JP2007309264A - Vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress emission deterioration, exhaust odor and deterioration of fuel economy in a catalyst warming-up process. <P>SOLUTION: This vehicle control device is provided with a control circuit 30 for controlling a vehicle provided with an internal combustion engine 1 having an exhaust gas purifying catalyst 25 in accordance with the warming-up condition of the catalyst 25. This control circuit 30 is provided with a catalyst temperature estimating means for estimating the temperature of the catalyst 25 at start of the engine 1 based on the engine cooling water temperature at start of the engine 1, and limits upshift of an automatic transmission as the estimated catalyst temperature decreases. By making the automatic transmission at a lower stage by this upshift limitation, catalyst warming-up performance is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vehicle control device, and more particularly, to a vehicle control device capable of suppressing emission deterioration, exhaust odor suppression, and fuel consumption deterioration during a catalyst warm-up process.

  Conventionally, an exhaust gas purification apparatus having a catalyst for purifying harmful components in exhaust gas is provided in an exhaust passage of an internal combustion engine. A catalyst such as a three-way catalyst used in such an exhaust purification device does not exhibit exhaust purification ability unless it reaches a certain temperature (activation temperature) or higher. Therefore, at the time of cold start of the engine, so-called catalyst warm-up control is performed in which the temperature of the exhaust gas that passes through the catalyst is raised so that the catalyst temperature quickly reaches the activation temperature.

  As such conventional warm-up control, for example, the amount of change in the gear ratio of the continuously variable transmission is determined according to the difference between the catalyst temperature and the target catalyst temperature, and the target catalyst temperature is quickly reached by changing the gear ratio. A technique for matching is proposed (see Patent Document 1).

  Further, a technique has been proposed in which when the catalyst temperature becomes higher than the set catalyst temperature, the throttle restriction is canceled and the warm-up is terminated early (see Patent Document 2). Furthermore, a technique for performing fuel cut control when the catalyst temperature is equal to or lower than a predetermined value has been proposed (see Patent Document 3).

  In addition, a technique for performing catalyst warm-up control such as retarding the ignition timing is also known. However, when such warm-up control is performed, there is a risk of deterioration in drivability and increase in fuel efficiency due to a decrease in engine output. The warming-up operation is preferably terminated immediately after the catalyst warm-up is completed.

  For this purpose, a temperature sensor for detecting the catalyst temperature may be arranged on the catalyst bed so that when the detected catalyst temperature reaches a predetermined activation temperature, it is determined that the catalyst warm-up has been completed. Although it is possible, it is not preferable to provide a new temperature sensor for the catalyst because it complicates the apparatus and increases the cost.

  Therefore, the applicant of the present application can accurately determine the catalyst warm-up state by accurately estimating the amount of heat given to the catalyst from the engine exhaust and determining the catalyst warm-up state. An apparatus is provided (see Patent Document 4). For example, the control device estimates the catalyst temperature at the time of starting the engine based on the temperature of the engine coolant at the time of starting the engine, and accurately estimates the amount of heat given to the catalyst from the engine exhaust based on the estimated catalyst temperature. It is composed.

JP 2001-235019 A JP-A-6-146955 JP 2005-247871 A JP-A-7-229419

  However, in the conventional vehicle control apparatus, in the catalyst warm-up process after the cold start of the internal combustion engine, the catalyst effective (active) capacity increases as the catalyst warm-up proceeds. Therefore, in the catalyst warm-up process immediately after the cold start, the catalyst atmosphere becomes rich (hereinafter, abbreviated as “catalyst-rich” as appropriate) even if the air-fuel ratio becomes slightly rich, and the emission deteriorates. Further, there has been a problem in that sulfur and hydrogen adsorbed on the catalyst may react to generate an exhaust odor of hydrogen sulfide.

  The reason why the emission deteriorates in this way is that the so-called wall surface of the fuel is often attached in the cold state, so that the catalyst is more likely to become rich as the vehicle deceleration increases. Moreover, in order to suppress misfire at the time of light load deceleration of the engine, control is performed to increase the fuel injection amount at light loads and at low temperatures.

  In addition, control for prohibiting the shift-up of the transmission to a higher gear side is also known when it is cold, but as a result of performing such control, fuel cut control at the time of deceleration is executed due to lower gear (low gear). Although it is easy to operate and advantageously works to suppress the exhaust odor, there is a possibility that problems such as deterioration in fuel consumption and engine noise due to lowering of the stage may occur.

  In addition, the engine coolant temperature (or oil temperature) and the catalyst temperature are not related to each other in all the driving conditions in the warm-up process, so the emission deterioration and the exhaust odor in various vehicle driving conditions in the warm-up process. In order to suppress the deterioration and the deterioration of fuel consumption, optimum control according to the catalyst temperature has been demanded.

  The present invention has been made in view of the above, and an object of the present invention is to provide a vehicle control device that can suppress emission deterioration, exhaust odor suppression, and fuel consumption deterioration in the catalyst warm-up process.

  In order to solve the above-described problems and achieve the object, a vehicle control apparatus according to a first aspect of the present invention sets a vehicle equipped with an internal combustion engine having an exhaust purification catalyst to a warm-up state of the catalyst. A control apparatus for a vehicle provided with a control device that controls the engine according to the present invention further comprises catalyst temperature estimation means for estimating a catalyst temperature at the start of the engine based on at least the engine coolant temperature at the start of the engine. The control is performed based on the estimated catalyst temperature by the catalyst temperature estimating means.

  According to a second aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the vehicle includes an automatic transmission having a plurality of speed stages, and the control is performed by the estimated catalyst temperature. The lower the limit, the more limited the upshifting of the automatic transmission.

  According to a third aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the vehicle includes an automatic transmission having a torque converter with a lock-up mechanism. As the estimated catalyst temperature is lower, the lock-up is prohibited.

  According to a fourth aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the internal combustion engine is subjected to fuel cut control in which fuel supply is stopped under a predetermined condition. The control is characterized in that the lower the estimated catalyst temperature, the lower the engine speed when returning from the fuel cut control and restarting the fuel supply.

  According to a fifth aspect of the present invention, there is provided a vehicle control device according to the first aspect, wherein the internal combustion engine is subjected to fuel cut control in which fuel supply is stopped under a predetermined condition. The control is characterized in that the fuel cut delay time, which is a threshold value when the fuel cut control is performed, is shortened as the estimated catalyst temperature is lower.

  According to a sixth aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the internal combustion engine is subjected to throttle opener control for opening a throttle valve under a predetermined condition. The control is characterized in that the throttle opener amount is increased as the estimated catalyst temperature is lower.

  According to a seventh aspect of the present invention, there is provided a vehicle control apparatus according to the sixth aspect, wherein the ignition timing is retarded as the throttle opener amount increases.

  According to an eighth aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the internal combustion engine performs idle speed control by adjusting a control amount of an idle speed control valve under a predetermined condition. The control is performed, and the control amount of the idle speed control valve is increased as the estimated catalyst temperature is lower.

  According to a ninth aspect of the present invention, there is provided a vehicle control apparatus according to the first aspect, wherein the internal combustion engine performs a light load increase control for increasing a fuel injection amount at a light load immediately after a cold start. The control is characterized in that the increase rate is decreased as the estimated catalyst temperature is lower.

  According to a tenth aspect of the present invention, in the control device for a vehicle according to the first aspect, the internal combustion engine performs fuel cut control in which fuel supply is stopped or restarted under a predetermined condition, When the fuel cut is released and the fuel supply is started, the fuel injection amount is controlled to increase. The control decreases the amount of the increase control as the estimated catalyst temperature is lower. Is.

  According to an eleventh aspect of the present invention, in the vehicle control apparatus according to the tenth aspect, the internal combustion engine includes a deterioration degree determining means for determining the degree of deterioration of the catalyst, and the deterioration degree determining means. The amount of the increase control is increased and corrected as the degree of deterioration due to is increased.

  According to the vehicle control device of the present invention (claim 1), various controls can be optimally performed in accordance with the exact active state (warm-up state) of the catalyst. It is possible to effectively suppress odor suppression and fuel consumption deterioration.

  Moreover, according to the vehicle control apparatus (claim 2) of the present invention, the catalyst warm-up property can be improved by the low gear by the shift-up restriction.

  Further, according to the vehicle control apparatus (claim 3) of the present invention, the catalyst warm-up property can be improved by the low gear by performing the lock-up control.

  Further, according to the vehicle control apparatus (Claim 4) according to the present invention, the fuel cut condition can be expanded in a direction in which the fuel cut control is more easily performed as the catalyst temperature is lower. The catalyst is made lean, and emission deterioration and exhaust odor can be suppressed.

  In addition, according to the vehicle control apparatus of the present invention (Claim 5), the fuel cut delay time can be shortened as the catalyst temperature is lowered, and the fuel cut condition can be expanded in a direction in which fuel cut control can easily be entered. In addition to being able to suppress fuel consumption deterioration, the catalyst is leaned, and emission deterioration and exhaust odor can be suppressed.

  Further, according to the vehicle control apparatus (Claim 6) of the present invention, after the cold start, the catalyst is made leaner by strengthening the throttle opener control as the catalyst temperature is lower. Can be suppressed. Further, after the catalyst is warmed up, the deterioration of fuel consumption can be suppressed by reducing the throttle opener amount.

  Moreover, according to the vehicle control apparatus (claim 7) according to the present invention, it is possible to suppress the deterioration of the feeling of deceleration.

  In addition, according to the vehicle control apparatus of the present invention (Claim 8), after the cold start, as the catalyst temperature is lower, idle strengthening is performed, so that the adhesion of the fuel to the intake manifold wall surface is suppressed, and the emission is deteriorated. Exhaust odor can be suppressed. Further, after the catalyst is warmed up, deterioration of fuel consumption can be suppressed by reducing the control amount of the idle speed control valve.

  In addition, according to the vehicle control apparatus of the present invention (Claim 9), after the cold start, the catalyst rich state is suppressed when the estimated catalyst temperature is low, and emission deterioration and exhaust odor can be suppressed. , Deterioration of fuel consumption can be suppressed.

  According to the vehicle control apparatus (claim 10) of the present invention, after the cold start, when the estimated catalyst temperature is low, the catalyst rich state is suppressed, and emission deterioration and exhaust odor can be suppressed. , Deterioration of fuel consumption can be suppressed.

  According to the vehicle control device of the present invention (claim 11), the fuel injection amount is corrected to increase as the degree of deterioration of the catalyst increases when the fuel supply is resumed. Warm up early.

  Embodiments of a vehicle control apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  FIG. 1 is a schematic diagram showing a vehicle control apparatus according to Embodiment 1 of the present invention. In FIG. 1, 1 is an internal combustion engine, 2 is a piston, 3 is a combustion chamber, and 4 is a spark plug. The intake port 5 of the internal combustion engine 1 is connected to a surge tank 7 via an intake manifold 6, and further connected to an air cleaner 9 from the surge tank 7 via an intake passage 8.

  The intake passage 8 is provided with an air flow meter 12 that generates a voltage signal proportional to the engine intake air flow rate. Further, a throttle valve 10 is provided between the air flow meter 12 and the surge tank 7 to take an opening according to the driver's accelerator pedal (not shown) operation.

  The intake air temperature sensor 13 is built in the air flow meter 12 and generates a voltage signal corresponding to the intake air temperature. The cooling water temperature sensor 14 is disposed in the cooling water passage of the internal combustion engine 1 and generates a voltage signal corresponding to the cooling water temperature.

  The intake manifold 6 is provided with a fuel injection valve 11 that injects an amount of fuel into each intake port 5 in accordance with a signal from a control circuit (vehicle control device) 30 described later. On the other hand, the exhaust port 21 is connected to an exhaust passage 23 via an exhaust manifold 22, and the exhaust passage 23 has a three-way catalyst (hereinafter referred to as “three-way catalyst” that can simultaneously purify three components of HC, CO, and NOx in the exhaust. Abbreviated as “catalyst.”) 25 is arranged. In the present embodiment, the three-way catalyst 25 is exemplified as the catalyst device. However, the present invention is not limited to this, and other catalysts may be used.

  The control circuit 30 is a digital computer having a known configuration in which a ROM (Read Only Memory) 32, a RAM (Random Access Memory) 33, a CPU (Microprocessor) 34, and input / output ports 35 and 36 are connected to each other via a bidirectional bus 31. The basic control of the internal combustion engine 1 such as the fuel injection amount and the ignition timing is performed.

  Further, the control circuit 30 functions as a catalyst temperature estimating means described later as a vehicle control device, and also functions as a means for executing various controls described later.

  For these controls, a voltage signal representing the intake air amount from the air flow meter 12 and a voltage signal representing the engine intake air temperature from the intake air temperature sensor 13 are fed to the AD converter 37 at the input port 35 of the control circuit 30. Is entered through. The intake air temperature signal is used to correct the temperature of the intake air amount detected by the air flow meter 12, and is also used to estimate the catalyst temperature when the engine is started.

  Further, the input port 35 of the control circuit 30 is further supplied with a voltage signal representing the cooling water temperature from the cooling water temperature sensor 14 via the AD converter 37, and is provided in an engine distributor (not shown). A pulse signal is input from the crank angle sensor 41 for each fixed engine crankshaft rotation angle. This pulse signal is used not only for calculating the engine speed but also as a reference signal for engine ignition timing.

  On the other hand, the output port 36 of the control circuit 30 is connected to the spark plug 4 through an ignition circuit 38 to control the engine ignition timing, and is connected to the fuel injection valve 11 through a drive circuit 39, so that the fuel injection amount is controlled. Is controlling.

  That is, the control circuit 30 calculates the ignition timing from the engine load, the rotational speed, etc., and outputs the ignition signal to the ignition circuit 38 so that the ignition timing is obtained based on the reference pulse signal input from the crank angle sensor 41. .

  Further, the control circuit 30 performs a fuel injection amount calculation based on the engine intake air amount, the rotational speed, and the like, and sets the valve opening time (injection time) of the fuel injection valve 11 according to the calculated fuel injection amount. In addition, the control circuit 30 performs control for stopping the supply of fuel during deceleration, so-called fuel cut control, under a predetermined condition in order to improve fuel efficiency.

  Next, a control method will be described with reference to FIG. Here, FIG. 2 is a flowchart showing a control method. It is known that when cold (cooling water temperature or oil temperature is low), control (shift guard control) is performed to prohibit shift-up of the transmission to the high gear stage side. This shift guard control is performed to improve catalyst warm-up by low gear and to expand fuel cut control during deceleration (exhaust odor suppression by making the catalyst lean).

  However, in the conventional shift guard control based on the cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. For this reason, in shift guard control based on the cooling water temperature, in order to reliably determine the active state (catalyst warm-up) of the catalyst 25 in any running state, a limit value for prohibiting upshifting is set to the cooling water temperature. Since it is necessary to set to the high temperature side, there is a possibility that the fuel consumption deterioration area may be expanded.

  Therefore, in the first embodiment, not the shift guard control based on the cooling water temperature but the shift guard control based on the estimated catalyst temperature is performed, and as described later, the shift up is limited as the catalyst temperature is lower. Shift guard control can be performed according to the catalyst warm-up condition.

  The method for estimating the catalyst temperature is disclosed in the above-mentioned Patent Document 4 by the applicant of the present application, and detailed description thereof is omitted. For example, it can be calculated as follows. That is, there is a correlation between the temperature drop of the cooling water after the internal combustion engine 1 is stopped and the temperature drop of the catalyst 25, and the temperature of the catalyst 25 can be estimated from the cooling water temperature after the engine is stopped.

  Therefore, if the relationship between the coolant temperature after stopping the engine and the catalyst temperature is stored in advance in the ROM 32 of the control circuit 30 as a map, the catalyst temperature at the time of engine start is determined from this map by detecting the coolant temperature. can do. Note that the relationship between the cooling water temperature and the catalyst temperature varies depending on the shape of the exhaust passage 23, the arrangement of the catalyst 25, and the like, and thus is determined in advance through experiments or the like.

  Further, the catalyst temperature may be estimated as follows. Since the catalyst 25 arranged in the exhaust passage 23 is easily affected by the outside air temperature, when the outside air temperature changes, the temperature drop rate changes more than the cooling water. Therefore, in order to accurately estimate the catalyst temperature when starting the engine, it is preferable to consider the influence of the outside air temperature.

  Therefore, if the relationship between the outside air temperature, the cooling water temperature, and the catalyst temperature is stored in advance in the ROM 32 of the control circuit 30 as a map, the outside air temperature and the cooling water temperature are detected, and the catalyst at the time of engine start is detected from this map. The temperature is determined more accurately.

  In the cold guard control according to the first embodiment, as shown in FIG. 2, first, it is determined whether or not the vehicle is traveling (step S10). If the vehicle is not traveling (No at Step S10), the shift-up is not performed, and the routine is left out of the present routine because it is outside the scope of this control.

  If the vehicle is running (Yes at Step S10), for example, as shown in FIG. 3, shift guard control is performed to limit the upshifting as the estimated catalyst temperature is lower (Step S11). Here, FIG. 3 is a map showing the shift position upper limit guard based on the estimated catalyst temperature, and the relationship between the estimated catalyst temperature and the shift upper limit position guard is obtained in advance through experiments or the like.

  Accordingly, the warm-up performance of the catalyst is improved by the low gear, and if the known fuel cut control is performed at the time of deceleration, the fuel cut region is expanded, so that deterioration of fuel consumption can be further suppressed and the catalyst 25 is made lean. It is possible to suppress emission deterioration and exhaust odor.

  In the first embodiment, the description has been given by taking the case where the gear stage is the fifth speed in FIG. 3 as an example, but the present invention is not limited to this, and may be, for example, the fourth speed or the fifth speed.

  In a vehicle equipped with an automatic transmission (AT) having a plurality of speed stages, control (lock-up control) that prohibits lock-up may be performed when the vehicle is cold (cooling water temperature or oil temperature is low). Are known. In other words, “lock-up control” here refers to operating the torque converter from the converter state in which the direct connection between the input / output elements is released to the lock-up state in which the input / output elements are directly connected by fastening the lock-up clutch. That means.

  This lock-up control is performed for improving the catalyst warm-up performance by using a low gear and for expanding the fuel cut control during deceleration (suppressing exhaust odor by making the catalyst lean).

  However, in the conventional lockup control based on the cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. For this reason, in the lockup control based on the cooling water temperature, in order to reliably determine the active state (catalyst warm-up) of the catalyst 25 in any running state, a limit value for prohibiting the lockup is set to the cooling water temperature. Since it is necessary to set to the high temperature side, there is a possibility that the fuel consumption deterioration area may be expanded.

  Therefore, in this second embodiment, lockup control based on the estimated catalyst temperature is performed instead of lockup control based on the cooling water temperature, and lockup is prohibited as the catalyst temperature is lower as described later. The lockup control according to the catalyst warm-up state can be performed. Hereinafter, this lockup control will be specifically described.

  FIG. 4 is a flowchart showing a control method according to Embodiment 2 of the present invention. In the following description, the same or corresponding parts as those already described and the step numbers are denoted by the same reference numerals, and redundant description is omitted or simplified.

  As shown in FIG. 4, it is first determined whether or not the vehicle is traveling (step S10). If the vehicle is not running (No at Step S10), the lock-up control is not performed, and the control routine is outside the scope of this control.

  If the vehicle is running (Yes at Step S10), for example, as shown in FIG. 5, lock-up control is performed to prohibit lock-up as the estimated catalyst temperature is lower (Step S21). Here, FIG. 5 is a map showing the lockup characteristics based on the estimated catalyst temperature, and the allowed range and prohibited range of the lockup are obtained in advance by experiments or the like according to the estimated catalyst temperature.

  Therefore, by performing the lockup control in this way, the catalyst warm-up property is improved by the low gear. Further, if the known fuel cut control is performed at the time of deceleration, the fuel cut region is expanded, so that deterioration of fuel consumption can be suppressed, and the catalyst 25 is leaned to suppress emission deterioration and exhaust odor. be able to.

  In the fuel cut control described above, the supply of fuel is stopped when the engine speed enters a predetermined range during deceleration while the engine is idling.

  Specifically, the fuel supply is stopped when the throttle valve is closed while the engine is running and the engine speed gradually decreases and becomes less than the fuel cut engine speed that defines the upper limit of the range. When the engine speed further decreases and reaches the return engine speed that defines the lower limit of the range, the fuel supply is resumed.

  The return engine speed is set to a speed that does not cause engine stall and maintains stable engine rotation. From the viewpoint of improving fuel efficiency, it is desirable that the engine speed after the fuel cut is set low and the fuel is cut as long as possible.

  Such fuel cut control is basically executed based on the engine speed. Further, the conventional return engine speed (hereinafter abbreviated as “F / C return engine speed”) has been calculated based on the coolant temperature as shown in the map of FIG. Here, FIG. 7 is a map showing the characteristics of the F / C return engine speed based on the conventional cooling water temperature.

  However, in the control based on the conventional cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. For this reason, in the control based on the cooling water temperature, in order to reliably determine the active state (catalyst warm-up) of the catalyst 25 in any running state, the lower the cooling water temperature, the higher the return engine speed is set. There is a need. Moreover, since it is necessary to set the rotational speed higher than actually required from the viewpoint of suppressing exhaust emission, there is a possibility that the fuel consumption deterioration region may be expanded.

  Therefore, in this third embodiment, control based on the estimated catalyst temperature is performed instead of control based on the cooling water temperature, and as described later, the F / C return engine speed is decreased as the catalyst temperature decreases, and the fuel is reduced. The fuel cut conditions are expanded in the direction where the cut control is easy to enter.

  Hereinafter, this control will be specifically described with reference to FIG. Here, FIG. 6 is a flowchart showing a control method according to Embodiment 3 of the present invention. First, it is determined whether or not the vehicle is decelerating (step S30). If the vehicle is not decelerating (No at Step S30), the fuel cut control is not performed and the control is not performed.

  If the vehicle is decelerating (Yes at step S30), for example, the F / C return engine speed based on the conventional cooling water temperature is calculated by using the map shown in FIG. 7 (step S31).

  Next, as shown in FIG. 8, in order to set the F / C return engine speed lower as the estimated catalyst temperature is lower, the correction coefficient (F / C) multiplied by the F / C return engine speed calculated in step S31 is set. C return engine rotation correction coefficient) is calculated (step S32).

  Here, FIG. 8 is a map showing the relationship between the estimated catalyst temperature and the F / C return engine rotation correction coefficient. Experiments are performed in advance so that the F / C return engine speed can be set lower as the estimated catalyst temperature is lower. Etc.

  The active (catalyst warm-up) state of the catalyst 25 is taken into consideration by multiplying the F / C return engine rotation correction coefficient calculated in step S32 by the F / C return engine speed calculated in step S31. The final F / C return engine speed is calculated (step S33).

  Next, it is determined whether or not the current engine speed NE is greater than the final F / C return engine speed (step S34). If the current engine speed NE is greater than the final F / C return engine speed (Yes at Step S34), a fuel cut (hereinafter abbreviated as F / C in the figure) is performed (Step S34). If not large (No at step S34), the routine leaves the routine without performing the fuel cut.

  Therefore, by performing the control based on the estimated catalyst temperature in this way, the lower the catalyst temperature, the lower the F / C return engine speed, and the fuel cut conditions can be expanded in a direction in which fuel cut control can easily be entered. In addition to suppressing deterioration in fuel consumption, the catalyst 25 is leaned to suppress emission deterioration and exhaust odor.

  Conventionally, when fuel is injected from the fuel injection valve 11, the basic fuel injection time is obtained from the engine load (intake pipe pressure or intake air amount) and the engine speed. Further, the fuel injection time is obtained by correcting the basic fuel injection time with various correction coefficients determined by the intake air temperature, the coolant temperature, and the like. And according to this fuel injection time, the fuel injection valve 11 is opened and fuel injection is performed.

  In the fuel cut performed during deceleration, the engine speed is higher than a predetermined value, and after the fuel injection time falls below a predetermined injection stop determination value, the fuel cut delay time (hereinafter, “ It is abbreviated as “F / C delay time.”) If the operation is continued, it is implemented. Thereafter, when the fuel injection time exceeds a predetermined injection restart determination value, fuel injection is restarted.

  Such a conventional F / C delay time has been calculated based on the cooling water temperature as shown in the map of FIG. Here, FIG. 10 is a map showing the characteristics of the F / C delay time based on the conventional cooling water temperature.

  However, in the control based on the conventional cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. For this reason, in the control based on the coolant temperature, in order to reliably determine the active (catalyst warm-up) state of the catalyst 25 in any running state, the fuel cut control is difficult to enter, that is, the F / Since it is necessary to set the C delay time to be longer, there is a possibility that the fuel consumption deterioration area may be expanded.

  Therefore, in the fourth embodiment, the control based on the estimated catalyst temperature is performed instead of the control based on the cooling water temperature. As described later, the F / C delay time is shortened as the catalyst temperature is lower, and the fuel cut is performed. The fuel cut condition has been expanded in a direction that allows easy control.

  Hereinafter, this control will be specifically described with reference to FIG. Here, FIG. 9 is a flowchart showing a control method according to Embodiment 4 of the present invention. First, it is determined whether or not the vehicle is decelerating (step S30). If the vehicle is not decelerating (No at Step S30), the fuel cut control is not performed and the control is not performed.

  If the vehicle is decelerating (Yes at step S30), for example, the F / C delay time based on the conventional cooling water temperature is calculated by using the map of FIG. 10 described above (step S41).

  Next, in order to set the F / C delay time to be shorter as the estimated catalyst temperature is lower, a correction coefficient (F / C delay coefficient) to be multiplied by the F / C delay time calculated in step S41 is set, for example, in the map of FIG. (Step S42).

  Here, FIG. 11 is a map showing the relationship between the estimated catalyst temperature and the F / C delay time. The map is obtained in advance by experiments or the like so that the F / C delay time can be set shorter as the estimated catalyst temperature is lower. It is.

  Then, by multiplying the F / C delay coefficient calculated in step S41 by the F / C delay time calculated in step S41, the final F / C delay considering the active (catalyst warm-up) state of the catalyst 25 is taken. Time is calculated (step S43).

  Next, it is determined whether or not the current deceleration time is longer than the final F / C delay time (step S44). If the current deceleration time is longer than the final F / C delay time (Yes at Step S44), the fuel cut is performed (Step S45). If not longer (No at Step S44), the fuel cut is not performed. Leave this routine.

  Therefore, by performing control based on the estimated catalyst temperature in this way, the F / C delay time can be shortened as the catalyst temperature is lower, and the fuel cut condition can be expanded in a direction in which fuel cut control can easily be entered. While deterioration of fuel consumption can be suppressed, the catalyst 25 is made lean, and emission deterioration and exhaust odor can be suppressed.

  As described above, in the internal combustion engine 1, the fuel cut during deceleration for stopping the fuel supply when the vehicle is decelerated is executed for the purpose of improving the fuel consumption performance. The internal combustion engine 1 also includes a so-called throttle opener (not shown) configured to forcibly open and hold the throttle valve 10, and throttle opener control for opening the throttle valve 10 under predetermined conditions is performed. It has been implemented. The throttle opener amount in the throttle opener control is conventionally calculated based on the coolant temperature.

  However, in the control based on the conventional cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. Therefore, as the temperature of the catalyst 25 after the cold start of the internal combustion engine 1 is lower, the throttle opener amount is increased to promote catalyst warm-up, while after the catalyst 25 is warmed up, the throttle opener amount is decreased to reduce fuel consumption. Despite the need to control exacerbations, these were not enough. Moreover, it was not sufficient from the viewpoint of emission deterioration and exhaust odor control.

  Therefore, in the fifth embodiment, the throttle opener control based on the estimated catalyst temperature is performed instead of the control based on the cooling water temperature. Hereinafter, this control will be specifically described with reference to FIG. Here, FIG. 12 is a flowchart showing a control method according to Embodiment 5 of the present invention.

  First, it is determined whether or not fuel is being cut during deceleration (step S50). If the fuel is being decelerated during deceleration (No at Step S50), the routine is left because it is outside the scope of this control.

  If the fuel is not being decelerated during deceleration (Yes at Step S50), the throttle opener amount based on the estimated catalyst temperature is calculated using, for example, the map of FIG. 13 (Step S51). Here, FIG. 13 is a map showing the relationship between the estimated catalyst temperature and the throttle opener amount. The lower the estimated catalyst temperature, the larger the throttle opener amount can be set, and the higher the estimated catalyst temperature, the smaller the throttle opener amount can be set. As described above, it is obtained in advance by experiments or the like.

  Then, the throttle opener is controlled so as to be the throttle opener amount calculated in step S51 (step S53). Therefore, after the cold start, as the catalyst temperature is lower, the throttle opener control is strengthened, so that the catalyst 25 is leaned and emission deterioration and exhaust odor can be suppressed. Further, after the catalyst 25 is warmed up, the deterioration of fuel consumption can be suppressed by reducing the throttle opener amount.

  In the fifth embodiment, the throttle opener control is strengthened during the warm-up of the catalyst 25. However, there is a possibility that the feeling of deceleration during the warm-up deteriorates. Therefore, in this sixth embodiment, in order to suppress the deterioration of the feeling of deceleration, in addition to the control of the fifth embodiment, the ignition timing at the time of deceleration is retarded (torque down) according to the throttle opener amount.

  That is, as shown in FIG. 14, in the control of the fifth embodiment (see FIG. 12), step 52 for calculating the retard amount according to the throttle opener amount (see FIG. 15) and the ignition timing by the retard amount. And step S54 for delaying. Here, FIG. 14 is a flowchart showing a control method according to Embodiment 6 of the present invention, and FIG. 15 is a map showing the relationship between the throttle opener amount and the retard amount.

  In step S52, for example, using the map shown in FIG. 15, the retard amount is calculated so as to increase as the throttle opener amount increases. In step S54, the ignition timing is retarded by the retard amount. Can be prevented.

  Conventionally, when the internal combustion engine 1 is cold started, the fuel vaporization state is poor. Therefore, the intake air amount is increased so that the idling speed at that time is relatively high, and the startability is ensured. Idle speed control (ISCV control) is performed.

  In this technique, in order to increase the intake air amount, a bypass passage (not shown) that bypasses the throttle valve 10 and communicates the upstream side and the downstream side of the intake passage 8 is provided. An idle speed control valve (ISCV) is provided.

  When the throttle valve 10 is fully closed, ISC control is performed based on the coolant temperature, vehicle speed, and the like. As described above, the control amount (ISCV amount) of the idle speed control valve is conventionally calculated mainly based on the cooling water temperature.

  However, in the control based on the conventional cooling water temperature, the active (catalyst warm-up) state of the catalyst 25 is not directly determined. Therefore, the lower the temperature of the catalyst 25 after the cold start of the internal combustion engine 1, the more the ISCV amount is increased and the catalyst warm-up is promoted. On the other hand, after the catalyst 25 is warmed up, the ISCV amount is decreased to reduce the fuel consumption. Despite the need for suppression, these were not enough. Moreover, it was not sufficient from the viewpoint of emission deterioration and exhaust odor control.

  Therefore, in the seventh embodiment, ISCV control based on the estimated catalyst temperature is performed instead of the control based on the cooling water temperature. Hereinafter, this control will be described with reference to FIG. Here, FIG. 16 is a flowchart showing a control method according to Embodiment 7 of the present invention.

  First, it is determined whether or not fuel is being cut during deceleration (step S50). If the fuel is being decelerated during deceleration (No at Step S50), the routine is left because it is outside the scope of this control.

  If the fuel cut during deceleration is not in progress (Yes at Step S50), the ISCV amount based on the estimated catalyst temperature is calculated, for example, using the map of FIG. 17 (Step S55). Here, FIG. 17 is a map showing the relationship between the estimated catalyst temperature and the ISCV amount. The lower the estimated catalyst temperature, the larger the ISCV amount can be set, and the higher the estimated catalyst temperature, the smaller the ISCV amount can be set. This is obtained in advance by experiments or the like.

  Then, the idle speed control valve is controlled such that the ISCV amount calculated in step S55 is obtained (step S56).

  Therefore, after the cold start, the idling is strengthened as the catalyst temperature is lower, so that the fuel is prevented from adhering to the wall surface of the intake manifold 6 and the emission deterioration and the exhaust odor can be suppressed. Further, after the catalyst 25 is warmed up, the deterioration of fuel consumption can be suppressed by reducing the amount of ISCV.

  At the time of a light load immediately after the cold start of the internal combustion engine 1, since the temperature of the catalyst 25 is low, the catalyst 25 is warmed up in a rich atmosphere, and thus control for temporarily increasing the fuel injection amount (light load increase control) has been conventionally performed. Has been done more.

  Also in this case, since the warm-up state of the catalyst 25 is determined based on the cooling water temperature, it is estimated to be lower than the actual catalyst temperature, and this light load increase may be excessive (see FIG. 19). There is. As a result, an excessive catalyst-rich state is generated, and the emission and exhaust odor may be deteriorated.

  Therefore, in the eighth embodiment, the light load increase control based on the estimated catalyst temperature described above is performed instead of the control based on the cooling water temperature. Hereinafter, this control will be described with reference to FIG. Here, FIG. 18 is a flowchart showing a control method according to Embodiment 8 of the present invention.

  First, it is determined whether or not fuel is being cut during deceleration (step S50). If the fuel is being decelerated during deceleration (No at Step S50), the routine is left because it is outside the scope of this control.

  If the fuel cut during deceleration is not in progress (Yes at Step S50), the light load increase rate based on the estimated catalyst temperature is calculated, for example, using the map of FIG. 19 (Step S57). Here, FIG. 19 is a map showing the relationship between the estimated catalyst temperature and the light load increase rate. In this case, the light load increase rate is set to be lower overall than in the conventional case, and the light load increase rate is set lower (decrease setting) than the conventional case as the estimated catalyst temperature is lower. .

  Then, light load increase control is performed based on the light load increase ratio calculated in step S57 (step S58).

  Therefore, after the cold start, the lower the estimated catalyst temperature, the lower the light load increase ratio than before, and the light load increase control is performed, thereby suppressing the catalyst rich state and suppressing the emission deterioration and the exhaust odor. And deterioration of fuel consumption can be suppressed.

  When the temperature of the catalyst 25 is low, the temperature of the catalyst 25 is low even if it misfires. Therefore, there is a situation in which oxygen and unburned gas react rapidly in the catalyst 25 and the catalyst 25 melts and deteriorates due to the reaction heat. Avoided. This also leads to early warm-up of the catalyst 25.

  Since the catalyst 25 is in an excess oxygen state after the fuel cut, NOx increases. Therefore, in order to reduce this NOx, the injected fuel amount (F / C return rich amount) is gradually increased from a predetermined initial value at a predetermined ratio when the fuel cut is released and the fuel supply is started. Control to increase the amount (F / C return rich control) has been conventionally performed.

  Also in this case, since the warm-up state of the catalyst 25 is determined based on the cooling water temperature, the F 25 is estimated to be lower than the actual catalyst temperature. There is a possibility that the / C return rich amount is excessively supplied (see FIG. 21). As a result, an excessive catalyst-rich state is generated, and the emission and exhaust odor may be deteriorated.

  Therefore, in the ninth embodiment, the F / C return rich control based on the estimated catalyst temperature described above is performed instead of the control based on the cooling water temperature. Hereinafter, this control will be described with reference to FIG. Here, FIG. 20 is a flowchart showing a control method according to Embodiment 9 of the present invention.

  First, it is determined whether or not a condition for shifting to F / C return rich control is satisfied (step S60). If the condition is not satisfied (No at Step S60), the present control is excluded and the process leaves the routine.

  If the condition is satisfied (Yes at Step S60), the F / C return rich amount based on the estimated catalyst temperature is calculated by using, for example, the map of FIG. 21 (Step S61). Here, FIG. 21 is a map showing the relationship between the estimated catalyst temperature and the F / C return rich amount.

  In this case, the F / C return rich amount is set to be lower overall than in the conventional case, and the F / C return rich amount is set lower than in the conventional case as the estimated catalyst temperature is lower (decrease setting). )

  Then, F / C return rich control is performed based on the F / C return rich amount calculated in step S61 (step S70).

  Therefore, after the cold start, as the estimated catalyst temperature is lower, the F / C return rich amount is reduced than before and the F / C return rich control is performed, so that the catalyst rich state is suppressed, the emission deterioration and the exhaust odor are reduced. And the deterioration of fuel consumption can be suppressed.

  In the control of the ninth embodiment, the catalyst warm-up is delayed as the deterioration of the catalyst 25 increases. Therefore, in the tenth embodiment, in addition to the control in the ninth embodiment, correction based on the degree of deterioration (C_MAX) is performed (see steps S62 and 63 in FIG. 22 described later) to suppress emission deterioration and exhaust odor. In addition, the deterioration of fuel consumption is suppressed.

  Hereinafter, this control will be described with reference to FIG. Here, FIG. 22 is a flowchart showing a control method according to Embodiment 10 of the present invention. In FIG. 22, steps other than step S62 and step S63 are the same as in the case of the ninth embodiment, and a duplicate description is omitted.

  When the F / C return rich amount is calculated in step S61, a catalyst deterioration coefficient for correcting the F / C return rich amount according to the deterioration degree (C_MAX) of the catalyst 25 is calculated using, for example, the map of FIG. Step S62).

  The determination of the degree of deterioration is based on known means, and detailed description thereof is omitted. Here, FIG. 23 is a map showing the relationship between the catalyst deterioration degree (C_MAX) and the catalyst deterioration coefficient.

  That is, the catalyst deterioration coefficient is increased as the degree of deterioration (C_MAX) of the catalyst 25 is larger, and correction is performed so that the F / C return rich amount (final rich amount) is larger than when the degree of deterioration is small (step S63).

  Then, F / C return rich control is performed based on the final rich amount calculated in step S63 (step S70).

  Therefore, as the degree of deterioration (C_MAX) of the catalyst 25 is larger, the F / C return rich amount is corrected to be increased. Therefore, even if the catalyst 25 is largely deteriorated, warm-up can be performed early.

  In the tenth embodiment, the correction based on the deterioration degree (C_MAX) has been described. However, in the first to eighth embodiments, the correction based on the deterioration degree (C_MAX) may be performed. Further effects can be expected in each embodiment.

  Moreover, although each said Example was demonstrated as each independent control, you may implement combining these suitably.

  As described above, the control device for a vehicle according to the present invention is useful for a vehicle including an internal combustion engine with a catalyst device, and particularly aims at suppressing emission deterioration, exhaust odor, and fuel consumption deterioration during the catalyst warm-up process. Suitable for vehicles equipped with an internal combustion engine.

1 is a schematic diagram illustrating a vehicle control apparatus according to Embodiment 1 of the present invention. It is a flowchart which shows a control method. It is a map which shows the shift position upper limit guard based on estimated catalyst temperature. It is a flowchart which shows the control method which concerns on Example 2 of this invention. It is a map which shows the lockup characteristic based on estimated catalyst temperature. It is a flowchart which shows the control method which concerns on Example 3 of this invention. It is a map which shows the characteristic of the F / C return engine speed based on the conventional cooling water temperature. It is a map which shows the relationship between estimated catalyst temperature and F / C return engine rotation correction coefficient. It is a flowchart which shows the control method which concerns on Example 4 of this invention. It is a map which shows the characteristic of the F / C delay time based on the conventional cooling water temperature. It is a map which shows the relationship between estimated catalyst temperature and F / C delay time. It is a flowchart which shows the control method which concerns on Example 5 of this invention. 3 is a map showing a relationship between an estimated catalyst temperature and a throttle opener amount. It is a flowchart which shows the control method which concerns on Example 6 of this invention. 6 is a map showing a relationship between a throttle opener amount and a retard amount. It is a flowchart which shows the control method which concerns on Example 7 of this invention. It is a map which shows the relationship between estimated catalyst temperature and the amount of ISCV. It is a flowchart which shows the control method which concerns on Example 8 of this invention. It is a map which shows the relationship between estimated catalyst temperature and a light load increase rate. It is a flowchart which shows the control method which concerns on Example 9 of this invention. It is a map which shows the relationship between estimated catalyst temperature and F / C return rich amount. It is a flowchart which shows the control method which concerns on Example 10 of this invention. It is a map which shows the relationship between a catalyst degradation degree (C_MAX) and a catalyst degradation coefficient.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 11 Fuel injection valve 14 Cooling water temperature sensor 23 Exhaust passage 25 Catalyst 30 Control circuit (catalyst temperature estimation means, vehicle control device)
38 Ignition circuit

Claims (11)

In a vehicle control device including a control device that controls a vehicle including an internal combustion engine having an exhaust purification catalyst according to a warm-up state of the catalyst,
Provided with a catalyst temperature estimating means for estimating a catalyst temperature at the time of starting the engine based on at least the temperature of the engine coolant at the time of starting the engine;
The control apparatus for a vehicle according to claim 1, wherein the control in the warm-up process of the catalyst is performed based on an estimated catalyst temperature by the catalyst temperature estimating means. The vehicle includes an automatic transmission having a plurality of speed stages,
The vehicle control device according to claim 1, wherein the control limits the shift-up of the automatic transmission as the estimated catalyst temperature is lower. The vehicle includes an automatic transmission having a torque converter with a lock-up mechanism,
The vehicle control device according to claim 1, wherein the control prohibits lock-up as the estimated catalyst temperature is lower. The internal combustion engine is subjected to fuel cut control in which fuel supply is stopped under predetermined conditions,
2. The vehicle control device according to claim 1, wherein the control decreases the engine speed when returning from the fuel cut control and restarting the fuel supply as the estimated catalyst temperature is lower. 3. The internal combustion engine is subjected to fuel cut control in which fuel supply is stopped under predetermined conditions,
2. The vehicle control device according to claim 1, wherein the control shortens a fuel cut delay time, which is a threshold for performing the fuel cut control, as the estimated catalyst temperature is lower. 3. The internal combustion engine is subjected to throttle opener control for opening a throttle valve under predetermined conditions,
The vehicle control device according to claim 1, wherein the control increases the throttle opener amount as the estimated catalyst temperature is lower.   The vehicle control device according to claim 6, wherein the ignition timing is retarded as the throttle opener amount increases. The internal combustion engine performs idle speed control by adjusting a control amount of an idle speed control valve under predetermined conditions.
The vehicle control device according to claim 1, wherein the control increases the control amount of the idle speed control valve as the estimated catalyst temperature is lower. The internal combustion engine is subjected to light load increase control for increasing the fuel injection amount at a light load immediately after a cold start,
The vehicle control device according to claim 1, wherein the control decreases the increase rate as the estimated catalyst temperature is lower. The internal combustion engine is subjected to fuel cut control in which fuel supply is stopped or restarted under predetermined conditions, and the fuel injection amount is controlled to increase when the fuel cut is released and the fuel supply is started. ,
2. The vehicle control device according to claim 1, wherein the control decreases the amount of the increase control as the estimated catalyst temperature is lower. The internal combustion engine includes a deterioration degree determination unit that determines a deterioration degree of the catalyst.
The vehicle control device according to claim 10, wherein the amount of increase control is increased and corrected as the degree of deterioration by the deterioration degree determination unit increases.

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