JPS6143221A - Control device of engine with exhaust turbosupercharger - Google Patents

Abstract

PURPOSE:To prevent an engine from generating abnormality of its combustion, by increasing the size of an exhaust gas introducing passage to a turbine and improving combustibility of the engine by a decrease of exhaust pressure, when the engine at its cold time is driven in high load operation and knocking is generated. CONSTITUTION:If knocking is detected by a knocking sensor 29, a control device opens a selector valve 18 in no relation to the operating condition of an engine 1. If the knocking is not detected, the control device, closing the selector valve 18 in a low speed range of the engine 1, introduces exhaust gas to a turbine 9 only from a low speed exhaust gas introducing passage 16. The control device, opening the selector valve 18 in a high speed range of the engine, introduces the exhaust gas to the turbine 9 from the both exhaust gas introducing passages 16, 17.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention includes an exhaust turbo supercharger for supercharging intake air, and the diameter of the exhaust gas introduction passage to the turbine of the exhaust turbo supercharger is This invention relates to an engine equipped with a diameter variable means that varies the diameter according to engine operating conditions.

[Prior art] Conventionally, the diameter of the exhaust passage upstream of the turbine is switched between large and small depending on engine operating conditions such as engine speed and load, and when the engine is operating at low speed, the passage diameter is set to the "small" side. The turbo is set to narrow the exhaust gas to increase the inflow speed of the exhaust gas to the turbine, and by rotating the turbine at high speed, boost pressure is quickly increased, improving the engine's output performance in the low speed range. A supercharged engine is known (Utility Model Application No. 56-16113)
(See Publication No. 9).

In an engine having such a structure, the turbocharging efficiency can be improved by improving the turbine output in a low speed range, and accordingly, the output performance of the engine can be improved.

However, in a low speed range, since the diameter of the exhaust gas introduction passage is narrowed down, the exhaust pressure on the upstream side of the turbine rapidly increases as the engine speed increases. This increase in exhaust pressure becomes a major factor that inhibits engine combustibility, such as an increase in the amount of internal EGR (the amount of exhaust gas that remains in the combustion chamber), and causes knocking and roughness (
This leads to problems such as combustion abnormalities such as misfires.

[Object of the Invention] An object of the present invention is to provide a turbocharged engine equipped with a means for varying the diameter of the exhaust gas introduction passage to the turbine, in the event of engine combustion abnormality or when combustion abnormality may occur. An object of the present invention is to provide a control device for a turbocharged engine that can effectively deal with operating conditions.

[Structure of the Invention] Therefore, in the present invention, the engine combustion abnormality occurs or during specific operation such as during operation with a high probability of occurrence, more specifically, when engine knocking or roughness occurs, The basic feature is that during cold engine high load operation, the diameter of the exhaust gas introduction passage to the turbine is forcibly increased even if the engine operating state is such that the diameter of the exhaust gas introduction passage to the turbine should be reduced.

[Effects of the Invention] According to the present invention, since the passage diameter of the exhaust gas introduction passage to the turbine is increased during the above-mentioned specific operation, the exhaust pressure upstream of the turbine can be reduced, and the reduction in exhaust pressure causes It is possible to improve the combustibility of the engine, to reliably prevent engine combustion abnormalities, and to prevent torque shock and deterioration of emissions due to combustion abnormalities.

[Example] Examples of the present invention will be described in detail below.

As shown in FIG. 1, the engine 1 includes an intake passage 5 which is opened and closed with respect to a combustion chamber 4 by an intake valve 2 and an exhaust valve 3.
and an exhaust passage 6, and when the turbine 9 is driven by the exhaust gas flowing down the exhaust passage 6, the blower lO is driven in conjunction with this, and the blower lO is The intake air pressurized by
It has a basic structure in which so-called intake air supercharging is performed by supplying air to the air.

An air cleaner 11 is installed in the intake passage 5 on the upstream side of the blower 10, and an air flow meter 12 is installed downstream of the air cleaner 11 to measure the amount of intake air from moment to moment. Further, a throttle valve 13 is provided downstream of the blower 10 in the intake passage 5 and is opened and closed depending on the load of the engine 1, and a fuel injection valve 14 is provided downstream of the throttle valve 13.

On the other hand, the exhaust passage 6 is partitioned into a low-speed exhaust gas introduction passage 16 and a high-speed exhaust gas introduction passage 17 by a partition wall 15 at the exhaust introduction port of the turbine 9. The upstream side is opened and closed on and off by a switching valve 18, which is a diameter variable means according to the present invention. Furthermore, a catalytic exhaust gas purification device 19 is interposed in the exhaust passage 6 downstream of the turbine 9.

A waste gate passage 20 is opened in the low-speed exhaust gas introduction passage 16 and bypasses the turbine 9 to bypass a part of the exhaust gas to the exhaust passage 6 downstream of the turbine 9. 21, the supercharging pressure is controlled so that the supercharging pressure does not exceed a preset maximum supercharging pressure, as described below.

Furthermore, the exhaust passage 6 between the turbine 9 and the catalytic exhaust gas purification device 19 and the intake passage 5 downstream of the throttle valve 13 are exhaust gas recirculation passages (hereinafter simply referred to as EGR passages).
an exhaust gas recirculation control valve (hereinafter referred to as an EGR valve) 2 that is connected to the EGR passage 22 and is interposed in the EGR passage 22;
3 is opened, part of the exhaust gas is recirculated to the intake side, and as is well known, the inert recirculated exhaust gas suppresses an excessive increase in the maximum combustion temperature of the engine and reduces NOx. Suppress outbreak.

The above waste gate valve 21. Regarding the switching valve 18°, the spark plug 24 installed in the combustion chamber 4, the fuel injection valve 14, etc. that are directly or indirectly involved in the combustibility of the engine 1, as described in detail below, the computer 25 installed in the vehicle Control is performed by

This computer 25 includes the intake air amount detected by the air flow meter 12, the engine rotation speed detected by the rotation speed sensor 26, and the boost pressure or load detected by the pressure sensor 27 installed in the intake passage 5 downstream of the throttle valve 13. and a knock sensor 29 that detects the exhaust pressure detected by the pressure sensor 28 installed in the exhaust passage 6 downstream of the turbine 9, and also the knocking of the engine l.
Using the combustion abnormality detected by as basic data, in addition to opening/closing control of the switching valve I8, fuel control of the fuel injection valve I4, ignition advance control of the ignition plug 24, etc. are executed.

The switching valve I8 is basically opened and closed by a diaphragm type switching actuator 30 whose operation source is the exhaust pressure in the upstream portion of the turbine of the exhaust passage 6 in which the switching valve 18 is installed.

A first control valve 32 whose opening and closing are controlled by the computer 25 is interposed in the middle of the exhaust pressure introduction passage 31 that introduces exhaust pressure to the switching actuator 30. The first pressure chamber 30a of the switching actuator 30 is opened.
When exhaust pressure is applied to the diaphragm 30b, the diaphragm 30b pushes the actuating rod 30c, one end of which is fixed to the diaphragm 3ob, in the direction of arrow A in the figure against the spring force of the coil spring 30d, and the switching valve 18 is activated via the link mechanism 30f. Operate open. In addition, the second pressure chamber 3 of the switching actuator 3°
0e, a negative pressure introduction passage 33 having a negative pressure outlet is communicated with the intake passage 5 of the throttle valve I3, and a second control valve whose opening/closing is controlled by the computer 25 is provided in the middle of this negative pressure introduction passage 33. 34 are interposed.

This negative pressure introduction passage 33 and the second control valve 3
4, as will be described in detail below, when the exhaust pressure is not high enough to open the switching actuator 30, such as when the engine is operating at low speed and low load, the throttle valve summer 3 is closed downstream. This is to ensure that the switching actuator 30 is opened by introducing the intake negative pressure into the second pressure chamber 30e.

Note that the opening and closing of the waste gate valve 21 is performed by the blower lO.
This is done by a diaphragm type wastegate actuator 35 which uses the discharge pressure of A relief passage 37 communicating with is provided, and a control valve 38 for controlling the amount of relief is interposed in the middle of this relief passage 37. This control valve 38 is controlled by the computer 25, and when the exhaust pressure detected by the pressure sensor 28 installed in the exhaust passage 6 attempts to rise beyond a set value, the control valve 38 is closed. The relief passage 37 is closed, the boost pressure of the blower 10 is applied through the boost pressure introduction passage 36, the waste gate valve 21 is opened, and part of the exhaust gas is passed through the waste gate passage 20 to the turbine 9.
bypass and prevent excessive increase in boost pressure.

Next, a control method for the switching valve I8, which is a feature of the present invention, will be explained.

As shown in FIG. 2, when the computer 25 starts controlling the switching valve I8 with the start of operation of the engine 1, first, in step 101,
The presence or absence of knocking is determined by the knock sensor 29. When knocking is detected, in step 102, the switching valve 18 is forcibly opened regardless of the operating state of the engine l. In this case, the computer 25 controls the exhaust pressure introduction passage 31. An opening operation command is simultaneously output to both control valves 32 and 34 provided in the negative pressure introduction passage 33, respectively, and the first pressure chamber 30 of the switching actuator 30 is opened.
By introducing the exhaust pressure upstream of the turbine 9 into a and the intake negative pressure downstream of the throttle valve 13 into the second pressure chamber 30e, the switching actuator 30 is reliably opened and the switching valve 18 is opened. As a result, the passage diameter of the exhaust gas introduction passage (16, 17) to the turbine 9 is expanded, and the exhaust gas is introduced into the turbine 9 through the expanded passage diameter, and the exhaust pressure upstream of the turbine 9 is increased. rapidly declining,
Combustibility is improved and subsequent knocking is prevented.

On the other hand, in an operating state in which knocking does not occur, it is determined in step 103 whether or not the switching valve 18 is in a region where it should be closed (closed region).

For example, as shown in Fig. 3, this judgment is made as a closed area until the exhaust pressure Pe, which increases with the engine speed, reaches the set exhaust pressure PeO, and an open area where the exhaust pressure Peo increases beyond the set exhaust pressure PeO. I will do it as. This set exhaust pressure Peo is the value of the exhaust pressure corresponding to the engine rotation speed of 3.00 Orpm on the exhaust pressure rising line when the engine is fully opened, for example, 200 m
Set to mHg.

If it is determined in step 103 that the operating state of engine l is in the closed region, step 10
At step 4, the switching valve 18 is operated to close. For this purpose, a first . The second control valves 32 and 34 may be turned off. The switching actuator 30 closes the switching valve 18 by the spring force of a built-in coil spring 30d. By closing the switching valve 18, the exhaust gas flows into the turbine 9 only through the low-speed exhaust gas introduction passage I6 at an increased flow rate, improving the turbine output and ensuring an improvement in supercharging efficiency by the blower IO. In other words, it performs supercharging in the low speed range to improve engine output.

On the other hand, during high-speed operation when the exhaust pressure Pe downstream of the turbine 9 rises above the set exhaust pressure Peo, the switching valve 8 is opened in step 102. In this case, since the exhaust pressure upstream of the turbine 9 is also sufficiently high, the first control valve 32 is simply opened by the computer 25, and the switching actuator 30 opens the switching valve 18.
It works like opening.

From then on, the low-speed and high-speed exhaust gas introduction passages 16
．． A large amount of exhaust gas is sent to the turbine 9 from both of the turbines 17 to drive the turbine 9 at high speed, and the intake air is pressurized by the blower 10 to the boost pressure required at high speeds (high load) to ensure high output.

In the above embodiment, the presence or absence of knocking is simply detected by the knock sensor 29, but for example,
A water temperature sensor that detects engine cooling water temperature and an intake passage 5
In combination with the pressure sensor 27 provided in the exhaust passage 6 and the pressure sensor 28 provided in the exhaust passage 6, it is possible to detect operating times where there is a high probability of combustion abnormality occurring in the engine 1, such as during high load operation when the engine is cold. The switching valve 18 may be forcibly opened during such specific operation.

Further, in the above embodiment, the exhaust gas introduction passage to the turbine 9 is divided into two exhaust gas introduction passages 16. for low speed and high speed.
17, and the passage diameter is switched by opening and closing the high-speed exhaust gas introduction passage 17 with a switching valve 18. However, the present invention provides a low-speed turbo supercharger having a relatively small diameter exhaust gas introduction passage. and a high-speed turbo supercharger having a relatively large-diameter exhaust gas introduction passage, and the low-speed turbo supercharger is exclusively used at low speeds,
Needless to say, this method can also be applied to engines that use a dedicated high-speed turbocharger or use both turbochargers at high speeds.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an engine according to a seventh embodiment of the present invention, FIG. 2 is a flow chart showing a switching valve opening/closing control method, and FIG. 3 is a graph showing a closed region and an open region of the switching valve. DESCRIPTION OF SYMBOLS 1... Engine, 5... Intake passage, 6... Exhaust passage, 7... Turbo supercharger, 9... Turbine, 10...
・Blower, 14...Fuel injection valve, 16.1
7...Low speed and high speed exhaust gas introduction passage, I8...Switching valve, 24...Spark plug, 25...Computer, 29...Knock sensor, 30.
Switching actuator, 3I/exhaust pressure introduction passage, 32...control valve.

Claims (1)

[Claims] (1) An exhaust turbo supercharger for supercharging intake air is provided, and a diameter variable means is provided to vary the diameter of the exhaust gas introduction passage to the turbine of the exhaust turbo supercharger depending on the engine operating state. 1. A control device for an engine equipped with an exhaust turbo supercharger, characterized in that during a specific operation of the engine, the diameter variable means increases the diameter of the exhaust gas introduction passage regardless of the operating state of the engine.