JP2009293446A - Engine start control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technology enabling accurate engine control in cold start during which an air-fuel ratio sensor is in a non-activated state. <P>SOLUTION: This device is provided with the air-fuel ratio sensor provided in an exhaust gas passage of the engine, a correction value calculation means starting the engine in warm start of the engine under a same operation condition as that in cold start by executing engine start for cold start, and calculating a correction value to be applied to engine control for cold start in order to make actual air-fuel ratio coincide to target air-fuel ratio based on comparison of a measurement value of the actual air-fuel ratio by the air-fuel ratio sensor at that time and target air-fuel ratio in cold start, and a cold start control means starting the engine by executing engine control for cold start corrected by the correction value calculated by the correction value calculation means in cold start of the engine. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine start control device.

  Variations in the fuel injection amount and the intake air amount occur due to individual differences in engine parts and changes in characteristics over time. A technique for learning this variation by measuring an actual air-fuel ratio with an air-fuel ratio sensor and correcting engine control such as fuel injection control and intake air amount control is known. However, it is difficult to perform such correction because the air-fuel ratio sensor is not activated when the engine is cold. Therefore, it is conceivable to correct the engine control in the cold state by using the learning result performed when the air-fuel ratio sensor is activated when the engine is warm and the air-fuel ratio sensor is inactive when the engine is cold.

As a related technique, at the time of cold start of the engine, the fuel injection amount is controlled by open loop control until the air-fuel ratio sensor is activated, and the control is switched to feedback control when activation of the air-fuel ratio sensor is detected. The technique is described in Patent Document 1.
JP 2004-197693 A JP 2005-120886 A JP 2000-54942 A

  If the engine control is the same during warm and cold conditions, such as when the engine is in steady operation, use the learning results during warm conditions to control the engine during cold conditions. Although correction can be made, if the contents of engine control differ between warm and cold, accurate engine control cannot be performed if such diversion is performed. For example, when the engine is started, it is a transient state in which the engine operating state such as rotation and load fluctuates with time. The mode of rotation and load fluctuation in the transient state is different between the cold start and the warm start. Therefore, the learning result performed during the warm start cannot be used for correcting the engine control during the cold start. For this reason, it has been difficult to accurately perform engine control at the time of cold start in which the air-fuel ratio sensor becomes inactive.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a technique that makes it possible to accurately perform engine control during cold start in which an air-fuel ratio sensor is in an inactive state. .

In order to achieve the above object, a start control device for an internal combustion engine of the present invention comprises:
An air-fuel ratio sensor provided in the exhaust passage of the engine;
At the time of warm start of the engine, engine control for cold start is performed to start the engine in the same operation state as at the time of cold start, and the measured value of the actual air fuel ratio by the air fuel ratio sensor at that time, Correction value calculation for calculating a correction value to be applied to the engine control for cold start in order to make the actual air fuel ratio coincide with the target air fuel ratio based on the comparison with the target air fuel ratio at the cold start Means,
Cold start control means for starting the engine by performing engine control for the cold start corrected by the correction value calculated by the correction value calculating means when the engine is cold started;
It is characterized by providing.

  Here, the warm start is an engine start performed in a situation where it is determined that the air-fuel ratio sensor is activated. The cold start is an engine start that is performed when the air-fuel ratio sensor is determined to be in an inactive state. For example, it is determined whether the engine is a warm start or a cold start based on information such as the coolant temperature of the engine, the outside air temperature, and the elapsed time since the last engine stop.

  In the present invention, the same engine behavior as that at the time of cold start is created at the time of warm start of the engine. At this time, since the engine is in a warm state, the air-fuel ratio sensor is in an activated state, and an accurate air-fuel ratio measurement can be performed. In this way, the difference between the actual air-fuel ratio and the target air-fuel ratio is resolved when the actual air-fuel ratio measured by creating the same engine behavior as during cold-start is measured as the actual air-fuel ratio during cold-start. As described above, a correction value for correcting the engine control for cold start is calculated.

  By correcting the engine control for cold start with the correction value calculated in this way, and performing the engine control after the correction at the actual cold start, the influence of variation in engine control at the cold start Can be suitably eliminated, and engine control during cold start can be performed with high accuracy.

  In the present invention, in order to create the same engine behavior at the time of warm start as at the time of cold start, intake air amount control and fuel injection control for cold start are performed at the time of warm start, and the engine speed is reduced. It is only necessary to start the engine by performing engine control so that the target rotational speed at the time of the intermediate start is achieved.

  Since the engine operating conditions (friction of moving parts, etc.) differ between the warm start and the cold start, the same intake air amount and fuel injection amount control as the cold start can be performed during the warm start. The engine speed may not be the target speed at the cold start. In such a case, feedback control may be performed so that the rotational speed matches the target rotational speed at the time of cold start by adjusting the ignition timing, for example. By doing so, it is possible to create a state in which the engine is started in the same operation state while performing the same engine control as in the cold start during the warm start.

In the present invention, the correction value calculation means calculates a correction value for correcting fuel injection amount control in the engine control for cold start,
The cold start control means performs fuel injection amount control for cold start using the fuel injection amount corrected by the correction value calculated by the correction value calculation means as a command value, and starts the engine. May be.

  The difference between the actual air-fuel ratio and the target air-fuel ratio is the individual difference of each fuel injector, the change in injection characteristics over time, the variation in characteristics of the throttle valve and idle speed control valve, the change over time, the influence of deposits in the intake system, etc. It happens due to various factors. By adopting the configuration as described above, the influence of various factors is absorbed in the correction value of the fuel injection amount in the fuel injection amount control, and the influence of variations in engine control during cold start is suitably eliminated. It becomes possible to do.

  Similarly, a correction value for correcting intake air amount control (for example, throttle opening control) in engine control for cold start is calculated by the correction value calculation means, and the intake air corrected by the calculated correction value is calculated. The engine may be started by performing intake air amount control for cold start using the amount as a command value.

  In the present invention, when calculating the correction value, as described above, engine control is performed so as to create an engine behavior at the time of cold start even at the time of warm start. When such control is performed, the fuel efficiency may be deteriorated at the time of warm start as compared with the case where the engine is started by performing engine control for normal warm start.

  Here, the correction value calculated by the correction value calculation means mainly includes control deviation caused by changes in control characteristics of the fuel injection injector, the throttle valve, etc. with time, and variations caused by individual differences in these engine components. Once the correction value is calculated, the period until the specific change over time becomes so large that it cannot be ignored in maintaining control accuracy is determined by the correction value calculated last time. Even if the corrected engine control for cold start is performed, the engine control for cold start with sufficiently high accuracy can be performed.

Therefore, in the present invention,
A determination unit that determines whether the correction value needs to be calculated by the correction value calculation unit based on a predetermined index that reflects a change in the engine characteristics over time;
During the period from when the correction value is calculated by the correction value calculation unit last time until the determination unit determines that the correction value needs to be calculated, the correction value calculation unit performs a warm start of the engine. Sometimes, the engine is started by performing normal warm start engine control, and the correction value may not be calculated.

  By doing so, the frequency of calculating the correction value by the correction value calculation means can be suppressed to the minimum necessary, so that deterioration in fuel consumption caused by calculation of the correction value can be suppressed.

  Here, the index reflecting the change over time is an index for estimating the degree of change over time such as the operating characteristics of the engine parts, and a predetermined allowable limit between the target air-fuel ratio and the actual air-fuel ratio in engine control. This is a parameter that can serve as a reference for determining that there is a possibility that an error exceeding 1 may occur. For example, the travel distance of the vehicle, the operating time of the engine, the integrated value of the fuel injection amount, and the like can be used as an indicator of changes over time. In this case, the determination unit needs to update the correction value calculated by the previous correction value calculation unit when, for example, the integrated value of the travel distance, the engine operating time, and the fuel injection amount exceeds a predetermined reference value. It can be determined that there is.

  In engine control, fuel injection control and intake air amount control can be corrected periodically by learning the injection characteristics of the fuel injection injector and learning the control characteristics of the throttle valve and idle speed control valve. is there. Such various learning results can also be used as a temporal change index. In this case, the determination means, for example, when the difference between the learning value of the injection characteristic of the injector when the learning by the learning means of the present invention is performed last time and the current value exceeds a predetermined reference value. It can be determined that the correction value learned by the previous learning means needs to be updated.

  When the present invention is applied to an engine starter capable of starting the engine by performing optimal engine control according to the engine water temperature at the time of cold start, the correction value calculating means of the present invention You may make it calculate the correction value which correct | amends the said engine control for every engine control content at the time of the cold start which changes according to water temperature.

For example, in the case of an engine starter configured to start an engine by dividing the engine water temperature during cold start into a plurality of temperature regions and performing engine control suitable for each temperature region, the correction value calculation of the present invention The means performs engine control adapted to cold start when the engine water temperature belongs to a certain temperature range at the time of engine warm start, and the engine is operated in the same operation state as at the time of cold start in the temperature range. The actual air-fuel ratio is made to coincide with the target air-fuel ratio on the basis of the comparison between the measured value of the actual air-fuel ratio by the air-fuel ratio sensor at that time and the target air-fuel ratio when cold-starting in the temperature range For this reason, it is preferable to calculate a correction value to be applied to engine control adapted to cold start in the temperature range. If such a correction value is calculated and learned for each of a plurality of temperature regions, it is possible to accurately and suitably perform engine control during cold start under all conditions.

  In this way, when calculating the correction value according to the engine water temperature at the time of cold start, the correction value suitable for one engine water temperature should be updated and the correction value suitable for another engine water temperature is updated. The timing to be performed does not always arrive at the same time. Only the correction value corresponding to the engine water temperature determined to be updated needs to be calculated and updated again by the correction value calculation means.

  Accordingly, whether or not the correction value calculation means needs to calculate (update) the correction value may be determined for each engine water temperature at the cold start. By doing so, it is possible to suppress deterioration in fuel consumption performance due to calculation of the correction value by the correction value calculation means at an unnecessarily high frequency.

  According to the present invention, it is possible to accurately perform engine control during cold start in which the air-fuel ratio sensor is in an inactive state.

  The best mode for carrying out the present invention will be described in detail below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  FIG. 1 is a diagram schematically showing a schematic configuration of an engine to which the engine start control device according to the present embodiment is applied and its intake system and exhaust system. A fuel injection valve 4 is provided so as to face the combustion chamber of the engine 1, and a spark plug 5 is provided. The fuel injection valve 4 is opened by an injection pulse signal from the ECU 11 and injects an amount of fuel proportional to the pulse width. A throttle device 3 for adjusting the intake air amount is provided in the intake passage 2 of the engine 1. The throttle device 3 includes a throttle valve that changes the passage area of the intake passage 2, a bypass passage that bypasses the throttle valve, an idle speed control (ISC) valve that is provided in the bypass passage, and each of the throttle valve and the ISC valve. And an actuator whose opening degree can be changed independently (the internal configuration of the throttle device 3 is not shown). An air flow meter 13 for measuring the intake air amount is provided in the intake passage 2 upstream of the throttle device 3.

  A catalytic converter 7 using a three-way catalyst is provided in the exhaust passage 6 of the engine 1. An air-fuel ratio sensor 16 is provided in the exhaust passage 6 upstream of the catalytic converter 7. In this embodiment, as the air-fuel ratio sensor 16, either a linear output type sensor or an oxygen sensor whose output continuously changes from the lean region to the rich region may be used. The air-fuel ratio sensor 16 is activated at a predetermined reference temperature or higher and functions as an air-fuel ratio sensor. In this embodiment, the state in which it can be determined that the air-fuel ratio sensor 16 is activated is referred to as “warm”, and the state in which it is possible to determine that the air-fuel ratio sensor 16 is in an inactive state. It will be referred to as “when cold”. In the system of the present embodiment, the determination as to whether it is warm or cold is made based on information such as the temperature of the air-fuel ratio sensor 16, the temperature of the exhaust gas passing through the air-fuel ratio sensor 16, the operating state of the engine 1, and the outside air temperature. It shall be comprised so that it can carry out based on.

  The engine 1 is provided with a crank angle sensor 12 that outputs a signal corresponding to the rotation angle of the crankshaft, a water temperature sensor 15 that measures the coolant temperature, and an accelerator opening sensor 14 that measures the accelerator opening. The crank angle sensor 12, the air flow meter 13, the accelerator opening sensor 14, the water temperature sensor 15, and the air / fuel ratio sensor 16 are electrically connected to the ECU 11, and signals output from the sensors are input to the ECU 11. In addition, the engine fuel injection valve 4, the spark plug 5, and the throttle device 3 are electrically connected to the ECU 11, and operations of these devices are controlled by control signals from the ECU 11. The ECU 11 grasps the operating state of the engine 1 and the driver's intention based on the signals input from the sensors, and transmits a control command value to each device accordingly.

  Due to individual differences of the fuel injection valve 4 and the throttle device 3 for each product and changes over time in the process of use, variations occur in the fuel injection characteristics of the fuel injection valve 4 and the control characteristics of the intake air amount by the throttle device 3. There is a case. For this reason, even if the fuel injection valve 4 and the throttle device 3 are controlled according to a predetermined control command value, the realized air-fuel ratio may deviate from the target air-fuel ratio.

  Therefore, the air-fuel ratio (actual air-fuel ratio) realized when engine control is performed according to a certain control command value is measured by the air-fuel ratio sensor 16, and the actual air-fuel ratio is determined based on the comparison between the actual air-fuel ratio and the target air-fuel ratio. The correction value to be applied to the control command value in order to match the target air-fuel ratio can be calculated, and the control command value corrected by the correction value can be used in the subsequent engine control. By periodically performing such correction, even when the engine characteristics change over time, it is possible to perform engine control with high accuracy over a long period of time.

  However, when the engine 1 is cold, the air-fuel ratio sensor 16 is in an inactive state, and an accurate air-fuel ratio measurement cannot be performed. Therefore, it is difficult to calculate a correction value based on the comparison between the measured value of the actual air-fuel ratio by the air-fuel ratio sensor 16 and the target air-fuel ratio for cold engine control. Therefore, for the engine control during the cold, the correction value calculated for the engine control during the warm is used to correct the engine control.

  In this way, the correction value calculated for the engine control during the warm time can be applied to the engine control during the cold time only when the engine control during the cold time is the same as that during the warm time. For example, when there is no significant difference between warm and cold, as in the case of engine control corresponding to steady operation, the cold The engine control can be corrected with sufficient accuracy.

  However, if the contents of the engine control differ between the warm time and the cold time, the correction value calculated for the warm engine control cannot be used for the cold engine control correction. For example, when the engine is started, it is a transient state in which the load and the rotational speed of the engine 1 fluctuate with time. The way of changing the load and the rotational speed in this transient state differs between the warm time and the cold time. Therefore, since the contents of the engine control differ between the warm start and the cold start, it is not possible to divert the correction value calculated for the engine control at the warm start to the correction of the engine control at the cold start. Can not. Therefore, there has been a problem that it is difficult to accurately perform engine control at the time of cold start.

Therefore, in the engine start control device of the present embodiment, during the warm start, the engine control for the cold start is performed to start the engine in the same operation state as during the cold start, and the air-fuel ratio sensor 16 at that time The measured value is regarded as the measured value of the actual air-fuel ratio at the cold start. The actual air-fuel ratio is made to coincide with the target air-fuel ratio on the basis of the measured value by the air-fuel ratio sensor 16, that is, the estimated value of the actual air-fuel ratio at the cold start and the target air-fuel ratio at the cold start. Therefore, a correction value to be applied to the control command value for engine control for cold start is calculated. Then, at the time of subsequent cold start, the control command value for engine control for cold start is corrected with the correction value, and the engine control is performed according to the corrected control command value.

The correction of the engine control at the cold start in this embodiment will be described with reference to FIGS. FIG. 2 shows that during warm start, engine control for cold start is performed to start the engine in the same operating state as during cold start (hereinafter also referred to as “warm cold start control”). It is a figure which shows an example of the time change of a throttle opening, ignition timing, a fuel injection amount, an engine speed, and an air fuel ratio in a case. 2, the engine control during cold start is initiated at time t _0. Specifically, as shown in FIG. 2 (A), the throttle opening is controlled to the throttle opening TAc for cold start, and the fuel injection amount is cold started as shown in FIG. 2 (C). The time base fuel injection amount Qc_base is controlled.

  Since the operating conditions of the engine 1 are different from those during the cold start, such as when the engine 1 is reduced in friction during the warm start, as shown in FIG. 2 (D), the engine speed is the target rotation during the cold start. There is a tendency that the rotational speed NEc is higher than the number NEc_trg. Therefore, as shown in FIG. 2B, by adjusting the ignition timing to an ignition timing SAc ′ that is retarded from the ignition timing SAc at the time of the original cold start, the engine speed is the same as that at the time of the cold start. Feedback control is performed so as to match the target rotational speed NEc_trg.

  By doing so, it is possible to create an operating state in which the throttle opening, the fuel injection amount, and the engine speed change in the same manner as during cold start during warm start. Therefore, it is considered that the air-fuel ratio measured by the air-fuel ratio sensor 16 in this state is an accurate estimated value of the air-fuel ratio realized at the cold start.

  Here, the base fuel injection amount Qc_base is a default fuel injection amount command value at the time of cold start stored in the ECU 11 in advance at the factory shipment stage. If the fuel injection characteristics of the fuel injection valve 4 are the same as those at the time of factory shipment, the target air-fuel ratio A / Fc_trg at the time of cold start should be realized by injecting fuel with the base fuel injection amount as a command value. . However, for example, the air-fuel ratio measured by the air-fuel ratio sensor 16 is the air-fuel ratio A / Fc that is shifted to the lean side from the target air-fuel ratio A / Fc_trg at the time of cold start, as shown in FIG. Suppose. In this case, it is presumed that the fuel injection characteristic of the fuel injection valve 4 is shifted to the side where the fuel injection amount is smaller than that at the time of factory shipment. That is, when fuel injection is actually performed at the base fuel injection amount Qc_base at the cold start, it can be estimated that an air-fuel ratio leaner than the target air-fuel ratio is realized.

  Therefore, the ratio α between the actual air-fuel ratio A / Fc (the air-fuel ratio measured by the air-fuel ratio sensor 16 at the time of execution of “warm cold start control”) and the target air-fuel ratio A / Fc_trg at the cold start is determined. Based on this ratio α, a correction value K (α) for correcting the base fuel injection amount Qc_base at the time of cold start can be calculated.

  FIG. 3 shows the control command value (in this case, the base fuel injection amount) for engine control for cold start, based on the correction value K (α) calculated as described above during actual cold start. It is a figure which shows an example of the time change of throttle opening, ignition timing, fuel injection amount, engine speed, and air fuel ratio when correct | amending and performing engine control according to the control command value after correction | amendment.

  Here, since the engine is actually started in the cold state, as shown in FIG. 3D, by igniting at the ignition timing SAc at the original cold start time as shown in FIG. The engine speed becomes the target speed NEc_trg at the time of cold start.

Further, as shown in FIG. 3C, here, the fuel injection amount Qc (= K (α) × Qc_base) obtained by correcting the base fuel injection amount Qc_base with the correction value K (α) is set at the time of cold start. As a final fuel injection amount command value, fuel injection control during cold start is performed. By performing such correction, as shown in FIG. 3E, it is possible to make the air-fuel ratio at the time of cold start coincide with the target air-fuel ratio A / Fc_trg. Therefore, it is possible to accurately perform engine control at the time of cold start.

  FIG. 4 is a flowchart showing a routine for performing engine start control of this embodiment. This routine is executed by the ECU 11 every time a start request for the engine 1 is generated.

  In step S101, the ECU 11 determines whether or not the correction value needs to be updated. Specifically, it is determined whether or not the index reflecting the change over time in the control characteristics of the engine 1 satisfies a predetermined condition. As an index reflecting the change over time, the travel distance of the vehicle after the previous correction value is calculated, the operating time of the engine 1, the integrated value of the fuel injection amount, and the like can be used. Then, it can be determined that the correction value needs to be updated when the travel distance, the operation time, the integrated value of the fuel injection amount, and the like exceed a predetermined reference value. Further, although not described in detail in the present embodiment, learning of the fuel injection characteristic and learning of the throttle control characteristic in the steady operation state at the warm time can be appropriately performed by a known technique. Transition can also be used as an indicator of changes over time. For example, in the system for learning the throttle control characteristic, the learning value of the throttle control characteristic at the time of calculating the correction value (correction value of the fuel injection amount control command value at the time of cold start) in the present embodiment is stored in the ECU 11. When the learning value is compared with the learning value of the latest throttle characteristic at the time of execution of this routine, both values are different from each other by a predetermined reference value or more (for example, 10% or more) In addition, the calculation of the correction value in the present embodiment can be executed again to determine that the correction value should be updated.

  If it is determined in step S101 that the correction value should be updated (Yes), the ECU 11 proceeds to step S102. In this case, the correction of the base fuel injection amount based on the correction value K (α) calculated and stored the last time can no longer sufficiently absorb the fuel injection characteristics of the fuel injection valve 4 and other variations. It means that change is progressing. If it is determined in step S101 that the correction value need not be updated (No), the ECU 11 proceeds to step S106. In this case, it means that the fuel injection amount at the time of cold start can be corrected with sufficient accuracy by correcting the base fuel injection amount with the correction value K (α) calculated and stored last time.

  In step S102, the ECU 11 determines whether or not the air-fuel ratio sensor 16 is activated. In other words, it is determined whether or not the engine 1 is in a warm state. As described above, this determination is made based on the engine water temperature, the outside air temperature, the elapsed time since the last engine stop, and the like. If it is determined in step S102 that the air-fuel ratio sensor 16 is activated (Yes), the ECU 11 proceeds to step S103. If it is determined in step S102 that the air-fuel ratio sensor 16 is in an inactive state (No), the ECU 11 proceeds to step S109.

  In step S103, the ECU 11 executes the above-mentioned warm start control during the warm time. That is, although it is a warm state, the same engine control as that at the time of cold start is performed, and the engine 1 is started in the same engine operating state as at the time of cold start.

  In step S <b> 104, the ECU 11 measures the air / fuel ratio by the air / fuel ratio sensor 16. As described above, the air-fuel ratio measured by the air-fuel ratio sensor 16 can be regarded as the actual air-fuel ratio at the cold start.

  In step S105, the ECU 11 calculates a correction value K (α) for correcting the base fuel injection amount. Specifically, as described above, based on the ratio α between the estimated value A / Fc of the actual air-fuel ratio at the cold start acquired in step S104 and the target air-fuel ratio A / Fc_trg at the cold start, A correction value K (α) is calculated as a correction value to be applied to the base fuel injection amount Qc_base in order to make the actual air-fuel ratio at the time of cold start coincide with the target air-fuel ratio A / Fc_trg.

  When a new correction value K (α) is calculated in step S105, processing such as resetting the count of the change index with time used in step S101 is appropriately performed.

  In step S101, it is determined that the correction value K (α) needs to be updated. However, if it is determined in step S102 that the air-fuel ratio sensor 16 is in an inactive state (step S101: Yes, step S102: No), the above-described warm start control cannot be executed, and therefore a new correction value K (α) cannot be calculated. In this case, the process proceeds to step S109, and cold start control is performed using the base fuel injection amount Qc_base as it is as a fuel injection command value (that is, without correction). Alternatively, cold start control is performed using a value obtained by correcting the base fuel injection amount using the previously calculated K (α) as a fuel injection command value.

  If it is determined in step S101 that it is not necessary to update the correction value K (α) (step S101: No), the process proceeds to step S106, and whether the air-fuel ratio sensor 16 is activated as in step S102. It is determined whether the engine 1 is in a warm state or a cold state. And when it determines with it being a warm state (step S106: Yes), ECU11 progresses to step S108 and performs normal warm start control. On the other hand, when it is determined that the engine is in the cold state (step S106: No), the ECU 11 proceeds to step S107, and the base fuel injection amount is calculated using the correction value K (α) that has already been calculated and stored in the ECU 11. Cold start control is performed using the corrected value as the fuel injection command value. As a result, as shown in FIG. 3, the actual air-fuel ratio at the time of cold start can be matched with the target air-fuel ratio A / Fc_trg, and the engine control at the time of cold start can be performed with high accuracy.

  In this embodiment, the fuel injection control at the cold start is corrected based on the ratio α between the air-fuel ratio measured at the cold start control at the warm time and the target air-fuel ratio at the cold start. Although described, the throttle opening degree control at the time of cold start may be corrected based on the ratio α. In short, it is only necessary to correct various control command values related to engine control during cold start so that the finally realized air-fuel ratio matches the target air-fuel ratio. The target fuel injection amount command value is merely an example of a control command value that can be a correction target.

  A second embodiment of the present invention will be described. The present embodiment has a plurality of cold start control patterns adapted for each engine water temperature at the cold start in the engine start control device of the first embodiment, and the plurality of the cold start control patterns according to the engine water temperature at the cold start. This is an embodiment in which the present invention is applied to a system configured to start an engine 1 by selecting an optimal control pattern from among the cold start control patterns. Constituent elements that are substantially the same as those of the first embodiment are given the same names and reference numerals as those of the first embodiment, and detailed descriptions thereof are omitted.

  The feature point of this embodiment is that there are a plurality of types of engine control patterns at the time of cold start. Therefore, for each engine control pattern, the cold start control at warm time is executed, and a correction value adapted to each engine control pattern This is a point that is calculated.

For example, the range of the engine water temperature that can be determined to be cold is defined as n temperature regions T (i).
(I = 1 to n), and when the engine water temperature T acquired at the cold start belongs to the i-th temperature region T (i), the engine water temperature region T (i) is adapted. A case where the present invention is applied to a system configured to start the engine 1 by performing engine control with the engine control pattern P (i) will be described.

  In this case, at the time of warm start, the engine 1 is started by performing engine control with the engine control pattern P (i) at the time of cold start that matches the engine water temperature region T (i), and the measurement by the air-fuel ratio sensor 16 at that time is performed. Based on the ratio α (i) between the value A / Fc (i) and the target air-fuel ratio A / Fc_trg (i) that conforms to the engine coolant temperature region T (i), it conforms to the engine coolant temperature region T (i). A correction value K (α (i)) for correcting the base fuel injection amount Qc_base (i) at the cold start is calculated. Such warm start control corresponding to the engine water temperature region T (i) is executed for all engine control patterns P (i) (i = 1 to n), and all engine control patterns P (i ), A correction value K (α (i)) is calculated.

  Then, at the time of cold start when the engine water temperature T actually belongs to the water temperature region T (i), a value obtained by correcting the base fuel injection amount Qc_base (i) by the correction value K (α (i)) is finally obtained. As a fuel injection command value, engine control during cold start is executed.

  By doing so, the present invention can be preferably applied even in a system configured to change the pattern of the cold start control more finely according to the engine water temperature at the cold start. Therefore, it is possible to execute the engine control at the cold start accurately and suitably under all conditions of the engine water temperature.

  In this embodiment, since it is necessary to calculate the correction value K (α (i)) (i = 1 to n) equal to the number of divisions (n) of the temperature region, each correction value K (α ( Regarding i)), it is necessary to update appropriately based on the index of change over time. Here, the warm-time cold start control corresponding to the temperature region T (i) is executed again based on the timing at which each correction value K (α (i)) needs to be updated, in other words, based on the index of change over time. Thus, the timing at which it is determined that the correction value K (α (i)) needs to be calculated does not necessarily arrive at the same time for each correction value K (α (i)).

  Therefore, in the case of the present embodiment, the routine shown in FIG. 4 of Embodiment 1 is executed for each temperature region T (i) to which the engine coolant temperature belongs. That is, before the execution of the step corresponding to step S101, the step of measuring the engine water temperature and acquiring which temperature region it belongs to is executed and updated for each correction value K (α (i)). Judgment was made on whether it was necessary.

  For example, when it is necessary to update a certain correction value K (α (i)) and no correction is necessary for another correction value K (α (j)), the measured engine water temperature is in the temperature region T (j ), A negative determination is made in the step corresponding to step S101, and the process proceeds to the step corresponding to step S106. In this case, the fact that the engine water temperature belongs to T (j) means that it is in a cold state, so a negative determination is made in the step corresponding to step S106, and the step corresponding to step S107 is executed. Is done. That is, the engine control pattern P (j) at the time of cold start that matches the temperature region T (j) is executed, and the fuel injection amount command value Qc (j) at that time is already obtained and stored in the ECU 11. Is set to a value obtained by correcting the base fuel injection amount Qc_base (j) by the correction value K (α (j)).

On the other hand, when the measured engine water temperature belongs to the temperature region T (i), an affirmative determination is made in a step corresponding to step S101, and the process proceeds to a step corresponding to step S102. In this case, the fact that the engine water temperature belongs to T (i) means that it is in a cold state, so a negative determination is made in the step corresponding to step S102, and the step corresponding to step S109 is executed. Is done. In this case, at the subsequent warm start, a flag is set so that the warm cold start control for calculating the correction value K (α (i)) suitable for the temperature region T (i) is executed. Such processing may be executed as appropriate.

  In this way, by determining whether or not updating is required for each correction value K (α (i)), it is not necessary to calculate a correction value by unnecessarily high frequency warm start control. Further, it is possible to suppress the deterioration of the fuel consumption performance due to the execution of the cold start control during the warm time.

  In the present embodiment, the ECU 11 that executes Steps S103 to S105 in FIG. 4 corresponds to the correction value calculation means in the present invention. Moreover, ECU11 which performs step S108 of FIG. 4 is corresponded to the cold start control means in this invention. Moreover, ECU11 which performs step S101 of FIG. 4 is equivalent to the determination means in this invention.

It is a figure which shows schematic structure of the engine which applies the engine start control apparatus in an Example, and its intake / exhaust system. In the first embodiment, at the time of the warm start, the engine control for the cold start is performed to start the engine in the same operation state as at the cold start, the throttle opening, the ignition timing, the fuel injection amount, the engine It is a figure which shows an example of the time change of a rotation speed and an air fuel ratio. In the first embodiment, the control command value (base fuel injection amount) for engine control for cold start is corrected by the calculated correction value, and engine control is performed according to the corrected control command value at cold start. FIG. 6 is a diagram showing an example of a time change in throttle opening, ignition timing, fuel injection amount, engine speed, and air-fuel ratio in a case where 3 is a flowchart illustrating a routine for performing engine start control according to the first embodiment.

Explanation of symbols

1 Engine 2 Intake Passage 3 Throttle Device 4 Fuel Injection Valve 5 Spark Plug 6 Exhaust Passage 7 Catalytic Converter 11 ECU
12 Crank angle sensor 13 Air flow meter 14 Accelerator opening sensor 15 Water temperature sensor 16 Air-fuel ratio sensor

Claims (6)

An air-fuel ratio sensor provided in the exhaust passage of the engine;
At the time of warm start of the engine, engine control for cold start is performed to start the engine in the same operation state as at the time of cold start, and the measured value of the actual air fuel ratio by the air fuel ratio sensor at that time, Based on the comparison with the target air-fuel ratio at the time of cold start, correction value calculation for calculating a correction value to be applied to the engine control for cold start in order to make the actual air-fuel ratio coincide with the target air-fuel ratio Means,
Cold start control means for starting the engine by performing engine control for the cold start corrected by the correction value calculated by the correction value calculation means when the engine is cold started;
An engine start control device comprising: 2. The correction value calculating means according to claim 1, wherein during the warm start of the engine, the intake air amount control and the fuel injection amount control for the cold start are performed, and the engine rotational speed is the target rotational speed at the cold start. An engine start control device characterized by starting the engine by performing engine control so that In claim 1 or 2,
The correction value calculating means calculates a correction value for correcting fuel injection amount control in the engine control for cold start,
The cold start control means performs the fuel injection amount control for cold start using the fuel injection amount corrected by the correction value calculated by the correction value calculation means as a command value, and starts the engine. An engine start control device. In any one of Claims 1-3,
A determination unit that determines whether the correction value needs to be calculated by the correction value calculation unit based on a predetermined index that reflects a change in the engine characteristics over time;
During the period from when the correction value is calculated by the correction value calculation unit last time until the determination unit determines that the correction value needs to be calculated, the correction value calculation unit performs a warm start of the engine. Sometimes, the engine start control device is configured to start the engine by performing normal warm start engine control and not calculate the correction value. In any one of Claims 1-4,
The engine control content for the cold start differs according to the engine water temperature at the cold start,
The engine start control device characterized in that the correction value calculation means calculates the correction value for each control content at the time of cold start which varies depending on the engine water temperature. In claim 5,
The determination means determines whether or not the correction value needs to be calculated by the correction value calculation means for each control content at a cold start that varies depending on the engine water temperature. Start control device.

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