JP3116789B2 - Intake control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake control system for an internal combustion engine, and more particularly to an intake control system for an internal combustion engine suitable for controlling a vehicle-mounted internal combustion engine having a function of varying an intake pipe length.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Application Laid-Open No. HEI 4-13642.
As disclosed in No. 1, there is known an apparatus for varying the length of an intake pipe of a vehicle-mounted internal combustion engine. The conventional device includes an intake branch pipe communicating with each of a plurality of cylinders included in the internal combustion engine, and a surge tank communicating with the other end of the intake branch pipe. Two spaces are formed inside the surge tank to be in a communicating state or a separated state according to the state of the control valve.

[0003] A plurality of cylinders provided in an internal combustion engine are grouped by cylinders that do not cause intake interference with each other.
It can be divided into a first group and a second group. In the above-described conventional apparatus, the two branches formed in the surge tank communicate with the intake branch pipes communicating with the first group and the intake branch pipes communicating with the second group, respectively. Further, the two spaces in the surge tank both communicate with an intake pipe provided on the upstream side of the surge tank.

According to the above configuration, when the control valve provided in the surge tank keeps the two spaces shut off, no intake interference occurs inside the surge tank. In this case, the distance from the intake port of the internal combustion engine to the position where the intake interference occurs (hereinafter, this distance is referred to as the intake pipe length) is relatively long. On the other hand, when the control valve in the surge tank communicates the two spaces, intake interference occurs in the surge tank. In this case, the length of the exhaust pipe is relatively short.

[0005] The output characteristics of an internal combustion engine are affected by its intake characteristics. In general, in order to obtain excellent output characteristics in an internal combustion engine, it is known that a longer intake pipe length is advantageous in a low rotation range, while a shorter intake pipe length is advantageous in a high rotation range. . In the above-described conventional apparatus, the control valve is closed when the engine speed is lower than a predetermined threshold value. When the engine speed is higher than a predetermined threshold value, the control valve is opened. Therefore, according to the above-described conventional apparatus, excellent output characteristics can be obtained in a wide range from a low rotation range to a high rotation range.

The above-described conventional apparatus includes a negative pressure tank for storing a negative pressure of intake air, and a negative pressure actuator for driving a control valve using the negative pressure stored in the negative pressure tank as a power source.
The intake negative pressure is introduced into the negative pressure tank when the intake negative pressure is lower than a predetermined pressure. When a negative pressure sufficient to drive the negative pressure actuator is stored in the negative pressure tank, the length of the intake pipe can be changed by supplying the negative pressure to the negative pressure actuator. Therefore, according to the above-described conventional apparatus, it is possible to appropriately drive the control valve without using any special power source.

[0007]

In an internal combustion engine, a reference intake air amount or a reference intake pressure is calculated based on the engine speed NE and the throttle opening TA, and the calculated value is controlled as a control parameter. May be executed. The reference intake air amount and the reference intake pressure are the intake air amount and the intake pressure that are assumed to be realized in the reference environment when the internal combustion engine exhibits the intake characteristics originally planned.

Accordingly, when the internal combustion engine exhibits the originally planned intake characteristics, the reference intake air amount and the reference intake pressure are
The difference between the actual intake air amount and the actual intake pressure can be considered to be caused by the difference between the reference environment assumed in advance and the actual environment where the internal combustion engine is placed. The control using the reference intake air amount and the reference intake pressure is performed for the purpose of correcting the influence caused by the difference between the reference environment and the real environment, assuming that the above assumption is satisfied.

In the above-described conventional apparatus, when a negative pressure is sufficiently stored in a negative pressure tank, a long intake pipe length is used in a low engine speed region, and a short intake pipe length is used in a high engine speed region. Realized respectively. When the device related to the internal combustion engine is mounted, the reference intake air amount and the reference air pressure are set on the premise that the intake characteristics of the internal combustion engine change as described above according to the engine speed. Therefore, under the situation where the negative pressure actuator functions normally, by executing the control using the reference intake air amount or the reference intake pressure,
Excellent drivability can be realized.

However, in the above conventional apparatus, when the engine speed is repeatedly increased or decreased, the negative pressure actuator is repeatedly driven, and a negative pressure sufficient to drive the negative pressure actuator remains in the negative pressure tank. May not happen. When the negative pressure in the negative pressure tank is consumed in this manner, the intake pipe length does not change even if the engine speed is increased or decreased, so that the initially expected intake characteristics cannot be obtained in the internal combustion engine.

When the intake characteristics of the internal combustion engine deviate from the characteristics originally expected, the difference between the reference intake air amount and the reference intake pressure and the actual intake air amount and the actual intake pressure is calculated based on a reference environment assumed in advance, In addition to the difference from the actual environment in which the internal combustion engine is placed, a change in the intake characteristic of the internal combustion engine is superimposed.
Therefore, in such a situation, if control using the reference intake air amount or the reference intake pressure is executed, the drivability of the internal combustion engine may be rather deteriorated.

The above-mentioned conventional apparatus does not have a function of detecting a state in which the negative pressure actuator falls into an inoperable state. For this reason, in the internal combustion engine equipped with the above-described conventional device, control using the reference intake air amount or the reference intake pressure cannot be stopped after the negative pressure actuator has become inoperable. In this regard, the above-described conventional apparatus still leaves room for improvement in always maintaining good drivability of the internal combustion engine.

The present invention has been made in view of the above points, and has a function of changing the length of an intake pipe, and distinguishes between a situation in which the intake pipe length changes and a situation in which the intake pipe length does not change. It is an object of the present invention to provide an intake control device for an internal combustion engine which can be provided.

[0014]

The above object is achieved by the present invention.
And a negative pressure tank that stores the negative pressure of the intake air of the internal combustion engine, and a negative pressure actuator that operates using the negative pressure stored in the negative pressure tank as a power source to change the length of the intake pipe of the internal combustion engine. In an intake control device for an internal combustion engine,
Negative pressure introduction state detection means for detecting a predetermined operation state in which a predetermined negative pressure is guided to the negative pressure tank; and the negative pressure actuator after the predetermined operation state is detected by the negative pressure introduction state detection means An internal combustion engine comprising: an operation frequency counting unit that counts the number of times of operation; and an operation availability determination unit that determines that the negative pressure actuator is in an inoperable state when the count value of the operation frequency counting unit exceeds a predetermined number. This is achieved by the intake control device of the engine.

In the present invention, when the internal combustion engine is in a predetermined operating state, a predetermined negative pressure is introduced to the negative pressure tank. The negative pressure tank stores the negative pressure thus guided. The negative pressure actuator operates using a negative pressure stored in a negative pressure tank as a power source. The negative pressure in the negative pressure tank is consumed by a predetermined amount each time the negative pressure actuator operates.
After the predetermined negative pressure is introduced into the negative pressure tank, when the negative pressure actuator is operated a predetermined number of times, the negative pressure required to operate the negative pressure actuator does not remain in the negative pressure tank. When such a state is formed, thereafter, the negative pressure actuator becomes inoperable until a negative pressure is again introduced into the negative pressure tank. The operation number counting means, after the negative pressure introduction state detection means has detected a predetermined operation state, that is,
After a state where a predetermined negative pressure is introduced into the negative pressure tank is formed, the number of times the negative pressure actuator is operated is counted. When the number of times of operation of the negative pressure actuator reaches a predetermined number, the negative pressure required for the operation of the negative pressure actuator does not remain in the negative pressure tank, that is, the negative pressure actuator operates. Judge that it is impossible.

[0016] The above object is as described in claim 2.
In an intake control apparatus for an internal combustion engine having a control valve for changing an intake pipe length of the internal combustion engine, before and after a command for requesting the control valve to change a state is issued, a change amount occurring in an intake air amount and a change amount occurring in an intake pressure Change amount detection means for detecting at least one of the following, and when the detection value of the change amount detection means is smaller than a predetermined value, an operation state determination means for determining that the control valve has malfunctioned, This is also achieved by an intake control device for an internal combustion engine having the following.

In the present invention, when the state of the control valve changes, the intake pipe length changes before and after the change. When the intake pipe length changes, the intake characteristics of the internal combustion engine change. Further, when the intake characteristics of the internal combustion engine change, a large change occurs in the intake air amount and the intake pressure. Therefore, when the control valve is operating normally, the change amount detecting means detects a relatively large change amount. The operating state determining means determines that the control valve is not operating normally when the change amount is smaller than a predetermined value.

According to a third aspect of the present invention, a negative pressure tank for storing an intake negative pressure of an internal combustion engine and a negative pressure stored in the negative pressure tank operate as a power source. A negative pressure actuator that changes the intake pipe length of the
A negative pressure estimating means for estimating a negative pressure stored in the negative pressure tank based on a load of the internal combustion engine, and the negative pressure estimating means according to an estimated value of the negative pressure estimating means. Operable number setting means for setting the operable number of pressure actuators; actuation number counting means for counting the number of actuations of the negative pressure actuator after the operable number is set by the operable number setting means; When the count value of the number-of-times counting means exceeds the operable number of times, the operation is also achieved by an intake control device for an internal combustion engine including: an operability determining means for determining that the negative pressure actuator is in an inoperable state.

In the present invention, the intake negative pressure of the internal combustion engine is:
The lighter the load on the internal combustion engine, the lower the pressure. Therefore, the negative pressure of the internal combustion engine is stored in the negative pressure tank as the load becomes lighter. The negative pressure estimating means estimates that the lighter the load of the internal combustion engine, the lower the negative pressure in the negative pressure tank. The negative pressure actuator can operate more as the negative pressure stored in the negative pressure tank is lower. The operable number setting means sets a greater number of operable times as the estimated value of the negative pressure estimating means is lower, that is, as the negative pressure in the negative pressure tank is estimated to be lower. After the number of operable times is set by the operable number setting means, when the negative pressure actuator is operated by the operable number of times, the negative pressure in the negative pressure tank is consumed, and the negative pressure actuator becomes inoperable. . In such a case, the operation availability determination means determines that the negative pressure actuator is in an inoperable state.

Further, an object of the present invention is to provide an intake control system for an internal combustion engine having a control valve for changing an intake pipe length of the internal combustion engine, the reference intake air amount corresponding to the operating state of the internal combustion engine. And a real intake air amount, and at least one of a relation between a reference intake pressure and an actual intake pressure corresponding to an operation state of the internal combustion engine. This is also achieved by an intake control device for an internal combustion engine, comprising: an operating state determining means for determining that the control valve has malfunctioned when the relationship changes beyond a predetermined level.

In the present invention, the reference intake air amount and the reference intake pressure corresponding to the operating state of the internal combustion engine are determined on the assumption that the control valve operates properly, that is, the intake pipe length changes appropriately. On the other hand, the actual intake air amount and the actual intake pressure have different values depending on whether the control valve operates properly or not. Therefore, the detection result of the reference actual relation detecting means is substantially constant when the control valve operates normally, and largely fluctuates when the control valve does not operate normally. The operation state operation state determination means,
When a change that does not occur when the control valve is operating normally is detected by the reference actual relation detection stage, it is determined that the control valve has malfunctioned.

[0022]

FIG. 1 shows a system configuration diagram of an embodiment of the present invention. The system according to the present embodiment includes an electronic control unit (hereinafter, referred to as an ECU) 10 and an internal combustion engine 1.
2 is provided. The system of the present embodiment, as described below,
It is controlled by the ECU 10.

The internal combustion engine 12 is a V-type six-cylinder internal combustion engine, and has six cylinders # 1 to # 6 from a first cylinder to a sixth cylinder.
It has. Each cylinder has a built-in piston 14. The piston 14 is connected to a crankshaft 18 via a connecting rod 16. Crankshaft 18
, A rotating body 20a is fixed. In the vicinity of the rotator 20a, a sensor unit 20b that generates a pulse signal at a cycle corresponding to the rotation speed of the rotator 20a is provided. The sensor unit 20b is connected to the ECU 10. The rotating body 20a and the sensor unit 20b constitute a crank angle sensor 20. The crank angle sensor 20 transmits a pulse signal to the ECU 10 every time the crankshaft 18 rotates a predetermined angle. The ECU 10 detects the rotation angle and the rotation speed of the crankshaft 18 based on the pulse signal.

Each cylinder # 1 to # 6 of the internal combustion engine 12 is provided with an intake port 22 and an exhaust port 24, respectively. Each intake port 22 has an intake valve 2
6, and the intake branch pipe 28 is communicated. In addition, an exhaust valve 30 is disposed at each exhaust port 24, and an exhaust branch pipe 32 is connected to the exhaust port 30.

Intake branch pipe 28 communicating with each of cylinders # 1 to # 6
Communicates with the surge tank 34 at the other end. An intake pipe 36 communicates with the surge tank 34. A throttle valve 38 that operates in conjunction with an accelerator pedal (not shown) is provided inside the intake pipe 36. In the vicinity of the throttle valve 38, a throttle sensor 40 for detecting the opening of the throttle valve 38 is provided. The output signal of the throttle sensor 40 is EC
It is supplied to U10.

The intake pipe 36 communicates with an air filter 42 at its end. Further, an intake air temperature sensor 44 is disposed downstream of the air filter 42 in the intake pipe 36. The intake air temperature sensor 44 outputs a signal corresponding to the temperature of the air that has passed through the air filter 42 and is drawn into the intake pipe 36, that is, the air drawn into the internal combustion engine 12.
The output signal of the intake air temperature sensor 44 is supplied to the ECU 10.

The intake pipe 36 also has an exhaust gas recirculation passage 46.
Has one end in communication. The exhaust gas recirculation passage 46 is a passage that connects an exhaust pipe (not shown) communicating with the downstream side of the exhaust branch pipe 32 and the intake pipe 36, and includes an exhaust gas recirculation control valve 48 in the middle thereof. Exhaust gas recirculation control valve 48
Is connected to the ECU 10 and realizes an opening degree according to a drive signal supplied from the ECU 10.

The pressure of the exhaust gas discharged from the internal combustion engine 12 is higher than the pressure in the intake pipe 36. Therefore, when the exhaust gas recirculation control valve 48 is opened, the exhaust gas corresponding to the opening amount is recirculated from the exhaust pipe toward the intake pipe 36. When the exhaust gas is recirculated into the intake pipe 36, the combustion temperature in each of the cylinders # 1 to # 6 can be reduced by the heat capacity of the exhaust gas. NO _X contained in the exhaust gas is unlikely to occur that the lower the combustion temperature. On the other hand, when the combustion temperature is excessively lowered, the output characteristics of the internal combustion engine 12 are deteriorated, and a large amount of unburned components such as HC are generated in the exhaust gas. In the internal combustion engine 12, the ECU 10 appropriately controls the opening degree of the exhaust gas recirculation control valve 48 according to the operating state of the internal combustion engine 12, so that excellent exhaust emissions can be obtained.

The surge tank 34 is provided with an intake pressure sensor 49 for detecting the internal pressure of the surge tank 34. The intake pressure sensor 49 generates an electric signal corresponding to the internal pressure of the surge tank 34 and supplies the signal to the ECU 10. A control valve 50 is provided inside the surge tank 34. A negative pressure actuator 52 is connected to the control valve 50 as a drive mechanism. The negative pressure actuator 52 includes a vacuum switching valve (hereinafter, referred to as a vacuum switching valve).
A negative pressure tank 56 is communicated via a VSV (referred to as VSV) 54. The VSV 54 is an electromagnetic valve that operates in response to a drive signal supplied from the ECU 10. When the ON signal is supplied from the ECU 10, the VSV 54 brings the negative pressure actuator 52 and the negative pressure tank 56 into a conductive state. When the ON signal is not supplied, the negative pressure actuator 52 is opened to the atmosphere while the negative pressure actuator 52 and the negative pressure tank 56 are shut off.

The negative pressure tank 56 has a tank portion 56a and a check valve 56b. The tank portion 56a communicates with the VSV 54 as described above, and the surge tank 34
Is in communication with The check valve 56b is a one-way valve that allows only the flow of the fluid from the negative pressure tank 56 to the surge tank 34. Therefore, when the internal pressure of the negative pressure tank 56 is lower than the internal pressure of the surge tank 34, that is, the intake pressure PM of the internal combustion engine 12, the check valve 56b is kept closed. In this case, the negative pressure in the negative pressure tank 56 is maintained without being consumed. On the other hand, when the intake pressure PM of the internal combustion engine 12 becomes lower than the internal pressure of the negative pressure tank 56, the check valve 56b opens and the intake negative pressure PM is introduced into the negative pressure tank 56.

FIGS. 2 and 3 are conceptual diagrams showing the internal structure of the surge tank 34 and the connection between the intake branch pipe 28 and each of the cylinders # 1 to # 6 of the internal combustion engine 12. FIG. FIG.
Is formed when a predetermined operating negative pressure is supplied to the negative pressure actuator 52, that is, when an ON signal is supplied to the VSV 54 while an appropriate negative pressure is stored in the negative pressure tank 56. Is done. The state shown in FIG.
When a predetermined operating negative pressure is not supplied to the negative pressure actuator 52, that is, when the ON signal is not supplied to the VSV 54, or in the negative pressure tank 56, the operation pressure is lower than the operating negative pressure of the negative pressure actuator 52. This is formed when an ON signal is supplied to the VSV 54 in a situation where a low negative pressure is not stored. Hereinafter, for convenience of explanation, the state illustrated in FIG. 2 is referred to as an on state, and the state illustrated in FIG. 3 is referred to as an off state.

As shown in FIGS. 2 and 3, a partition 34a is provided inside the surge tank 34. The control valve 50 closes the space between the inner wall of the surge tank 34 and the partition wall 34a when turned on as shown in FIG.
Further, it is provided so as to open the space between the inner wall of the surge tank 34 and the partition wall 34a when turned off as shown in FIG. Therefore, the internal space of the surge tank 34 is
In the ON state, the first space 34b and the second space 34c are separated. In addition, the first space 34b and the second space 34c are in a state of communicating with each other in the off state.

In each of the cylinders # 1 to # 6 of the internal combustion engine 12, the intake, compression, explosion, and exhaust strokes are sequentially performed. In the internal combustion engine 12, the cylinders # 1, # 3, and # 5 advance the above-described strokes with a phase shift of 4π / 3 [rad]. Similarly, the cylinders # 2, # 4, and # 6 also advance the above-described process by shifting the phase by 4π / 3 [rad]. The intake stroke of each cylinder is completed while the crankshaft 18 rotates through a smaller rotation angle than 4π / 3 [rad]. Thus, between # 1, # 3 and # 5 cylinders of the internal combustion engine 12,
No intake interference occurs between the # 2, # 4, and # 6 cylinders. Hereinafter, cylinders # 1, # 3, and # 5 are referred to as a first group, and cylinders # 2, # 4, and # 6 are referred to as a second group.

As shown in FIGS. 2 and 3, the first branch 34b of the surge tank 34 communicates with the first group of cylinders which do not cause intake interference with each other. The second space 3 of the surge tank 34
An intake branch pipe 28 communicating with the second group of cylinders that does not cause intake interference with each other is connected to 4c.
Therefore, when the control valve 50 is in the ON state, no intake interference occurs in the surge tank 34. in this case,
The intake pulsation corresponding to the engine speed NE is determined for each cylinder # 1 to # 6.
Occurs in the path from the intake port 22 to the connection between the surge tank 34 and the intake pipe 36. On the other hand, when the control valve 50 is off, intake interference occurs in the surge tank 34. In this case, the intake pulsation corresponding to the engine speed NE is generated in the intake branch pipe 28 communicating with the intake port 22 of each of the cylinders # 1 to # 6.

The output characteristics of the internal combustion engine 12 are affected by the length of the path in which intake pulsation occurs, that is, the intake pipe length. That is, in order to obtain excellent output characteristics in the internal combustion engine 12, it is advantageous to positively use the inertia effect of the intake air. For this purpose, when the intake stroke is performed in each of the cylinders # 1 to # 6, It is effective to guide a high-pressure wave near the intake port 22. Such a condition is realized when the intake pipe length is relatively long in a low rotation area where the engine speed NE is low, and when the intake pipe length is relatively short in a high rotation area where the engine speed NE is high.

In this embodiment, as will be described later, when the engine speed NE is smaller than the predetermined value NE ₀ and a large output torque is required, the control valve 50 is turned on. When the engine speed NE is equal to or higher than the predetermined value NE ₀ , the control valve 50 is turned off to achieve both the intake characteristics required in the low rotation region and the intake characteristics required in the high rotation region. Is being planned.

FIG. 4 shows the relationship between the engine speed NE and the output torque obtained when the ECU 10 drives the VSV 54 to satisfy the above function under the condition that the throttle valve 38 is maintained in the fully opened state (hereinafter, referred to as the output torque). (Referred to as WOT characteristics)
, A curve representing a WOT characteristic obtained when the control valve 50 is maintained in a closed state, and a curve representing the control valve 5.
5 shows a curve representing WOT characteristics obtained when 0 is maintained in a valve open state. As shown in FIG. 4, the WOT characteristic when the control valve 50 is kept in a closed state, the WOT characteristic when the control valve 50 is maintained in the open state, the magnitude before and after the engine speed NE ₀ The relationship is reversed. Therefore, E
When the CU 10 drives the VSV 54 as described above, excellent output characteristics can be obtained over a wide range from the low rotation range to the high rotation range as shown by the curve.

FIG. 5 shows that the ECU 10 sends an ON signal to the VSV 54.
And the VSV5
4 where no ON signal is supplied (except for the matte area)
Region). As shown in FIG. 5, the ECU 10 includes an engine
The rotational speed NE is equal to the predetermined rotational speed NE ₀Smaller than and
The throttle opening TA is equal to the predetermined opening TA₀Over
ON signal is output to the VSV 54 only. VSV54 is E
If it operates normally according to the command of CU10,
When a high output torque is required in the
Is controlled to be in a closed state.
0 is controlled to the valve open state, and the WOT shown in FIG.
The characteristics are realized.

In the internal combustion engine 12, for example, when the engine speed NE is finely adjusted while a high output torque is required, TA> TA ₀ is satisfied, and the engine speed NE is NE _0. A situation occurs in which the number is increased or decreased across the line. If such a situation continues, the negative pressure in the negative pressure tank 56 is repeatedly consumed by the negative pressure actuator 52, and eventually the negative pressure sufficient to operate the negative pressure actuator 52 does not remain in the negative pressure tank 56. Reach. In this case, thereafter, the control valve 50 operates until the negative pressure is again introduced into the negative pressure tank 56.
The off state shown in FIG. 3, that is, the valve open state is maintained.

As described above, when the control valve 50 functions normally, the WOT characteristic shown in FIG. 4 is realized. Further, in a situation where the control valve 50 is always kept open, the WOT characteristic shown in FIG. 4 is realized. Therefore, the internal combustion engine 12 of the present embodiment includes a possibility that the WOT characteristic is different depending on whether the control valve 50 is in the movable state or not.

Incidentally, in the internal combustion engine 12, the high altitude learning value KPA for correcting the fluctuation of the atmospheric pressure is used for controlling the exhaust gas recirculation control valve 48. The amount of exhaust gas recirculated from the exhaust pipe to the intake pipe 36 through the exhaust recirculation valve 48 is determined by the differential pressure between the internal pressure of the exhaust pipe and the internal pressure of the intake pipe 36 and the opening of the exhaust recirculation control valve 48. Value. The change in the atmospheric pressure affects the pressure difference between the internal pressure of the exhaust pipe and the internal pressure of the intake pipe 36. Therefore, in order to accurately control the flow rate of the recirculated exhaust gas, it is necessary to control the exhaust gas recirculation control valve 48 in consideration of the influence of the atmospheric pressure. Highland learning value KPA mentioned above
Is a correction coefficient used to implement control satisfying such a request in the internal combustion engine 12.

FIG. 6 shows a flowchart of an example of a control routine executed by the ECU 10 to update the highland learning value KPA. The routine shown in FIG. 6 is a periodic interrupt routine that is started every predetermined time. When the routine shown in FIG. 6 is started, first, in step 100,
Various parameters required for updating the highland learning value KPA are read. Specifically, the crank angle sensor 20,
Based on output signals from the throttle sensor 40 and the intake pressure sensor 49, the engine speed NE and the throttle opening T
A and the intake pressure PM are read.

Next, at step 104, the reference intake pressure PMTA is calculated according to the following equation. PMTA = tPMTAB * KPA (1) tPMTAB shown in the above equation (1) is a value obtained by searching a PMTAB map stored in the ECU 10 with the throttle opening TA and the engine speed NE. is there. PMT
In the AB map, the intake pressure PM obtained when the atmospheric pressure is a reference value and the internal combustion engine 12 exhibits reference intake characteristics is set using the engine speed NE and the throttle opening TA as parameters. ing. Therefore, in the above equation (1), the intake pressure PM obtained when the internal combustion engine 12 is operated under the reference atmospheric pressure is substituted for tPMTAB.

TPMTAB substituted in the above equation (1)
Is always a constant value for the combination of NE and TA without being affected by the atmospheric pressure. On the other hand, the actual intake pressure PM is affected by the atmospheric pressure and becomes low when the atmospheric pressure is low, and becomes high when the atmospheric pressure is high. Therefore, tPMTAB shown in the above equation (1)
Is larger than the actual intake pressure PM when the atmospheric pressure is lower than the reference atmospheric pressure, and is higher when the atmospheric pressure is higher than the reference atmospheric pressure. This value is smaller than the pressure PM.

KPA is a reference intake pressure PMT as described later.
A is updated so that A approaches the actual intake pressure PM. That is, when tPMTAB is larger than PM, the value is smaller than the reference value 1.0, and tPMTAB is smaller than PM.
Is smaller than the reference value 1.0, the value is updated to a value larger than the reference value 1.0. Therefore, if the value of the highland learning value KPA is an appropriate value corresponding to the actual atmospheric pressure, the reference intake pressure PM
TA and the actual air pressure PM have the same value.

In step 106, the PMTA calculated in the previous processing and the PMTA calculated in the current processing are determined.
It is determined whether or not the absolute value | ΔPMTA | of the deviation ΔPMTA from this is equal to or smaller than a predetermined threshold α. | ΔPMT
The condition of A | ≦ α is satisfied in a situation in which the operating state of the internal combustion engine 12 is stable, whereas it is not satisfied in a situation in which the operating state of the internal combustion engine changes rapidly, such as during rapid acceleration or rapid deceleration. Becomes

In step 106, | ΔPMT
If it is determined that A | ≦ α is not established, since an error due to a time lag or the like is likely to be superimposed between the actual operating state of the internal combustion engine 12 and the PMTA calculated in step 104, It is determined that the highland learning value KPA should not be updated, and the current routine ends without any further processing. On the other hand, if it is determined in step 106 that | ΔPMTA | ≦ α is satisfied, step 1 is performed to proceed with the KPA update process.
08 is executed.

In step 108, the above-mentioned step 104
And the intake pressure sensor 49
It is determined whether or not the deviation PMTA-PM from the actual intake pressure PM obtained based on the output signal is equal to or larger than a predetermined value β (> 0). As described above, if the highland learning value KPA is an appropriate value according to the actual atmospheric pressure, PMTA and PM are equal. Therefore, in such a case, the condition of step 108 is not satisfied. On the other hand, the highland learning value KPA
Is larger than an appropriate value corresponding to the actual atmospheric pressure, PMTA becomes larger than PM. Such a situation occurs, for example, when the vehicle goes uphill from a lowland to a highland and the atmospheric pressure decreases, and the actual intake pressure PM
Occurs when the temperature decreases. If it is determined that the condition of step 108 is satisfied as the actual intake pressure PM decreases, the process of step 110 is executed.

In step 110, it is determined whether or not the value obtained by subtracting the predetermined value γ from the highland learning value KPA is equal to or higher than MIN which is set in advance as the lower limit value of KPA.
If it is determined that KPA-γ ≧ MIN holds, in step 112, KPA-γ is set to the new highland learning value KPA, and then the current routine is terminated. On the other hand, if it is determined that KPA−γ ≧ MIN is not established, the lower limit value MIN is set to the new highland learning value KPA in step 114, and then the current routine is terminated.

As described above, when PMTA-PM ≧ β is satisfied, the highland learning value KPA is reduced with MIN as the lower limit every time this routine is executed. Highland learning value K
When PA is decreased, the value of the reference intake pressure PMTA decreases, and PMTA-PM approaches “0”. Therefore, the condition of step 108 is not satisfied, and the process of decreasing the highland learning value KPA is stopped.

In step 108, PMTA-
If it is determined that PM ≧ β is not satisfied, it is determined in step 116 whether PMTA−PM ≦ −β (<0) is satisfied. Such a condition occurs, for example, when the vehicle descends from a high altitude to a low altitude and the atmospheric pressure rises, and the actual intake pressure PM rises with the change. If it is determined that the condition of step 116 is satisfied as the actual intake pressure PM increases, the process of step 118 is executed next.

At step 118, it is determined whether or not the value obtained by adding the predetermined value γ to the highland learning value KPA is equal to or greater than MAX which is set in advance as the upper limit value of KPA. K
If it is determined that PA + γ ≧ MAX holds, in step 112, KPA + γ is set to the new highland learning value K.
After PA, the current routine is terminated. on the other hand,
If it is determined that KPA + γ ≧ MAX is not established, the upper limit value MAX is set to the new highland learning value KPA in step 114, and then the current routine is terminated.

As described above, when PMTA-PM ≦ -β is satisfied, the highland learning value KPA is increased with MAX as the upper limit every time this routine is executed. When the highland learning value KPA increases, the value of the reference intake pressure PMTA increases, and PMTA-PM approaches "0". Therefore, the condition of step 116 is not satisfied, and the process of increasing the highland learning value KPA is stopped.

When the deviation between the reference intake pressure PMTA and the actual intake pressure PM is small and -β <PMTA-PM <β is satisfied, the conditions in steps 108 and 116 are not satisfied. In this case, it can be determined that the highland learning value KPA is set to an appropriate value, that is, it is not necessary to update the KPA. Therefore, the above step 1
If it is determined in step 16 that the condition is not satisfied, the current routine is terminated without any further processing.

As described above, according to the control routine shown in FIG. 6, the high altitude learning value KPA can be increased or decreased in accordance with the actual atmospheric pressure based on the difference between the reference intake pressure PMTA and the actual intake pressure PM. it can. In this case, the highland learning value KPA
Can be grasped as a substitute characteristic value of the atmospheric pressure surrounding the vehicle. Therefore, by using such a KPA, the exhaust gas recirculation control valve 48 can be controlled with high accuracy.

By the way, in the routine shown in FIG.
In calculating the reference intake pressure PMTA, the engine speed N
Reference is made to a PMTAB map in which E and the throttle opening TA are set as parameters. As mentioned above, PM
The TAB map is a map showing the intake pressure PM obtained when the internal combustion engine 12 operates under the reference environment. The internal combustion engine 12 is, as described above, a WO shown by a curve in FIG.
Either the T characteristic or the WOT characteristic indicated by the curve is realized.

The change in the WOT characteristic occurs when the intake characteristic of the internal combustion engine 12 changes. Therefore, two types of WOT characteristics are realized in the internal combustion engine 12.
This means that two kinds of intake characteristics are realized in the internal combustion engine 12. The intake pressure PM obtained when the internal combustion engine 12 operates under the reference environment is affected by the intake characteristics of the internal combustion engine 12. Accordingly, the intake pressure has a different value between the case where the internal combustion engine 12 realizes the WOT characteristic indicated by the curve and the case where the internal combustion engine 12 realizes the WOT characteristic indicated by the curve.

In the present embodiment, the PMTAB map stored in the ECU 10 is set on the assumption that the internal combustion engine 12 realizes the WOT characteristic indicated by the above curve.
Therefore, when the control valve 50 operates properly according to the command of the ECU 10, the reference intake pressure PMTA and the actual intake pressure PM
The KPA can be set to an appropriate value by updating the KPA based on the deviation from. However, when the control valve 50 does not operate in response to a command from the ECU 10, the reference intake pressure PMTA itself may have a value that greatly deviates from the intake pressure PM realized for NE and TA. Therefore, under such circumstances, KP
If the update of A is continued, the KPA may be erroneously learned.

The system according to the present embodiment monitors whether the control valve 50 is in an operable state in order to avoid such inconvenience. If the control valve 50 is inoperable, the high altitude learning value KPA It is characterized in that the update of the file is stopped. Such a characteristic function is realized by the ECU 10 executing a control routine shown in FIG. 7 and FIG.

FIG. 7 shows the state of VS after the internal combustion engine 12 becomes idle and a sufficient negative pressure is stored in the negative pressure tank 56.
7 shows a flowchart of an example of a routine for counting the number of times that the V54 has been turned on. The routine shown in FIG. 7 is a periodic interruption routine that is started every predetermined time.

When the routine shown in FIG. 7 is started, first, in step 200, it is determined whether or not a flag (hereinafter referred to as an XACIS flag) for instructing the VSV 54 to supply an ON signal is turned on. Is determined.
As a result, if it is determined that the XACIS flag is not on, the current routine is terminated without any further processing.

On the other hand, in step 200, XA
If it is determined that the CIS flag is on, it is determined in step 202 whether the XACIS flag was on at the time of the previous processing. As a result, when it is determined that the XACIS flag is already in the ON state from the previous processing, it is determined that the ON signal has not been supplied to the VSV 54 from the previous processing to the current processing. This routine ends without any further processing.

In step 202, if it is determined that the XACIS flag was not turned on at the time of the previous processing, the VAC is changed from the time of the previous processing to the time of this processing.
It can be determined that the ON signal has been supplied to the SV 54. In this case, in step 204, the counter N _X
Is incremented, and the current routine ends. The counter N _X is a counter that is reset to “0” when the internal combustion engine 12 enters an idle state, as described later. Therefore, the value of the counter N _X is the coefficient by the routine shown in FIG. 7 represents the number of times VSV54 after the latest time when the internal combustion engine 12 becomes idle is actuated.

FIG. 8 shows a flowchart of an example of a control routine executed by the ECU 10 to determine whether or not high altitude learning is to be performed, using the value of the counter N _X described above. FIG.
Is a periodic interruption routine started every predetermined time. When the routine shown in FIG. 8 is started, first, in step 300, the throttle sensor 4
It is determined whether or not the idle contact 0 is turned on, that is, whether or not the internal combustion engine 12 is in an idle state. As a result, if it is determined that the idle contact is ON, the counter N _X is cleared in step 302, and then the current routine is terminated.

The lowest negative pressure is introduced into the negative pressure tank 56 when the internal combustion engine 12 is idle. The negative pressure introduced into the negative pressure tank 56 is the VSV 54
Is consumed by the negative pressure actuator 52 each time is operated. The control valve 50 can operate until the internal pressure of the negative pressure tank 56 becomes higher than the operating negative pressure of the negative pressure actuator 52. The number of times the control valve 50 can operate under the condition that the negative pressure is not resupplied after the internal combustion engine 12 is set to the idle state is determined by the capacity of the negative pressure tank 56, the consumption of the negative pressure actuator 52, and the like. . Assuming that the operable number is n, the control valve 50 controls the internal combustion engine 1
After 2 is in the idle state, it can reliably operate n times.

In the routine shown in FIG. 7, when it is determined in step 300 that the idle contact is not on, in step 304, the number of times the control valve 50 has been operated after the internal combustion engine 12 is in the idle state is counted. It is determined whether or not the value of the counter N _X exceeds the operable number n. As a result, when N _X > n is not satisfied, it can be determined that the control valve 50 is still in an operable state, that is, the internal combustion engine 12 exhibits the WOT characteristic shown in FIG. Therefore, when such a determination is made, in step 306, after the high altitude learning (the control shown in FIG. 6) is performed, the current routine is terminated.

On the other hand, in step 304, N _X
If it is determined that> n is satisfied, it can be determined that the control valve 50 has become inoperable, that is, the internal combustion engine 12 exhibits the WOT characteristic shown in FIG. Therefore, when such a determination is made, the current routine is terminated without executing the processing of step 306.

As described above, according to the system of the present embodiment, the update of the highland learning value KPA can be permitted only when the control valve 50 is in a state where it can be reliably operated according to the command of the ECU 10. . In other words, when there is a possibility that the control valve 50 does not operate, the update of the highland learning value KPA can be prohibited. For this reason, according to the system of the present embodiment, it is possible to prevent erroneous learning of the KPA caused by the control valve 50 not operating, and the internal combustion engine 12
Can always maintain good drivability.

FIG. 9 shows a second example of the operation region of the control valve 50 applicable to the system of the present embodiment.
In a system in which the KPA is updated regardless of whether the control valve 50 operates or not, it is necessary to suppress the frequency at which the control valve 50 becomes inoperable in order to reduce the frequency of erroneous learning of the KPA. To satisfy such conditions,
It is necessary to set a narrow area in which the XACIS flag is turned on, that is, to make a setting in which the XACIS flag is hardly turned on. In order to satisfy such a request, the ON area of the XACIS flag is set as shown in FIG.
Like the area, it is necessary to limit the area to a large TA.

On the other hand, as in this embodiment, the control valve 5
In a situation where the KPA is not erroneously learned even when 0 becomes inoperable, even if the XACIS flag is set to be easily turned on, no serious adverse effect occurs. Therefore, in the system of the present embodiment, (II) shown in FIG.
The area can also be set to the ON area of the XACIS flag. As described above, if the ON region of the control valve 15 can be set wide, it is possible to effectively use the intake inertia effect in a low rotation / light load region. In this regard, the system of the present embodiment also has an effect that the output characteristics of the internal combustion engine 12 can be improved in the low rotation speed region.

In the above embodiment, the ECU 10
Executes the processing of step 300, whereby the negative pressure introduction state detecting means of claim 1 executes the processing of steps 302 and 200 to 204 to count the number of times of operation according to claim 1. The means
By executing the processing of steps 304 and 306, the operation availability determination means according to claim 1 is realized.

FIG. 10 shows a system configuration diagram of a second embodiment of the present embodiment. In FIG. 10, the same components as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The system of the present embodiment is the first
Instead of the intake pressure sensor 49 provided in the system of the embodiment,
It is characterized in that an air flow meter 58 is provided.

The air flow meter 58 is a sensor that detects the mass flow rate G of the air flowing through the intake pipe 36 and supplies a signal corresponding to the detected value to the ECU 10. ECU10
Determines whether or not the highland learning value KPA can be updated according to the routines shown in FIGS. 7 and 8. If it is determined that the highland learning value KPA can be updated, the highland learning value KPA is determined based on a signal supplied from the air flow meter 58. Update the value KPA.

FIG. 11 shows a flowchart of an example of a control routine executed by the ECU 10 to update the high altitude learning value KPA based on the signal supplied from the air flow meter 58. The routine shown in FIG. 11 is a periodic interruption routine that is started every predetermined time. In FIG. 11, the same steps as those in the routine shown in FIG. 6 are denoted by the same reference numerals in parentheses, and description thereof is omitted.

When the routine shown in FIG. 10 is started, first, at step 400, various parameters required for updating the highland learning value KPA are read. Specifically, the crank angle sensor 20, the throttle sensor 40,
Based on the output signals of the intake air temperature sensor 44 and the air flow meter 58, the engine speed NE, the throttle opening TA,
The intake temperature THA and the mass flow rate G of the air flowing through the intake pipe 36 are read.

In step 402, based on the mass flow rate G and the engine speed NE, the intake air amount GN per one revolution of the engine
Is calculated. Next, at step 404, the reference intake air amount GNTA is calculated according to the following equation. In the following description, the amount of intake air means the mass flow rate of air.

GNTA = tGNTAB * FTHA * KPA (2) tGNTAB shown in the above equation (2) searches the GNTAB map stored in the ECU 10 with the throttle opening TA and the engine speed NE. It is the value obtained by GNT
In the AB map, the atmospheric pressure is a reference value, and the intake air temperature TH
The intake air amount GN obtained when A is the reference temperature and the internal combustion engine 12 exhibits the reference intake characteristics is set using the engine speed NE and the throttle opening TA as parameters. Therefore, in the above equation (2), the intake air amount GN obtained when the internal combustion engine 12 is operated at the reference atmospheric pressure and the reference intake air temperature is substituted for tGNTAB.

TGNTAB substituted in the above equation (2)
Is always a constant value for the combination of NE and TA without being affected by the atmospheric pressure and the intake air temperature THA. On the other hand, the actual intake air amount GN is affected by the atmospheric pressure and the intake air temperature THA, and is not always constant with respect to the combination of NE and TA. That is, the actual intake air amount G for the combination of NE and TA
N decreases as the atmospheric pressure decreases, and the intake air temperature TH
The higher the temperature of A, the smaller the amount. Therefore, tGNTAB shown in the above equation (2) is the actual intake when the atmospheric pressure is lower than the reference atmospheric pressure and when the intake air temperature THA is higher than the reference temperature. When the air pressure is larger than the air amount GN, and when the atmospheric pressure is higher than the reference atmospheric pressure, and when the intake air temperature THA is lower than the reference temperature, the actual intake air The value is smaller than the amount GN.

In the above equation (2), FTHA is an intake air temperature correction coefficient introduced for the purpose of correcting the above-mentioned influence of the intake air temperature. As the intake air temperature THA becomes higher than the reference temperature, it becomes higher. , To a value smaller than the reference value 1.0, and as the intake air temperature THA becomes lower than the reference temperature,
The value is updated to a value larger than the reference value 1.0. When the calculation of the above equation (2) is performed using the intake air temperature correction coefficient FTHA, the reference intake air amount GN in consideration of the actual intake air temperature THA is calculated.

When the reference intake air amount GNTA is larger than the actual intake air amount GN, the high altitude learning value KPA is smaller than the reference value 1.0.
Is smaller than GN, the value is updated to a value larger than the reference value 1.0. Therefore, if the value of the high altitude learning value KPA is an appropriate value corresponding to the actual atmospheric pressure, the reference intake air amount GNTA and the actual intake air amount GN are equal.

At step 406, the GNTA calculated in the previous processing and the GNTA calculated in the current processing are determined.
It is determined whether or not the absolute value | ΔGNTA | of deviation ΔGNTA | is smaller than or equal to a predetermined threshold value α. | ΔGNT
The condition of A | ≦ α is satisfied in a situation in which the operating state of the internal combustion engine 12 is stable, whereas it is not satisfied in a situation in which the operating state of the internal combustion engine changes rapidly, such as during rapid acceleration or rapid deceleration. Becomes

At step 406, | ΔGNT
If it is determined that A | ≦ α is not established, an error due to a time lag or the like is likely to be superimposed between the actual operating state of the internal combustion engine 12 and the GNTA calculated in step 404, and It is determined that the highland learning value KPA should not be updated, and the current routine ends without any further processing. On the other hand, when it is determined in step 406 that | ΔPMTA | ≦ α is satisfied, step 4 is performed in order to proceed with the KPA update process.
08 is executed.

In step 408, step 404 is performed.
And the actual intake air amount G obtained based on the output signal of the air flow meter 58.
It is determined whether the deviation GNTA-GN from N is equal to or greater than a predetermined value β (> 0). As described above, the highland learning value KP
If A is an appropriate value according to the actual atmospheric pressure, GNTA
And GN have the same value. Therefore, in such a case,
The condition of step 408 is not satisfied. On the other hand, when the value of the highland learning value KPA is larger than an appropriate value corresponding to the actual atmospheric pressure, GNTA is larger than GN. Such a situation occurs, for example, when the vehicle goes uphill from a low altitude to a high altitude and the atmospheric pressure decreases, and the actual intake air amount GN decreases with the change. If it is determined that the actual intake air amount GN decreases and the condition of step 408 is satisfied, the highland learning value KPA is updated in a decreasing direction by the processing of step 410 and thereafter.

In the above step 408, GNTA-
When it is determined that GN ≧ β is not satisfied, it is determined in step 416 whether GNTA−GN ≦ −β (<0) is satisfied. Such a condition occurs, for example, when the vehicle descends from a high altitude to a low altitude and the atmospheric pressure increases, and the actual intake air amount GN increases with the change. The actual intake air amount GN increases, and as a result, the above step 41
If it is determined that the condition 6 is satisfied, the highland learning value KPA is updated in the increasing direction by the processing after step 418.

If the difference between the reference intake air amount GNTA and the actual intake air amount GN is small and -β <GNTA-PM <β is satisfied, the conditions of steps 408 and 416 are not satisfied. In this case, it can be determined that the highland learning value KPA is set to an appropriate value, that is, it is not necessary to update the KPA. Therefore, if it is determined that the condition of step 416 is not satisfied, the current routine is terminated without any further processing.

As described above, according to the control routine shown in FIG. 11, the reference intake air amount GNTA and the actual intake air amount G
Based on the deviation from N, the highland learning value KPA can be increased or decreased according to the actual atmospheric pressure. Therefore, according to the system of the present embodiment, similarly to the system of the above-described first embodiment, the highland learning value KPA that can be grasped as the substitute characteristic value of the atmospheric pressure surrounding the vehicle can be obtained.

Further, as described above, the system according to the present embodiment operates only when it is determined that the high altitude learning value KPA can be updated by the routine shown in FIGS.
The control routine of FIG. 11 is executed. For this reason, according to the system of the present embodiment, erroneous learning of the KPA is prevented and the internal combustion engine 12
Can always maintain good drivability.

Next, a third embodiment of the present invention will be described. The intake control device for an internal combustion engine according to the present embodiment is realized by the ECU 10 executing the routine shown in FIG. 12 in the system configuration shown in FIG. FIG.
In the present embodiment, a flowchart of an example of a control routine executed by the ECU 10 to determine whether or not the highland learning value KPA can be updated is shown. The routine shown in FIG. 12 is a periodic interruption routine that is started every predetermined time.

When the routine shown in FIG. 12 is started, first, at step 500, it is determined whether or not the XACIS flag is off. When the XACIS flag is off, the control valve 50 is always in the open state regardless of whether or not a negative pressure is stored in the negative pressure tank 56. Accordingly, in such a situation, the highland learning value KPA is not erroneously learned even when the control valve 50 is inoperable. Therefore, if it is determined that the XACIS flag is off, in step 502, a flag indicating that KPA learning is permitted is set, and then the current routine is terminated.

In step 500, XACIS
If it is determined that the flag is not off, step 5
At 03, it is determined whether or not the XACIS flag has changed from off to on from the previous processing to the current processing. If it is determined that the XACIS flag has not changed from off to on, that is, if it is determined that the XACIS flag is continuously on, the current routine is terminated without any further processing. In this case, the determination as to whether or not to permit the KPA learning is held based on the previous determination.

If it is determined in step 503 that the XACIS flag has changed from off to on, then in step 504, the intake pressure PM at that time is reduced to PM.
Stored as ACIS. In the following step 506,
An ON signal is supplied to the VSV 54. Step 5
08, the intake pressure PM at that time and the above-described step 5
Difference ΔPM from PMACIS stored at 04 = PM−PM−PM
ACIS is calculated.

If the control valve 50 is in an operable state, V
At the same time that the ON signal is supplied to the SV 54, the control valve 50 should change from the open state to the closed state. Further, if the control valve 50 changes from the open state to the closed state, the intake characteristics of the internal combustion engine 12 change, and the pressure in the surge tank 34 should change greatly before and after the change. Accordingly, ΔPM calculated in step 508 is a relatively large value when the control valve 50 is operating normally.
When the control valve 50 does not operate normally, the value is relatively small.

When the processing in step 508 is completed,
After the VSV 54 is turned off in step 510,
In step 512, .DELTA.PM whether the predetermined threshold value .DELTA.PM ₀ or more is determined. As a result, ΔPM ≧ ΔP
When it is determined that M ₀ is not established, it can be determined that the control valve 50 is not operating normally. In this case, thereafter, in step 514, a flag indicating that KPA learning is prohibited is set, and then the current routine is terminated.

On the other hand, in step 512, ΔP
If it is determined that M ≧ ΔPM ₀ holds, the control valve 5
0 can be determined to be operating normally. In this case, the VSV 54 is turned on in step 516 and a flag indicating that KPA learning is permitted is set in step 518, and then the current routine is terminated.

As described above, in the routine shown in FIG. 12, it is determined whether or not the highland learning value KPA can be updated based on whether or not the control valve 50 is actually operating. Therefore, according to the system of the present embodiment, it is possible to clearly distinguish between the case where the control valve 50 is operable and the case where the control valve 50 is not operable. For this reason, according to the system of the present embodiment, it is possible to reliably prevent erroneous learning of the KPA due to a malfunction of the control valve 50, and to prevent the control valve 5 from malfunctioning.
The KPA can be updated whenever 0 is active.

By the way, in the above embodiment, before and after the ON signal is supplied to the control valve 50, that is, before and after a command to close the control valve 50 is issued, the surge valve 34 is generated in the surge tank 34. Although the operating state of the control valve 50 is determined based on the pressure fluctuation, the present invention is not limited to this. That is, the control valve 50 is controlled based on the pressure fluctuation before and after the command to open the control valve 50 is issued.
May be determined.

In the third embodiment described above, EC
U10 executes the processing of steps 503 to 508, and the change amount detecting means according to claim 2 executes the processing of steps 512 and 514, whereby the operation state determining means according to claim 2 executes the processing of steps 512 and 514. , Respectively.

Next, a fourth embodiment of the present invention will be described. The intake control device for an internal combustion engine of this embodiment is the same as that shown in FIG.
In the system configuration shown in FIG. 1, this is realized by the ECU 10 executing the routine shown in FIG. FIG.
In this embodiment, the ECU 10 determines that the high altitude learning value KPA
9 is a flowchart illustrating an example of a control routine that is executed to determine whether or not updating is possible. The routine shown in FIG. 13 is a periodic interrupt routine that is started every predetermined time. still,
In FIG. 13, the same steps as those in the routine shown in FIG. 12 are denoted by the same reference numerals in parentheses, and description thereof is omitted.

In the system according to the third embodiment described above, before and after the command for requesting the control valve 50 to change the state is issued, the detected value of the intake pressure sensor 49, that is, the intake pressure PM fluctuates beyond a predetermined value. Control valve 50 based on
Is operating. By the way, before and after the state of the control valve 50 changes, the intake air amount GN also changes, as does the intake pressure PM. The routine shown in FIG. 13 is a routine executed by the ECU 10 in the system shown in FIG. 10 to determine the operating state of the control valve 50 based on the amount of change in the intake air amount GN.

That is, in the routine shown in FIG. 13, when it is determined in step 603 that the XACIS flag has changed from off to on, step 604 is executed.
, The intake air amount GN at that time is GNACIS
Is stored as In step 608, the VSV
The intake air amount GN at the time when the ON signal is supplied to the
And the difference ΔGN = GN−GNACIS between the above and the GNACIS stored in step 604 is calculated. Then, in step 612, ΔGN is equal to a predetermined threshold value ΔGN
_When it is determined that the value is equal to or greater than ₀ , the learning of the KPA is permitted. On the other hand, when it is determined that ΔGN ≧ GN ₀ is not established, the learning of the KPA is prohibited.

As described above, according to the routine shown in FIG. 13, the control valve 5 is actually determined based on the change in the intake air amount GN.
It can be determined whether 0 is operating. Therefore, according to the system of the present embodiment, similarly to the system of the third embodiment, when the control valve 50 is operable,
The case where the control valve 50 is inoperable can be clearly distinguished.

In the above embodiment, the fluctuation of the intake air amount GN occurs before and after the ON signal is supplied to the control valve 50, that is, before and after the command to close the control valve 50 is issued. Although the operating state of the control valve 50 is determined based on the above, the present invention is not limited to this. That is, the operation state of the control valve 50 may be determined based on a change in the amount of intake air before and after the command to open the control valve 50 is issued.

In the fourth embodiment described above, the EC
U10 executes the processing of steps 603 to 608 shown in FIG. 13, and the change amount detecting means of claim 2 executes the processing of steps 612 and 614 to determine the operation state of claim 2. Means are each realized.

Next, a fifth embodiment of the present invention will be described. The intake control device for an internal combustion engine of the present embodiment can be realized by the system configuration shown in FIG. In the system shown in FIG. 1, a negative pressure is introduced into the negative pressure tank 56 when a negative pressure lower than the internal pressure of the negative pressure tank 56 is generated in the surge tank 34. Such conditions are not only when the internal combustion engine 12 is idle, but also when the internal combustion engine 1 is in an idle state.
2 also holds when the operation is performed in the light load region.

The system according to the first and second embodiments described above uses the control valve 5 after the internal combustion engine 12 enters the idle state.
It is determined whether or not the control valve 50 is in a movable state based on whether or not the number of times of operation of 0 has reached the predetermined number of times of operation n. Therefore, after the internal combustion engine 12 becomes idle, operation in the light load region and the control valve 50
When the operation in the low-rotation high-load region in which is turned on is repeated, the control valve is controlled despite the fact that a negative pressure capable of driving the negative pressure actuator 56 remains in the negative pressure tank 56. It may be determined that 50 is inoperable.
For this reason, in the systems of the first and second embodiments described above, a situation may occur in which the updating of the highland learning value KPA is prohibited when the control valve 50 is operable.

The system according to the present embodiment operates based on the change in the intake pressure PM and the operating state of the control valve 50.
By estimating the negative pressure stored in the negative pressure tank 56 during the operation in the light load region, and setting the number of times the control valve 50 can be operated according to the magnitude of the negative pressure, The feature is that the KPA can be updated in a wide area.

FIG. 14 shows an example of an ECU for realizing the above functions.
2 shows a flowchart of an example of a control routine executed by the control routine 10. The routine shown in FIG. 14 is a periodic interrupt routine that is started every predetermined time. When the routine shown in FIG. 14 is started, first, at step 700, the intake pressure P
M is read. Next, in step 702, the magnitude relationship between the stored value of this time the stored intake air pressure PM _i and the memory A are compared. As a result, when PM <A holds, in step 704, the intake pressure PM read at the time of the current process is stored in the memory A as a new stored value, and then the process of step 708 is executed. on the other hand,
If PM <A is not satisfied, the process of step 708 is performed without changing the stored value of the memory A. According to the above process, the memory A stores the intake pressure PM at the time when the pressure becomes the lowest in the past. As described below, the value of the memory A is substantially reset each time the control valve 50 operates. Therefore, the memory A stores the intake pressure PM at the time when the pressure becomes the lowest after the control valve 50 is operated.

The number of times the control valve 50 can be operated depends on the capacity of the negative pressure tank 56, the level of the negative pressure stored in the tank 56,
And it is determined by the negative pressure consumption of the negative pressure actuator 52. FIG. 15 is a characteristic diagram illustrating a relationship between the level of the negative pressure stored in the negative pressure tank 56 and the number of times the control valve 50 can operate. As shown in FIG. 15, in the system of the present embodiment, the control valve 50 controls the internal pressure PT of the negative pressure tank 56.
Once when B ₃ ≧ PT> B ₂ , B ₂ ≧ PT>
Twice if B ₁ is satisfied, 3 if B ₁ ≧ PT
Can be actuated twice.

The pressure PT in the negative pressure tank 56 rises due to the negative pressure consumed by the negative pressure actuator 52,
When the intake pressure PM becomes lower than PT, it decreases until it becomes equal to PM. Therefore, the pressure PT in the negative pressure tank 56 after the operation of the control valve 50 is
, Ie, the intake pressure PM stored in the memory A or lower. Therefore, in the system of this embodiment, at least once when B ₃ ≧ A> B ₂ is satisfied, and ₂ times when B ₂ ≧ A> B ₁ is satisfied.
If B ₁ ≧ A is satisfied more than three times, it can be determined that the control valve 50 can be reliably operated three times (upper limit of the number of times of operation).

In this routine, in step 708, it is determined whether or not the stored value of the memory A satisfies B ₃ ≧ A. As a result, if it is determined that the above condition is satisfied, then in step 710, B ₃ ≧ A> B
_It is determined whether or not ₂ holds. When such a condition is satisfied, it is determined that the number of operable times of the control valve 50 is one. In this case, after “1” is set to the counter C in step 712, the processing in step 720 is executed.

In step 710, B ₃ ≧ A>
If the B ₂ is determined not satisfied, step 714
It is further determined whether B ₂ ≧ A> B ₁ holds. When such a condition is satisfied, it is determined that the number of times of operation of the control valve 50 is two. In this case, step 71
After “2” is set in the counter in step 6, step 72
0 is executed.

In step 714, B ₂
If it is determined that ≧ A> B ₁ is not established, B ₁ ≧ A
Is satisfied, it is determined that the number of actuations of the control valve 50 is three. In this case, after “3” is set in the counter in step 718, the processing in step 720 is executed.

As described above, in this routine, the operable number of the control valve 50 is set in the counter C according to the stored value of the memory A. In the above step 708, if the stored value of the memory A is judged not to be B ₃ below, the processing of step 720 without setting the counter C is performed is executed.

In step 720, it is determined whether or not the XACIS flag has changed from off to on during the previous process to the present process. As a result, when it is determined that the state has changed from off to on, it is determined that the control valve 50 has been operated. In this case, the counter C indicating the number of times of operation is decremented in step 722,
Further, at step 724, the intake pressure PM at that time is stored in the memory A. As described above, the XASIC flag is turned on when the load on the internal combustion engine 12 is large, that is, when the intake pressure PM is high. Therefore, a large value is stored in the memory A. Therefore, thereafter, until the intake pressure PM is reduced to ₃ below again B, the condition of step 708 each time the routine is started is determined to be not established. In this case, XACI
Each time the S flag is turned on, the counter C is decremented.

At step 726, it is determined whether or not the value of the counter C is equal to or greater than "0". Counter C is
This is a counter that is decremented when the XACIS flag is turned on while the operable number of the control valve 50 is set and the intake pressure PM is maintained at a high pressure.
Therefore, as long as C ≧ 0 holds, it can be determined that the control valve 50 is in a state in which it can operate normally, and when C ≧ 0 is not established, the control valve 50 normally operates. It can be determined that there is a possibility that it cannot work. For this reason, in this routine, in step 726, C ≧ 0
Is satisfied, then, in step 728,
After the flag indicating that the update control of the highland learning value can be performed is set, the current routine ends. On the other hand, C
If ≧ 0 is not established, then, in step 730, a flag indicating that updating control of the highland learning value is impossible is set, and then the current routine is terminated.

As described above, according to the present embodiment, the number of times that the control valve 50 can be operated is set even if the internal combustion engine 12 is not returned to the idle state, and the operating state of the control valve 50 is set based on the number of times that the internal combustion engine 12 can be operated. Can be determined. For this reason,
According to the intake control apparatus for an internal combustion engine of the present embodiment, whether the control valve 50 is in the operable state or the inoperable state is more accurately than the first and second embodiments described above. Can be determined.

Next, a sixth embodiment of the present invention will be described. The intake control device for an internal combustion engine of this embodiment is the same as that shown in FIG.
Can be realized by the system configuration shown in FIG. In the fifth embodiment described above, the negative pressure level in the negative pressure tank 56 is estimated based on the intake pressure PM detected by the intake pressure sensor 49. The system of the present embodiment is characterized in that the negative pressure level in the negative pressure tank 56 is estimated based on the detection value of the air flow meter 58.

FIG. 16 shows an iso-negative pressure curve represented on coordinates where the horizontal axis is the engine speed NE and the vertical axis is the intake air amount GN. As shown in FIG. 16, the intake pressure PM of the internal combustion engine 12
Is determined almost uniquely with respect to the combination of the engine speed NE and the intake air amount GN. Therefore, by detecting GN and NE, it is possible to estimate the intake pressure PM generated in the surge tank 34. In this embodiment, E
The CU 10 executes the routine shown in FIG. 14 using the intake pressure PM estimated based on the intake air amount GN and the engine speed NE. According to this method, the same function as that of the fifth embodiment described above can be realized using the detection value of the air flow meter 58.

In the fifth and sixth embodiments, the ECU 10 executes the processing of steps 700 to 704 and step 724 so that the negative pressure estimating means according to claim 3 performs the processing of step 708. ~ 718
By executing the processing of (3), the operable number setting means of the third aspect executes the processing of the above steps 720 and 722, and the operation number counting means of the third aspect executes the processing of the steps 726 to 722. By executing the processing of 730, the operation availability determination means according to claim 3 is realized.

Next, a seventh embodiment of the present invention will be described. The intake control device for an internal combustion engine of this embodiment is the same as that shown in FIG.
In the system configuration shown in FIG. 17, this is realized by the ECU 10 executing the routine shown in FIG. FIG.
5 shows a flowchart of an example of a control routine executed by the ECU 10 to detect an operation failure of the control valve 50. The routine shown in FIG. 17 is a periodic interruption routine that is started every predetermined time.

When the routine shown in FIG. 17 is started, first, at step 800, the intake air amount GN calculated based on the detected value of the air flow meter 58 and the engine speed NE, and the equation (2) The calculated reference intake air amount GNTA (= tGNTAB * FTHA * KP
A ratio KENG = GN / GNTA with A) is calculated. As described above, when the control valve 50 operates normally, the reference intake air amount GNTA is determined by the throttle opening TA and the engine speed N.
This is the intake air amount estimated to be obtained for the combination with E. Therefore, as long as the control valve 50 is functioning normally, KENG always has a substantially constant value.

In step 802, it is determined whether the XASIC flag is on. As a result, XACIS
If it is determined that the flag is on, the process of step 804 is performed next. In step 804, an XACIS representing the state of the XACIS flag in the previous processing
It is determined whether or not the ISO flag is off. As a result, when it is determined that XACISO is off, it is determined that the XACIS flag has changed from off to on from the previous processing to the present processing, and then step 8
08 is executed. On the other hand, if it is determined that XACISO is not off, it is determined that the XACIS flag is continuously on, and steps 808 and 810 are executed.
Is jumped.

If it is determined in step 802 that the XACIS flag is not on, then step 8
Step 06 is executed. In step 806, an XACI indicating the state of the XACIS flag in the previous processing
It is determined whether or not the SO flag is on. As a result, when it is determined that the XACISO is on, it is determined that the XACIS flag has changed from on to off from the previous processing to the current processing, and then step 8
08 is executed. On the other hand, if it is determined that XACISO is not on, the XACIS flag is determined to be continuously off, and steps 808 and 810 are executed.
Is jumped.

According to the above processing, only when the XACIS flag changes from on to off or from off to on, that is, only when a command requesting a state change to the control valve 50 is issued. , The processing of step 808 is executed. In step 808, the above step 80
Deviation | KENG-K between KEN calculated at 0 and KENG (Kengo) calculated at the previous processing
It is determined whether or not ENGO | is equal to or greater than a predetermined determination value KFAIL.

As described above, as long as the control valve 50 is operating normally, KENG always takes a substantially constant value. Therefore, when the state of the XACIS flag changes, if the control valve 50 is operated following the change, | KENG-
KENGO | ≧ KFAIL does not hold. On the other hand, if the control valve 50 does not operate normally,
GN and GNTA are matched when the OFF command is issued, but GN and GNTA are not matched when the ON command is issued to the control valve 50.
Before and after the state of the CIS flag changes, a large change occurs in KENG. Therefore, in such a situation, | K
ENG-KENGO | ≧ KFAIL holds.

In this routine, step 80
If it is determined in step 8 that | KENG-KENGO | ≧ KFAIL holds, it is determined that the control valve 50 is not operating normally, and then the process of step 810 is executed. In step 810, the XACISF flag is turned on to indicate that the control valve 50 has malfunctioned. On the other hand, if it is determined in step 808 that the above condition is not satisfied, it is determined that the control valve 50 is operating normally, and step 810 is jumped. After the above processing is completed, KENG is stored as KENGO in step 812, and the contents of the XACIS flag are set in the XACISO flag in step 814. Then, the current routine ends. .

As described above, according to the system of this embodiment, it is possible to accurately determine whether the control valve 50 is operating based on the ratio between the actual intake air amount GN and the reference intake air amount GNTA. Can be. In the present embodiment, K
The operation state of the control valve 50 is determined based on whether or not a change exceeding a predetermined value has occurred in ENG = GN / GNTA. In other words, the above-described determination is performed based only on the amount of change of KENG, irrespective of the value of KENG itself. Therefore, variations in the initial characteristics of the internal combustion engine 12 and changes over time in the internal combustion engine 12 do not affect the determination accuracy. In this regard, the system according to the present embodiment includes the control valve 5
This has the advantage that a malfunction of 0 can be accurately and stably detected.

Next, an eighth embodiment of the present invention will be described. The intake control device for an internal combustion engine of the present embodiment can be realized by the system configuration shown in FIG. In the seventh embodiment described above, the actual intake air amount GN and the reference intake air amount G
The malfunction of the control valve 50 is detected based on the ratio with NTA. By the way, as described above, in the system configuration shown in FIG. 1, the actual intake pressure PM and the reference intake pressure PMTA
= TPMTAB * KPA (see the above equation (1)).

As described above, the reference intake pressure PMTA is an intake pressure estimated to be obtained for a combination of the throttle opening TA and the engine speed NE when the control valve 50 operates normally. Accordingly, PMTA and PM always have substantially the same value when the control valve 50 is functioning normally, and an ON command is issued to the control valve 50 in a situation where the control valve 50 does not operate normally. In this case, the values are greatly separated.

Therefore, the ratio between PM and PMTA is set to KEN.
If defined as G, KENG is always substantially constant under the condition that the control valve 50 normally operates, and under the condition that the control valve 50 does not operate normally, as in the case of the seventh embodiment. This is a variable that fluctuates greatly before and after a command requesting a state change is issued to the control valve 50. In the present embodiment, the ECU 10 determines the actual intake pressure PM and the reference intake pressure PM.
KENG calculated based on TA = PM / PMTA
Is used to execute the routine shown in FIG. According to such a method, using the detection value of the intake pressure sensor 49,
Functions similar to those of the above-described seventh embodiment can be realized.

In the systems of the first, second, fifth and sixth embodiments described above, the control valve 50 can be operated based on whether the negative pressure remains in the negative pressure tank 56 or not. It is determined whether the state is normal or inoperable. Therefore, for example, when the control valve 50 does not operate normally in a situation where an abnormality has occurred in the negative pressure tank 56 or the like and the negative pressure is estimated to remain in the negative pressure tank 56, There is a possibility that the operability is erroneously determined.

On the other hand, in the systems according to the seventh and eighth embodiments, the operating state of the control valve 50 is determined based on whether the control valve 50 is actually operating. Therefore, according to the systems of the seventh and eighth embodiments, when the control valve 50 cannot operate normally regardless of the cause, the abnormality can be reliably detected. In this regard, the systems of the seventh and eighth embodiments described above have superior detection accuracy with respect to the abnormality detection of the control valve 50 as compared with the first, second, fifth, and sixth embodiments. Will be.

In the seventh and eighth embodiments described above, the ECU 10 executes the processing of step 800, and the reference real relation detecting means according to claim 4 executes the processing of step 808. By doing so, the above-described operation state determination means is realized.

[0134]

As described above, according to the first aspect of the present invention, the number of times of operation of the negative pressure actuator after the predetermined negative pressure is introduced into the negative pressure tank, that is, the negative pressure tank Accurately determines whether or not the negative pressure actuator is operable based on whether or not the number of operable negative pressure actuators is determined by the capacity of the negative pressure actuator and the negative pressure consumption of the negative pressure actuator, etc. can do. Therefore, according to the intake control device for an internal combustion engine according to the present invention,
It is possible to accurately distinguish between a situation where the intake pipe length changes reliably and a situation where the intake pipe length may not change.

According to the second aspect of the present invention, the operating state of the control valve can be accurately determined based on whether or not at least one of the intake air amount and the intake pressure has changed due to a change in the state of the control valve. Can be detected. Therefore, according to the intake control apparatus for an internal combustion engine according to the present invention, it is possible to accurately distinguish between a state in which the intake pipe length changes in response to a command to the control valve and a state in which the intake pipe length does not change.

According to the third aspect of the present invention, the number of operable times of the negative pressure actuator is determined according to the load of the internal combustion engine.
It can be set to a value corresponding to the negative pressure actually stored in the negative pressure tank. Therefore, according to the intake control apparatus for an internal combustion engine according to the present invention, a state in which the intake pipe length changes and a state in which the intake pipe length does not change can be accurately distinguished according to the operating state of the internal combustion engine.

According to the present invention, the control valve operates properly based on at least one of the relationship between the reference intake air amount and the actual air amount and the relationship between the reference intake pressure and the actual air pressure. Can be determined. These relationships are almost constant as long as the control valve is operating normally without being affected by variations in characteristics of the internal combustion engine or changes in characteristics of the internal combustion engine due to aging. It shows a big change when it does not work. Therefore, according to the intake control device for an internal combustion engine according to the present invention,
It is possible to accurately distinguish between a state in which the intake pipe length changes and a state in which the intake pipe length does not change, without being affected by a characteristic error or the like of the internal combustion engine.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating a state of an intake system when a negative pressure actuator is turned on in a low rotation region of the internal combustion engine illustrated in FIG.

FIG. 3 is a cross-sectional view illustrating a state of an intake system when a negative pressure actuator is turned off in a high rotation region of the internal combustion engine illustrated in FIG. 1;

FIG. 4 is a characteristic diagram showing output characteristics of the internal combustion engine shown in FIG.

FIG. 5 is a diagram showing an example of an operation region of the control valve shown in FIG. 1;

FIG. 6 is a flowchart of an example of a highland learning value update routine executed in the electronic control unit shown in FIG. 1;

FIG. 7 is a flowchart of an example of an operation number counting routine executed in the first embodiment of the present invention.

FIG. 8 is a flowchart of an example of a learning execution determination routine executed in the first embodiment of the present invention.

FIG. 9 is a diagram showing another example of the operation region of the control valve shown in FIG. 1;

FIG. 10 is a system configuration diagram of another embodiment of the present invention.

FIG. 11 is a flowchart of an example of a highland learning value update routine executed in the electronic control unit shown in FIG. 10;

FIG. 12 is a flowchart of an example of a learning execution determination routine executed in a third embodiment of the present invention.

FIG. 13 is a flowchart of an example of a learning execution determination routine executed in a fourth embodiment of the present invention.

FIG. 14 is a flowchart of an example of a learning execution determination routine executed in a fifth embodiment of the present invention.

15 is a diagram showing a relationship between the level of negative pressure stored in the negative pressure tank shown in FIG. 1 and the number of times the control valve can be operated.

FIG. 16 is a diagram illustrating a relationship between an intake pressure and a combination of an engine speed and an intake air amount.

FIG. 17 is a flowchart of an example of a learning execution determination routine executed in a seventh embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 electronic control unit (ECU) 12 internal combustion engine 20 crank angle sensor 28 intake branch pipe 32 exhaust branch pipe 34 surge tank 36 intake pipe 40 throttle sensor 44 intake temperature sensor 48 exhaust recirculation control valve 50 control valve 52 negative pressure actuator 56 negative pressure Tank 58 Air flow meter GN Actual intake air amount GNTA Reference intake air amount PM Actual intake pressure PMTA Reference intake pressure

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Daisuke Yamada 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (58) Field surveyed (Int.Cl. ⁷ , DB name) F02B 27/02

Claims (4)

(57) [Claims] 1. A negative pressure tank for storing negative pressure of intake air of an internal combustion engine, and a negative pressure actuator that operates using the negative pressure stored in the negative pressure tank as a power source to change the length of an intake pipe of the internal combustion engine. In the intake control device for an internal combustion engine, a negative pressure introduction state detecting means for detecting a predetermined operation state in which a predetermined negative pressure is introduced to the negative pressure tank; and the predetermined operation state is detected by the negative pressure introduction state detection means. An actuation number counting means for counting the number of actuations of the negative pressure actuator after the operation is performed, and an act of judging that the negative pressure actuator is inoperable when the count value of the actuation number counting means exceeds a predetermined number. An intake control device for an internal combustion engine, comprising: availability determination means. 2. An intake control system for an internal combustion engine having a control valve for changing an intake pipe length of the internal combustion engine, wherein a change amount and an intake air amount generated in an intake air amount before and after a command requesting a state change of the control valve are issued. Change amount detecting means for detecting at least one of the change amounts occurring in the atmospheric pressure; and operation for judging that the control valve is malfunctioning when the detected value of the change amount detecting means is smaller than a predetermined value. An intake control device for an internal combustion engine, comprising: a state determination unit. 3. A negative pressure tank for storing an intake negative pressure of an internal combustion engine, and a negative pressure actuator that operates using the negative pressure stored in the negative pressure tank as a power source to change the length of an intake pipe of the internal combustion engine. An intake control device for an internal combustion engine, comprising: a negative pressure estimating means for estimating a negative pressure stored in the negative pressure tank based on a load of the internal combustion engine; and the negative pressure actuator according to an estimated value of the negative pressure estimating means. Number-of-operations setting means for setting the number of times of operation of the negative pressure actuator; number-of-times counting means for counting the number of times of operation of the negative pressure actuator after the number of times of operation is set by the number of times of operation; An internal combustion engine comprising: an operation availability determination unit configured to determine that the negative pressure actuator is in an inoperable state when a count value of the unit exceeds the number of times of operation. Intake control device. 4. An intake control system for an internal combustion engine having a control valve for changing an intake pipe length of the internal combustion engine, the relationship between a reference intake air amount corresponding to an operation state of the internal combustion engine and an actual intake air amount, and the internal combustion engine A reference actual relationship detecting means for determining at least one of a relationship between the reference intake pressure and the actual intake pressure corresponding to the operating state of the above-mentioned, and when the relationship detected by the reference actual relationship detecting device changes beyond a predetermined level, And an operating state determining means for determining that an operation failure has occurred in the control valve.