JPH07208187A - Turbo-supercharged engine - Google Patents

Abstract

PURPOSE:To provide a turbo-supercharged engine in which the suction air is compressed by the compressor of a turbocharger, and the energy of the excessive discharge gas when a waste gate valve is opened, in a high speed and a high load area, can be recovered. CONSTITUTION:A power turbine 22 is provided on the downstream of a waste gate valve 21, to be connected in parallel to the exhaust gas turbine 12 of a main turbocharger 11, and its output is made to return to the output shaft 23 of the diesel engine 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbocharged engine, and more particularly to a turbocharged engine in which exhaust gas of the engine drives an exhaust turbine of a turbocharger and the compressor of the turbocharger compresses intake air. .

[0002]

2. Description of the Related Art In addition to improving engine output,
In particular, a turbocharged engine is widely used in order to effectively use the energy of exhaust gas. A turbocharged engine drives its exhaust turbine with exhaust gas, and compresses intake air with a compressor that is directly connected to this exhaust turbine to fill more intake air into the engine. Equipped with a turbocharger having such an exhaust turbine, it is possible to improve the output of the engine by effectively utilizing the energy of the exhaust gas.

[0003]

In such a turbocharged engine, when the engine speed gradually increases, the exhaust turbine is also driven at high speed, and the intake pressure of the engine rises excessively. Further, the rotational speed of the turbocharger is excessively increased, intake air is supplied to the engine more than necessary, and the pressure in the cylinder is excessively increased. In order to prevent such excessive rotation of the turbocharger and excessive rise of pressure in the cylinder, a wastegate valve is provided.If the intake pressure rises excessively, open the wastegate valve and exhaust the exhaust gas. The gas is allowed to escape through the wastegate valve, and the supply of exhaust gas to the turbocharger is suppressed.

As described above, in the conventional turbocharged engine, when the wastegate valve for controlling the intake pressure is installed, the exhaust gas escaped by the wastegate valve is directly guided to the exhaust pipe, It was thrown into the atmosphere. That is, when the exhaust gas is released by the wastegate valve, the exhaust gas is not effectively used, which causes a problem that fuel consumption is deteriorated particularly in the high speed / high load region of the engine.

The present invention has been made in view of the above problems, and aims to effectively utilize the energy of exhaust gas in the high speed / high load region where the wastegate valve is opened. It is an object of the present invention to provide a turbocharged engine designed to improve fuel efficiency.

[0006]

According to the present invention, an exhaust gas of an engine is driven by an exhaust turbine of a turbocharger, and a compressor of the turbocharger compresses intake air. Of the exhaust gas of the turbocharger so as to release the exhaust gas when the engine speed exceeds a predetermined speed or the engine speed exceeds a predetermined engine speed; The present invention relates to a turbocharged engine including an output shaft and a power turbine that is driven by exhaust gas that is transmitted through the wastegate valve.

[0007]

Therefore, when the intake pressure exceeds the predetermined pressure or the engine speed exceeds the predetermined speed, the wastegate valve is opened and the exhaust gas is supplied to the power turbine through the wastegate valve. It Therefore, the energy of the exhaust gas is recovered through the power turbine, and the energy of the surplus exhaust gas can be recovered particularly in the high speed / high load region.

[0008]

1 and 2 show a turbocharged engine according to a first embodiment of the present invention, in which an engine body 10 made of a diesel engine is equipped with a turbocharger 11. The turbocharger 11 is composed of an exhaust turbine 12 and a compressor 13, which are directly connected to each other by a rotary shaft 14. The compressor 13 compresses the intake air taken in through the air cleaner 15, and an intercooler 16 is connected to the downstream side thereof so as to cool the intake air compressed by the intercooler 16.

A wastegate valve 21 is connected in the middle of the exhaust pipe of the engine body 10 and upstream of the exhaust turbine 12 of the turbocharger 11.
An actuator 20 for opening and closing the waste gate valve 21 is provided. The actuator 20 is, for example, an air actuator having a diaphragm, and is configured to extract intake air pressure from between the compressor 13 and the intercooler 16 of the turbocharger 11 and operate it.

Further, this engine has a power turbine 22.
Is equipped with. The power turbine 22 is the engine body 10.
Gear 2 meshing with gear 24 fixed to the output shaft 23 of
5 and the fluid coupling 26 via the fluid coupling 26, and is for recovering the energy of the exhaust gas when the waste gate valve 21 is opened.

In the above-described structure, when the engine body 10 is operated, its exhaust gas is supplied to the exhaust turbine 12 of the turbocharger 11, and this turbine 12
To drive. Therefore, through the rotary shaft 14, the compressor 1
3 is rotationally driven, and the intake air taken in by the air cleaner 15 is compressed. And the compressed intake air is the intercooler 1
It is cooled by 6 and supplied to each cylinder through the intake manifold of the engine body 10.

When the intake pressure on the output side of the compressor 13 becomes high in the high speed / high load region of the engine, this intake pressure is supplied to the actuator 20 and the diaphragm is pushed to open the waste gate valve 21. When the wastegate valve 21 is opened, the engine body 10
At least a part of the exhaust gas discharged from the exhaust gas is supplied to the power turbine 22 through the wastegate valve 21 without being supplied to the exhaust turbine 12. Therefore, the turbocharger 11 gradually decreases its operation, and the power turbine 22 is driven instead. The output of the power turbine 22 is the fluid coupling 26.
And the output shaft 2 of the engine 10 via the gears 25, 24.
3 and is superimposed on the output of the engine 10.

As described above, in the diesel engine according to this embodiment, the power turbine 22 is provided downstream of the wastegate valve 21 so as to be arranged in parallel with the exhaust turbine 12 of the main turbocharger 11, and the output thereof is set to the diesel engine 10. The output shaft 23 is returned to. When the waste gate valve 21 is opened for supercharging pressure control, excess exhaust gas drives the power turbine 22, and the energy of the exhaust gas is recovered.

In the conventional diesel engine with a wastegate valve, deterioration of fuel consumption in the high speed / high load region where the wastegate valve 21 operates has been a problem. In this embodiment, the power turbine 22 recovers the surplus exhaust gas energy from the wastegate valve that has been conventionally exhausted, thereby improving the fuel efficiency in the high speed / high load region.

FIG. 2 shows the improvement of fuel consumption in such a high speed / high load region. When the engine speed exceeds a predetermined value and the waste gate valve is opened,
It is clearly shown that the power consumption rate of the power turbine 22 improves the fuel consumption rate, which has been deteriorated in the past. In this graph, the vertical axis represents the net fuel consumption rate (BSFC Br
ake specific fuel consump
section).

Next, a second embodiment will be described with reference to FIG. In this embodiment, the ECU 32 controls the operation of the air actuator 20 for opening and closing the waste gate valve 21 in order to perform the operation more accurately. The actuator 20 that controls the opening and closing of the wastegate valve 21 is connected to the air tank 30, and a solenoid valve 31 is connected in the middle of the air pipe thereof, and the solenoid valve 31 receives the signal from the rotation detection sensor 33. It is controlled by.

When the engine speed is equal to or lower than the predetermined speed, the wastegate valve 21 is closed as described above, and the engine operates as a normal turbocharged engine. That is, the exhaust gas drives the exhaust turbine 12 of the turbocharger 11, and the compressor 13 directly connected to the exhaust turbine 12 compresses the intake air.

The rotation speed of the engine body 10 is detected by the rotation detection sensor 33, and when the ECU 32 detects that the rotation speed of the engine 10 exceeds a predetermined rotation speed, the solenoid valve 31 is opened and the air tank is opened. Compressed air is supplied from 30 to the actuator 20. Then, the diaphragm is pushed and the waste gate valve 21 is pressed.
Is opened and exhaust gas is supplied to the power turbine 22. That is, when the number of revolutions exceeds a predetermined value, surplus exhaust gas is supplied to the power turbine 22, and the power turbine 22 recovers the energy of the exhaust gas. Therefore, according to this embodiment as well, it is possible to obtain the same effects as the first embodiment.

[0019]

As described above, according to the present invention, the waste gate valve is opened when the intake pressure exceeds the predetermined pressure or when the engine speed exceeds the predetermined speed. Exhaust gas is supplied to the power turbine through the gate valve, which drives the power turbine that is being transmitted to the output shaft of the engine. Therefore, the engine can collect the surplus exhaust gas in the high speed / high load region by the power turbine, and the fuel efficiency of the engine in the high speed region can be improved.

[Brief description of drawings]

FIG. 1 is a piping diagram showing a turbocharged engine of a first embodiment.

FIG. 2 is a graph showing a net fuel consumption rate with respect to an engine speed.

FIG. 3 is a piping diagram of a turbocharged engine of a second embodiment.

[Explanation of symbols]

 10 engine body 11 turbocharger 12 exhaust turbine 13 compressor 14 rotating shaft 15 air cleaner 16 intercooler 20 actuator 21 wastegate valve 22 power turbine 23 output shaft 24, 25 gear 26 fluid coupling 30 air tank 31 solenoid valve 32 ECU 33 rotation detection sensor

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display area F02B 41/10 A

Claims (1)

[Claims] 1. A turbocharged engine in which an exhaust turbine of a turbocharger is driven by exhaust gas of an engine and intake air is compressed by a compressor of the turbocharger, when an intake pressure exceeds a predetermined pressure or When the number of rotations of the turbocharger exceeds a predetermined number of rotations, the wastegate valve is provided on the upstream side of the exhaust turbine of the turbocharger so as to open and release the exhaust gas; A turbocharged engine including: a power turbine driven by exhaust gas supplied through a gate valve;