JP2006348930A - Intake pipe negative pressure correlation value predicting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To always accurately predict an intake pipe negative pressure correlation value irrespective of the warmup state of an internal combustion engine in an intake pipe negative pressure correlation value predicting system. <P>SOLUTION: An intake air temperature tha, an intake air amount Ga, and an engine speed NE are taken in this system (S100). The maximum intake air amount (reference G/N/wot) per rotation which can be realized when both the intake air temperature tha and a cooling water temperature thw are reference temperatures is calculated. G/N-wot (tha, thw) are calculated by applying corrections to incorporate the effects of tha and thw in the reference G/N-wot (S102 to S106). A load factor kload considered appropriate as an actual value is calculated by dividing the actual measured value of the intake air amount G/N per rotation by G/N-wot (tha, thw) (S110). Based on the load factor kload, an intake pipe pressure PM is calculated (S112). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an intake pipe negative pressure correlation value estimation system, and more particularly to an intake pipe negative pressure correlation value estimation system suitable as a system for accurately detecting an intake pipe negative pressure correlation value in an internal combustion engine equipped with an air flow meter.

  Conventionally, as disclosed in, for example, Japanese Patent Laid-Open No. 7-293297, a system for estimating an intake pipe negative pressure based on an output of an air flow meter disposed in an intake passage of an internal combustion engine is known. More specifically, in this system, the amount of air passing through the throttle valve is detected by an air flow meter, and the intake pipe negative pressure is estimated based on the amount of air. Based on the estimated intake pipe negative pressure and engine speed, the amount of air taken into the internal combustion engine is calculated in a linear form.

JP 7-293297 A

  By the way, the relationship between the amount of air present in the intake pipe and the intake pipe negative pressure changes as the volumetric efficiency of the air changes. Therefore, the relationship between the amount of air passing through the throttle valve and the intake pipe negative pressure also shows a change according to the change in volumetric efficiency of air existing in the intake system. The volumetric efficiency easily varies depending on how much the air is heated inside the intake pipe or the combustion chamber.

  Furthermore, the heat receiving state of the air present in the intake system varies greatly depending on the temperature of the intake system, that is, the warm-up state of the internal combustion engine. For this reason, depending on the conventional system described above, it is difficult to accurately estimate the intake pipe negative pressure in the entire region from the cold start to the end of warm-up.

  The present invention has been made to solve the above-described problems, and the intake pipe negative pressure correlation value is always calculated based on the intake air amount detected by the air flow meter regardless of the warm-up state of the internal combustion engine. An object of the present invention is to provide an intake pipe negative pressure correlation value estimation system capable of estimating with high accuracy.

In order to achieve the above object, a first invention is a system for estimating an intake pipe negative pressure correlation value having a correlation with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
A received heat amount correlation value detecting means for detecting a received heat amount correlation value correlated with the received heat amount of the intake air;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount, the maximum intake air amount, and the heat reception amount correlation value;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The load factor calculation means is configured such that the smaller the heat reception amount correlation value, the smaller the load factor relative to a reference load factor obtained by dividing the intake air amount by the maximum intake air amount. It is characterized by calculating.

The second invention is the first invention, wherein
The maximum intake air amount estimation means estimates the maximum intake air amount on the assumption that the heat reception amount correlation value is a reference value,
The load factor calculating means includes
Correction means for correcting the maximum intake air amount to a larger value as the heat reception amount correlation value is smaller;
And calculating means for calculating the load factor by dividing the intake air amount by the corrected maximum intake air amount.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the intake pipe negative pressure correlation value is the intake pipe negative pressure itself of the internal combustion engine.

Moreover, 4th invention is set in 3rd invention,
A canister for adsorbing and holding evaporated fuel;
A purge passage for conducting the canister to the intake passage;
A purge control valve for controlling a conduction state of the purge passage;
Maximum purge flow rate estimating means for estimating a maximum purge flow rate obtained by fully opening the purge control valve based on the intake pipe negative pressure;
And a target opening setting means for setting a target opening of the purge control valve based on a ratio between the required purge flow rate and the maximum purge flow rate.

The fifth invention is the first invention, wherein
The load factor calculating means includes
Correction means for correcting the intake air amount to a larger value as the heat reception amount correlation value is larger;
And calculating means for calculating the load factor by dividing the corrected intake air amount by the maximum intake air amount.

The sixth invention is the first invention, wherein
The load factor calculating means calculates the load factor so as to eliminate the influence of the heat reception amount correlation value on the maximum intake air amount;
The negative pressure correlation value calculation means further comprises correction means for correcting the heat reception amount correlation value so as to eliminate the influence on the intake air amount,
The correction means corrects the negative pressure correlation value to a lower negative pressure value as the heat receiving amount correlation value is larger.

The seventh invention is a system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
A received heat amount correlation value detecting means for detecting a received heat amount correlation value correlated with the received heat amount of the intake air;
Reference load factor calculating means for obtaining a reference load factor of the internal combustion engine by dividing the intake air amount by the maximum intake air amount;
A relationship setting means for setting a relationship between the reference load factor and the intake pipe negative pressure correlation value based on the heat reception amount correlation value;
And a negative pressure correlation value calculating means for calculating an intake pipe negative pressure correlation value corresponding to the reference load factor based on the relationship.

The eighth invention is the seventh invention, wherein
The maximum intake air amount estimation means estimates the maximum intake air amount on the assumption that the heat reception amount correlation value is a reference value,
The relationship setting means sets the relationship between the two so that the intake pipe negative pressure correlation value corresponding to the reference load factor becomes larger as the heat reception amount correlation value is smaller.

The ninth invention is the eighth invention, wherein
A canister for adsorbing and holding evaporated fuel;
A purge passage for conducting the canister to the intake passage;
A purge control valve for controlling a conduction state of the purge passage,
The intake pipe negative pressure correlation value is a maximum purge flow rate obtained by fully opening the purge control valve,
The apparatus further comprises target opening setting means for setting a target opening of the purge control valve based on a ratio between the required purge flow rate and the maximum purge flow rate.

A tenth aspect of the invention is a system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Correction means for correcting the intake air amount per rotation of the internal combustion engine calculated based on the intake air amount based on the intake air amount;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the corrected intake air amount and the maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The correction means includes
The corrected intake air amount is calculated as a larger value as the intake air amount is smaller.

An eleventh aspect of the invention is a system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Correction means for correcting the maximum intake air amount based on the intake air amount;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the corrected maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The correction means includes
The corrected maximum intake air amount is calculated as a smaller value as the intake air amount is smaller.

A twelfth aspect of the invention is a system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the maximum intake air amount;
Correction means for correcting the load factor based on the intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the corrected load factor,
The correction means includes
The corrected load factor is calculated as a larger value as the intake air amount is smaller.

A thirteenth aspect of the invention is a system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the corrected maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor;
Correcting means for correcting the negative pressure correlation value based on the intake air amount;
The correction means includes
The corrected negative pressure correlation value is calculated as a low negative pressure value as the intake air amount decreases.

The fourteenth invention is the invention according to any one of the tenth to thirteenth inventions,
The correction means performs correction so as to eliminate a change in the intake pipe negative pressure correlation value due to a change in the maximum intake air amount due to the intake air amount.

Further, a fifteenth aspect of the invention is any of the tenth to thirteenth aspects of the invention,
The correction means performs correction so as to eliminate a change in the intake pipe negative pressure correlation value due to a change in the intake air amount per one rotation of the internal combustion engine due to the intake air amount.

  According to the first aspect of the invention, the load factor of the internal combustion engine can be calculated to be larger than the reference load factor as the heat reception amount correlation value is larger. The reference load factor is a value calculated by dividing the intake air amount actually measured by the air flow meter by the maximum intake air amount estimated based on the engine speed. The actual maximum intake air amount increases as the volumetric efficiency of the air inside the intake system increases. The volumetric efficiency increases as the amount of heat received by the intake air decreases, that is, as the heat reception amount correlation value decreases. For this reason, the actual load factor becomes smaller with respect to the reference load factor as the heat reception amount correlation value is smaller. According to the present invention, it is possible to calculate the load factor in accordance with the actual value by considering the heat reception amount correlation value. Therefore, according to the present invention, the intake pipe negative pressure correlation value can always be calculated with high accuracy without being affected by the amount of heat received by the intake air.

  According to the second invention, the maximum intake air amount is estimated on the assumption that the heat reception amount correlation value is the reference value. In calculating the load factor, the maximum intake air amount is corrected to a larger value as the heat receiving correlation value is smaller. As a result, the corrected maximum intake air amount becomes a correct value reflecting the volumetric efficiency of the intake air. Therefore, according to the present invention, the correct load factor in accordance with the actual value can be calculated by dividing the actually measured intake air amount by the corrected maximum intake air amount.

  According to the third aspect, the intake pipe negative pressure of the internal combustion engine can be accurately estimated based on the accurately estimated load factor.

  According to the fourth aspect of the invention, the maximum purge flow rate can be accurately calculated based on the accurately estimated intake pipe negative pressure. If the maximum purge flow rate can be calculated accurately, the opening degree of the purge control valve for generating the required purge flow rate can be set accurately. Therefore, according to the present invention, the purge flow rate can be accurately controlled without being affected by the amount of heat received by the intake air.

  According to the fifth aspect of the invention, when calculating the load factor, the intake air amount is corrected to a larger value as the heat receiving correlation value is larger. As a result, the corrected intake air amount becomes a correct value reflecting the volumetric efficiency of the intake air. Therefore, according to the present invention, the correct load factor in accordance with the actual value can be calculated by dividing the corrected intake air amount by the maximum intake air amount.

  According to the sixth invention, the calculated negative pressure correlation value is corrected to a lower negative pressure value as the heat receiving amount correlation value is larger. As a result, the corrected negative pressure correlation value is a correct value reflecting the volumetric efficiency of the intake air. For this reason, according to the present invention, it is possible to calculate a correct negative pressure correlation value in accordance with an actual value.

  According to the seventh aspect, the reference load factor is calculated by dividing the actually measured intake air amount by the maximum intake air amount estimated based on the engine speed. The actual load factor has a smaller value with respect to the reference load factor as the received heat amount correlation value is lower and the volumetric efficiency of the intake air increases. The intake pipe negative pressure correlation value maintains a constant relationship with the actual load factor. Therefore, the relationship between the intake pipe negative pressure correlation value and the reference load factor shows a change according to the heat reception correlation value. According to the present invention, the relationship between the two is set based on the received heat amount correlation value, and the intake pipe negative pressure correlation value corresponding to the reference load factor is calculated according to the relationship. Therefore, according to the present invention, the intake pipe negative pressure correlation value can always be correctly calculated without being affected by the amount of heat reception amount correlation value.

  According to the eighth invention, the maximum intake air amount is estimated on the assumption that the heat reception amount correlation value is the reference value. Therefore, the actual load factor becomes smaller with respect to the reference load factor as the volumetric efficiency of the intake air increases as the received heat amount correlation value becomes lower than the reference value. The intake pipe negative pressure correlation value increases as the load factor decreases. For this reason, the intake pipe negative pressure correlation value corresponding to the reference load factor tends to be larger as the heat reception amount correlation value is smaller. According to the present invention, the relationship between the reference load factor and the intake pipe negative pressure correlation value is set so as to exhibit the above-described tendency corresponding to the degree of the heat receiving amount correlation value. Therefore, according to the present invention, the intake pipe negative pressure correlation value can always be calculated as a correct value without being affected by the amount of heat reception amount correlation value.

  According to the ninth aspect, the maximum purge flow rate can be correctly calculated based on the relationship set based on the heat reception amount correlation value. If the maximum purge flow rate can be calculated accurately, the opening degree of the purge control valve for generating the required purge flow rate can be set accurately. Therefore, according to the present invention, the purge flow rate can be accurately controlled without being affected by the amount of heat received by the intake air.

  According to the tenth aspect of the invention, it is possible to eliminate the influence on the amount of heat received by the intake air due to the amount of intake air and always calculate the intake pipe negative pressure correlation value with high accuracy. That is, the smaller the amount of intake air, the greater the effect of the amount of heat received by the intake air. Therefore, by correcting the intake air amount per one rotation of the internal combustion engine based on the intake air amount, the corrected intake air amount can be calculated to be larger as the intake air amount is smaller. As a result, the corrected intake air amount becomes a correct value reflecting the volumetric efficiency of the intake air. Therefore, by calculating the load factor based on the corrected intake air amount, it is possible to calculate the negative pressure correlation value that matches the actual value.

  According to the eleventh aspect of the invention, it is possible to eliminate the influence on the amount of heat received by the intake air due to the amount of intake air and always calculate the intake pipe negative pressure correlation value with high accuracy. That is, the smaller the intake air amount, the greater the influence of the amount of heat received by the intake air. Therefore, by correcting the maximum intake air amount based on the intake air amount, the corrected maximum intake air amount can be calculated as a smaller value as the intake air amount is smaller. As a result, the corrected maximum intake air amount becomes a correct value reflecting the volumetric efficiency of the intake air. Therefore, by calculating the load factor based on the corrected maximum intake air amount, it is possible to calculate the negative pressure correlation value that matches the actual value.

  According to the twelfth aspect, it is possible to eliminate the influence of the intake air amount on the heat reception amount of the intake air and always calculate the intake pipe negative pressure correlation value with high accuracy. That is, the smaller the intake air amount, the greater the influence of the amount of heat received by the intake air. Therefore, by correcting the load factor based on the intake air amount, the corrected load factor can be calculated to be larger as the intake air amount is smaller. As a result, the corrected load factor becomes a correct value reflecting the volumetric efficiency of the intake air, and a negative pressure correlation value in accordance with the actual value can be calculated.

  According to the thirteenth aspect, it is possible to eliminate the influence on the amount of heat received by the intake air due to the amount of intake air and always calculate the intake pipe negative pressure correlation value with high accuracy. That is, the smaller the intake air amount, the greater the influence of the amount of heat received by the intake air. Therefore, by correcting the negative pressure correlation value based on the intake air amount, the corrected intake pipe negative pressure can be calculated as a lower negative pressure value as the intake air amount is smaller. As a result, the corrected negative pressure correlation value is a correct value reflecting the volumetric efficiency of the intake air, and the negative pressure correlation value in accordance with the actual value can be calculated.

  According to the fourteenth aspect, the influence of the maximum intake air amount caused by the intake air amount on the heat receiving amount can be eliminated, and the intake pipe negative pressure correlation value can always be calculated with high accuracy. The influence of the maximum intake air amount on the amount of heat received increases as the intake air amount decreases. That is, the actual maximum intake air amount becomes smaller as the intake air amount is smaller than a value calculated without considering the influence of the intake air amount. According to the present invention, the intake air amount per one rotation of the internal combustion engine, the maximum intake air amount, the load factor, or the intake pipe negative pressure correlation value is corrected based on the intake air amount, and an actual value is obtained. It is possible to calculate the correct maximum intake air amount in accordance with the above.

  According to the fifteenth aspect, it is possible to eliminate the influence of the intake air amount per revolution of the internal combustion engine caused by the intake air amount and to calculate the intake pipe negative pressure correlation value with high accuracy at all times. it can. The effect of the intake air amount per revolution of the internal combustion engine on the amount of heat received increases as the intake air amount decreases. That is, the actual intake air amount per rotation of the internal combustion engine becomes a value larger than the value calculated without considering the influence of the intake air amount as the intake air amount is smaller. According to the present invention, the intake air amount per one rotation of the internal combustion engine, the maximum intake air amount, the load factor, or the intake pipe negative pressure correlation value is corrected based on the intake air amount, A correct intake air amount per one rotation of the internal combustion engine can be calculated in accordance with the value.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes a canister 10. A fuel tank (not shown) is connected to the canister 10 via a vapor passage 12. The canister 10 can adsorb and hold the evaporated fuel (vapor) generated inside the fuel tank and flowing through the vapor passage 12.

  The canister 10 is provided with an air introduction hole 14 and one end of a purge passage 16 communicates therewith. The purge passage 16 communicates with the intake passage 18 of the internal combustion engine at the other end. Hereinafter, the communication point between the purge passage 16 and the intake passage 18 is referred to as a purge port 20.

  A purge VSV (Vacuum Switching Valve) 22 is disposed in the middle of the purge passage 16. The purge VSV 22 is a control valve that opens and closes at an arbitrary duty ratio by being driven by a duty and, as a result, realizes an arbitrary opening degree.

  A throttle valve 24 is disposed in the intake passage 18 on the upstream side of the purge port 20. An air flow meter 26 is provided further upstream of the throttle valve 24. The air flow meter 26 is a sensor that detects an intake air amount Ga flowing through the intake passage 18 upstream of the throttle valve 24 by a mass flow rate (g / sec).

  An intake air temperature sensor 28 is disposed in the vicinity of the air flow meter 26. The intake air temperature sensor 28 can detect the temperature tha of the intake air when it passes through the air flow meter 26. An air filter 30 is disposed further upstream of the air flow meter 26.

  The intake passage 18 communicates with the intake port 34 of the internal combustion engine 32 downstream of the surge tank. The internal combustion engine 32 incorporates a water temperature sensor 36 for detecting the cooling water temperature thw and a rotational speed sensor 38 for detecting the engine rotational speed NE.

  The system of this embodiment includes an ECU (Electronic Control Unit) 40 as shown in FIG. The output of the air flow meter 26, the output of the intake air temperature sensor 28, the output of the water temperature sensor 36, and the like are supplied to the ECU 40. The ECU 40 performs processing such as estimation of the intake pipe negative pressure PM and control of the purge VSV 22 based on these sensor outputs.

[Operation of Embodiment 1]
Next, the operation of this embodiment will be described with reference to FIGS.
The system of the present embodiment can accurately estimate the intake pipe negative pressure PM, that is, the pressure PM in the intake passage 18 downstream of the throttle valve 24, based on the intake air amount Ga actually measured by the air flow meter 26. it can.

FIG. 2 shows the relationship between the load factor kload of the internal combustion engine 32 and the intake pipe negative pressure PM. Here, the “load factor kload” shown in FIG. 2 is a value representing the ratio of G / N and G / N-wot as a percentage, as represented by the following equation.
kload = (G / N) / (G / N-wot) * 100 (1)

  In the above equation (1), “G / N” is the intake air amount (mass) per revolution of the internal combustion engine 10, while “G / N-wot” is the throttle valve 24. This is the intake air amount (mass) per rotation generated under the fully open condition, that is, the maximum intake air amount per rotation. Hereinafter, for convenience, G / N and G / N-wot are simply referred to as “intake air amount” and “maximum intake air amount”, respectively.

  In FIG. 2, the vertical axis represents the magnitude of the negative pressure. The load factor kload becomes 100% when the throttle valve 24 is fully opened. In this case, since the inside of the intake passage 18 is opened to the atmospheric pressure, the intake pipe negative pressure PM becomes “0”. Then, as shown in FIG. 2, the intake pipe negative pressure PM changes substantially in proportion to the change in the load factor kload. Therefore, if the load factor kload can be detected accurately, the intake pipe negative pressure PM can be accurately obtained by using the relationship shown in FIG.

  The intake air amount G / N can be calculated based on the intake air amount (g / sec) measured by the air flow meter 26 and the engine rotational speed NE (rpm) detected by the rotational speed sensor 38. is there. On the other hand, the maximum intake air amount G / N-wot can be determined almost uniquely in relation to the engine speed NE if the volumetric efficiency ηv of the intake air is constant. For this reason, when the volumetric efficiency ηv is constant, it is possible to accurately detect both the intake air amount G / N and the maximum intake air amount G / N-wot and accurately calculate the load factor kload. It is.

  However, the volumetric efficiency ηv of the air inside the intake passage 18 changes according to the temperature of the intake air, that is, the intake air temperature tha. As a result, the maximum intake air amount G / N-wot varies depending on the influence of the intake air temperature tha.

  FIG. 3A is a diagram for explaining the dependency of the maximum intake air amount G / N-wot on the intake air temperature tha. The relationship shown in FIG. 3 (A) shows a relationship that is established between the intake air temperature tha and the maximum intake air amount G / N-wot under the condition where the engine speed NE and the coolant temperature thw are constant. . The volumetric efficiency ηv of the intake air becomes higher as the intake temperature tha is lower. Further, the maximum intake air amount G / N-wot increases as the volumetric efficiency ηv increases. For this reason, as shown in FIG. 3A, the maximum intake air amount G / N-wot tends to increase as the intake air temperature tha decreases.

  A curve indicated by a solid line in FIG. 3B shows a relationship established between G / N-wot and NE when the intake air temperature tha is 20 ° C. In addition, the curve indicated by the broken line in this figure shows the relationship established between G / N-wot and NE when the intake air temperature tha is 30 ° C. However, these relations are all established under the situation where the coolant temperature thw is 90 ° C., that is, the situation where the internal combustion engine 32 is completely warmed up. These relationships indicate that the tendency that the maximum intake air amount G / N-wot increases as the intake air temperature tha decreases appears throughout the engine speed NE.

  The volumetric efficiency ηv inside the intake passage 18 also changes depending on the amount of heat received by the intake air after passing through the throttle valve 24. That is, the volumetric efficiency ηv increases as the amount of heat received by the intake air decreases in the process of flowing through the intake passage 18. For this reason, the maximum intake air amount G / N-wot has different values due to the influence of the wall surface temperature of the intake passage 18 and the wall surface temperature of the combustion chamber, and hence the cooling water temperature thw.

  FIG. 4A is a diagram for explaining the dependency of the maximum intake air amount G / N-wot on the cooling water temperature thw. The relationship shown in FIG. 4A is a relationship that is established between the cooling water temperature thw and the maximum intake air amount G / N-wot under the condition where the engine speed NE and the intake air temperature tha are constant. . The volumetric efficiency ηv of the intake air increases as the cooling water temperature thw decreases and the amount of heat received by the intake air decreases. Further, the maximum intake air amount G / N-wot increases as the volumetric efficiency ηv increases. For this reason, as shown in FIG. 4A, the maximum intake air amount G / N-wot tends to increase as the cooling water temperature thw decreases.

  The curve indicated by the solid line in FIG. 4B shows the relationship established between G / N-wot and NE under conditions where the coolant temperature thw is 90 ° C, that is, under the condition of complete warm-up. Show. Further, the curve indicated by a broken line in this figure shows the relationship established between G / N-wot and NE when the coolant temperature thw is 20 ° C., that is, when the internal combustion engine is cold. However, these relationships are all established under the situation where the intake air temperature tha is 20 ° C. These relations indicate that the tendency that the maximum intake air amount G / N-wot increases as the cooling water temperature thw decreases appears throughout the engine speed NE.

  By the way, the curve shown by the solid line in FIG. 3B is a characteristic of the maximum intake air amount G / N-wot that is established under the condition that the intake air temperature tha is 20 ° C. and the cooling water temperature thw is 90 ° C. Represents. The curve indicated by the solid line in FIG. 4 (B) is exactly the same as the maximum intake air amount G / N-wot that is established under the condition that the intake air temperature tha is 20 ° C. and the coolant temperature thw is 90 ° C. Represents the characteristics. 20 ° C. is a normal value as the intake air temperature tha, and 90 ° C. is a normal value of the cooling water temperature thw after complete warm-up. Hereinafter, the above G / N-wot characteristics established under these temperature environments are referred to as “reference G / N-wot characteristics”, and G / N-wot satisfying this relationship is referred to as “reference G / N-wot”. I will call it.

  FIG. 5 is a diagram showing the relationship established between the reference load factor and the intake pipe negative pressure PM in a case where the cooling water temperature thw is 90 ° C. and 20 ° C. Here, the “reference load factor” is a load factor calculated by substituting the measured value for the intake air amount G / N and substituting the reference G / N-wot for the maximum intake air amount G / N-wot. kload (see equation (1) above). Here, the intake air temperature tha is assumed to be 20 ° C.

  Under the situation where the cooling water temperature thw is 90 ° C., the actual maximum intake air amount G / N-wot matches the reference G / N-wot. That is, in this case, when the throttle valve 24 is fully opened, an intake air amount G / N that matches the reference G / N-wot is generated. For this reason, when the cooling water temperature thw is 90 ° C., the intake pipe negative pressure PM is 0 under the condition that the reference load factor is calculated as 100%, and between the reference load factor and the intake pipe negative pressure PM. Is established as shown by a solid line in FIG.

That is, if the internal combustion engine 10 is completely warmed up, the relationship between the reference load factor kload and the intake pipe negative pressure PM satisfies the relationship indicated by the solid line in FIG. Therefore, in this case, the intake pipe negative pressure PM can be correctly calculated by the following method.
(I) The reference G / N-wot characteristic is stored in the ECU 40. Based on the characteristics, the maximum intake air amount G / N-wot corresponding to the engine speed NE is calculated.
(Ii) The reference load factor is calculated by substituting the calculated maximum intake air amount G / N-wot and the actually measured intake air amount G / N into the above equation (1).
(Iii) The relationship indicated by the solid line in FIG. 5 is stored in the ECU 40. In accordance with the relationship, the intake pipe negative pressure PM corresponding to the reference load factor is read out.

  On the other hand, when the coolant temperature thw is 20 ° C., the throttle valve 24 is fully opened, so that the intake air amount G / N exceeding the reference G / N-wot flows into the intake passage 18. Therefore, in this case, the reference load factor is calculated to a value larger than 100% (for example, 110%) under a situation where the throttle valve 24 is fully opened, that is, under a situation where the intake pipe negative pressure PM is zero. . At this time, the relationship between the reference load factor and the intake pipe negative pressure PM is as shown by a broken line in FIG.

  According to the above methods (i) to (iii), even in this case, the intake pipe negative pressure PM is calculated as 0 if the reference load factor is calculated as 100%. That is, in reality, even if the throttle valve 24 is not fully opened and the intake pipe negative pressure PM has not increased to atmospheric pressure, if the reference load factor is calculated as 100%, the intake pipe negative pressure is calculated. The pressure PM is erroneously set to zero. Thus, depending on the methods (i) to (iii), the intake pipe negative pressure PM cannot be correctly estimated under a situation where the coolant temperature thw deviates from 90 ° C.

  The same situation applies to the intake air temperature tha. That is, when the intake air temperature tha is 20 ° C., which is the precondition temperature of the reference G / N-wot characteristic, the intake pipe negative pressure PM can be correctly calculated by the methods (i) to (iii). When the intake air temperature tha is not 20 ° C., the intake pipe negative pressure PM cannot be estimated correctly depending on the method.

  Therefore, in the present embodiment, by applying correction to the reference load factor in consideration of the effects of the intake air temperature tha and the cooling water temperature thw, the load factor kload in accordance with the actual value is calculated, and based on the load factor kload, The intake pipe pressure PM is estimated according to the relationship indicated by the solid line in FIG.

[Specific Processing in Embodiment 1]
FIG. 6 is a flowchart of a routine executed by the ECU 40 in order to estimate the intake pipe negative pressure PM by the above procedure. In the routine shown in FIG. 6, first, the intake air temperature tha, the intake air amount Ga, and the engine speed NE are taken in (step 100).

  Next, the maximum intake air amount G / N-wot (hereinafter referred to as “G / N-wot (tha)”) is calculated so as to reflect the influence of the intake air temperature tha (step 102). The ECU 40 stores the above-described reference G / N-wot characteristic (characteristic indicated by a solid line in FIGS. 3B and 4B). Specifically, first, a reference G / N-wot corresponding to the current engine speed NE is specified based on the reference G / N-wot characteristic. Next, a correction coefficient Ka for reflecting the influence of the intake air temperature tha is calculated.

  FIG. 7 shows a map stored in the ECU 40 for calculating the correction coefficient Ka. In step 102, the correction coefficient Ka is calculated according to this map. According to this map, the correction coefficient Ka is 1.0 when the intake air temperature tha is 20 ° C., which is the precondition temperature of the reference G / N-wot characteristic, and becomes smaller as the intake air temperature tha increases. Is done.

  In step 102, next, the reference G / N-wot is multiplied by the correction coefficient Ka, and the result is stored as G / N-wot (tha). The volumetric efficiency ηv of the intake air decreases as the intake temperature tha increases. For this reason, the actual maximum intake air amount G / N-wot decreases as the intake air temperature tha increases. According to the correction coefficient Ka described above, the tendency can be correctly reflected in G / N-wot (tha). Therefore, according to the above processing, it is possible to calculate the maximum intake air amount G / N-wot (tha) in accordance with the actual value in consideration of the influence of the intake temperature tha.

  In the routine shown in FIG. 6, next, the coolant temperature thw is taken in (step 104). Next, the maximum intake air amount G / N-wot (hereinafter referred to as “G / N-wot (tha, thw)”) is calculated so as to reflect the influence of the cooling water temperature thw (step 106). Specifically, first, a correction coefficient Kw for reflecting the influence of the cooling water temperature thw is calculated.

  FIG. 8 shows a map stored in the ECU 40 for calculating the correction coefficient Kw. In step 106, the correction coefficient Kw is calculated according to this map. According to this map, the correction coefficient Kw is 1.0 when the cooling water temperature thw is 90 ° C., which is the precondition temperature of the reference G / N-wot characteristic, and increases as the intake air temperature tha decreases. Is done.

  Next, in step 106, G / N-wot (tha) calculated by taking into account the influence of the intake air temperature tha is multiplied by the correction coefficient Kw, and the result is G / N-wot (tha, thw ). The volumetric efficiency ηv of the intake air increases as the amount of heat received by the intake air decreases. For this reason, the actual maximum intake air amount G / N-wot increases as the cooling water temperature thw decreases. According to the correction coefficient Kw described above, the tendency can be correctly reflected in G / N-wot (tha, thw). Therefore, according to the above processing, G / N-wot (tha, thw) that accurately matches the actual maximum intake air amount G / N-wot is calculated in consideration of the influence of the cooling water temperature thw. Can do.

  In the routine shown in FIG. 6, next, the intake air amount G / N per rotation is calculated based on the actually measured value of the intake air amount Ga and the engine speed NE (step 108). Next, the G / N and the G / N-wot (tha, thw) obtained in step 106 are substituted into the above equation (1) to calculate the load factor kload (step 110). G / N-wot (tha, thw) matches the actual maximum intake air amount G / N-wot with high accuracy regardless of the intake air temperature tha and the cooling water temperature thw. For this reason, according to the above processing, it is possible to correctly calculate the load factor kload in accordance with the actual value under any temperature environment.

  Next, the ECU 40 estimates the intake pipe negative pressure PM based on the load factor kload (step 112). The ECU 40 stores a map that defines the relationship between the load factor kload and the intake pipe negative pressure PM (see the solid line in FIG. 5). Here, the intake pipe negative pressure PM corresponding to the load factor kload calculated in step 110 is specified according to the map. According to the above processing, the intake pipe negative pressure PM can always be accurately estimated regardless of the level of the intake air temperature tha and regardless of the warm-up state of the internal combustion engine 32.

In the present embodiment, the intake pipe negative pressure PM estimated by the above processing is used for the purge control of the evaporated fuel.
FIG. 9 is a flowchart of a routine executed by the ECU 40 as part of the purge control. In the routine shown in FIG. 9, first, the maximum purge flow rate Pmax is calculated based on the intake pipe negative pressure PM (step 120). The maximum purge flow rate Pmax is a purge flow rate that occurs when the purge VSV 22 is fully opened, and its value is uniquely determined by the intake pipe pressure PM.

  FIG. 10 shows a map stored in the ECU 40 for calculating the maximum purge flow rate Pmax. When the intake pipe pressure PM is α shown in FIG. 10, for example, the maximum purge flow rate Pmax is calculated as 0.8 (g / sec) according to this map. In the present embodiment, since the intake pipe pressure PM is accurately calculated, the maximum purge flow rate Pmax can be accurately calculated by the above processing.

  In the routine shown in FIG. 9, next, the required purge rate PGR is fetched (step 122). The required purge rate PGR is a target value of the ratio of the purge flow rate QPG to the intake air amount Ga. The ECU 40 calculates the value PGR by another routine based on the operating state of the internal combustion engine 32 and the like. Here, the value PGR is taken in.

Next, the required purge flow rate is calculated according to the following arithmetic expression (step 124).
Required purge flow rate = Intake air amount Ga x Required purge rate PGR (2)

  For example, if the intake air amount is 10 (g / sec) and the required purge rate PGR is 4%, the required purge flow rate is calculated as 0.4 (g / sec).

Next, the control duty value of the purge VSV 22 is calculated according to the following equation (step 126).
Control Duty value = required purge flow rate / maximum purge flow rate Pmax × 100 (3)

  For example, when the required purge flow rate is 0.4 (g / sec) and the maximum purge flow rate Pmax is 0.8 (g / sec), the control duty value is set to 50%. The purge VSV 22 substantially realizes an opening corresponding to the control duty value. For this reason, when the purge VSV 22 is controlled with the control duty value calculated by the above equation (3), the required purge flow rate can be realized with high accuracy.

  As described above, according to the system of the present embodiment, the intake pipe is always accurately and without being influenced by the intake air temperature tha or the warm-up state of the internal combustion engine 32, based on the intake air amount Ga and the engine speed NE. Negative pressure PM can be calculated. The purge flow rate can be accurately controlled using the intake pipe negative pressure PM. For this reason, according to the system of the present embodiment, accurate purge control can be realized not only after complete warm-up but also during the warm-up process of the internal combustion engine 10.

  In the first embodiment described above, the method of accurately estimating the intake pipe negative pressure PM in consideration of the intake air temperature tha and the cooling water temperature thw is executed in combination with the purge control. It is not always required. That is, the above-described estimation of the intake pipe negative pressure PM may be executed separately from the purge control, and the estimated PM may be used for another control different from the purge control.

  In Embodiment 1 described above, the influence of the amount of heat received by the intake air is reflected in the load factor kload by the cooling water temperature thw. However, the method for reflecting the influence is not limited to this. Absent. That is, the amount of heat received by the intake air has a correlation with the wall surface temperature of the intake passage 18 and the wall surface temperature of the combustion chamber in addition to the coolant temperature thw. For this reason, after acquiring those wall surface temperatures, based on the wall surface temperature, it is good also as reflecting the influence of the received heat amount of intake air on the load factor kload.

  Further, in the first embodiment described above, the effects of the intake air temperature tha and the cooling water temperature thw are reflected in the maximum intake air amount G / N-wot, and based on G / N-wot (tha, thw) Although the load factor kload corresponding to the value is obtained, the calculation procedure is not limited to this. That is, based on the intake air amount G / N and the maximum intake air amount G / N-wot, first, a reference load factor is calculated, and in order to reflect the influence of the intake air temperature tha and the cooling water temperature thw on the reference load factor. The final load factor kload may be calculated by performing the above correction.

  In the first embodiment described above, the cooling water temperature thw corresponds to the “heat receiving amount correlation value” in the first invention, and the ECU 40 calculates the reference G / N-wot in step 102. As a result, the “maximum intake air amount estimating means” in the first invention executes the process of step 104, so that the “heat reception amount correlation value detecting means” in the first invention performs the process of step 110. By executing this, the “load factor calculating means” in the first invention realizes the “negative pressure correlation value calculating means” in the first invention by executing the processing of step 112.

  In the first embodiment described above, the ECU 40 executes the process of step 106, so that the “correction means” in the second invention executes the process of step 110. The “calculation means” in the invention is realized respectively.

  In the first embodiment described above, the purge VSV 22 corresponds to the “purge control valve” in the fourth aspect of the invention, and the ECU 40 executes the processing of step 120 described above to execute the fourth aspect of the invention. The “maximum purge flow rate estimating means” in FIG. 6 implements the “target opening degree setting means” in the fourth aspect of the invention by executing the processing of step 126 described above.

Embodiment 2. FIG.
[Features of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG. 11 and FIG. The system of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 11 to be described later using the hardware configuration shown in FIG.

  In the first embodiment described above, the relationship indicated by the solid line in FIG. 5 is always established between the load factor kload and the intake pipe pressure PM, and the influence of the intake air temperature tha and the cooling water temperature thw is applied to the load factor kload. Reflecting this makes it possible to correctly estimate the intake pipe negative pressure PM. On the other hand, if the relationship between the reference load factor and the intake pipe pressure PM is appropriately changed according to the intake air temperature tha and the cooling water temperature thw, the correct intake pipe negative pressure PM is set based on the reference load factor. It is possible to calculate.

  In the first embodiment described above, the intake pipe negative pressure PM is obtained from the load factor kload, and the maximum purge flow rate Pmax is calculated from the intake pipe negative pressure PM. However, since the relationship between the intake pipe negative pressure PM and the maximum purge flow rate Pmax is unambiguous, if the relationship between the load factor kload and the maximum purge flow rate Pmax is prepared in advance, the intake pipe negative pressure PM is interposed. The maximum purge flow rate Pmax can be directly obtained from the load factor kload.

That is, the maximum purge flow rate Pmax can be correctly calculated not only by the method of the first embodiment but also by the following method.
(I) The relationship between the reference load factor (the value obtained by dividing the measured value of the intake air amount G / N by the reference G / N-wot) and the maximum purge flow rate Pmax, in advance using the intake air temperature tha and the cooling water temperature thw as parameters. Prepare multiple types.
(Ii) An appropriate relationship is specified from the plurality of relationships according to the actually measured values of the intake air temperature tha and the cooling water temperature thw.
(Iii) The maximum purge flow rate Pmax corresponding to the reference load factor is read out from the identified relationship.

Further, the above method may be modified as follows in combination with the method of the first embodiment.
(I) One of the intake air temperature tha and the cooling water temperature thw (for convenience, the intake air temperature tha) is reflected in the reference load factor in the same manner as in the first embodiment (the reflected reference load factor is “tha reflection”). Load factor ").
(II) A plurality of relations between the reference load factor and the maximum purge flow rate Pmax are prepared only for the other parameter (here, the cooling water temperature thw).
(III) An appropriate relationship is specified from the plurality of relationships according to the measured value of the other parameter (cooling water temperature thw).
(IV) The maximum purge flow rate Pmax corresponding to the tha reflection load factor is read from the identified relationship.

Hereinafter, the procedure in which the system of the present embodiment calculates the maximum purge flow rate Pmax by the methods (I) to (IV) will be specifically described.
FIG. 11 is a flowchart of a routine executed by the ECU 40 in order to realize the above function. In this routine, first, the intake air temperature tha, the intake air amount Ga, the cooling water temperature thw, and the engine speed NE are taken in (step 130).

  Next, the maximum intake air amount G / N-wot (hereinafter referred to as “G / N-wot (tha)”) is calculated so as to reflect the influence of the intake air temperature tha (step 132). Here, specifically, the same processing as step 102 shown in FIG. 6 is executed.

  Next, the intake air amount G / N per rotation is calculated based on the actually measured value of the intake air amount Ga and the engine speed NE (step 134). Next, the G / N and the G / N-wot (tha) obtained in step 132 are substituted into the equation (1) to calculate the tha reflection load factor kload (tha) (step 136). .

  Next, the maximum purge flow rate Pmax is calculated based on the tha reflection load factor kload (tha) calculated as described above and the cooling water temperature thw taken in step 130 (step 138).

  FIG. 12 is a diagram for specifically explaining the processing in step 138. In the present embodiment, the ECU 40 stores a relationship indicated by a solid line in FIG. 12 (thw = 90 ° C.) and a relationship indicated by a broken line (thw = 20 ° C.) as a map. The former is the relationship between the reference load factor established under thw = 90 ° C. and the maximum purge flow rate Pmax. The latter is the relationship between the reference load factor established under thw = 20 ° C. and the maximum purge flow rate Pmax.

  When the coolant temperature thw is 90 ° C. or 20 ° C., the maximum purge flow rate Pmax corresponding to the tha reflection load factor kload (tha) is calculated according to the corresponding relationship. When the cooling water temperature thw is a value between 90 ° C. and 20 ° C., the maximum purge flow rate Pmax corresponding to the tha reflection load factor kload (tha) is calculated by interpolation calculation.

Specifically, when the coolant temperature thw is 55 ° C. and the tha reflection load factor kload (tha) is 85%, the maximum purge flow rate Pmax is calculated by the following arithmetic expression.
Pmax = Pmax (90) + {Pmax (20) −Pmax (90)} × (90−55) / (90−20) (4)
However, Pmax (90) is the maximum purge flow rate that is assumed to correspond to a load factor of 85% due to the relationship of thw = 90 ° C. Similarly, Pmax (20) is the maximum purge flow rate that is assumed to correspond to a load factor of 85% due to the relationship of thw = 20 ° C. FIG. 12 shows an example in which the maximum purge flow rate Pmax is calculated as 0.8 (g / sec) as a result of the above calculation.

  In the routine shown in FIG. 11, thereafter, the required purge rate PGR is fetched (step 140), the required purge flow rate QPG is calculated (step 142), and the control duty value is calculated (step 144). These processes are the same as the processes of steps 122 to 126 shown in FIG.

  According to the above-described processing, as in the case of the first embodiment, the maximum purge flow rate Pmax can always be accurately calculated without being influenced by the level of the intake air temperature tha and the amount of heat received by the intake air. it can. As a result, also with the system of the present embodiment, high-accuracy purge control can be realized not only after the complete warm-up but also during the warm-up process of the internal combustion engine 32 as in the case of the first embodiment.

  In the second embodiment described above, the maximum purge flow rate Pmax is obtained without obtaining the intake pipe negative pressure PM, but the present invention is not limited to this. That is, instead of the map shown in FIG. 12, a map that defines the relationship between the reference load factor and the intake pipe negative pressure PM may be prepared, and the intake pipe negative pressure PM may be obtained from the reference load factor.

  In the second embodiment described above, the influence of the intake air temperature tha is reflected in the reference load factor, and only a plurality of relationships between the reference load factor and the maximum purge flow rate Pmax are prepared for the cooling water temperature thw. The combination is not limited to this. That is, the influence of the cooling water temperature thw may be reflected in the reference load factor, and a plurality of relationships between the reference load factor and the maximum purge flow rate Pmax may be prepared for the intake air temperature tha.

  Further, according to the above-described procedures (i) to (iii), a plurality of relationships between the reference load factor and the maximum purge flow rate Pmax are prepared for both the intake air temperature tha and the cooling water temperature thw, and the above steps are performed for both of them. The process 138 may be executed.

  In the second embodiment described above, the cooling water temperature thw corresponds to the “heat receiving amount correlation value” in the seventh invention, and the ECU 40 performs G / N-wot (tha) in step 132. The "maximum intake air amount estimating means" in the seventh invention by calculating the above, the "heat reception amount correlation value detecting means" in the seventh invention by taking in the cooling water temperature thw in the step 130, the step By calculating the tha reflection reference load factor kload (tha) in 136, the “reference load factor calculating means” in the seventh invention executes the processing of the above step 138, thereby “relationship setting” in the seventh invention. Means "and" negative pressure correlation value calculating means "are realized.

  In the second embodiment described above, the purge VSV 22 corresponds to the “purge control valve” in the ninth invention, and the ECU 40 executes the process of step 144 to execute the ninth invention. "Target opening degree setting means" is realized.

Embodiment 3 FIG.
[Features of Embodiment 3]
Next, Embodiment 3 of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 14 to be described later using the hardware configuration shown in FIG.

  In the first embodiment described above, the effect of the heat reception amount correlation value on the volumetric efficiency ηv of the intake air is reflected in the maximum intake air amount G / N-wot, so that the load factor kload that matches the actual value is obtained. It is possible to calculate and estimate the correct intake pipe pressure PM. In other words, the volumetric efficiency ηv of the intake air decreases due to heat reception, and as a result, the actual maximum intake air amount G / N-wot becomes a small value, so that the effects of the intake air temperature tha and the cooling water temperature thw should be reflected. Thus, the maximum intake air amount G / N-wot that is realistic is calculated.

  By the way, the correction means considers the effects of the intake air temperature tha and the cooling water temperature thw as the heat reception amount correlation value, but the engine room temperature ther also has a correlation with the heat reception amount of the intake air. Therefore, the maximum intake air amount G / N-wot varies depending on the influence of the engine room temperature ther.

  The influence due to the engine room temperature ther is conspicuous when the vehicle is traveling at low speed and low load after traveling at high speed and high load. In other words, the temperature rise effect of the intake air tends to depend on the engine room temperature ther, and the intake pipe negative pressure PM cannot be correctly estimated only by the correction based on the intake temperature tha and the cooling water temperature thw.

  FIG. 13 is a diagram for explaining the dependence of the engine room temperature on the intake air amount Ga. The solid line shown in this figure shows the intake air amount Ga (g / sec) and engine room temperature (° C) when the vehicle is stopped under the condition that the intake air temperature tha and the cooling water temperature thw are constant. The relationship established between the two is shown. These relations show that the engine room temperature tends to increase as the load increases with a large intake air amount Ga.

  The broken line shown in this figure indicates the relationship established between the intake air amount Ga (g / sec) and the engine room temperature (° C.) when the vehicle is traveling at a speed of 100 km / h. . Comparing the engine room temperature with respect to the solid line and the broken line shown in FIG. 14, these relationships indicate that the tendency that the engine room temperature decreases as the vehicle speed increases appears throughout the intake air amount Ga.

  Therefore, an accurate engine room temperature can be estimated by taking into consideration the influence of engine room heating due to the engine load, that is, the amount of intake air amount Ga, and the influence of cooling due to traveling wind.

  Therefore, in this embodiment, first, an accurate engine room temperature ther is estimated. Then, by reflecting the influence of the estimated engine room temperature ther to the maximum intake air amount G / N-wot, the load factor kload is calculated in consideration of the influence of the intake air heat that does not appear in the cooling water temperature thw, etc. Based on the load factor kload, the intake pipe negative pressure PM in accordance with the actual value was estimated.

[Specific Processing in Embodiment 3]
FIG. 14 is a flowchart of a routine that the ECU 40 executes to estimate the intake pipe negative pressure PM. In this routine, first, the intake air temperature tha, the intake air amount Ga, and the engine speed NE are taken in (step 200), and then G / N-wot (tha) so that the influence of the intake air temperature tha is reflected. Is calculated (step 202).

  Next, the cooling water temperature thw is taken in (step 204), and G / N-wot (tha, thw) is calculated so that the influence of the cooling water temperature thw is reflected (step 206). Specifically, steps 200 to 206 are the same processes as steps 100 to 106 shown in FIG. 6 which is the flowchart of the first embodiment.

  Next, engine room max temperature thermax, engine room heating amount cther, and engine room heating integrated amount CTHER are obtained (step 208). The engine room max temperature thermax is the maximum temperature of the engine room when the vehicle is stopped. FIG. 15 shows the relationship between the engine room max temperature thermax and the intake air amount Ga. This figure shows how thermax increases as the intake air amount Ga increases. The ECU 40 stores a map that defines the relationship shown in FIG. Here, the thermax corresponding to the current intake air amount Ga is specified based on the map.

  Next, the engine room heating amount cther is obtained. The engine room temperature rises due to engine heat generation. Here, the amount of heat that the engine room receives from the engine is the engine room heating amount cther. FIG. 16 shows the relationship between the engine room heating amount cther and the intake air amount Ga. The amount of heat generated by the engine increases as the intake air amount Ga increases. As shown in this figure, the engine room heating amount cther increases as the intake air amount Ga increases. The ECU 40 stores a map that defines the relationship shown in FIG. Here, the engine room heating amount cther corresponding to the current intake air amount Ga is specified based on the map.

  Next, the engine room heating integration amount CTHER is obtained. Here, the engine room heating integration amount CTHER is a value having a correlation with the engine room temperature. Here, the CTHER value calculated in the previous processing cycle is read.

  When the above processing is completed, the engine room max temperature thermax specified in step 208 and the engine room heating integration amount CTHER are compared (step 210). When it is determined that CTHER <thermax is established, it can be determined that the engine room temperature is increasing toward the thermax value. As a result, the heating amount cther obtained in step 208 is added to the engine room heating integrated amount CTHER, and CTHER in this processing cycle is calculated (step 212). Then, it is determined whether or not the CTHER obtained in step 212 exceeds the engine room max temperature thermax (step 214). If CTHER exceeds the thermax value, the calculated CTHER is guarded by the thermax value (step 216).

  On the other hand, if it is determined in step 210 that CTHER <thermax does not hold, it can be determined that the engine room temperature is decreasing toward a certain convergence temperature (here, “intake air temperature tha + α”). . That is, it can be determined that the engine room is being cooled by the influence of heat dissipation or the like. Here, the amount of cooling that the engine room receives is assumed to be the engine room cooling amount cther '. If the above determination is made, the cooling amount cther 'is subtracted from the engine room heating integration amount CTHER, and CTHER in this processing cycle is calculated (step 218). Then, it is determined whether CTHER obtained in step 218 does not fall below the aforementioned temperature (intake air temperature tha + α) (step 220). If CTHER is lower than the intake air temperature tha + α, the calculated CTHER is guarded at the intake air temperature tha + α (step 222).

  Next, an engine room temperature vehicle speed correction coefficient Kspd is calculated based on the vehicle speed (step 224). FIG. 17 shows a map stored in the ECU 40 for calculating the correction coefficient Kspd. In step 224, the correction coefficient Kspd is calculated according to this map. According to this map, the correction coefficient Kspd is set to 1.0 when the vehicle stops at a vehicle speed of 0 km / h, and decreases as the vehicle speed increases.

Next, the engine room estimated temperature ther is calculated according to the following arithmetic expression (step 226).
Estimated engine room temperature ther = CTHER x Kspd (5)

  In the routine shown in FIG. 14, the maximum intake air amount G / N-wot (hereinafter, “G / N-wot (tha, thw, ther)” is then applied so that the influence of the estimated engine room temperature ther is reflected. Is calculated (step 228). Specifically, first, a correction coefficient Kther for reflecting the influence of the estimated engine room temperature ther is calculated.

  FIG. 18 shows a map stored in the ECU 40 for calculating the correction coefficient Kther. In step 228, the correction coefficient Kther is calculated according to this map. According to this map, the correction coefficient Kther is set to 1.0 when the estimated engine room temperature ther is a precondition temperature of the reference G / N-wot characteristic, and is set to a smaller value as the estimated engine room temperature ther increases. The

  In step 228, next, the correction coefficient Kther is multiplied by G / N-wot (tha, thw) calculated in consideration of the effects of the intake air temperature tha and the cooling water temperature thw, and the result is obtained as G / Stored as N-wot (tha, thw, ther). The volumetric efficiency ηv of the intake air increases as the amount of heat received by the intake air decreases. For this reason, the actual maximum intake air amount G / N-wot increases as the engine room estimated temperature ther decreases. According to the correction coefficient Kther described above, the tendency can be correctly reflected in G / N-wot (tha, thw, ther). Therefore, according to the above processing, G / N-wot (tha, thw, ther) that accurately matches the actual maximum intake air amount G / N-wot in consideration of the influence of the estimated engine room temperature ther Can be calculated.

  In the routine shown in FIG. 14, next, the intake air amount G / N per rotation is calculated based on the actually measured value of the intake air amount Ga and the engine speed NE (step 230). Next, the G / N and the G / N-wot (tha, thw, ther) obtained in step 106 are substituted into the above equation (1) to calculate the load factor kload (step 232). G / N-wot (tha, thw, ther) is the actual maximum intake air amount G / N regardless of the intake air temperature tha and the cooling water temperature thw, and the engine room temperature ther. It matches N-wot with high accuracy. For this reason, according to the above processing, it is possible to correctly calculate the load factor kload in accordance with the actual value under any temperature environment.

  Next, the ECU 40 estimates the intake pipe negative pressure PM based on the load factor kload (step 234). Here, specifically, the same processing as step 112 shown in FIG. 6 which is the flowchart of the first embodiment is executed. According to the above processing, the intake pipe negative pressure PM is always accurately estimated regardless of the intake air temperature tha, the warm-up state of the internal combustion engine 32, and the engine room temperature. can do.

  In the third embodiment described above, the effects of the intake air temperature tha, the cooling water temperature thw, and the estimated engine room temperature ther are reflected in the maximum intake air amount G / N-wot, and G / N-wot (tha, Although the load factor kload corresponding to the actual value is obtained based on thw, ther), the calculation procedure is not limited to this. That is, based on the intake air amount G / N and the maximum intake air amount G / N-wot, first, a reference load factor is calculated, and the intake load temperature tha, the cooling water temperature thw, and the estimated engine room temperature are calculated as the reference load factor. Correction for reflecting the influence of ther may be performed to calculate the final load factor kload.

  In the third embodiment described above, the effects of the intake air temperature tha, the cooling water temperature thw, and the estimated engine room temperature ther are reflected in the maximum intake air amount G / N-wot, and G / N-wot (tha, Based on thw, ther), the load factor kload that matches the actual value is obtained, but this combination is not always required. That is, in order to obtain the load factor kload described above, only the influence of the engine room estimated temperature ther may be considered, or the load factor kload may be obtained in combination with other influences such as the cooling water temperature thw. .

  In the above-described third embodiment, the estimated engine room temperature ther is obtained by reflecting the effects of the intake air amount Ga and the vehicle speed. However, the temperature estimation method is not limited to this. . That is, the engine room temperature may be measured by providing a temperature sensor directly in the engine room.

  In the third embodiment described above, the estimated engine room temperature ther corresponds to the “heat reception amount correlation value” in the first invention, and the ECU 40 determines the reference G / N-wot in step 202 described above. By calculating the “maximum intake air amount estimating means” in the first invention, the “heat receiving amount correlation value detecting means” in the first invention is executed in the step 232 by executing the processing of the step 226. By executing the processing, the “load factor calculating means” in the first invention is realized, and by executing the processing in step 234, the “negative pressure correlation value calculating means” in the first invention is realized. Yes.

  In the above-described third embodiment, the ECU 40 executes the process of step 228 so that the “correction means” in the second invention executes the process of step 232 so that the second step is executed. The “calculation means” in the invention is realized respectively.

Embodiment 4 FIG.
[Features of Embodiment 4]
Next, a fourth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 20 to be described later using the hardware configuration shown in FIG.

  In the first to third embodiments described above, the maximum intake air amount G / N-wot that is realistic is calculated by performing correction according to the amount of heat received by the intake air. That is, the volumetric efficiency ηv of the intake air decreases due to heat reception, and as a result, the actual maximum intake air amount G / N-wot becomes a small value. Therefore, the amount of heat received by the intake air is estimated from the intake air temperature tha, the cooling water temperature thw, and the estimated engine room temperature ther, and the influence of the heat reception is reflected on the load factor kload, so that the correct intake pipe negative pressure PM can be estimated.

  In the meantime, in the correction means, the amount of heat received by the intake air is estimated based on the heat reception amount correlation value, but in order to more accurately estimate the amount of heat received by the intake air, Can be considered.

  FIG. 19 is a diagram for explaining the dependency of the intake air temperature increase amount on the intake air amount Ga. Here, the intake air temperature rise is a value having a correlation with the amount of heat received by the intake air from the cooling water temperature thw or the estimated engine room temperature ther. The solid line shown in FIG. 19 shows the relationship between the intake air amount Ga and the intake air temperature increase amount in the situation where the cooling water temperature thw is 90 ° C., and the broken line shows the situation in which the cooling water temperature thw is 40 ° C. The relations established are shown in These relationships show that the intake air temperature rise amount tends to decrease as the intake air amount Ga increases, regardless of the level of the coolant temperature thw, that is, the warm-up state of the internal combustion engine. This is because the greater the intake air amount Ga, the higher the flow rate of the intake air, and thus the shorter the heat reception time, resulting in a decrease in the heat reception amount. Even if the amount of heat received is the same, the amount of increase in intake air temperature decreases as the amount of intake air Ga increases.

  Therefore, in the present embodiment, in addition to the corrections shown in the first to third embodiments, the influence of the intake air amount Ga on the amount of heat received by the intake air is reflected in the maximum intake air amount G / N-wot. The load factor kload that takes into account the effect of the heat received by the intake air that does not appear in the received heat amount correlation value is calculated, and based on the load factor kload, the intake pipe negative pressure PM in accordance with the actual value is estimated. .

[Specific Processing in Embodiment 4]
FIG. 20 is a flowchart of a routine executed by the ECU 40 to estimate the intake pipe negative pressure PM. Steps 300 to 310 shown in this flowchart are the same as steps 200 to 210 shown in FIG. In the present embodiment, following step 310, the intake air amount Ga is taken in (step 312). Next, a maximum intake air amount G / N-wot (hereinafter referred to as “G / N-wot (Ga)”) is calculated so as to reflect the influence of the intake air amount Ga (step 314). Specifically, first, a correction coefficient Kga for reflecting the influence of the intake air amount Ga is calculated.

  FIG. 21 shows a map stored in the ECU 40 for calculating the correction coefficient Kga. In step 314, the correction coefficient Kga is calculated according to this map. According to this map, the correction coefficient Kga is 1.0 at the value of the intake air amount Ga corresponding to the engine speed NE equivalent to 5000 (rpm), and is set to a larger value as the intake air amount Ga is lower.

  In step 314, G / N-wot (tha, thw, ther) calculated by taking into account the effects of the intake air temperature tha, the coolant temperature thw, and the estimated engine room temperature ther is multiplied by the correction coefficient Kga. The result is stored as G / N-wot (Ga). The volumetric efficiency ηv of the intake air increases as the amount of heat received by the intake air decreases. For this reason, the actual maximum intake air amount G / N-wot becomes smaller as the intake air amount Ga is lower. According to the correction coefficient Kga described above, the tendency can be correctly reflected in G / N-wot (Ga). Therefore, according to the above processing, it is possible to calculate G / N-wot (Ga) that accurately matches the actual maximum intake air amount G / N-wot in consideration of the influence of the intake air amount Ga. it can.

  In the routine shown in FIG. 20, next, the intake air amount G / N per rotation is calculated based on the actually measured value of the intake air amount Ga and the engine speed NE (step 316). Next, the G / N and the G / N-wot (Ga) obtained in the above step 314 are substituted into the above equation (1) to calculate the load factor kload (step 318). G / N-wot (Ga) accurately matches the actual maximum intake air amount G / N-wot regardless of the value of the intake air amount Ga. For this reason, according to the above processing, it is possible to correctly calculate the load factor kload in accordance with the actual value under any temperature environment.

  Next, the ECU 40 estimates the intake pipe negative pressure PM based on the load factor kload (step 320). Here, specifically, the same processing as step 112 shown in FIG. 6 which is the flowchart of the first embodiment is executed. According to the above processing, regardless of the intake air temperature tha, regardless of the warm-up state of the internal combustion engine 32, regardless of the engine room temperature, and regardless of the amount of intake air Ga, The intake pipe negative pressure PM can always be accurately estimated.

  By the way, in the fourth embodiment described above, the effects of the intake air temperature tha, the cooling water temperature thw, the estimated engine room temperature ther, and the intake air amount Ga are reflected in the maximum intake air amount G / N-wot. Although the load factor kload corresponding to the actual value is obtained based on wot (Ga), the calculation procedure is not limited to this. That is, based on the intake air amount G / N and the maximum intake air amount G / N-wot, first, a reference load factor is calculated, and the reference load factor includes the intake air temperature tha, the cooling water temperature thw, the engine room estimated temperature ther Alternatively, the final load factor kload may be calculated by performing correction for reflecting the influence of the intake air amount Ga.

  In the fourth embodiment described above, the effects of the intake air temperature tha, the cooling water temperature thw, the estimated engine room temperature ther, and the intake air amount Ga are reflected in the maximum intake air amount G / N-wot. Although the load factor kload corresponding to the actual value is obtained based on wot (Ga), this combination is not always required. That is, in order to obtain the load factor kload described above, only the influence of the intake air amount Ga may be considered, or the load factor kload may be obtained in combination with other influences such as the cooling water temperature thw.

  In the fourth embodiment described above, the ECU 40 calculates the reference G / N-wot in step 302, whereby the “maximum intake air amount estimating means” in the tenth to thirteenth inventions is the same as in step 318. The “load factor calculating means” in the tenth to thirteenth inventions by executing the process of step 10 and the “negative pressure correlation value calculating means” in the tenth to thirteenth inventions by executing the process of step 320 above. , Each has been realized.

  Further, in the above-described fourth embodiment, the ECU 40 corrects the intake air amount per one rotation of the internal combustion engine based on the intake air amount in the above step 314, so that “correction means” in the tenth aspect of the invention is achieved. ”Is corrected based on the intake air amount, so that the“ correction means ”in the eleventh aspect of the invention corrects the load factor based on the intake air amount. The “correction means” according to the present invention is realized by correcting the negative pressure correlation value based on the intake air amount, thereby realizing the “correction means” according to the thirteenth aspect of the present invention.

  In the above-described fourth embodiment, the ECU 40 performs the correction in step 314 so as to eliminate the influence due to the change in the maximum intake air amount, whereby the “correction means” in the fourteenth aspect of the invention is It has been realized.

Embodiment 5. FIG.
[Features of Embodiment 5]
Next, a fifth embodiment of the present invention will be described with reference to FIGS. The system of the present embodiment can be realized by causing the ECU 40 to execute a routine shown in FIG. 22 to be described later, using the hardware configuration shown in FIG.

  In the first to third embodiments described above, the load factor kload is calculated by dividing the intake air amount G / N by the maximum intake air amount G / N-wot. Also, since the actual maximum intake air amount G / N-wot varies depending on the change in the volumetric efficiency ηv of the intake air according to the amount of heat received, the intake air temperature tha, the coolant temperature thw, and the estimated engine room temperature ther By reflecting the influence of the amount of heat received by the intake air on the load factor kload, it is possible to correctly estimate the intake pipe negative pressure PM.

  As described above, the intake air amount G / N is based on the intake air amount Ga (g / sec) measured by the air flow meter 26 and the engine rotational speed NE (rpm) detected by the rotational speed sensor 38. Is calculated. Therefore, if the volumetric efficiency ηv of the intake air does not change after passing through the air flow meter, the load factor kload can be accurately calculated by using the intake air amount G / N obtained by the above method.

  However, the volumetric efficiency ηv of the air sucked into the intake passage 18 changes according to the amount of heat received. That is, the volumetric efficiency ηv of the intake air decreases as the amount of heat received by the intake air increases. Therefore, as the amount of heat received by the intake air increases, the volume efficiency ηv decreases, and the actual intake pipe negative pressure PM becomes a negative pressure value (a value close to atmospheric pressure) lower than the estimated value. Therefore, the intake pipe negative pressure PM cannot be correctly estimated under a situation where the volumetric efficiency ηv of the intake air amount G / N changes.

  Further, as described above, the intake air amount Ga affects the amount of heat received by the intake air. That is, the amount of increase in intake air temperature tends to decrease as the intake air amount Ga increases. For this reason, the volumetric efficiency ηv of the intake air becomes lower as the intake air amount Ga becomes smaller, and the actual intake pipe negative pressure PM becomes a lower negative pressure value (a value close to the atmospheric pressure) than the estimated value, as described above. .

  Therefore, in the present embodiment, in order to correct the change in the volumetric efficiency ηv of the intake air after passing through the air flow meter, the influence of heat reception from the cooling water temperature thw or the estimated engine room temperature ther, and the intake air amount Ga are received. By further considering the influence on the heat quantity on the intake pipe negative pressure PM estimated in the third embodiment, the intake pipe pressure PM in accordance with the actual value is estimated.

[Specific Processing in Embodiment 5]
FIG. 22 is a flowchart of a routine that the ECU 40 executes to estimate the intake pipe negative pressure PM. In this routine, first, the intake pipe negative pressure PM is estimated based on the load factor kload (step 400). Hereinafter, for the sake of convenience, the estimated intake pipe negative pressure PM is referred to as “reference intake pipe negative pressure PM (0)”. Specifically, in step 400, processing similar to that in steps 200 to 234 shown in FIG. 13 which is the flowchart of the third embodiment is executed.

  Next, the cooling water temperature thw is taken in (step 402). Next, an intake pipe negative pressure correction coefficient Kthwpm for reflecting the influence of the coolant temperature thw is calculated.

  FIG. 23 shows a map stored in the ECU 40 for calculating the correction coefficient Kthwpm. In step 402, the correction coefficient Kthwpm is calculated according to this map. According to this map, the correction coefficient Kthwpm approaches 1.0 as the cooling water temperature thw decreases, and decreases as the cooling water temperature thw increases.

  As will be described later, the correction coefficient Kthwpm is a value multiplied by the reference intake pipe negative pressure PM (0). According to the above processing, the higher the cooling water temperature thw, that is, the lower the volumetric efficiency ηv of the intake air (the more the intake air expands), the lower the reference intake pipe negative pressure PM (0) to a lower negative pressure value (more Can be corrected).

  Next, the estimated engine room temperature ther is captured (step 404). Next, an intake pipe negative pressure correction coefficient Ktherpm for reflecting the influence of the estimated engine room temperature ther is calculated.

  FIG. 24 shows a map stored in the ECU 40 for calculating the correction coefficient Ktherpm. In step 404, the correction coefficient Ktherpm is calculated according to this map. According to this map, the correction coefficient Ktherpm approaches 1.0 as the engine room estimated temperature ther decreases, and decreases as the engine room estimated temperature ther increases.

  As will be described later, the correction coefficient Ktherpm is a value multiplied by the reference intake pipe negative pressure PM (0). According to the above processing, the reference intake pipe negative pressure PM (0) is reduced to a lower negative pressure value as the estimated engine room temperature ther is higher, that is, as the volumetric efficiency ηv of the intake air is decreased (as the intake air is expanded) ( Correction to a value closer to atmospheric pressure).

Next, the intake air amount Ga is taken in (step 406). Next, an intake pipe negative pressure correction coefficient Kgapm for reflecting the influence of the intake air amount Ga is calculated.

  FIG. 25 shows a map stored in the ECU 40 for calculating the correction coefficient Kgapm. In step 406, the correction coefficient Kgapm is calculated according to this map. According to this map, the correction coefficient Kgapm approaches 1.0 as the intake air amount Ga increases, and decreases as the intake air amount Ga decreases.

  As will be described later, the correction coefficient Kgapm is a value multiplied by the reference intake pipe negative pressure PM (0). According to the above processing, the lower the intake air amount Ga, that is, the lower the volumetric efficiency ηv of the intake air (the more the intake air expands), the lower the reference intake pipe negative pressure PM (0) to a lower negative pressure value (more Can be corrected to a value close to atmospheric pressure).

  Next, the reference intake pipe negative pressure PM (0) is multiplied by correction coefficients Kthwpm, Ktherpm, and Kgapm, and the result is estimated as PM. (Step 408). Therefore, according to the above processing, the intake pipe negative pressure PM can be accurately estimated in consideration of the influence of the change in the volumetric efficiency ηv in the intake pipe.

  When the above process is completed, the intake pipe negative pressure PM calculated in step 408 is compared with the reference intake pipe negative pressure PM (0). (Step 410). If it is determined in step 410 that PM (0)> PM is established, the intake pipe negative pressure PM is guarded by the value of PM (0) (step 412).

  In the fifth embodiment described above, the change in the volumetric efficiency ηv inside the intake pipe due to the effects of the cooling water temperature thw, the estimated engine room temperature ther, and the intake air amount Ga is determined based on the reference intake pipe negative pressure PM (0). However, the calculation procedure is not limited to this. That is, the reference load factor calculated based on the intake air amount G / N and the maximum intake air amount G / N-wot includes the cooling water temperature thw, the estimated engine room temperature ther, or the intake air amount Ga in the intake pipe. The final load factor kload may be calculated by reflecting the influence on the change in the internal volumetric efficiency ηv. Further, the final load factor kload may be calculated by correcting the intake air amount G / N to reflect the above effect.

  Further, in the fifth embodiment described above, the change in the volumetric efficiency ηv inside the intake pipe due to the effects of the cooling water temperature thw, the estimated engine room temperature ther, and the intake air amount Ga is used as the reference intake pipe negative pressure PM (0). The intake pipe negative pressure PM that matches the actual value is obtained, but this combination is not always required. That is, in order to obtain the intake pipe negative pressure PM described above, only the influence of the engine room estimated temperature ther may be considered, or in combination with other influences such as the cooling water temperature thw, the final intake pipe negative pressure PM may be considered. It is good also as obtaining pressure PM.

  In the above-described fifth embodiment, the reference intake pipe negative pressure PM (0) is used in step 400, but the intake pipe negative pressure to be used is not limited to this. The reference intake pipe negative pressure PM (0) is an estimated value reflecting a change in volumetric efficiency ηv inside the intake pipe due to heat reception in the maximum intake air amount G / N-wot. That is, the reference intake pipe negative pressure PM (0) in step 400 may be replaced with the intake pipe negative pressure PM estimated from the reference load factor that does not consider the influence of the maximum intake air amount G / N-wot due to the heat reception. .

  In the fifth embodiment described above, the ECU 40 executes the process of step 400, so that the “negative pressure correlation value calculating means” in the sixth aspect of the invention executes the process of step 408. The “correction means” in the sixth aspect of the invention is realized.

  Further, in the above-described fifth embodiment, the ECU 40 corrects the intake air amount per one rotation of the internal combustion engine based on the intake air amount in the above steps 400 to 412, thereby correcting the “correction” in the tenth invention. The “means” corrects the maximum intake air amount based on the intake air amount, and the “correction means” in the eleventh aspect corrects the load factor based on the intake air amount. The “correction means” in the thirteenth aspect of the present invention is realized by the “correction means” in the invention correcting the negative pressure correlation value based on the intake air amount.

  In the fifth embodiment described above, the ECU 40 performs the correction in step 400 to 412 so as to eliminate the influence of the change in the intake air amount per one rotation of the internal combustion engine, whereby the fifteenth invention. The “correction means” in FIG.

It is a figure for demonstrating the structure of Embodiment 1 of this invention. It is a figure which shows the relationship between the load factor kload of an internal combustion engine, and intake pipe negative pressure PM. It is a figure for demonstrating the dependence with respect to the intake temperature tha of the largest intake air amount G / N-wot. It is a figure for demonstrating the dependence with respect to the cooling water temperature thw of the largest intake air amount G / N-wot. It is the figure which represented the relationship formed between the reference | standard load factor and the intake pipe negative pressure PM in contrast with the case where the cooling water temperature thw is 90 degreeC, and 20 degreeC. It is a flowchart of the routine performed in order to estimate the load factor kload in Embodiment 1 of this invention. It is a map of the correction coefficient Ka for reflecting the influence of the intake air temperature tha on the reference load factor. It is a map of the correction coefficient Kw for reflecting the influence of the cooling water temperature thw on the reference load factor. It is a flowchart of the routine performed as a part of purge control in Embodiment 1 of this invention. 6 is a map of a maximum purge flow rate Pmax in which the intake pipe pressure PM is set as a parameter. It is a flowchart of the routine performed in Embodiment 2 of this invention. It is a figure for demonstrating the content of step 138 shown in FIG. 11 concretely. It is a figure for demonstrating the dependence with respect to the intake air amount Ga of engine room estimated temperature ther. It is a flowchart of the routine performed in Embodiment 3 of the present invention. 6 is a map for determining an engine room max temperature thermax from an intake air amount Ga. 6 is a map for obtaining an engine room heating amount cther from an intake air amount Ga. It is a map of the correction coefficient Kspd for reflecting the influence of the vehicle speed on the engine room estimated temperature ther. It is a map of the correction coefficient Kther for reflecting the influence of the engine room estimated temperature ther on the reference load factor. It is a figure for demonstrating the dependence with respect to the intake air amount Ga of the intake air temperature rise amount. It is a flowchart of the routine performed in Embodiment 4 of this invention. It is a map of the correction coefficient Kga for reflecting the influence of the intake air amount Ga on the reference load factor. It is a flowchart of the routine performed in Embodiment 5 of this invention. It is a map of the correction coefficient Kthwpm for reflecting the influence of the cooling water temperature thw on the reference intake pipe negative pressure. It is a map of the correction coefficient Ktherpm for reflecting the influence of the engine room estimated temperature ther on the reference intake pipe negative pressure. It is a map of the correction coefficient Kgapm for reflecting the influence of the intake air amount Ga on the reference intake pipe negative pressure.

Explanation of symbols

10 Canister 22 Purge VSV
18 Intake passage 26 Air flow meter 28 Intake temperature sensor 32 Internal combustion engine 36 Water temperature sensor 40 ECU (Electronic Control Unit)
tha intake air temperature
thw cooling water temperature
kload load factor
Ga intake air volume
NE engine speed
G / N Intake air volume per rotation
G / N-wot Maximum intake air volume per rotation
Pmax Maximum purge flow
PM Intake pipe negative pressure

Claims (15)

A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
A received heat amount correlation value detecting means for detecting a received heat amount correlation value correlated with the received heat amount of the intake air;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount, the maximum intake air amount, and the heat reception amount correlation value;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The load factor calculation means is configured such that the smaller the heat reception amount correlation value, the smaller the load factor relative to a reference load factor obtained by dividing the intake air amount by the maximum intake air amount. An intake pipe negative pressure correlation value estimation system characterized by calculating. The maximum intake air amount estimation means estimates the maximum intake air amount on the assumption that the heat reception amount correlation value is a reference value,
The load factor calculating means includes
Correction means for correcting the maximum intake air amount to a larger value as the heat reception amount correlation value is smaller;
The intake pipe negative pressure correlation value estimation system according to claim 1, further comprising a calculation unit that calculates the load factor by dividing the intake air amount by the corrected maximum intake air amount.   The intake pipe negative pressure correlation value estimation system according to claim 1 or 2, wherein the intake pipe negative pressure correlation value is an intake pipe negative pressure itself of an internal combustion engine. A canister for adsorbing and holding evaporated fuel;
A purge passage for conducting the canister to the intake passage;
A purge control valve for controlling a conduction state of the purge passage;
Maximum purge flow rate estimating means for estimating a maximum purge flow rate obtained by fully opening the purge control valve based on the intake pipe negative pressure;
A target opening setting means for setting a target opening of the purge control valve based on a ratio between a required purge flow rate and the maximum purge flow rate;
The intake pipe negative pressure correlation value estimation system according to claim 3, further comprising: The load factor calculating means includes
Correction means for correcting the intake air amount to a larger value as the heat reception amount correlation value is larger;
The intake pipe negative pressure correlation value estimation system according to claim 1, further comprising a calculation unit that calculates the load factor by dividing the corrected intake air amount by the maximum intake air amount. The load factor calculating means calculates the load factor so as to eliminate the influence of the heat reception amount correlation value on the maximum intake air amount;
The negative pressure correlation value calculation means further comprises correction means for correcting the heat reception amount correlation value so as to eliminate the influence on the intake air amount,
The intake pipe negative pressure correlation value estimation system according to claim 1, wherein the correction means corrects the negative pressure correlation value to a lower negative pressure value as the heat receiving amount correlation value is larger. A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
A received heat amount correlation value detecting means for detecting a received heat amount correlation value correlated with the received heat amount of the intake air;
Reference load factor calculating means for obtaining a reference load factor of the internal combustion engine by dividing the intake air amount by the maximum intake air amount;
A relationship setting means for setting a relationship between the reference load factor and the intake pipe negative pressure correlation value based on the heat reception amount correlation value;
Negative pressure correlation value calculating means for calculating an intake pipe negative pressure correlation value corresponding to the reference load factor based on the relationship;
An intake pipe negative pressure correlation value estimation system comprising: The maximum intake air amount estimation means estimates the maximum intake air amount on the assumption that the heat reception amount correlation value is a reference value,
The relationship setting means sets the relationship between the two so that the intake pipe negative pressure correlation value corresponding to the reference load factor becomes larger as the heat reception amount correlation value is smaller. Item 8. The intake pipe negative pressure correlation value estimation system according to Item 7. A canister for adsorbing and holding evaporated fuel;
A purge passage for conducting the canister to the intake passage;
A purge control valve for controlling a conduction state of the purge passage,
The intake pipe negative pressure correlation value is a maximum purge flow rate obtained by fully opening the purge control valve,
The intake pipe negative pressure correlation value according to claim 8, further comprising target opening setting means for setting a target opening of the purge control valve based on a ratio between a required purge flow rate and the maximum purge flow rate. Estimation system. A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Correction means for correcting the intake air amount per rotation of the internal combustion engine calculated based on the intake air amount based on the intake air amount;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the corrected intake air amount and the maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The correction means includes
The intake pipe negative pressure correlation value estimation system, wherein the corrected intake air amount is calculated as a larger value as the intake air amount is smaller. A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Correction means for correcting the maximum intake air amount based on the intake air amount;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the corrected maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor,
The correction means includes
The intake pipe negative pressure correlation value estimation system, wherein the corrected maximum intake air amount is calculated as a smaller value as the intake air amount is smaller. A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the maximum intake air amount;
Correction means for correcting the load factor based on the intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the corrected load factor,
The correction means includes
The intake pipe negative pressure correlation value estimation system, wherein the corrected load factor is calculated as a larger value as the intake air amount is smaller. A system for estimating an intake pipe negative pressure correlation value correlated with an intake pipe negative pressure of an internal combustion engine,
An air flow meter for detecting the amount of intake air;
Maximum intake air amount estimating means for estimating the maximum intake air amount generated when the throttle valve is fully opened based on the engine speed;
Load factor calculating means for calculating a load factor of the internal combustion engine based on the intake air amount and the corrected maximum intake air amount;
Negative pressure correlation value calculating means for calculating the intake pipe negative pressure correlation value based on the load factor;
Correcting means for correcting the negative pressure correlation value based on the intake air amount;
The correction means includes
The intake pipe negative pressure correlation value estimation system, wherein the corrected negative pressure correlation value is calculated as a lower negative pressure value as the intake air amount is smaller.   14. The correction unit according to claim 10, wherein the correction unit performs correction so as to eliminate a change in the intake pipe negative pressure correlation value due to a change in the maximum intake air amount caused by the intake air amount. Intake pipe negative pressure correlation value estimation system.   The correction means corrects so as to exclude a change in the intake pipe negative pressure correlation value due to a change in the intake air amount per one rotation of the internal combustion engine due to the intake air amount. 14. The intake pipe negative pressure correlation value estimation system according to 10 to 13.

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