JP2001012291A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic control injection system for a diesel engine which can perform proper control of a fuel injection amount at low cost without using a fuel temperature sensor. SOLUTION: In this constitution, an operating mode of an engine 1 is calculated from a cooling water temperature of the engine 1 detected by a water temperature sensor 43, intake air temperature detected by an intake air temperature sensor 41, engine rotational speed detected by a rotational speed sensor 45, etc., and after calculating a continuation time continuing this operating mode, a fuel temperature is calculated to be estimated from the calculated operating mode and continuation time without mounting a fuel temperature sensor in a fuel injection amount control member, based on this calculated fuel temperature, a fuel injection amount injected in a sub-combustion chamber 23 of the engine 1 is correction controlled, so as to perform proper control of the fuel injection amount over the total of an operating region of the engine 1 like its starting time, its idle operation time, and vehicle running time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention estimates and calculates a fuel temperature based on an operating state of an engine, a coolant temperature and an intake air temperature, and operates the fuel injection amount control member based on the calculated fuel temperature. The present invention relates to a fuel injection control device for an internal combustion engine capable of correcting and controlling the fuel injection control.

[0002]

2. Description of the Related Art As a conventional technique, Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 45, the engine speed of a diesel engine is detected using a rotation speed sensor, the fuel temperature in a fuel injection pump is detected using a fuel temperature sensor, and the engine speed and fuel temperature are detected. By correcting the fuel injection amount injected to the diesel engine based on the
It is generally known to perform appropriate fuel injection amount control.

However, according to the fuel injection control device for a diesel engine, it is necessary to mount the fuel temperature sensor on the fuel injection amount control member, and it is necessary to secure a space for mounting the fuel temperature sensor and to accurately detect the temperature. Processing of the mounting part is required. For this reason, there is a problem that the product cost is increased and the degree of freedom in mounting design is impaired.

Therefore, conventionally, Japanese Utility Model Laid-Open Publication No.
As disclosed in Japanese Patent Publication No.
A fuel temperature is calculated based on an instruction value of an intake air temperature sensor that detects a temperature of intake air sucked by the internal combustion engine, and a fuel increase coefficient at a start is calculated based on the calculated fuel temperature,
There has been proposed a fuel injection control device for an internal combustion engine in which the valve opening time of a fuel injection valve is corrected based on the calculated fuel increase coefficient.

[0005]

However, according to the conventional fuel injection control device for an internal combustion engine, the intake air temperature and the fuel temperature are not correlated when the vehicle is not affected by the traveling wind such as when the vehicle is stopped. Yes, it can be estimated, but when the vehicle is running, the intake air temperature is affected by the traveling wind, and the intake air temperature does not change much, whereas the fuel temperature changes according to the driving state of the vehicle. Is not necessarily correlated with the fuel temperature, and it is difficult to estimate and calculate the fuel temperature over the entire operation range of the vehicle only with the intake air temperature.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in consideration of the above problems, and has been made in consideration of the followings. An object of the present invention is to provide a fuel injection control device for an internal combustion engine that can perform appropriate fuel injection amount control over the entire driving range of a vehicle, such as when the vehicle is running.

[0007]

According to the present invention, the operating state of the internal combustion engine detected by the operating state detecting means, the cooling water temperature detected by the cooling water temperature detecting means,
And a fuel temperature calculating means for estimating and calculating a fuel temperature based on the intake air temperature detected by the intake air temperature detecting means, and calculating a fuel injection amount based on the fuel temperature estimated and calculated by the fuel temperature calculating means. The fuel injection amount calculating unit includes an injection amount control unit that controls an operation state of the fuel injection amount control member based on the fuel injection amount calculated by the fuel injection amount calculating unit.

According to the first aspect of the present invention, with the above-described configuration, the fuel temperature sensor can be used without using a fuel temperature sensor.
A fuel injection that estimates and calculates a fuel temperature from a coolant temperature for cooling the internal combustion engine, an intake air temperature drawn into the internal combustion engine, and an operating state of the internal combustion engine, and injects the internal combustion engine based on the calculated indicated value of the fuel temperature. Since the amount can be corrected and controlled, the engine can be started at the time of starting the internal combustion engine, at the time of idling, during the running of the vehicle, over the entire operating range of the vehicle,
Appropriate fuel injection amount control can be performed at low cost.

[0009] The invention described in claims 2 and 3 is
As shown in FIG. 12, the operating state of the internal combustion engine detected by the operating state detecting means 101 and the cooling water temperature detecting means 102
Based on the cooling water temperature detected by the detection means and the intake air temperature detected by the intake air temperature detection means 103, an operation mode determination means 104 for determining an operation mode of the internal combustion engine, and the operation mode determination means 104 Duration calculating means 105 for calculating the time during which the operating mode of the internal combustion engine continues, and the operating mode of the internal combustion engine determined by the operating mode determining means 104 and the duration calculating means 105
Fuel temperature calculating means 106 for estimating and calculating the fuel temperature to be injected into the internal combustion engine based on the duration calculated in
Injection amount fuel temperature correction amount calculation means 107 for calculating a correction injection amount in accordance with the fuel temperature estimated and calculated by the fuel temperature calculation means 106, and correction calculated by the injection amount fuel temperature correction amount calculation means 107 And a final injection amount calculating means for calculating a final injection amount according to the injection amount.

According to the second and third aspects of the present invention, the operation mode of the internal combustion engine is determined based on the operation state of the internal combustion engine, the coolant temperature, and the intake air temperature with the above configuration. Can be. Further, the temperature of the fuel injected into the internal combustion engine can be estimated and calculated based on the operation mode of the internal combustion engine and the duration of the operation mode. This makes it possible to perform appropriate fuel injection amount control over the entire operation range of the engine and the vehicle, such as when the internal combustion engine is started, during idling, and when the vehicle is running.

According to a fourth aspect of the present invention, the operating state detecting means includes an engine speed detecting means for detecting an engine speed of the internal combustion engine, an injection amount detecting means for detecting a fuel injection amount, and a running speed of the vehicle. Any one or more of the vehicle speed detecting means for detecting the vehicle speed and the accelerator opening detecting means for detecting the accelerator opening may be used.

According to the fifth aspect of the present invention, since the actual change in the fuel temperature is different depending on the idling operation mode or the traveling operation mode, the fuel temperature calculation means determines the internal combustion state determined by the operation mode determination means. By determining the fuel temperature calculation coefficient according to the operation mode of the engine, the fuel temperature can be calculated with high accuracy.

For example, in the idling operation mode, the temperature tends to rise almost linearly up to a certain temperature with the lapse of time, and thereafter tends to stabilize. By setting the temperature calculation coefficient to a value larger than the fuel temperature calculation coefficient in a region where the fuel temperature is high after a long time has elapsed, the fuel temperature in the idle operation mode can be calculated with high accuracy.

Further, in the traveling operation mode, the actual fuel temperature rise rate tends to increase as the rotation speed changes from the low rotation and low load range to the high rotation and high load range. By setting the fuel temperature calculation coefficient as large as possible, it is possible to accurately calculate the fuel temperature in the traveling operation mode.

According to the sixth and seventh aspects of the present invention, the temperature rise characteristic of the cooling water temperature is determined by the valve opening characteristic of the thermostat. For example, after the internal combustion engine is started, the cooling water temperature rises substantially linearly up to about 80 ° C., and when it rises, the thermostat opens and the cooling water returns to the radiator. Therefore, the cooling water temperature rises slowly and draws a gentle curve. Thereafter, the valve opening lift amount of the thermostat increases with the rise of the cooling water temperature, so that the cooling water temperature is almost stabilized at about 90 to 95 ° C. Although the fuel temperature is slightly delayed with respect to the rise of the cooling water temperature, there is a correlation between the temperature rise characteristic of the cooling water temperature and the temperature rise characteristic of the fuel temperature. Temperature characteristics,
That is, the fuel temperature can be calculated with high accuracy by determining the fuel temperature calculation coefficient based on the valve opening characteristics of the thermostat.

According to the sixth and eighth aspects of the invention, in the first region from the start of the internal combustion engine to the opening of the thermostat, the temperature rise characteristic of the cooling water temperature is sharp. However, since the temperature of the air around the internal combustion engine and the temperature of the fuel injection amount control member are low immediately after the start of the internal combustion engine, the thermal conductivity tends to be low, and the rate of temperature rise of the fuel temperature tends to be low. Further, in the second region from when the thermostat opens to when the valve lift of the thermostat is stabilized, the air temperature around the internal combustion engine and the temperature of the fuel injection amount control member are lower than in the first region. Since the temperature is high, the thermal conductivity is high, and the fuel temperature tends to increase faster than in the first region.

In the third region after the valve lift of the thermostat is stabilized, the air temperature around the internal combustion engine and the temperature of the fuel injection amount control member are higher than those in the second region, and the thermal conductivity is higher. Is considered to be high, but the rate of temperature rise of the fuel temperature tends to be slower than in the second region because the temperature rise characteristic of the coolant temperature is slow. Therefore, the fuel temperature calculation coefficient in the second region from when the thermostat is opened until the valve lift of the thermostat is stabilized is calculated by calculating the fuel temperature in other regions such as the first region and the third region. By setting the value to a value larger than the coefficient, the fuel temperature can be accurately calculated.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described based on embodiments with reference to the drawings. FIG. 1 to FIG. 19 show an embodiment of the present invention, and FIG. 1 is a diagram showing the overall configuration of an electronically controlled injection system for a diesel engine.

The electronic control injection system for a diesel engine according to the present embodiment includes a multi-cylinder (four-cylinder in this embodiment) diesel engine (hereinafter abbreviated as an engine) 1 in an operating state, a running state of a vehicle, and a driver's operation amount ( Intention) is detected by various sensors, and an electronic control unit (Electron) is detected.
(ic / Control / Unit: hereinafter referred to as ECU)
9 to calculate the optimal fuel injection amount and injection timing based on information from various sensors, and to instruct a fuel injection amount control and injection timing control actuator for controlling each of them.

First, the structure of the engine 1 of this embodiment is shown in FIG.
This will be briefly described based on the above. The engine 1 has a water-cooled engine body 10 cooled by cooling water and an intake pipe 1 connected to an intake manifold of the engine body 10 to allow intake air to flow into the engine body 10.
1, and an exhaust pipe 12 connected to an exhaust manifold of the engine body 10 to allow exhaust gas to flow out of the engine body 10.

The engine body 10 of this embodiment includes a cylinder block 13, a cylinder head 14, and an oil pan 1.
5 and so on. In the cylinder block 13, a piston 19 connected to a crankshaft (crankshaft) 18 via a connecting rod 17 is provided.

Then, the cylinder head 14, the piston 1
A main combustion chamber 21 into which high-pressure fuel is injected from a fuel injection nozzle 3 described later is formed in a portion surrounded by the cylinder 9 and the cylinder 20. Further, the cylinder head 14 is formed with a sub-combustion chamber 23 in which a glow plug 22 for assisting the start of the engine 1 particularly in cold weather is mounted.

Here, the cooling system of the engine 1 of the present embodiment is a water cooling system in which cooling water for cooling the engine 1 is cooled by a radiator (radiator). That is, the cooling water cooled through the radiator (not shown) is sent into the water jacket 24 of the engine 1 by a water pump (not shown) driven by the engine 1, and the inside of the engine (the outer peripheral portion of the cylinder 20; The head 14 and the like are cooled and returned to the radiator via a thermostat (not shown).

When the temperature of the cooling water rises above a predetermined temperature (for example, 80 ° C.), the thermostat opens the valve so that the cooling water returns to the radiator. Is a flow control valve whose size becomes larger.

A throttle valve (throttle valve) 25 is provided in the intake pipe 11 of the engine 1. Exhaust gas recirculation gas (EGR gas) is supplied to the intake pipe 11.
EGR valve 2 is provided in the exhaust gas recirculation pipe 26
7 are provided.

The throttle valve 25 is provided with a vacuum pump (V /
P) 28, the intake air amount is adjusted by changing the opening degree of the intake passage formed in the intake pipe 11. Further, when driven by a vacuum pump (V / P) 29, the EGR valve 27 changes the opening degree of a recirculation passage formed in the exhaust gas recirculation pipe 26 to reduce the exhaust gas recirculation amount (EGR amount). Adjust.

Here, the engine 1 includes an intake air temperature sensor 41, an intake pressure sensor 42, a water temperature sensor 43, and a crank angle sensor 4 as sensors for sending sensor signals to the ECU 9.
4 etc. are mounted.

The intake air temperature sensor 41 is disposed in the air cleaner 40 of the engine 1 and detects intake air temperature (intake air temperature) taken into the intake pipe 11 of the engine 1.

The intake pressure sensor 42 is an intake pressure detecting means which is disposed in the intake pipe 11 and detects intake air pressure (intake pressure) taken into the intake pipe 11 of the engine 1. The water temperature sensor 43 is provided in the cylinder block 13 of the engine 1, and is a cooling water temperature detecting unit that detects a temperature of the cooling water circulating in the water jacket 24. The crank angle sensor 44 is a crank angle detecting unit that is disposed on a lower side wall of the cylinder block 13 of the engine 1 and detects an angle of the crank shaft 18.

Here, a fuel pump system (not shown) for pumping fuel in a fuel tank (not shown) and a suction pump by a feed pump are provided in a fuel pipe system of the electronic control injection system for a diesel engine according to the present embodiment. A distribution type fuel injection pump (hereinafter abbreviated as an injection pump) 2 for pressurizing the supplied fuel, and a plurality (four in this example) of fuel injection nozzles 3 from which high-pressure fuel is pumped from the injection pump 2 are provided. Have been.

The fuel injection nozzles 3 are individually mounted on the cylinder head 14 of the engine 1 corresponding to the respective cylinders so that the fuel pressurized by the injection pump 2 to a high pressure can be ignited and burned better. In addition to atomization, it has a function of spreading to every corner according to the size and shape of each sub-combustion chamber 23 in order to mix well with air.

Next, the structure of the injection pump 2 of this embodiment will be briefly described with reference to FIG. Since the configuration of the injection pump 2 is well known, a detailed description of the entire injection pump 2 will be omitted, and a configuration required for the fuel injection control device of the present invention will be described.

The injection pump 2 is driven by the rotation of a pump drive shaft (not shown) connected to the crankshaft 18 of the engine 1 via a belt or the like, and pressurizes the fuel. The fuel injection nozzle 3 for each cylinder
To pump. A disk-shaped pulsar (not shown) is attached to the pump drive shaft. On the outer peripheral surface of the pulsar, the same number of missing teeth (four in this embodiment) as the number of cylinders of the engine 1 are formed at equal angular intervals, and a predetermined number of projections are equiangularly spaced between the missing teeth. It is formed at intervals.

At a position facing the outer peripheral surface of the pulsar, a rotation speed sensor (pump angle sensor) 45 for generating a detection signal every time a projection formed on the outer peripheral surface of the pulsar crosses is provided. The rotational speed sensor 45 corresponds to the operating state detecting means of the present invention, and is an engine rotational speed detecting means for detecting the rotational speed of the injection pump 2, that is, the engine rotational speed of the engine 1.

Further, as an actuator attached to the injection pump 2, a fuel injection amount control member 4 for changing the amount of fuel injected into each sub-combustion chamber 23 of the engine 1, An injection timing control member 5 for changing the fuel injection timing is mounted.

The fuel injection amount control member 4 opens when the electromagnetic coil is not energized to overflow the fuel in the high pressure chamber into the fuel chamber, and closes when the electromagnetic coil is energized to close the high pressure chamber. An electromagnetic spill valve (SPV) or the like for stopping overflow of fuel from the fuel chamber to the fuel chamber is used. The injection timing control member 5 is a timing control valve (TC) for adjusting the fuel pressure acting as the control oil pressure of the timer device of the injection pump 2.
V) etc. are used.

The ECU 9 comprises an operation mode determining means, a duration calculating means, a fuel temperature calculating means, a fuel injection amount controlling means, a fuel injection amount calculating means, an injection amount fuel temperature correction amount calculating means, a final injection amount calculating means of the present invention. It constitutes. Inside the ECU 9, a CPU, ROM, RA (not shown)
A microcomputer including M and the like is provided, and sensor signals from various sensors are supplied to an input circuit (IN
(PUT) and then input to the microcomputer after A / D conversion.

The various sensors are the intake air temperature sensor 4
1, intake pressure sensor 42, water temperature sensor 43, crank angle sensor 44, rotation speed sensor 45, accelerator opening sensor 4
6. Vehicle speed sensor 47, air conditioner switch (A / C / S
W) 51, ignition switch (IG / SW) 5
2. Neutral switch (N-SW) 53, starter switch (ST-SW) 54, and the like.

The accelerator opening sensor 46 is accelerator opening detecting means for detecting the amount of depression of an accelerator pedal 48 (accelerator opening). The vehicle speed sensor 47 is a vehicle speed detecting means for detecting a running speed of the vehicle.

The air conditioner switch 51 is a switch for detecting operation start (ON) and operation stop (OFF) of the vehicle air conditioner (air conditioner: A / C). The neutral switch 53 is a switch for detecting whether or not the select lever for shifting the automatic transmission of the vehicle is set to the neutral (N) position.

The output circuit (OUTPUT) of the ECU 9 is connected to the fuel injection amount control member 4, the injection timing control member 5, the glow plug 22, the vacuum pumps 28 and 29, the main relay 30, and the like. Thereby, the fuel injection amount control member 4, the injection timing control member 5, the glow plug 2
2. Vacuum pumps 28 and 29 and main relay 3
0 is electronically controlled by the ECU 9.

Next, a control method of the electronically controlled injection system for a diesel engine according to the present embodiment will be briefly described with reference to FIGS. 1 to 11. here,
2 to 7 are control flowcharts showing a control program of the ECU 9.

First, sensor signals from various sensors and switch signals from various switches are taken in. Specifically, the engine speed (NE), the accelerator opening (ACC)
PF), fuel injection amount (QFIN), cooling water temperature (TH
W), intake air temperature (THA), vehicle speed, intake pressure, starter switch signal, and idle switch signal are fetched (step S1).

Next, it is determined whether or not the engine 1 has been started based on the information obtained in step S1 (step S1).
2). If the result of this determination is YES, all counters C1 to C14 are cleared (step S3). next,
The start determination flag is turned on, and the other operation mode determination flags are turned off (step S4).

Next, using the data of the cooling water temperature (THW) and the intake air temperature (THA) taken in step S1,
Predetermined start-up fuel temperature calculation coefficient (EKST)
And the starting fuel temperature (THF) based on the following equation (1).
SO) (step S5).

## EQU1 ## THFSO = (THW + THA) × EKST

Here, the equation (1) is derived from the fact that there is a correlation between the fuel temperature at the time of starting, the cooling water temperature, and the intake air temperature. FIG. 8 shows a graph in which changes in fuel temperature, cooling water temperature, and intake air temperature after the engine is stopped are experimentally obtained. As can be seen from this graph, the fuel temperature, like the cooling water temperature and the intake air temperature, decreases with the passage of time after the engine is stopped, and eventually stabilizes at the ambient temperature.

Here, the fuel temperature is always located between the cooling water temperature and the intake air temperature, and it can be seen that there is a correlation between the three temperatures. Therefore, if the coolant temperature and the intake air temperature at the time of starting the engine 1 are known, the fuel temperature at the time of starting can be estimated. For this reason, the optimal calculation formula (Equation 1) is obtained from the experimental results.
Equation). Here, the fuel temperature calculation coefficient (EKST) at the time of starting is set to an optimum value in advance based on experimental results. Next, the starting fuel temperature (THFSO) calculated in step S5 is taken in as the fuel temperature (THFS) (step S6).

When the result of the determination in step S2 is NO, that is, when it is determined that the engine 1 has not been started, it is determined whether or not the engine is in an idling operation mode. Specifically, it is determined whether or not the engine speed (NE) is an idle speed (step S7).
If the result of this determination is YES, the fuel temperature (THF
S) is the idling operation determination fuel temperature (ETHFSIDL)
It is determined whether it is smaller than (Step S8). If the result of this determination is YES, the idle 1 flag is ON
Is determined (step S9).

If the determination result is NO, it indicates that the operation mode has been switched from the other operation mode to the idle 1 operation mode, and all other operation mode continuation counters C2 to C14 are cleared (step S10). Next, the idle 1 determination flag is turned on, and all the other operation mode determination flags are turned off.
F (step S11). Next, the fuel temperature (T) when switching from another operation mode to the idle 1 operation mode is performed.
The value of (HFS) is stored as THFSM (step S12).

Next, the idle 1 operation mode continuation time (C
1) is counted (step S13). Next, using the THFSM stored in step S12, the idle 1 fuel temperature calculation coefficient (EK1), and the idle 1 operation mode duration (C1), the idle 1 is calculated based on the following equation (2). Fuel temperature during operation mode (THFS
1) is obtained (step S14).

Equation 2 THFS1 = THFSM + EK1 × C1

Here, the equation (2) is derived from the fact that the fuel temperature has a correlation between the operation mode and the duration of the operation mode. The idle 1 fuel temperature calculation coefficient (EK1) is obtained in advance by an experiment. , Is set to the optimal value. Next, the fuel temperature (THFS1) in the idle 1 operation mode calculated in step S14 is taken in as the fuel temperature (THFS) (step S15).

If the result of the determination in step S9 is YES, that is, if the idle 1 flag is determined to be ON, it indicates that the idle 1 operation mode is continuing, and in step S13 the idle 1 operation mode The duration (C1) is incremented, and the fuel temperature (THFS1) in the idle 1 operation mode is calculated in step S14.
In step S15, the fuel temperature (THFS) is similarly obtained.

When the result of the determination in step S8 is NO, that is, when it is determined that the fuel temperature (THFS) is higher than the idling operation mode determination fuel temperature (ETHFSIDL), the idle 2 flag is ON. It is determined whether or not (step S16). This determination result is N
In the case of O, it indicates that the mode has been switched from the other operation mode to the idle 2 mode, and all other operation mode continuation counters C1 and C3 to C14 are cleared (step S).
17).

Next, the idle 2 determination mode flag is turned on.
Then, all other operation mode determination flags are turned off (step S18). Next, the value of the fuel temperature (THFS) at the time of switching from the other operation mode to the idle 2 operation mode is stored as the THFSM (step S19).

Next, the idling 2 operation mode continuation time (C
2) is counted (step S20). Next, using the THFSM stored in step S19, the idle 2 fuel temperature calculation coefficient (EK2) and the idle 2 operation mode continuation time (C2), the idle 2 is calculated based on the following equation (3). Fuel temperature during operation mode (THFS
2) is obtained (step S21).

## EQU3 ## THFS2 = THFSM + EK2 × C2

The equation (3) is derived in the same manner as the equation (2), and the idle 2 fuel temperature calculation coefficient (E
K2) is set to an optimum value in advance. Next, the fuel temperature (THFS2) in the idle 2 operation mode calculated in step S21 is taken in as the fuel temperature (THFS) (step S22).

If the result of the determination in step S16 is YES
In other words, when the idle 2 flag is determined to be ON, it indicates that the idle 2 operation mode is continuing, the idle 2 operation mode continuation time (C2) is incremented in step S20, and in step S21. The fuel temperature (THFS2) in the idle 2 operation mode is calculated, and the fuel temperature (THFS) is similarly obtained in step S22.

Here, the fuel temperature calculation coefficients (EK1, EK2) set in the idle operation mode will be described. FIG. 9 is a graph obtained by experimentally obtaining a change in fuel temperature during idling operation.

As can be seen from the graph of FIG. 9, the fuel temperature during the idling operation rises almost linearly with time over a certain temperature, and thereafter tends to stabilize. This is because when the fuel temperature is low, the fuel temperature rises due to radiant heat from the engine and the ambient temperature in the engine room, but after a certain temperature rise,
Since the engine load is small and the calorific value of the engine is small, the ambient temperature in the engine room does not rise and the vehicle tends to be stable. Accordingly, the fuel temperature is stabilized.

As a result, in the present invention, during idling operation, the calculation is divided into two operation modes: low fuel temperature region: idle 1 and high fuel temperature region: idle 2. The idling operation mode determination fuel temperature (ETHFSIDL) is set to a value at which the fuel temperature is substantially stable, and the fuel temperature calculation coefficient (EK1) is at least a value (EK1> EK) larger than the fuel temperature calculation coefficient (EK2).
It is preferable to set to 2). In order to calculate the fuel temperature with high accuracy, each value is set to an optimum value obtained by an experiment in advance.

If the result of the determination in step S7 is NO, that is, if it is determined that the vehicle is not idling, whether the engine speed (NE) is smaller than the operation mode determination engine speed (ENETHFS) or not. It is determined whether or not it is (step S23). This determination result is YES
In this case, it is determined whether the fuel injection amount (QFIN) is smaller than the operation mode determination injection amount (ETHTHFS) (step S24). If the result of this determination is YES, it is determined whether or not the cooling water temperature (THW) at that time is lower than the operation mode determination cooling water temperature (ETHW1L) (step S25).

If the result of this determination is YES, it is determined whether or not the operation mode 11 flag is ON (step S26). If this determination result is NO, it indicates that the operation mode has been switched from another operation mode to the operation mode 11,
Other operation mode continuation counters C1, C2 and C4 to C
14 are all cleared (step S27).

Next, the operation mode 11 determination flag is turned on.
Then, all other operation mode determination flags are turned off (step S28). Next, from other operation modes, operation mode 1
The value of the fuel temperature (THFS) at the time of switching to 1 is set to TH
The memory is stored as the FSM (step S29).

Next, the operation mode 11 duration (C3) is counted (step S30). Next, step S2
Using the THFM stored in step 9, the operation mode 11 fuel temperature calculation coefficient (EK3) and the operation mode 11 duration (C3), the fuel in the operation mode 11 is calculated based on the following equation (4). The temperature (THFS3) is obtained (step S31).

## EQU4 ## THFS3 = THFSM + EK3 × C3

Here, the equation (4) is derived in the same manner as the equation (2), and the operation mode 11 fuel temperature calculation coefficient (EK3) is set to an optimum value in advance. Next, the fuel temperature (THFS3) in the operation mode 11 calculated in step S31 is taken in as the fuel temperature (THFS) (step S32).

Here, the fuel temperature calculation coefficients (EK3 to EK14) set for each traveling operation mode will be described. FIG. 10 is a graph obtained by experimentally obtaining changes in the coolant temperature and the fuel temperature in the low rotation speed and low load range. This figure 1
The relationship between the fuel temperature calculation coefficients will be described with reference to the graph of FIG.

The fuel temperature rise characteristic comprises three linear temperature rise characteristics having different slopes as the coolant temperature rises. Each of the three operation areas is designated as operation mode 1
1, 12, and 13, and EK3, EK4, and EK5 are the fuel temperature calculation coefficients obtained from the respective temperature rise characteristics. Also, in order to calculate with high accuracy, it is preferable that the magnitude of these coefficients is set to at least EK4 larger than EK3 and EK5.

The reason will be described below. It is known that the fuel temperature rises due to heat transfer by radiant heat from the engine, and the magnitude of the radiant heat from the engine is considered to be proportional to the temperature of the cooling water. The temperature rise characteristics of the cooling water temperature are determined by the operating conditions of the engine, the valve opening characteristics of the thermostat, and the like.

In the example of FIG. 10, the temperature of the cooling water rises almost linearly up to about 80 ° C. after the engine is started, and when it exceeds this, the thermostat opens, so that the rate of temperature rise becomes slow and forms a gentle curve. As the cooling water temperature rises, the valve opening lift of the thermostat increases,
It is almost stable at about 90 to 95 ° C.

It is considered that the amount of radiant heat from the engine due to the above-described temperature rise characteristic of the cooling water also has the same characteristic. Here, the fuel temperature is the amount of air or fuel injected in the engine room. Since the temperature of the cooling water rises due to heat transmission through the control member, there is a time delay with respect to the rise of the cooling water temperature. Further, the heating rate is affected by the thermal conductivity of the air and the fuel injection amount control member.

In the example of FIG. 10, the fuel temperature calculation coefficients EK3 and E
Considering the time delay, the portion corresponding to K4 is considered to correspond to a region where the cooling water temperature rises rapidly to about 80 ° C.

The condition of EK4> EK3 is that the region of EK3 is immediately after the start of the engine, and the heat transfer coefficient is low because the air temperature around the engine and the temperature of the fuel injection amount control member are low. EK
This is because the area 4 has a higher air transfer rate and a higher fuel injection amount control member temperature than the area EK3, and therefore has a higher heat transfer coefficient and a faster fuel temperature rise rate.

The reason that EK4> EK5 is satisfied is that the air temperature and the temperature of the fuel injection amount control member are higher and the thermal conductivity is higher in the EK5 region than in the EK4 region. This is because the rate of temperature rise of the fuel is slower than that of EK4 because the temperature rise characteristic of the fuel cell is moderate.

Here, the coolant temperature (ETHW1L, ETHW1H) for judging the operation mode is preferably set to an optimum value by an experiment. However, usually, the value of ETHW1L is close to the thermostat valve opening temperature, and ETHW1
The value of H is near the thermostat full open temperature. These tendencies are determined in other operation mode areas (operation modes 21 to 2).
3, 31-33, 41-43).

In the example shown in FIG. 10, the low rotation speed and low load range are shown. However, these trends are the same in other operation mode ranges (operation modes 21 to 23, 31 to 33 and 41 to 43). Also, it is experimentally known that, as the operation range becomes higher in rotation speed and load, the amount of radiant heat from the engine increases, and the fuel temperature rise rate also increases, so that the fuel temperature calculation coefficient also increases. By setting those coefficient values to optimal values obtained in advance by experiments, the fuel temperature can be calculated with high accuracy.

If the result of the determination in step S26 is YES
In other words, when the operation mode 11 flag is determined to be ON, it indicates that the operation mode 11 is continuing, the operation mode 11 continuation time (C3) is incremented in step S30, and the operation mode 11 The fuel temperature (THFS3) is calculated, and the fuel temperature (THFS) is similarly obtained in step S32.

In the same manner, steps S33 to S11
7, the engine rotation speed (NE), the fuel injection amount (QFIN), the coolant temperature (TH)
From W), each operation mode 12, 13, 21 to 23, 31 to 31
33, 41 to 43 are determined, the continuation time (C4 to C14) of each operation mode is counted, the fuel temperature (THFS4 to THFS14) in each operation mode is calculated, and the calculated time in each operation mode is calculated. Fuel temperature (THFS4 ~
THFS14) is taken in as the fuel temperature (THFS).

Next, steps S6, S15, S22, S
32, S40, S47, S55, S63, S70, S7
9, the fuel temperature (THFS) in each operation mode calculated in S87, S94, S102, S110, and S117 is:
It is determined whether the temperature is lower than the fuel temperature upper limit value (ETHFSMAX) (step S121). This determination result is Y
In the case of ES, the standard fuel temperature (THFSOUT, FIG. 11) preset for each engine speed (NE) is set.
(See (a)) and a fuel temperature difference (ΔTHFS) between the fuel temperature (THFS) (step S123).

Next, based on the fuel temperature difference (ΔTHFS) and the engine speed (NE) obtained in step S123, a corrected injection amount (QATHFS) is obtained from a control characteristic map (see FIG. 11 (b)). Step S12
4). Here, the control characteristic (QATHFS) map is set to an optimum value in advance by experiments or the like.

Next, the final injection quantity (QBASE) is calculated using the base injection quantity (QBASE) calculated from the engine rotation speed (NE) and the accelerator opening (ACCPF) and the corrected injection quantity (QATHFS) obtained in step S124. QFIN) is calculated (step S125).

The result of the determination in step S121 is YE
S, that is, the fuel temperature (TH
When it is determined that the fuel temperature (FS) is equal to or higher than the fuel temperature upper limit (ETHFSMAX), it indicates that the fuel temperature (THFS) has reached the fuel temperature upper limit (ETHFSMAX), and the fuel temperature (THFS) is used as the fuel temperature (THFS). Upper limit (ET
HFSMAX) is taken in (step S122).

Thereafter, the fuel temperature difference (ΔTHFS) is similarly obtained in step S123, and the correction injection amount (QATHFS) is similarly controlled in step S124 by the control characteristic (QATHF).
S) The final injection amount (QFIN) is calculated in the same manner in step S125 by obtaining from the map. These control flowcharts are repeatedly executed from the start of the engine to the stop of the engine.

Here, the control signal based on the final injection amount (QFIN) calculated in step S125 is sent to the fuel injection amount control member 4 of the injection pump 2, so that the fuel injection amount control member 4 (QFIN), and the fuel injection amount is controlled to an optimal value.

[Effects of the Embodiment] As described above, the electronic control injection system for a diesel engine of the present embodiment uses the cooling water temperature, the intake air temperature, the engine rotation speed and the like of the engine 1 without using a fuel temperature sensor. Engine 1
After calculating the operation mode and calculating the continuation time of the operation mode, the fuel temperature is estimated and calculated from the calculated operation mode and the continuation time. The fuel injection amount injected into the sub-combustion chamber 23 of the engine 1 is corrected and controlled on the basis of the engine 1, and the engine 1 and the vehicle 1 run over the entire operating range, such as when the engine 1 is started, during idling, and when the vehicle is running. Thus, appropriate fuel injection amount control can be performed.

Since the fuel temperature is estimated and calculated without providing the fuel temperature sensor in the fuel injection amount control member 4, it is not necessary to mount the fuel temperature sensor on the fuel injection amount control member. Therefore, it is not necessary to secure the mounting space and to process the mounting portion for accurately detecting the temperature. For this reason, it is possible to reduce the product cost of the electronically controlled injection system for a diesel engine and prevent the degree of freedom in mounting design from being impaired.

[Modification] In the present embodiment, the engine speed (NE) and the fuel injection amount (QFI) are determined for each operation mode.
N), using the cooling water temperature (THW) of the engine 1
In addition to those control signals, the vehicle speed, accelerator opening (ACC
PF) and intake air temperature (THA) control signals may be used to determine each operation mode.

In this embodiment, the distribution type fuel injection pump 2 is used as the injection pump, and the electromagnetic spill valve is used as the fuel injection amount control member. However, the line type fuel injection pump is used as the injection pump, and the fuel injection amount control member is used. An actuator that drives a control rack may be used as the control unit.

In this embodiment, an example has been described in which the present invention is applied to an engine 1 without a turbocharger. However, the present invention may be applied to a diesel engine with a turbocharger.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an overall configuration of an electronically controlled injection system for a diesel engine (Example).

FIG. 2 is a control flowchart showing an example of a control program of an ECU (embodiment).

FIG. 3 is a control flowchart illustrating an example of a control program of an ECU (embodiment).

FIG. 4 is a control flowchart showing an example of a control program of an ECU (embodiment).

FIG. 5 is a control flowchart showing an example of a control program of an ECU (embodiment).

FIG. 6 is a control flowchart illustrating an example of a control program of an ECU (embodiment).

FIG. 7 is a control flowchart illustrating an example of a control program of an ECU (embodiment).

FIG. 8 is a graph obtained by experimentally obtaining changes in fuel temperature, cooling water temperature, and intake air temperature after the engine is stopped (Example).

FIG. 9 is a graph obtained by experimentally obtaining a change in fuel temperature during idling operation (Example).

FIG. 10 is a graph obtained by experimentally obtaining changes in cooling water temperature and fuel temperature in a low rotation speed and low load range (Example).

11A is a diagram showing a standard fuel temperature preset for each engine speed, and FIG. 11B is a diagram showing a relationship between the engine speed and the corrected injection amount (Example) ).

FIG. 12 is a control block diagram showing a fuel injection control device for an internal combustion engine according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Diesel engine 2 Injection pump 3 Fuel injection nozzle 4 Fuel injection amount control member 5 Injection timing control member 9 ECU (operation mode determination means, duration calculation means,
Fuel temperature calculation means, injection quantity control means, injection quantity fuel temperature correction quantity calculation means, final injection quantity calculation means) 41 intake temperature sensor (intake temperature detection means) 42 intake pressure sensor (intake pressure detection means) 43 water temperature sensor (cooling) Water temperature detecting means) 44 Crank angle sensor (Crank angle detecting means) 45 Rotation speed sensor (Operating state detecting means, Engine rotational speed detecting means) 101 Operating state detecting means 102 Cooling water temperature detecting means 103 Intake air temperature detecting means 104 Operating mode Determination means 105 Duration calculation means 106 Fuel temperature calculation means 107 Injection amount fuel temperature correction amount calculation means 108 Final injection amount calculation means

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) PE08Z PF01Z PF03Z PF16Z

Claims (8)

[Claims] (A) a fuel injection amount control member for changing a fuel injection amount to the internal combustion engine; (b) operating state detecting means for detecting an operating state of the internal combustion engine; A cooling water temperature detecting means for detecting a temperature of cooling water to be cooled; (d) an intake air temperature detecting means for detecting a temperature of intake air taken into the internal combustion engine; and (e) an operating state detecting means. Estimating a fuel temperature to be injected into the internal combustion engine based on the detected operating state of the internal combustion engine, the cooling water temperature detected by the cooling water temperature detecting means, and the intake air temperature detected by the intake air temperature detecting means. (F) a fuel injection amount calculating means for calculating a fuel injection amount based on the fuel temperature estimated and calculated by the fuel temperature calculating means; and (g) a fuel injection amount calculating means. Fuel calculated by Based on the injection quantity, to control the operating state of the fuel injection quantity control member injection amount control means and the fuel injection control apparatus for an internal combustion engine having a. 2. A fuel injection control device for an internal combustion engine according to claim 1, wherein said fuel temperature calculating means includes an operating state of said internal combustion engine detected by said operating state detecting means, and a cooling water temperature detecting means. Operating mode determining means for determining an operation mode of the internal combustion engine based on the cooling water temperature detected by the detecting means and the intake air temperature detected by the intake air temperature detecting means; and And a duration calculating means for calculating a time during which the operation mode of the internal combustion engine is continued, wherein the operation mode of the internal combustion engine determined by the operation mode determining means and the duration calculated by the duration calculating means are provided. A fuel injection control device for an internal combustion engine, which estimates and calculates a temperature of fuel to be injected into the internal combustion engine based on a duration time. 3. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection amount calculating means corrects the injection according to the fuel temperature estimated and calculated by the fuel temperature calculating means. And a final injection amount calculating means for calculating a final injection amount according to the correction injection amount calculated by the injection amount fuel temperature correction amount calculating means. And a fuel injection control device for an internal combustion engine. 4. The fuel injection control device for an internal combustion engine according to claim 1, wherein the operating state detecting means detects an engine speed of the internal combustion engine. Wherein the internal combustion engine comprises at least one of an injection amount detecting means for detecting a fuel injection amount, a vehicle speed detecting means for detecting a running speed of the vehicle, and an accelerator opening detecting means for detecting an accelerator opening. Engine fuel injection control device. 5. The fuel injection control device for an internal combustion engine according to claim 1, wherein said fuel temperature calculating means operates the internal combustion engine determined by the operation mode determining means. A fuel injection control device for an internal combustion engine, wherein a fuel temperature calculation coefficient is determined according to a mode. 6. The fuel injection control device for an internal combustion engine according to any one of claims 1 to 4, wherein the fuel injection control device opens and closes according to a change in a temperature of a cooling water of the internal combustion engine.
A thermostat that adjusts a flow rate of cooling water flowing to the radiator, wherein the thermostat opens the valve so as to supply cooling water to the radiator when a cooling water temperature of the internal combustion engine rises to a predetermined value or more. And a fuel injection control device for an internal combustion engine. 7. A fuel injection control device for an internal combustion engine according to claim 6, wherein said fuel temperature calculation means determines a fuel temperature calculation coefficient based on a valve opening characteristic of said thermostat. Injection control device. 8. The fuel injection control device for an internal combustion engine according to claim 6, wherein the fuel temperature calculating means is configured to control the fuel temperature in a range from when the thermostat is opened to when the valve lift of the thermostat is stabilized. A fuel injection control device for an internal combustion engine, wherein a temperature calculation coefficient is set to a value larger than a fuel temperature calculation coefficient in another region.