JP2003227379A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct an increase in a proper fuel injection amount in consideration of friction loss of auxiliary machines for a while upon starting or after starting when an engine is heated by a heater during the engine stop. <P>SOLUTION: When the difference between cooling water temperature THW and intake air temperature is judged to be not less than predetermined temperature, although the engine stopping time up to starting is not less than predetermined time, it is judged that the engine is in a state warmed up by a block heater (in the state where friction loss is comparatively large while the auxiliary machines is at low temperature). In this case, for a while upon starting or after starting, the increase amount of fuel injection is corrected by using a correction coefficient of fuel injection of the block heater calculated based on the difference between cooling water temperature THW and intake air temperature THA. Thereby, when the engine is warmed by the heater during the engine stop, the increase of proper fuel injection amount corresponding to the friction loss of the auxiliary machines can be corrected for a while upon starting or after starting. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for an internal combustion engine, which controls a fuel injection amount of the internal combustion engine provided with a heater for warming the internal combustion engine while the internal combustion engine is stopped.

[0002]

2. Description of the Related Art Generally, the lower the engine temperature at start-up, the lower the vaporization characteristic of the injected fuel and the larger the amount of fuel (wet amount) attached to the inner wall surface of the intake port. Less fuel is inhaled. Also, the lower the engine temperature at start-up, the lower the viscosity of the lubricating oil of the engine and accessories (alternator, power steering pump, etc.) and the greater the friction loss. It is necessary to increase the correction amount for increasing the fuel injection amount. Therefore, for example, Japanese Patent Laid-Open No. 9-3031
As disclosed in Japanese Patent Laid-Open No. 75-75, there is a system in which the increase correction amount of the fuel injection amount is increased as the engine temperature (for example, cooling water temperature) at the time of starting or immediately after starting is lower.

In a cold region, a block heater for preventing freezing is provided in a cylinder block of an engine,
There is a system in which the power cord of the block heater is connected to an external power outlet while the engine is stopped to heat the block heater to warm the engine and prevent the engine from freezing.

[0004]

As described above, the block heater is for heating the engine in order to prevent the engine from freezing during cold weather, and the heat generation capacity of the block heater is too small from the viewpoint of reducing power consumption. Since the heat generated by the block heater cannot be increased, most of the heat generated by the block heater is used to prevent the engine from freezing, and the auxiliary machinery around the engine is less affected by the heat generated by the block heater. For this reason, when the engine is warmed by the block heater while the engine is stopped, the temperature of the cooling water at the time of starting and immediately after starting rises due to the heat generated by the block heater, but the temperature of the auxiliary machinery is low near the outside air temperature. It may remain in the state.

However, in the conventional fuel injection control method, the higher the cooling water temperature, the smaller the correction amount for increasing the fuel injection amount. Therefore, in the above-mentioned situation, the temperature of the auxiliary machinery is low,
Despite the relatively large friction loss, the fuel injection amount increase correction amount is set to a small amount based on the cooling water temperature raised by the block heater, and it is necessary to compensate for the friction loss of auxiliary machinery. It is not possible to secure a sufficient increase correction amount of the fuel injection amount. As a result, the engine output torque may be reduced due to a large friction loss of the auxiliary machinery at the time of starting or immediately after the starting, which may lead to deterioration of startability and deterioration of drivability after starting.

The present invention has been made in consideration of such circumstances, and therefore an object thereof is to start the engine for a while after the start when the engine is warmed by a heater while the engine is stopped. Provided is a fuel injection control device for an internal combustion engine, capable of performing an appropriate increase correction of the fuel injection amount in consideration of friction loss of auxiliary machinery during the period, and improving the startability and drivability of the internal combustion engine. To do.

[0007]

In order to achieve the above object, a fuel injection control device for an internal combustion engine according to claim 1 of the present invention is provided with a heater for warming the internal combustion engine while the internal combustion engine is stopped. The engine temperature or a parameter having a correlation therewith (hereinafter collectively referred to as "engine temperature parameter") is detected by the engine temperature parameter detecting means, and the fuel injection amount is calculated based on at least the engine temperature parameter. In the system calculated by the means, the environmental temperature such as the outside air temperature or parameters correlated with the environmental temperature (hereinafter collectively referred to as "environmental temperature parameter") is detected by the environmental temperature parameter detecting means, and the internal combustion engine is operated by the heater. It was determined by the heater warm-up determination means whether or not it was warmed up, and it was determined that the internal combustion engine was warmed up by the heater. Expediently, in which the fuel injection amount were to be increasing correction until a predetermined period of time has elapsed from the starting time and the starting based on the engine temperature parameter and the ambient temperature parameter.

That is, when it is determined that the internal combustion engine is warmed by the heater, the temperature of the internal combustion engine is raised to some extent by the heat generated by the heater. Temperature), and in addition to the engine temperature parameter, the environmental temperature parameter that is relatively close to the temperature of the auxiliary machinery is used as the temperature information of the auxiliary machinery to start or start the engine. Until a predetermined period elapses, an increase correction of the fuel injection amount necessary to compensate the friction loss of the auxiliary machinery is performed. With this configuration, when the internal combustion engine is being warmed by the heater while it is stopped, the appropriate amount of fuel injection can be increased during start-up and for some time after start-up to match the friction loss of the auxiliary machinery. The correction can be performed, the output torque can be prevented from decreasing due to the friction loss of the auxiliary machinery, and the startability and drivability of the internal combustion engine can be improved.

In this case, the internal combustion engine is warmed by the heater based on the difference between the engine temperature parameter and the environmental temperature parameter and / or the stop time of the internal combustion engine before starting. It may be determined whether or not. That is, the difference between the engine temperature parameter and the environmental temperature parameter corresponds to the temperature difference between the temperature of the internal combustion engine and the temperature of the auxiliary machinery, and after the internal combustion engine is stopped, both the internal combustion engine and the auxiliary machinery are sufficiently cooled. In this state, the temperature difference between the temperature of the internal combustion engine and the temperature of the auxiliary machinery (difference between the engine temperature parameter and the environmental temperature parameter) becomes smaller, but when the internal combustion engine is warmed by the heater, this temperature The difference becomes large. Also, since the temperature of the internal combustion engine immediately after the internal combustion engine is stopped is considerably higher than the temperature that can be warmed by the heater, the temperature of the internal combustion engine drops below the temperature that can be warmed by the heater due to natural heat dissipation after the internal combustion engine is stopped. It will take some time to do so. Therefore, if the difference between the engine temperature parameter and the environmental temperature parameter (the temperature difference between the temperature of the internal combustion engine and the temperature of the auxiliary machinery) or the stop time of the internal combustion engine before starting is used, the internal combustion engine is warmed by the heater. It is possible to determine whether or not it is in the established state.

In this case, as in claim 3, it may be determined that the internal combustion engine has not been warmed by the heater when the stop time of the internal combustion engine before starting is less than a predetermined time. That is, if the stop time of the internal combustion engine before starting is short, even if the heater is energized immediately after the stop of the internal combustion engine, the temperature of the internal combustion engine will be higher than the influence of heat generation of the heater during operation of the internal combustion engine. Is greatly affected by the amount of heat stored in the internal combustion engine itself, and since the temperature difference between the temperature of the internal combustion engine and the temperature of the auxiliary machinery is small, when the internal combustion engine is stopped for a short time, By determining that the engine is not warmed by the heater, and correcting the fuel injection amount based on the normal internal combustion engine temperature, etc., without performing the above-described increase correction of the fuel injection amount when the heater is warmed up, The correction amount of the fuel injection amount can be set appropriately.

Further, as in claim 4, it may be determined that the internal combustion engine is not warmed by the heater when the difference between the engine temperature parameter and the environmental temperature parameter is less than or equal to a predetermined value. In other words, when the difference between the engine temperature parameter and the environmental temperature parameter (the temperature difference between the internal combustion engine temperature and the auxiliary machinery temperature) is small, both the internal combustion engine and the auxiliary machinery are sufficiently cooled and are close to the outside air temperature. Therefore, it can be determined that the internal combustion engine is not warmed by the heater.

According to a fifth aspect of the present invention, the temperature of the internal combustion engine when it is not heated by the heater or the temperature of the internal temperature of the internal combustion engine based on the engine temperature parameter when the internal combustion engine is stopped, the environmental temperature parameter, and the stop time of the internal combustion engine. Correlated parameters (These are the "heater off engine temperature parameters" below.
Of the engine temperature is estimated by the heater-off engine temperature estimating means, and this engine temperature parameter when the heater is off is compared with the engine temperature parameter to determine whether or not the internal combustion engine is warmed by the heater. Is also good. That is, the temperature of the internal combustion engine when it is not heated by the heater becomes lower as the environmental temperature such as the temperature of the internal combustion engine when the internal combustion engine is stopped or the outside air temperature becomes lower, and as the internal combustion engine stop time becomes longer, The amount of heat released from the engine increases and the temperature of the internal combustion engine decreases. From such characteristics, the temperature of the internal combustion engine when it is not warmed by the heater (engine temperature parameter when the heater is off) is accurately determined based on the engine temperature parameter when the internal combustion engine is stopped, the environmental temperature parameter, and the stop time of the internal combustion engine. It can be estimated well. If the internal combustion engine is warmed by the heater, the engine temperature parameter at startup will be higher than the engine temperature parameter when the heater is off.
By comparing the engine temperature parameter at the time of starting and the engine temperature parameter at the time of turning off the heater, it can be accurately determined whether or not the internal combustion engine is warmed by the heater.

Further, when it is determined that the internal combustion engine is warmed by the heater as in the sixth aspect of the present invention, based on the engine temperature parameter and the heater-off engine temperature parameter, the engine is started and for a predetermined period from the start. The fuel injection amount may be increased and corrected until the time elapses. In other words, since the heat generated by the heater does not affect the auxiliaries very much, even if the internal combustion engine is being warmed by the heater, the temperature of the auxiliaries will be the same as when the internal combustion engine is not being warmed by the heater. The temperature drops to. Further, when the internal combustion engine is not warmed by the heater, the internal combustion engine and the auxiliary machinery similarly radiate heat according to the stop time of the internal combustion engine to lower the temperature, and the temperature difference between the two decreases. From these relationships, the heater-off engine temperature parameter becomes a parameter for evaluating the temperature of the auxiliary machinery that is less affected by the heat generation of the heater. Therefore, if the engine temperature parameter and the heater-off engine temperature parameter are used, the internal combustion engine It is possible to accurately set the increase correction amount of the fuel injection amount in consideration of both the temperature of 1 and the temperature of the auxiliary machinery.

In general, the internal combustion engine is equipped with a cooling water temperature sensor for detecting the cooling water temperature.
As described above, the cooling water temperature may be detected as the engine temperature parameter. With this configuration, the temperature of the internal combustion engine can be accurately detected from the output of the existing cooling water temperature sensor without adding new sensors.

However, the engine temperature parameter is not limited to the cooling water temperature, and for example, the temperature of the lubricating oil of the internal combustion engine may be detected as the engine temperature parameter, as in claim 8. Alternatively, as in claim 9, the temperature of the fuel may be detected as the engine temperature parameter. Since the temperatures of the lubricating oil and the fuel also change following the changes in the temperature of the internal combustion engine, the temperatures of the lubricating oil and the fuel can also be used as substitute information for the temperature of the internal combustion engine.

Further, as described in claims 10 and 11, the temperature of the intake port or the temperature of the intake valve may be detected as the engine temperature parameter. The temperature of the intake port or intake valve has a great effect on the amount of fuel (wet amount) attached to the intake port or intake valve. Therefore, if the temperature of the intake port or intake valve temperature is used as the engine temperature parameter, the wet amount can be calculated. It is possible to perform the increase correction of the fuel injection amount evaluated accurately.

Further, since the internal combustion engine is generally provided with an intake air temperature sensor for detecting the intake air temperature, the intake air temperature may be detected as the environmental temperature parameter as in claim 12. With this configuration, the environmental temperature can be detected from the output of the existing intake air temperature sensor without adding any new sensor.

Alternatively, as in claim 13, the outside air temperature may be detected as the environmental temperature parameter. Since the outside air temperature is not affected by the temperature of the internal combustion engine, it is possible to detect the environmental temperature with higher accuracy than the intake air temperature.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION << Embodiment (1) >> An embodiment (1) of the present invention will be described below with reference to FIGS.
First, the schematic configuration of the entire engine control system will be described with reference to FIG. An air cleaner 13 is provided at the most upstream portion of an intake pipe 12 of an engine 11 which is an internal combustion engine, and an intake air temperature sensor 14 (environmental temperature parameter detection means) that detects an intake air temperature THA (environmental temperature parameter) is provided in the air cleaner 13. Is provided. Also, air cleaner 1
An air flow meter 15 for detecting the intake air amount GN is provided on the downstream side of 3, and a throttle valve 16 is provided on the downstream side of the air flow meter 15.

Further, a surge tank 17 is provided downstream of the throttle valve 16. The surge tank 17 is provided with an intake manifold 19 for introducing air into each cylinder of the engine 11, and a fuel injection valve 20 for injecting fuel is attached near the intake port of the intake manifold 19 of each cylinder. .

The fuel in the fuel tank 21 is filtered by the filter 22.
After being pumped up by the fuel pump 23 via the fuel pipe 24, it is supplied to the delivery pipe 25 through the fuel pipe 24, and is distributed to the fuel injection valve 20 of each cylinder by the delivery pipe 25. The fuel pipe 24 includes a fuel filter 26 and a pulsation damper 27 for reducing fuel pressure fluctuation (pulsation).
The delivery pipe 25 is provided with a pulsation damper 28 and a fuel temperature sensor 29 for detecting the fuel temperature THF. Further, the fuel pipe 24 has a return pipe 30 for returning excess fuel into the fuel tank 21.
Is connected, and a pressure regulator 31 for adjusting the fuel pressure is provided in the return pipe 30.

On the other hand, a spark plug 32 is attached to the cylinder head of the engine 11 for each cylinder, and the mixture in the cylinder is ignited by the spark discharge of each spark plug 32. Further, a cylinder block of the engine 11 is provided with a cooling water temperature sensor 33 (engine temperature parameter detecting means) that detects a cooling water temperature THW (engine temperature parameter) and a crank angle sensor 34 that detects an engine rotation speed NE, and the wheels are attached. A vehicle speed sensor 35 for detecting the vehicle speed V is provided in the drive system (not shown).

A block heater 36 for preventing freezing is attached to the cylinder block of the engine 11.
The power cord 40 of the block heater 36 is connected to an external power outlet (not shown) to connect the block heater 36.
By heating the engine, it is possible to warm the cooling water and warm the engine 11.

The outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as "ECU") 37. The ECU 37 is mainly composed of a microcomputer, and executes various control programs stored in a built-in ROM (storage medium), so that the fuel injection amount and the ignition of the fuel injection valve 20 are changed according to the engine operating state. The ignition timing of the plug 32 is controlled.

When the ECU 37 controls the fuel injection amount, as shown in FIG. 2, normally, the basic injection time TP calculated based on the intake air amount GN and the engine speed NE is used.
And the invalid injection time TV calculated based on the power supply voltage,
An increase correction coefficient Ks1 at the start calculated based on the cooling water temperature THW at the start or an increase correction coefficient Ks2 after the start, and a water temperature correction coefficient Kthw calculated based on the cooling water temperature THW,
Using the other correction coefficients KK (coefficients including the intake air temperature correction coefficient, the learning correction coefficient, etc.), the final fuel injection time T
Calculate AU. TAU = TP * Ks * Kthw * KK + TV Here, Ks is the increase correction coefficient Ks1 at the time of starting or the increase correction coefficient Ks2 after starting. Then, the ECU 37 controls the pulse width of the injection pulse output to the fuel injection valve 20 to be the final fuel injection time TAU.

On the other hand, at the time of starting, the engine 11 is warmed by the block heater 36 (that is, the engine temperature has risen to some extent, but the auxiliary machines such as the alternator remain at a low temperature close to the outside temperature, and the auxiliary machines are kept). If it is determined that the friction loss of the class is relatively large), the cooling water temperature T
Based on the difference between the HW and the intake air temperature THA, the block heater fuel injection correction coefficient Kh1 at the start or the block heater fuel injection correction coefficient Kh2 after the start is calculated, and the block heater fuel injection correction coefficient Kh1 at the start or after the start The block heater fuel injection correction coefficient Kh2 is used to increase and correct the fuel injection amount. TAU = TP * Ks * Kthw * KK * Kh + TV Here, Kh is the block heater fuel injection correction coefficient Kh1 at the time of starting or the block heater fuel injection correction coefficient Kh2 at the time of starting.

The fuel injection control by the ECU 37 described above is executed according to the fuel injection control program shown in FIGS. 3 and 4. The processing contents of the fuel injection control program shown in FIGS. 3 and 4 will be described below.

The fuel injection control program shown in FIGS. 3 and 4 is executed at a predetermined cycle and serves as a fuel injection amount calculation means in the claims. When this program is started, first in step 101, it is determined whether an ignition switch (not shown) is turned on. If the ignition switch is not turned on,
This program ends as it is.

On the other hand, when the ignition switch is turned on, the routine proceeds from step 101 to step 102, after reading the output signals of the various sensors described above,
In steps 103 and 104, it is determined whether or not the engine 11 is warmed by the block heater 36 depending on whether or not the following conditions are both satisfied. This processing plays a role corresponding to the heater warm-up determination means in the claims.

The engine stop time before starting is longer than a predetermined time (step 103). Here, the predetermined time is the time required for the cooling water temperature THW to drop to near the intake air temperature THA after the engine 11 is stopped. Is set. This prevents the state in which the cooling water temperature THW is high due to the residual heat of the engine 11 from being erroneously determined to be the state in which the block heater 36 has warmed the engine 11 when the engine stop time before starting is short.
This predetermined time may be a fixed value set in advance,
It may be set according to the cooling water temperature THW when the engine is stopped, the intake air temperature THA (outside air temperature), and the like.

The temperature difference between the cooling water temperature THW and the intake air temperature THA is equal to or higher than a predetermined temperature (step 104) That is, when both the engine 11 and the auxiliary machinery are sufficiently cooled after the engine is stopped, the engine 11 Although the temperature difference between the temperature (cooling water temperature THW) and the temperature of the auxiliary machinery (intake air temperature THA) becomes small, this temperature difference becomes large when the engine 11 is warmed by the block heater 36. Therefore, if the engine stop time is long to some extent and the temperature difference between the cooling water temperature THW and the intake air temperature THA is large,
It can be determined that the engine 11 is warmed by the block heater 36.

Conditions above (steps 103, 10)
If one of the conditions 4) is not satisfied, it is determined that the engine 11 is not warmed by the block heater 36, and only the basic increase correction coefficients Ks1 and Ks2 are calculated (steps 105 to 107). And then run
The block heater fuel injection correction coefficients Kh1 and Kh2 are not calculated.

First, at step 105, it is determined whether or not the engine is completed after starting (after starting) depending on whether or not the engine speed NE exceeds the complete explosion determination value. Before starting (when starting)
If so, the process proceeds to step 106 to calculate the basic increase correction coefficient Ks1 at the start according to the cooling water temperature THW at the start using a table or a mathematical expression of the basic increase correction coefficient Ks1 at the start not shown. The table of the basic increase correction coefficient Ks1 at the time of starting is set so that the basic increase correction coefficient Ks1 (basic increase correction amount of the fuel injection amount) increases as the cooling water temperature THW decreases.

After the completion of starting (after starting), step 107
Next, the basic increase correction coefficient Ks2 after the start according to the cooling water temperature THW at the start is calculated using a table or a mathematical expression of the basic increase correction coefficient after the start Ks2 (not shown). The table of the basic increase correction coefficient Ks2 after the start is the cooling water temperature THW.
The basic increase correction coefficient Ks2 (the basic increase correction amount of the fuel injection amount) is set to be larger as the value becomes lower. The increase correction by the basic increase correction coefficient Ks2 after the start is executed only for a predetermined period from the completion of the start. The basic increase correction coefficient Ks2 after the start may be gradually decreased every predetermined time or every predetermined crank angle.

On the other hand, the above steps 103 and 10
In the case of 4, both conditions are satisfied, that is, the temperature difference between the cooling water temperature THW and the intake air temperature THA is determined to be the predetermined temperature or more, although the engine stop time until the start is the predetermined time or more. In this case, it is determined that the engine 11 is warmed by the block heater 36, the basic increase correction coefficients Ks1 and Ks2 are calculated, and the block heater fuel injection correction coefficients Kh1 and Kh2 are calculated (step 108). ~ 110) are executed as follows.

First, in step 108, it is determined whether or not the engine is completed after starting (after starting) depending on whether or not the engine speed NE exceeds the complete explosion determination value. Before starting (when starting)
If so, the process proceeds to step 109, and step 106 is performed.
After calculating the basic increase correction coefficient Ks1 at the time of starting by the same method as described above, the routine proceeds to step 110, where the cooling water temperature THW and the intake air temperature are used by using the table of the block heater fuel injection correction coefficient at the time of starting Kh1 shown in FIG. A block heater fuel injection correction coefficient Kh1 at the time of starting is calculated according to the difference from THA.

After the completion of starting (after starting), step 111
Then, after calculating the basic increase correction coefficient Ks2 after the start in the same manner as in step 107, the process proceeds to step 112, using the table or the formula of the block heater fuel injection correction coefficient Kh2 after the start shown in FIG. The block heater fuel injection correction coefficient Kh2 after the start is calculated according to the difference between the cooling water temperature THW and the intake air temperature THA. The increase correction by the block heater fuel injection correction coefficient Kh2 after the start is executed only for a predetermined period from the completion of the start. The block heater fuel injection correction coefficient Kh2 after the start may be gradually decreased every predetermined time or every predetermined crank angle.

Here, the cooling water temperature THW is determined by the engine 11
It becomes a parameter to evaluate the temperature of. Also, the intake air temperature TH
A is a parameter for evaluating both the engine temperature and the temperature of the auxiliary machinery when the engine 11 is not warmed by the block heater 36.

When the engine 11 is warmed by the block heater 36, the engine temperature has risen to some extent, but the auxiliary components such as the alternator are in a low temperature and the friction loss is relatively large. However, step 1 above
In 09 and 111, the basic increase correction coefficients Ks1 and Ks2 are calculated based on the cooling water temperature THW increased by the block heater 36.
To decrease the basic fuel injection amount increase correction amount. Further, in step 113 to be described later, the water temperature correction coefficient Kthw is reduced based on the cooling water temperature THW raised by the block heater 36, and the increase correction amount of the fuel injection amount is reduced.

Therefore, the table of the block heater fuel injection correction coefficient Kh1 at the time of starting shown in FIG. 5 and the table of the block heater fuel injection correction coefficient Kh2 after the starting shown in FIG. 6 are respectively used for the cooling water temperature THW (instead of the engine temperature). Information) and the intake air temperature THA (information about the temperature of the auxiliary machinery or the substitute information) becomes larger, the block heater fuel injection correction coefficient K becomes larger.
It is set so that h1 and Kh2 are increased and the increase correction amount of the fuel injection amount is increased. As a result, the fuel injection amount increasing correction amount is set to increase as the friction loss increases at low temperatures of the auxiliary machinery.

As described above, the basic increase correction coefficient Ks1,
After calculating Ks2 and the block heater fuel injection correction coefficients Kh1 and Kh2, the process proceeds to step 113 in FIG. 4, and a water temperature correction coefficient Kthw corresponding to the current cooling water temperature THW is calculated using a table or a mathematical expression of the water temperature correction coefficient Kthw (not shown). To calculate. The table of this water temperature correction coefficient Kthw is
The water temperature correction coefficient Kthw increases as the HW decreases, and the increase correction amount of the fuel injection amount increases.

After calculating the water temperature correction coefficient Kthw, step 1
Proceeding to 14, the other correction coefficient KK is calculated. The correction coefficient KK is a correction coefficient including various correction coefficients such as an intake air temperature correction coefficient and a learning correction coefficient.

After that, the routine proceeds to step 115, where the invalid injection time TV corresponding to the response delay time of the fuel injection valve 20 is calculated based on the power supply voltage by a map or the like, and then proceeds to step 116, the intake air amount GN and the engine. Rotation speed NE
Based on, the basic injection time TP is calculated from a map or the like.
After that, the routine proceeds to step 117, and the final fuel injection time TAU is calculated as follows.

Normally (when it is determined that the engine 11 has not been warmed by the block heater 36 at the time of starting), the basic injection time TP, the invalid injection time TV, the basic increase correction coefficients Ks1 and Ks2, the water temperature correction coefficient Kthw, etc. Correction coefficient K
The final fuel injection time TAU is calculated by the following equation using K. TAU = TP * Ks * Kthw * KK + TV Here, Ks = Ks1 at the time of starting and Ks = Ks2 after starting.

On the other hand, when it is determined that the engine 11 is warmed by the block heater 36 at the time of starting, the fuel injection amount is increased and corrected by using the block heater fuel injection correction coefficients Kh1 and Kh2. TAU = TP * Ks * Kthw * KK * Kh + TV Here, Kh = Kh1 at the time of starting and Kh = Kh2 after the starting.

After that, the routine proceeds to step 118, where the pulse width of the injection pulse output to the fuel injection valve 20 is controlled to be the final fuel injection time TAU.

In the embodiment (1) described above, FIG.
As shown in, it is determined that the engine 11 is warmed by the block heater 36 (that is, the engine temperature has risen to some extent, but the auxiliary machinery remains at a low temperature and the friction loss is relatively large). In this case, at the time of starting, the block heater fuel injection correction coefficient Kh1 at the time of starting calculated based on the difference between the cooling water temperature THW (engine temperature substitute information) and the intake temperature THA (auxiliary machine temperature substitute information) The fuel injection amount is increased by using the block heater fuel injection correction coefficient Kh2 after the start, which is calculated based on the difference between the cooling water temperature THW and the intake air temperature THA. As a result, when the block heater 36 warms the engine 11 while the engine is stopped in cold weather, the auxiliary machinery remains at a low temperature and the friction loss is relatively large during the starting or for a while after the starting. In addition, it is possible to perform an appropriate increase correction of the fuel injection amount corresponding to the friction loss, suppress the decrease in engine output torque due to the friction loss of the auxiliary machinery, and improve the startability and drivability of the engine 11. Can be improved.

Further, in the present embodiment (1), when it is determined that the temperature difference between the cooling water temperature THW and the intake air temperature THA is equal to or higher than the predetermined temperature even though the engine stop time until the start is longer than the predetermined time. The engine 11 is equipped with the block heater 3
Since it was decided that it was warmed up in 6,
The engine stop time before starting is short, and the cooling water temperature THW
Is still high, the engine 11 sets the block heater 36
It is possible to prevent the erroneous determination of the warmed state in advance.

<< Embodiment (2) >> Next, FIGS.
The embodiment (2) of the present invention will be described with reference to FIG. In the present embodiment (2), by executing a program in which the processing of FIG. 3 of the fuel injection control programs of FIGS. 3 and 4 described in the above embodiment (1) is replaced with the processing of FIG. The cooling water temperature when 11 is not warmed by the block heater 36 is the estimated cooling water temperature TTHW when the heater is off.
(Heater-off engine temperature parameter), cooling water temperature THW at startup and heater-off estimated cooling water temperature TTH
The engine 11 compares the block heater 36 with W or more.
To determine whether or not it has been warmed up. When it is determined that the engine 11 is warmed by the block heater 36, the block heater fuel injection correction coefficients Kh1 and Kh2 are calculated based on the temperature difference between the cooling water temperature THW and the heater-off estimated cooling water temperature TTHW. , This correction coefficient Kh1, K
The fuel injection amount is increased and corrected using h2.

The processing contents of the program shown in FIG. 8 will be described below. First, in step 201, it is determined whether or not the ignition switch has been switched from ON to OFF, and when the ignition switch has been switched from ON to OFF, the engine 11
It is determined that the engine has been stopped, the process proceeds to step 202, the output signals of various sensors when the engine is stopped are read, and the EC
Store it in the backup RAM (not shown) of U37,
This program ends.

On the other hand, the ignition switch step 2
When it is determined to be “No” in 01, the process proceeds to step 203, and it is determined whether or not the ignition switch is turned on. If the ignition switch is turned on, the process proceeds to step 204 and the various sensors at that time are checked. After reading the output signal, the routine proceeds to step 205, where the heater-off estimated cooling water temperature TTHW when the engine 11 is not warmed by the block heater 36 is calculated. At this time, the heater-off estimated cooling water temperature TTHW is calculated based on, for example, the cooling water temperature when the engine is stopped, the intake air temperature (or outside air temperature) when the engine is stopped and when the engine is started, and the engine stop time.

After the heater-off estimated cooling water temperature TTHW is calculated, the routine proceeds to step 206, where it is determined whether or not the engine 11 is warmed by the block heater 36, depending on whether the cooling water temperature THW is higher than the heater-off estimated cooling water temperature TTHW. judge. This processing plays a role corresponding to the heater warm-up determination means in the claims.

If the cooling water temperature THW is not higher than the heater-off estimated cooling water temperature TTHW, it is determined that the engine 11 is not warmed by the block heater 36, and the basic method is the same as the processing of steps 105 to 107 in FIG. Processing for calculating only the increase correction coefficients Ks1 and Ks2 (step 207)
˜209) is executed and the block heater fuel injection correction coefficients Kh1 and Kh2 are not calculated.

On the other hand, when it is determined in step 206 that the cooling water temperature THW is higher than the heater-off estimated cooling water temperature TTHW, it is determined that the engine 11 is warmed by the block heater 36, A process for calculating the basic increase correction coefficients Ks1 and Ks2 and the block heater fuel injection correction coefficients Kh1 and Kh2 (step 21)
0 to 214) are executed as follows.

First, in step 210, it is determined whether or not the engine has completed the start (after the start) depending on whether or not the engine speed NE exceeds the complete explosion determination value.
Proceeds to step 211 to calculate the basic increase correction coefficient Ks1 at the time of starting, and then proceeds to step 212, using the table of the block heater fuel injection correction coefficient Kh1 at the time of starting shown in FIG. And the block heater fuel injection correction coefficient Kh1 at the time of starting according to the temperature difference between the heater-off estimated cooling water temperature TTHW.

After the completion of starting (after starting), step 213
After calculating the basic increase correction coefficient Ks2 after starting,
Proceeding to step 214, the cooling water temperature THW and the heater-off estimated cooling water temperature TTH are calculated using the table of the block heater fuel injection correction coefficient Kh2 after the start shown in FIG.
The block heater fuel injection correction coefficient Kh2 after the start is calculated according to the temperature difference from W. The increase correction by the block heater fuel injection correction coefficient Kh2 after the start is executed only for a predetermined period from the completion of the start. The block heater fuel injection correction coefficient Kh2 after the start may be gradually decreased every predetermined time or every predetermined crank angle.

The table of the block heater fuel injection correction coefficient Kh1 at the time of starting shown in FIG. 9 and the table of the block heater fuel injection correction coefficient Kh2 after the starting shown in FIG. 10 are respectively the cooling water temperature THW (engine temperature substitute information). As the temperature difference between the heater-off estimated cooling water temperature TTHW (information substitute for the temperature of the auxiliary machinery) increases, the block heater fuel injection correction coefficients Kh1 and Kh2 increase, and the increase correction amount of the fuel injection amount increases. It is set so that the correction amount for increasing the fuel injection amount increases as the friction loss increases at lower temperatures of the auxiliary machinery.

In the embodiment (2) described above, FIG.
As shown in FIG. 1, it is determined that the engine 11 is warmed by the block heater 36 (that is, the engine temperature has risen to some extent, but the auxiliary machinery remains at a low temperature and the friction loss is relatively large). In this case, at the time of starting, at the time of starting, the block heater fuel at the time of starting calculated based on the temperature difference between the cooling water temperature THW (engine temperature substitute information) and the heater off estimated cooling water temperature TTHW (auxiliary machine temperature substitute information). The fuel injection amount is increased and corrected using the injection correction coefficient Kh1, and after the start, the cooling water temperature THW and the heater-off estimated cooling water temperature TT
The fuel injection amount is increased and corrected by using the block heater fuel injection correction coefficient Kh2 after the start calculated based on the temperature difference from HW. As a result, even if the auxiliary machinery is at a low temperature and the friction loss is relatively large during start-up or for a while after the start-up, it is possible to perform an appropriate increase correction of the fuel injection amount commensurate with the friction loss. Therefore, it is possible to suppress a decrease in engine output torque due to friction loss of auxiliary machinery,
It is possible to improve the startability and drivability of the.

In each of the above embodiments (1) and (2),
The cooling water temperature detected by the cooling water temperature sensor 33 was used as an engine temperature parameter for evaluating the engine temperature.
As shown in FIG. 2, an intake port temperature sensor 38 for detecting the temperature of the intake port is installed as an engine temperature parameter detecting means near the intake port of the intake manifold 19, and the intake port temperature detected by the intake port temperature sensor 38 is detected. , May be used as an engine temperature parameter for evaluating the engine temperature.

Alternatively, an intake valve temperature sensor such as a thermistor for detecting the temperature of the intake valve 39 is attached to the intake valve 39 itself or its vicinity as an engine temperature parameter detecting means, and the intake valve temperature detected by the intake valve temperature sensor is detected. , May be used as an engine temperature parameter for evaluating the engine temperature.

Since the intake port temperature and the intake valve temperature have a great influence on the wet amount adhering to the intake port and the intake valve 39, if the intake port temperature and the intake valve temperature are used as the engine temperature parameters, the wet amount can be accurately measured. An increase correction of the evaluated fuel injection amount can be performed.

The fuel temperature detected by the fuel temperature sensor 29 may be used as an engine temperature parameter. Alternatively, in a system including a sensor that detects the temperature of the lubricating oil of the engine 11, the lubricating oil temperature may be used as the engine temperature parameter.

Further, the engine temperature is estimated using two or more parameters of the cooling water temperature, the intake port temperature, the intake valve temperature, the fuel temperature, the lubricating oil temperature, etc., and the estimated engine temperature is used as the engine temperature parameter. You may do it.

In the embodiment (2), the engine 1
Although the cooling water temperature when 1 is not warmed by the block heater 36 is estimated as the engine temperature parameter when the heater is off, the intake port temperature, the intake valve temperature when the engine 11 is not warmed by the block heater 36, The fuel temperature, the lubricating oil temperature, or the engine temperature may be estimated as the engine temperature parameter when the heater is off.

In each of the above embodiments (1) and (2), the intake air temperature detected by the intake air temperature sensor 14 is used as the environmental temperature parameter for evaluating the temperature of the auxiliary machinery at the time of starting and immediately after the starting. In a system including an outside air temperature sensor, the outside air temperature detected by the outside air temperature sensor may be used as the environmental temperature parameter.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire engine control system according to an embodiment (1) of the present invention.

FIG. 2 is a functional block diagram schematically showing a basic configuration of a fuel injection control function of the ECU of the embodiment (1).

FIG. 3 is a flowchart showing a processing flow of a fuel injection control program (first half portion) of the embodiment (1).

FIG. 4 is a flowchart showing a processing flow of a fuel injection control program (second half) of the embodiment (1).

FIG. 5 is a diagram showing a table of a block heater fuel injection correction coefficient Kh1 at the time of starting of the embodiment (1).

FIG. 6 is a diagram showing a table of a block heater fuel injection correction coefficient Kh2 after the start of the embodiment (1).

FIG. 7 is a time chart showing an execution example of the embodiment (1).

FIG. 8 is a flowchart showing a part of a processing flow of a fuel injection control program (first half portion) of the embodiment (2).

FIG. 9 is a diagram showing a table of a block heater fuel injection correction coefficient Kh1 at the time of starting of the embodiment (2).

FIG. 10 is a diagram showing a table of a block heater fuel injection correction coefficient Kh2 after the start of the embodiment (2).

FIG. 11 is a time chart showing an execution example of the embodiment (2).

FIG. 12 is a schematic configuration diagram of an entire engine control system according to another embodiment.

[Explanation of symbols]

11 ... Engine (internal combustion engine), 12 ... Intake pipe, 14 ... Intake temperature sensor (environmental temperature parameter detecting means), 15 ... Air flow meter, 16 ... Throttle valve, 20 ... Fuel injection valve, 29 ... Fuel temperature sensor, 32 ... Spark plug, 33 ...
Cooling water temperature sensor (engine temperature parameter detecting means), 34
… Crank angle sensor, 36… Block heater, 37… E
CU (fuel injection amount calculation means, heater warm-up determination means), 3
8 ... Intake port temperature sensor (engine temperature parameter detecting means), 39 ... Intake valve, 40 ... Power cord.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3G084 AA00 BA13 CA01 CA02 DA05                       DA09 EB08 FA02 FA05 FA07                       FA20 FA33 FA38                 3G301 HA00 JA00 JA03 KA01 KA02                       KA05 LB02 MA11 NA06 NC04                       NE01 PA01Z PA10Z PB01Z                       PE01Z PE03Z PE08Z PF11Z

Claims (13)

[Claims] 1. A heater for warming an internal combustion engine while the internal combustion engine is stopped, and an engine temperature for detecting a temperature of the internal combustion engine or a parameter correlated with the temperature (hereinafter collectively referred to as "engine temperature parameter"). In a fuel injection control device for an internal combustion engine, which comprises a parameter detection means and a fuel injection amount calculation means for calculating a fuel injection amount based on at least the engine temperature parameter, an environmental temperature or a parameter correlated with the environmental temperature Are collectively referred to as “environmental temperature parameters”), and heater warm-up determination means for determining whether or not the internal combustion engine has been warmed by the heater. The amount calculation means is configured to determine whether the internal combustion engine has been warmed by the heater by the heater warm-up determination means. Temperature parameter a fuel injection control apparatus for an internal combustion engine, characterized by increasing correction of the fuel injection quantity until a predetermined period of time has elapsed from the starting time and the starting based on said environmental temperature parameter. 2. The heater warm-up determining means warms the internal combustion engine with the heater based on a difference between the engine temperature parameter and the environmental temperature parameter and / or a stop time of the internal combustion engine until the engine is started. The fuel injection control device for an internal combustion engine according to claim 1, wherein it is determined whether or not the state is the state. 3. The heater warm-up determination means determines that the internal combustion engine is not warmed by the heater when the stop time of the internal combustion engine before starting is a predetermined time or less. 2. The fuel injection control device for the internal combustion engine according to 2. 4. The heater warm-up determination means determines that the internal combustion engine is not warmed by the heater when the difference between the engine temperature parameter and the environmental temperature parameter is a predetermined value or less. A fuel injection control device for an internal combustion engine according to claim 2 or 3. 5. The temperature of the internal combustion engine when it is not warmed by the heater, or a parameter having a correlation therewith, based on the engine temperature parameter when the internal combustion engine is stopped, the environmental temperature parameter, and the stop time of the internal combustion engine. (Hereinafter, these are collectively referred to as "heater off engine temperature parameter")
A heater-off engine temperature estimating means for estimating that the heater warm-up determination means compares the heater-off engine temperature parameter with the engine temperature parameter to determine whether the internal combustion engine is warmed by the heater. The fuel injection control device for an internal combustion engine according to claim 1, wherein the fuel injection control device determines whether or not it is. 6. The temperature of the internal combustion engine when it is not warmed by the heater, or a parameter having a correlation therewith, based on the engine temperature parameter when the internal combustion engine is stopped, the environmental temperature parameter, and the stop time of the internal combustion engine. (Hereinafter, these are collectively referred to as "heater off engine temperature parameter")
A heater off engine temperature estimating means for estimating the fuel injection amount calculating means, wherein the fuel injection amount calculating means determines the engine temperature parameter when the heater warm-up determining means determines that the internal combustion engine is warmed by the heater. 6. The fuel injection control for an internal combustion engine according to claim 1, wherein the fuel injection amount is increased and corrected at the time of starting and until a predetermined period has elapsed since the starting based on the engine temperature parameter when the heater is off. apparatus. 7. The fuel injection control device for an internal combustion engine according to claim 1, wherein the engine temperature parameter detecting means detects a cooling water temperature of the internal combustion engine as the engine temperature parameter. 8. The fuel injection control of an internal combustion engine according to claim 1, wherein the engine temperature parameter detecting means detects a temperature of lubricating oil of the internal combustion engine as the engine temperature parameter. apparatus. 9. The fuel injection control device for an internal combustion engine according to claim 1, wherein the engine temperature parameter detecting means detects a temperature of fuel as the engine temperature parameter. 10. The engine temperature parameter detecting means comprises:
The fuel injection control device for an internal combustion engine according to any one of claims 1 to 6, wherein the temperature of the intake port is detected as the engine temperature parameter. 11. The engine temperature parameter detecting means comprises:
7. The fuel injection control device for an internal combustion engine according to claim 1, wherein the temperature of the intake valve is detected as the engine temperature parameter. 12. The environmental temperature parameter detecting means,
The fuel injection control device for an internal combustion engine according to claim 1, wherein an intake air temperature is detected as the environmental temperature parameter. 13. The environmental temperature parameter detecting means,
The fuel injection control device for an internal combustion engine according to claim 1, wherein an outside air temperature is detected as the environmental temperature parameter.