JPH0941981A - Supercharging pressure control device for internal combustion engine with supercharger - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To supercharge pressure of an internal combustion engine with a supercharger capable of reliably maintaining a closed state of a wastegate valve even when intake pressure is increased by controlling an opening area of a variable nozzle. Provide a control device. A negative pressure generated in a vacuum pump 111 driven by an internal combustion engine is applied to a wastegate valve actuator 114 while an amount of exhaust gas flowing into an exhaust turbine 107 is controlled by a variable nozzle 109 in a low rotation speed range. Then, the waste gate valve 110 is forcibly closed.
Therefore, the variable nozzle 109 is adjusted to adjust the exhaust turbine 107.
The wastegate valve 110 is prevented from being opened even when the exhaust gas flow rate flowing into the engine is increased to increase the boost pressure, and the effect of increasing the boost pressure by the variable nozzle is sufficiently exerted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a supercharging pressure control system for an internal combustion engine with a supercharger, and more particularly to a supercharging pressure control system for an internal combustion engine with a supercharger equipped with a variable nozzle and a wastegate valve.

[0002]

2. Description of the Related Art In recent years, many automobile internal combustion engines are equipped with a supercharger in order to increase the intake efficiency and increase the output of the internal combustion engine. In an internal combustion engine equipped with a supercharger, when the internal combustion engine speed and output increase and the exhaust gas flow rate increases, the intake pressure becomes too high and knocking occurs, or the cylinder pressure becomes excessive. In order to prevent the rise, it is known to install a wastegate valve that controls the exhaust gas flow rate that bypasses the exhaust gas turbine for driving the supercharger.

Further, in order to increase the exhaust gas inflow speed to the exhaust turbine and increase the intake pressure even in an operating state where the internal combustion engine has a low rotational speed, the opening area of the exhaust gas inlet of the exhaust gas turbine is made variable. It is also known to install a variable nozzle (see Japanese Patent Laid-Open No. 61-40415). That is, in an operating state in which the amount of exhaust gas is small, the variable nozzle is controlled so that the opening area is small, the flow velocity of exhaust gas is increased, the turbine speed is increased to increase the intake pressure, and the opening is increased as the amount of exhaust gas is increased. Greatly control the area.

Therefore, it is desirable to keep the wastegate valve closed in a range where knocking does not occur or within the cylinder pressure limit in an operating state where the exhaust gas amount is small. In addition, as a method of driving the wastegate valve, the intake air at the outlet of the supercharger is used as a driving force, and the intake air amount supplied to the actuator of the wastegate valve is controlled by a solenoid valve whose duty ratio is controlled to supply the intake air amount. It is common to increase the opening degree of the wastegate valve as the number increases.

[0005]

Therefore, when the opening area of the variable nozzle is controlled to increase the intake pressure in the low rotational speed range, the exhaust gas pressure upstream of the exhaust turbine rises and the exhaust gas acts on the wastegate valve. The gas pressure also increases. Therefore, the wastegate valve cannot be maintained in the closed state, and part of the exhaust gas is discharged without flowing into the turbine, so the area of the variable nozzle is controlled and the effect of accelerating the flow velocity is fully exerted. Can not do it.

The present invention has been made in view of the above problems, and it is possible to reliably maintain the closed state of the wastegate valve even when the intake pressure is increased by controlling the opening area of the variable nozzle. An object of the present invention is to provide a supercharging pressure control device for an internal combustion engine with an engine.

[0007]

According to a first aspect of the present invention, there is provided a supercharging pressure control device for an internal combustion engine with a supercharger, which comprises an inflow area changing means for changing an exhaust gas inflow area into an exhaust turbine, and an exhaust gas upstream of the exhaust turbine. Bypass exhaust gas amount changing means for changing the amount of exhaust gas that branches off from the gas flow path and bypasses the exhaust turbine, and supercharging pressure by the inflow area changing means until the exhaust gas inflow area to the exhaust turbine becomes maximum. Is controlled to a target boost pressure determined according to the operating state of the internal combustion engine, and the low revolution range control means for forcibly closing the bypass exhaust gas amount changing means, and the exhaust gas inflow area to the exhaust turbine is maximized. After that, the bypass exhaust gas amount changing means controls the supercharging pressure to a target supercharging pressure determined according to the operating state of the internal combustion engine.

In this supercharging pressure control device, the exhaust gas pressure is reduced by forcibly closing the bypass exhaust gas amount changing means within a range where the inflow area can be controlled by the inflow area varying means. To prevent. A supercharging pressure control device for an internal combustion engine with a supercharger according to claim 2, wherein the transmission has two or more shift patterns, and the low rotation speed range control means and the high rotation speed range control means are two or more transmissions. And two or more target supercharging pressure patterns according to the gear shift pattern.

In this supercharging pressure control device, the supercharging pressure is controlled to an appropriate pressure corresponding to the operating state of the internal combustion engine by changing the target supercharging pressure according to the shift pattern.

[0010]

1 is a block diagram of a supercharging pressure control device for an internal combustion engine with a supercharger, in which intake air sucked from an air cleaner 101 is supplied to a compressor 103 via an intake pipe 102. . The intake air pressurized by the compressor 103 is supplied to the diesel engine 105 via the intercooler 104.

Exhaust gas discharged from the diesel engine 105 drives the exhaust gas turbine 107 through the exhaust manifold 106 and is discharged to the outside from the exhaust pipe 108.
The rotary shaft of the exhaust gas turbine 107 is directly connected to the compressor 103. At the inlet of the exhaust gas turbine 107, a variable nozzle 109 for varying the flow passage area and a waste gate valve 110 for bypassing the exhaust gas to the exhaust pipe 108 are installed.

The opening of the variable nozzle 109 is controlled by a variable nozzle actuator 112 which uses a negative pressure generated by a vacuum pump 111 driven by the diesel engine 105 as a drive source. The negative pressure supplied to the variable nozzle actuator 112 is the variable nozzle solenoid valve 113.
Adjusted by Further, the opening degree of the wastegate valve 110 is controlled by a wastegate valve actuator 114 which normally uses compressed air generated in the compressor 103 as a drive source, but the vacuum pump 111 is used to forcibly close the wastegate valve 110. The negative pressure generated at is introduced.

The waste gate valve actuator 11
The four-way solenoid valve 115 for switching the drive source of No. 4 and the amount of compressed air supplied to the wastegate valve actuator 114 are adjusted by the wastegate valve solenoid valve 116. The variable nozzle solenoid valve 113, the four-way solenoid valve 115, and the waste gate valve solenoid valve 116 are operated by an operation signal output from the control unit 120.

FIG. 2 is a flowchart of a control routine executed by the controller 120. In step 21, the internal combustion engine operating state quantity, that is, the throttle valve opening θ, the rotation speed Ne, and the intake pressure of the intake manifold of the compressor 103 are shown. Read Pb. In step 22, a reference value is calculated, and in step 23, it is determined whether or not the variable nozzle 109 is in the fully open state. Whether or not the variable nozzle 109 is fully open can be determined by whether or not the reference opening VNs of the variable nozzle, which will be described later, is a predetermined value (for example, 95%) or more. .

That is, if VNs ≦ 95%, it is not fully open. If VNs> 95%, it is determined to be fully open. When a negative determination is made in step 23, that is, when the variable nozzle 109 is not fully opened, the process proceeds to step 24, the low rotation speed range control process is executed, and this control routine is ended.

When the affirmative determination is made in step 24, that is, when the variable nozzle 109 is in the fully open state, the process proceeds to step 25, the high rotation speed range control processing is executed, and this control routine is ended. FIG. 3 is a flowchart of the reference value calculation processing executed in step 22 of the control routine, and in step 22a, the reference opening VNs of the variable nozzle is calculated as a function of the rotation speed Ne.

VNs = VNs (Ne) In step 22b, the reference opening WGBs of the wastegate valve is calculated as a function of the rotation speed Ne. WGVs = WGVs (Ne) Further, at step 22c, the target intake pressure Pt is calculated as a function of the rotation speed Ne and the throttle valve opening degree θ, and this processing is ended.

Pt = Pt (Ne, θ) FIG. 4 is a flowchart of the low rotation speed range control processing executed in step 24 of the control routine.
At a, it is determined whether the actual intake pressure Pb is lower than the target intake pressure Pt. If an affirmative decision is made in step 24a, that is, if Pt> Pb, the routine proceeds to step 24b, where the opening VN of the variable nozzle is calculated based on the following equation.

VN = VNs + ΔVN Here, ΔVN is a predetermined constant value. If a negative determination is made in step 24a, that is, if Pt ≦ Pb, the process proceeds to step 24c, and the opening VN of the variable nozzle is calculated based on the following equation. VN = VNs-ΔVN In step 24d, the opening VN of the variable nozzle is output, and in step 24e, a forced closing command is output to the waste gate valve 110, and this processing ends.

FIG. 5 is a flowchart of the high rotation speed range control processing executed in step 25 of the control routine.
In step 25a, it is determined whether the actual intake pressure Pb is lower than the target intake pressure Pt. If a positive determination is made in step 25a, that is, if Pt> Pb, step 25
Proceeding to b, the opening WGV of the waste gate valve is calculated based on the following equation.

WGV = WGVs + ΔWGV Here, ΔWGV is a predetermined constant value. If a negative determination is made in step 25a, that is, if Pt ≤ Pb, the process proceeds to step 25c, and the wastegate valve opening degree WGV
Is calculated based on the following equation. WGV = WGVs-ΔWGV In step 25d, the waste gate valve opening degree WGV
Is output and the processing is terminated.

FIG. 6 is a system diagram around the waste gate valve and the four-way solenoid valve. (A) shows the waste gate valve 11
When 0 is forcibly closed, (b) shows when the wastegate valve 110 is in control. That is, the waste gate valve actuator 114 is partitioned by the diaphragm 114a into a spring chamber 114b and an air chamber 114c.

A spring 114d is installed in the spring chamber 114b and urges the diaphragm 114a toward the air chamber 114c. The 4-way solenoid valve 115 has four ports 115
a, 115b, 115c and 115d are installed, and the connection is switched between the ports depending on whether the solenoid 115e is energized or de-energized.

The port 115a is connected to the compressor 103 outlet for taking in intake air, the port 115b is connected to the waste gate valve actuator 114, and the port 115c is connected to the vacuum pump 111 for introducing negative pressure. The port 115d is open to the atmosphere. Solenoid 1
When 15e is excited, the ports 115a and 115d are in communication with each other, and the ports 115c and 115b are in communication with each other, as shown in (a).

Therefore, by sucking the diaphragm 114a toward the air chamber 114c by the negative pressure generated by the vacuum pump 111, the waste gate valve 110 is reliably maintained in the closed state. When the solenoid 115e is de-energized, the ports 115a and 115b are in communication with each other, and the ports 115c and 115d are in communication with each other, as shown in (B).

Therefore, the opening of the wastegate valve 110 is controlled by the intake air supplied through the wastegate valve electromagnetic valve 116. The duty ratio of the variable nozzle solenoid valve 113 is controlled by the variable nozzle opening VN output from the control unit 12, and the opening of the variable nozzle 109 is controlled. Similarly, the wastegate valve opening WGV output from the control unit 12 controls the duty ratio of the wastegate valve electromagnetic valve 116, and the opening of the wastegate valve 110 is controlled.

In a vehicle equipped with a brake compressor such as a large truck, the wastegate valve 110
In order to forcibly close the valve, positive pressure may be supplied to the spring chamber 114b side of the waste gate valve 114. Also,
Instead of the 4-way solenoid valve, the supercharging pressure-atmospheric pressure supply path and the negative pressure-atmospheric pressure supply path may be independently communicated with the air chamber 114c, and a 3-way solenoid valve may be provided for each.

FIG. 7 is an explanatory view of the effect of the supercharging pressure control device for an internal combustion engine with a supercharger according to the first claim, in which the horizontal axis represents the internal combustion engine speed Ne and the vertical axis represents the flow into the exhaust turbine. Exhaust pressure Pe is set. The broken line shows the case of the conventional supercharging pressure control device, and when the exhaust pressure Pe becomes high in the rotational speed range in which the waste gate valve 110 is closed, the waste gate valve 110 is shown.
Was opened, and the exhaust pressure Pe was prevented from further increasing.

The solid line is the case of the supercharging pressure control device according to the first aspect of the present invention, and the waste gate valve 110 is forcibly closed by the negative pressure, so that the exhaust pressure Pe can be sufficiently increased. Further, in recent years, an increasing number of automobiles are capable of switching the shift pattern of the transmission with a switch, for example, between a power mode and an economy mode.

In addition to the power mode and economy mode, a snow mode for facilitating traveling on a snowy road or a transfer L4 mode for lowering the gear ratio for facilitating climbing and descending of a four-wheel drive vehicle is provided. There are also cars. When the shift pattern of the transmission is switched in this way, it is necessary to switch the control patterns of the variable nozzle 109 and the waste gate valve 110 accordingly.

FIG. 8 is a flow chart of a control pattern changing routine. In step 801, it is determined whether the internal combustion engine speed Ne is equal to or higher than a predetermined threshold value Ni, that is, whether the internal combustion engine is not idling. If an affirmative decision is made in step 801, the operation proceeds to step 802,
It is determined whether the throttle valve opening θ is equal to or greater than a predetermined threshold value θf, that is, whether the internal combustion engine output is required.

If an affirmative decision is made in step 802, the routine proceeds to step 803, where the shift pattern is transfer L4.
Determine if it is in mode. When an affirmative decision is made in step 803, the routine proceeds to step 804, where the variable nozzle and waste gate valve are controlled in a pattern corresponding to the transfer L4 mode.

Next, in step 805, when the variable nozzle is not fully opened, negative pressure is supplied to the wastegate valve actuator to forcibly close the wastegate valve. When a negative determination is made in step 803, the process proceeds to step 806, and it is determined whether the shift pattern is the power mode.
If a positive determination is made in step 806, step 807
And proceeds to step 805 by controlling the variable nozzle and waste gate valve in a pattern corresponding to the power mode.

When a negative determination is made in step 806, the process proceeds to step 808, and it is determined whether the shift pattern is in the normal mode. When an affirmative decision is made in step 808, the operation proceeds to step 809, the variable nozzle and the waste gate valve are controlled in a pattern corresponding to the normal mode, and the operation proceeds to step 805.

When a negative determination is made in step 808, the process proceeds to step 810, and it is determined whether the shift pattern is the snow mode. When the affirmative determination is made in step 810, the process proceeds to step 811, the variable nozzle and the wastegate valve are controlled in a pattern corresponding to the snow mode, and the process proceeds to step 812 to release the forced closing of the wastegate valve. This is because it is not necessary to actively increase the output of the internal combustion engine,
Rather, it is required to improve fuel economy.

When a negative determination is made in step 810, the process proceeds to step 813, the variable nozzle and the waste gate valve are controlled in a pattern corresponding to the economy mode, and the process proceeds to step 812 to cancel the forced closing of the waste gate valve. When a negative determination is made in step 801 or 802, the process directly proceeds to step 812.

FIG. 9 is a control pattern diagram of the variable nozzle and the wastegate valve, in which the horizontal axis represents the number of revolutions and the vertical axis represents the variable nozzle opening and the wastegate valve opening. As described above, by changing the control pattern of the variable nozzle and the waste gate valve in accordance with the shift pattern, it becomes possible to obtain the supercharging characteristic more suitable for the shift pattern.

[0038]

In the supercharging pressure control device for the internal combustion engine with a supercharger according to the first aspect of the present invention, the bypass exhaust gas amount changing means is forced within the range in which the inflow area can be controlled by the inflow area varying means. By closing the valve, a part of the exhaust gas can bypass the exhaust turbine and escape, so that a desired boost pressure can be obtained.

In the supercharging pressure control device for an internal combustion engine with a supercharger according to a second aspect of the present invention, the target supercharging pressure is changed according to the shift pattern to obtain the supercharging pressure suitable for the shift pattern. Is possible.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a supercharging pressure control device for an internal combustion engine with a supercharger.

FIG. 2 is a flowchart of a control routine.

FIG. 3 is a flowchart of a reference value calculation process.

FIG. 4 is a flowchart of a low rotation speed range control process.

FIG. 5 is a flowchart of a high rotation speed range control process.

FIG. 6 is a system diagram around a wastegate valve and a 4-way solenoid valve.

FIG. 7 is an explanatory diagram of an effect of the supercharging pressure control device for the internal combustion engine with a supercharger according to the first claim.

FIG. 8 is a flowchart of a control pattern changing routine.

FIG. 9 is a control pattern diagram of a variable nozzle and a waste gate valve.

[Explanation of symbols]

 103 ... Compressor 105 ... Internal Combustion Engine 107 ... Exhaust Turbine 109 ... Variable Nozzle 110 ... Wastegate Valve 112 ... Variable Nozzle Actuator 113 ... Variable Nozzle Solenoid Valve 114 ... Wastegate Valve Actuator 115 ... 4-Way Solenoid Valve 116 ... Wastegate Valve Electromagnetic Valve 12 ... Control unit

Claims (2)

[Claims] 1. An inflow area changing means for changing an exhaust gas inflow area to an exhaust turbine, and a bypass exhaust gas for changing an amount of exhaust gas which branches from an exhaust gas flow path upstream of the exhaust turbine and bypasses the exhaust turbine. Until the exhaust gas inflow area into the exhaust turbine reaches the maximum, the inflow area changing means controls the supercharging pressure to the target supercharging pressure determined according to the operating state of the internal combustion engine, and After the exhaust gas inflow area to the exhaust turbine reaches the maximum, the low rotation speed range control means for forcibly closing the exhaust gas amount changing means and the bypass exhaust gas amount changing means operate the supercharging pressure to operate the internal combustion engine. A supercharging pressure control device for an internal combustion engine with a supercharger, comprising: a high rotation speed range control means for controlling a target supercharging pressure determined according to a state. 2. A transmission having two or more shift patterns, and the low rotation speed range control means and the high rotation speed range control means have two or more targets corresponding to two or more shift patterns of the transmission. A supercharging pressure control device for an internal combustion engine with a supercharger according to claim 1, comprising a supercharging pressure pattern.