JPH0416606B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust turbocharged four-stroke engine.

In conventional exhaust turbocharged four-stroke engines, two turbochargers are used, each consisting of a compressor and a turbine.
If the engine is equipped with at least one turbo supercharger, one (or more) of the turbo superchargers will stop operating in the low engine speed range, and a smaller number of turbo superchargers will be used.
A so-called one-turbo cut operation has been proposed that improves the performance of the engine in the low-speed range by performing a supercharging effect.

However, since the air supply pipe that receives the discharge air from multiple compressors is common, when turbocharger B, which is stopped at partial load, is started to operate as the engine speed increases, it is necessary to Since high pressure is maintained in the air supply pipe by the compressor of turbocharger A, the compressor of turbocharger B, which starts operating later, avoids backflow from the air supply pipe and surging phenomenon. Therefore, the discharged air cannot be sent to the air supply pipe until a certain rotation speed, and this requires a special switching device and time for switching, making it difficult to put this type of partial load performance improvement measure into practical use. It is hindering the development of

The object of the present invention is to focus on the above points, and to provide an exhaust turbocharged 4-cycle engine that can change the number of turbochargers operated according to the engine speed and load, and which can be easily and quickly switched. The main feature of this engine is to provide an exhaust turbocharged 4-stroke engine with two intake valves in each cylinder, which are configured to be able to maintain the valves closed for a required period of time during engine operation. A first air supply pipe that supplies air to the cylinder through one air supply valve of each cylinder, the other air supply valve of each cylinder, and a second air supply pipe that supplies air to the cylinder through one of the air supply valves of each cylinder. a trachea; at least one compressor directly connected to an exhaust turbine that supplies air to only one of the first and second air supply pipes; an exhaust gas for driving the compressor that supplies air to the second air supply pipe; An exhaust passageway between the turbine and the exhaust pipe of the engine is provided with an exhaust gate valve configured to keep the passageway closed while one of the intake valves of each of the cylinders is kept closed. That's what happened.

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

FIG. 1 is an explanatory diagram showing the main parts of an exhaust turbocharged four-stroke engine according to one embodiment of the present invention.

In the figure, 10 is the engine body, 11 is the cylinder head, 20 is the exhaust pipe, 21 is the exhaust valve, 31 is the first air supply pipe, 310 is the first air supply valve, 32 is the second air supply pipe, and 320 is the second air supply. air valve, 41 is the first turbine,
42 is a second turbine, 51 is a first compressor, 52 is a second compressor, 60 is an exhaust gate valve, and 70 is an air supply gate valve.

In this case, the present invention is applied to a four-cylinder engine.

The cylinder head 11 of each cylinder includes an exhaust valve 21, a first air supply valve 310, and a second air supply valve 3.
20 are provided. The exhaust gas from each exhaust valve 21 is discharged to the exhaust pipe 20.

The first air supply valve 310 receives air supply from the first air supply pipe 31, and the second air supply valve 320 receives air supply from the second air supply pipe 32 which is independent of the first air supply pipe 31.

The first compressor 51 transfers the discharged air to the first air supply pipe 3
1, and the second compressor 52 is connected to send the discharged air to the second air supply pipe 32.

Both the first turbine 41 and the second turbine 42 operate by receiving exhaust gas from the exhaust pipe 20, and are configured to drive the first compressor 51 and the second compressor 52, respectively, by direct connection or the like.

An exhaust passage between the exhaust pipe 20 and the second turbine 42 is formed by an exhaust gate valve 60, and an air supply passage between the second air supply pipe 32 and the second compressor 52 is formed by an air supply gate valve 70 (if necessary). The passages can be opened and closed by the sushi (not necessary).

Further, the second air supply valve 320 can be maintained in a closed state by stopping its normal opening and closing operation by appropriate means.

The operation in the case of the above configuration will be described.

When the engine is running at low speed, the exhaust gate valve 60 and the air supply gate valve 70 are closed, and the second air supply valve 320 is kept closed at all times.

Therefore, no exhaust gas is introduced into the second turbine 42, and the second turbine 42 and second compressor 52 do not operate at all.

Each cylinder of the engine receives supply air through the first compressor 51 → first intake pipe 31 → first intake valve 310,
The entire amount of exhaust gas introduced into the exhaust pipe 20 from the exhaust valve 21 is discharged from the first turbine 41.

When the engine rotates at high speed, the exhaust gate valve 60 and the air supply gate valve 70 are opened, and the second air supply valve 320 is opened and closed normally.

Therefore, in addition to the above-mentioned flow of air supply and exhaust air at low rotation speeds, air supply to each cylinder from the second compressor 52 and second air supply pipe 32, and exhaust air from the exhaust pipe 20 to the second turbine 42. An introduction is added.

The above case has the following effects.

When the engine speed increases, the exhaust gate valve 60 and the air supply gate valve 70 are opened to start operating the second turbine 42 and second compressor 52, which are stopped. The pressure inside the second air supply pipe 32 is kept sufficiently low, and the second air supply pipe 32
Backflow from the to the second compressor 52 side and the second compressor 52
There is no surging and very stable switching is possible.

Therefore, there is no need to set a complicated control mechanism or waiting time for this switching.

As described above, optimum supercharging conditions are provided for each of the low speed range and high speed range of the engine, so that the following performance improvement of the engine is achieved.

(1) Preventing smoke generation and improving acceleration in the low rotation range.

(2) Improved fuel efficiency and reduced heat load in the high rotation range.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the main parts of an exhaust turbocharged four-stroke engine according to the present invention. 11...Cylinder, 20...Exhaust pipe, 31...
First air supply pipe, 32...Second air supply pipe, 41...First
Turbine, 42...second turbine, 51...first
Compressor, 52...second compressor, 310...first air supply valve, 320...second air supply valve.

Claims (1)

[Claims] 1. In an exhaust turbocharged 4-cycle engine having two air intake valves in each cylinder, one air intake valve of each cylinder configured to be able to remain closed for a required period of time during engine operation; a first air supply pipe that supplies air to the cylinder via the other air supply valve of the cylinder; a second air supply pipe that supplies air to the cylinder via one of the air supply valves of each of the cylinders; and the first and second air supply pipes. at least one compressor directly connected to the exhaust turbine, each supplying air to only one of the above-mentioned second
In the exhaust passage between the exhaust turbine for driving the compressor, which supplies air to the air supply pipe of the engine, and the exhaust pipe of the engine, while one air supply valve of each cylinder is held in the closed state, the passage 1. An exhaust turbocharged four-stroke engine, comprising an exhaust gate valve configured to be able to maintain a closed state.