JP3744318B2 - Internal combustion engine control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal combustion engine control device used in a multi-cylinder internal combustion engine provided with a heater that suppresses a low temperature of an internal combustion engine by supplying thermal energy to cooling water of the internal combustion engine when the internal combustion engine is stopped.
[0002]
[Prior art]
At the time of cold start of the internal combustion engine, in order to maintain the rotational stability at the start or after the start, the fuel increase is executed according to, for example, the cooling water temperature or the intake air temperature (Japanese Patent Laid-Open No. 63-38638). . As a result, even if the evaporation of fuel adhering to a low-temperature intake port or the like is delayed, it is possible to prevent the fuel concentration of the air-fuel mixture sucked into the combustion chamber from diluting and to maintain the rotational stability at the start or after the start. be able to.
[0003]
Also, in cold regions, in order to prevent engine start failure due to extremely low temperatures of the internal combustion engine, heat energy is supplied to the cooling water of the internal combustion engine with a heater, a so-called block heater, when the internal combustion engine is stopped. Thus, it is possible to suppress the low temperature of the internal combustion engine.
[0004]
[Problems to be solved by the invention]
However, when the temperature of the internal combustion engine is suppressed using the block heater while the engine is stopped, the cylinder close to the block heater is maintained at a sufficient temperature even when the internal combustion engine is stopped. In the cylinder far from the block heater, the temperature may not be sufficiently maintained. Therefore, when trying to execute the above-described increase in cold fuel by capturing the coolant temperature, a relatively high coolant temperature is detected depending on the mounting position of the coolant temperature sensor. It may not be possible to execute.
[0005]
Thus, when starting the internal combustion engine, there is a problem that the engine control according to the detected value of the cooling water temperature sensor cannot be performed properly due to the operation of the block heater.
[0006]
An object of the present invention is to provide an internal combustion engine control device capable of executing appropriate engine start control when starting an internal combustion engine equipped with the above-described heater.
[0007]
[Means for Solving the Problems]
In the following, means for achieving the above object and its effects are described.
The internal combustion engine control apparatus according to claim 1 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 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 or not a temperature difference between the cylinders due to the operation of the heater is large when starting the internal combustion engine; and a temperature of cooling water of the internal combustion engine. When the cooling water temperature detecting means to detect and the inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large at the start of the internal combustion engine, the cooling water temperature detecting means detects the detected temperature. Engine control means for performing engine control according to a temperature lower than the cooling water temperature.
[0008]
When the internal combustion engine is started, the engine control means determines that the inter-cylinder temperature difference determination means determines that the inter-cylinder temperature difference is greater than the cooling water temperature detected by the cooling water temperature detection means. The engine is controlled according to the low temperature.
[0009]
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 according to the temperature lower than the cooling water temperature can be performed, and the temperature difference between the cylinders becomes large. If not, the engine control means can perform normal engine start control according to the coolant temperature.
[0010]
For this reason, it is possible to execute appropriate engine start control when starting the internal combustion engine provided with the heater.
The internal combustion engine control device 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 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 or not a temperature difference between cylinders due to the operation of the heater is large at the time of starting the internal combustion engine, and at the time of starting the internal combustion engine, And a dilution suppression means for suppressing a decrease in fuel vapor concentration in the intake pipe and in the combustion chamber when the temperature difference determination means determines that the temperature difference between the cylinders is large. And
[0011]
When the internal combustion engine is started, the dilution suppression means reduces the fuel vapor concentration in the intake pipe and the combustion chamber when the inter-cylinder temperature difference determination means determines that the inter-cylinder temperature difference is large. Suppress. As a result, when the internal combustion engine is started, even when the degree of increase in the fuel supply amount is lowered because the cooling water temperature is relatively high due to the operation of the heater, the dilution control means is provided in the intake pipe and the combustion chamber. In order to suppress a decrease in the fuel vapor concentration in the room, the fuel concentration in the intake pipe and the combustion chamber does not become too thin.
[0012]
As described above, when the temperature difference between the cylinders is large at the start of the internal combustion engine, an appropriate fuel concentration can be obtained by suppressing a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber. . In addition, when the temperature difference between the cylinders is not large, the dilution 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 appropriately. .
[0013]
For this reason, 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, there is provided the internal combustion engine control apparatus according to the first or second aspect, wherein the inter-cylinder temperature difference determining means indicates the temperature of the internal combustion engine or the atmospheric temperature of the internal combustion engine when the internal combustion engine is started. It is characterized in that it is determined whether or not the temperature difference between the cylinders is large based on the detected values of more than one type.
[0014]
Whether or not the temperature difference between cylinders is large when the internal combustion engine is started by the inter-cylinder temperature difference determination means is based on two or more kinds of detected values representing the temperature of the internal combustion engine or the atmospheric temperature of the internal combustion engine. It can be carried out.
[0015]
That is, for example, when the internal combustion engine is started, if a difference equal to or greater than a reference value occurs between these detected values, it can be determined that the temperature difference between the cylinders is large.
[0016]
This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater.
According to a fourth aspect of the present invention, there is provided the internal combustion engine control apparatus according to the third aspect, wherein the detected value is a value of an internal combustion engine cooling water temperature, an internal combustion engine lubricating oil temperature, an outside air temperature, an intake air temperature, or a transmission hydraulic oil temperature. It is characterized by two or more.
[0017]
Thus, by comparing these states using 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, or the hydraulic oil temperature of the transmission, the temperature difference between the cylinders can be reduced. It can be determined that it has increased.
[0018]
This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped 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.
[0019]
Thus, by comparing these states using the three detected values of the coolant temperature, the outside air temperature, and the hydraulic fluid temperature of the transmission, it is determined with higher certainty that the temperature difference between the cylinders has increased. can do.
[0020]
This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped with 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 fluid temperature of the transmission.
[0021]
By comparing these states using the three detected values of the coolant temperature, the intake air temperature, and the hydraulic fluid temperature of the transmission in this way, it is determined with greater certainty that the temperature difference between the cylinders has increased. can do.
[0022]
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 value is a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an outside air temperature.
[0023]
Thus, by comparing these states using the three detected values of the coolant temperature, the lubricating oil temperature of the internal combustion engine, and the outside air temperature, it is possible to further increase the certainty that the temperature difference between the cylinders is large. Can be determined.
[0024]
This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater.
According to an eighth aspect of the present invention, in the configuration of the third aspect, the detected value is a cooling water temperature of the internal combustion engine, a lubricating oil temperature of the internal combustion engine, and an intake air temperature.
[0025]
Thus, by comparing these states using the three detected values of the coolant temperature, the lubricating oil temperature of the internal combustion engine, and the intake air temperature, it is possible to further increase the certainty that the temperature difference between the cylinders is large. Can be determined.
[0026]
This makes it possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater.
According to a ninth aspect of the present invention, in the configuration of the third aspect, the detected value is a cooling water temperature and an outside air temperature of the internal combustion engine.
[0027]
Thus, by comparing these states using the two detection values of the cooling water temperature and the outside air temperature, it can be determined that the temperature difference between the cylinders is large.
[0028]
Thus, even with a simple configuration, it is possible to execute appropriate engine start control when starting the internal combustion engine provided with the heater.
The internal combustion engine control apparatus according to claim 10 is the configuration according to claim 2, wherein the dilution control means detects the detected cooling with respect to the fuel increase process during cold using the cooling water temperature of the internal combustion engine as a parameter. By using a temperature in which the water temperature is corrected to decrease, the fuel supply amount is increased to suppress a decrease in fuel vapor concentration in the intake pipe and the combustion chamber.
[0029]
As a technique for suppressing a decrease in fuel vapor concentration in the intake pipe and in the combustion chamber, the dilution suppression means corrects the actual cooling water temperature for a cold fuel increase process using the cooling water temperature of the internal combustion engine as a parameter. Use temperature. As a result, the fuel supply amount is increased, and the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed.
[0030]
Therefore, by using the cold fuel increase processing 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 it is appropriate when starting an internal combustion engine equipped with a heater. It is possible to execute the engine start control.
[0031]
The internal combustion engine control apparatus according to claim 11 is the configuration according to claim 2, wherein the dilution control means increases the engine speed when the engine speed is reduced immediately after starting when the engine speed falls below a reference speed. In the above, the lowering of the fuel vapor concentration in the intake pipe and in the combustion chamber is suppressed by increasing the reference rotational speed to increase the probability of executing the increasing process when the engine rotational speed decreases.
[0032]
As a technique for suppressing a decrease in the fuel vapor concentration in the intake pipe and in the combustion chamber, the dilution suppression means is a reference in an increase process at the time of engine speed decrease that is executed when the engine speed falls below the reference speed immediately after starting. The engine speed is increased to increase the probability of executing the increase process when the engine speed is decreasing. As a result, the fuel supply amount is increased, and the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed.
[0033]
Therefore, by using the engine speed reduction 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 at the time of starting the internal combustion engine equipped with a heater. Appropriate engine start control can be executed.
[0034]
An internal combustion engine control apparatus according to a twelfth aspect of the present invention is the internal combustion engine control apparatus according to the second aspect, wherein the dilution control means determines that the inter-cylinder temperature difference is large by the inter-cylinder temperature difference determination means. In addition, the present invention is characterized in that a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber is suppressed by directly executing the fuel increase process.
[0035]
As a technique for suppressing the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber, the dilution suppression means may be configured to suppress the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber by directly executing the fuel increase process. good. This also makes it possible to suppress a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber with a simple configuration, and to perform appropriate engine start control when starting the internal combustion engine equipped with the heater.
[0036]
An internal combustion engine control apparatus according to claim 13 is the intake port fuel injection type internal combustion engine in which the internal combustion engine injects fuel into the intake port in the configuration according to claim 2, and the dilution suppression means includes the inter-cylinder temperature. When the difference determination means determines that the temperature difference between the cylinders is large, the fuel vapor concentration in the combustion chamber is suppressed from being lowered by injecting fuel into the intake port during the intake stroke. .
[0037]
When the internal combustion engine is an intake port fuel injection type internal combustion engine that injects fuel into the intake port, the diluting suppression means applies the intake port to the intake port during the intake stroke as a method for suppressing a decrease in fuel vapor concentration in the combustion chamber. You may make it inject a fuel. As a result, the fuel injected into the intake port immediately enters the combustion chamber together with the intake air, and the amount adhering to the intake port is reduced, so that a decrease in the fuel vapor concentration in the combustion chamber can be suppressed.
[0038]
As a result, it is possible to easily suppress a decrease in the fuel vapor concentration in the combustion chamber without relying on an increase in fuel, and it is possible to execute appropriate engine start control when starting the internal combustion engine equipped with the heater.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
[Embodiment 1]
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 8-cylinder engine mounted on a vehicle for automobiles, and includes two banks 4 and 6 each having four cylinders.
[0040]
Fuel is supplied to each of the cylinders 8, 10, 12, 14, 16, 18, 20, and 22 provided in the banks 4 and 6 toward the intake ports 8a, 10a, 12a, 14a, 16a, 18a, 20a, and 22a. Fuel injection valves 24, 26, 28, 30, 32, 34, 36, and 38 for injection are provided. Further, intake manifolds 40, 42, 44, 46, 48, 50, 52, 54 are connected to the intake ports 8a-22a of the respective cylinders 8-22, and the intake air from the surge tank 56 is supplied to the respective cylinders 8-22. is doing. The amount of intake air flowing into the surge tank 56 is adjusted by the opening of the throttle valve 60 (throttle opening TA) provided in the intake passage 58 upstream of the surge tank 56, and the intake air provided in each cylinder 8-22. When a valve (not shown) is opened, the cylinder is sucked into the cylinder in the intake stroke. The intake path 58 introduces outside air via the air cleaner 62.
[0041]
Exhaust manifolds 64 and 66 are connected to the exhaust ports 8b, 10b, 12b, 14b, 16b, 18b, 20b, and 22b of each cylinder 8-22. In the exhaust manifolds 64 and 66, exhaust valves (not shown) are opened during the exhaust stroke, and exhaust is discharged from the cylinders 8 to 22. The exhaust gas is purified by the catalyst in the catalytic converter 68 provided in the exhaust pipe 67 where the exhaust manifolds 64 and 66 join, and further discharged to the outside through a muffler (not shown).
[0042]
Spark plugs 8c, 10c, 12c, 14c, 16c, 18c, 20c, and 22c are provided in each cylinder 8-22. The spark plugs 8c to 22c cause spark discharge when the igniters 8d, 10d, 12d, 14d, 16d, 18d, 20d, and 22d generate high voltage at the ignition timing, and ignite and burn the mixture in the combustion chamber. Yes.
[0043]
A block heater 70 for heating internal cooling water when the engine 2 is stopped is attached to the cylinder block on one bank 4 side. The block heater 70 is provided to prevent the temperature of the engine 2 from being lowered when the vehicle is left in a garage or the like for a long time with the engine 2 stopped in a cold region. An electric heating wire is provided inside the block heater 70, and heat is generated by using electric power from a general household AC power source 72 by inserting the plug 70a into the outlet 72a. Then, the plug 70a is removed from the outlet 72a when the vehicle is traveling.
[0044]
In the first embodiment, the block heater 70 is disposed 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.
[0045]
An intake air temperature sensor 74 is provided in the intake passage 58 to detect the temperature of 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 to detect the intake pressure PM in the surge tank 56.
[0046]
Further, the opening degree TA of the throttle valve 60 provided in the intake passage 58 is detected by a throttle opening degree sensor 75.
In the vicinity of the crankshaft (not shown), an engine speed sensor 78 is provided that generates an output pulse every time the crankshaft rotates 10 °. Further, a cylinder discrimination sensor (also referred to as a cam angle sensor) 80 is provided that generates an output pulse when a specific cylinder reaches the intake top dead center from the rotation of the intake camshaft (not shown).
[0047]
Further, a coolant temperature sensor 82 for detecting the coolant temperature THW is provided in the vicinity of 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 component.
[0048]
The signals of the intake air temperature sensor 74, throttle opening sensor 75, intake air pressure sensor 76, engine speed sensor 78, cylinder discrimination sensor 80, cooling water temperature sensor 82 and air-fuel ratio sensor 84 are shown in the control system block diagram of FIG. Processing is performed by an electronic control unit (hereinafter referred to as “ECU”) 90.
[0049]
The ECU 90 includes a digital computer and includes a CPU 90b, a ROM 90c, a RAM 90d, a backup RAM 90e, an input circuit 90f, and an output circuit 90g that are connected to each other via a bidirectional bus 90a.
[0050]
Signals from the sensors 74 to 84 described above are taken into the ECU 90 and processed through the input circuit 90f. 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 pulses of the engine speed sensor 78.
[0051]
In addition to this, the vehicle includes an AT oil temperature sensor 92 that detects the temperature of hydraulic oil (AT hydraulic oil temperature ATH) of an automatic transmission (not shown), and an external temperature THE that is an ambient temperature around the engine 2. An air temperature sensor 93, an accelerator opening sensor 94 for detecting the amount of depression of an accelerator pedal (not shown) (hereinafter referred to as “accelerator opening”) ACCP, and other sensors are provided to control the operating state and atmosphere state of the engine 2. Detected.
[0052]
The ECU 90 also includes a motor 60a (DC motor or step motor) for driving the fuel injection valves 24 to 38 and the throttle valve 60, an igniter 8d to 22d, a starter motor 96, and other actuators, and an output circuit 90g. Is driving through.
[0053]
Thus, during the air-fuel ratio feedback control, the ECU 90 adjusts the fuel injection amount injected from the fuel injection valves 24 to 38 so as to reach the target air-fuel ratio according to the output of the air-fuel ratio sensor 84. In addition, for example, when it is necessary to increase the fuel concentration according to the operating state of the engine 2 such as during cold or high load, the fuel concentration is set higher than the target air-fuel ratio to improve the combustibility. In the catalytic converter 68, melting damage due to the high temperature of the catalyst is prevented.
[0054]
Further, the ECU 90 adjusts the opening degree of the throttle valve 60 via the throttle valve driving motor 60a in accordance with the accelerator opening degree ACCP detected by the accelerator opening degree sensor 94. At this time, feedback control is performed so that the throttle opening degree TA detected by the throttle opening degree sensor 75 becomes a target opening degree corresponding to the accelerator opening degree ACCP.
[0055]
Next, a fuel injection amount control process performed by the ECU 90 from the start to the start of the engine 2 will be described based on the flowchart of FIG. This process is a process started when the ignition switch is turned on, and is periodically executed for each preset crank angle. In addition, each process step in each flowchart demonstrated below is represented by "S-".
[0056]
When this fuel injection amount control process is started, first, engine operation such as engine speed NE, intake pressure PM, cooling water temperature THW, intake air temperature THA, AT hydraulic oil temperature ATH, outside air temperature THE, air-fuel ratio A / F, etc. The state is read into the work area of the RAM 90d (S110).
[0057]
Next, it is determined whether or not it is a start time (S120). Whether or not the engine is started is determined to be a start if the engine speed NE of the engine 2 that has started driving by cranking has not increased to the start completion reference engine speed Ns ("YES" in S120). It is determined whether the inter-cylinder temperature difference occurrence flag Fh obtained in the inter-cylinder temperature difference occurrence determination process is “ON” (S130).
[0058]
If Fh = “OFF” (“NO” in S130), the current coolant temperature THW is set in the temperature variable T (S140).
On the other hand, if Fh = “ON” (“YES” in S130), the temperature variable T is set to an average value of the current cooling water temperature THW and the intake air temperature THA as shown in the following equation 1, for example (S150). ).
[0059]
[Expression 1]
T ← (THW + THA) / 2 [Formula 1]
After step S140 or step S150, the fuel injection amount Q at the time of starting is calculated from the map showing the tendency in FIG. 4 based on the temperature variable T (S160).
[0060]
For example, when Fh = “OFF”, if the current cooling water temperature THW is Tx, T = Tx in step S140, and therefore, the value of the fuel injection amount Q = Qx is set as shown in FIG. However, when Fh = “ON”, if the current coolant temperature THW is Tx and the intake air temperature THA is Ty, as shown in FIG. 4, T = (Tx + Ty) / 2 (= Tm). Therefore, a value of fuel injection amount Q = Qm that is larger than Qx by ΔQ is set.
[0061]
Next, 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 this process is temporarily terminated.
[0062]
On the other hand, if it is not at the time of starting (“NO” in S120), it is next determined whether or not the starting is completed (S190). If it is before cranking (“NO” in S190), this process is temporarily terminated as it is.
[0063]
If the engine 2 starts to be 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). Next, the engine speed NE Based on the intake pressure PM, the basic fuel injection amount QBS is calculated from the map shown in FIG. 5 (S200). The basic fuel injection amount QBS indicates the fuel injection amount for the air-fuel mixture to become the stoichiometric air-fuel ratio under the conditions of the engine speed NE and the intake pressure PM.
[0064]
Next, based on the current coolant temperature THW, a fuel injection amount cold correction coefficient Kq is calculated from a map showing a tendency in FIG. 6 (S210). The fuel injection amount cold correction coefficient Kq (Kq> 0) is a coefficient for increasing the fuel injection amount required during cold.
[0065]
Next, as shown in the following equation 2, the post-startup fuel injection amount Qb is calculated (S220).
[0066]
[Expression 2]
Qb ← QBS · (1.0 + Kq + FAF + KG) + Kz [Formula 2]
Here, FAF represents an air-fuel ratio feedback coefficient for controlling the air-fuel ratio to a target air-fuel ratio (here, the stoichiometric air-fuel ratio), KG represents its learning value, and Kz represents another correction value. Note that, when the air-fuel ratio feedback control is not started immediately after the start or the like, FAF = “0”.
[0067]
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). If Qa> Qb immediately after the completion of the start (“YES” in S230), the start time fuel injection amount storage value Qa is slightly reduced by the gradual decrease process fd (Qa) (S240). Then, the starting fuel injection amount memory value Qa after the gradual decrease is set to the fuel injection amount Q (S250), the fuel injection amount Q is set as the valve opening time of the fuel injection valves 24-38 (S180), and once. This process ends.
[0068]
As long as Qa> Qb (“YES” in S230), the fuel injection amount Q that is gradually decreased is set to the fuel injection amount Q (S250), so that the fuel injection amount Q gradually increases. Get smaller.
[0069]
If Qa ≦ Qb is satisfied (“NO” in S230), the starting fuel injection amount storage value Qa is cleared (S260), and then the post-starting fuel injection amount Qb is set to the fuel injection amount Q (S270). ). Then, the fuel injection amount Q for which the post-startup fuel injection amount Qb is set is set as the valve opening time of the fuel injection valves 24 to 38 (S180), and this processing is temporarily ended.
[0070]
Thus, thereafter, the fuel injection amount Q based on the post-startup fuel injection amount Qb is set as the valve opening time of the fuel injection valves 24-38.
Next, the 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 process is repeatedly executed at regular time intervals.
[0071]
When this process is started, it is first determined whether or not the engine is starting (S310). The contents of this determination are the same as the processing in step S120 of the fuel injection amount control (FIG. 3).
If it is not at the time of starting (“NO” in S310), next, “OFF (incomplete)” is set to the determination completion flag Fb indicating whether or not the determination of occurrence of temperature difference between the cylinders is completed (S320). This process is temporarily terminated.
[0072]
If it is at the time of starting (“YES” in S310), it is determined whether or not the determination completion flag Fb is “OFF” (S330). If Fb = “ON (completed)” (“NO” in S330), the process is temporarily terminated as it is, but initially Fb = “OFF” (“YES” in S330), and then the current It is determined whether or not the cooling water temperature THW is higher than 10 ° C. (S340).
[0073]
If THW> 10 ° C. (“YES” in S340), it is next determined whether or not the outside air temperature THE is lower than −20 ° C. (S350). If THE <−20 ° C. (“YES” in S350), it is then determined whether or not the AT hydraulic oil temperature ATH is lower than −20 ° C. (S360). If ATH <−20 ° C. (“YES” in S360), “ON” is set to the inter-cylinder temperature difference occurrence flag Fh (S370). As described above, when both the outside air temperature THE and the AT hydraulic oil temperature ATH are low temperatures below −20 ° C. even though the cooling water temperature THW is at a certain high temperature, the block is kept until immediately before starting. It is determined that the heater 70 was operating. That is, the operation of the block heater 70 causes a temperature difference between the cylinders 8 to 22 of the engine 2 to cause a problem if the engine 2 is controlled with the detected value of the cooling water temperature sensor 82 as it is. Show.
[0074]
On the other hand, when the coolant temperature THW is 10 ° C. or lower (“NO” in S340), the outside air temperature THE is −20 ° C. or higher (“NO” in S350), the AT hydraulic oil temperature ATH is −20 ° C. or higher. If there is one (“NO” in S360), “OFF” is set to the inter-cylinder temperature difference occurrence flag Fh (S380). That is, even if the block heater 70 is not operated, or even if the block heater 70 is operated, there is a temperature difference between the cylinders 8 to 22 of the engine 2 that causes a problem even if the coolant temperature THW is used for control as it is. It has not occurred.
[0075]
Then, when the process of step S370 or step S380 is completed, “ON” is set to the determination completion flag Fb (S385), and this process is temporarily terminated.
In this way, the determinations of steps S340 to S360 are made only once at the time of starting, and either “ON” or “OFF” is set in the inter-cylinder temperature difference generation flag Fh.
[0076]
Based on the inter-cylinder temperature difference occurrence flag Fh set in this way, the cooling water temperature THW is used for control as it is at the start in the fuel injection amount control process (FIG. 3) (S140), or the cooling water temperature THW and the intake air temperature It is determined whether the average value with THA is used (S150) (S130).
[0077]
An example of control by the above-described processing is indicated by a solid line in the timing charts of FIGS.
The example of FIG. 8 shows a state where the vehicle is left in the garage for a long time by energizing (ON) the block heater 70 with the engine 2 stopped in a cold region, and the outside temperature THE becomes −30 ° C. ing. While the engine 2 is stopped, the cooling water temperature THW is maintained at 20 ° C. due to the heat generated by the block heater 70, but the intake air temperature THA is reduced to −20 ° C. and the AT hydraulic oil temperature ATH is reduced to −25 ° C. ing.
[0078]
In order to start the engine 2, at time t0, the plug 70a of the block heater 70 is removed from the outlet 72a of the AC power source 72 (OFF), and energization to the block heater 70 is stopped. Next, at the time t1, the ignition key is turned to start cranking by the starter. At this time, since the inter-cylinder temperature difference generation flag Fh is set to “ON”, the fuel injection amount Q is an average value of the cooling water temperature THW (= 20 ° C.) and the intake air temperature THA (= −20 ° C.). It is set based on a certain 0 ° C. Thus, the fuel injection amount Q corresponding to THW = 0 ° C. is injected from the fuel injection valves 24 to 38, and the combustion chamber is in the air-fuel mixture state necessary for stable combustion.
[0079]
Therefore, the engine speed NE rises rapidly and exceeds the start completion reference speed Ns at time t2. This completes the start-up. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to the execution of idle speed feedback control and air-fuel ratio feedback control.
[0080]
When the fuel injection amount Q is determined only by the cooling water temperature THW (= 20 ° C.) as in the prior art, the fuel injection amount Q becomes considerably smaller than the amount necessary for stable combustion as shown by the broken line, and the engine 2 is difficult to start, or even if it is started, stable rotation cannot be obtained, and there is a high risk of engine stall.
[0081]
In the example of FIG. 9, in a cold region, the engine 2 is stopped, the block heater 70 is not energized (OFF) and left in the garage, the outside air temperature THE becomes −25 ° C., and the cooling water temperature THW is −10. In the graph, the intake air temperature THA is lowered to -15 ° C, and the AT hydraulic oil temperature ATH is lowered to -22 ° C.
[0082]
Under this situation, the ignition key is turned at time t11 to start cranking by the starter. At this time, since “OFF” is set in the inter-cylinder temperature difference occurrence flag Fh, the fuel injection amount Q is set based on the coolant temperature THW (= −10 ° C.). As a result, the fuel injection amount Q corresponding to the value of the coolant temperature THW (= −10 ° C.) itself is injected from the fuel injection valves 24 to 38, and the combustion chamber is in an air-fuel mixture state necessary for stable combustion. .
[0083]
Therefore, the engine speed NE rises rapidly, and the start is completed by exceeding the start completion reference speed Ns at time t12. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to the execution of idle speed feedback control and air-fuel ratio feedback control.
[0084]
In the configuration of the first embodiment described above, the cooling water temperature sensor 82 corresponds to the cooling water temperature detecting means. Steps S340 to 360 correspond to the processing as the cylinder temperature difference determination means, and steps S130 and S150 to S180 correspond to the processing as the engine control means.
[0085]
According to the first embodiment described above, the following effects can be obtained.
(I). In the fuel injection amount control process (FIG. 3), when the engine 2 is started, if it is determined in the inter-cylinder temperature difference occurrence determination process (FIG. 7) that the inter-cylinder temperature difference is large (in S130). “YES”), an averaging process (S150) of the coolant temperature THW and the intake air temperature THA is performed. Thus, fuel injection can be executed with the fuel injection amount Q corresponding to a temperature lower than the coolant temperature THW detected by the coolant temperature sensor 82.
[0086]
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 is not large, normal engine start control according to the coolant temperature THW itself can be performed.
[0087]
For this reason, it is possible to execute appropriate engine start control when starting the engine 2 provided with the block heater 70.
(B). In the first embodiment, in particular, the three detected values of the coolant temperature THW, the outside air temperature THE, and the hydraulic oil temperature ATH of the automatic transmission are used, and these states are compared as in steps S340 to S360. Detecting a large temperature difference.
[0088]
Although the outside air temperature THE and the AT hydraulic oil temperature ATH are lower than −20 ° C., the state where the cooling water temperature THW is THW> 10 ° C. is almost certainly a state caused by the action of the block heater 70. With this, it can be determined with high certainty that the temperature difference between the cylinders is large.
[0089]
(C). Further, when it is found that the temperature difference between the cylinders is large, an appropriate fuel injection amount Q is obtained by using an average value of the cooling water temperature THW and the intake air temperature THA using a normal cold fuel increase process. Can be obtained. With such a simple configuration, the effects (a) and (b) can be produced, and the manufacturing cost can be suppressed.
[0090]
[Embodiment 2]
In the 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, a poor fuel increase process shown in FIG. 11 and a post-startup fuel injection timing setting process shown in FIG. 14 are executed. Other configurations are the same as those in the first embodiment unless otherwise specified.
[0091]
The fuel injection amount control process (FIG. 10) will be described. In this fuel injection amount control process (FIG. 10), steps S510, S520, S570 to S670 are the processes of steps S110, S120, S170 to S270 in the fuel injection amount control process (FIG. 3) of the first embodiment. Is the same. In the second embodiment, the processing after it is determined at step S520 that the engine is at the start is different from that in the first embodiment.
[0092]
In other words, if it is determined that the engine is at the time of starting (“YES” in S520), the fuel injection amount Q at the time of starting is calculated from the map immediately having the tendency shown in FIG. 4 (Embodiment 1) based on the coolant temperature THW. (S560). Then, this fuel injection amount Q is set as the start-time fuel injection amount storage value Qa (S570), and further the fuel injection amount Q is set as the valve opening time of the fuel injection valves 24-38 (S580). Exit.
[0093]
Accordingly, in the fuel injection amount control process (FIG. 10), the process does not change depending on whether or not the inter-cylinder temperature difference generation flag Fh is “ON”. Instead, in the second embodiment, measures are taken when the inter-cylinder temperature difference generation flag Fh is “ON” by using the poor fuel increase process (FIG. 11).
[0094]
Next, the bad fuel increase process (FIG. 11) will be described. This process is a process that is repeatedly executed at regular time intervals. When this process is started, it is first determined whether or not the start is complete (S710). If it is before the start or at the start (“NO” in S710), “OFF” is set to the rough fuel increase process completion flag Fy (S720), and this process is temporarily ended.
[0095]
If the engine 2 starts to be started by cranking and the engine speed NE has increased to the start completion reference speed Ns, the engine has been started ("YES" in S710). It is determined whether or not Fy is “OFF” (S730). If Fy = “ON”, the process is temporarily terminated as it is. However, since Fy = “OFF” is initially set (S730), the inter-cylinder temperature difference occurrence determination process (Embodiment 1: FIG. 7) is performed. It is determined whether or not the inter-cylinder temperature difference occurrence flag Fh set in step S is “ON” (S740).
[0096]
Here, if Fh = “OFF” (“NO” in S740), in order to determine the use of inferior fuel from the degree of decrease in engine speed immediately after starting, a map A showing a trend with a solid line A in FIG. Then, a decrease determination rotational speed NEL is calculated based on the coolant temperature THW (S750). Next, it is determined whether or not the value of the engine speed NE at the time of lowering is lower than the decrease determination speed NEL (S760). If NE ≧ NEL at the time of descent (“NO” in S760), it is next determined whether or not the time from the completion of the start is before the determination waiting time S (seconds) has elapsed (S780). If it is before the determination standby time S has elapsed (“YES” in S780), this processing is temporarily terminated as it is.
[0097]
When NE ≧ NEL at the time of the descent is maintained (“NO” in S760) and the determination standby time S has elapsed (“NO” in S780), the drop in the engine speed NE is small, so the fuel injection valves 24-38 It can be determined that the fuel injected from is not poor fuel. Therefore, next, the rough fuel increase processing completion flag Fy is set to “ON” (S790), and this processing is temporarily ended. Thereafter, since Fy = “ON” (“NO” in S730), the substantial process of the poor fuel increase process ends.
[0098]
Before the determination waiting time S has elapsed (“YES” in S780), if NE <NEL at the time of descending (“YES” in S760), the degree of decrease in the engine speed NE is large, and therefore poor fuel is used. It can be judged. Therefore, next, the starting fuel injection amount storage value Qa is updated based on the coolant temperature THW based on the map a showing the trend by the solid line a in FIG. 13 (S770). As described above, in order to improve the combustibility of the poor fuel, that is, the fuel that does not easily volatilize, the calculation (S560, S570) is performed in the fuel injection amount control process (FIG. 10) and used for the gradual decrease process (S640). A process for updating the starting fuel injection amount stored value Qa to a value as large as necessary according to the coolant temperature THW is executed.
[0099]
In this way, by updating the starting fuel injection amount storage value Qa to a large value, particularly in the gradual decrease processing (S640) of the fuel injection amount control processing (FIG. 10), the starting fuel injection amount updated to a large value is obtained. The process of gradually reducing the fuel injection amount from the stored value Qa continues.
[0100]
In this way, when the starting fuel injection amount storage value Qa is updated (S770), next, the rough fuel increase processing completion flag Fy is set to “ON” (S790), and this processing is once ended. Thereafter, since Fy = “ON” (“NO” in S730), the substantial process of the poor fuel increase process ends.
[0101]
On the other hand, if Fh = “ON” (“YES” in S740), the block heater 70 is operating when the engine 2 is stopped, resulting in a temperature difference between the cylinders. For this reason, in order to execute the fuel injection amount increase using the decrease in the engine speed immediately after the start, a map for determining the decrease based on the coolant temperature THW is shown by a map B showing a trend 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 this map B is designed to be set to a higher rotational speed than in the case of the map A for determining the above-mentioned poor fuel.
[0102]
Next, it is determined whether or not the value of the engine speed NE at the time of lowering is lower than the decrease determination speed NEL (S810). If NE ≧ NEL at the time of descent (“NO” in S810), it is next determined whether or not the time from completion of the start is before the determination waiting time S (seconds) has elapsed (S780). If it is before the determination standby time S has elapsed (“YES” in S780), this processing is temporarily terminated as it is.
[0103]
While the state of NE ≧ NEL when descending (“NO” in S810) and the determination standby time S has elapsed (“NO” in S780), it can be determined that the temperature difference between the cylinders is not a problem in practice. . Therefore, next, the rough fuel increase processing completion flag Fy is set to “ON” (S790), and this processing is temporarily ended. Thereafter, since Fy = “ON” (“NO” in S730), the substantial processing for countering the temperature difference between the cylinders ends.
[0104]
Before the determination waiting time S elapses (“YES” in S780), if NE <NEL at the time of lowering (“YES” in S810), the engine speed NE is greatly reduced, so countermeasures for the temperature difference between the cylinders are necessary. It can be judged that. Therefore, next, the starting fuel injection amount storage value Qa is updated based on the coolant temperature THW with the map b showing the trend with the solid line b in FIG. 13 (S820). That is, in order to counter the temperature difference between cylinders, the fuel injection amount storage value Qa at the time of start is calculated (S560, S570) in the fuel injection amount control process (FIG. 10) and used for the gradual decrease process (S640). Is updated to a value as large as necessary according to the coolant temperature THW.
[0105]
As a result, particularly in the gradual reduction process (S640) of the fuel injection amount control process (FIG. 10), the process of gradually decreasing the fuel injection amount from the increased starting fuel injection amount stored value Qa is continued.
[0106]
After updating the starting fuel injection amount storage value Qa in this way, next, the poor fuel increase processing completion flag Fy is set to “ON” (S790), and this processing is once ended. Thereafter, since Fy = “ON” (“NO” in S730), the substantial processing for countering the temperature difference between the cylinders ends.
[0107]
Next, the post-startup fuel injection timing setting process (FIG. 14) will be described. This process is a process that is repeatedly executed at regular time intervals.
When this process is started, first, it is determined whether or not it is a start time (S910). If it is during cranking (“YES” in S910), “OFF” is set to the post-startup fuel injection timing setting completion flag Fz (S915).
[0108]
Next, it is determined whether or not the time C has elapsed (S920). This time C represents the continuation reference time of the intake synchronous injection setting (S930) performed at the start. Since the fuel injection itself has not yet been executed at the beginning, the time C has not elapsed (“NO” in S920), and then the intake synchronous injection is set (S930). Here, the intake synchronous injection represents a fuel injection form in which fuel is injected from the fuel injection valves 24 to 38 toward the intake ports 8a to 22a in the intake stroke.
[0109]
Thus, the present process is temporarily terminated. As a result, fuel is injected from the fuel injection valves 24 to 38 during the intake stroke, so that the injected fuel is immediately taken into the combustion chamber together with the intake air.
[0110]
At the time of start-up, the setting of intake synchronous injection (S930) continues until time C has elapsed ("NO" in S920). Then, when the time C has elapsed (“YES” in S920), intake asynchronous injection is set (S940). Here, the intake asynchronous injection represents 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. .
[0111]
Thus, the present process is temporarily terminated. As a result, since fuel is injected from the fuel injection valves 24 to 38 before the intake stroke, the fuel that has become vapor after adhering to the intake ports 8a to 22a once together with the intake air in the intake stroke. Inhaled.
[0112]
When the start is completed (“NO” in S910), it is then determined whether or not the start time fuel injection amount storage value Qa has been updated in step S770 or step S820 of the poor fuel increase process (FIG. 11). (S950). When the start time fuel injection amount storage value Qa is not updated in step S770 or step S820 (“NO” in S950), that is, in either step S760 or step S810 of the poor fuel increase processing (FIG. 11), If it is determined that NE ≧ NEL at the time of descending, intake asynchronous injection is set (S940), and this process is temporarily terminated.
[0113]
On the other hand, when the starting fuel injection amount storage value Qa is updated in step S770 or step S820 (“YES” in S950), that is, either the step S760 or the step S810 of the poor fuel increase process (FIG. 11). If it is determined that NE <NEL at the time of lowering, it is next determined whether or not the post-startup fuel injection timing setting completion flag Fz is “OFF” (S960).
[0114]
If Fz = “ON” (“NO” in S960), intake asynchronous injection is set (S940), and the process is temporarily terminated. However, since Fz = “OFF” is initially set (“YES” in S960). Next, it is determined whether or not the time D has elapsed (S970). This time D represents the continuation reference time of the intake synchronous injection setting (S930) that is executed after it is determined “YES” in step S950.
[0115]
If the time D has not elapsed (“NO” in S970), the intake-synchronized injection is then set (S930). Thus, the present process is temporarily terminated. As a result, fuel is injected from the fuel injection valves 24 to 38 during the intake stroke.
[0116]
If the time D has elapsed (“YES” in S970), then “ON” is set to the post-startup fuel injection timing setting completion flag Fz (S980), intake asynchronous injection is set (S940), and this process is temporarily performed. Exit.
[0117]
An example of control by the processing described above is shown in the timing chart of FIG.
The example of FIG. 15 shows a state where the vehicle is left in the garage for a long time by energizing the block heater 70 in a state where the engine 2 is stopped in a cold region, and the outside temperature THE becomes −30 ° C. . Although the cooling water temperature THW is maintained at 20 ° C. by the heat generated by the block heater 70, the intake air temperature THA is decreased to −20 ° C., and the AT hydraulic oil temperature ATH is decreased to −25 ° C.
[0118]
At time t <b> 20, the plug 70 a of the block heater 70 is removed from the outlet 72 a of the AC power source 72, and energization to the block heater 70 is stopped. Next, the ignition key is turned at time t21 to start cranking by the starter. At this time, the fuel injection amount Q is set based on the coolant temperature THW (= 20 ° C.). Thus, the required fuel injection amount Q is injected from the fuel injection valves 24 to 38 when the coolant temperature THW is 20 ° C.
[0119]
Then, the engine speed NE rises and once the start complete reference speed Ns is exceeded at time t12, the start is completed. However, at the fuel injection amount Q required at the coolant temperature THW = 20 ° C., stable combustion does not occur in some cylinders due to the temperature difference between the cylinders, so that the engine speed NE decreases rapidly immediately after this. Then, the engine speed NE falls below the decrease determination rotation speed NEL that is set higher than usual due to the inter-cylinder temperature difference generation flag Fh = “ON” until the determination standby time S elapses (time). t23).
[0120]
As a result, 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 high value. For this reason, when the temperature difference between cylinders has arisen, the fuel injection quantity Q of a required quantity will be injected from the fuel injection valves 24-38, and the combustion chamber will be in the air-fuel mixture state required for stable combustion. Thereafter, the fuel injection amount Q gradually decreases to the normal fuel injection amount, and shifts to the execution of idle speed feedback control and air-fuel ratio feedback control.
[0121]
Further, when the start-up fuel injection amount storage value Qa is updated in step S820 by the post-startup fuel injection timing setting process (FIG. 14), the intake synchronous injection is executed during the time D. . For this reason, the fuel injected toward the intake ports 8a to 22a by the fuel injection valves 24 to 38 is immediately drawn into the combustion chamber together with the intake air. Therefore, the amount of fuel attached to the intake ports 8a to 22a is reduced, and the fuel concentration in the combustion chamber can be increased.
[0122]
Note that, as in the past, if the decrease determination speed NEL remains low (shown in parentheses in FIG. 15), even if the fuel injection amount Q is determined only by the coolant temperature THW (= 20 ° C.), the engine speed immediately thereafter NE does not fall below the decrease determination rotational speed NEL. For this reason, the start time fuel injection amount storage value Qa is not updated, and the intake asynchronous injection remains unchanged. For this reason, the fuel injection amount Q remains considerably smaller than the required amount as indicated by the broken line, and the amount of adhesion by the intake synchronous injection is not reduced. There is a high risk of causing
[0123]
In the configuration of the second embodiment described above, steps S340 to 360 in the inter-cylinder temperature difference occurrence determination process (FIG. 7) are added to the process as the inter-cylinder temperature difference determination means. Steps S800 to S820 of the process (FIG. 11) and steps S950, S970, and S930 of the post-startup fuel injection timing setting process (FIG. 14) correspond to the process as the dilution suppression means.
[0124]
According to the second embodiment described above, the following effects can be obtained.
(I). If it is determined by the bad fuel increase process (FIG. 11) that the temperature difference between cylinders is large in the inter-cylinder temperature difference generation determination process (FIG. 7) when the engine 2 is started (in S740). “YES”), by increasing the decrease determination rotational speed NEL (S800), the starting fuel injection amount storage value Qa is updated to a larger value (S820), and the decrease in the fuel vapor concentration in the combustion chamber is suppressed. Yes.
[0125]
As a result, when the engine 2 is started, the set amount (S560) of the starting fuel injection amount stored value Qa is lowered because the coolant temperature THW is relatively high due to the operation of the block heater 70. Then, since the starting fuel injection amount storage value Qa is updated to a large value (S820), it is possible to suppress the fuel concentration in the combustion chamber from becoming thin.
[0126]
As described above, when the temperature difference between the cylinders is 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 reduced by the rough fuel increase process. By suppressing the fuel concentration, an appropriate fuel concentration can be obtained. Further, when the temperature difference between the cylinders is not large, a normal poor fuel increase process is performed, and an appropriate fuel concentration can be obtained by not suppressing the decrease in the fuel vapor concentration in the combustion chamber. Therefore, engine start control can be performed appropriately.
[0127]
(B). In the second embodiment, the lean fuel suppression process (FIG. 11) and the post-startup fuel injection timing setting process (FIG. 14) are utilized to realize the dilution control means.
[0128]
For this reason, since it can implement | achieve easily, without adding the change on a especially big system, manufacturing cost can be suppressed.
(C). The same effect as (b) of the first embodiment is produced.
[0129]
[Embodiment 3]
In the third embodiment, the 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, after the start shown in FIG. The fuel injection timing setting process and the catalyst warm-up ignition retard process shown in FIG. 19 are executed. Other configurations are the same as those in the first embodiment unless otherwise specified.
[0130]
The fuel injection amount control process (FIG. 16) will be described. In this fuel injection amount control process (FIG. 10), steps S1010, S1020, S1070 to S1170 are the processes of steps S110, S120, S170 to S270 in the fuel injection amount control process (FIG. 3) of the first embodiment. Is the same. In the third embodiment, the processing after it is determined at the start in step S1020 is different from that in the first embodiment.
[0131]
In other words, if it is determined that the engine is at the time of start (“YES” in S1020), the fuel injection amount Q at the time of start is calculated from the map shown in FIG. 4 of the first embodiment immediately based on the coolant temperature THW. (S1060). Next, it is determined whether or not the inter-cylinder temperature difference occurrence flag Fh is “ON” (S1062).
[0132]
If Fh = “OFF” (“NO” in S1062), the fuel injection amount Q obtained in step S1060 is set as the starting fuel injection amount storage value Qa (S1070), and further the fuel injection amount Q Is set as the valve opening time of the fuel injection valves 24 to 38 (S1080), and this process is temporarily terminated.
[0133]
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 ( S1064).
[0134]
[Equation 3]
Q ← Q + α ... [Formula 3]
Then, the increased fuel injection amount Q is set as a starting fuel injection amount storage value Qa (S1070), and this fuel injection amount Q is set as the valve opening time of the fuel injection valves 24-38 (S1080). Once this process is finished.
[0135]
Therefore, in the present fuel injection amount control process (FIG. 16), if the inter-cylinder temperature difference generation flag Fh is “ON”, the fuel injection amount Q obtained based on the coolant temperature THW is directly increased. .
[0136]
Next, the post-startup fuel injection timing setting process (FIG. 17) will be described. This process is a process that is repeatedly executed at regular time intervals.
When this process is started, it is first determined whether or not it is a start time (S1210). If it is at the time of starting (“YES” in S1210), “OFF” is set to the post-starting fuel injection timing setting completion flag Fz (S1220). Next, it is determined whether or not the time C has elapsed (S1230). This time C represents the continuation reference time of the intake synchronous injection setting (S1240) performed at the start. At first, since the fuel injection itself has not been executed yet, the time C has not elapsed ("NO" in S1230), and then the intake synchronous injection is set (S1240). Here, the intake synchronous injection is as described in the second embodiment. Thus, the present process is temporarily terminated.
[0137]
As a result, fuel is injected from the fuel injection valves 24 to 38 during the intake stroke, so that the injected fuel is immediately taken into the combustion chamber together with the intake air. At the time of start-up, the setting of intake synchronous injection (S1240) continues until time C has elapsed (“NO” in S1230). Then, when the time C has elapsed (“YES” in S1230), intake asynchronous injection is set (S1260). The intake asynchronous injection is as described in the second embodiment.
[0138]
Thus, the present process is temporarily terminated. As a result, since fuel is injected from the fuel injection valves 24 to 38 before the intake stroke, the fuel that has become vapor after adhering to the intake ports 8a to 22a once together with the intake air in the intake stroke. Inhaled.
[0139]
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 process (Embodiment 1: FIG. 7) is then set to “ON”. It is determined whether or not (S1250). When Fh = “OFF” (“NO” in S1250), that is, when the temperature difference between the cylinders is not a problem, intake asynchronous injection is set (S1260), and this process is temporarily terminated.
[0140]
On the other hand, if Fh = “ON” (“YES” in S1250), that is, if the temperature difference between the cylinders becomes a problem, then whether or not the post-startup fuel injection timing setting completion flag Fz is “OFF” is determined. It is determined (S1270).
[0141]
If Fz = “ON” (“NO” in S1270), intake asynchronous injection is set (S1260), and this process is temporarily terminated. However, since Fz = “OFF” is initially set (“YES” in S1270). Next, an average value Tab of the cooling water temperature THW and the intake air temperature THA is obtained as in the following equation 4 (S1280).
[0142]
[Expression 4]
Tab ← (THW + THA) / 2 [Formula 4]
Then, based on the average value Tab, the time E is calculated from the map showing the tendency in FIG. 18 (S1290). This time E represents the continuation reference time of the intake synchronous injection setting (S1240) executed after it is determined as “YES” in step S1250.
[0143]
Next, it is determined whether the time E has elapsed (S1300). If the time E has not elapsed (“NO” in S1300), the intake synchronous injection is set (S1240). Thus, the present process is temporarily terminated. As a result, fuel is injected from the fuel injection valves 24 to 38 during the intake stroke.
[0144]
If the time E has elapsed (“YES” in S1300), the post-startup fuel injection timing setting completion flag Fz is set to “ON” (S1310), intake asynchronous injection is set (S1260), and this process is temporarily performed. Exit.
[0145]
The catalyst warm-up ignition retarding process (FIG. 19) will be described. This process is a process that is repeatedly executed at regular time intervals.
When this process is started, first, the catalyst temperature Tcat is calculated (S1410). This calculation is based on the operating state 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, and the exhaust gas stored in the catalytic converter 68. The temperature of the purification catalyst is estimated. Instead of this, a temperature sensor may be arranged in the catalytic converter 68 to directly detect the catalyst temperature Tcat.
[0146]
Next, it is determined whether or not the catalyst temperature Tcat is equal to or higher than the catalyst activation reference temperature Tt (S1420). If Tcat ≧ Tt (“YES” in S1420), the process is temporarily terminated as it is.
[0147]
If Tcat <Tt (“NO” in S1420), it is next determined whether or not the inter-cylinder temperature difference generation flag Fh is “OFF” (S1430). If Fh = “OFF” (“YES” in S1430), the ignition timing retarding process for warming up the catalyst is executed because the temperature difference between the cylinders is not a problem (S1440). As a result, the exhaust gas from the combustion chamber is heated to activate the catalyst in the catalytic converter 68 at an early stage. Thus, the present process is temporarily terminated.
[0148]
On the other hand, if Fh = “ON” (“NO” in S1430), a problem temperature difference between the cylinders is generated and the combustibility is reduced, so that further deterioration of combustion is prevented. In addition, this process is temporarily terminated without executing the ignition timing retarding process.
[0149]
In the configuration of the third embodiment described above, steps S340 to 360 of the inter-cylinder temperature difference generation determination process (FIG. 7) are replaced by the processing as the inter-cylinder temperature difference determination means, and step S1062 of the fuel injection amount control process (FIG. 16). , S1064 and steps S1250, S1280 to S1300, S1240 of the post-startup fuel injection timing setting process (FIG. 17) correspond to the process as the dilution suppression means.
[0150]
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 in the inter-cylinder temperature difference occurrence determination process (FIG. 7) that the inter-cylinder temperature difference is large (“ YES ”), the fuel injection amount Q obtained at the coolant temperature THW is corrected to be increased (S1064). This can suppress a decrease in the fuel vapor concentration in the combustion chamber.
[0151]
As described above, when the temperature difference between the cylinders is large due to the operation of the block heater 70 when the engine 2 is started, the fuel in the combustion chamber is directly increased by the fuel injection amount Q. The reduction of the vapor concentration is suppressed. As a result, an appropriate fuel concentration can be obtained. If 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, engine start control can be performed appropriately.
[0152]
(B). Further, in the post-startup fuel injection timing setting process (FIG. 17), after the start of the engine 2 is completed, it is determined in the inter-cylinder temperature difference occurrence determination process (FIG. 7) that the inter-cylinder temperature difference is large ( In S1250 ("YES"), the intake synchronous injection is executed for the time E obtained by the average value Tab of the coolant temperature THW and the intake air temperature THA (S1240). This can more effectively suppress a decrease in the fuel vapor concentration in the combustion chamber. Therefore, the engine start control can be performed more appropriately.
[0153]
(C). If the inter-cylinder temperature difference increases, the fuel injection amount control process immediately increases the fuel injection amount Q and performs intake-synchronized injection directly. For this reason, it is possible to suppress a decrease in fuel vapor concentration due to an increase in fuel with a simple configuration.
[0154]
Therefore, since it can be easily realized without particularly changing the system, manufacturing cost can be suppressed.
(D). In the third embodiment, if the inter-cylinder temperature difference becomes large, the ignition timing retarding process for warming up the catalyst is not executed. As a result, the combustibility deterioration due to both the state where the temperature difference between the cylinders is large and the ignition timing retarded state are not combined, the rotational stability can be maintained, and the deterioration of the emission can be prevented.
[0155]
(E). The effect (b) of the first embodiment is produced.
[Other embodiments]
-It is good also as a structure which added the fuel injection timing setting process after starting (FIG. 14) with respect to the said Embodiment 1. FIG. Thereby, it is possible to further suppress the decrease in the fuel vapor concentration in the intake pipe and the combustion chamber.
[0156]
-It is good also as a structure which added the catalyst warm-up ignition retarding process (FIG. 19) with respect to the said Embodiment 1,2. As a result, a complex deterioration in combustibility can be prevented, so that rotation stability can be maintained and emission can be prevented from deteriorating.
[0157]
-It is good also as a structure which added the rough fuel increase process (FIG. 11) with respect to the said Embodiment 1,3. Thereby, it is possible to further suppress the decrease in the fuel vapor concentration in the combustion chamber.
[0158]
In the second and third embodiments, the intake-synchronized injection is performed for the time C at the start, but this process is not essential. In other words, the intake asynchronous injection may be performed during this period.
[0159]
In each of the above embodiments, the state in which the temperature difference between the cylinders is large due to the operation of the block heater 70 is determined based on the state of the cooling water temperature THW, the outside air temperature THE, and the AT hydraulic oil temperature ATH. (FIG. 7: S340 to S360). In addition to this, determination may be made only with the state of the cooling water temperature THW and the outside air temperature THE (S340, S350). Further, the oil temperature of engine oil which is a lubricating oil may be used instead of the AT hydraulic oil temperature ATH. Further, the intake air temperature THA may be used instead of the outside air temperature THE. Further, the fuel temperature may be used instead of the AT hydraulic oil temperature ATH or the oil temperature of the engine oil.
[0160]
In the fuel injection amount control process of the first embodiment (FIG. 3), in step S150 executed when the inter-cylinder temperature difference generation flag Fh = “ON”, the average value of the coolant temperature THW and the intake air temperature THA Was used to calculate the fuel injection amount Q. In addition, when the inter-cylinder temperature difference occurrence flag Fh = “ON”, the average value of the coolant temperature THW and the outside air temperature THE, the average value of the coolant temperature THW and the AT hydraulic oil temperature ATH, and the coolant temperature THW An average value of the engine oil temperature, an average value of the coolant temperature THW and the fuel temperature, or two or more of the coolant temperature THW and the outside air temperature THE, the AT hydraulic oil temperature ATH, the engine oil oil temperature, and the fuel temperature. Or the average value of all the temperatures including the coolant temperature THW, etc., etc. 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 coolant temperature THW.
[0161]
In each of the above embodiments, the block heater 70 and the cooling water temperature sensor 82 are disposed in the vicinity of the same single cylinder 8, but may be disposed in the vicinity of different cylinders. However, the state where the block heater 70 and the coolant temperature sensor 82 are arranged in the vicinity of the same one cylinder 8 more accurately detects a state in which the temperature difference between the cylinders due to energization of the block heater 70 is large. can do.
[0162]
In each of the above-described embodiments, the intake pressure sensor 76 is used. Instead, the intake air amount may be detected using various air flow meters. 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.
[0163]
Although the embodiments of the present invention have been described above, the embodiments of the present invention include embodiments of various technical items as described below in addition to the technical items described in the claims. It is noted that there is.
[0164]
(1). In addition to the structure according to claim 1,
When starting the internal combustion engine, if the inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large, execution of an ignition timing retarding process for warming up the exhaust purification catalyst is performed. An internal-combustion-engine control apparatus comprising ignition retard prohibiting means for prohibiting.
[0165]
Thus, when it is determined that the temperature difference between the cylinders is large, the ignition delay angle prohibiting means prohibits execution of the ignition timing retardation process for warming up the exhaust purification catalyst, thereby causing the inter-cylinder temperature. The combustibility deterioration due to both the large difference state and the ignition timing retardation is not combined. For this reason, rotation stability can be maintained and emission can be prevented from deteriorating.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of an engine in 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 map configuration explanatory diagram for obtaining a fuel injection amount Q based on a temperature variable T in the first embodiment.
FIG. 5 is a map configuration explanatory diagram for obtaining a basic fuel injection amount QBS based on the intake pressure PM and the engine speed NE in the first embodiment.
FIG. 6 is a map configuration explanatory diagram for obtaining a fuel injection amount cold correction coefficient Kq from the coolant 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.
9 is a timing chart illustrating an example of control according to Embodiment 1. FIG.
FIG. 10 is a flowchart of a fuel injection amount control process according to the second embodiment.
FIG. 11 is a flowchart of bad fuel increase processing according to the second embodiment;
12 is an explanatory diagram of a map configuration for obtaining a decrease determination rotational speed NEL from the coolant temperature THW in Embodiment 2. FIG.
13 is an explanatory diagram of a map configuration for obtaining a starting fuel injection amount storage value Qa from a coolant temperature THW in Embodiment 2. FIG.
FIG. 14 is a flowchart of post-startup fuel injection timing setting processing according to the second embodiment.
15 is a timing chart illustrating an example of control according to Embodiment 2. FIG.
FIG. 16 is a flowchart of fuel injection amount control processing according to the third embodiment.
FIG. 17 is a flowchart of post-startup fuel injection timing setting processing according to the third embodiment.
18 is a map configuration explanatory diagram for obtaining time E from an average value Tab of cooling water temperature THW and intake air temperature THA in Embodiment 3. FIG.
FIG. 19 is a flowchart of catalyst warm-up ignition retardation processing according to the third embodiment.
[Explanation of symbols]
2 ... Engine, 4, 6 ... Bank, 8, 10, 12, 14, 16, 18, 20, 22 ... Cylinder, 8a-10a, 12a, 14a, 16a, 18a, 20a, 22a ... Intake port, 8b, 10b , 12b, 14b, 16b, 18b, 20b, 22b ... exhaust port, 8c, 10c, 12c, 14c, 16c, 18c, 20c, 22c ... spark plug, 8d, 10d, 12d, 14d, 16d, 18d, 20d, 22d Igniter, 24, 26, 28, 30, 32, 34, 36, 38 ... fuel injection valve, 40, 42, 44, 46, 48, 50, 52, 54 ... intake manifold, 56 ... surge tank, 58 ... intake Path, 60 ... throttle valve, 60a ... throttle valve driving motor, 62 ... air cleaner, 64, 66 ... exhaust manifold, 67 ... exhaust pipe, 8 ... catalytic converter, 70 ... block heater, 70a ... plug, 72 ... AC power supply, 72a ... 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 ... Outside air temperature sensor, 94 ... Accelerator opening sensor, 96 ... Starter motor.

Claims (13)

An internal combustion engine control device for use in a multi-cylinder internal combustion engine provided with a heater that suppresses the 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 or not a temperature difference between the cylinders due to the operation of the heater is large when starting the internal combustion engine;
Cooling water temperature detecting means for detecting the temperature of the cooling water of the internal combustion engine;
When the internal combustion engine is started, when the inter-cylinder temperature difference determining means determines that the inter-cylinder temperature difference is large, the temperature is lower than the cooling water temperature detected by the cooling water temperature detecting means. Engine control means for performing engine control according to
An internal combustion engine control device comprising: An internal combustion engine control device for use in a multi-cylinder internal combustion engine provided with a heater that suppresses the 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 or not a temperature difference between the cylinders due to the operation of the heater is large when starting the internal combustion engine;
When the internal combustion engine is started, when the inter-cylinder temperature difference determining unit determines that the inter-cylinder temperature difference is large, the dilution suppression suppresses a decrease in the fuel vapor concentration in the intake pipe and the combustion chamber. Means,
An internal combustion engine control device comprising: 3. The configuration according to claim 1 or 2, wherein the inter-cylinder temperature difference determining means determines whether the inter-cylinder temperature difference is determined based on two or more types of detected values representing the temperature of the internal combustion engine or the atmospheric temperature of the internal combustion engine when starting the internal combustion engine. An internal combustion engine control device that determines whether or not a temperature difference is large. 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, or a hydraulic oil temperature of the transmission. Internal combustion engine control device. 4. The internal combustion engine control apparatus 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 fluid temperature of the transmission. 4. The internal combustion engine control apparatus according to claim 3, wherein 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. 4. The internal combustion engine control apparatus 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. 4. The internal combustion engine control apparatus 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 intake air temperature. 4. The internal combustion engine controller according to claim 3, wherein the detected values are a cooling water temperature and an outside air temperature of the internal combustion engine. In the configuration according to claim 2, the diluting suppression means uses a temperature obtained by correcting the detected cooling water temperature for the cold fuel increase process using the cooling water temperature of the internal combustion engine as a parameter. An internal combustion engine control apparatus characterized by suppressing a decrease in fuel vapor concentration in an intake pipe and a combustion chamber by increasing a fuel supply amount. 3. The configuration according to claim 2, wherein the dilution suppression means increases the reference rotational speed to increase the reference rotational speed in an increase processing when the engine rotational speed decreases when the engine rotational speed falls below the reference rotational speed immediately after starting. An internal combustion engine control device that suppresses a decrease in fuel vapor concentration in an intake pipe and in a combustion chamber by increasing a probability of execution of an increase processing when the number is reduced. 3. The configuration according to claim 2, wherein the diluting suppression unit directly executes a fuel increase process when the inter-cylinder temperature difference determining unit determines that the inter-cylinder temperature difference is large. An internal combustion engine control apparatus characterized by suppressing a decrease in fuel vapor concentration in an intake pipe and a combustion chamber. 3. The configuration according to claim 2, wherein the internal combustion engine is an intake port fuel injection type internal combustion engine in which fuel is injected into an intake port, and the dilution suppression means has a large temperature difference between cylinders in the inter-cylinder temperature difference determination means. An internal combustion engine control device that suppresses a decrease in the fuel vapor concentration in the combustion chamber by injecting fuel into the intake port during the intake stroke when it is determined that the fuel is in the intake stroke.

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