JP2002030959A - Internal combustion engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the execution of proper control of engine starting during starting of an internal combustion engine having a block heater. SOLUTION: When it is decided ('YES' at SX130) through intercylinder temperature difference generation decision processing that, during starting of an engine, a temperature difference between cylinders is increased (Fh='ON'), average processing (S150) of a cooling water temperature THW and an intake temperature THA is carried out. This processing enables the execution of fuel injection (S180) at a fuel injection amount Q (S160) corresponding to temperature lower than a cooling water temperature THW detected by a cooling water temperature sensor. As described above, when a temperature difference between cylinders is increased by a block heater during starting of the engine, engine starting control responding to temperature lower than the actual cooling water temperature THW is effected. When the temperature difference between the cylinders is not increased, normal engine starting control according to a cooling water temperature THW can be executed. This constitution solves a problem described above.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of an internal combustion engine used in a multi-cylinder internal combustion engine provided with a heater for suppressing cooling of the internal combustion engine by supplying thermal energy to cooling water of the internal combustion engine when the internal combustion engine is stopped. Related to the device.

[0002]

2. Description of the Related Art During a cold start of an internal combustion engine, fuel is increased in accordance with, for example, a cooling water temperature or an intake air temperature in order to maintain rotational stability at or after the start of the engine (Japanese Patent Application Laid-Open No. Sho 63). -38638). As a result, even if the evaporation of the fuel attached to the low-temperature intake port or the like is delayed, the fuel concentration of the air-fuel mixture sucked into the combustion chamber can be prevented from being diluted, and the rotation stability at or after the start is maintained. be able to.

[0003] In a cold region or the like, in order to prevent engine start failure due to extremely low temperature of the internal combustion engine, when the internal combustion engine is stopped, a heater, a so-called block heater, applies heat energy to the cooling water of the internal combustion engine. Has been performed to suppress the temperature of the internal combustion engine from being lowered.

[0004]

However, in the case where the temperature of the internal combustion engine is suppressed by using the block heater while the engine is stopped, the cylinder close to the block heater is sufficient even when the internal combustion engine is stopped. Temperature is maintained at a low temperature, but the temperature may not be sufficiently maintained in a cylinder far from the block heater. Therefore, when trying to execute the above-described fuel increase during cold time by capturing the coolant temperature, a relatively high coolant temperature is detected depending on the mounting position of the coolant temperature sensor. May not be possible.

As described above, at the time of starting the internal combustion engine, there is a problem that the engine control cannot be properly performed in accordance with the value detected by the cooling water temperature sensor due to the operation of the block heater.

An object of the present invention is to provide an internal combustion engine control device which can execute appropriate engine start control at the time of starting an internal combustion engine having the above-described heater.

[0007]

The means for achieving the above object and the effects thereof will be described below. An internal combustion engine control apparatus according to claim 1, wherein the internal combustion engine control is used for a multi-cylinder internal combustion engine having a heater that suppresses a temperature reduction of the internal combustion engine by supplying heat energy to cooling water of the internal combustion engine when the internal combustion engine is stopped. An inter-cylinder temperature difference determining means for determining whether or not a temperature difference between the cylinders due to the operation of the heater is large at the time of starting the internal combustion engine; and The cooling water temperature detecting means to be detected, and when the inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large at the time of starting the internal combustion engine, the cooling water temperature detecting means detects the temperature. Engine control means for performing engine control according to a temperature lower than the cooling water temperature.

[0008] The engine control means, when starting the internal combustion engine,
When the inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large, the engine control is performed according to a temperature lower than the cooling water temperature detected by the cooling water temperature detecting means.

As described above, when the temperature difference between the cylinders is large at the time of starting the internal combustion engine, the engine start control can be performed according to the temperature lower than the cooling water temperature, and the temperature difference between the cylinders can be controlled. If is not large, the engine control means can perform normal engine start control according to the cooling water temperature.

[0010] Therefore, it is possible to execute appropriate engine start control at the time of starting the internal combustion engine provided with the heater. An internal combustion engine control apparatus according to claim 2 is used for a multi-cylinder internal combustion engine provided with a heater that suppresses a low temperature of the internal combustion engine by supplying heat energy to cooling water of the internal combustion engine when the internal combustion engine is stopped. An apparatus, when starting the internal combustion engine, between cylinder temperature difference determining means for determining whether the temperature difference between the cylinders due to the operation of the heater is large, when starting the internal combustion engine, When the inter-cylinder temperature difference judging means judges that the inter-cylinder temperature difference is large, there is provided a leaning suppressing means for suppressing a decrease in fuel vapor concentration in the intake pipe and in the combustion chamber. And

[0011] The leaning suppression means is provided for controlling the fuel vapor concentration in the intake pipe and the combustion chamber when the temperature difference between the cylinders is determined to be large at the time of starting the internal combustion engine. To suppress the decrease. Thus, when the internal combustion engine is started, even when the degree of increase in the fuel supply amount is reduced because the temperature of the cooling water is relatively high due to the operation of the heater, the leaning suppression means can control the inside of the intake pipe and the combustion. In order to suppress a decrease in the fuel vapor concentration in the chamber, the fuel concentration in the intake pipe and the combustion chamber does not become too low.

As described above, when the temperature difference between the cylinders is large at the time of starting the internal combustion engine, an appropriate fuel concentration is obtained by suppressing a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber. I can do it. Further, when the temperature difference between the cylinders is not large, the leaning suppression means does not need to suppress the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber, and in this case, the fuel concentration can be set to an appropriate value. .

Therefore, it is possible to execute appropriate engine start control when starting the internal combustion engine provided with the heater. According to a third aspect of the present invention, in the configuration of the first or second aspect, the inter-cylinder temperature difference determination unit includes:
At the time of starting the internal combustion engine, based on two or more types of detected values representing the temperature of the internal combustion engine or the ambient temperature of the internal combustion engine,
It is characterized in that it is determined whether or not the temperature difference between the cylinders is large.

Whether or not the temperature difference between the cylinders is large when the internal combustion engine is started by the cylinder temperature difference determining means is determined by two or more types of detected values representing the temperature of the internal combustion engine or the ambient temperature of the internal combustion engine. Can be performed based on

That is, for example, when the internal combustion engine is started, if a difference between these detected values is equal to or larger than a reference value, it can be determined that the cylinder-to-cylinder temperature difference is large. .

This makes it possible to execute appropriate engine start control when starting the internal combustion engine having the heater. According to a fourth aspect of the present invention, in the configuration of the third aspect, the detected value is one of a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, an outside air temperature, an intake air temperature, and a hydraulic oil temperature of the transmission. Characterized by two or more.

By comparing two or more of the cooling water temperature of the internal combustion engine, the lubricating oil temperature of the internal combustion engine, the outside air temperature, the intake air temperature, and the operating oil temperature of the transmission, the state between the cylinders is determined. It can be determined that the temperature difference has increased.

This makes it possible to execute appropriate engine start control when starting the internal combustion engine provided with the heater. According to a fifth aspect of the present invention, in the configuration of the third aspect, the detected values are a cooling water temperature of the internal combustion engine, an outside air temperature, and a hydraulic oil temperature of the transmission.

By comparing these states using the three detected values of the cooling water temperature, the outside air temperature, and the hydraulic oil temperature of the transmission, it is more certain that the cylinder-to-cylinder temperature difference has increased. The determination can be made higher.

This makes it possible to execute appropriate engine start control when starting the internal combustion engine having the heater. According to a sixth aspect of the present invention, in the configuration of the third aspect, the detected values are a cooling water temperature of the internal combustion engine, an intake air temperature, and a hydraulic oil temperature of the transmission.

By comparing these states using the three detected values of the cooling water temperature, the intake air temperature and the hydraulic oil temperature of the transmission, it is more certain that the temperature difference between the cylinders has increased. The determination can be made higher.

This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater. According to a seventh aspect of the present invention, in the configuration of the third aspect, the detected values are a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an outside air temperature.

By comparing these states using the three detected values of the cooling water temperature, the lubricating oil temperature of the internal combustion engine, and the outside air temperature, it is more certain that the inter-cylinder temperature difference has increased. Can be increased to make the determination.

This makes it possible to execute appropriate engine start control when starting the internal combustion engine provided with the heater. According to an eighth aspect of the present invention, in the configuration of the third aspect, the detected values are a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an intake air temperature.

By comparing these states using the three detected values of the cooling water temperature, the lubricating oil temperature of the internal combustion engine, and the intake air temperature, it is more certain that the inter-cylinder temperature difference has increased. Can be increased to make the determination.

This makes it possible to execute appropriate engine start control when starting the internal combustion engine having the heater. According to a ninth aspect of the present invention, in the configuration of the third aspect, the detected values are a cooling water temperature and an outside air temperature of the internal combustion engine.

Thus, by comparing these states using the two detected values of the cooling water temperature and the outside air temperature, it can be determined that the temperature difference between the cylinders is large.

This makes it possible to execute appropriate engine start control at the time of starting an internal combustion engine having a heater with a simple configuration. According to a tenth aspect of the present invention, in the configuration of the second aspect, the leaning suppression means is configured to detect the detected cooling in the cold fuel increase process using the cooling water temperature of the internal combustion engine as a parameter. By using the temperature corrected to lower the water temperature, the fuel supply amount is increased to suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber.

As a technique for suppressing a decrease in the fuel vapor concentration in the intake pipe and in the combustion chamber, the leaning suppressing means controls the actual cooling water temperature in the cold fuel increase process using the cooling water temperature of the internal combustion engine as a parameter. Use the temperature corrected for drop.
As a result, the fuel supply amount is increased, and a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed.

Therefore, by utilizing the pre-provided cold fuel increase processing, it is possible to suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber with a simple configuration, and to start the internal combustion engine equipped with the heater. It is possible to execute appropriate engine start control at times.

According to an eleventh aspect of the present invention, in the engine control system according to the second aspect, the leaning suppression means is configured to execute the engine speed reduction executed when the engine speed falls below a reference speed immediately after the engine is started. In the time increase processing, the reference rotation speed is increased to increase the probability of executing the engine speed decrease time increase processing, thereby suppressing a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber.

The leaning suppressing means is a technique for suppressing a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber, and is performed when the engine speed falls below a reference speed immediately after the engine is started. In the above, the reference rotation speed is increased to increase the probability of executing the increase processing when the engine rotation speed decreases. As a result, the fuel supply amount is increased, and a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed.

Therefore, by using the engine speed decrease increasing process provided in advance, it is possible to suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber with a simple configuration, and to reduce the internal combustion engine equipped with the heater. It is possible to execute appropriate engine start control at the time of starting.

According to a twelfth aspect of the present invention, in the configuration of the second aspect, the leanness suppressing means determines that the cylinder-to-cylinder temperature difference is large by the cylinder-to-cylinder temperature difference determining means. In this case, by directly executing the fuel increase processing, a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed.

The leaning suppression means is directly used as a technique for suppressing a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber.
By executing the fuel increase process, a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber may be suppressed. Thus, with a simple configuration, it is possible to suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber, and it is possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater.

According to a thirteenth aspect of the present invention, in the internal combustion engine control device according to the second aspect, the internal combustion engine is an intake port fuel injection type internal combustion engine in which fuel is injected into an intake port. When the inter-cylinder temperature difference determination means determines that the inter-cylinder temperature difference is large, the fuel is injected into the intake port during the intake stroke to suppress a decrease in the fuel vapor concentration in the combustion chamber. Features.

If the internal combustion engine is an intake port fuel injection type internal combustion engine that injects fuel into the intake port, the leaning suppression means uses a method for suppressing a decrease in the fuel vapor concentration in the combustion chamber during the intake stroke. Fuel may be injected into the intake port. As a result, the fuel injected into the intake port immediately enters the combustion chamber together with the intake air, and the amount of fuel adhering to the intake port decreases, so that a decrease in the fuel vapor concentration in the combustion chamber can be suppressed.

This makes it possible to easily suppress a decrease in the fuel vapor concentration in the combustion chamber without relying on an increase in the amount of fuel.
Appropriate engine start control can be performed when starting the internal combustion engine equipped with the heater.

[0039]

[First Embodiment] FIG. 1 shows a schematic configuration of a gasoline engine to which the above-described invention is applied. A gasoline engine (hereinafter simply referred to as an engine) 2 as an internal combustion engine is a V-type eight-cylinder engine mounted on a vehicle for an automobile, and includes two banks 4 and 6 each including four cylinders.

Each of the cylinders 8, 1 provided in the banks 4, 6
0, 12, 14, 16, 18, 20, and 22 have intake ports 8a, 10a, 12a, 14a, 16a, 18a,
Fuel injection valve 2 for injecting fuel toward 20a, 22a
4, 26, 28, 30, 32, 34, 36, 38 are provided. In addition, the intake ports 8a to 8c of the cylinders 8 to 22
22a has intake manifolds 40, 42, 44, 46,
48, 50, 52, and 54 are connected to supply intake air from the surge tank 56 to each of the cylinders 8 to 22. The amount of intake air flowing into the surge tank 56 is adjusted by the opening degree (throttle opening degree TA) of a throttle valve 60 provided in an intake path 58 upstream of the surge tank 56, and each of the cylinders 8 to
During the opening operation of an intake valve (not shown) provided in the cylinder 22, the cylinder is in the intake stroke. The intake path 58 introduces outside air through the air cleaner 62.

The exhaust ports 8b, 10 of the cylinders 8 to 22
b, 12b, 14b, 16b, 18b, 20b, 22b
Are connected to exhaust manifolds 64 and 66. Exhaust gas is exhausted from each of the cylinders 8 to 22 to the exhaust manifolds 64 and 66 by opening an exhaust valve (not shown) in an exhaust stroke. This exhaust gas is purified by a catalyst in a catalytic converter 68 provided in an exhaust pipe 67 where the exhaust manifolds 64 and 66 join, and further discharged to the outside via a muffler (not shown).

Each of the cylinders 8 to 22 has a spark plug 8c, 10
c, 12c, 14c, 16c, 18c, 20c, 22c
Is provided. The ignition plugs 8c to 22c are connected to the igniters 8d, 10d, 12d, 14d,
The 16d, 18d, 20d, and 22d generate a high voltage to generate a spark discharge and ignite an air-fuel mixture in the combustion chamber to burn.

Note that one bank 4 has an engine 2
A block heater 70 for heating the internal cooling water when the operation is stopped is attached to the cylinder block. The block heater 70 is provided to prevent the temperature of the engine 2 from lowering when the vehicle is left in a garage for a long time in a cold region with the engine 2 stopped. A heating wire is provided inside the block heater 70, and heat is generated by using electric power from an AC power supply 72 in a general home by inserting a plug 70a into an outlet 72a. When the vehicle is running, the plug 70a is connected to the outlet 7
Remove from 2a.

In the first embodiment, the block heater 70
Are arranged near the cylinder 8 at the end of the bank 4. At this position, the cooling water existing in the water jacket of the bank 4 is heated, and thermal energy is supplied to the entire bank 4 and the other banks 6 by convection of the cooling water.

An intake air temperature sensor 74 is provided in the intake passage 58 to detect the temperature of the intake air (intake air temperature THA) flowing into the intake passage 58 via the air cleaner 62. An intake pressure sensor 76 is provided in the surge tank 56,
The intake pressure PM in the surge tank 56 is detected.

The opening degree TA of the throttle valve 60 provided in the intake path 58 is determined by a throttle opening degree sensor 75.
Has been detected. An engine speed sensor 78 that generates an output pulse every time the crankshaft rotates 10 ° is provided near the crankshaft (not shown). Further, a cylinder discrimination sensor (also referred to as a cam angle sensor) 80 that generates an output pulse when a specific cylinder reaches the intake top dead center from rotation of an intake camshaft (not shown) is provided.

Further, a cooling water temperature sensor 82 for detecting a cooling water temperature THW is provided near the cylinder 8 of the bank 4. The exhaust pipe 67 is provided with an air-fuel ratio sensor 84 that detects the air-fuel ratio A / F of the air-fuel mixture based on the exhaust components.

The signals from the intake air temperature sensor 74, the throttle opening sensor 75, the intake pressure sensor 76, the engine speed sensor 78, the cylinder discriminating sensor 80, the cooling water temperature sensor 82 and the air-fuel ratio sensor 84 are shown in the control system block of FIG. Electronic control unit shown in the figure (hereinafter referred to as "ECU")
Processed at 90.

The ECU 90 is composed of a digital computer, and is connected to each other via a bidirectional bus 90a.
It includes a U90b, a ROM 90c, a RAM 90d, a backup RAM 90e, an input circuit 90f, and an output circuit 90g.

The signals from the sensors 74 to 84 described above are taken into the ECU 90 via the input circuit 90f and processed. For example, the current crank angle is calculated from the output pulse of the cylinder discrimination sensor 80 and the output pulse of the engine speed sensor 78, and the engine speed NE is calculated from the frequency of the output pulse of the engine speed sensor 78.

The vehicle also has an AT oil temperature sensor 92 for detecting the temperature of an operating oil (AT operating oil temperature ATH) of an automatic transmission (not shown), and an outside air temperature THE as an ambient temperature around the engine 2. An outside air temperature sensor 93 for detecting, an accelerator opening sensor 94 for detecting an amount of depression of an accelerator pedal (not shown) (hereinafter, referred to as "accelerator opening") ACCP, and other sensors;
The operating state and the atmospheric state of the engine 2 are detected.

The ECU 90 determines whether each of the fuel injection valves 24 to
38, a motor 6 for driving the throttle valve 60
0a (DC motor or step motor), igniters 8d to 22d, starter motor 96, and other actuators are driven via output circuit 90g.

Thus, during the air-fuel ratio feedback control by the ECU 90, the fuel injection valves 24 to 3 are adjusted to the target air-fuel ratio in accordance with the output of the air-fuel ratio sensor 84.
The fuel injection amount injected from the nozzle 8 is adjusted. Further, for example, when it is necessary to increase the fuel concentration according to the operating state of the engine 2 such as at a cold time or a high load, the fuel concentration is made higher than the target air-fuel ratio to improve the flammability. In addition, the catalyst converter 68 is prevented from being melted by the catalyst at a high temperature.

The ECU 90 responds to the accelerator opening ACCP detected by the accelerator opening sensor 94.
The opening of the throttle valve 60 is adjusted via a throttle valve driving motor 60a. At this time, the throttle opening TA detected by the throttle opening sensor 75
However, the feedback control is performed so that the target opening degree corresponds to the accelerator opening degree ACCP.

Next, a fuel injection amount control process performed by the ECU 90 from the start of the engine 2 after the start will be described with reference to the flowchart of FIG. This process is started when the ignition switch is turned on, and is periodically executed for each preset crank angle. Each processing step in each flowchart described below is represented by “S で”.

When the fuel injection amount control process is started, first, the engine speed NE, the intake pressure PM, the cooling water temperature TH
W, intake air temperature THA, AT hydraulic oil temperature ATH, outside air temperature TH
E, the engine operating state such as the air-fuel ratio A / F is stored in RAM 90d
(S110).

Next, it is determined whether or not the engine is starting (S12).
0). Whether or not the engine has started is determined by determining whether the engine speed NE of the engine 2 that has started driving by cranking is equal to the start completion reference engine speed Ns.
If it has not risen, it is determined that it is the time of starting (S
120 (“YES” at 120), the inter-cylinder temperature difference occurrence flag Fh obtained in the after-cylinder temperature difference occurrence determination processing described
N ”is determined (S130).

Here, if Fh = "OFF" (S1)
30 "NO"), the temperature variable T is set to the current cooling water temperature THW.
Is set (S140). On the other hand, if Fh = “ON” (“YES” in S130), the current cooling water temperature THW and intake air temperature T
An average value with the HA is set (S150).

[0059]

T ← (THW + THA) / 2 [Equation 1] After step S140 or step S150, based on the temperature variable T, the map showing the tendency in FIG. It is calculated (S160).

For example, when Fh = “OFF”, if the current coolant temperature THW is Tx, T = Tx in step S140, so that the value of the fuel injection amount Q = Qx is set as shown in FIG. Is done. However, when Fh = “ON”, if the current cooling water temperature THW is Tx and the intake air temperature THA is Ty, as shown in FIG.
By 150, T = (Tx + Ty) / 2 (= Tm). Therefore, the fuel injection quantity Q = ΔQ larger than Qx
The value of Qm is set.

Then, the fuel injection amount Q is stored as a starting fuel injection amount storage value Qa (S170). Then, the fuel injection amount Q is set as the valve opening time of the fuel injection valves 24 to 38 (S180), and the present process is ended once.

On the other hand, if it is not the time of starting ("N" in S120)
O "), and then it is determined whether or not the start is completed (S19).
0). Before cranking ("N" in S190
O "), the process is once ended as it is.

If the engine 2 is started by cranking and the engine speed NE has once increased to the start completion reference speed Ns, the start is completed ("YES" in S190). Number NE and intake pressure PM
From the map shown in FIG.
BS is calculated (S200). This basic fuel injection amount Q
BS indicates the fuel injection amount for the mixture to reach the stoichiometric air-fuel ratio under the conditions of the engine speed NE and the intake pressure PM.

Next, based on the current cooling water temperature THW,
From the map showing the trend in FIG. 6, the fuel injection amount cold correction coefficient K
q is calculated (S210). The fuel injection amount cold correction coefficient Kq (Kq> 0) is a coefficient for increasing the fuel injection amount required at the time of cold.

Next, as shown in the following equation 2, the post-start fuel injection amount Qb is calculated (S220).

[0066]

Qb ← QBS · (1.0 + Kq + FAF + KG) + Kz (Equation 2) where FAF is an air-fuel ratio feedback coefficient for controlling the air-fuel ratio to a target air-fuel ratio (here, stoichiometric air-fuel ratio), and K
G represents the learning value, and Kz represents other correction values.
When the air-fuel ratio feedback control has not been started immediately after starting, for example, FAF = "0".

Next, it is determined whether or not the starting fuel injection amount storage value Qa stored at the time of starting is larger than the post-starting fuel injection amount Qb (S230). Immediately after the start is completed,
If a> Qb (“YES” in S230), the starting fuel injection amount storage value Qa is slightly reduced by the gradual decrease process fd (Qa) (S240). Then, the starting fuel injection amount storage value Qa after the gradual decrease is set as the fuel injection amount Q (S2).
50) The fuel injection amount Q is set as the valve opening time of the fuel injection valves 24 to 38 (S180), and the present process is ended once.

As long as Qa> Qb holds ("Y" in S230)
ES "), the gradually reduced starting fuel injection amount stored value Q
a (S240) is set to the fuel injection amount Q (S2
50), the fuel injection amount Q gradually decreases.

If Qa ≦ Qb (“NO” in S230), the starting fuel injection amount storage value Qa is cleared (S260), and the post-starting fuel injection amount Qb is set to the fuel injection amount Q. (S270). Then, the fuel injection amount Q in which the post-start fuel injection amount Qb is set is changed to the fuel injection valves 24 to 3.
8 (S180), and the process is once terminated.

Thus, thereafter, the post-start fuel injection amount Qb
Is set as the valve opening time of the fuel injection valves 24-38. Next, an inter-cylinder temperature difference occurrence determination process for setting the inter-cylinder temperature difference occurrence flag Fh will be described with reference to FIG. This processing is repeatedly executed at a fixed time period.

When the process is started, it is first determined whether or not the engine is at the start (S310). The content of this determination is the same as the processing in step S120 of the fuel injection amount control (FIG. 3). If it is not the start time ("NO" in S310), then "OFF (incomplete)" is set to a determination completion flag Fb indicating whether or not the determination of the occurrence of the cylinder-to-cylinder temperature difference has been completed (S3).
20), end this process once.

At the time of startup ("YE" in S310)
S)), it is determined whether the determination completion flag Fb is “OFF” (S330). If Fb = “ON (completion)” (“NO” in S330), the present process is temporarily terminated as it is, but initially Fb = “OFF” (S3).
30 "YES"), and then the current cooling water temperature THW becomes 1
It is determined whether the temperature is higher than 0 ° C. (S340).

If THW> 10 ° C. (“Y” in S340)
ES "), and it is determined whether or not the outside air temperature THE is lower than -20C (S350). If THE <−20 ° C. (“YES” in S350), it is then determined whether or not the AT operating oil temperature ATH is lower than −20 ° C. (S360). A
If TH <−20 ° C. (“YES” in S360), “ON” is set in the inter-cylinder temperature difference occurrence flag Fh (S360).
370). If the outside temperature THE and the AT hydraulic oil temperature ATH are both lower than −20 ° C. in spite of the fact that the cooling water temperature THW is at a certain level, the block is performed until immediately before the start. It is determined that heater 70 has been activated. That is, the fact that the operation of the block heater 70 causes a temperature difference between the cylinders 8 and 22 of the engine 2 to be a problem if the engine 2 is controlled with the detection value of the cooling water temperature sensor 82 as it is. Is shown.

On the other hand, if the cooling water temperature THW is equal to or lower than 10 ° C. (“NO” in S340), the outside air temperature THE becomes −20 ° C.
If this is the case ("NO" in S350), if the AT operating oil temperature ATH is -20 ° C or higher ("N" in S360)
O ”),“ OFF ”is set in the inter-cylinder temperature difference occurrence flag Fh (S380). That is, the temperature difference between the cylinders 8 to 22 of the engine 2 is such that there is a problem even if the cooling water temperature THW is used as it is for control, even if the block heater 70 is not operating or the block heater 70 is operating. Indicates that no event has occurred.

When the processing in step S370 or S380 is completed, "ON" is set in the determination completion flag Fb (S385), and the processing is temporarily terminated. As described above, only once at the time of starting, steps S340 to S340 are performed.
The determination in S360 is made, and the cylinder temperature difference occurrence flag F
h is set to either “ON” or “OFF”.

Based on the thus set inter-cylinder temperature difference occurrence flag Fh, in the above-described fuel injection amount control processing (FIG. 3), the cooling water temperature THW is used as it is at the time of starting (S140), or the cooling water temperature THW is used. And intake air temperature THA
Is determined (S150).
30)

An example of the control by the above-described processing is shown by a solid line in the timing charts of FIGS. In the example of FIG. 8, a state in which the vehicle is left in the garage for a long time by turning on (ON) the block heater 70 in a cold region with the engine 2 stopped and the outside air temperature THE becomes −30 ° C. ing. While the engine 2 is stopped, the cooling water temperature THW becomes 20 ° C. due to the heat generated by the block heater 70.
, But the intake air temperature THA is
The hydraulic oil temperature ATH has dropped to -25 ° C.

To start the engine 2, at time t 0, the plug 70 a of the block heater 70 is disconnected from the outlet 72 a of the AC power supply 72 (OFF), and the power supply to the block heater 70 is stopped. Next, at time t1, the ignition key is turned to start cranking by the starter. At this time, the cylinder temperature difference occurrence flag Fh
Is set to “ON”, the fuel injection amount Q is determined by the cooling water temperature THW (= 20 ° C.) and the intake air temperature THA (= −20 ° C.).
Is set based on 0 ° C. which is the average value of As a result, a fuel injection amount Q of an amount corresponding to THW = 0 ° C. is injected from the fuel injection valves 24 to 38, and the combustion chamber is brought into a mixture state required for stable combustion.

Therefore, the engine speed NE sharply increases and exceeds the start completion reference speed Ns at time t2. This completes the start. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to execution of the idle speed feedback control and the air-fuel ratio feedback control.

Note that the cooling water temperature THW (= 2
0 ° C.) alone, when the fuel injection amount Q is determined, as shown by the broken line, the fuel injection amount Q becomes considerably smaller than the amount required for stable combustion, making it difficult to start the engine 2 or However, stable rotation cannot be obtained, and the possibility of engine stall increases.

In the example of FIG. 9, the vehicle is left in the garage without turning on the power to the block heater 70 (OFF) in a cold region with the engine 2 stopped, and the outside air temperature THE is -25 ° C.
This shows the case where the cooling water temperature THW has dropped to -10 ° C, the intake air temperature THA has dropped to -15 ° C, and the AT operating oil temperature ATH has dropped to -22 ° C.

In this situation, the ignition key is turned at time t11 to start cranking by the starter. At this time, “OF” is set in the cylinder temperature difference occurrence flag Fh.
F ”is set, the fuel injection amount Q becomes the cooling water temperature TH
It is set based on W (= −10 ° C.). As a result, a fuel injection amount Q of an amount corresponding to the value of the cooling water temperature THW (= -10 ° C.) itself is injected from the fuel injection valves 24 to 38, and the combustion chamber becomes a mixture state required for stable combustion. .

Therefore, the engine speed NE rapidly rises and exceeds the start completion reference speed Ns at time t12, whereby the start is completed. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to execution of the idle speed feedback control and the air-fuel ratio feedback control.

In the structure of the first embodiment, the cooling water temperature sensor 82 corresponds to the cooling water temperature detecting means. Steps S340 to S360 correspond to steps S130 and S150 to S18 in the processing as the cylinder temperature difference determination means.
0 corresponds to processing as engine control means.

According to the first embodiment described above, the following effects can be obtained. (I). In the fuel injection amount control process (FIG. 3), the engine 2
If the temperature difference between cylinders is determined to be large in the inter-cylinder temperature difference occurrence determination process (FIG. 7) (“YES” in S130), the cooling water temperature THW and the intake air temperature T
An averaging process with the HA (S150) is performed. Thus, fuel injection can be performed with the fuel injection amount Q corresponding to a temperature lower than the cooling water temperature THW detected by the cooling water temperature sensor 82.

As described above, when the temperature difference between the cylinders is large when the engine 2 is started, the engine start control according to the temperature lower than the actual cooling water temperature THW can be performed. When the inter-temperature difference is not large, normal engine start control according to the cooling water temperature THW itself can be performed.

For this reason, when starting the engine 2 having the block heater 70, it is possible to execute appropriate engine start control. (B). In the first embodiment, in particular, the cooling water temperature THW,
Using the three detected values of the outside air temperature THE and the hydraulic oil temperature ATH of the automatic transmission and comparing these states as in steps S340 to S360, it is detected that the cylinder-to-cylinder temperature difference is large. .

Although the outside air temperature THE and the AT working oil temperature ATH are lower than -20.degree.
It is almost certain that HW> 10 ° C. is a state caused by the action of the block heater 70, whereby it is possible to determine with high certainty that a large temperature difference between cylinders is large. .

(C). When it is determined that the cylinder-to-cylinder temperature difference is large, an appropriate fuel injection amount Q is obtained by using the average value of the cooling water temperature THW and the intake air temperature THA by using the normal fuel increase processing during cold operation. Can be obtained. With such a simple configuration, the effects (a) and (b) can be produced, and the manufacturing cost can be reduced.

[Second Embodiment] In a second embodiment, a fuel injection amount control process shown in FIG. 10 is executed instead of the fuel injection amount control process (FIG. 3) of the first embodiment. Further, in addition to this, the rough fuel increase process shown in FIG.
And a post-start fuel injection timing setting process shown in FIG. The other configuration is the same as that of the first embodiment unless otherwise described.

Next, the fuel injection amount control process (FIG. 10) will be described. In the fuel injection amount control process (FIG. 10),
Steps S510, S520, S570-S670
The processing is the same as the processing in steps S110, S120, and S170 to S270 in the fuel injection amount control processing (FIG. 3) of the first embodiment. In the second embodiment, the processing after it is determined in step S520 that the engine is at the start is different from that of the first embodiment.

That is, when it is determined that the engine is at the start ("YES" in S520), the map immediately showing the tendency shown in FIG. 4 (Embodiment 1) based on the cooling water temperature THW is shown in FIG.
The fuel injection amount Q at the time of starting is calculated (S56).
0). Then, the fuel injection amount Q is set as the starting fuel injection amount storage value Qa (S570), and the fuel injection amount Q is further set.
Is set as the valve opening time of the fuel injection valves 24-38 (S
580), and the process is once ended.

Therefore, the fuel injection amount control process (FIG. 1)
In 0), the processing does not change depending on whether or not the inter-cylinder temperature difference occurrence flag Fh is “ON”. Instead, in the second embodiment, a countermeasure is executed when the inter-cylinder temperature difference occurrence flag Fh is “ON” by using the poor fuel increase process (FIG. 11).

Next, the rough fuel increase process (FIG. 11) will be described. This process is a process that is repeatedly executed in a fixed time cycle. When the present process is started, first, it is determined whether the start is completed (S710). If it is before or at the time of startup ("NO" in S710), "OFF" is set for the rough fuel increase processing completion flag Fy (S720), and this processing is once ended.

If the engine 2 starts to start by cranking and the engine speed NE has increased to the start completion reference speed Ns, the start is completed ("Y" in S710).
ES "), then, it is determined whether or not the inferior fuel increase processing completion flag Fy is" OFF "(S730). Fy = “O
If “N”, the present process is temporarily terminated as it is, but first, since Fy = “OFF” (S730), it is set in the cylinder-to-cylinder temperature difference occurrence determination process (Embodiment 1: FIG. 7). It is determined whether the inter-cylinder temperature difference occurrence flag Fh is “ON” (S740).

Here, if Fh = "OFF" (S7)
("NO" at 40), in order to determine the use of poor fuel from the degree of decrease in the engine speed immediately after the start, a decrease determination engine speed NEL is determined based on the cooling water temperature THW by using a map A showing a tendency by a solid line A in FIG. Is calculated (S750). Next, it is determined whether or not the value of the engine speed NE at the time of lowering falls below the decrease determination speed NEL (S760). If NE ≧ NEL when descending (“NO” in S760),
Next, it is determined whether the time from the completion of the start is a state before the elapse of the determination standby time S (second) (S780). If the determination standby time S has not elapsed ("YES" in S780), the present process is temporarily terminated.

In the state of NE ≧ NEL at the time of descending (S
If “NO” at 760), the determination standby time S has elapsed (S
("NO" at 780), since the decrease in the engine speed NE is small, it can be determined that the fuel injected from the fuel injection valves 24-38 is not a poor fuel. Therefore, next, "ON" is set to the rough fuel increase processing completion flag Fy (S790), and this processing is once ended. After that, Fy =
Since it is "ON"("NO" in S730), the substantial processing of the rough fuel increase processing ends.

Before the elapse of the determination standby time S (S780)
Is "YES"), and when NE <NEL at the time of descending is satisfied (S7)
At 60, “YES”), it can be determined that poor fuel is used because the degree of decrease in the engine speed NE is large. Therefore, next, a map a showing a tendency by a solid line a in FIG.
Then, the starting fuel injection amount storage value Qa is updated based on the cooling water temperature THW (S770). As described above, in order to improve the combustibility of the inferior fuel, that is, the fuel which is hardly volatilized, the fuel injection amount control processing (FIG. 10) calculates (S560, S570) and gradually decreases the processing (S640).
Is executed to update the starting fuel injection amount storage value Qa used in the above to a value that is as large as necessary according to the cooling water temperature THW.

By updating the starting fuel injection amount storage value Qa to a large value in this way, especially in the gradual decrease process (S640) of the fuel injection amount control process (FIG. 10), the starting fuel value updated to the large value is used. The process of gradually reducing the fuel injection amount from the fuel injection amount storage value Qa continues.

When the start-time fuel injection amount storage value Qa is updated (S770), "ON" is set to the rough fuel increase processing completion flag Fy (S790), and this processing is ended once. Thereafter, since Fy = “ON”, (S
("NO" in 730), the substantial processing of the poor fuel increase processing ends.

On the other hand, if Fh = “ON” (S740)
"YES"), a state in which a cylinder-to-cylinder temperature difference has occurred because the block heater 70 was operating when the engine 2 was stopped. For this reason, next, in order to execute the fuel injection amount increase utilizing the decrease in the engine speed immediately after the start, a decrease determination rotation based on the cooling water temperature THW is performed by using a map B showing a tendency indicated by a solid line B in FIG. The number NEL is calculated (S800). As can be seen from FIG. 12, the decrease determination rotational speed NEL calculated from the map B is designed to be set to a higher rotational speed than in the case of the map A for determining the poor fuel described above.

Next, it is determined whether or not the value of the engine speed NE at the time of lowering has fallen below the decrease determination speed NEL (S810). If NE ≧ NEL when descending (S81
0 and “NO”), and then it is determined whether or not the time from the completion of the start is a state before the elapse of the determination standby time S (second) (S78)
0). If the determination standby time S has not yet elapsed ("Y" in S780).
ES "), and this process is temporarily ended as it is.

In the state of NE ≧ NEL at the time of descending (S
If “NO” at 810), the determination standby time S has elapsed (S
780 (“NO”), it can be determined that the cylinder-to-cylinder temperature difference is such that there is no practical problem. Therefore, next, "ON" is set to the rough fuel increase processing completion flag Fy (S79).
0), the process is once ended. Thereafter, Fy = “ON”
(“NO” in S730), the substantial processing of the measure for the temperature difference between the cylinders ends.

Before the elapse of the determination standby time S (S780)
Is “YES”), when NE <NEL at the time of descending is satisfied (S8)
10, "YES"), it can be determined that it is necessary to take measures against the cylinder-to-cylinder temperature difference because the decrease in the engine speed NE is large.
Therefore, next, the start-time fuel injection amount storage value Qa is updated based on the coolant temperature THW using the map b showing the tendency by the solid line b in FIG. 13 (S820). That is, the fuel injection amount control processing (FIG.
0) (S560, S570), and updates the starting fuel injection amount storage value Qa used in the gradual decrease process (S640) to a value as large as necessary according to the cooling water temperature THW. Execute.

Thus, especially in the gradual decrease process (S640) of the fuel injection amount control process (FIG. 10), the process of gradually decreasing the fuel injection amount from the starting fuel injection amount storage value Qa that has increased is continued.

When the start-time fuel injection amount storage value Qa is updated in this way, "ON" is set to the inferior fuel increase processing completion flag Fy (S790), and the present processing is ended once. Thereafter, since Fy = “ON” (“NO” in S730), the substantial processing for the measure for the temperature difference between cylinders ends.

Next, a post-start fuel injection timing setting process (FIG. 1)
4) will be described. This process is a process that is repeatedly executed in a fixed time cycle. When the process is started, first, it is determined whether or not the engine is at the start (S910). If cranking is being performed ("YES" in S910), "OFF" is set for the post-start fuel injection timing setting completion flag Fz (S91).
5).

Then, it is determined whether time C has elapsed (S920). The time C represents a continuation reference time of the intake synchronous injection setting (S930) performed at the time of starting. At first, since the fuel injection itself has not been executed yet, time C has not elapsed ("NO" in S920), and then intake synchronous injection is set (S930). Here, the intake synchronous injection indicates a fuel injection mode in which fuel is injected from the fuel injection valves 24 to 38 toward the intake ports 8a to 22a in the intake stroke.

Thus, the present processing is once ended. As a result, fuel is injected from the fuel injection valves 24 to 38 in the intake stroke, so that the injected fuel is immediately sucked into the combustion chamber together with the intake air.

At the start, until the time C elapses ("NO" in S920), the intake synchronous injection is set (S9).
30) continues. When the time C has elapsed (S9)
20 (“YES”), the intake asynchronous injection is set (S
940). Here, the intake asynchronous injection indicates a fuel injection mode in which fuel is injected from the fuel injection valves 24 to 38 toward the intake ports 8a to 22a before an intake stroke such as a compression stroke, an expansion stroke, or an exhaust stroke. .

Thus, the present processing is once ended. As a result, fuel is injected from the fuel injection valves 24-38 before the intake stroke, so that the intake ports 8a-22
The fuel that has become the vapor after adhering to a is sucked into the combustion chamber together with the intake air in the intake stroke.

When the start is completed ("NO" in S910), it is determined whether or not the start-time fuel injection amount storage value Qa has been updated in step S770 or step S820 of the rough fuel increase process (FIG. 11). Is determined (S9
50). If the starting fuel injection amount storage value Qa has not been updated in step S770 or step S820 (“NO” in step S950), that is, step S760 or step S810 in the rough fuel increase process (FIG. 11).
In any of the cases, if it is determined that NE ≧ NEL at the time of descent, intake asynchronous injection is set (S94).
0) This process is temporarily terminated.

On the other hand, step S770 or step S770
If the start-time fuel injection amount storage value Qa has been updated at 820 ("YES" at S950), that is, even if either step S760 or step S810 of the poor fuel increase process (FIG. 11), the value at the time of the descent is determined. NE <NEL
Is determined, it is then determined whether or not the post-start fuel injection timing setting completion flag Fz is "OFF" (S96).
0).

If Fz = “ON” (“N” in S960)
O)), the asynchronous intake injection is set (S940), and the process ends once. However, since Fz = “OFF” at first (“YES” in S960), the time D elapses. It is determined whether or not there is (S970). This time D
Represents a continuation reference time of the intake synchronous injection setting (S930) executed after “YES” is determined in step S950.

If the time D has not elapsed ("NO" in S970), the intake synchronous injection is set (S9).
30). Thus, the present process is temporarily terminated. As a result, fuel is injected from the fuel injection valves 24 to 38 in the intake stroke.

If the time D has elapsed (“YE” in S970)
S)), then, “ON” is set to the post-start fuel injection timing setting completion flag Fz (S980), intake asynchronous injection is set (S940), and the present process is ended once.

An example of control by the above-described processing is shown in a timing chart of FIG. In the example of FIG. 15, the vehicle is left in the garage for a long time by turning on the block heater 70 while the engine 2 is stopped in a cold region,
This shows a state where the outside air temperature THE has become -30 ° C. The heat generated by the block heater 70 causes the cooling water temperature THW
Is maintained at 20 ° C., but the intake air temperature THA is −20 ° C.
In addition, the AT operating oil temperature ATH has dropped to -25 ° C.

At time t20, the block heater 70
Is disconnected from the outlet 72a of the AC power supply 72, and the power supply to the block heater 70 is stopped. Next, at time t21, the ignition key is turned to start cranking by the starter. At this time, the fuel injection amount Q is set based on the cooling water temperature THW (= 20 ° C.). As a result, the required fuel injection amount Q is injected from the fuel injection valves 24-38 at the cooling water temperature THW of 20 ° C.

Then, the engine speed NE increases,
At time t12, the start is completed by once exceeding the start completion reference rotational speed Ns. However, the cooling water temperature THW = 20 ° C.
In the required fuel injection amount Q, stable combustion does not occur in some of the cylinders due to the temperature difference between the cylinders, and immediately after this, the engine speed NE sharply decreases. Then, the engine speed NE is determined by the cylinder temperature difference occurrence flag Fh = “O
N ”, the rotation speed falls below the decrease determination rotation speed NEL set to be higher than usual before the determination standby time S elapses (time t23).

As a result, the value of the starting fuel injection amount storage value Qa used in steps S630 to S650 of the fuel injection amount control process (FIG. 10) is updated to a higher value.
For this reason, when the temperature difference between the cylinders is generated, the required amount of fuel injection Q is injected from the fuel injection valves 24 to 38, and the combustion chamber is brought into a mixture state required for stable combustion. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to execution of the idle speed feedback control and the air-fuel ratio feedback control.

Further, a post-start fuel injection timing setting process (FIG. 1)
According to 4), when the process of updating the start-time fuel injection amount storage value Qa in step S820 is performed, the intake synchronous injection is performed during the time D. Therefore, the fuel injection valve 2
The fuel injected toward intake ports 8a to 22a at 4 to 38 is immediately sucked into the combustion chamber together with the intake air. Therefore, the amount of fuel adhering to the intake ports 8a to 22a is reduced, and the fuel concentration in the combustion chamber can be increased.

It should be noted that, as in the prior art, the decrease determination rotational speed NE
When L remains low (shown in parentheses in FIG. 15), the cooling water temperature T
Even if the fuel injection amount Q is determined only by HW (= 20 ° C.), the engine speed NE does not fall below the decrease determination speed NEL immediately thereafter. Therefore, the starting fuel injection amount storage value Q
a is not updated and the intake asynchronous injection remains. For this reason, the fuel injection amount Q remains considerably smaller than the required amount as shown by the broken line, and the amount of adhesion is not reduced by the intake synchronous injection, so that stable rotation of the engine 2 cannot be obtained, and Is more likely to occur.

In the configuration of the second embodiment described above, steps S340 to S340 in the cylinder-to-cylinder temperature difference occurrence determination processing (FIG. 7) are performed.
360 is a process as the cylinder-to-cylinder temperature difference determination means, and a poor fuel increase process is an increase process when the engine speed is low (FIG. 11).
Steps S800 to S820 and steps S950, S970, and S950 in the post-start fuel injection timing setting process (FIG. 14).
S930 corresponds to a process as a leaning suppression unit.

According to the second embodiment described above, the following effects can be obtained. (I). If the inter-cylinder temperature difference is determined to be large in the inter-cylinder temperature difference occurrence determination process (FIG. 7) when the engine 2 is started by the poor fuel increase process (FIG. 11) (S740). "YES"), the start-up fuel injection amount storage value Qa is updated to a large value by increasing the decrease determination rotation speed NEL (S800) (S820), and the decrease in the fuel vapor concentration in the combustion chamber is suppressed. I have.

Thus, when the engine 2 is started,
Even when the set amount (S560) of the startup fuel injection amount storage value Qa is reduced because the cooling water temperature THW is relatively high due to the operation of the block heater 70, the startup fuel injection amount storage value thereafter Since Qa is updated to a large value (S820), it is possible to suppress the fuel concentration in the combustion chamber from decreasing.

As described above, when the temperature difference between the cylinders becomes large due to the operation of the block heater 70 when the engine 2 is started, the fuel vapor concentration in the combustion chamber is increased by the rough fuel increasing process. By suppressing the decrease in the fuel concentration, an appropriate fuel concentration can be obtained. When the temperature difference between the cylinders is not large, a normal rough fuel increase process is performed, and an appropriate fuel concentration can be obtained by not suppressing a decrease in the fuel vapor concentration in the combustion chamber.
Therefore, the engine start control can be appropriately performed.

(B). In the second embodiment, the leaning suppression means is realized as a part of the process by using the poor fuel increasing process (FIG. 11) and the post-start fuel injection timing setting process (FIG. 14).

As a result, the present invention can be easily realized without making a particularly large system change, so that the manufacturing cost can be reduced. (C). The same effect as (b) of the first embodiment is obtained.

[Third Embodiment] In a third embodiment, a fuel injection amount control process shown in FIG. 16 is executed instead of the fuel injection amount control process (FIG. 3) of the first embodiment, and in addition to this, Further, a post-start fuel injection timing setting process shown in FIG. 17 and a catalyst warm-up ignition retarding process shown in FIG. 19 are executed. The other configuration is the same as that of the first embodiment unless otherwise described.

The fuel injection amount control process (FIG. 16) will be described. In the fuel injection amount control process (FIG. 10),
Steps S1010, S1020, S1070-S11
70 denotes steps S110, S120, S170- in the fuel injection amount control process (FIG. 3) of the first embodiment.
This is the same as each process of S270. The third embodiment is different from the first embodiment in the processing after it is determined in step S1020 that it is the time of starting.

That is, when it is determined that the engine is at the time of starting ("YES" in S1020), the fuel injection amount at the time of starting is immediately obtained from the map shown in FIG. 4 of the first embodiment based on the cooling water temperature THW. Q is calculated (S10
60). Then, it is determined whether the inter-cylinder temperature difference occurrence flag Fh is "ON" (S1062).

Here, if Fh = “OFF” (S1
(NO in 062), the fuel injection amount Q obtained in step S1060 is set as the starting fuel injection amount storage value Qa (S1070), and the fuel injection amount Q is further set to the fuel injection valve 24.
The time is set as the valve opening time of ３８38 (S1080), and the present process is ended once.

On the other hand, if Fh = “ON” (“YES” in S1062), the fuel injection amount Q obtained in step S1060 is increased by the reference increase value α as shown in the following equation 3. Is performed (S1064).

[0134]

Q ← Q + α (Equation 3) The increased fuel injection amount Q is set as a starting fuel injection amount storage value Qa (S1070), and the fuel injection amount Q is further set to the fuel injection valve. The time is set as the valve opening time of 24-38 (S1080), and this process is once ended.

Therefore, the fuel injection amount control process (FIG. 1)
In 6), if the inter-cylinder temperature difference occurrence flag Fh is “ON”, the fuel injection amount Q obtained based on the cooling water temperature THW is directly increased.

Next, a post-start fuel injection timing setting process (FIG. 1)
7) will be described. This process is a process that is repeatedly executed in a fixed time cycle. When the process is started, first, it is determined whether or not the engine is at the start (S1210). If it is the start time ("YES" in S1210), "OFF" is set to the post-start fuel injection timing setting completion flag Fz (S1).
220). Then, it is determined whether the time C has elapsed (S1230). This time C represents a continuation reference time of the intake synchronous injection setting (S1240) performed at the time of starting. At first, since the fuel injection itself has not been executed yet, the time C has not elapsed (“N” in S1230).
O "), and then intake synchronous injection is set (S124).
0). Here, the intake synchronous injection is as described in the second embodiment. Thus, the present process is temporarily terminated.

As a result, fuel is injected from the fuel injection valves 24-38 in the intake stroke, so that the injected fuel is immediately sucked into the combustion chamber together with the intake air. Then, at the time of starting, the setting of the intake synchronous injection (S1240) continues until the time C elapses ("NO" in S1230). Then, when the time C has elapsed (“Y” in S1230)
ES "), and intake asynchronous injection is set (S126).
0). Asynchronous intake injection is as described in the second embodiment.

Thus, the present processing is once ended. As a result, fuel is injected from the fuel injection valves 24-38 before the intake stroke, so that the intake ports 8a-22
The fuel that has become the vapor after adhering to a is sucked into the combustion chamber together with the intake air in the intake stroke.

Then, when the start is completed ("NO" in S1210), the inter-cylinder temperature difference occurrence flag Fh set in the inter-cylinder temperature difference occurrence determination processing (Embodiment 1: FIG. 7) is then turned on. It is determined whether it is “ON” (S125)
0). Fh = “OFF” (“N” in S1250)
O ”), that is, when the temperature difference between the cylinders is not a problem, the intake asynchronous injection is set (S126).
0) This process is temporarily terminated.

On the other hand, when Fh = “ON” (S1250)
If the temperature difference between the cylinders becomes a problem, the post-start fuel injection timing setting completion flag Fz
Is determined to be “OFF” (S1270).

If Fz = "ON"("NO" in S1270), intake asynchronous injection is set (S126).
0), this process is temporarily terminated, but initially, Fz = “OF
F ”(“ YES ”in S1270), the average value Tab of the cooling water temperature THW and the intake air temperature THA is calculated by the following equation (4).
(S1280).

[0142]

[Expression 4] Tab ← (THW + THA) / 2 [Equation 4] Then, based on the average value Tab, a time E is calculated from a map showing a tendency in FIG. 18 (S1290). This time E represents the continuation reference time of the intake synchronous injection setting (S1240) which is executed after “YES” is determined in step S1250.

Next, it is determined whether or not the time E has elapsed (S1300). If the time E has not elapsed ("NO" in S1300), the setting of intake synchronous injection is performed (S1240). Thus, the present process is temporarily terminated. As a result, fuel is injected from the fuel injection valves 24 to 38 in the intake stroke.

When the time E has elapsed (“YE” in S1300)
S)), then, “ON” is set to the post-start fuel injection timing setting completion flag Fz (S1310), intake asynchronous injection is set (S1260), and the present process is ended once.

The catalyst warm-up ignition retarding process (FIG. 19) will be described. This process is a process that is repeatedly executed in a fixed time cycle. When this process is started, first, the catalyst temperature T
The calculation of cat is performed (S1410). This calculation is
The operating temperature of the engine 2, for example, the ignition timing, the engine speed NE, the intake pressure PM, the elapsed time from the start or the total exhaust amount from the start, etc. Is estimated. Instead of this, the catalytic converter 68
May be arranged to directly detect the catalyst temperature Tcat.

Next, it is determined whether or not the catalyst temperature Tcat is equal to or higher than the catalyst activation reference temperature Tt (S
1420). If Tcat ≧ Tt (“YES” in S1420), the present process is temporarily ended as it is.

If Tcat <Tt ("NO" in S1420), then the cylinder-to-cylinder temperature difference occurrence flag Fh is set to "OF".
F "is determined (S1430). Fh = “OF
If it is “F” (“YES” in S1430), the ignition timing retarding process for catalyst warm-up is executed (S1440) because the cylinder-to-cylinder temperature difference is of a degree that does not cause a problem. As a result, the temperature of the exhaust gas from the combustion chamber becomes high, and the catalyst in the catalytic converter 68 is activated early. Thus,
This process is temporarily ended.

On the other hand, if Fh = “ON” (S143)
0 and “NO”), since the temperature difference between the cylinders is of a problematic degree and the flammability is reduced, the ignition timing retarding process should be executed to prevent further deterioration of combustion. Instead, the process is temporarily terminated.

In the configuration of the third embodiment described above, steps S340 to S340 in the cylinder-to-cylinder temperature difference occurrence determination processing (FIG. 7) are performed.
Step 360 is the processing as the cylinder-to-cylinder temperature difference determination means, and steps S1062 and S10 of the fuel injection amount control processing (FIG. 16).
64 and steps S1250, S1280 to S1300, S124 of the post-start fuel injection timing setting process (FIG. 17).
0 corresponds to the processing as the leaning suppression means.

According to the third embodiment described above, the following effects can be obtained. (I). In the fuel injection amount control process (FIG. 16), when the engine 2 is started, it is determined that the inter-cylinder temperature difference is large in the inter-cylinder temperature difference occurrence determination process (FIG. 7) ("S1062"). YES "), the fuel injection amount Q obtained by the cooling water temperature THW is increased and corrected (S106).
4). Thus, a decrease in the fuel vapor concentration in the combustion chamber can be suppressed.

As described above, when the temperature difference between the cylinders becomes large due to the operation of the block heater 70 when the engine 2 is started, the combustion is performed by directly increasing the fuel injection amount Q. This suppresses the decrease in the fuel vapor concentration in the room. As a result, an appropriate fuel concentration can be obtained. When the temperature difference between the cylinders is not large, an appropriate fuel concentration can be obtained by setting the normal fuel injection amount Q. Therefore, the engine start control can be appropriately performed.

(B). Further, in the post-start fuel injection timing setting process (FIG. 17), after the start of the engine 2, it is determined in the inter-cylinder temperature difference occurrence determination process (FIG. 7) that the inter-cylinder temperature difference is large ( In S1250, "YE
S "), an average value T of the cooling water temperature THW and the intake air temperature THA.
During the time E obtained by ab, the intake synchronous injection is executed (S1240). As a result, a decrease in the fuel vapor concentration in the combustion chamber can be more effectively suppressed. Therefore, the engine start control can be performed more appropriately.

(C). When the temperature difference between the cylinders becomes large, the fuel injection amount Q and the intake synchronous injection are directly increased in the fuel injection amount control process. Therefore, it is possible to suppress a decrease in the fuel vapor concentration due to an increase in the amount of fuel with a simple configuration.

Accordingly, the present invention can be easily realized without making a particularly large system change, so that the manufacturing cost can be suppressed. (D). In the third embodiment, if the temperature difference between the cylinders increases, the ignition timing retarding process for warming up the catalyst is not executed. As a result, the deterioration of the flammability due to the state where the temperature difference between the cylinders is large and the state where the ignition timing is retarded is not combined, and the rotation stability can be maintained and the deterioration of the emission can be prevented.

(E). The effect (b) of the first embodiment is obtained. [Other Embodiments] The first embodiment may further include a post-start fuel injection timing setting process (FIG. 14). Thus, it is possible to further suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber.

The first and second embodiments may be configured to further include a catalyst warm-up ignition retarding process (FIG. 19). As a result, compound deterioration in combustibility can be prevented, so that rotation stability can be maintained and emission deterioration can be prevented.

The first and third embodiments may be configured to further include a rough fuel increasing process (FIG. 11).
Thus, a decrease in the fuel vapor concentration in the combustion chamber can be further suppressed.

In the second and third embodiments, the intake synchronous injection is performed only for the time C at the time of starting, but this processing is not essential. That is, during this period, the intake asynchronous injection may be performed.

In each of the above embodiments, the state in which the temperature difference between the cylinders becomes large due to the operation of the block heater 70 is defined as the cooling water temperature THW and the outside air temperature TW.
The determination was made based on the state of the HE and the AT operating oil temperature ATH (FIG. 7: S340 to S360). In addition, only in the state of the cooling water temperature THW and the outside air temperature THE (S340, S
350). Also, the AT operating oil temperature ATH
Alternatively, the oil temperature of the engine oil, which is the lubricating oil, may be used. Further, the intake air temperature THA may be used instead of the outside air temperature THE. Further, a fuel temperature may be used instead of the AT working oil temperature ATH or the oil temperature of the engine oil.

In the fuel injection amount control process of the first embodiment (FIG. 3), the cylinder-to-cylinder temperature difference occurrence flag Fh = “ON”
In step S150 executed in the case of
The average value of HW and the intake air temperature THA is obtained, and the fuel injection amount Q
Was used for the calculation of In addition, when the inter-cylinder temperature difference occurrence flag Fh = “ON”, the average value of the cooling water temperature THW and the outside air temperature THE, the cooling water temperature THW and the AT operating oil temperature A
TH, the average value of the cooling water temperature THW and the oil temperature of the engine oil, the average value of the cooling water temperature THW and the fuel temperature,
Alternatively, an average value of two or more of the cooling water temperature THW and the outside air temperature THE, the AT operating oil temperature ATH, the oil temperature of the engine oil, and the fuel temperature, and further, an average value of all the temperatures including the cooling water temperature THW, and the like. May be calculated to calculate the fuel injection amount Q. In short, the fuel injection amount Q may be calculated using a value obtained by appropriately reducing the cooling water temperature THW.

In each of the above embodiments, the block heater 70 and the cooling water temperature sensor 82 are the same cylinder 8
, But may be arranged near a different cylinder. However, when the block heater 70 and the cooling water temperature sensor 82 are arranged near the same cylinder 8, the state in which the temperature difference between the cylinders due to the energization of the block heater 70 increases is more accurately detected. can do.

In each of the above embodiments, the intake pressure sensor 7
6, the amount of intake air may be detected by using various air flow meters instead. In this case, the map for obtaining the basic fuel injection amount QBS shown in FIG. 5 uses the engine speed NE and the intake air amount as parameters.

Although the embodiments of the present invention have been described above, the embodiments of the present invention include the following various technical items in addition to the technical items described in the claims. It should be noted that it has.

(1). In addition to the configuration according to any one of claims 1 to 13, when the temperature difference between the cylinders is determined to be large by the temperature difference between cylinders at the time of starting the internal combustion engine, the exhaust gas purification is performed. An internal combustion engine control device comprising: ignition retard prohibition means for prohibiting execution of an ignition timing delay process for warming up a catalyst.

When it is determined that the cylinder-to-cylinder temperature difference is large, the ignition retard inhibition means inhibits the execution of the ignition timing delay processing for warming up the exhaust gas purification catalyst. The deterioration of the flammability due to the large temperature difference between the cylinders and the ignition timing retardation does not combine. For this reason, rotation stability can be maintained and emission deterioration can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an engine according to a first embodiment.

FIG. 2 is a block diagram illustrating a schematic configuration of an engine control system according to the first embodiment.

FIG. 3 is a flowchart of a fuel injection amount control process according to the first embodiment.

FIG. 4 is a diagram illustrating a map configuration for obtaining a fuel injection amount Q based on a temperature variable T in the first embodiment.

FIG. 5 is a diagram illustrating a map configuration for obtaining a basic fuel injection amount QBS based on an intake pressure PM and an engine speed NE in the first embodiment.

FIG. 6 is a diagram illustrating a map configuration for obtaining a fuel injection amount cold correction coefficient Kq from a cooling water temperature THW in the first embodiment.

FIG. 7 is a flowchart of an inter-cylinder temperature difference occurrence determination process according to the first embodiment;

FIG. 8 is a timing chart showing an example of control according to the first embodiment.

FIG. 9 is a timing chart illustrating an example of control according to the first embodiment;

FIG. 10 is a flowchart of a fuel injection amount control process according to the second embodiment.

FIG. 11 is a flowchart of a poor fuel increasing process according to the second embodiment.

FIG. 12 is an explanatory diagram of a map configuration for obtaining a decrease determination rotation speed NEL from a cooling water temperature THW in the second embodiment.

FIG. 13 is an explanatory diagram of a map configuration for obtaining a starting fuel injection amount storage value Qa from a cooling water temperature THW in the second embodiment.

FIG. 14 is a flowchart of a post-start fuel injection timing setting process according to the second embodiment.

FIG. 15 is a timing chart showing an example of control according to the second embodiment.

FIG. 16 is a flowchart of a fuel injection amount control process according to the third embodiment.

FIG. 17 is a flowchart of a post-start fuel injection timing setting process according to the third embodiment.

FIG. 18 is an explanatory diagram of a map configuration for obtaining a time E from an average value Tab of the cooling water temperature THW and the intake air temperature THA in the third embodiment.

FIG. 19 is a flowchart of a catalyst warm-up ignition retarding process according to the third embodiment.

[Explanation of symbols]

2 ... Engine, 4,6 ... Bank, 8,10,12,1
4, 16, 18, 20, 22 ... cylinders, 8a to 10a, 1
2a, 14a, 16a, 18a, 20a, 22a ... intake ports, 8b, 10b, 12b, 14b, 16b, 18
b, 20b, 22b ... exhaust ports, 8c, 10c, 12
c, 14c, 16c, 18c, 20c, 22c: spark plugs, 8d, 10d, 12d, 14d, 16d, 18
d, 20d, 22d ... igniter, 24, 26, 28,
30, 32, 34, 36, 38 ... fuel injection valves, 40, 4
2, 44, 46, 48, 50, 52, 54 ... intake manifold, 56 ... surge tank, 58 ... intake path, 60 ...
Throttle valve, 60a ... Throttle valve drive motor, 62 ... Air cleaner, 64, 66 ... Exhaust manifold, 67 ... Exhaust pipe, 68 ... Catalytic converter, 70 ... Block heater, 70a ... Plug, 72 ... AC power supply, 72
a ... outlet, 74 ... intake air temperature sensor, 75 ... throttle opening sensor, 76 ... intake pressure sensor, 78 ... engine speed sensor, 80 ... cylinder discrimination sensor, 82 ... cooling water temperature sensor, 84 ... air-fuel ratio sensor, 90 ... ECU, 90a ...
Bidirectional bus, 90b CPU, 90c ROM, 90d
... RAM, 90e ... Backup RAM, 90f ... Input circuit, 90g ... Output circuit, 92 ... AT oil temperature sensor, 93
... Ambient temperature sensor, 94 ... Accelerator opening sensor, 96 ... Starter motor.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G084 BA13 CA01 CA02 DA09 DA12 EA11 EB08 EB11 FA02 FA06 FA10 FA11 FA20 FA38 FA39 3G301 HA01 HA08 JA00 JA33 KA02 KA05 LB02 MA12 MA13 MA22 NA08 NC02 ND01 NE01 NE08 PA06Z PA07Z PA02Z PE05Z PE08Z PF03Z PF07Z PF08Z

Claims (13)

[Claims] An internal combustion engine control device for use in a multi-cylinder internal combustion engine having a heater that suppresses a low temperature of the internal combustion engine by supplying thermal energy to cooling water of the internal combustion engine when the internal combustion engine is stopped. An inter-cylinder temperature difference judging unit for judging whether or not a temperature difference between the cylinders due to the operation of the heater is large when the engine is started; and a cooling water temperature detecting unit for detecting a temperature of a cooling water of the internal combustion engine When starting the internal combustion engine, when the cylinder-to-cylinder temperature difference determination means determines that the cylinder-to-cylinder temperature difference is large,
An internal combustion engine control device, comprising: engine control means for performing engine control according to a temperature lower than the cooling water temperature detected by the cooling water temperature detection means. 2. An internal combustion engine control device for use in a multi-cylinder internal combustion engine having a heater that suppresses a low temperature of the internal combustion engine by supplying thermal energy to cooling water of the internal combustion engine when the internal combustion engine is stopped. An inter-cylinder temperature difference determining means for determining whether a temperature difference between the cylinders due to the operation of the heater is large when the engine is started, and the inter-cylinder temperature difference determination when the internal combustion engine is started. If the means determines that the temperature difference between the cylinders is large,
An internal combustion engine control device, comprising: a leaning suppression unit that suppresses a decrease in fuel vapor concentration in an intake pipe and a combustion chamber. 3. The internal combustion engine according to claim 1, wherein said inter-cylinder temperature difference judging means converts two or more detected values representing the temperature of the internal combustion engine or the ambient temperature of the internal combustion engine when the internal combustion engine is started. An internal combustion engine control device that determines whether or not the cylinder-to-cylinder temperature difference is large based on the determination. 4. The configuration according to claim 3, wherein the detected value is at least two of a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, an outside air temperature, an intake air temperature, and a hydraulic oil temperature of the transmission. An internal combustion engine control device characterized by the above-mentioned. 5. The internal combustion engine control device according to claim 3, wherein the detected values are a cooling water temperature of the internal combustion engine, an outside air temperature, and a hydraulic oil temperature of the transmission. 6. The internal combustion engine control device according to claim 3, wherein the detected values are a coolant temperature, an intake air temperature, and a hydraulic oil temperature of a transmission of the internal combustion engine. 7. The internal combustion engine control device according to claim 3, wherein the detected values are a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an outside air temperature. 8. The internal combustion engine control device according to claim 3, wherein the detected values are a coolant temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an intake air temperature. 9. The internal combustion engine control device according to claim 3, wherein said detected values are a cooling water temperature and an outside air temperature of the internal combustion engine. 10. The temperature control device according to claim 2, wherein the leaning suppression means reduces the detected cooling water temperature in a cold fuel increase process using the cooling water temperature of the internal combustion engine as a parameter. The internal combustion engine control device according to claim 1, wherein the fuel supply amount is increased to suppress a decrease in fuel vapor concentration in the intake pipe and the combustion chamber. 11. The engine control device according to claim 2, wherein said lean-inhibiting means includes an engine-speed-reduction increasing process executed immediately after the engine starts when the engine speed falls below the reference engine speed. An internal combustion engine control apparatus characterized in that a reduction in fuel vapor concentration in the intake pipe and in the combustion chamber is suppressed by increasing the probability of executing the increase processing when the engine speed decreases. 12. The fuel supply control device according to claim 2, wherein said lean-inhibition means directly executes a fuel increase process when said inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large. An internal combustion engine control device characterized in that a reduction in fuel vapor concentration in the intake pipe and the combustion chamber is suppressed by executing the following. 13. An internal combustion engine according to claim 2, wherein said internal combustion engine is an intake port fuel injection type internal combustion engine for injecting fuel into an intake port, and said leaning suppressing means is provided by said cylinder-to-cylinder temperature difference determining means. An internal combustion engine control apparatus characterized in that when it is determined that the inter-temperature difference is large, fuel is injected into an intake port during an intake stroke to suppress a decrease in fuel vapor concentration in a combustion chamber.