JPH05214986A - Stating fuel injection quantity control method for engine - Google Patents

Abstract

PURPOSE:To simply and correctly control the fuel injection quantity by estimating the residual deposit fuel coefficient at the time of the previous stop of an engine based on the difference between the temperature at the time of the start of the engine and the temperature at the time of the stop during the previous operation stored in a readable/writable nonvolatile memory. CONSTITUTION:An ECU 31 is inputted with detection signals from sensors 8, 9a, 9b, 20, 21, 23, 27, 29, 30 detecting the operational states of an engine. The ECU 31 calculates control signals via a CPU 32 based on the detection signals. It outputs the control signals to an ISCV 11, an injector 12, and an ignitor 30 respectively. The residual deposit fuel coefficient at the time of the previous stop of the engine is estimated based on the data stored in a backup RAM 34a which is a nonvolatile memory. The temperature compensation for the residual deposit fuel coefficient is set based on the engine temperature at the time of the start. The starting basic injection quantity is corrected in response to the residual deposit fuel coefficient corrected with the temperature compensation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a fuel injection amount at the time of starting an engine capable of obtaining good starting and restarting performance.

[0002]

2. Description of the Related Art The required fuel injection amount at the time of starting is determined by the external environment of the engine (outside air temperature, cooling water temperature as engine temperature,
Although it is affected by the fuel temperature, etc., it is generally set based on the cooling water temperature only. In the case of a cold start or the like in which the cooling water temperature is low, the fuel adhering to the intake port or the like is difficult to vaporize, so the fuel injection amount at the start is increased. On the other hand, the amount of fuel injection at the time of starting is reduced in a hot restart or the like in which the cooling water temperature is relatively high.

In this type of control system, the key switch is turned on once.
When FF is performed, the data stored in the RAM is lost, so the fuel injection amount at restart is reset based on the cooling water temperature at that time. Therefore, for example, stop the engine in a state where warm-up is not completed after starting (press the key switch to open
F) Then, if the cycle of restarting is repeated, the air-fuel ratio becomes too rich and smoldering and fogging occur on the spark plug, making restarting extremely difficult. For example, in JP-A-64-8330, wall surface adhering fuel amount data stored in advance in the ROM is searched based on the engine operating state immediately before the engine stall, and the wall surface adhering fuel amount is calculated as the cooling water temperature and the engine. Based on the time from the stall occurrence to the start of cranking, it is corrected by the restart correction coefficient searched for in the map, and this correction value is calculated from the starting fuel injection amount set according to the engine operating conditions such as cooling water temperature and cranking speed. A technique is disclosed in which the actual correction injection amount at start-up is set by subtraction.

[0004]

According to this prior art, the amount of adhered wall surface at the time of the previous engine start is set based on the engine operating state immediately before the engine stall. However, if the key switch is turned off after the engine stall. ,
Since the fuel data adhering to the wall surface at the time of stop and the timing data from engine stall to the start of cranking are all lost, an appropriate fuel injection amount at start is not set and restart becomes extremely difficult.

Therefore, in order to obtain a good restart performance, it is necessary to supply power to the ECU for at least a certain period of time after turning off the key switch to continue timekeeping and the like, which causes an increase in battery consumption. In addition, since the timer for timekeeping is required, the number of parts is increased, and the cost of the product is increased.

In the above prior art, the amount of fuel adhering to the wall surface is estimated using only the engine operating condition immediately before the engine stall as a parameter. However, it is set at the time of restarting after stopping the engine during warm-up operation. Regarding the amount of fuel adhering to the wall surface, the fuel history from the previous start to the stop is an important factor because the engine at the time of stop is not sufficiently warmed up and the amount of evaporation is small. Therefore, it is difficult to accurately estimate the residual adhered fuel amount using only the engine operating state immediately before stopping as a parameter.

The present invention has been made in view of the above circumstances, and the ECU has a simple structure even after the key switch is turned off.
It is not necessary to drive the engine, the increase in battery consumption is prevented, the number of parts is reduced, and moreover, the fuel injection amount control at engine start that can accurately estimate the amount of residual adhered fuel at start and restart is performed. It is intended to provide a way.

[0008]

In order to achieve the above object, a method of controlling a fuel injection amount at the time of starting an engine according to the present invention comprises:
Procedure for determining engine start, procedure for setting start basic injection amount based on engine temperature at start when it is determined to be engine start, and start at the time of previous operation stored in readable and writable non-volatile memory The procedure for estimating the residual adhered fuel coefficient at the time of the previous engine stop by a table search based on the difference between the engine temperature of the And a procedure for setting the starting fuel injection amount by correcting the starting basic injection amount by the residual adhered fuel coefficient corrected by the temperature compensation amount.

[0009]

According to the method for controlling the fuel injection amount at the time of starting the engine according to the present invention, at the time of starting the engine, the difference between the engine temperature at the time of starting and the engine temperature at the time of stopping in the last operation stored in the readable and writable non-volatile memory. Based on the above, a table search is performed to estimate the residual adhered fuel coefficient at the time of the previous engine stop.

Further, the temperature compensation amount at the time of the present starting with respect to the above-mentioned residual adhered fuel coefficient is set based on the engine temperature at the time of starting.

Then, when the engine is started, the starting basic injection amount set on the basis of the engine temperature at this time is corrected by the residual adhered fuel coefficient corrected by the temperature compensation amount, and only the residual adhered fuel amount at the time of starting is corrected. Set a limited starting fuel injection amount.

Since the engine temperature at the time of starting and the engine temperature at the time of stopping are stored in a readable and writable nonvolatile memory,
This data will not be lost even after the key switch is turned off. In addition, the structure is simplified because the residual adhered fuel amount at the time of starting is estimated only from the engine temperature.

Further, the residual adhered fuel coefficient is obtained from the difference between the engine temperature at the start of the previous operation and the engine temperature at the time of stop, and the residual adhered fuel coefficient is set based on the engine temperature at the present start. Since the correction is made by the temperature compensation amount, the fuel history at the previous engine operation and the temperature compensation at this time are reflected in this value. Therefore, a good fuel injection amount at startup can be set even if restarting is not completed after warming up, or even if restarting in a thermal state. It is possible to prevent darkness.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

The drawings show an embodiment of the present invention, FIG. 1 is a flow chart showing a fuel injection amount setting procedure, FIG. 2 is a flow chart showing a starting injection amount setting procedure, and FIG. 3 is an overall schematic view of an engine control system. 4 is a circuit diagram of the control device, FIG. 5 is a conceptual diagram of a residual adhered fuel coefficient table, and FIG. 6 is a conceptual diagram of a temperature compensation amount table.

[Structure of engine control system] In FIG.
Reference numeral 1 denotes an engine body, which is a horizontally opposed engine in the figure. An intake manifold 3 is communicated with an intake port 2a formed in a cylinder head 2 of the engine body 1, and a throttle chamber 5 is communicated upstream of the intake manifold 3 via an air chamber 4 to the throttle chamber 5. An air cleaner 7 is attached upstream through an intake pipe 6.

A throttle valve 5a provided in the throttle chamber 5 is provided with an intake air amount sensor (a thermal air flow meter in the drawing) 8 immediately downstream of the air cleaner 7 in the intake pipe 6. Further, a throttle opening sensor 9a and an idle switch 9b for detecting the fully closed throttle valve are connected in series.

Further, an idle speed control valve (ISCV) 11 is provided in a bypass passage 10 that connects the upstream side and the downstream side of the throttle valve 5a. An injector 12 is arranged immediately upstream of each intake port 2a of each cylinder of the intake manifold 3. An ignition plug 13 whose tip is exposed to the combustion chamber is attached to each cylinder of the cylinder head 2, and an igniter 30 is connected to the ignition plug 13.

A knock sensor 20 is attached to the cylinder block 1a of the engine body 1 and
A cooling water temperature sensor 21 for detecting a cooling water temperature as an example of an engine temperature is exposed to a cooling water passage (not shown) formed in the cylinder block 1a, and further, an exhaust gas communicating with the exhaust port 2b of the cylinder head 2 is communicated. An O2 sensor 23 is exposed to the collecting portion of the manifold 22. Reference numeral 24 is a catalytic converter.

A crank rotor 26 is rotatably mounted on a crank shaft 1b supported by the cylinder block 1a, and an electromagnetic wave for detecting a protrusion (or slit) corresponding to a predetermined crank angle is provided on the outer periphery of the crank rotor 26. A crank angle sensor 27 including a pickup and the like is provided oppositely, and a cam angle sensor 29 including an electromagnetic pickup and the like is provided opposite to the cam rotor 28 connected to the cam shaft 1c of the cylinder head 2.

[Circuit Configuration of Control Device] On the other hand, in FIG. 4, reference numeral 31 is a control device (ECU) composed of a microcomputer, etc., and includes CPU 32, ROM 33, RAM 3
4. Backup R which is a readable and writable non-volatile memory
The AM 34a and the I / O interface 35 are connected via the bus line 36, and a predetermined stabilizing power supply from the constant voltage circuit 37 is supplied.

The constant voltage circuit 37 includes an ECU relay 38.
Of the ECU relay 38 is connected to the battery 39 via a key switch 40, and a starter motor 43 is connected to the battery 39 via a starter switch 42. ..

The input port of the I / O interface 35 is connected to the sensors 8, 9a, 20, 21,
23, 27, 29 and the idle switch 9b are connected, and the output terminals of the battery 39 and the starter switch 42 are connected to monitor the battery voltage and the operating state of the starter switch 42. On the other hand, the igniter 30 is connected to the output port of the I / O interface 35, and the ISCV 11 and the injector 12 are further connected via the drive circuit 45.

The ROM 33 stores a control program and fixed data such as various control tables typified by the residual deposited fuel coefficient table TBKSTT1 and the temperature compensation table TBKSTT2, and the RAM 34.
Stores data after processing the output signals of the sensors and switches, data processed by the CPU 32, and the like. In addition, the backup RA
In M34a, a learning correction coefficient KBLRC for learning the air-fuel ratio for each operating region, a starting coolant temperature STATTW as an engine temperature at start, and a stop coolant temperature LASTTW as an engine temperature at stop are stored. Therefore, the data is retained even when the key switch 40 is off.

In the CPU 32, the crank angle sensor 27 is operated according to the control program stored in the ROM 33.
The engine speed NE is calculated from the crank angle signal from the engine speed NE, and the basic fuel injection amount TP is obtained based on the engine speed NE and the intake air amount Qa from the intake air amount sensor 8, and the output from the O2 sensor 23 is output. Based on the above, the basic fuel injection amount TP is feedback-corrected with the air-fuel ratio, and the fuel injection amount Ti at the normal time is calculated by adding the increase correction according to various operating state parameters. Further, when the engine is started, the cooling at this time is performed. The starting basic injection amount TSTAT set based on the water temperature TW is used as the starting cooling water temperature STATTW and the stopping cooling water temperature L in the previous operation.
Fuel injection amount TSTATK at start-up corrected by the residual adhesion fuel coefficient KSTT1 set based on the difference from ASTTW and the temperature compensation amount set based on the cooling water temperature TW
Is calculated.

[Operation] Next, the control operation of the ECU 31 will be described with reference to the flowcharts of FIGS. 1 and 2.

The flowchart of FIG. 1 is a routine for setting the fuel injection amount, which is executed at predetermined time intervals.
When the key switch 40 is turned on, the driving power source is turned on to the ECU 31, and the system is initialized.

First, in step (hereinafter abbreviated as "S") 101, the starter switch 42 is used to make a start determination.
The operating state of S10 is detected, and if it is ON, it is determined to be a start and S10
2 proceeds to S103 if OFF. When proceeding to S103, it is judged whether the engine speed NE calculated based on the output of the crank angle sensor 27 is 0, and NE ≠ 0 (NE> 0).
In this case, it is determined that the engine has been started, the routine proceeds to S104 to perform the normal control, the fuel injection amount Ti is calculated based on the following equation, and then the routine jumps to S109.

Ti ← TP × α × COEF × KBLRC + TS TP ← K × Qa / NE TP: Basic fuel injection amount α: Air-fuel ratio feedback correction coefficient COEF: Various increase correction coefficient KBLRC related to cooling water temperature correction, acceleration / deceleration correction, etc. : Air-fuel ratio learning correction coefficient TS: Voltage correction coefficient K: Constant (coefficient relating to injector characteristic) On the other hand, when NE = 0, that is, when it is determined that the engine is stopped in S103, the process proceeds to S102.

When the process proceeds from S101 or S103 to S102, the control at the time of start is executed, the start initial determination flag F1 is referred to in S102, and if F1 = 0 (initial start) S
The process proceeds to 105, and if F1 = 1 (routine after the second time after starting), proceeds to S108. It should be noted that the start initial determination flag F1 is cleared at the time of system initialization.
When the process proceeds to S105, the starting initial cooling water temperature STATTW (n) stored in the backup RAM 34a during the previous engine operation
And the cooling water temperature during stop LASTTW (n) are read out, and both cooling water temperatures STATTW (n) and LASTTW (n) are stored in RAM 34 at predetermined addresses.
1), Stored as the last stop cooling water temperature LASTTW (n-1) (STATTW (n-1) ← STATTW (n), LASTTW
(n-1) ← LASTTW (n)).

Next, the process proceeds to S106 and the backup RA
Starting initial cooling water temperature STATT stored in M34a
Current cooling water temperature T when W (n) is detected by the cooling water temperature sensor 21
Update with W (STATTW (n) ← TW). After that, S1
07, set the initial determination flag F1 for starting (F1 ←
1) and proceeds to S108.

Then, from S102 or S107 to S
When the routine proceeds to step 108, the program for calculating the fuel injection amount TSTATK at startup is executed (details will be described later), and then S10.
In 9, the timer is set to the injection time corresponding to the fuel injection amount Ti set in S104 or the starting fuel injection amount TSTATK set in S108, and the backup RAM 34a is set by the current cooling water temperature TW detected by the cooling water temperature sensor 21 in S110. Cooling water temperature LAS stored in
Update TTW (n) (LASTTW (n) ← TW) and exit the routine.

Since the cooling water temperature during stop LASTTW (n) is sequentially rewritten each time the flowchart is executed, when the power supply to the ECU 31 is cut off, that is, immediately before the key switch 40 is turned off and the engine is stopped. The value of will be retained as the final value. Starting fuel injection amount TSTATK executed in S108
The calculation program is shown in the startup fuel injection amount setting subroutine of FIG. 2. First, the basic injection amount at startup TSTAT is interpolated from a table search or the like based on the cooling water temperature TW detected by the cooling water level temperature sensor 21 in S201. Calculate with. The starting basic injection amount TSTAT is the total required injection amount corresponding to the cooling water temperature TW.

Next, in step S202, the previous start initial cooling water temperature STATTW (n-1) and the previous stop cooling water temperature LASTTW (n-1) stored in the RAM 34 are read out, and both cooling water temperatures STATTW (n-1) are read. , LAST TW (n-1) difference DSTT
W (DSTTW = LASTTW (n-1) -STATTW (n-
Based on 1)), the residual adhering fuel coefficient table TBKSTT1 stored in the series of addresses of the ROM 33 is searched and the residual adhering fuel coefficient KSTT1 is set.

When the engine is stopped in a state where the warm-up is not completed, there is little difference in the cooling water temperature TW at the time of starting and at the time of stopping.
The water temperature difference DSTTW becomes a small value. On the other hand, if the engine is stopped after the warm-up is completed, the water temperature difference DSTTW shows a large value. If the engine is stopped before the engine is warmed up, the cooling water temperature TW is low and the engine temperature is low, so the amount of residual fuel adhering to the wall surface is large. If the engine is stopped after sufficient warming up, the cooling water temperature TW is Since the fuel evaporation rate is high, the amount of residual adhered fuel is small. As shown in FIG. 5, in each area of the above-mentioned residual adhered fuel coefficient table TBKSTT1,
Optimal residual adhered fuel coefficient KS according to water temperature difference DSTTW
TT1 is obtained in advance from an experiment or the like and stored.

After that, the process proceeds to S203 and the cooling water temperature sensor 2
Based on the current cooling water temperature TW detected in step 1, the temperature compensation amount table TBKSTT2 stored in the ROM 33 is searched to estimate the temperature compensation amount KSTT2.

This temperature-compensated component KSTT2 simply estimates the influence of the temperature such as the fuel temperature, the intake air temperature, and the fuel vaporization amount at the time of start based on the current cooling water temperature TW. As shown in FIG. Temperature compensation table TBKS
In each area of TT2, an optimum temperature compensation amount KSTT2 corresponding to the cooling water temperature TW is obtained in advance by experiments or the like and stored.

Then, the process proceeds to S204, in which the starting basic injection amount TSTAT is corrected by the residual adhered fuel coefficient KST1 corrected by the temperature compensation amount KSTT2 to set the starting fuel injection amount TSTATK (TSTATK ← TTTT.
1 x TTT2 x TSTAT), exit the routine.

Thus, the above-mentioned starting injection amount TSTAT
K is the residual adherent fuel coefficient KSTT1 that reflects the adherent fuel history during the previous operation, and the temperature compensation amount KSTT2 at this start.
The air-fuel ratio does not become rich even if the start-stop cycle is repeated, and good starting and restarting performance is obtained, as well as spark plug fogging.
Smoldering can also be effectively avoided.

Although the cooling water temperature is used as the engine temperature in this embodiment, it is not limited to this as long as the engine temperature can be detected.

[0041]

As described above, according to the present invention,
Since the engine temperature at the time of starting and the engine temperature at the time of stopping during the previous operation are stored in a readable / writable non-volatile memory, this data will not be lost even after the key switch is turned off. Later,
Only the backup power supply for the non-volatile memory is needed, and the battery consumption is extremely low. Further, the structure is simplified because the residual adhered fuel amount at the time of engine start is estimated.

Further, the residual adhered fuel coefficient was obtained from the difference between the engine temperature at the time of starting and the engine temperature at the time of stopping in the previous operation, and this residual adherent fuel coefficient was set based on the engine temperature at the present starting. The temperature compensation amount is used for correction, and information related to temperatures such as the outside air temperature, fuel temperature, and warm-up state is simply estimated from the engine temperature only to limit the fuel injection amount at startup. It is possible to set a good fuel injection amount at startup even after restarting or hot restarting, especially when restarting after incomplete warm-up to prevent excessive air-fuel ratio Excellent effects such as effective prevention of smoldering and fogging of the plug are achieved.

[Brief description of drawings]

FIG. 1 is a flowchart showing a fuel injection amount setting procedure.

FIG. 2 is a flowchart showing a starting injection amount setting procedure.

FIG. 3 is an overall schematic diagram of an engine control system

FIG. 4 is a circuit diagram of a control device.

FIG. 5 is a conceptual diagram of a residual adhered fuel coefficient table.

FIG. 6 is a conceptual diagram of a temperature compensation table.

[Explanation of symbols]

STATTW ... Engine (cooling water) temperature at start-up during previous operation TSTAT ... Basic injection amount at start-up TW ... Engine (cooling water) temperature LASTTW ... Engine (cooling water) temperature at stop during previous operation KSTT1 ... Residual Adhesion fuel coefficient KSTT2 ... Temperature compensation amount TSTATK ... Fuel injection amount at start

Claims (1)

[Claims] 1. A procedure for determining engine start, a procedure for setting a basic injection amount at start based on engine temperature at start when it is determined to be engine start, and a previous time stored in a readable / writable nonvolatile memory. Based on the difference between the engine temperature at the time of starting and the engine temperature at the time of stopping, the procedure for estimating the residual adhered fuel coefficient at the time of the previous engine stop by a table search And a procedure for setting a temperature compensation amount for the fuel coefficient and a procedure for setting the starting fuel injection amount by correcting the starting basic injection amount by the residual adhered fuel coefficient corrected by the temperature compensation amount. And a method for controlling fuel injection amount at engine startup.