JPH04164123A - Two-step supercharger of engine for vehicle - Google Patents

Abstract

PURPOSE:To prevent interference caused by confluence of exhaust gas by allowing exhaust gas flows discharged to both exhaust systems to make a confluent flow in series to both exhaust turbines at the time of a low speed and a low load and on the other hand, by allowing them to flow in parallel and individually at the time of a high speed and a high load. CONSTITUTION:Exhaust systems 15, 17 for discharging exhaust gas supplied from a plurality of cylinders of an engine while dividing the same exhaust gas into two system lines, and two turbochargers 9, 7 in which turbine units 33, 41 are positioned individually in the exhaust systems 15, 17, are provided. Communicating passages 31, 23 and control valves 45, 47, 37, 39 are provided in both exhaust systems 15, 17. Opening/closing operations of the control valves 45, 47, 37, 39 are controlled by a control circuit 49 so as to make exhaust gas discharged to both exhaust 15, 17 to be confluent in series to both turbine units 33, 41 at the time of a low speed and a low load and on the other hand, to flow individually in parallel at the time of high speed and a high load. It is thus possible to prevent fault in which function reduction of the turbo chargers 9, 7 may take place by interference following confluence of exhaust gas at the time of high speed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a two-stage supercharging device for an automobile engine equipped with a two-speed exhaust turbine, and in particular, to a two-stage supercharging device for an automobile engine equipped with a two-speed exhaust turbine. This invention relates to a two-stage supercharging device that can be used to perform supercharging.

゛ [Conventional technology] In a turbocharger that uses the energy of exhaust gas to rotate a turbine using exhaust pressure, generally speaking, turbocharging efficiency is effective at low vehicle speeds, but exhaust resistance increases at high speeds. This causes an increase in back pressure and a decrease in output. Conversely, what is effective at high speeds has the characteristic that at low speeds the supercharging efficiency decreases and the response worsens. Various efforts have been made to minimize these two contradictory characteristics. A typical example is a twin turbo, which has two turbochargers, reduces rotational inertia mass, improves response at low speeds, and obtains a large amount of supercharging at high speeds, resulting in high output.

Recently, as seen in JP-A-58-190516 and JP-A-61-291.725, the capacities of the two turbochargers are changed, and supercharging is carried out in different combinations depending on the vehicle speed. Something has also been proposed.

[Problem that the invention attempts to solve]

However, in the above-mentioned prior art, since the engine has a single exhaust system, interference occurs when exhaust gases from multiple cylinders are combined, resulting in a decrease in the function of the turbocharger.

Furthermore, at high speeds, it is desirable to divide the exhaust gas flow into two paths and connect them in parallel so that each path drives their own exhaust turbines. There also arises a problem that more fluid tends to flow to the easier turbine side, resulting in uneven operation between the two turbochargers.

The present invention was proposed with the intention of solving the above-mentioned problems.
The purpose of the present invention is to provide a two-stage supercharging device that allows two turbochargers to function evenly.

[Means to solve the problem]

In order to achieve the above object, a two-stage supercharging device according to the present invention includes a first and second exhaust system that separates and discharges exhaust gas from a plurality of cylinders of an engine into two systems; two turbochargers, a first and a second turbocharger each having an exhaust turbine located in each of the exhaust systems, and exhaust gas provided in the first and second exhaust systems to be discharged to both exhaust systems; The distribution system is configured according to the vehicle speed so that the flow merges and flows in series to the first and second exhaust turbines at low speeds and low loads, and flows separately to the first and second exhaust turbines in parallel at high speeds and high loads. The invention is characterized by comprising a communication path and a control valve for switching.

[For production]

Based on the above configuration, the present invention provides a low exhaust pressure at low speeds and low loads because the two exhaust turbines are driven one after another by the entire amount of exhaust gas discharged from the first and second exhaust systems. Even at low speeds, a predetermined supercharging effect can be obtained and the responsiveness can be improved.

Also, at high speeds and high loads, the exhaust gas discharged from the first and second exhaust systems flows in parallel to two exhaust turbines for each system, driving each turbine separately, reducing back pressure. , the effect of improving output by reducing exhaust resistance at high speeds and high loads can be obtained.

At high speeds and high loads, the exhaust gases from multiple cylinders do not merge into one, but are divided into two lines and distributed separately. This prevents the inconvenience of deterioration of turbocharger function, and since the exhaust gas is divided into two streams from the beginning and flows, there is no inconvenience that the exhaust gas flows only toward the side where it is easier to flow to the two turbines. Effects such as being able to eliminate the inconvenience caused by uneven operation of the two turbochargers can be obtained.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

FIG. 1 shows an overall schematic view of a two-stage supercharging device according to the present invention, and the illustrated one shows an example applied to a horizontally opposed six-cylinder engine. 'In the engine body l,
An intake passage 3 having an air cleaner 2 at its end is connected to the intake system, and two first and second turbochargers (hereinafter simply referred to as turbos) 6.7 are installed in the middle of this intake passage 3. are provided, and one blower section 61, 71 constituting each turbo is disposed within the intake passage 3.

Further, the exhaust system of the engine main body l has a first exhaust system 4 and a first exhaust system 4, so that the exhaust gas discharged from the horizontally opposing left and right cylinder groups is divided into two series of exhaust passages 41, 51 and distributed. The turbine section 62 on the first turbo 6 side is located in the middle of the first exhaust passage 41, and the second turbo 7 is located in the middle of the second exhaust passage 51.
A side turbine section 72 is arranged.

In the first and second exhaust systems 4 and 5, both exhaust passages 41 and 51 are communicated with each other by a first communication passage 8 on the upstream side of the position where the turbine section 62 of the first turbo 6 is disposed. Also, on the downstream side of the position where the turbine section 62 is disposed, both the exhaust passages 41 and 51 are communicated with each other by the second communication passage 9.

A first control valve 11 and a second control valve 12 are interposed in the first communication passage 8 and the second communication passage 9, respectively, for controlling opening and closing of the passages. Furthermore, the first exhaust passage 41
Also, a third control valve 13 for controlling the opening and closing of the first exhaust passage 4 is provided downstream of the position where the second communication passage 9 is branched, and a third control valve 13 for controlling the opening and closing of the first exhaust passage 4 is also provided in the second exhaust passage 5I. ．． A second exhaust passage 5 is located downstream of the position where the communication passage 8 is connected.
A fourth control valve 14 that controls opening and closing of the fourth control valve 1 is provided.

These first to fourth control valves 11, 12, 13, 14 have respective control units 11a, 12a, 13a.
, L4a are connected to the control circuit 20 and controlled. This control is carried out using a map graph representing the rotational speed and torque, or the rotational speed and horsepower, as shown in FIGS. 2 and 3, for example.
At low speed and low load, the first control valve 11 and the second control valve
The control valve [2] opens, and the third control valve 13 and the fourth control valve 14 open.
At high speed and high load, the first control valve 1 and the second control valve 12 are closed, and the third control valve 1 is closed.
3 and the fourth control valve 14 are controlled to open.

Note that the first exhaust passage 41 is provided with a bypass at a location where the turbine section 62 of the first turbo 6 is disposed, and a waste gate valve (WG) 15 is provided in this bypass, and the second exhaust passage 51 is also provided with a waste gate valve (WG) 15. A bypass is provided at a location where the turbine section 72 of the second turbo 7 is disposed, and a waste gate valve (WG) 1B is provided in this bypass. These waste gate valves 15 and 16 allow the turbine section 62.7
2 exceeds a predetermined upper limit, the supercharging pressure is kept constant by bypassing the exhaust gas, and the ends of the first exhaust passage 41 and the second exhaust passage 51 are connected to the muffler 42. It has an open end via 52.

Next, the operation of this embodiment will be explained.

At low speed and low load, the first control valves 11 . The second control valve 12 opens, and the other third control valve 3 and fourth control valve 14 close.

As a result, the exhaust gas discharged from the engine body ① to the first exhaust system 4 is directly transferred to the first exhaust passage 41, and also to the second exhaust system 4.
Exhaust gas discharged into the exhaust system 5 passes through the first communication passage 8 and merges into the first exhaust passage 41 side, and the total amount of the combined exhaust gas flows into the first exhaust gas as shown by the dotted chain line in FIG. After flowing through the exhaust passage 41 to rotate the turbine section 62 of the first turbo 6, the air flows further through the second communication passage 9 to the second exhaust passage 5■, and rotates the turbine section 72 of the second turbo 7. After that, it is discharged to the outside from the end of the second exhaust passage 51.

In addition, when the operating range is at high speed and high load, the output signal from the control circuit 20 causes the third and fourth control valves 13.1 to
4 is opened, and the first and second control valves 11.12 are switched to close. As a result, the exhaust gas flowing out from the engine body l to the first exhaust system 4 and the second exhaust system 5 is directed to the first exhaust passage 41 and the second exhaust system 5, respectively, as shown by the two-dot chain lines in FIG.
．． The first exhaust passage 4 flows in parallel with the second exhaust passage 51.
The exhaust gas flowing through the second exhaust passage 5 rotates the turbine section 62 of the first turbo 6, and the exhaust gas flowing through the second exhaust passage 5 rotates the turbine section 72 of the second turbo 7, so that the respective exhaust gases are rotated. is discharged separately from each end of the first exhaust passage 41 and the second exhaust passage 5.

Due to this type of distribution, in the operating range at low speeds and low loads, the total amount of exhaust gas emitted from the six cylinders is reduced to two turbo 6.7
turbine section 82.72 of both turbine sections 82.72.
By rotationally driving the exhaust turbines 62 and 72, the exhaust turbines 62 and 72 can be sufficiently driven even at low speeds with low exhaust pressure.
and improve its responsiveness.

In addition, at high speed and high load, the exhaust gas emitted from half of the six cylinders is divided and separately distributed in parallel to the turbine sections 62.72 of the first and second turbos 6.7,
At this time, since the exhaust pressure is high, each turbine section 62.7
Even though the engine 2 is rotated as required, the output is improved by reducing the exhaust resistance, that is, the back pressure.

Moreover, since the two turbo turbine sections 82 and 72 are always being driven, there is no drop in boost pressure when switching control, that is, a step, which is common in conventional sequential turbos.
Better supercharging performance can be obtained in all operating ranges.

Furthermore, at high speeds and high loads, the exhaust turbine control exhaust system is divided into two systems instead of one system as in conventional prior art, so there is no interference caused by the merging of exhaust gases at high speeds, and the turbocharger is Deterioration of functionality is suppressed. In addition, at high speeds, the exhaust gas flowing through one exhaust system always turns one turbine, and there is no tendency for the exhaust gas to flow toward the exhaust turbine with less resistance, as in the conventional prior art. There is no unevenness in the operation of the base turbocharger.

Also, at low speeds and low loads, the exhaust gas flows from the first exhaust passage 41 through the second exhaust passage 51 to one of the mufflers 52, which causes muffled noise and makes it easier to obtain low-speed torque. In addition, high output can be obtained by switching to an outflow path that passes through both mufflers 42 and 52.

〔Effect of the invention〕

As explained above, according to the two-stage supercharging device according to the present invention, at low speed and low load, the two exhaust turbines are driven by the entire amount of exhaust gas discharged from the first and second exhaust systems. Therefore, at low speeds with low exhaust pressure, a sufficient supercharging effect can be obtained and the response can be improved, and at high speeds and high loads, the exhaust gas discharged from the first and second exhaust systems is Furthermore, since the exhaust gas is configured to flow through two exhaust turbines in parallel and drive each turbine separately, back pressure is reduced, exhaust resistance is reduced, and high output can be ensured.

Furthermore, at high speeds and high loads, the exhaust gases from multiple cylinders do not merge into one system, but are divided into two lines and circulated separately. This prevents the inconvenience of turbocharger performance deterioration due to interference, and since the exhaust gas is divided into two streams from the beginning, the inconvenience of flowing only to the side that is easier to flow to the two exhaust turbines is avoided. This also has the advantage of eliminating the inconvenience of uneven operation of the two turbochargers.

[Brief explanation of drawings]

FIG. 1 is an overall schematic explanatory diagram of a two-stage supercharging device according to an embodiment of the present invention, and FIGS. 2 and 3 are diagrams showing an example of a control map for controlling with the control circuit of FIG. 1. be. ■...Engine body, 2...Air cleaner, 3...
・Intake passage, 4... First exhaust system, 41... First exhaust passage, 42.
...Muffler of first exhaust passage, 5...Second exhaust system, 5I...Second exhaust passage, 52.
...Muffler 6 of the second exhaust passage...First turbocharger, 61...The same blower part, 62...The same exhaust turbine part, 7...The second turbocharger, 71...The same Blower part, 72... Exhaust turbine part, 8... First communication path, 9... Second communication path, 11,
12.13.14...First to fourth control valves, 15, 1
6...Wastegate valve (WG), 20...Control circuit, a...Control line Patent applicant Fuji Heavy Industries Co., Ltd. agent Patent attorney Nobu Kobashi Slag quantity Patent attorney Wataru Kokura

Claims (1)

[Scope of Claims] First and second exhaust systems that separate and discharge exhaust gas from a plurality of cylinders into two systems; and a second exhaust system in which exhaust turbines are respectively located in the first and second exhaust systems. It is provided with two turbochargers, 1 and 2, and the above-mentioned first and second exhaust systems, and the exhaust gas discharged to both exhaust systems is combined at low speed and low load to be combined into the first and second exhaust systems. The exhaust system is equipped with a communication passage and a control valve that switch the flow path according to the vehicle speed so that the exhaust gas flows in series with the turbine, and in parallel with each of the first and second exhaust turbines at high speed and high load. Features of a two-stage supercharging device for automobile engines.