JP2539655B2 - Twin turbo type internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a twin turbo internal combustion engine in which a plurality of cylinders are divided into two groups and each cylinder group is provided with an exhaust turbocharger.

(Prior Art and Problems Thereof) In this type of twin turbo internal combustion engine, a prior art in which two exhaust passages are communicated with each other by a connecting pipe is known from Japanese Utility Model Publication No. 60-178329. There is.

However, in this prior art, the pulsating pulses of the exhaust gas flowing through the two exhaust passages interfere with each other, and the pulsating pulses decrease, and there is room for improvement in terms of supercharging efficiency. Further, especially at low speeds, the amount of exhaust gas is small and the supercharging efficiency is significantly reduced.

A technique for dividing a plurality of cylinders into two groups and flowing exhaust gas to an exhaust turbocharger is disclosed in Japanese Examined Patent Publication Nos. 38-1154 and 59-692.

(Object of the Invention) First, the present invention relates to a twin turbo internal combustion engine,
It is an object of the present invention to provide a twin turbo internal combustion engine that can prevent a decrease in supercharging efficiency due to exhaust interference and can improve the performance in the medium to low speed range with a low pressure stage exhaust turbocharger.

(Structure of the Invention) (1) Technical Means The present invention divides a plurality of cylinders into two groups, and in a twin turbo internal combustion engine provided with an exhaust turbocharger in each cylinder group, high pressure is applied to each cylinder group. A staged exhaust turbocharger is provided, and a connecting pipe that connects both exhaust passages is provided between two exhaust passages that connect each high pressure stage exhaust turbocharger and each cylinder group,
A twin scroll turbine is provided in one of the exhaust turbochargers, and a partition wall that divides a cross-sectional area of the first exhaust passage into two is formed downstream of the communication pipe of the first exhaust passage that is connected to the twin scroll turbine. (1) A first switching valve is provided at a connecting portion between the exhaust passage and the communication pipe to close the communication pipe opening when the valve is closed, and to switch the communication pipe to communicate with one of the divided passages of the first exhaust passage when the valve is opened, and the other. In the connection between the second exhaust passage and the connecting pipe connected to the turbocharger, the connecting pipe opening is closed when the valve is closed, and when the valve is opened, the entire amount of exhaust gas in the second exhaust passage is switched to the connecting pipe. Two switching valves are installed,
One low-pressure exhaust turbocharger having a twin scroll turbine is provided downstream of both the high-pressure exhaust turbochargers, and the high-pressure exhaust is supplied to each swirl chamber of the twin scroll turbine of the low-pressure exhaust turbocharger. An exhaust connection pipe was installed to guide the exhaust gas from the turbocharger independently, and a supply connection pipe was installed to guide the supercharged air from the low-pressure exhaust turbocharger to both high-pressure exhaust turbochargers. It is a twin-turbo type internal combustion engine characterized by the above.

(2) Action When both switching valves are opened, exhaust gas is allowed to flow to the twin scroll turbine of the high pressure exhaust turbocharger while preventing exhaust interference with the partition wall and twin scroll turbine, and supercharging is performed with high efficiency.

At the same time, the exhaust gas is made to flow from one of the exhaust connecting pipes to the twin scroll turbine of the low pressure exhaust turbocharger and is further supercharged.

When both switching valves are closed, the exhaust pipe and the connecting pipe are shut off to eliminate the influence of the connecting pipe, improve the supercharging efficiency of the high-pressure exhaust turbocharger, and connect the low-pressure exhaust turbocharger from the exhaust connecting pipe. The exhaust gas is made to flow independently to the turbocharger to improve the supercharging efficiency of the low pressure exhaust turbocharger.

(Embodiment) In FIG. 1 showing a twin turbo diesel engine adopting the present invention, 10 is an engine body. This engine body 10 is 6
It has a cylinder 11 of cylinders, and the exhaust manifolds 12 of the cylinder 11 are assembled for every three cylinders and are connected to the first exhaust passage 13 and the second exhaust passage 14.

The first exhaust passage 13 is connected to a high pressure exhaust turbocharger 15, and the high pressure exhaust turbocharger 15 has two scroll chambers in a twin scroll turbine 16. Second exhaust passage 14
Is connected to a high pressure exhaust turbocharger 17, and the high pressure exhaust turbocharger 17 has a single scroll chamber in a single scroll turbine 18. The blowers 19 and 20 of the high-pressure stage turbochargers 15 and 17 are connected to the air supply manifold 23 of the engine body 10 by air supply pipes 21 and 22, and the air supply manifold 23 is provided with an intercooler 24. A check valve 25 is provided in the air supply pipe 21. In the figure, 27 is an intercooler.

Further, only one low-pressure stage exhaust turbocharger 26, which will be described in detail later, is provided on the downstream side of both high-pressure stage exhaust turbochargers 15, 17.

A connecting pipe is provided between the first exhaust passage 13 and the second exhaust passage 14.
A connection pipe 30 connects the first exhaust passage 13 and the second exhaust passage 14 with each other. A first switching valve 31 is provided at a connecting portion between both ends of the communication pipe 30 and the first exhaust passage 13 and the second exhaust passage 14.
A second switching valve 32 is provided, and the first switching valve 31 and the second switching valve 32 serve to control the opening and closing of the connecting pipe 30 as described later in detail. Expansion joint in the center of the connecting pipe 30
33 are provided.

A partition wall 34 is provided downstream of the communication pipe 30 in the first exhaust passage 13.
Is formed, and the partition wall 34 divides the first exhaust passage 13 so as to divide the sectional area of the first exhaust passage 13 into two substantially equal parts. Therefore, the exhaust gas flowing through the first exhaust passage 13 independently flows into the spiral chamber of the twin scroll turbine 16 through the divided passages 35 and 36 defined by the partition wall 34.

The first switching valve 31 is pivotally supported by a fulcrum 37, and the fulcrum 37 is arranged near the upstream side of the opening of the connecting pipe 30. Also,
The fulcrum 38 of the second switching valve 32 is arranged near the downstream side of the opening of the connecting pipe 30.

The first switching valve 31 and the second switching valve 32 have a partition wall 34 at the tip end of the first switching valve 31 at the time of medium and low speed and high load shown in FIG.
The second switching valve 32 is fully opened so that the entire amount of the exhaust gas in the second exhaust passage 14 flows to the connecting pipe 30. Next, at high speed and high load, as shown in FIG. 2, both ends of the connecting pipe 30 are closed so as to close the openings.

Between the twin scroll turbine 16, the single scroll turbine 18, and the twin scroll turbine 60 of the low pressure exhaust turbocharger 26, there are twin scroll turbines.
Exhaust gas connection pipes 61 and 62 for flowing exhaust gas are connected to the respective 60 swirl chambers. Universal joint 6 at the base end of the exhaust connection pipe 61, 62
3 and 64 are installed. The tips of the exhaust connection pipes 61 and 62 are
A turbine support 65 supports the base on which the engine body 10 is mounted. Further, the tip end portions of the exhaust connection pipes 61 and 62 are connected to the twin scroll turbine 60 so that the exhaust gas from both turbines 16 and 18 is independently guided to the respective swirl chambers within the twin scroll turbine 60. There is.

The blower 70 of the low pressure exhaust turbocharger 26 has an air supply connecting pipe.
71 is connected, the air supply connection pipe 71 is an injector cooler 72
It is connected to the blowers 19 and 20 on the high voltage side via.

With the above configuration, when the amount of exhaust gas in the first exhaust passage 13 and the second exhaust passage 14 decreases and the supercharging efficiency of the high pressure exhaust turbochargers 15, 17 decreases, as shown in FIG. 1 switching valve 3
1, the second switching valve 32 is switched to guide the exhaust gas flowing through the first exhaust passage 13 to the split passage 35 by the first switching valve 31, and the exhaust gas flowing through the second exhaust passage 14 by the second switching valve 32. The connecting pipe 30 is passed through and the first switching valve 31 guides the connecting pipe 30 to the divided passage 36.

Therefore, the exhaust gas of the cylinder 11 divided into two groups is divided and supplied to the swirl chamber of the twin scroll turbine 16, and the amount of exhaust gas increases relative to the high pressure exhaust turbocharger 15. , So-called variable inlet nozzle (VG
The high pressure stage exhaust turbocharger 15 exhibits a high supercharging efficiency even with a small amount of exhaust gas by performing the same function as S).

In addition, the exhaust gas of the cylinder 11 divided into two groups is separated by the partition wall 34.
The pulsating pulses of the exhaust gas flowing through the split passages 35 and 36 do not interfere with each other and are supplied to the swirl chamber of the twin scroll turbine 16 independently of each other. Increase the salary effect.

Further, the exhaust gas supplied from the turbine 16 to the twin scroll turbine 60 of the low-pressure exhaust turbocharger 26 through the exhaust connection pipe 61 has a small cross-sectional area from the exhaust connection pipe 61 to the swirl chamber of the twin scroll turbine 60. It will flow to one side. Therefore, the amount of exhaust gas increases relative to the low pressure stage exhaust turbocharger 26, and the low pressure stage exhaust turbocharger 26 is driven with high efficiency as described above, and the supercharger from the blower 70 is used. Blower 19,2 through the air supply connection pipe 71
Flow into 0.

In the operating state of FIG. 1, the output P with respect to the rotation speed n
In Fig. 3, which is the graph of Fig. 3, the characteristic X1 is exhibited in the range of R1. This characteristic X1 is the high pressure exhaust turbocharger 15,17
As compared with the characteristic X2 and the region W2 when only the high pressure stage is operated, the output P in the medium and low speed region is improved by the region W1 by the operation only on the high pressure stage exhaust turbocharger 15 side.

At the time of high speed and high load in FIG. 2, the first switching valve 31 and the second switching valve 32 are closed so as to close both end openings of the connecting pipe 30, and the connecting pipe 30 is connected to the first exhaust passage 13 and the second exhaust passage. The exhaust gas from the first exhaust passage 13 and the second exhaust passage 14 is completely cut off from the exhaust gas 14 and directly flows to the high pressure exhaust turbochargers 15 and 17.

At high speed and high load, the exhaust gas amounts in the first exhaust passage 13 and the second exhaust passage 14 are sufficiently increased, so that the high pressure stage exhaust turbochargers 15, 17 exhibit high supercharging efficiency. Also,
Since the communication pipe 30 is shut off by the first switching valve 31 and the second switching 32, the capacity of the communication pipe 30 is the first exhaust passage 13 and the second exhaust passage.
The pulsating pulse of the exhaust gas flowing through 14 is not attenuated, and the supercharging efficiency is improved also in this aspect.

Further, a low pressure exhaust turbocharger 26 provided downstream
The exhaust gas from both turbines 16 and 18 independently flows into each of the swirl chambers through the exhaust connection pipes 61 and 62 of the twin scroll turbine 60, and the exhaust gas from both turbines 16 and 18 does not cause exhaust interference. The supercharging efficiency of the low pressure exhaust turbocharger 26 is high.

The operating condition in Fig. 2 is the range of the region W3 in Fig. 3 (rotation speed R
Perform in 2) and exhibit characteristics X3.

Next, the switching mechanism of the first switching valve 31 and the second switching valve 32 will be described with reference to FIG. In FIG. 4, a first switching valve 31 and a second switching valve
Arms 40 and 41 are formed at the base end of 32 so as to be rotatable around fulcrums 37 and 38 integrally with the first switching valve 31 and the second switching valve 32. The arms 40 and 41 project to the outside of the first exhaust passage 13 and the second exhaust passage 14.

A link 42 is rotatably connected to the tip ends of the arms 40 and 41 by pins 43 and 44, and the link 42 connects the first switching valve 31 and the second switching valve 31.
The opening / closing operation of the switching valve 32 is linked. arm
Air cylinder 45 (actuator) in the middle of 40
The rod 46 is rotatably connected, and exhibits the function of opening and closing the first switching valve 31 and the second switching valve 32 by the expansion and contraction stroke of the rod 46. The air cylinder 45 is relatively small, and only one air cylinder 45 is provided.

In the state shown in FIG. 4, the rod 46 of the air cylinder 45 is in the most shortened position. Further, the length of the arms 40 and 41 is at the most extended position by extending the stroke s from this state,
The ratio of L1: L2 is set so that the first switching valve 31 is rotated by θ1 and the second switching valve 32 is simultaneously rotated by θ2 so that the first switching valve 31 and the second switching valve 32 can be simultaneously closed. Has been set.

Note that other actuators such as a vacuum pump or a step motor can be used instead of the air cylinder 45, and length adjustment mechanisms 48 and 49 that can be fixed at arbitrary lengths are provided in the middle of the link 42 and the arm 40. It is also possible.

The compressed air from the compressed air supply mechanism 50 flows through the air cylinder 45 through the pipes 47 and 47a, and the compressed air supply mechanism 50 is controlled by the control device 51. Further, the control device 51 includes a rotation speed signal 53 from a tachometer (not shown) of the engine body 10 (FIG. 1) and a pressure gauge 54 of the first exhaust passage 13 and the second exhaust passage 14.
The pressure signal 55 from the
The operating state of the engine is determined based on 53 and 55, and at the time of medium and low speed and high load, the first switching valve 31 and the second switching valve 32 as shown in FIG.
Is opened, and the first switching valve 31 and the second switching valve 32 are closed at high speed and high load.

In the above configuration, since the first switching valve 31 and the second switching valve 32 are connected by the link 42 and the air cylinder 45 is provided, the first switching valve 31 and the second switching valve 32 at two locations are one air. It can be opened and closed with only the cylinder 45.

The first switching valve 31 and the second switching valve 32 are connected by a link 42. When the first switching valve 31 is open, the second switching valve 32 is also open and the first switching valve 31 is closed. Second switching valve when
32 also closes. Therefore, when the second switching valve 32 is open, the first switching valve 31 is not closed and the flow of the exhaust gas in the second exhaust passage 14 is not hindered, and the exhaust gas in the second exhaust passage 14 is not blocked. There is no resistance to distribution.

(Effects of the Invention) As described above, in the twin turbo internal combustion engine according to the present invention, the low pressure exhaust turbocharger 26 having the twin scroll turbine 60 on the downstream side of both the high pressure exhaust turbochargers 15 and 17 is provided. One unit is provided, and exhaust connection pipes 61, 62 for independently guiding the exhaust gas from the high pressure exhaust turbochargers 15, 17 to the respective swirl chambers of the twin scroll turbine 60 of the low pressure exhaust turbocharger 26 are provided. Since the supply air connection pipe 71 for guiding the supercharged air from the low-pressure stage exhaust turbocharger 26 to both the high-pressure stage exhaust turbochargers 15, 17 is provided, the following effects are achieved.

The kinetic energy of the exhaust gas supplied from the high pressure exhaust turbocharger 15 to the low pressure exhaust turbocharger 26 is recovered at low and medium speeds with a small amount of exhaust gas, and the blower of the low pressure exhaust turbocharger 26 is recovered. The supercharged air can be recirculated from 70 to the blower 19, and the characteristic X1 in which the output P is improved by the area W1 in the range of R1 in FIG. 3 can be exhibited.

In particular, since the exhaust gas is made to flow into the twin scroll turbine 60 only from the exhaust connection pipe 61, the supercharging efficiency of the low pressure stage exhaust turbocharger 26 can be improved even at low and medium speeds where the exhaust gas amount is small.

The exhaust gas flowing through the exhaust connecting pipes 61 and 62 interferes with the exhaust gas because the exhaust gas flows through the twin scroll turbine 60 of the low-pressure exhaust turbocharger 26 independently from the two exhaust connecting pipes 61 and 62. The supercharging efficiency is high even in the range of R2 in FIG.

[Brief description of drawings]

FIG. 1 is a structural schematic diagram of a twin turbo diesel engine adopting the present invention, FIG. 2 is a schematic diagram of a main part of FIG. 1 showing a valve closed state, FIG. 3 is a graph of rotational speed and output, and FIG. 6 is a schematic structural view showing a switching mechanism of a switching valve. 10 ... engine body, 11 ...
… Cylinder, 13 …… First exhaust passage, 15,17 …… High pressure exhaust turbocharger, 23 …… Supply manifold, 26 …… Low pressure exhaust turbocharger, 30 …… Communication pipe, 31… … First switching valve, 32 …… Second switching valve, 37,38 …… Support point, 61,62 …… Exhaust gas connection pipe, 71 …… Air supply connection pipe

Claims (1)

(57) [Claims] 1. A twin turbo internal combustion engine in which a plurality of cylinders are divided into two groups, and each cylinder group is provided with an exhaust turbocharger, and a high pressure exhaust turbocharger is provided for each cylinder group. Between the two exhaust passages that connect the high pressure exhaust turbocharger and each cylinder group, a communication pipe that connects both exhaust passages is provided.
A twin scroll turbine is provided in one of the exhaust turbochargers, and a partition wall that divides the cross-sectional area of the first exhaust passage into two is formed on the downstream side of the communication pipe of the first exhaust passage that is connected to the twin scroll turbine. (1) A first switching valve is provided at a connecting portion between the exhaust passage and the communication pipe to close the communication pipe opening when the valve is closed, and to switch the communication pipe to communicate with one of the divided passages of the first exhaust passage when the valve is opened, and the other. In the connection between the second exhaust passage and the connecting pipe connected to the turbocharger, the connecting pipe opening is closed when the valve is closed, and when the valve is opened, the entire amount of exhaust gas in the second exhaust passage is switched to the connecting pipe. Two switching valves are installed,
One low-pressure exhaust turbocharger having a twin scroll turbine is provided downstream of both the high-pressure exhaust turbochargers, and the high-pressure exhaust is supplied to each swirl chamber of the twin scroll turbine of the low-pressure exhaust turbocharger. An exhaust connection pipe was provided to independently guide the exhaust gas from the turbocharger, and a supply air connection pipe was introduced to guide the supercharged air from the low pressure exhaust turbocharger to both high pressure exhaust turbochargers. A twin-turbo internal combustion engine characterized in that