JP2001073789A - Supercharging pressure control system for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to surely restrain generation of smoke, by enabling to control air excess ratio accurately even in a case when it is affected by parameter according to altitude. SOLUTION: With the supercharging pressure control system for internal combustion engine equipped with turbocharger 9, target air excess ratio setting measure 52 sets target air excess ratio according to state of operation of the engine, and actual air excess ratio estimating measure 51 estimates actual air excess ratio with parameter depending on altitude based on actual state of operation of the engine, and supercharging pressure control measure 53 controls supercharging pressure so as to keep deviation between target air excess ratio and actual air excess ratio.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a supercharging pressure control device for an internal combustion engine having a turbocharger, and more particularly to a supercharging pressure control device for an internal combustion engine suitable for an internal combustion engine having a turbocharger with a variable nozzle vane. .

[0002]

2. Description of the Related Art In recent years, it has been required to develop an environmentally friendly environmental engine by reducing the emission of harmful substances such as CO _{2. In} order to make a diesel engine such an environmental engine, It is important to suppress the generation of smoke. To suppress the generation of this smoke,
For example, it is conceivable to perform intake pressure control. As a technique for controlling the intake pressure, for example, Japanese Patent Publication No. 3-24
There is a technique disclosed in Japanese Unexamined Patent Application Publication No. 937 (JP 1) and Japanese Patent Publication No. 61-201851 (JP 2).

Further, for example, in a vehicle equipped with a diesel engine, it is necessary to ensure a sufficient amount of intake air in order to suppress the generation of smoke at high altitudes. It has been proposed to provide a variable supercharging pressure intake system such as a turbocharger and control the supercharging pressure (in-manifold pressure) using such a system.

As a technique for controlling the supercharging pressure of a turbocharger in order to suppress the generation of smoke at high altitudes, Japanese Patent Laid-Open Publication No. Hei 6-288245 (Japanese Unexamined Patent Publication No. Hei 6-288245) discloses a technique.
There is a technology disclosed in US Pat.

[0005]

Incidentally, the generation of smoke is uniquely governed by the excess air ratio λ calculated based on the intake air amount (intake air weight flow rate). That is, if the amount of intake air corresponding to the amount of fuel injected into the cylinder is not ensured, the occurrence of smoke increases, which may be a limiting factor of the engine output.

The amount of intake air required to calculate the excess air ratio λ is not only affected by the supercharging pressure (intake manifold pressure), but also the atmospheric pressure and intake air temperature (intake manifold temperature when a turbocharger is provided). Since it is also affected by parameters corresponding to altitude such as volumetric efficiency indicating the suction characteristics of the engine, it is necessary to determine the intake air amount in consideration of these parameters. In particular, when the change in the intake air temperature (the intake manifold temperature) is large, the relationship between the intake air weight flow rate and the intake air pressure (the intake manifold pressure) in the speed density system does not hold. Is an important issue.

Here, the relationship between the atmospheric pressure and the temperature with respect to the altitude of the atmosphere is as shown in FIGS. 7 (A) and 7 (B). That is,
As shown in FIG. 7A, the relationship between the altitude of the atmosphere and the air pressure is such that the higher the altitude, the lower the air pressure. The relationship between atmospheric altitude and temperature is shown in FIG.
As shown in (B), there is a relationship that the temperature decreases as the altitude increases.

When the altitude increases and the atmospheric pressure decreases, the intake air mass flow rate of the engine decreases. On the other hand, when the altitude increases and the temperature decreases, the specific weight of air increases. I do. Here, assuming that the limit altitude at which the vehicle travels is about 4000 m, the rate of decrease in the intake air mass flow rate at the same altitude is plotted as the rate of decrease in the specific weight, as shown in FIG. 7C. In other words, since the intake air weight flow rate decreases at a rate of about 3 to 4% every 1000 m with respect to the altitude, if the fuel is injected without taking this into account, the excess air ratio at the high altitude is high. Is smaller than the excess air ratio, thereby increasing the amount of smoke generated.

On the other hand, at high altitudes where the atmosphere is sparse, even if an attempt is made to inject fuel to ensure engine output, the fuel cannot be injected due to the generation of smoke. For this reason, in order to suppress the generation of smoke particularly at high altitudes, the actual intake air amount is accurately calculated in consideration of the above-described parameter corresponding to the altitude, and the intake air amount is sufficiently secured. There is a need to.

[0010] On the other hand, in some cases, in supercharging pressure control, a correction is made based on the intake air temperature (intake manifold temperature).
It is not clear how the intake air temperature is corrected for the target supercharging pressure merely by performing the correction based on the intake air temperature correction coefficient. It is also conceivable to reduce the fuel injection amount in order to reduce the generation of smoke below the invisible smoke level. However, this reduces the engine output, which is not preferable for running the vehicle.

[0011] Further, in the above-mentioned publication 1, since the actual intake air amount at the present time cannot be obtained and the fuel injection amount with respect to the actual intake air amount cannot be calculated, the generation of smoke is reliably suppressed. I can't. In particular,
At high altitudes, although it is necessary to accurately calculate the actual intake air amount and set the fuel injection amount based on this based on which the smoke is not generated, this technology cannot accurately calculate the actual intake air amount Therefore, generation of smoke cannot be reliably suppressed.

The technique disclosed in the above-mentioned publication 2 is
The turbocharger does not perform supercharging pressure control to suppress the generation of smoke at high altitudes. In addition, although the correction is made by multiplying the atmospheric pressure correction value and the intake air temperature correction value,
In this case, the intake air density (specific weight) required for calculating the intake air amount cannot be accurately obtained. Further, the technique disclosed in the above-mentioned Publication 3 raises the intake pressure (in-manifold pressure) in order to reduce the generation of smoke.
The fact that the intake air amount changes depending on the intake air temperature (intake manifold temperature) is not taken into account at all, and therefore the intake air amount cannot be calculated accurately. difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has been made to enable accurate control of the excess air ratio even when affected by a parameter corresponding to altitude.
It is an object of the present invention to provide a supercharging pressure control device for an internal combustion engine, which can reliably suppress generation of smoke.

[0014]

According to a first aspect of the present invention, there is provided a supercharging pressure control apparatus for an internal combustion engine having a turbocharger, comprising: The setting means sets the target excess air ratio based on the operating state of the internal combustion engine, and the actual excess air ratio estimating means estimates the actual excess air ratio using a parameter corresponding to the altitude based on the operating state of the internal combustion engine. I do. The supercharging pressure control means controls the supercharging pressure so that the deviation between the target excess air ratio and the actual excess air ratio falls within a predetermined range.

Preferably, the actual excess air ratio estimating means includes an intake air temperature detecting means for detecting an intake air temperature, an atmospheric pressure detecting means for detecting an atmospheric pressure, an intake pressure detecting means for detecting an intake pipe pressure, and a rotational speed of the internal combustion engine. The actual excess air ratio (actual excess air ratio) is estimated based on the detection information from the rotational speed detecting means for detecting the excess air ratio. Preferably, the target excess air ratio setting means is configured to set the target excess air ratio based on detection information from a rotation speed detecting means for detecting a rotation speed of the internal combustion engine and a load sensor for detecting a load. .

[0016]

Embodiments of the present invention will be described below with reference to the drawings. A supercharging pressure control device for an internal combustion engine according to one embodiment of the present invention will be described with reference to FIGS. The internal combustion engine according to the present embodiment is configured as a direct injection type diesel engine (in-cylinder injection type internal combustion engine) 1, as shown in FIG.

In the diesel engine 1, an intake passage 3 and an exhaust passage 4 are connected to a combustion chamber 2 of the diesel engine 1. The communication between the intake passage 3 and the combustion chamber 2 is controlled by an intake valve 5.
The communication between the exhaust passage 4 and the combustion chamber 2 is controlled by an exhaust valve 6. Further, a fuel injection nozzle 7 is also provided so as to face the combustion chamber 2, and fuel is supplied to the fuel injection nozzle 7 from a fuel injection pump in accordance with an operating position of a rack controlled by a rack actuator (not shown). It has become so. The fuel injection device is
The present invention is not limited to the above-described one, but is a pressure-accumulation chamber fuel injection device (common rail type fuel injection device) configured to store high-pressure fuel in a pressure-accumulation chamber and inject the high-pressure fuel from a nozzle by switching control of an electromagnetic valve. There may be.

An intake throttle valve 8 is interposed in the intake passage 3. Then, by restricting the intake throttle valve 8, an EGR amount described later can be increased. Incidentally, the diesel engine 1 is provided with a turbocharger (turbocharger) 9. The turbocharger 9 has its exhaust turbine interposed in the exhaust passage 4,
A compressor connected to and driven by the exhaust turbine is interposed in the intake passage 3, and the driving force of the exhaust turbine is transmitted to the compressor so that the intake air is pressurized. An intercooler 10 is provided downstream of the compressor in the intake passage 3 in order to reduce the temperature of the air pressurized by the compressor.

Here, the turbocharger 9 is shown in FIG.
As shown in (A) and (B), a turbocharger with a variable nozzle vane (also referred to as a variable capacity turbocharger or VG turbo)
The nozzle vanes 9c are arranged at equal intervals around a turbine blade 9b of the exhaust turbine 9a. Each nozzle vane 9c is connected to an annular ring 9d, and when the annular ring 9d rotates in the direction of the arrow in the drawing, the angle of the nozzle vanes 9c, that is, the opening degree is changed. That is, the nozzle vane 9c
The supercharging pressure (in manifold pressure) decreases as the opening degree of the nozzle vane 9c decreases, and increases as the opening degree of the nozzle vane 9c decreases.

FIG. 3A shows a case where the opening of the nozzle vane 9c is fully opened. When the opening of the nozzle vane 9c is fully opened, the supercharging pressure (in-manifold pressure) becomes minimum. . On the other hand, FIG. 3B shows a case where the opening degree of the nozzle vane 9c is fully closed.
When the opening of c is fully closed, the supercharging pressure (in-manifold pressure) becomes maximum.

Here, as shown in FIGS. 2, 3A and 3B, a VG turbo actuator 11 is connected to the annular ring 9d. Here, the VG turbo actuator 11 is an actuator whose operation position can be variably controlled, and switches the supply state of air from the tank 12 into the control chamber 11a of the VG turbo actuator 11 by using the electromagnetic valves 13 and 14. Thus, the operating position is controlled. In addition, tank 1
2 is supplied with air from a vacuum pump.

The VG turbo actuator 11
Is not limited to such a configuration,
A device that can adjust the operating position stepwise may be used. Further, the VG turbo actuator 11 is not limited to an actuator that operates by supplying and discharging air, but may have another configuration as long as it is connected to the annular ring 9d to adjust the opening of the nozzle vane 9c. May be used.

The solenoid valves 13 and 14 are connected to a controller (ECU) 50 described later, and the operation thereof is controlled based on a control signal from the controller 50. That is, the operation of the solenoid valves 13 and 14 of the VG turbo actuator 11 is controlled based on a control signal from the controller 50 according to the operation state of the diesel engine 1.

The diesel engine 1 is also provided with an EGR device (exhaust gas recirculation device) 15 for recirculating a part of the exhaust gas discharged to the exhaust passage 4 to the intake passage. The EGR device 15 includes an exhaust gas recirculation passage (EGR passage) 15a provided to connect the intake passage 3 and an upstream side of the exhaust passage 4, and an EGR valve 15 attached to the EGR passage 15a.
b, and an EGR cooler 15c provided to reduce the temperature of the recirculated exhaust gas. In the present embodiment, the EGR valve 15b is not a simple on-off valve but a valve whose opening itself can be changed.

The EGR valve 15b is connected to the EGR actuator 16 and the operation of the EGR actuator 16 is controlled by a controller 50 described later, whereby the opening of the EGR valve 15b is adjusted and the EGR valve 15b is connected to the intake passage 3. The flow rate of the recirculated exhaust gas (hereinafter, referred to as EGR gas or recirculated gas) is adjusted.

Here, the EGR actuator 16 is
From the vacuum pump 17 to the control chamber 15b of the EGR valve 15b
Check the supply of air into a solenoid valve (solenoid valve)
The operation position is controlled by switching by 18a, 18b. The EGR actuator 16 is not limited to the one having such a configuration, and may be one that can adjust the operating position stepwise (for example, a stepper motor type). In addition, the EGR actuator 16 is not limited to an actuator that operates by supplying and discharging air, but may be an EGR actuator.
As long as the degree of opening of the valve 15b can be adjusted, another structure may be used.

The EGR actuator 16 is connected to a controller (ECU) 50 described later, and its operation is controlled based on a control signal from the controller 50. That is, based on the control signal from the controller 50 according to the operating state of the engine 1, the electromagnetic valves 18a,
The operation of 18b is controlled.

By the way, since the atmospheric pressure and the temperature decrease as the altitude increases (see FIGS. 7A and 7B), the intake pressure (boost pressure) and the intake temperature also decrease, and the volume efficiency is also affected. Therefore, it is difficult to calculate an accurate excess air ratio, and it is difficult to suppress the generation of smoke.
For this reason, in the present embodiment, the controller (ECU, ECU, or the like) controls the excess air ratio in consideration of these altitude-dependent parameters to suppress the generation of smoke at high altitudes.
As shown in FIG. 1, the electronic control unit 50 includes an actual excess air ratio estimating unit 51, a target excess air ratio setting unit 52, and a supercharging pressure control unit 53.

Here, the actual excess air ratio estimating means 51 estimates the actual excess air ratio (actual excess air ratio) λ1 based on the operating condition of the engine 1 using parameters corresponding to the altitude. That is, the actual excess air ratio estimating means 51
Is the intake manifold temperature [temperature of intake air in intake manifold (also referred to as intake manifold, intake temperature)] T _mani , intake manifold pressure (pressure of intake air in intake manifold, intake pressure) P
_mani, the atmospheric pressure P _a, based on the volumetric efficiency ηv to the engine rotational speed Ne and the engine rotational speed Ne, intake air quantity taken in the combustion chamber 2 (into the cylinder) is calculated (intake air weight flow rate) G _a , and calculates the actual excess air ratio λ1 from the intake air amount G _a.

[0030] for calculating the way the intake air amount G _a, intake manifold temperature T _mani, intake manifold pressure (gauge pressure) P
_mani, the atmospheric pressure P _a, by taking into account the volumetric efficiency .eta.v, are to be calculated more accurately the intake air amount G _a.
Since these parameters change according to the altitude, they are referred to as altitude-dependent parameters.
Therefore, the engine 1 includes an intake air temperature sensor (intake air temperature detection means) 31, an intake air pressure sensor (intake air pressure detection means) 32,
An atmospheric pressure sensor (atmospheric pressure detecting means) 33, a crank angle sensor 34, and the like are provided at predetermined locations. These sensors are connected to the controller 50, and detection signals from the sensors are sent to the actual excess air ratio estimating means 51 of the controller 50.

Since the engine speed Ne can be calculated based on the crank angle sensor 34, the crank angle sensor 34 is referred to as an engine speed sensor (engine speed detecting means, engine speed sensor) for convenience. Also,
The intake pressure sensor 32 is also called a boost pressure sensor (boost pressure detecting means). The intake pressure sensor 32 is attached to, for example, an intake manifold of the engine 1 and detects a pressure (boost pressure) of intake air pressurized by the turbocharger 9.

A load sensor 35 for detecting the load on the engine 1 is also provided.
Is also sent to the actual excess air ratio estimating means 51. As the load sensor 35, an accelerator opening sensor (APS) that detects the opening of an accelerator pedal (or the amount of depression of the accelerator) (not shown) is used.
Note that a rack position sensor that detects a rack position of a fuel injection pump (not shown) may be used as the load sensor 35.

The volume efficiency ηv is determined by the intake manifold temperature T
To change the _mani, the volumetric efficiency ηv regardless of the temperature change is simply the engine speed Ne treated as a constant, instead of obtaining the volumetric efficiency ηv to the engine load, the actual excess air rate estimating means 51, intake manifold temperature The influence of T _mani is also taken into account, and temperature correction is performed when obtaining the volume efficiency ηv. As a result, the intake air amount can be accurately calculated using the volume efficiency ηv determined accurately.

The actual excess air ratio estimating means 51 sets the reference intake manifold temperature to T0, sets the reference volumetric efficiency to the reference intake manifold temperature T0 to ηv0, and sets the volumetric efficiency index to m.
The volume efficiency ηv for an arbitrary intake manifold temperature T _mani is obtained by the following equation (1) for each engine speed Ne and engine load. ηv / ηv0 = (T _mani / T0) ^m (1) Specifically, first, for the target engine 1, the engine rotational speed Ne and the intake manifold temperature T for each engine load are set.
The characteristics between _mani and volume efficiency ηv are determined by bench tests.

FIG. 4 is a diagram showing an example of characteristics between the intake manifold temperature T _mani and the volume efficiency ηv. FIG. 4 is a graph in which the volume efficiency ηv with respect to a predetermined engine rotation speed Ne and an engine load is plotted for each intake manifold temperature T _mani , and the characteristics thereof are shown by a straight line. Also, the intake manifold temperature T
The change of the volumetric efficiency ηv with respect to the _mani is as shown in FIG. 4 regardless of the injection timing and the VG vane opening.

Next, a map for calculating the volume efficiency ηv is created based on the characteristics between the intake manifold temperature T _mani and the volume efficiency ηv. That is, the reference intake manifold temperature T0 is set for each engine speed Ne and engine load.
(For example, about 25 ° C.), a reference volume efficiency ηv0 is measured by a bench test, and this is compared with the engine speed Ne at the reference intake manifold temperature T0 (for example, about 25 ° C.), the engine load, and the reference volume efficiency ηv0. Create a volumetric efficiency map.

A characteristic indicating the relationship between the intake manifold temperature T _mani and the volumetric efficiency ηv is measured by a bench test for each engine rotation speed Ne and engine load, and based on this, each engine rotation speed Ne and engine load is measured. The volumetric efficiency index m is also determined for each of them, and is used as the reference intake manifold temperature T0 (for example, about 25).
C), a volume efficiency index map is created in which the engine speed Ne, the engine load, and the volume efficiency index m are associated with each other.

Then, a volume efficiency ηv with respect to an arbitrary intake manifold temperature T _mani , an engine rotation speed Ne, and an engine load.
Is calculated based on the reference intake manifold temperature T0 (for example, about 25 ° C.), the reference volumetric efficiency ηv0 obtained from the reference volumetric efficiency map, and the volumetric efficiency index m obtained from the volumetric efficiency index map. Next, _a method of calculating the intake air amount Ga by the actual excess air ratio estimating means 51 will be described.

The actual excess air ratio estimating means 51 calculates the following equation (2).
Temperature T represented by_mani, Intake manifold pressure P_mani
Using the equation for volumetric efficiency ηv defined in
G_a(Kg / s). ηv = 120G_a/ [Ne × Vh × γ_mani(P_mani, P_a, T_mani)] (2) where Ne is the engine speed and Vh is the engine speed.
Stroke volume, γ _mani(P_mani, P_a, T_mani) Is
Specific weight of air in intake manifold (kg / m^Three).

When the above equation (2) is modified, it is expressed as the following equation (3). Therefore, the actual excess air ratio estimating means 51 uses this equation (3) to calculate the intake air amount G _a Is calculated. G _a = _{[Ne × Vh × ηv × γ mani} (P mani, P a, T mani) ] / 120 (3) where specific weight _{γ mani (P mani, P a} , T mani) is intake manifold pressure (gauge pressure) to (kg / m ²⁾ and P _mani, atmospheric pressure (kg / m ²⁾ and P _a, the intake manifold temperature (K) as T _mani, represented by the formula (4). In addition, let the gas constant be R [kg · m / (kg · K)].

Γ _mani = (P _mani + P _a ) / (R × T _mani ) (4) Here, the engine stroke volume Vh and the gas constant R are constants, the engine speed Ne and the intake manifold pressure P _mani , Atmospheric pressure P _a , and intake manifold temperature T _mani use the values detected by the sensors, and the volumetric efficiency ηv uses the values determined in advance by the bench test as described above, using the intake air amount G
_a will be calculated.

[0042] Here, since the intake manifold pressure P _mani detected by the intake pressure sensor 32 is detected as the differential pressure between the atmospheric pressure to calculate the intake air amount G _a, detected by the atmospheric pressure sensor 33 It is also considered the atmospheric pressure P _a, which is. However, if configured by the absolute pressure sensor so as to detect the intake manifold pressure P _mani, there is no need to consider the atmospheric pressure P _a.

[0043] Then, the real excess air rate estimating means 51, and calculates the actual excess air ratio λ1 this manner the intake air amount G _a that is calculated. Here, the excess air ratio λ is the fuel injection amount (kg
/ S) is defined as Gf, and the theoretical air amount (kg / kg) required for completely burning 1 kg of fuel in theory is defined as L0.
It is represented by the following equation (5).

Λ = G _a / (L0 × Gf) (5) The fuel injection amount Gf is detected as an engine load by the engine speed detected by the engine speed sensor 34 and an engine load by the load sensor 35. Based on the accelerator pedal depression amount (accelerator opening), the engine speed is obtained from a fuel injection amount map in an engine load region.

The target excess air ratio setting means 52 operates the engine 1 (engine speed Ne, engine load).
The target excess air ratio λ0 is set based on
In other words, the target excess air ratio setting means 52 prepares for each engine rotation speed and each engine load area based on the detection information from the engine rotation speed sensor 34 and the load sensor 35 for detecting the load of the engine 1. Using the smoke characteristic (smoke characteristic indicating the relationship between excess air ratio λ and smoke R) as shown in FIG. 5, smoke (smoke density) R (%) is invisible smoke level R0.
Is set as the target excess air ratio λ0.

Here, the invisible smoke level R0 is
This is a reference value for the amount of exhaust gas harmful substances such as smoke, and is a limit smoke value at which the smoke amount becomes a visible smoke level when it exceeds this level. The invisible smoke level R0 is set, for example, as a ratio of about 15% of smoke. A target excess air ratio map in which the engine rotation speed, the engine load, and the target excess air ratio λ0 are associated with each other is prepared in advance, and the engine rotation speed sensor 34,
And a load sensor 35 for detecting the load of the engine 1
The target excess air ratio λ0 according to the engine rotational speed and the engine load range set based on the detection information from the ECU may be obtained from the target excess air ratio map.

The supercharging pressure control unit 53 sets the actual excess air ratio λ1 estimated by the actual excess air ratio estimation unit 51 by the target excess air ratio setting unit 52 in order to reduce the smoke R to the invisible smoke level R0 or less. Target excess air ratio λ
The supercharging pressure (in manifold pressure) is controlled so as to be 0 or more (see FIG. 5). Here, the boost pressure control means 53
Is the deviation Δλ (= λ1−λ) between the target excess air ratio λ0 set by the target excess air ratio setting means 52 and the actual excess air ratio λ1 estimated by the actual excess air ratio estimation means 51.
0) is calculated, and the supercharging pressure (in-manifold pressure) is controlled such that the deviation Δλ falls within a predetermined range.

The supercharging pressure control by the supercharging pressure control means 53 is performed by feedback control based on the excess air ratio of the opening degree of the nozzle vanes 9c of the turbocharger 9. The opening control of the nozzle vanes 9c of the turbocharger 9 is performed until the deviation Δλ between the actual excess air ratio λ1 and the target excess air ratio λ0 falls within a predetermined range, that is, until the deviation Δλ becomes smaller than the minute amount ε. .

When the deviation Δλ becomes smaller than the minute amount ε, the opening degree control of the nozzle vanes 9c of the turbocharger 9 is not performed because the control is performed within this range. This is to prevent the excess ratio λ1 from being smaller than the target excess air ratio λ0, which may cause the smoke to become larger than the invisible smoke level.

Specifically, the opening control of the nozzle vanes 9c of the turbocharger 9 is performed as follows. That is, when the deviation Δλ is negative, that is, the actual excess air ratio λ
If 1 is less than the target excess air ratio .lambda.0, since the intake air amount G _a is the smaller to meet the target excess air ratio .lambda.0, by increasing the supercharging pressure (intake manifold pressure) to increase the excess air ratio Nozzle vane 9c of turbocharger 9
Is controlled so as to reduce the opening degree (decrease the opening degree).

Meanwhile, when the deviation Δλ is positive, i.e. if the actual excess air ratio λ1 is greater than the target excess air ratio λ0 is opposite to the intake air amount G _a is too large to meet the target excess air ratio λ0 Therefore, in order to reduce the supercharging pressure (in-manifold pressure) and reduce the excess air ratio, control is performed to increase the opening degree of the nozzle vane 9c of the turbocharger 9 (expand the opening degree).

When the deviation Δλ is large, the supercharging pressure control means 53 increases the response of the control (increases the response),
By making it possible to sufficiently suppress the occurrence of smoke during transition,
In order to minimize the influence on the engine output, the following opening control of the nozzle vanes 9c of the turbocharger 9 is also performed. That is, when the magnitude of the deviation Δλ is equal to or larger than the predetermined value E (E> ε), the deviation Δλ changes the initial control amount of the opening degree of the nozzle vane 9c of the turbocharger 9 according to the magnitude. Has become. For example, when the magnitude of the deviation Δλ is equal to or larger than the predetermined value E (when the magnitude of the deviation Δλ is large), the initial control amount of the opening degree of the nozzle vane 9c of the turbocharger 9 is increased according to the deviation Δλ. In addition, a control for greatly reducing the opening of the nozzle vanes 9c of the turbocharger 9 (decreasing the opening) is performed.

In this case, the magnitude of the predetermined value E is changed depending on whether the deviation Δλ is a positive value or a negative value, that is, whether the actual excess air ratio λ1 is larger or smaller than the target excess air ratio λ0 ( For example, it is preferable to set the predetermined values E ₁ and E ₂ ). The supercharging pressure control device for an internal combustion engine as one embodiment of the present invention is configured as described above, and the operation of the supercharging pressure control by this device is performed as follows.

That is, as shown in FIG. 6, first, at step S10, the engine speed Ne and the engine load (for example, the accelerator opening) are read, and the routine proceeds to step S20, where the engine speed Ne and the engine load are calculated based on the engine speed Ne and the engine load. Using the smoke characteristics (smoke characteristics indicating the relationship between excess air ratio λ and smoke R) as shown in FIG. 5 prepared for each engine speed and engine load region, the smoke R (%) The excess air ratio λ at which the invisible smoke level R0 is set is set as the target excess air ratio λ0.

Next, at step S30, the intake pressure sensor 3
2, each of the detection value P _mani is detected by the atmospheric pressure sensor 33 and the intake air temperature sensor _31, P _a, loading a T _mani, the process proceeds to step S40, read intake air temperature T
_mani , a preset reference intake manifold temperature T0 (for example, about 25 ° C.), an engine rotation speed Ne, and a reference volumetric efficiency ηv obtained from a reference volumetric efficiency map according to the engine load.
Using the volume efficiency index m obtained from the volume efficiency index map according to 0, the engine rotation speed Ne, and the engine load, the volume efficiency ηv is obtained by the above equation (1).

[0056] Then, in step S50, the loaded intake manifold pressure P _mani, the atmospheric pressure P _a, the intake manifold temperature T _mani, using a gas constant R, which is set in advance, the specific weight gamma _mani by the formula (4) ( P _mani, P _a, seek a T _mani). Then, the specific weight γ thus obtained
_{mani (P mani, P a,} T mani), volumetric efficiency ηv obtained in step S40, the loaded engine speed N
e, Using the previously set engine stroke volume Vh, the intake air amount Ga is calculated by the above equation (3).

Next, in step S60, using the intake air amount Ga calculated in this manner, the fuel injection amount Gf set to obtain the desired output, and the theoretical air amount L0, the above equation ( The actual excess air ratio λ (actual excess air ratio λ1) is calculated by 5). Then, in step S70, the target excess air ratio λ0 is subtracted from the actual excess air ratio λ1, and the deviation Δλ between the actual excess air ratio λ1 and the target excess air ratio λ0 (= λ1-
λ0), and the process proceeds to step S80.

In step S80, it is determined whether the actual excess air ratio λ1 is larger or smaller than the target excess air ratio λ0, that is, whether the deviation Δλ is larger than zero. If it is determined that the difference Δ is also larger, the process proceeds to step S90, and it is further determined whether the deviation Δλ is within a predetermined range, that is, whether the deviation Δλ is smaller than the minute amount ε.

As a result of this determination, when it is determined that the deviation Δλ is equal to or more than the minute amount ε, the process proceeds to step S100, and whether or not the deviation Δλ is large, that is, the magnitude of the deviation Δλ is equal to a predetermined value E ₁ (E ₁ > ε) or not, and
As a result of this determination, when it is determined that the deviation Δλ is larger than the predetermined value E ₁ , the process proceeds to step S110, where the predetermined value E
The opening degree control for expanding the opening degree of the nozzle vanes 9c of the turbocharger 9 is rapidly performed according to the size of ₁ , and the routine returns.

[0060] On the other hand, in step S100, if the deviation Δλ is equal to or less than the predetermined value E _1, step S12
The control proceeds to 0, the opening control for increasing the opening of the nozzle vanes 9c of the turbocharger 9 is performed at a normal speed, and the routine returns. If it is determined in step S90 that the deviation Δλ is smaller than the small amount ε, the process proceeds to step S130, and returns without performing the opening control of the nozzle vanes 9c of the turbocharger 9.

By the way, at step S80, if it is determined that the deviation Δλ is less than or equal to 0, the process proceeds to step S140, the absolute value of the deviation Δλ is determined whether greater than a predetermined value E _2, the judgment result, if the absolute value of the deviation Δλ is determined to be greater than the predetermined value E _2, step S150
To proceeds, carried out by rapidly opening control to narrow the opening of the nozzle vane 9c of the turbocharger 9 in accordance with the magnitude of the predetermined value E _2, the process returns.

[0062] On the other hand, in step S140, if the absolute value of the deviation Δλ is equal to or less than the predetermined value E _2, the process proceeds to step S160, the opening control to narrow the opening of the nozzle vane 9c of the turbocharger 9 normal Perform at speed and return. Therefore, according to the supercharging pressure control device for the internal combustion engine, the actual excess air ratio λ1 is calculated using the parameter corresponding to the altitude, and the deviation Δλ between the actual excess air ratio λ1 and the target excess air ratio λ0 is determined by a predetermined value. The nozzle vane 9 of the turbocharger 9 is set within the range, that is, smaller than the minute amount ε.
Since the supercharging pressure (in-manifold pressure) is controlled by controlling the opening degree of c, the excess air ratio can be accurately controlled even in the case where the parameter is affected by the altitude. Accordingly, there is an advantage that the generation of smoke, soot, and the like can be surely suppressed and the smoke can be suppressed to the level of invisible smoke or less, and the exhaust gas characteristics can be improved.

[0063] Further, to perform the feedback control of supercharging pressure based on the excess air ratio lambda (intake manifold pressure), the intake air amount G _a is calculated accurately, the actual excess air ratio using the intake air amount G _a Since λ1 is calculated, control accuracy can be improved, and accordingly, generation of smoke, soot, and the like can be reliably suppressed, and there is an advantage that exhaust gas characteristics can be improved.

[0064] Further, the intake air amount G _a is calculated accurately, and calculates the actual excess air ratio λ1 using the intake air amount G _a, since it is possible to reliably suppress the occurrence of smoke or the like, there at high altitude Even so, the intake air amount can be reliably ensured, and fuel can be injected in accordance with the intake air amount, so that there is an advantage that the engine output characteristics can be sufficiently ensured. Further, when calculating the excess air ratio λ, the intake air temperature sensor 31,
It is only necessary to provide the intake pressure sensor 32 and the engine rotation speed sensor 34, and an expensive air flow meter need not be used.

In the above embodiment, the intake air amount G
_a is obtained by _a calculation formula or a map.
_a is, for example, Karman vortex flow meter, hot wire (hot wire)
What is detected by an air flow sensor (AFS) such as a flow meter may be used. In this case, the intake air amount G _a is
The detection value of the airflow sensor is Q (m ³ / s), and the specific weight of air in the airflow sensor unit is γ _sensor , which is calculated by the following equation (6).

G _a = Q × γ _sensor (6) where the specific weight γ _sensor is P in the above equation (4).
_{mani and} T _mani are obtained by setting the pressure P _sensor and the temperature T _sensor of the airflow sensor unit. For example, when a Karman vortex flowmeter is used, the measured value of the Karman vortex flowmeter is a volume flow. Must be calculated on the basis of the measured values of the temperature and the pressure in the above, but this is not different from the present embodiment. However, there is a disadvantage that it is difficult to select a mounting position of the Karman vortex generator.

On the other hand, when the hot wire flow meter is used, since the measured value of the hot wire flow meter is a weight flow rate, there is no disadvantage as in the above-mentioned Karman vortex flow meter, but the hot wire portion of the hot wire flow meter has dirt. However, there is a disadvantage that the accuracy is significantly reduced. Further, if the flow velocity distribution in the hot wire portion is not uniform, a measurement error occurs. Furthermore, since the introduction position of the blow-by gas is restricted from the viewpoint of contamination of the hot wire portion of the hot-wire flow meter, there is a disadvantage that the mounting of the hot-wire flow meter is greatly restricted.

However, if mounting is possible under such restrictions, the supercharging pressure (in-manifold) may be used in combination with the air flow sensor to adjust the excess air ratio λ so that the smoke becomes less than the invisible smoke level. Pressure) can also be controlled. In the above-described embodiment, the supercharging pressure (in-manifold pressure) is adjusted by using the turbocharger with a variable nozzle vane to control the excess air ratio λ. However, the supercharging pressure (in-manifold pressure) can be adjusted. Anything is fine. For example, the supercharging pressure may be adjusted using a turbocharger having a wastegate valve or a supercharger with a transmission.

In the above embodiment, the present invention is described as applied to a diesel engine.
If supercharging pressure control is performed while detecting knock by a knock sensor, the present invention can be applied to a gasoline engine (in particular, a direct injection type).

[0070]

As described above in detail, according to the supercharging pressure control apparatus for an internal combustion engine of the present invention, the actual excess air ratio is calculated using the parameters corresponding to the altitude, and the actual excess air ratio and the target air ratio are calculated. Since the supercharging pressure (in manifold pressure) is controlled so that the deviation from the excess ratio is within a predetermined range, the excess air ratio can be accurately controlled even in the case where the parameter is affected by the altitude, Thereby, there is an advantage that generation of smoke can be surely suppressed and exhaust gas characteristics can be improved.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a supercharging pressure control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a schematic diagram showing an overall configuration of a boost pressure control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 3 is a schematic view showing a turbocharger with a variable nozzle vane provided in the internal combustion engine according to one embodiment of the present invention, wherein (A) shows a case where the nozzle vane opening is fully opened;
(B) shows the case where the nozzle vane opening is fully closed.

FIG. 4 is a diagram illustrating an example of a change in volumetric efficiency with respect to an intake manifold temperature in the supercharging pressure control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 5 is a diagram showing smoke characteristics with respect to an excess air ratio in the supercharging pressure control device for the internal combustion engine according to one embodiment of the present invention.

FIG. 6 is a flowchart illustrating a supercharging pressure control in a supercharging pressure control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 7 shows general atmospheric pressure, air temperature, intake air reduction rate,
It is a figure which shows the relationship with altitude, (A) shows the relationship between altitude and barometric pressure, (B) shows the relationship between altitude and temperature, (C) shows the relationship between altitude and the intake air amount reduction ratio, respectively. I have.

[Explanation of symbols]

Reference Signs List 9 turbocharger 9c nozzle vane 31 intake air temperature sensor (intake air temperature detecting means) 32 intake air pressure sensor (intake air pressure detecting means, boost pressure sensor) 33 atmospheric pressure sensor (atmospheric pressure detecting means) 34 engine rotational speed sensor (engine rotational speed detecting means) ) 35 Load sensor (accelerator opening sensor) 50 Controller (ECU) 51 Actual excess air ratio estimating means 52 Target excess air rate setting means 53 Supercharging pressure control means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G005 DA02 EA04 EA16 FA35 GA04 GB24 GC04 GC07 GD25 GE01 GE09 HA04 HA12 HA19 JA13 JA24 JA32 JA39 JA43 JA45 JA51 JB02 JB05 3G084 AA01 BA05 BA08 BA13 BA20 DA10 EB08 EB11 FA01 FA02 FA08 FA08 FA12 FA13 FA25 FA33 FA38

Claims (1)

[Claims] 1. A supercharging pressure control device for an internal combustion engine having a turbocharger, comprising: a target excess air ratio setting means for setting a target excess air ratio based on an operation state of the internal combustion engine; Actual excess air ratio estimating means for estimating the actual excess air ratio using a parameter corresponding to the altitude based on the altitude, and supercharging the deviation so that a deviation between the target excess air ratio and the actual excess air ratio falls within a predetermined range. A supercharging pressure control device for an internal combustion engine, comprising: supercharging pressure control means for controlling pressure.