JPH0415954Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine equipped with an exhaust turbocharger for supercharging intake air.

(Prior Art) An exhaust turbo supercharger aims to improve engine filling efficiency and engine output by supercharging intake air using the pressure of engine exhaust gas. Patent application filed by a person first
As described in the specification of No. 59-161980, the exhaust gas introduction passage to the exhaust turbine of the exhaust turbocharger is formed by first and second passage parts arranged in parallel, and at high speed, Exhaust gas flows through both the first and second passage sections, but at low speeds, a control valve is used to close the second passage section at its inlet and allow exhaust gas to flow only through the first passage section. A so-called twin engine that increases the flow rate of exhaust gas into the exhaust turbine at low speeds and rotates the exhaust turbine at high speed to quickly increase boost pressure and improve engine output performance at low speeds.・An engine with a scroll-type exhaust turbocharger has been proposed.

Figure 2 shows the main parts of the intake and exhaust passages of the above-mentioned engine with a twin scroll exhaust turbo supercharger. It's a supercharger. 9
1 is a turbine, and 10 is a compressor driven by the turbine 9 to supercharge the air in the intake passage 5 and supply it to the engine. turbine 9
The exhaust gas introduction passage 8 is partitioned into a first passage part 16 and a second passage part 17 by a partition wall 15, and the exhaust passage 6a upstream of the turbine 9 has a second passage part 17. A control valve 18 as an exhaust passage switching mechanism is provided at the inlet position.
This control valve 18 is closed in a state substantially perpendicular to the flow of exhaust gas in order to ensure sealing performance against exhaust gas when the control valve 18 is closed, and its opening direction is opposite to the flow of exhaust gas. It is arranged in such a manner that it is in the direction of When the engine is running at low speeds, the control valve 18 closes the inlet of the second passage section 17 to allow exhaust gas to flow only to the first passage section 16, and when the engine is running at high speeds, the control valve 18 is opened to allow the exhaust gas to flow. It is configured to flow into both the first and second passage portions 16,17. Furthermore, an upstream end portion of an exhaust bypass passage 20 that bypasses the turbine 9 and bypasses a portion of the exhaust gas to the exhaust passage 6d downstream of the turbine 9 is opened in the first passage portion 16 for low speed, By opening and closing this passage 20 with a waste gate valve 21, the supercharging pressure is controlled so that the supercharging pressure does not exceed a preset maximum supercharging pressure.

By the way, in the turbocharged engine configured as described above, as the engine speed increases, the waste gate valve 21 first opens, and then the second high-speed passage portion of the exhaust gas introduction passage 8 opens. The control valve 18 provided at the inlet of the waste gate valve 17 is controlled by a computer to open, but from the time the waste gate valve 21 opens until the engine speed reaches a predetermined speed, the control valve 18 controls the flow of exhaust gas. Since the control valve 18 is closed almost at right angles to the exhaust passage 6a, this control valve 18 creates exhaust resistance, and as a result, the exhaust pressure upstream of the control valve 18 suddenly increases as the engine speed increases. It will rise.

This increase in exhaust pressure increases pumping loss and increases the amount of internal EGR (the amount of exhaust gas that remains in the combustion chamber), which inhibits combustion in the engine and reduces output. Summer. Further, since the control valve 18 is configured to open in a direction opposite to the flow of exhaust gas, a large operating force is required to open the control valve 18.

(Purpose of the invention) Therefore, the purpose of the invention is to provide a configuration in which the exhaust gas introduction passage to the turbine has a passage portion for low speed and a passage for high speed, and is equipped with a control valve for switching between these passages. An object of the present invention is to provide an engine with an exhaust turbo supercharger which prevents an increase in exhaust pressure in an exhaust passage upstream of a control valve when the control valve is closed and a wastegate valve is opened.

(Structure of the invention) The present invention provides an exhaust bypass passage that bypasses the turbine and is provided with a waste gate valve that opens before the exhaust passage switching control valve opens the second passage portion. The exhaust passage switching control valve is characterized in that it is provided in such a manner that it opens into the exhaust passage at a position upstream of the exhaust passage switching control valve.

(Effect of the invention) According to the invention, since the upstream end of the exhaust bypass passage that bypasses the turbine is opened upstream of the control valve of the exhaust passage, the opening of the exhaust bypass passage brings it into a closed state. Since it is possible to prevent a sudden increase in exhaust pressure in the exhaust passage upstream of a certain control valve, it is possible to prevent a decrease in engine output due to this increase in exhaust pressure. There is also the advantage that less actuation force is required to open the control valve, which is closed approximately at right angles to the flow of exhaust gas.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to FIG.

In FIG. 1, an engine 1 includes an exhaust turbo supercharger disposed astride an intake passage 5 and an exhaust passage 6, which are opened and closed with respect to a combustion chamber 4 by an intake valve 2 and an exhaust valve 3, respectively. 7, and when the turbine 9 is driven by the exhaust gas introduced from the exhaust gas introduction passage 8, the compressor 10 is driven in conjunction with this, and this compressor 10
The intake air pressurized by the combustion chamber 4 is supplied to the combustion chamber 4 for supercharging.

An air cleaner 11 is disposed in the intake passage 5a on the upstream side of the compressor 10, and an air flow meter 12 for measuring the amount of intake air from moment to moment is disposed downstream of the air cleaner 11. Further, a throttle valve 13 is provided in the intake passage 5b on the downstream side of the compressor 10, and is opened and closed according to the load of the engine, and a fuel injection valve 14 is further arranged downstream of the throttle valve 13.

The exhaust gas introducing passage 8 to the turbine 9 in the exhaust passage 6a is partitioned into a first passage part 16 and a second passage part 17 by a partition wall 15, and the second passage part 17 is located upstream of the first passage part 16 and the second passage part 17. It is designed to be opened and closed by a control valve 18 provided on the side. In its closed state, the control valve 18 is substantially perpendicular to the flow of exhaust gas, and its opening direction is opposite to the flow of exhaust gas. Further, a catalytic exhaust gas purification device 19 is provided in the exhaust passage 6b downstream of the turbine 9. The exhaust passage 6 is provided with an exhaust bypass passage (wastegate passage) 20 that bypasses the turbine 9.
a opens at a position upstream of the control valve 18, and by controlling the opening and closing of this exhaust bypass passage 20 with a waste gate valve 21, the boost pressure exceeds a preset maximum boost pressure. The boost pressure is controlled to avoid high pressure.

On the other hand, the exhaust passage 6b between the turbine 9 and the exhaust gas purification device 19 and the intake passage 5b downstream of the throttle valve 13 are an exhaust gas recirculation passage (hereinafter referred to as EGR).
This EGR
When the exhaust gas recirculation valve (hereinafter referred to as the EGR valve) 23 provided in the middle of the passage 22 is opened, part of the exhaust gas is recirculated to the intake side, and the inert recirculated exhaust gas is used to cool the engine. This suppresses the excessive rise in the maximum combustion temperature of No. 1 and suppresses the generation of NO _x . Note that 24 is a spark plug arranged facing the combustion chamber 4.

The operations of the waste gate valve 21, exhaust gas introduction passage switching control valve 18, spark plug 24, fuel injection valve 14, etc. are controlled by a computer 25, which is detected by the air flow meter 12. intake air amount, engine rotation speed detected by rotation speed sensor 26,
The intake pressure detected by the pressure sensor 27 disposed in the intake passage 5 downstream of the throttle valve 13, the exhaust pressure detected by the pressure sensor 28 disposed in the exhaust passage 6b downstream of the turbine 9, Using the water temperature detected by the water temperature sensor 29 installed in the cooling waterway as basic data, in addition to opening/closing control of the waste gate valve 21 and control valve 18, fuel control of the fuel injection valve 14 and ignition advance angle of the ignition plug 24 are performed. Executes control, etc.

The opening and closing of the control valve 18 is basically
This is performed by a diaphragm type switching actuator 30 whose operation source is the exhaust pressure of the upstream portion of the turbine in the exhaust passage 6a in which the exhaust passage 6a is installed. A first control valve 32 that is controlled to open and close by the computer 25 is provided in the middle of the exhaust pressure introduction passage 31 that introduces exhaust pressure to the switching actuator 30. When actuated and exhaust pressure acts on the first pressure chamber 30a of the switching actuator 30, the diaphragm 3
0b pushes the actuating rod 30c, one end of which is fixed to the diaphragm 30b, in the direction of arrow A in the figure against the spring force of the coil spring 30d, thereby opening the control valve 18 via the link mechanism 30f. Further, a negative pressure introduction passage 33 having a negative pressure outlet in the intake passage 5b downstream of the throttle valve 13 is communicated with the second pressure chamber 30e of the switching actuator 30.
A second control valve 34 whose opening and closing are controlled by a valve 5 is provided.

The wastegate valve 21 is opened and closed by a diaphragm wastegate actuator 35 which uses the discharge pressure of the compressor 10 as a driving source.
In the middle of the pressure introduction passage 36 that leads the discharge pressure to the
A relief passage 37 communicating with the intake passage 5a upstream of the compressor 10 is provided, and a control valve 38 for controlling the amount of relief is provided in the middle of the 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 is about to rise beyond a set value, the control valve 38 is closed. It operates to close the relief passage 37 and open the pressure introduction passage 3.
6, the discharge pressure of the compressor 10 is applied to open the waste gate valve 21, and a part of the exhaust gas is passed through the exhaust bypass passage 20 to the turbine 9.
is bypassed to prevent excessive increase in boost pressure.

In the embodiment of the exhaust turbocharged engine according to the present invention described above, the waste gate valve 21 first opens as the engine speed increases, and then the second high-speed valve of the exhaust gas introduction passage 8 opens. The computer 25 controls the passage switching control valve 18 provided at the entrance of the passage section 17 to open, but as described above, the upstream end 20a of the exhaust bypass passage (wastegate passage) 20 is connected to the exhaust passage 6a. Since the exhaust passage 6a on the upstream side of the control valve 18 in the closed state is opened on the upstream side of the control valve 18, when the waste gate valve 21 opens, the exhaust passage 6a on the upstream side of the control valve 18 in the closed state is connected to the downstream side of the turbine 9 through the exhaust bypass passage 20. communicates with the side low-pressure exhaust passage 6b,
Therefore, a sudden increase in exhaust pressure on the upstream side of the control valve 18 is prevented, a decrease in engine output can be prevented, and the control valve 18 can be opened smoothly with a smaller operating force.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram of an engine according to an embodiment of the present invention, and FIG. 2 is a sectional view showing a main part of an intake and exhaust passage of a conventional engine with an exhaust turbo. 1... Engine, 5... Intake passage, 6... Exhaust passage, 7... Exhaust turbo supercharger, 8... Exhaust gas introduction passage, 9... Turbine, 10... Compressor, 16... Exhaust gas introduction 17: a first passage portion of the passage 8; 17: a second passage portion of the exhaust gas introduction passage 8; 18: a control valve; 20: an exhaust bypass passage; 21: a waste gate valve.

Claims (1)

[Claims for Utility Model Registration] An exhaust turbo supercharger for supercharging intake air is provided, and an exhaust gas introduction passage to a turbine of the exhaust turbo supercharger is formed by first and second passage portions. and an exhaust turbo supercharger provided in the exhaust passage in such a manner that the control valve closes the second passage portion at low speed and opens the second passage portion at high speed, and opens in a direction opposite to the flow of exhaust gas. an exhaust bypass passage that bypasses the turbine and includes a wastegate valve that opens before the control valve opens the second passageway portion;
An engine with an exhaust turbo supercharger, characterized in that an upstream end thereof opens into the exhaust passage at a position upstream of the control valve.