JPH03151519A - Multiple cylinder engine with turbo charger - Google Patents

Abstract

PURPOSE:To improve supercharging efficiency at the low speed time and motive pressure supercharging effect at the low-middle time in a two-stage twin turbo engine by independently arranging a plurality of exhaust passages to a turbine inlet of a turbocharger so as to prevent mutual exhaust interference. CONSTITUTION:At the low speed and transient time of an engine, an exhaust changeover valve 49 is closed. Exhaust air from first to third cylinders #1-#3 is supplied to a turbine 45 of a first turbocharger 41 via a collection part 39 of exhaust passages 37, an exhaust passage 43 and an inlet 45a. Exhaust air from fourth or sixth cylinders #4-#6 is also supplied to the same turbine 45. Only the first turbocharger 41 is actuated by the exhaust air from all cylinders so as to increase supercharging pressure at the low speed. Exhaust passages 43, 48 are independently formed to the inlets 45a, 45b of a turbine scroll respec tively so as to prevent mutual exhaust interference.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention arranges two turbochargers in parallel, supercharging with only one turbocharger in the low speed range, and supercharging with both turbochargers in the high speed range. The present invention relates to a turbocharged multi-cylinder engine, a so-called two-stage twin-turbo engine.

[Prior Art] In a turbocharged multi-cylinder engine, for example, as shown in FIG. 10 (the illustrated example is a six-cylinder engine),
Cylinders #1, #2, #3 and # that do not cause exhaust interference with each other
Exhaust passages from two cylinder groups: 4, #5, #6 1.2.
3 and 4.5.6 independently and connected to the turbine 9.10 of the turbocharger 7.8, dynamic pressure supercharging (pulse charging) that effectively utilizes the dynamic pressure of the exhaust gas can be realized. In other words, in the supercharging turbo system shown in Fig. 10, the exhaust pressure fluctuations are as shown in Fig. 11, and since no exhaust interference occurs, the exhaust pressure retention is 1.
The pressure in the valley of No. 1 is sufficiently low. The engine intake cam and exhaust cam intake valve, exhaust valve riff 1~operation area is the 1st
As shown in region 12.13 of FIG. 2, they overlap each other, and gas exchange in the combustion chamber takes place in the overlap region. As shown in FIG. 10, this overlapping region substantially coincides with the valley of the exhaust pressure characteristic 11. therefore,
At low speeds when the wastegate valve (path shown) is closed, the intake pressure overcomes the sufficiently low exhaust pressure and the intake air flows into the combustion chamber, allowing smooth gas exchange and increasing volumetric efficiency. Torque is improved.

However, in the above system, exhaust gas is supplied to the two turbochargers 7.8 even in the low speed range where the gas flow rate is low, so each turbocharger 7.
．． 80 The problem is that the number of revolutions does not increase sufficiently and the supercharging pressure does not increase sufficiently, resulting in an insufficient degree of torque improvement.

To solve this problem, for example, as shown in FIG. 13, an exhaust switching valve 22 is provided downstream of one of the turbines of the two turbochargers 20 and 21, and the exhaust switching valve 22 is closed in the low speed range, so that the exhaust gas from the two cylinders is closed. One turbocharged T20
A so-called two-stage twin turbo system is known in which the turbocharger X720 is supplied to the
0-1224, Utility Model Application Publication No. 178329/1983).

[Problems to be Solved by the Invention] However, in the above-mentioned two-stage twin turbo system, since the exhaust gas from all cylinders is collected in one port 1~, interference occurs between the exhaust gases from each cylinder, and this exhaust interference Therefore, there is a problem in that the dynamic pressure of the exhaust cannot be used effectively, especially in low and medium speed ranges where the exhaust flow rate is small.

Further, since the exhaust gas from each cylinder is collected in one bow 1~, the exhaust pressure becomes high, and as shown in FIG. 14, the exhaust pressure characteristic becomes a characteristic 23 that fluctuates in a relatively high range.

As a result, the exhaust pressure increases when the intake cam and exhaust cam overlap, reducing gas exchange efficiency in the combustion chamber.
This makes it difficult to improve volumetric efficiency and torque.

The present invention takes advantage of the two-stage twin turbo system's improved supercharging efficiency in the low speed range, while suppressing exhaust interference and effectively utilizing the dynamic pressure of the exhaust to increase the dynamic pressure supercharging effect in the low and medium speed range. The purpose is to increase engine output performance by keeping exhaust pressure low during intake and exhaust cam overlap to ensure smooth gas exchange.

[Means for Solving the Problems] A multi-cylinder engine with a turbocharger of the present invention that meets this objective has a first and a second turbocharger arranged in parallel, and in a low speed range, the turbocharger is placed downstream of the turbine of the second turbocharger. In a multi-cylinder engine with a turbocharger, the exhaust switching valve installed is closed and supercharging is carried out only by the first turbocharger, and in the high-speed range, the exhaust switching valve is opened and supercharging is carried out by both the first and second turbochargers. Exhaust passages from cylinders that do not cause exhaust interference are assembled independently into first and second exhaust passage groups, and the first exhaust passage group is connected to the turbine of the first turbocharger, and the second exhaust passage group is connected to the turbine of the first turbocharger. is connected to the turbine of the second turbocharger, and the first exhaust passage group is connected to the second turbocharger P, the second exhaust passage group is connected to the first turbocharger, and the other exhaust passage group is connected to the other exhaust passage group. consists of independently connected units at least up to just before the turbine inlet.

[Function] In such a turbocharged engine, the exhaust switching valve is closed in the low speed range, and the exhaust from the second cylinder, that is, through both the first and second exhaust passage groups, is transferred to the first turbocharger. The fuel is sent to the turbine, and only the first turbocharger is operated to increase supercharging pressure in the low speed range.

Furthermore, the exhaust passages from each cylinder that do not cause exhaust interference with each other are grouped together as a first and second exhaust passage group, and both exhaust passage groups are composed of at least the first, second, and second exhaust passage groups.
Since the second turbocharger is formed independently without communicating with the second turbocharger up to just before the turbine inlet, pressure interference between the two exhaust passage groups is substantially avoided. Therefore, exhaust interference is avoided, and the dynamic pressure of the exhaust gas from each exhaust passage is effectively used by the turbine of each turbocharger P, and the dynamic pressure supercharging effect is particularly enhanced in the low and medium speed ranges.

Furthermore, the exhaust passages from all the cylinders are collected into two exhaust passage groups, and these two exhaust passage groups are connected to both the first and second turbochargers, so that the exhaust gas from each cylinder is The exhaust pressure at the time of exhaust, that is, gas exchange, can be kept low, gas exchange with intake air is performed smoothly, and the volumetric efficiency of intake air is improved.

[Embodiments] Preferred embodiments of the present invention will be described below with reference to the drawings.

1 to 6 show a turbocharged multi-cylinder engine according to an embodiment of the present invention, and show a case where the present invention is applied to a six-cylinder engine. 7 and 8 show the operating states of the engine, and FIG. 9 shows the exhaust pressure characteristics.

In FIGS. 1 to 6, 30 indicates the engine body, and #1 to #6 indicate each cylinder. #1~#
Among the 6 cylinders, cylinders #1 to #3 that do not cause exhaust interference with each other
and exhaust passages 31.32.33 from cylinders #4 to #6
The exhaust passages 34, 35, and 36 are collected in a gathering portion 39, 40 as a first exhaust passage group 37 and a second exhaust passage group 38, which are independent from each other.

As turbochargers, two turbochargers 41 and 42, a first and a second turbocharger, are arranged in parallel. The exhaust passage 43 from the gathering part 39 of the first exhaust passage group 37 is connected to the turbine 45 of the first turbocharger 41 .

Exhaust passage 44 from the collection section 40 of the second exhaust passage group 38
is connected to the turbine 46 of the second turbocharger 42 . Another exhaust passage 47 is branched from the gathering part 39 of the first exhaust passage group 37, and this exhaust passage 47 is the one used for the second turbocharger t=42.
4 is independently connected to the inlet of the turbine 46. Another exhaust passage 48 is branched from the gathering part 40 of the second exhaust passage group 38, and the exhaust passage 48 is connected to the first turbocharger 41, and the other exhaust passage 43 is connected to the turbine 4.
5 entrances are connected independently. In this example, each turbocharger 41.42 includes a turbine 45.4.
6 turbine scrolls each have two inlets 45a.
, 45b, 146a, and 146b, the exhaust passage 43 is connected to the inlet 45a, the exhaust passage 48 is connected to the inlet 45b, the exhaust passage 44 is connected to the inlet 46a, and the exhaust passage 47 is connected to the inlet 46b. has been done.

However, although not shown, the present invention may be a single-entry turbocharger with one inlet, and the exhaust passage 43 and the exhaust passage 48, and the exhaust passage 44 and the exhaust passage 47 are connected to each turbocharger. It is sufficient that they are formed independently so that they do not communicate with each other until immediately before the turbine inlet.

Downstream of the turbine 46 of the second turbocharger 42,
An exhaust switching valve 49 is provided, which is closed during engine low speed ranges and transitions, and opened during high speed ranges. 50.51
is the compressor of each turbocharger 41.42.

In this embodiment, as shown in FIGS. 2 and 3, the winding directions of the turbine scrolls of the turbines 45, 46 of the turbocharger 41, 42 are set to be opposite,
As shown in FIG. 4, each turbocharger 41, 42 is assembled as a turbocharger unit 52 with turbine flanges facing each other. In addition, FIGS. 5 and 6 show the exhaust manifold 53 of this embodiment.
As shown, the exhaust passages 47, 48 and the exhaust outlet 54
．． 55 or vertically shifted.

The operation of the embodiment device configured as described above will be explained.

At low speeds and during transient periods, the exhaust gas switching valve 49 is closed, as shown in FIG. As shown by the arrow in the figure, #1,
Exhaust from #2 and #3 cylinders goes through exhaust passage 31.32.3
3 to 1st exhaust passage? ! The first turbocharger 4 passes through the collecting part 39, the exhaust passage 43, and the inlet 45a.
Exhaust gas from cylinders #4, #5, and #6 is also sent to the turbine 45 of No. 1, through the exhaust passage 34, 35, 36, the gathering part 40 of the second exhaust passage group 38, the exhaust passage 48, and the inlet lower 15b. It is sent to the turbine 45. Since only one turbocharger V741 is operated by the exhaust gas from all cylinders, a sufficient displacement is secured for driving the turbochargers 1-41 even in a low speed range, and a sufficiently high supercharging pressure is obtained.

In the high speed range, the exhaust volume is large, so the exhaust switching valve 49
is opened, and the exhaust gas flows through both the first and second turbochargers 41.
．． 42 to operate both turbochargers.

More specifically, the exhaust gas from the first exhaust passage group 37 is sent from the gathering part 39 via the exhaust passage 43 and the exhaust passage 47 to the turbine 45.46 of the turbocharger 41.42, and is then sent to the turbine 45.46 of the turbocharger 41.42. The exhaust gas from 38 is sent from the collection part 40 to the turbocharger t via an exhaust passage 44 and an exhaust passage 48.
741.42 to turbine 45.46.

In this system, when only the first turbocharger 41 is operated, the exhaust passage 43
, the exhaust passage 48 is the inlet 45a of the turbine scroll,
Since up to 45b are formed independently, exhaust pressure interference between the exhaust passages can be avoided, and even when both the first and second turbochargers 41 and 42 are operated, the exhaust passages 43 and 48 and exhaust passage 44, exhaust passage 47
are the inlets 45a and 45 of the turbine scroll, respectively.
b and the inlets 46a and 46b are formed independently, so that the exhaust passages 43, 48 and 44.
47 exhaust pressure interferences are avoided. Therefore, exhaust interference is prevented, and the dynamic pressure of the exhaust gas is effectively used for driving each turbine. In particular, in the low and medium speed range, the displacement is smaller than in the high speed range, and the dynamic pressure of the exhaust is correspondingly small, but this dynamic pressure is effectively used without being diminished by exhaust interference, so dynamic pressure overload is reduced. The charging effect is enhanced and sufficient supercharging pressure can be obtained from the turbocharger.

Also, the turbocharger 41 or the turbocharger 4
1 and the turbocharger 42 are formed independently up to the turbine inlet or just before the inlet. As a result, as shown in FIG. 9, the exhaust pressure characteristics (broken line) ) 61, the exhaust pressure characteristic (solid line) 62 has a lower pressure in the valley during pressure fluctuation? Therefore, the exhaust pressure in the overlap region 63 of the intake and exhaust cams can be reduced. Therefore, gas exchange between intake and exhaust gases is performed smoothly, and the volumetric efficiency of intake air is improved.

In addition, one turbocharger 4 with the exhaust switching valve 49 closed
1. During supercharging, dynamic pressure of the exhaust is also applied to the turbine 46 of the second turbocharger 42 located upstream of the exhaust switching valve 49, and the dynamic pressure causes the second turbocharger 42 to perform a run-up rotation. However, since the dynamic pressures from both the first and second exhaust passage groups 37, 38 are applied to each other without exhaust interference, the run-up rotation speed is increased.

As a result, the shock at the time of switching from one turbocharger operation to two turbocharger operation is reduced.

Roughly speaking, as in this embodiment, the exhaust manifold 53
By vertically shifting the exhaust outlet 54.55 of the turbocharger 41.42 and reversing the winding direction of the turbine scroll of the turbocharger 41.42, the exhaust flow becomes smooth, and the turbine 45.46 of the turbocharger 41.42
The flanges can be mounted facing each other, allowing for a compact design and a well-balanced configuration in terms of appearance.

Although the above embodiment has been described for the case of a 6-cylinder engine, other multi-cylinder engines, for example, 4-cylinder engines, can also be used to extend the exhaust gas from a group of cylinders that do not cause exhaust interference to each other up to the turbine inlet of the turbocharger or just before the inlet. The invention can be applied by forming the passages independently.

[Effects of the Invention] As explained above, in the multi-cylinder engine with a turbo dissage V according to the present invention, the exhaust passage is formed independently up to the turbine inlet of the turbocharger or just before the inlet, thereby avoiding exhaust interference. While taking advantage of the stage twin turbo system's improved supercharging efficiency in the low speed range, it is also possible to effectively utilize the dynamic pressure of the exhaust, making it possible to improve output torque, especially in the low and medium speed ranges.

In addition, the exhaust pressure during intake and exhaust gas exchange in the combustion chamber can be kept low, allowing smooth gas exchange, increasing the volumetric efficiency of intake air, and improving output torque.

In general, by effectively using the dynamic pressure of the exhaust, it is possible to increase the run-up speed of the other turbocharger when one turbocharger is operating, reducing the shock when switching from one turbocharger to two turbochargers. You can also.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective bottom view of a multi-cylinder engine with turbocharged Az according to an embodiment of the present invention, and FIG.
3 is a vertical sectional view taken along the line 2--2 in FIG. 1, FIG. 4 is an enlarged front view of the turbocharger section of the device in FIG. 1 is a plan view of the exhaust manifold of the device shown in FIG. 1, FIG. 6 is a front view of the exhaust manifold of FIG. , Fig. 8 is a schematic perspective bottom view showing the flow of exhaust gas when the exhaust switching valve of the device shown in Fig. 1 is open, Fig. 9 is a diagram showing the relationship between exhaust pressure and crank angle of the device shown in Fig. 1, and Fig. 10 is a schematic perspective bottom view of a conventional twin-turbo engine, Figure 11 is a diagram showing the relationship between the exhaust pressure and crank angle of the device in Figure 10, and Figure 12 shows the overlap area of the intake and exhaust cams of the engine in Figure 10. 13 is a schematic transparent bottom view of a conventional two-stage twin turbo engine; FIG. 14 is a diagram showing the relationship between exhaust pressure and crank angle of the engine shown in FIG. 13. 30...Engine body 31.32.33.34.35.36...Exhaust passage 37...First exhaust passage group 38...Second Exhaust passage groups 39, 40, gathering portion 41, first turbocharger 42, etc.
・Second turbocharger 43.44.47.48・
...Exhaust passage 45.46...Turbine 45a, 45b 146a, 46b...
--Population 49... Exhaust switching valve 50151... Compressor 53... Exhaust manifold 54.55.
...Exhaust outlet Fig. 2 Fig. 3 Fig. 4 Fig. 12 Fig. 13 Crank angle Cυ

Claims (1)

[Claims] 1, the first turbocharger, and the second turbocharger are arranged in parallel, and in the low speed range, the exhaust switching valve installed downstream of the turbine of the second turbocharger is closed, and supercharging is performed only by the first turbocharger, and in the high speed range, the exhaust switching valve is closed. In a turbocharged multi-cylinder engine in which exhaust switching valves are opened and supercharging is performed by both first and second turbochargers, exhaust passages from cylinders that do not cause exhaust interference with each other are defined as first and second exhaust passage groups. The first exhaust passage group is connected to the turbine of the first turbocharger, the second exhaust passage group is connected to the turbine of the second turbocharger, and the first exhaust passage group is connected to the second exhaust passage group. of the turbocharger, the second exhaust passage group is connected to the first exhaust passage group.
A multi-cylinder engine with a turbocharger, each of which is independently connected to the other exhaust passage group at least up to just before the turbine inlet.