JPS60156934A - Supercharging device for engine - Google Patents

Abstract

PURPOSE:To control supercharging pressure so properly at a wide operation region, by dividing an exhaust pipe and a suction pipe of an engine into two-in-a- set ones, while installing two sets of turbosuperchargers as well as installing a valve, which opens when pressure inside the suction pipe on one side exceeds the specified value, in the exhaust pipe on the other. CONSTITUTION:An exhaust main pipe 2 of an engine E is divided into two parts, namely, each of first and second exhaust branch pipes 3 and 4, while a suction main pipe 6 is divided into each of first and second branch pipes 7 and 8, and each of turbochargers Tu1 and Tu2 is installed in each of them. Likewise, an on-off valve 9 is installed in the second exhaust branch pipe 4, and constituted so as to close in time of pressure inside the first suction branch pipe 7 being below the specified value and to open when it exceeds the specified value. With this constitution, in time of low load, the pressure inside the suction pipe is low and thereby the on-off valve 9 is closed but in time of high load, the internal pressure goes up, opening the valve 9, thus sufficient supercharging takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention utilizes exhaust energy to rotate an exhaust turbine, uses this power to drive a compressor, and thereby prepressures intake air or a mixture, using a so-called turbo supercharger. This invention relates to an engine supercharging device.

Conventionally, in the above-mentioned supercharging device, one turbo supercharger is interposed between the exhaust pipe and the intake pipe to prepress the intake air or the air-fuel mixture, so it can be used over a wide operating range of the engine. There are limits to proper boost pressure control.
There was an inconvenience that desired supercharging characteristics could not be obtained.

SUMMARY OF THE INVENTION Accordingly, the present invention provides an engine supercharging device that expands the supercharging operation range of an engine and properly controls the supercharging pressure in each supercharging operation range, thereby significantly improving supercharging characteristics. The purpose is to

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, an exhaust system Ex of an engine E includes a main exhaust pipe 2 communicating with the exhaust boat via an exhaust manifold 1, and first and second branch exhaust pipes 3 branched from the main exhaust pipe 2.
, 4, and these branch pipes 3 and 4 are respectively provided with the first branch pipes 3 and 4, which will be described later. After the second exhaust turbines T, T217 are installed, they are collected and communicated with the atmosphere via the exhaust muffler M.

The intake system In of the engine E includes a main intake pipe 6 that communicates with the intake boat via an intake manifold 5, and a first main pipe 6 that is branched from the main intake pipe 6. Second intake branch pipes 7 and 8 are provided.The branch pipes 1 and 8 are connected to the first intake branch pipes 7 and 8, respectively, which will be described later. After a second compressor (1;' + , C2k is installed), it is communicated with the atmosphere via an air cleaner 4c.

A first turbo supercharger T u I is interposed between the first exhaust branch pipe 3 and the first intake branch pipe 7 . The first turbo supercharger TWI has a conventionally known structure, and includes a first exhaust turbine T1 and a compressor C1 coupled to and driven by the first exhaust turbine T1. It is interposed in the middle of the pipe 3 and is driven by the exhaust energy of the exhaust gas flowing through the first exhaust branch pipe 3. Further, the first compressor CI is interposed in the middle of the first intake branch pipe 7, and precompresses the intake air (intake air or mixture) flowing within the first intake branch pipe 7.

Further, a second turbo supercharger Tu, 2 is interposed between the middle of the second exhaust branch pipe 4 and the middle of the second intake branch pipe 8. This second turbocharger 7'' LL2 is also of a conventionally known structure, and includes a second exhaust turbine T2 and a second compressor C7 connected and driven thereto.
The second exhaust turbine T2 is interposed in the middle of the second exhaust branch pipe 4, and is driven by the exhaust energy of the exhaust gas flowing through the second exhaust branch pipe 4. Further, the second compressor C2 is interposed in the middle of the second intake branch pipe 8, and precompresses the intake air (intake air or mixture) flowing inside the second intake branch pipe 8.

Thus, the first turbo supercharger Tal is connected to the second turbo supercharger 7.
” It is formed to have a lower capacity than W 2 .

An on-off valve 9 is interposed in the second exhaust branch pipe 4 on the upstream side of the second exhaust turbine T2, and this on-off valve 9 is arranged in the first intake branch pipe I on the downstream side of the first compressor C1. The valve is activated when the intake pressure exceeds a predetermined value.

The second exhaust branch pipe 4 includes the second exhaust turbine T2.
A wastegate 10 is connected bypassing the wastegate 10, and a wastegate valve 11 is interposed in the wastegate 10. The wastegate valve 11 is operated by the intake pressure in the second intake branch pipe 8, and the intake air is The valve is opened when the pressure exceeds a predetermined value. Furthermore, in the middle of the second intake branch pipe 8,
A check valve 12 is interposed, and this check valve 12
Prevents intake air (intake air or mixture) from flowing back into the intake branch pipe 8.

Next, to explain the operation of the embodiment of the present invention, when the engine E is currently being operated and is in a low-load operating range with a small exhaust flow rate, the on-off valve 9 is closed, so that the exhaust gas flows from the main exhaust pipe 2. A small-capacity first turbo supercharger Tu passes only through the first exhaust branch pipe 3.

After driving, the exhaust gas is discharged into the atmosphere through the exhaust muffler M. As the engine load increases, the flow rate of exhaust gas flowing from the first exhaust branch pipe 3 to the first exhaust turbine T gradually increases.
The supercharging output of the turbo supercharger Tu increases, and the engine E is operated in supercharging with the intake air pressure in the first intake branch pipe 7 having characteristics as shown by the solid line A in FIG. When the engine shifts to high-load operation and the supercharging pressure in the first intake branch pipe 7 reaches a predetermined value PB, the on-off valve 9 is opened in response to this pressure, and the exhaust from the main exhaust pipe 2 is The flow is also diverted to the second exhaust branch pipe 4, and the large-capacity second turbo supercharger T2 also begins to be driven. When the exhaust flow rate to the second exhaust branch pipe 4 increases and reaches the set value, the supercharging pressure in the second intake branch pipe 8 by the second turbo supercharger T2 is indicated by the two-dot chain line H in FIG. boost the pressure.

The compressed intake air in the second intake branch pipe 8 joins with the compressed air in the first intake branch pipe 7, passes through the main intake pipe 6 and the intake manifold 5, and is introduced into the combustion chamber of the engine E.

When the internal pressure of the second exhaust branch pipe 4 exceeds a set value, the waste gauge valve 11 is opened, and a part of the exhaust gas flowing through the valve 11 bypasses the second exhaust turbine T2 and is directly discharged to the atmosphere. Maintain the intake branch pipe 8 at the maximum boost pressure pn.

And the first. 2nd turbo supercharger T tbr ・T1L
2, the engine E is operated with a supercharging pressure characteristic as shown by the dotted line C in FIG. 2. still,
Said 1st. Second turbo supercharger TTLt.

TtL2 having the same characteristics or different characteristics may be used as necessary.

As described above, according to the present invention, when the exhaust flow rate is small and the engine is in a low load operating range, only the first turbo supercharger operates to obtain the desired supercharging characteristics, and when the exhaust flow rate is high. In the high load operating range of the engine, it is the first. Since the second turbo supercharger can work together to obtain the desired supercharging characteristics, the required boost pressure control in each operating range can be easily and accurately controlled, and the overall engine wide range can be controlled. Desired supercharging characteristics can be obtained over the operating range, and the output performance of the turbocharged engine can be significantly improved.

[Brief explanation of the drawing]

The drawings show an embodiment of the device of the present invention, and FIG. 1 is an overall system diagram thereof, and FIG. 2 is a characteristic graph thereof. E... Engine, Ex... Exhaust system, In... Intake system, T W I , +7' W 2... 1st *M
2 turbo supercharger, 2...main exhaust pipe, 3, 4...1st
．． 2nd exhaust branch pipe, 6... main intake pipe, 7. Death... 1st
．． Second intake branch pipe, 9...on/off valve Patent applicant Honda Motor Co., Ltd.

Claims (1)

[Claims] An exhaust system in which a main exhaust pipe connected to the exhaust port of the engine is branched into a first and second exhaust branch pipe; a main intake pipe connected to the intake port of the engine is divided into a first and second exhaust branch pipe; an intake system branched into a second intake branch pipe; a first turbo supercharger interposed between the first exhaust branch pipe and the first intake branch pipe; the second exhaust branch pipe and the second intake branch pipe; a second turbo supercharger interposed between the branch pipe;
A supercharging device for an engine, comprising an on-off valve that is interposed in the middle of the second exhaust branch pipe and opens when the internal pressure in the first intake branch pipe exceeds a set value.