later, the water temperature T _WOFF detected by the water temperature sensor 13 when the engine operation was stopped last time and stored in the backup RAM as temperature storage means is read.

In step 3, similarly, the temperature T _AOFF detected by the temperature sensor 14 and stored in the RAM when the engine operation is stopped last time is read. In step 4, the difference between the water temperature T _WOFF and the temperature T _AOFF (T _WOFF
-T _AOFF ) is calculated and set as T _NOFF . In step 5, the current water temperature T _WON (when the ignition switch is ON) is read.

At step 6, the current temperature T _AON is read. In step 7, the current water temperature T _WON and temperature T _AON
And the difference (T _WON -T _AON ) is calculated and set as T _NON . In step 8, the current temperature difference T _NON calculated in step 7 is compared with a predetermined value RTNON to determine whether T
If it is determined that _NON <RTNON, it is determined that the water temperature is approaching the temperature to the limit because the operation stop time is sufficiently long, and the process proceeds to step 13 to set the operation stop time T _OFF to infinity, Exit the routine.

If it is determined in step 8 that T _NON ≧ RTNON, the process proceeds to step 9 and the deviation (T _NOFF -T) between the temperature difference T _NOFF at the time of the previous operation stop and the current temperature difference T _NON.
NON ) is calculated and set as T _NOFTM . Next, at step 10, the basic elapsed time T _SFOF during engine stop for the deviation T _NOFTM obtained at step 9 is searched experimentally in advance from a map table stored in the ROM. The characteristic of the basic elapsed time T _SFOF is set as shown in the block of step 9 in the figure. That is, because it tends to result deviation T _NOFTM to greatly reduced compared to the temperature towards the water temperature T _W enough to increase the stop time increases, so that the basic elapsed time T _SFOF as deviation T _NOFTM increases increases Is set to.

In step 11, the basic elapsed time T obtained in step 10 is determined by the temperature difference T _NOFF when the engine was stopped last time.
Search map table the correction coefficient T _OFKC stored in the ROM for correcting _SFOF. The characteristic of the correction coefficient T _OFKC is set as shown in the block of step 10 in the figure. That is, the larger the temperature difference T _NOFF when the engine is stopped, the larger the deviation T _NOFTM becomes even with the same stop elapsed time. _Therefore , the basic elapsed time T _SFOF should be greatly reduced and corrected as the temperature difference T _NOFF increases. Small value (<1)
Is set to.

In step 12, the basic elapsed time T _{SFOF is set.
Is} multiplied by the correction coefficient T _OFKC to estimate and calculate the engine stop time T _OFF . With this configuration, the engine is restarted in a relatively short time after the engine is stopped, and when the air-fuel mixture remains in the crank chamber, the elapsed time from the stop to the restart can be accurately estimated.

FIG. 4 shows a flow chart of a routine for leaving the water temperature T _WOFF and the outside air temperature T _AOFF when the engine is stopped in the backup RAM. This routine
It is executed by interrupting at regular intervals, and at step 21, the water temperature T
_{Since WOFF} and the outside air temperature T _AOFF are respectively stored and updated in step 22, the value stored immediately before is left when the engine is stopped.

Next, FIG. 5 shows a routine for correcting and setting the fuel supply amount based on the elapsed time estimated as described above.
It will be described in accordance with the flowchart of. This routine
It is executed every predetermined minute time (for example, 10 ms). Note that this routine corresponds to the fuel supply amount correction means. Step 31
Then, the basic fuel injection amount T _P (= K · Q / N; K is a constant) is calculated from the intake air flow rate Q and the engine rotation speed N.

In step 32, various correction factors COEF are calculated based on the operating state mainly of the water temperature T _w . In step 33, the voltage correction amount T _s for correcting the change in the effective valve opening time of the fuel injection valve 9 due to the battery voltage is set.

In step 34, the fuel injection amount T _i (= T _P · COEF + T) during normal operation is calculated based on the basic fuel injection amount T _P , various correction coefficients COEF, and the voltage correction amount T _s.
s ) is calculated. The drive signal corresponding to the fuel injection valve T _i is output to the fuel injection valve 9 at a predetermined timing to execute the fuel supply control during the normal operation.

On the other hand, at the time of starting (when the starter motor is ON), the starting fuel injection amount T _ST for injecting a larger amount of fuel than the normal fuel injection amount T _i is separately set. That is, when the ON state of the starter switch (not shown) is determined in step 35, the routine proceeds to step 36, where the starting fuel injection amount T _ST is set. In step 37, the operation stop time T _OFF obtained in FIG. 3 is read.

In step 38, the fuel injection amount T at startup is set._STTo
Fuel correction factor at start K for correction_TStop the operation
Time T_OFFSet based on. Here, when the operation is stopped
Interval T _OFFThe shorter the value is, the fuel correction coefficient K at start_TIs small
Is set to a certain value, and the operation stop time T_OFFAs gets longer
The correction coefficient K for a predetermined time or more._TIs set to 1
It is set.

In step 39, the starting fuel injection amount T _ST obtained in step 36 is multiplied by the starting correction coefficient K _T to set the correction. As described above, the correction coefficient K _T is set to a value smaller than 1 when the time from the stop of the operation is short, so that the fuel injection amount T at the start T
_ST is reduced by an amount commensurate with the amount of residual air-fuel mixture in the crank chamber 2 to prevent enrichment of the air-fuel ratio at the time of starting.

At the time of starting, the control unit 10 outputs a drive signal corresponding to the starting fuel injection amount T _ST to the fuel injection valve 9. Further, in the present embodiment, it is shown that the present invention is applied to a two-cycle engine and corrects the residual air-fuel mixture amount in the crank chamber based on the estimated operation stop time. However, in the case of a four-cycle engine, it is detected by a water temperature sensor. It is possible to correct the fuel supply amount due to the deviation in the temperature transient state between the engine temperature and the engine temperature related to the atomization characteristics of the fuel, by the operation stop time, and thereby improve the starting performance.

Further, the estimation of the operation stop time not only contributes to the correction of the fuel supply amount at the time of starting, but also contributes to the correction of the line pressure in the automatic transmission, for example, because it contributes to the oil temperature. You can

[0033]

As described above, according to the present invention, the operation stop time can be accurately calculated based on the temperature difference between the engine temperature and the outside air temperature stored when the engine is stopped and the same temperature difference at the time of start. It is possible to make an estimation, and thereby it is possible to accurately correct the fuel supply amount at the time of starting.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration and functions of the present invention.

FIG. 2 is a diagram showing a system configuration of an embodiment of the present invention.

FIG. 3 is a flowchart showing an operation stop time estimation routine according to the embodiment.

FIG. 4 is a flowchart showing a routine for storing the engine temperature and the outside air temperature when the operation is stopped according to the embodiment.

FIG. 5 is a flowchart showing a routine for correcting the fuel supply amount at the time of starting according to the embodiment.

[Explanation of symbols]

 1 Internal combustion engine 9 Fuel injection valve 10 Control unit 13 Water temperature sensor 14 Air temperature sensor

Continuation of the front page (72) Inventor Michiyuki Fujimoto 1672 1 Kasukawa-cho, Isesaki-shi, Gunma Nippon Electric Equipment Co., Ltd.

Claims (2)

[Claims] 1. An engine temperature detecting means for detecting a temperature state of an engine, an outside air temperature detecting means for detecting an outside air temperature, a temperature storing means for storing an engine temperature and an outside air temperature when the engine is stopped, and an engine. The engine is stopped based on the temperature difference between the engine temperature and the outside air temperature at the time of starting and the temperature difference between the engine temperature and the outside air temperature stored in the temperature storage means when the engine is stopped before the starting. A stop time estimating device for estimating the stop time from the start to the start, and a stop time estimating device for an internal combustion engine. 2. A fuel supply amount correction means for correcting the fuel supply amount to the engine based on the engine stop time estimated by the stop time estimation device according to claim 1 and the engine temperature detected at the time of starting. A fuel supply control device for an internal combustion engine, comprising: