JPH0771304A - Controller of internal combustion engine - Google Patents

Abstract

PURPOSE:To start accurate air fuel ratio feedback control for warming-up condition by estimating the temperature condition of an internal combustion engine from the integrated value of the temperature of cooling water at the time of starting and the value corresponding to the quantity of inlet air from starting time, and by thus controlling the temperature of the engine. CONSTITUTION:When an engine is not yet started at a step 100, water temperature is read at a step 101 and the integrated value of the quantity of inlet air for judging feedback starting is determined from a map at a step 102 and is set. After the engine is started, it is judged at a step 103 whether it is during fuel cut or not, and when during cut, the routine is finished at a step 107 to hold the value before cut. When it is not during cut, the quantity of inlet air is integrated at a step 104, and the integrated value is compared with the integrated value of the quantity of air for judging feedback starting before engine start, and when the former is larger, it is judged as after warming-up, and feedback control is started at a step 106, and when the latter is larger, feedback control is not carried out at a step 108. The cost can be reduced while degradation of fuel consumption and emission can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an internal combustion engine which measures the engine temperature after the start of the engine, and more specifically, a cooling water temperature measuring means for measuring the temperature of the cooling water at the time of starting, and The present invention relates to a control device for an internal combustion engine, which includes a calculation unit that calculates an integrated value of intake air amount equivalent values.

[0002]

2. Description of the Related Art Japanese Utility Model Laid-Open No. 63-26748 discloses an internal combustion engine in which secondary air is supplied to an exhaust system to accelerate warm-up of a catalyst and, after warm-up, air-fuel ratio feedback control is performed. When the catalyst is sufficiently warmed up, the supply of secondary air is stopped, feedback control of the air-fuel ratio is performed, and for the purpose of preventing overheating of the catalyst and deterioration of emissions due to delay in starting feedback control, An air-fuel ratio sensor is provided in the exhaust system, and feedback control of the air-fuel ratio is performed based on the output from this sensor.On the other hand, the temperature of the catalyst is detected and it is determined whether the catalyst has reached a warm-up state, When the engine is warming up, the supply of secondary air is stopped and the air-fuel ratio feedback control is started. In this case, the temperature of the internal combustion engine is estimated from the integrated intake air amount from the start.

[0003]

By the way, the cooling water temperature,
That is, the temperature of the engine changes according to the state of the internal combustion engine at the time of starting, but in the above-mentioned conventional technology, since the state at the time of starting is not taken into consideration, the integrated intake air for determining the start of the feedback control of the air-fuel ratio. Since the predetermined value of the amount is fixed, it is determined that the internal combustion engine is not warmed up even if it is actually warmed up, and there is a problem that the feedback is not started and the emission is deteriorated.

Therefore, according to the present invention, the timing at which the feedback control of the air-fuel ratio is started, that is, the warm-up state of the engine is made variable by the engine water temperature at the time of starting the engine, so that the warm-up state of the internal combustion engine can be improved. An object is to start accurate air-fuel ratio feedback control.

[0005]

In order to achieve the above object, according to the invention of claim 1, in a control device for an internal combustion engine for measuring the temperature of an internal combustion engine after starting, cooling water at the time of starting The cooling water temperature measuring means for measuring the temperature of the internal combustion engine, the calculating means for calculating the integrated value of the intake air amount equivalent value from the start, and the temperature state of the internal combustion engine from the cooling water temperature and the integrated value of the intake air amount equivalent value. There is provided a control device for an internal combustion engine, comprising:

According to the second aspect of the present invention, in a control device for an internal combustion engine for measuring the temperature of an internal combustion engine after starting, cooling water temperature measuring means for measuring the temperature of cooling water at starting, The internal combustion engine is provided with a calculating means for calculating an integrated value of the intake air amount equivalent value, and a calculating means for calculating a start timing of feedback control of the air-fuel ratio of the internal combustion engine from the cooling water temperature and the integrated value of the intake air amount equivalent value. An engine controller is provided.

According to a third aspect of the present invention, in a control device for an internal combustion engine equipped with an electrically heating type catalyst for electrically heating a catalyst provided in an exhaust system of an internal combustion engine, the temperature of cooling water at start-up. The energization of the energization heating type catalyst is completed from the cooling water temperature measuring means for measuring the above, the calculating means for calculating the integrated value of the intake air amount equivalent value from the start, and the integrated value of the cooling water temperature and the intake air amount equivalent value. Provided is a control device for an internal combustion engine, which comprises a calculating means for calculating a time.

According to a fourth aspect of the invention, in addition to the cooling water temperature and the integrated value of the intake air amount equivalent value, the energization end timing of the energization heating type catalyst is calculated from the voltage state of the battery. A control device for an internal combustion engine according to claim 3 is provided. According to the invention of claim 5, in an internal combustion engine control device for measuring the temperature of an internal combustion engine after starting, cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting, and an intake air amount from the time of starting. Provided is a control device for an internal combustion engine, comprising: a calculating unit that calculates an integrated value of equivalent values; and a calculating unit that calculates a fuel increase coefficient during warming up from the cooling water temperature and the integrated value of the intake air amount equivalent values. It

According to the sixth aspect of the present invention, in a control device for an internal combustion engine, comprising an exhaust gas recirculation device for recirculating a part of exhaust gas from an exhaust system to an intake system, the temperature of cooling water at the time of starting A cooling water temperature measuring means for measuring the above, a calculating means for calculating an integrated value of the intake air amount equivalent value from the time of starting, and an exhaust gas recirculation device based on the cooling water temperature and the integrated value of the intake air amount equivalent value. There is provided a control device for an internal combustion engine, comprising: a calculation unit that calculates a start timing of exhaust gas recirculation.

[0010]

According to the invention of the present application, since the start time of the feedback control of the air-fuel ratio is changed depending on the water temperature at the time of starting the engine, the engine reaches the warmed-up state and the catalyst is started especially when the engine is started when the engine is cold. It is possible to prevent deterioration of fuel consumption and deterioration of emission that occur because the feedback control of the air-fuel ratio is not started even though the temperature reaches the activation temperature. Further, since the emission (especially CO emission) when the engine is cold can be reduced, the cold CO emission regulation can be achieved without the secondary air device, and the cost can be reduced. Furthermore, compared to the case where the feedback control is started when the engine water temperature reaches a certain value as in the past, even after the water temperature sensor becomes abnormal after the start, the integrated intake air amount or the integrated value of the load When the engine temperature exceeds the predetermined value set by the starting water temperature, feedback control of the air-fuel ratio is started, and the deterioration of emission can be prevented.

According to the third aspect of the present invention, control is performed according to the amount of heat generated by the electrically heated catalyst and the amount of heat received from the exhaust gas. Therefore, for example, when the user miswires the battery, Alternatively, it is possible to prevent the electrically heated catalyst from being overheated or burned out when an incorrect battery (for example, a 24V battery) is assembled.

According to the invention of claim 3 or 4, the integrated intake air amount (TGA) judgment value (TGAGR
Since D) is variable depending on the water temperature (THWST) when the engine is started, it is possible to perform optimum catalyst warm-up control,
It is possible to reduce variations in the temperature reached by the catalyst when the energization is stopped. According to the fifth aspect of the present invention, the warm-up fuel increase coefficient is calculated by the equivalent value of the integrated intake air amount and the cooling water temperature at the start, so it is possible to set the fuel increase value according to the actual combustion state. Becomes According to the invention described in claim 6, the start timing of the exhaust gas recirculation (EGR) control is optimally controlled according to the starting state of the engine and the degree of warm-up.

[0013]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a flowchart of the first embodiment of the present invention. In step 100, the engine starting state (XSTEFI) is determined, and the engine is not started (XSTEFI).
When I = 1), the water temperature (THW) of the engine is read in step 101, and the integrated value (KFBGAC) of the feedback start determination intake air amount set by the starting water temperature (THW) in step 102 is shown below. Obtain from the map as shown and set the value. That is, Table 1 below shows a map of the intake air amount integrated value (KFBGAC) for determining the feedback start with respect to the starting water temperature (THW), which is obtained by experiments or the like.

[0014]

[Table 1]

After starting the engine, in step 103,
Determine if the fuel is being cut (XFC),
If the fuel is being cut (XFC = 1), the routine proceeds to step 107, where the intake air amount is not integrated, and the routine is ended. As a result, the integrated value (GACi) of the intake air amount holds the value before the fuel cut (G
ACi = GACi-1). That is, since the intake air amount is not integrated during the fuel cut, only the air amount that actually contributed to the combustion is integrated, so that the estimation of the warm-up state is made more reliable.

If the fuel is not being cut, the intake air amount is integrated in step 104 (GACi =
GACi-1 + GA). Here, GA is the intake air amount (g) per unit time (1 second). In step 105, the integrated value of intake air amount (GACi) is compared with the integrated value of intake air amount for feedback start determination (KFBGAC) set at the start. When the integrated value of the intake air amount exceeds the integrated value of the intake air amount for feedback start determination (GACi ≧ KFBGAC), it is determined that the engine has been warmed up, and the feedback control of the air-fuel ratio is started in step 106. . On the other hand, if the integrated value of the intake air amount does not exceed the integrated value of the intake air amount for feedback start determination (GACi <KFBGAC), step 1
At 08, the air-fuel ratio feedback control is not started.

It should be noted that the integrated value of the intake air amount for determining the feedback start is made smaller as the starting water temperature is higher. FIG. 2 shows a flowchart of the second embodiment of the present invention. Only points different from the first embodiment will be described. In this embodiment, the feedback control of the air-fuel ratio is determined by the integrated value of the engine load, that is, the integrated value of the intake air amount per one revolution of the engine.

Before starting (XSTEFI = 1)
Reads the engine water temperature (THW) in step 101, and starts the engine water temperature (THW) in step 112.
The integrated value (KFBGNC) of the intake air amount per one revolution of the engine for feedback start determination set by is obtained from the map shown in Table 2 below, and the value is set. That is, Table 2 is a map in which the integrated value (KFBGAC) of the intake air amount per one revolution of the engine for feedback start determination with respect to the starting water temperature (THW) is obtained by experiments or the like.

[0019]

[Table 2]

When the fuel is being cut (XFC = 1) after the engine is started, in step 117, the integrated value (GNCi) of the intake air amount per one revolution of the engine holds the value before the fuel cut (GNCi). = GNCi-
1). If the fuel cut is not in progress, step 11
4, the intake air amount GN (g / r
ev) is integrated (GNCi = GNCi-1 + GN).
Then, in step 115, the integrated value (GNCi) of the intake air amount per one revolution of the engine is compared with the integrated value of the intake air amount per one revolution of the engine for feedback start determination (KFBGNC) set at the time of starting. When the integrated value of intake air amount per engine revolution exceeds the integrated value of intake air amount per engine revolution for feedback start determination (G
NCi ≧ KFBGNC) determines that the engine has been warmed up, and in step 106, feedback control of the air-fuel ratio is started. On the other hand, when the integrated value of intake air amount per engine revolution does not exceed the integrated value of intake air amount per engine revolution for feedback start determination (GNCi <KFB
GNC) does not start the air-fuel ratio feedback control in step 108.

As described above, in the first or second embodiment, the start timing of the feedback control of the air-fuel ratio is changed depending on the water temperature of the engine, so that the engine is warmed up especially when the engine is started when it is cold. It is possible to prevent the deterioration of fuel consumption and the deterioration of emissions that occur because the feedback control of the air-fuel ratio is not started even though the state has been reached and the catalyst has reached the activation temperature. Further, since the emission (especially CO emission) when the engine is cold can be reduced, the CO emission regulation at the time of cold can be achieved without the secondary air supply device, resulting in cost reduction. Furthermore, compared to the case where the feedback control of the air-fuel ratio is started when the engine water temperature is equal to or higher than a certain value as in the conventional case, after the start, even when the water temperature sensor detects a predetermined temperature or higher, the accumulated intake air amount or If the integrated value of the load does not exceed the predetermined value set by the water temperature at the time of starting, there is an effect that the emission control can be prevented from being deteriorated by not starting the feedback control.

FIG. 3 shows a constitutional example in which two electric heating type catalysts are arranged in parallel. Each of the two parallel exhaust passages is provided with a respective catalyst assembly 1 and 2, and upstream thereof, further electrically heated catalysts 3 and 4 are respectively provided. By controlling the port 6 or the relay 7 of the electronic control unit (ECU) 5 of the engine, the power supply from the battery 8 and the alternator 9 to the electrically heated catalysts 3 and 4 is controlled, and the electrically heated catalysts 3 and 4 are controlled. Is energized.

FIG. 4 is a flow chart (third embodiment) for controlling the power supply to the electrically heated catalysts 3 and 4. When the base routine (BEHC) is started, first, at step 201, it is determined whether or not the precondition for executing the secondary air supply to the exhaust system is satisfied, that is, whether the flag XAIREX = 1. Is determined. The flag XAIREX is executed by a secondary air control routine (not shown), and the prerequisite for executing the secondary air supply is when the water temperature at the time of start is within a predetermined range and when the predetermined start mode is exited. It is judged to be satisfied.

When the precondition for executing such secondary air supply is satisfied (XAIREX = 1), in step 202, the predetermined value (TGAmax) of the integrated intake air amount after the start is set to the value at the start. Engine water temperature (THW)
And a battery voltage (BAT) table. FIG. 5 shows a predetermined value (TG) of the accumulated intake air amount after starting from the engine water temperature (THW) and the battery voltage (BAT) at the time of starting.
It is a map for obtaining (Amax). Further, FIG. 6 is a map for obtaining the energization time to the electrically heated catalysts 3 and 4.

The power supplied to the electrically heated catalysts 3 and 4 is substantially determined by the power supply voltage (battery voltage). That is, when the operating condition of the engine is constant, the amount of heat received from the exhaust gas is constant, and the time until the catalyst reaches the activation temperature is determined by the battery voltage. When the engine operating condition is constant (for example, the fuel injection state is left constant), the time is a predetermined value (TGAmax) of the integrated intake air amount (TGA) after the start.
Even if engine operating conditions change, such as racing or immediate start, a predetermined amount of heat received from exhaust gas can be obtained at TGAmax.

As shown in FIG. 5, TGAmax is relatively small when the battery voltage is high, and TGAmax is relatively large when the battery voltage is low. Also,
When the water temperature is high, TGAmax is made relatively small, and when the water temperature is low, TGAmax is made relatively large. When the battery voltage is 16 V or higher, the energization of the electrically heated catalyst is prohibited. This reduces the electrical load that occurs when an inadvertently high voltage is applied to the electrically heated catalyst, such as when another power source is connected in series to the electrically heated catalyst for some reason. This is for fail-safe to protect the heated catalyst.

In step 203 of FIG. 4, it is determined whether or not the integrated intake air amount (TGA) after starting exceeds a predetermined value (TGAmax), that is, whether the engine consumes a predetermined air amount. . When not consumed (TGA <
In step 204, it is determined whether or not the elapsed time (CAST1) after starting exceeds a predetermined value, for example, 10 seconds. When the value is less than a predetermined value (CAS
For T1 ≦ 10), in step 205, energization of the electrically heated catalyst is carried out (YEHC ← 1).

When the predetermined value (CAST1) of the elapsed time after the start is made variable in step 204, the energization time is obtained based on the map shown in FIG. That is, as shown in FIG. 6, when the battery voltage is high, the energization time is relatively short, and when the battery voltage is low, the energization time is relatively long. When the water temperature is high, the energization time is relatively short, and when the water temperature is low, the energization time is relatively long. When the battery voltage is 16 V or higher, the energization of the electrically heated catalyst is prohibited for the same reason as described above.

If the conditions are not satisfied in steps 201, 203, and 204, in step 206, the energization of the electrically heated catalyst is stopped (YEHC ← 0), and this routine is ended (EQ).
U). FIG. 7 is a flowchart according to another embodiment (Embodiment 4) for controlling the power supply to the electrically heated catalyst. In this embodiment, the post-start accumulated intake air amount (TGA) in the third embodiment described with reference to FIG.
GF). Therefore, only the part different from the flowchart of FIG. 4 will be described.

First, at step 201, it is judged whether or not the precondition for executing the secondary air supply to the exhaust system is satisfied, and if the precondition for the secondary air supply is satisfied (XAIREX = 1) In step 211, it is determined whether or not the energization heating type catalyst is energized, and if the energization is not performed (YEHC = 0)
In step 212, a predetermined value (TGFmax) of the integrated fuel amount after starting is obtained from a table of engine water temperature (THW) and battery voltage (BAT) at the time of starting (not shown). Predetermined value of cumulative fuel amount after starting (TGFma
x) can be obtained by a map similar to the map for obtaining the predetermined value (TGAmax) of the integrated intake air amount after the start shown in FIG.

In step 211, when the energization heating type catalyst is energized (YEHC = 1).
Moves to the next step 213 without executing the above table search in step 212. That is,
The predetermined value of the integrated intake air amount immediately before the energization of the electrically heated catalyst (that is, the value obtained from THW and BAT) is maintained.

In step 213, it is determined whether or not the integrated fuel amount (TGF) after starting exceeds a predetermined value (TGFmax), that is, whether the engine consumes a predetermined fuel amount. When not consumed (TGF <TGFma
x) proceeds to step 204 and performs the same control as in the case of FIG. When the energization control to the electrically heated catalyst is performed as in Examples 3 and 4 described in FIGS. 4 to 7, control is performed according to the heat generation amount of the electrically heated catalyst and the amount of heat received from the exhaust gas. , For example, if the user miswires the battery, or if the battery is wrong (for example, 24V)
It is possible to prevent the electrically heated catalyst from being overheated or burned out when the catalyst is assembled.

FIG. 8 is a flow chart according to yet another embodiment (fifth embodiment) for controlling the power supply to the electrically heated catalyst. In this embodiment, the cumulative intake air amount (T
The judgment value (GAGRD) of (GA) is changed according to the water temperature (THWST) at the time of engine start, the energization time to the electrically heated catalyst is made variable, and optimal catalyst warm-up control is performed to reach the catalyst when the energization is stopped. It is intended to reduce variations in temperature.

When the base routine (BEHC) is started, first, at step 301, the engine starting state (X
STEFI) is determined, and before starting (XSTEFI = 1), the water temperature (THW) of the engine is read in step 302, and the water temperature at the time of starting is THWST. After the engine is started, it is determined in step 303 whether or not the preconditions for executing the secondary air supply to the exhaust system are satisfied.
That is, it is determined whether the flag XAIREX = 1. When the prerequisites for the secondary air supply are met (XAI
In step 304, REX = 1) calculates the determination value (TGAGRD) of the integrated intake air amount (TGA) after the start, based on the engine water temperature at the start (THWST).

FIG. 9 shows the judgment value (TGAGRD) of the integrated intake air amount after the start depending on the engine water temperature at the start (THWST).
Is a map for calculating Further, FIG. 10 shows the catalyst temperature after engine startup (during low temperature startup and high temperature startup), the integrated value of the intake air amount, and the vehicle speed over time. When the water temperature at the time of start is low, the energy required to reach the activation temperature of the catalyst is large, so it is necessary to set the energization time to the electrically heated catalyst to be long (T1) as shown in FIG. . On the contrary, when the water temperature at the time of starting is high, the activation temperature of the catalyst can be reached with a small amount of energy, so the energization time to the electrically heated catalyst may be set short (T2).

In step 305, it is determined whether or not the integrated intake air amount (TGA) after starting has reached a predetermined determination value (TGAGRD), that is, whether the engine is consuming a predetermined air amount. When not consumed (TGA <T
In step 306, the GAGRD) determines whether or not the elapsed time (CAST1) after starting exceeds a predetermined value, for example, 10 seconds. When the value is less than a predetermined value (CAST1
In the case of ≦ 10), in step 307, electricity is supplied to the electrically heated catalyst (YEHC ← 1).

If the conditions are not satisfied in steps 303, 305, and 306, the energization of the electrically heated catalyst is stopped in step 308 (YEHC ← 0), and this routine is ended (EN
D). As described above, in the flowchart of FIG. 8, the determination value (TGAGRD) of the integrated intake air amount (TGA) is variable depending on the water temperature (THWST) at the time of engine start.
The optimum catalyst warm-up control can be performed, and the variation in the temperature reached by the catalyst when the energization is stopped can be reduced.

FIG. 11 is a flow chart of a routine (sixth embodiment) for obtaining the fuel increase coefficient during warm-up based on the integrated intake air amount. This routine is executed every 128 ms. First, at step 401, the operating state of the engine, for example, the engine speed (NE), the intake air amount (GA),
Detects engine cooling water temperature (THW), etc. Next step 4
In 02, the starting state of the engine is determined, and the starting state (XST
When EFI = 1), based on the engine cooling water temperature (THW), at step 406, the initial value of the fuel increase coefficient at warming up (FWLI) is set, and at step 407, the cumulative intake air amount at completion of warming up. (KTCGA) is calculated. These values are the warm-up fuel increase coefficient initial value (FWLI) and the warm-up completion intake air amount (K) for the engine cooling water temperature (THW) shown in FIGS. 12 and 13, respectively.
It is obtained from a map showing the characteristics of TCGA). In step 408, the integrated intake air amount (CGA) is cleared, and the process proceeds to step 409.

When it is determined in step 402 that the engine is in a state after starting (XSTEFI = 0), in step 403 the intake air is integrated by the following equation. CGAi = CGAi-1 + GA When overflow occurs in step 403, that is, when the integrated intake air amount (CGA) exceeds the integrated intake air amount (KTCGA) at the completion of warm-up, the value of the integrated intake air amount is changed in step 405. Guard against the value (CGA
i = ¥ FFFF), and proceeds to step 409. Step 4
If no overflow occurs in 03, the process directly proceeds to step 409.

In step 409, the warming-up fuel increase coefficient (FWL) is multiplied by the warming-up fuel increase coefficient initial value (FWLI) set at the time of start of the degree of arrival of the accumulated intake air amount until completion of warm-up, as shown in the following equation. Calculate and exit the routine. FWL = FWLI × (KTCGA-CGA) / KTCG
A At this time, KTCGA-CGA limits the minimum value to 0.

With the routine as described above, the warm-up fuel increase coefficient (F) is increased as the accumulated intake air amount (CGA) is increased.
By setting the fuel increase amount during warm-up so as to decrease WL), it is possible to set the fuel increase value according to the actual combustion state of the engine. In addition, in the routine shown in FIG.
In step 403, the intake air amount is always integrated except when the engine is started. However, similar to steps 103 and 107 in the routine of FIG. 1, it is more preferable not to integrate the intake air amount during the fuel cut. An accurate warm-up fuel increase coefficient (FWL) can be obtained. Further, since stable combustion can be obtained even when the warm-up fuel increase coefficient (FWL) = 0, that is, when the stoichiometric air-fuel ratio is reached, the warm-up fuel increase coefficient (FWL) is controlled by this routine. The air-fuel ratio feedback control may be started at the time when it becomes zero.

14 to 17 show Embodiment 7 of the present invention, in which an internal combustion engine is equipped with an exhaust gas recirculation (EGR) device for recirculating a part of exhaust gas from the exhaust system to the intake system. An example in which the disclosure timing of EGR control is calculated based on the integrated intake air amount in the apparatus will be described.

First, FIG. 14 shows an EG for performing such control.
It is the schematic which shows the whole internal combustion engine provided with the R apparatus.
In FIG. 14, 10 is an engine body, 11 is an air cleaner, 12 is an air flow meter, 13 is a throttle valve, 14 is an intake passage, 15 is a surge tank, 16 is an intake valve, 17 is an exhaust valve, 18 is an exhaust passage, 19 is EGR
A passage, 20 is an EGR valve, 21 is an EGR negative pressure adjusting valve, 22 is an EGR three-way negative pressure switching valve, 23 is an EGR control computer, and 24 is an engine cooling water temperature sensor. The intake air passes through the air cleaner 11, the air flow meter 12, the throttle valve 13, and the surge tank 15 and is drawn into the combustion chamber of the internal combustion engine from the intake valve 16. Exhaust gas is exhausted from the exhaust valve 17 through the exhaust passage 18, but a part of the exhaust gas is exhausted from the exhaust passage 18 to the EGR passage 1.
9 through the EGR valve 20 into the intake passage 14 upstream of the surge tank 15 as EGR gas.

In a typical EGR device, the EGR valve 2
0 is a diaphragm type, and negative pressure from two ports provided in the throttle body with different rising edges of negative pressure is regulated by the EGR negative pressure adjusting valve 21 to adjust the EGR.
By applying pressure to the diaphragm of the valve 20, E
The GR valve 20 is controlled to control the flow rate of EGR gas. Also, of the two ports, throttle valve 1
EGR in the negative pressure path that rises earlier with the operation of 3
A three-way negative pressure switching valve 21 is installed. The EGR three-way negative pressure switching valve 21 is opened to the atmosphere in a non-energized state and transmits a negative pressure from the port in an energized state. Therefore, when forcibly shutting off the flow of EGR gas, the EGR three-way negative pressure switching valve 21 is de-energized,
By opening the port on the EGR negative pressure adjusting valve 21 side to the atmosphere, the EGR valve 20 is closed and the flow of EGR gas to the intake side is forcibly cut off.

The control computer 23 receives signals such as engine speed (NE), intake air amount (GA), throttle valve opening (θth), engine cooling water temperature detected by the temperature sensor 24, and the like. Based on the signal, a signal is sent to the negative pressure switching valve 22 along with basic control of ignition timing, fuel injection amount, etc. according to the engine operating state, and EGR is performed.
Controls gas ON / OFF. The time when the EGR gas control is started when the wall temperature of the combustion chamber exceeds a certain temperature, and the estimated value of the combustion chamber wall temperature is the engine cooling water temperature detected by the engine cooling water temperature sensor 24 and the intake air amount. It is calculated from the integrated value of equivalent values. That is, the combustion chamber wall temperature is
It is considered that the engine cooling water temperature at the time of starting is used as an initial value, and the amount of temperature increase depends on the inflowing heat generation amount, that is, the integrated value of the intake air amount.

Therefore, in this embodiment, as shown in FIG. 15, as an example, the cumulative intake air amount until combustion is stabilized by the water temperature at the time of starting is used as a map, and at the time of starting, E
The GR control start cumulative intake air amount is calculated. That is, in FIG. 15, the horizontal axis represents the water temperature at the time of starting, and the vertical axis represents EG.
The R control start integrated intake air amount is shown.

FIG. 16 is a flow chart of a routine (embodiment 7) for controlling the EGR valve 20 by the integrated intake air amount. First, in step 501, the operating state of the engine, for example, the engine speed (NE), the intake air amount (G
A), throttle valve opening (θth), etc. are detected.
Next, in step 502, the engine start state is determined,
When in the starting state (XSTEFI = 1),
In step 505, the counter of the integrated intake air amount CGA is cleared, and in step 506, the EGR control start integrated intake air amount (KCGAEGR) is calculated based on the cooling water temperature at the start according to the map shown in FIG.
7, EGR control negative pressure switching valve (EGRVSV) 2
Turn OFF 2 and exit the routine.

When the engine is not started in step 502, in step 503, the accumulated intake air amount (C
GA) and EGR control start integrated intake air amount (KCGAEG
R) is compared, and if CGA is smaller, it is determined that the combustion is not yet stable, and in step 507, the EGR control negative pressure switching valve (EGRVSV) is turned off and the routine exits. If the integrated intake air amount (CGA) is equal to or larger than the EGR control start integrated intake air amount (KCGAEGR) in step 503, EG
It is determined that the combustion is sufficiently stabilized even if the R gas is supplied to the intake system, the negative pressure switching valve for EGR control (EGRVSV) is turned on in step 504, and the EGR valve 20 (FIG. 14) is opened to perform the EGR control. Start.

Further, in this embodiment, as shown in FIG. 17, the intake air amount (GA) is integrated every 128 ms, and the maximum (MAX) value is guarded so as not to overflow. That is, in FIG. 17, when the integrated intake air amount (CGA) has not reached the MAX value in step 601, the intake air amount (G
A) is integrated, and when the MAX value is reached in step 601, the integrated intake air amount at that time, that is, KCGAEGR
Hold.

As described above, according to the seventh embodiment, the start timing of the EGR control can be optimized in accordance with the engine starting state and the warm-up process, so that the exhaust characteristics can be improved especially at low temperature starting (especially, Nox emissions can be reduced). In the embodiment shown in FIG. 14, the negative pressure control type EGR valve 2 is used.
Although 0 is used, the same effect can be obtained when an EGR valve of another system is used. Further, although the EGR control start integrated intake air amount (KCGAEGR) is a one-dimensional map based on the starting water temperature as shown in FIG. 15 in the above control, a higher load than a rolling load or a higher rotation than a low rotation is better. Since combustion fluctuations are less likely to occur, it is possible to create a map that has been corrected by the load and rotation speed.

Although the embodiments have been described in detail with reference to the accompanying drawings of the present invention, the present invention is not limited to the above embodiments, and various embodiments within the spirit and scope of the present invention, It should be noted that variations, modifications, etc. are possible.

[0052]

According to the invention of the present application, since the start time of the air-fuel ratio feedback control is changed depending on the water temperature at the time of starting the engine, it is possible to prevent deterioration of fuel consumption and emission at low cost. According to the third aspect of the present invention, control is performed according to the amount of heat generated by the electrically heated catalyst and the amount of heat received from the exhaust gas. Therefore, the electrically heated catalyst is prevented from being excessively heated or burned out. It can be effectively prevented.

According to the third or fourth aspect of the invention, the judgment value (TGAGR) of the cumulative intake air amount (TGA) is
Since D) is variable depending on the water temperature (THWST) at the engine start, the temperature reached by the catalyst can be kept constant when the energization is stopped. According to the invention of claim 5,
Since the equivalent value of the cumulative intake air amount (CGA) and the cooling water temperature at the start set the warm-up fuel increase coefficient (FWL),
The fuel increase value can be set according to the actual combustion state of the engine, and the fuel consumption and warm-up characteristics can be improved.

According to the sixth aspect of the present invention, the start timing of the exhaust gas recirculation (EGR) control can be optimally controlled according to the starting state of the engine and the warm-up process. It is possible to improve the characteristics (in particular, reduce Nox).

[Brief description of drawings]

FIG. 1 is a flowchart according to a first embodiment of the present invention.

FIG. 2 is a flowchart similar to FIG. 1 according to a second embodiment of the present invention.

FIG. 3 shows a configuration example in which two electric heating type catalysts are arranged in parallel.

FIG. 4 is a flow chart (Example 3) for controlling the power supply to the electrically heated catalyst.

FIG. 5 is a diagram showing a predetermined value (T) of an integrated intake air amount after starting from a water temperature (THW) and a battery voltage (BAT) of the engine at the time of starting.
This is a map for obtaining (GAmax).

FIG. 6 is a map for obtaining an energization time to an electrically heated catalyst from a water temperature (THW) and a battery voltage (BAT) of the engine at the time of starting.

FIG. 7 is a flowchart according to a fourth embodiment of the present invention.

FIG. 8 is a flowchart according to still another embodiment (Example 5) for controlling the power supply to the electrically heated catalyst.

FIG. 9 is a map for calculating a determination value (TGAGRD) of the integrated intake air amount after the start, based on the engine water temperature at the start (THWST).

FIG. 10 is a diagram showing a change in catalyst temperature, a change in integrated intake air amount, and a change in vehicle speed depending on temperature conditions at the time of engine start.

FIG. 11 is a flowchart of a routine (embodiment 6) for obtaining a fuel increase coefficient during warm-up based on an integrated intake air amount.

FIG. 12 is a map showing the characteristics of the initial value (FWLI) of the fuel increase coefficient during warm-up with respect to the engine cooling water temperature (THW).

FIG. 13 is a map showing a characteristic of an integrated intake air amount (KTCGA) at the time of completion of warming up with respect to an engine cooling water temperature (THW).

FIG. 14 is a schematic diagram of an internal combustion engine including an EGR device that implements a seventh embodiment.

FIG. 15 is a map for obtaining an EGR control start integrated intake air amount from the water temperature at the time of starting.

FIG. 16 is a flowchart of a routine (Embodiment 7) for controlling the EGR valve by the integrated intake air amount.

FIG. 17 is a flowchart for guarding the accumulated intake air amount to the MAX value.

[Explanation of symbols]

 1, 2 ... Catalyst assembly 3, 4 ... Electric heating type catalyst 5 ... Electronic control unit (ECU) 7 ... Relay 8 ... Battery 9 ... Alternator

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 25/07 550 H (72) Inventor Hidemi Onaka 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Corporation Stock In-house (72) Inventor Hiroshi Tanaka 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd. (72) Inventor Kenichi Harada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (6)

[Claims] 1. A control device for an internal combustion engine for measuring the temperature of an internal combustion engine after starting, wherein a cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting, and an integrated value of intake air amount equivalent values from the time of starting A control device for an internal combustion engine, comprising: a calculating means for calculating the temperature of the internal combustion engine; 2. A control device for an internal combustion engine, which measures the temperature of an internal combustion engine after starting, comprising: cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting; and an integrated value of intake air amount equivalent values from the time of starting. A control device for an internal combustion engine, comprising: a calculating means for calculating the above; and a calculating means for calculating a start timing of feedback control of an air-fuel ratio of the internal combustion engine from the cooling water temperature and the integrated value of the intake air amount equivalent value. 3. A cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting, in a control device for an internal combustion engine equipped with an electrically heating type catalyst for electrically heating a catalyst provided in an exhaust system of an internal combustion engine. A calculation means for calculating an integrated value of the intake air amount equivalent value from the start, and a calculation means for calculating an energization end timing of the electrically heated catalyst from the cooling water temperature and the integrated value of the intake air amount equivalent value. A control device for an internal combustion engine provided. 4. The internal combustion engine according to claim 3, wherein the energization end timing of the electrically heated catalyst is calculated from the voltage state of the battery in addition to the cooling water temperature and the integrated value of the intake air amount equivalent value. Control device. 5. A control device for an internal combustion engine, which measures the temperature of an internal combustion engine after starting, comprising: cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting; and an integrated value of intake air amount equivalent values from the time of starting. A control device for an internal combustion engine, comprising: a calculating means for calculating the above; and a means for calculating a fuel increase coefficient during warm-up from the integrated value of the cooling water temperature and the intake air amount equivalent value. 6. A cooling water temperature measuring means for measuring the temperature of cooling water at the time of starting, in a control device for an internal combustion engine comprising an exhaust gas recirculation device for recirculating a part of exhaust gas from an exhaust system to an intake system. A start time of exhaust gas recirculation by the exhaust gas recirculation device based on the calculation means for calculating the integrated value of the intake air amount equivalent value from the start-up time, and the cooling water temperature and the integrated value of the intake air amount equivalent value. A control device for an internal combustion engine, comprising: calculating means for calculating.