JPH07139365A - High load judgement equipment of internal combustion engine - Google Patents

Abstract

PURPOSE:To enhance responding capability on supercharging and quickly prevent knocking by instantaneously conducting high load judgement with a high load control means independent of a specified time when supercharging pressure exceeds a set value on supercharging. CONSTITUTION:A supercharging pressure detecting means which detects supercharging pressure PB and an intercooler water temperature detecting means 25 which detects water temperature TWIC of an intercooler cooling water line are installed. A first high-load judgement means which judges as a high-load condition when the supercharging pressure PB detected by the supercharging pressure detecting means exceeds a first set value PBWOT1 and keeps its state for a specified time tmWOT is installed. A second high-load judgement means which judges as a high-load condition independent of a specified time tmWOT when the supercharging pressure PB detected by the supercharging pressure detecting means exceeds a second set value PBWOT2 which is higher than the first set value when the water temperature of the intercooler cooling water line is at normal temperature is installed. A changing means which changes the second set value PBWOT2 according to the intercooler water temperature TWIC is installed. Thereby, knocking is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high load judging device for an internal combustion engine equipped with a supercharger.

[0002]

2. Description of the Related Art A technique relating to an internal combustion engine equipped with a supercharger is described in Japanese Patent Application Laid-Open No. 4-175422. In the case of an internal combustion engine equipped with a supercharger, since a considerably high load state occurs during supercharging and knocking is likely to occur, a method is used in advance to determine from a supercharging pressure that the engine is in a high load state where knocking easily occurs. ing.

In the conventional high load judgment, a delay of a fixed time is provided to prevent the judgment from being mistaken due to a temporary overshoot of boost pressure or noise during a transient period.
When the boost pressure exceeds a predetermined value and continues for a certain period of time, it is determined that the load is high.

[0004]

[Problems to be solved] However, even if the load is considerably high, the high load is not judged until a certain period of time elapses. Therefore, in an internal combustion engine equipped with a supercharger, it is necessary to cope with the delay. However, there is a problem that delay knocking occurs. Especially when there is a deviation in the throttle opening sensor, the high load judgment is delayed, and knocking is likely to occur.

The present invention has been made in view of the above points, and the object of the present invention is to accurately and early make a high load judgment, promptly take knocking prevention measures, and improve responsiveness at the time of supercharging. The point is to provide a boost pressure control device.

[0006]

To achieve the above object, the first aspect of the present invention is directed to a supercharging pressure detecting means for detecting supercharging pressure in an internal combustion engine equipped with a supercharger and an intercooler. And an intercooler water temperature detecting means for detecting the water temperature of the intercooler cooling water circuit, and a state in which the supercharging pressure detected by the supercharging pressure detecting means exceeds a first predetermined value for a predetermined time. The first high load determining means for determining a high load state and the supercharging pressure detected by the supercharging pressure detecting means are higher than the first predetermined value when the water temperature of the intercooler cooling water circuit is a normal temperature. When the second predetermined value is exceeded, a second high load determination means for determining a high load state regardless of the predetermined time, and the second high load determination means according to the intercooler water temperature detected by the intercooler water temperature detection means. Change the specified value And high load determination device for an internal combustion engine, characterized in that a further means.

The first high load judging means judges that the supercharging pressure is high when the supercharging pressure exceeds the first predetermined value and continues for a predetermined time, but the supercharging pressure is usually lower than the first predetermined value when supercharging. When the high second predetermined value is exceeded, the second high load determination means can immediately make a high load determination regardless of the predetermined time, improve responsiveness at the time of supercharging, and promptly take knocking prevention measures. The second predetermined value can be changed by the changing means to an appropriate value in accordance with the intercooler water temperature, and a high load operating state where knocking easily occurs can be quickly judged to prevent knocking more appropriately. Measures can be taken.

According to the second aspect of the invention, the second predetermined value is changed to an appropriate value in accordance with the rate of change of the supercharging pressure, so that the high load operating state where knocking is likely to occur at the time of supercharging can be speeded up. Therefore, it is possible to more appropriately take knocking prevention measures.

[0009]

EXAMPLE An example of the present invention shown in FIGS. 1 and 2 will be described below. FIG. 1 is a configuration diagram of an intake control system of an internal combustion engine of this embodiment.

An intake passage 1 and an exhaust passage 2 are connected to the engine body E, and a mechanical supercharger SC, an intercooler IC and a throttle valve are sequentially provided in the intake passage 1 from an air cleaner A at an upstream end thereof to a downstream side. 4 is installed. A bypass passage 3 that bypasses the mechanical supercharger SC and the intercooler IC is connected to the intake passage 1, and a bypass valve 5 is provided in the bypass passage 3.

A control chamber 6 for changing the internal compression ratio is integrally attached to the mechanical supercharger SC, and a conduit 7 is provided from the control chamber 6.
Are extended and connected to the electromagnetic switching valve 8. On the other hand, a conduit 9 branches off from a junction with the bypass passage 3 of the intercooler IC and is connected to the electromagnetic switching valve 8.

The electromagnetic switching valve 8 is connected to a conduit 9 as well as a passage 11 communicating with the atmosphere via an air cleaner 10.
The state in which the atmospheric pressure is introduced from the air cleaner 10 via the passage 11 and the state in which the supercharging pressure in the intake passage 1 is introduced via the conduit 9 is switched to the conduit 7 leading to the control chamber 6 of the mechanical supercharger SC. be able to.

When the atmosphere is introduced into the control room 6, the mechanical supercharger SC has a low compression ratio, and when the supercharging pressure is introduced, the mechanical supercharger SC has a high compression ratio. By-pass valve driving means for switching the electromagnetic switching valve 8 and opening / closing the bypass valve 5.
The operation of 12 is controlled by the control means C including a microcomputer.

The control means C receives detection signals from various sensors for judging the operating state of the engine.

First, the engine body E is provided with an engine speed sensor 20 along the crankshaft 13, which detects the engine speed N _E and sends a detection signal to the control means C to open a throttle opening provided on the throttle valve 4. The degree sensor 21 sends a detection signal of the throttle opening θ _{TH to} the control means C, and the bypass opening sensor 22 provided in the bypass valve 5 sends a detection signal of the bypass opening θ _{BP to} the control means C. To be

A supercharging pressure sensor 19 is provided downstream of the throttle valve 4 in the intake passage 1 to detect the supercharging pressure P _B and send it to the control means C.

The intercooler IC is provided with a cooling water channel 26 independent of the engine cooling water channel.
The electric water pump 27 and the radiator 28 controlled by the control means C are provided between the intercooler IC and the radiator 28, and the cooling water is circulated between the intercooler IC and the radiator 28. The sensor 25 detects the water temperature of this circulating cooling water on the outlet side from the intercooler IC.

Further, the engine water temperature T _W for cooling the engine body E
An engine water temperature sensor 23 for detecting the above is arranged in the engine cooling water passage, and its detection signal is inputted to the control means C.

The control means C controls the engine speed N _E , the throttle opening θ _TH , the boost pressure P _B and the bypass opening θ _BP.
Further, the intercooler water temperature T _WIC or the like is input and processed to operate the electromagnetic switching valve 8 and the bypass valve drive means 12 to perform supercharging pressure control.

The internal combustion engine in which such supercharging pressure control is performed is
As knocking may occur under high load,
It is necessary to promptly take measures to prevent the occurrence of knocking by quickly discriminating a high load state in which knocking easily occurs. The high load determination processing control will be described with reference to the flowchart of FIG.

First, in step 1, a high fuel load increase coefficient K is obtained by a map search from the engine speed N _E and the boost pressure P _B.
WOT is selected, and in the next step 2, the first boost pressure
The high load determination value P _BWOT1 and the second high load determination value P _BWOT2 for supercharging pressure are separately determined in step 3 from the intercooler water temperature T _{WIC and the} like.

FIG. 3 is a graph showing the values of the first high load judgment value P _BWOT1 and the second high load judgment value P _BWOT2 of the predetermined supercharging pressure with respect to the intercooler water temperature T _WIC . As shown, the first high load determination value P _BWOT1 maintains a constant value, but the second high load determination value P _BWOT2 is _lower than the first high load determination value P _BWOT1 when the intercooler water temperature T _WIC is in the normal temperature state. A value higher by a predetermined value is decided,
Intercooler water temperature T _{WI C} with certain temperature A ₁ (eg 60
℃) or more, the temperature gradually decreases to the temperature B ₁ (eg 90
(° C), it becomes the same value as the first high load judgment value P _{BWOT1. If the} abnormal high temperature state is higher than the temperature B after the transition state during this period, a value lower than the first high load judgment value P _BWOT1 is determined.

That is, the second high load judgment value P _BWOT2 is gradually set low as the intercooler water temperature T _WIC exceeds the normal temperature state and becomes a transition state higher than the temperature A _{1 and an} abnormal high temperature state higher than the temperature B _1. , The high-load judgment is performed more promptly and appropriate knocking prevention measures are taken.

Next, in step 4, it is judged whether or not the throttle opening sensor 21 is abnormal.
If it is not abnormal, the _routine proceeds to step 5, where the full-open throttle opening judgment value θ _WOT is obtained by a table search based on the engine speed N _E, and at the next step 6, the actual throttle opening θ _TH is the throttle opening. Compared with the judgment value θ _WOT , if the throttle opening θ _TH exceeds the throttle opening judgment value θ _WOT , it means that it is fully opened and the high load judgment processing is performed, but if θ _TH <θ _WOT Proceeds to step 7.

In step 7, it is judged whether or not there is an abnormality in other sensors such as the supercharging pressure sensor 19, and if there is an abnormality, the process jumps to step 23. If there is no abnormality, the process proceeds to step 8 and the engine speed N _E It is determined whether or not the _engine speed is lower than the predetermined _engine speed N _{EWOTO. If the engine} speed is low, the process jumps to step 23. If the engine speed is not low, the process proceeds to step 9, and this time the engine water temperature T _W.
Is higher than the predetermined temperature T _WWOTE , and if it is higher, the process jumps to step 23, and if not higher, the process proceeds to step 10.

That is, there is an abnormality in another sensor,
If the engine speed N _E is low or the engine water temperature T _W is high, the process skips to step 23 and the delay determination by the timer described later is not performed, but otherwise the process proceeds to step 10.

At step 10, the first high load judgment value P _BWOT1
And the second high load judgment value P _BWOT2 are compared,
If P _BWOT1 ≤ P _BWOT2 , proceed to step 11
_{If BWOT1} > P _BWOT2 , proceed to step 19.

When P _BWOT1 ≤ P _BWOT2 and the _{routine proceeds} to step 11, it is judged whether or not the supercharging pressure P _B is larger than the first high load judgment value P _BWOT1 determined in step 2, and when initially low load Advances to step 12 and searches for the first predetermined time tmWOT1 and the second predetermined time tmWOT2.

The first predetermined time tmWOT1 is determined by the change rate ΔP _B of the supercharging pressure, and FIG. 4 is a graph showing the value of the first predetermined time tmWOT1 with respect to the change rate ΔP _B. When ΔP _B is small, tmWOT1 is large, and there is a certain ΔP
_It gradually decreases from the value of _B and finally becomes 0.

On the other hand, the second predetermined time tmWOT2 is determined by the intercooler water temperature T _WIC , and FIG. 5 is a graph showing the value of the second predetermined time tmWOT2 with respect to the intercooler water temperature T _WIC . TmWO when _WIC is small
T2 is large and gradually decreases from a certain value of T _WIC to finally 0.

As described above, when the change rate ΔP _{B of the} supercharging pressure and the intercooler water temperature T _WIC are respectively above a certain value, the first predetermined time tmWOT1 and the second time which are delay times when the high load judgment is made Trying to deal with knocking properly by setting tmWOT2 short for a predetermined time to make a quick decision.

In this way, the first predetermined time tmWOT1 and the second predetermined time tmWOT2 are searched, and in the next step 13, both are compared. When tmWOT1> tmWOT2, the process proceeds to step 15 and is actually used. Set the smaller tmWOT2 as the timer time tmWOT. Conversely, if tmWOT1 ≤ tmWOT2, proceed to step 14 to adopt the smaller tmWOT1 and set the timer time.
Set to tmWOT.

At step 16, the high load determination flag F _{WOT is set} to "0" and the high load increase coefficient K _{WOT is set} to 1.0 (step 17). It is determined that the load is not high and the fuel amount is not increased. I am trying.

When P _BWOT1 ≤ P _BWOT2 , step
When it is determined in 11 that the supercharging pressure P _B has _exceeded the first high load determination value P _BWOT1 , the process proceeds to step 18, and it is determined whether or not the timer time tmWOT set in step 14 or step 15 has become 0, Until it reaches 0, go to step 19
The second high load determination value P _{BWOT2 having a} value larger than the high load determination value P _BWOT1 and the supercharging pressure P _B are compared, and the supercharging pressure P _B is _lower than the second high load determination value P _BWOT2. If (P _BWOT1 <P _B <P _BWOT2 ), then step 16
And proceed to F _WOT = 0 and K _WOT = 1.0 (step 1
7) keep.

When the timer tmWOT becomes 0 in the state of P _BWOT1 <P _B <P _BWOT2 , step 18 to step 20
And the high load is determined (F _WOT = 1) in the subsequent route from step 20 (step 22 or step 30).

If the supercharging pressure P _B may exceed the second high load judgment value P _BWOT2 even before the timer tmWOT becomes 0, the process proceeds from step 19 to step 20, and the subsequent step 22 or Judgment of high load in step 30 (F
_WOT = 1) is done.

In any case, in step 20, which is the starting point of the route where the high load is determined, the high load increase coefficient K _WOT retrieved in step 1 is compared with the separately determined low water temperature increase coefficient K _TW2. The larger one is used to increase the fuel amount.

That is, when the intercooler water temperature T _WIC is not so high and P _BWOT1 ≤ P _BWOT2 , when the supercharging pressure P _B increases due to supercharging, the first high load determination value P
_{Even if} it exceeds _BWOT1 , it is not judged as a high load until the timer time tmWOT set in step 14 or step 15 is up, and the effect of temporary overshoot is avoided.

However, even before the timer time tmWOT expires, the boost pressure P _B remains at the second high load determination value P.
_{If BWOT2} is exceeded in some cases, the high load determination flag F _WOT is immediately set to "1" to determine that the load is high, the amount of fuel is increased, and the air-fuel ratio is changed to prevent the occurrence of knocking. .

Even if the throttle opening sensor 21 is misaligned and the load is high during supercharging, the high load cannot be determined in step 6 and the process proceeds to step 7 to quickly determine the high load state. The amount of fuel is increased to prevent knocking.

On the other hand, the intercooler water temperature T _WIC becomes high, and the first high load judgment value P _BWOT1 and the second high load judgment value P _BWOT2
When P _BWOT1 > P _BWOT2 is reversed, the process jumps directly from step 10 to step 19, and the boost pressure P _B is immediately compared to the first high load determination value P _BWOT1 without _changing to the second high load determination value P _BWOT1.
BWOT2 and does not determine the proceeds high load to a step 16 if the low pressure than P _BWOT2 comparison (F _WOT = 0), the determined (F _WOT = 1) fuel increase and jump high load in step 20 exceeds P _BWOT2 Run.

[0042] Thus intercooler temperature T _WIC is time considerably higher second high load determination the value P _BWOT2 in the criterion high load determination immediately able to set in the first high load determination value P _BWOT1 smaller value And then we are taking proper measures to prevent knocking.

When it is judged in Step 18 or Step 19 that the load is high, the processing proceeds to Step 20, and if K _TW2 and K _WOT are compared, if K _TW2 <K _WOT , the processing proceeds to Step 21 and the timer tmWOT is set. 0, the high load determination flag F
_It is determined that _WOT is "1" and the load is high (step 22), the high load increase coefficient K _WOT is 1.0, and the fuel is not increased depending on K _WOT (step 17), but the low water temperature increase coefficient K _TW2 is used.

When K _{TW2 ≤K WOT in} step 20, the _routine proceeds to step 25, where the correction coefficient X _WOT according to the engine water temperature T _W is retrieved from the table, and in the next step 26, the high load increase coefficient K
_WOT is multiplied by this correction coefficient X _WOT to obtain a new high load increase coefficient K _WOT .

Then, it is determined in the next step 27 whether or not the new high load increasing coefficient K _WOT exceeds the limit value K _WOTX.
If it is _exceeded , the limit value K _WOTX is _set as the high load increase coefficient K _WOT (step 28). If it is not _exceeded , the step 28 is skipped and the high load increase coefficient K _WOT obtained in step 26 is used as it is. Continue to 29.

In step 29, the timer time tmWOT is set to 0, then the high load determination flag F _{WOT is set} to "1" to determine a high load (step 30), and the low water temperature increasing coefficient K _{TW2 is set} to 1.
The fuel quantity is not increased by the low water temperature increase coefficient K _TW2 (step 31) but is increased by the high load increase coefficient K _WOT .

On the other hand, when the routine proceeds to step 23 from any one of steps 7, 8 and 9, the boost pressure P _{B is set} to the first value.
If the boost pressure P _B is low compared to the high load determination value P _BWOT1 , the process proceeds to step 32, the timer tmWOT is set to 0, and the high load determination flag F _{WOT is set} to “0” in the next step 33 to reduce the low load. Then, K _{WOT is set} to 1.0 (step 17).

If the boost pressure P _B exceeds the first high load determination value P _BWOT1 in step 23, the steps from step 23 to step
The _routine proceeds to 24, where it is judged whether the engine water temperature T _W is a high water temperature higher than the predetermined value T _{WWOTO. If} it is a high water temperature, the process jumps to step 25, and in the subsequent step 30, it is judged to be a high load (F _WOT =
1) The high load increase coefficient K _WOT is used as the fuel increase coefficient.

When T _{W ≤T WWOTO} and the water temperature is not high, the _routine jumps from step 24 to step 20 to increase the low water temperature increase coefficient K _TW2
And the high load increase coefficient K _WOT are compared to determine which increase coefficient is to be used. In any case, the high load is determined (step 22 or step 30).

In step 6, the throttle opening θ _TH
However, when it is determined that the engine is fully opened, the routine jumps to step 20, and thereafter, the high load determination and the increase of the fuel are immediately made without a delay.

As described above, when the throttle opening θ _TH is not fully opened, the sensor is normal, the engine speed N _E is not low, and the engine water temperature T _W is not high, P _BWOT1 ≤
At P _BWOT2 , _{even if} the boost pressure P _B rises and exceeds the first high load judgment value P _BWOT1 , it is not judged as a high load until the timer time tmWOT times up, and the effect of temporary overshoot is avoided. If the boost pressure P _B may exceed the second high load judgment value P _BWOT2 even before the timer time tmWOT _expires , it is immediately judged to be high load (F _WOT = 1), The amount is increased to change the air / fuel ratio to prevent knocking.

When P _BWOT1 > P _BWOT2 , the intercooler water temperature T _WIC is high, and knocking is _{likely to occur. Therefore} , the second high load judgment value P _BWOT1 is set lower than the second value. The high load determination value P _BWOT2 is used as a determination reference so that the high load determination can be performed immediately so as to properly prevent knocking.

In the above embodiment, the first high load determination value P _BWOT1 and the second high load determination value P _{BWOT2 are} determined by the intercooler water temperature T _WIC in steps 2 and 3 of the high load determination processing routine as shown in FIG. Has been decided,
The first high load judgment value P _BWOT1 is substantially constant, and the second high load judgment value P _BWOT2 is changed to change the first high load judgment value P _BWOT2 to high water temperature.
_{Although the} value smaller than _BWOT1 is adopted, the high load determination value may be determined as shown in FIG.

That is, in FIG. 6, the second high load judgment value P _BWOT2 is always the first with _respect to the intercooler water temperature T _WIC .
It is larger than the high load judgment value P _BWOT1 and also maintains a substantially constant difference.

When the intercooler water temperature T _WIC is in the normal temperature state, both the first high load judgment value P _BWOT1 and the second high load judgment value P _BWOT2 are set to a certain constant value, but a certain temperature A ₂ (for example, 60 2) high load judgment value P
_BWOT2 by gradually decreasing the value as a high load determination is carried out promptly, also somewhat higher temperatures C than the temperature A _2
When it becomes ₂ or more, the first high load judgment value P _BWOT1 is gradually decreased to set the supercharging pressure for operating the timer to a smaller value, and the first high load judgment value P _BWOT1 and the second high load judgment value P _{BWOT2 are set.} Any of the determination values is made small so that the high load determination can be easily performed. It is to be noted that if the temperature is set to the temperature B ₂ (for example, 90 ° C.) and the temperature is exceeded, the temperature becomes abnormally high.

In the above embodiment, the first high load judgment value P _BWOT1 and the second high load judgment value P _BWOT2 are determined based on the intercooler water temperature T _WIC . However, as shown in FIG. The first high load determination value P _BWOT1 and the second high load determination value P _BWOT2 may be determined based on the supply pressure change rate ΔP _B.

The first high load judgment value P _BWOT1 always maintains a constant value, but the second high load judgment value P _BWOT2 is larger than the first high load judgment value P _BWOT1 while the supercharging pressure change rate ΔP _B is small. When the rate of change X is set to a certain value and exceeds a certain rate of change X, the value is gradually reduced so that high load determination can be performed quickly.

That is, when the rate of change in supercharging pressure ΔP _B is large, it is a transitional time, and it is possible to prevent the occurrence of knocking by speeding up the high load determination.

[0059]

According to the first aspect of the present invention, when the first high load determining means determines that the supercharging pressure is higher than the first predetermined value and continues for a predetermined time, the high load state is detected. Exceeds a second predetermined value which is usually higher than the first predetermined value, the second high load determination means can immediately make a high load determination regardless of the predetermined time, and the responsiveness at the time of supercharging can be improved. It is possible to improve the knocking prevention measures promptly, and change the second predetermined value to an appropriate value according to the intercooler water temperature by the changing means to speed up the high load operation state where knocking easily occurs. Judgment can be taken more appropriately and knocking prevention measures can be taken.

According to the second aspect of the present invention, the second predetermined value is changed to an appropriate value in accordance with the change rate of the supercharging pressure, so that the high load operating state where knocking is likely to occur at the time of supercharging or the like can be speeded up. Judgment can be taken more appropriately and knocking prevention measures can be taken.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an intake control system of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a control procedure of this embodiment.

FIG. 3 is a diagram showing a high load determination value for an intercooler water temperature.

FIG. 4 is a diagram showing a first predetermined time with respect to a supercharging pressure change rate.

FIG. 5 is a diagram showing a second predetermined time with respect to the intercooler water temperature.

FIG. 6 is a diagram showing a high load determination value with respect to the intercooler water temperature of another embodiment.

FIG. 7 is a diagram showing a high load determination value with respect to a supercharging pressure change rate of another embodiment.

[Explanation of symbols]

E ... Engine body, A ... Air cleaner, SC ... Mechanical turbocharger,
IC ... Ink cooler, C ... Control means, 1 ... Intake passage, 2
... Exhaust passage, 3 ... Bypass passage, 4 ... Throttle valve, 5
... by-pass valve, 6 ... control chamber, 7 ... conduit, 8 ... electromagnetic switching valve, 9 ... conduit, 10 ... air cleaner, 11 ... passage, 12 ... bypass valve drive means, 13 ... crank shaft, 19 ... supercharging pressure sensor, 20 ... Engine speed sensor, 21 ... Throttle opening sensor, 22 ... Bypass opening sensor, 23 ... Engine water temperature sensor, 25 ... Intercooler water temperature sensor, 26 ... Cooling water channel,
27 ... Water pump, 28 ... Radiator.

Claims (2)

[Claims] 1. An internal combustion engine having a supercharger and an intercooler, a supercharging pressure detecting means for detecting a supercharging pressure, an intercooler water temperature detecting means for detecting a water temperature of a cooling water circuit for an intercooler, A first high load determining means for determining a high load state when the supercharging pressure detected by the supercharging pressure detecting means exceeds a first predetermined value for a predetermined time, and the supercharging pressure detecting means. When the supercharging pressure detected by exceeds a second predetermined value which is higher than the first predetermined value when the water temperature of the intercooler cooling water circuit is a normal temperature, it is determined to be a high load state regardless of the predetermined time. High load determining means for changing the second predetermined value according to the intercooler water temperature detected by the intercooler water temperature detecting means. Judgment device. 2. In an internal combustion engine equipped with a supercharger, a supercharging pressure detecting means for detecting supercharging pressure, and a change rate calculating means for calculating a change rate of the supercharging pressure detected by the supercharging pressure detecting means. A first high load determining means for determining a high load state when a state in which the supercharging pressure detected by the supercharging pressure detecting means exceeds a first predetermined value continues for a predetermined time; A second high load determining means for determining a high load state regardless of the predetermined time when the supercharging pressure detected by the pressure detecting means exceeds a second predetermined value higher than the first predetermined value; A high load determination device for an internal combustion engine, comprising: a changing unit that changes the second predetermined value according to the change rate of the supercharging pressure calculated by the change rate calculating unit.