JPH031488B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an engine supercharging device.

Generally, a supercharging device for an engine is used to supply air or air-fuel mixture under pressure to a combustion chamber to improve its charging efficiency and increase engine output. Conventionally, supercharging devices for this engine include those in which a supercharger is provided in a single intake passage to supply all intake air under pressure, and one in which a supercharger is provided in a single intake passage to supply all the intake air under pressure. There is a so-called partial supercharging system in which a second intake passage having a feeder is provided, and the intake port of the second intake passage is opened at least during the compression stroke (Japanese Patent Application Laid-Open No.
(See Publication No. 55-137314). Among these, the former requires a larger supercharger in order to perform supercharging efficiently, whereas the latter, that is, a partial supercharging type, has the advantage that a small supercharger is sufficient.

However, in this conventional partial supercharging engine supercharging system, the closing timing of the second intake passage cannot be unnecessarily delayed due to the relationship with the supercharger capacity, ignition timing, etc. It was necessary to make the opening times of both the first and second intake passages overlap. Then, when the engine is under high load and at low engine speeds, the supercharging pressure from the second intake passage becomes high, but the inertia of the intake air flowing through the first intake passage is small. There was a problem in that air was blown back into the intake passage, wasting the supply of supercharging air, and reducing supercharging efficiency.

Incidentally, the inertia of the intake air flowing through the first intake passage increases as the engine speed increases, and the amount of air blown back from the second intake passage to the first intake passage depends on the intake inertia of the first intake passage. The smaller the number, the greater the increase. Therefore, when the engine is running at high speeds, the blowback to the first intake passage does not pose much of a problem.

This invention was made in view of the above-mentioned circumstances, and in the above-mentioned partially supercharged supercharged engine, in the high load region of the engine, the first intake passage is closed and the first intake passage is closed at low engine speeds. By supplying only supercharging air from the second intake passage, and supplying fresh air from the first intake passage in addition to the supercharging air when the engine is running at high speeds, it is possible to reduce the driving loss of the supercharger. The object of the present invention is to provide an engine supercharging device that can improve output performance without impairing supercharging efficiency.

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

The drawing shows an engine supercharging device according to an embodiment of the present invention. In the figure, reference numeral 1 is an engine composed of a cylinder 2 and a piston 3 that reciprocates within the cylinder 2.In the cylinder 2 of the engine 1, combustion is carried out by the inner surface of the cylinder 2 and the upper surface of the piston 3. A chamber 4 is formed, and a crankshaft 6 is connected to the piston 3 via a connecting rod 5.

Further, the combustion chamber 4 is provided with an exhaust port 7a, a first intake port 8a, and a second intake port 9a, each of which is open. Above exhaust port 7
a communicates with the exhaust passage 7, and the exhaust port 7
A is provided with an exhaust valve 10 for opening and closing it. Further, the first intake port 8a communicates with the first intake passage 8, and the first intake port 8a is provided with a first intake valve 11 that opens and closes it.

Further, the second intake port 9a communicates with the second intake passage 9, and the second intake port 9a
is provided with a second intake valve 12, the intake valve 12
The port 9a is opened at the end of the intake stroke and closed at the compression stroke. Further, a fuel injection valve 1 is located in the middle of the second intake passage 9.
3 is provided. A blower 14 is provided further upstream of the second intake passage 9, while a turbine 15 is provided in the middle of the exhaust passage 7. The blower 14 and the turbine 15 are interconnected by a shaft 16. A turbo supercharger 17 is configured. In addition, both the first and second intake passages 8,
The other end of 9 is connected to one intake passage 18, and an accelerator pedal (not shown) is provided in the middle of the intake passage 18.
A throttle valve 19 is provided which operates in conjunction with.
Further upstream of this intake passage 18, a measuring plate type air flow sensor 20 for detecting the amount of intake air is provided, and further upstream thereof is an air cleaner 21. In the figure, 22 is a potentiometer that detects the amount of intake air from the rotation angle of the measuring plate of the air flow sensor 20, 23 is a rotation speed sensor that detects the engine rotation speed, and 24 is the potentiometer 22 and the rotation speed. This is an injection amount control device that receives both outputs from the sensor 23 and applies a control signal to the fuel injection valve 13 so as to inject an amount of fuel determined based on the intake air amount and engine rotational speed.

An on-off valve 25 is rotatably disposed in the middle of the first intake passage 8, and the shaft 2 of the on-off valve 25
One end of a rod 27 is connected to the link 26 fixed to 5a, and the other end of the rod 27 is fixed to the surface of the diaphragm 29 of the diaphragm device 28 on the first chamber 30 side. This diaphragm device 28
A spring member 32 for pulling the diaphragm 29 to the left in the drawing is disposed in the second chamber 31 of the diaphragm 29, and a spring member 32 is disposed between the second chamber 31 and the downstream side of the supercharger 17 of the second intake passage 9. A pressure introduction passage 33 for introducing side pressure into the second chamber 31 is provided.

Next, the operation will be explained.

In the low engine load range, the throttle valve 19
The opening degree of the throttle valve 19 is relatively small, and the air from the air cleaner 21 is sucked into the intake passage 18 in an amount corresponding to the opening degree of the throttle valve 19. At this time, the amount of air taken into the intake passage 18 is small, and therefore the exhaust flow rate of the engine is also small, so the driving force applied to the turbine 15 of the supercharger 17 is extremely small, and almost no driving force is generated in the blower 14. do not have.
Then, the intake air is not pressurized by the blower 14 and is transferred to the second air stream only by the negative pressure of the engine.
The fuel is mixed with the injected fuel from the fuel injection valve 13, and is naturally sucked into the combustion chamber 4 when the second intake valve 12 is opened. At this time, the downstream pressure of the blower 14 of the supercharger 17 is a negative pressure, so the pressure introduced into the second chamber 31 in the diaphragm device 28 is below the set value. Then, the diaphragm 29 is deformed and moved to the left in the figure by the spring force of the spring member 32, and the rod 27 is pulled to the left, so the on-off valve 25 is closed, and the intake air is transferred from the first intake passage 8 to the combustion chamber. 4 will not be inhaled.

In this way, in the low load region of the engine, the air-fuel mixture from the second intake passage 9 is naturally drawn into the combustion chamber 4 from the end of the intake stroke to the compression stroke due to the negative pressure of the engine, and the air-fuel mixture is naturally sucked into the combustion chamber 4 from the end of the intake stroke to the compression stroke. Good operating conditions can be obtained.

Next, when the engine reaches a high load region, the opening degree of the throttle valve 19 increases, the amount of air taken into the intake passage 18 increases, the engine exhaust flow rate also increases, and the supercharging pressure of the supercharger 17 increases. increase In this way, when the engine is in a high load region and the engine speed is low, both the first and second intake passages 8,
If intake air or mixture is supplied from 9, the first
Since the intake inertia of the first intake passage 8 is small, the air blows back into the first intake passage 8 as described above, resulting in a driving loss of the supercharger 17. However, in this device, the supercharging pressure of the supercharger 17 is still below the set value in this case, and the diaphragm 29 of the diaphragm device 28 is sucked to the left by the spring force of the spring member 32, so the opening/closing is not possible. valve 2
5 is closed, and intake air from the first intake passage 8 is not supplied. Furthermore, in the second intake passage 9, since the supercharging pressure of the supercharger 17 is increasing, the air-fuel mixture is supplied to the combustion chamber 4 under pressure.

In this way, when the engine is in a high load region and the engine speed is low, the first intake passage 8 is closed and only the air-fuel mixture from the second intake passage 9 is supplied under pressure, and as a result, the first intake passage 8 is closed and only the air-fuel mixture from the second intake passage 9 is supplied under pressure. Air blowing back into the intake passage 8 of No. 1 does not occur, and driving loss of the supercharger 17 is reduced, charging efficiency is improved, and engine output is also improved.

When the engine speed increases in a high load region of the engine, even if both the first and second intake passages 8 and 9 are opened, the intake inertia of the first intake passage 8 increases, and the first intake passage Air blowing back into the 8 becomes less of a problem. Therefore, in this device, in this case, the supercharging pressure of the supercharger 17 exceeds the set value, and the diaphragm 29 in the diaphragm device 28 moves to the right in the figure due to the pressure introduced into the second chamber 31, so the on-off valve 25 opens. Then, the air from the air cleaner 21 is drawn into the first intake passage 8 by the negative pressure of the engine, and when the first intake valve 11 opens, it is naturally drawn into the combustion chamber 4, and the air is drawn into the second intake passage 8. The fuel enters the intake passage 9, is mixed with fuel from the fuel injection valve 13, and is supplied under pressure to the combustion chamber 4 when the second intake valve 12 is opened.

In this manner, when the engine is in a high load region and the engine speed is high, fresh air from the first intake passage 8 and mixture from the second intake passage 9 are supplied at least during the compression stroke. This further improves charging efficiency and engine output.

In the above embodiment, a turbo supercharger was used as the supercharger, but a mechanical supercharger may also be used. However, in this case, the supercharger hardly operates in the low load region of the engine and no intake air flows, so it is necessary to provide a bypass passage for the supercharger and open the bypass passage in the low load region. .

Further, in the above embodiment, the first intake passage is always closed in the low load region of the engine, but in this low load region, the supercharging pressure of the supercharger is low.
Since almost no air blows back into the first intake passage, the first intake passage may be opened.

Furthermore, in the above embodiment, the opening and closing of the first intake passage is controlled by the diaphragm device.
The present invention is not limited to the above embodiments,
For example, the opening and closing of the first intake passage may be electrically controlled depending on the engine load and engine speed.

As described above, according to the engine supercharging device according to the present invention, when the engine is in a high load region and the engine is running at low speed, the first intake passage is closed and the second intake passage is closed.
Only the supercharged air from the first intake passage is supplied under pressure, and when the engine is running at high speeds, the above supercharged air and fresh air from the first intake passage are supplied, thereby reducing drive loss of the supercharger. This has the effect of not only reducing fuel consumption but also improving charging efficiency and increasing engine output.

[Brief explanation of the drawing]

The drawing is a schematic configuration diagram of an engine supercharging device according to an embodiment of the present invention. 1... Engine, 8... First intake passage, 9...
...Second intake passage, 9a...Intake port.

Claims (1)

[Claims] 1. In an engine comprising a first intake passage and a second intake passage having a supercharger, the intake port constituting the second intake passage is opened at least during the compression stroke. In a high load region, when the engine is running at low speeds, the first intake passage is closed and the supercharger is supplied from the second intake passage, and when the engine is at high speeds, supercharging air is supplied from the second intake passage. A supercharging device for an engine, characterized in that it is configured to supply fresh air from the first intake passage.