JPH0619807Y2 - Engine scavenger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to an engine scavenging device for scavenging residual exhaust gas in a cylinder.

[Prior Art and its Problems] Generally, in the exhaust stroke of the engine, a part of the exhaust gas remains in the cylinder without being discharged. This residual exhaust gas is
A high temperature and a high load operation of the engine cause a high temperature and cause knocking. Therefore, a method of scavenging the engine has been proposed.

As one of the methods of this kind, a small air pump driven by the engine is provided, and the air pressurized by the air pump is pushed into the combustion chamber at the end of the exhaust stroke, and the exhaust gas that tends to remain in the cylinder is exhausted from the exhaust port. There is proposed one that is positively pushed out (Japanese Patent Laid-Open No. 59-1059).
No. 26).

This method can improve scavenging performance, but
Since the pump itself becomes a load on the engine, the load on the engine increases, and it is difficult to control the scavenging amount.

[Object of the Invention] The object of the present invention is to improve the scavenging property of each cylinder without specially providing a forced scavenging means such as a pump.

Therefore, according to the present invention, in a multi-cylinder engine equipped with a supercharger, each cylinder constituting the multi-cylinder engine is provided with an auxiliary port in addition to an intake port and an exhaust port, and an auxiliary port for each cylinder is provided. While providing a communication passage that communicates the port with the auxiliary ports of other cylinders in a predetermined relationship,
An auxiliary opening / closing valve that opens at least in the latter part of the exhaust stroke and in the early part of the compression stroke is provided, and at the end of the exhaust stroke of each cylinder, the high pressure generated in the other cylinder is made to act on that cylinder via the communication passage and the auxiliary port. Further, the present invention provides a scavenging device for an engine, which is provided with a control valve for shutting off the communication between the cylinders through the communication passage when the engine has a light load.

[Advantages of the Invention] According to the present invention, since the high pressure generated in other cylinders can be applied to the cylinder at the end of the exhaust stroke when the engine has a high load, the scavenging property for the residual exhaust gas can be improved and While improving the knocking property,
While a high compression ratio can be achieved, combustibility can be ensured by interrupting communication between the cylinders and stopping scavenging when the load is light.

[Embodiment] Hereinafter, an embodiment of the present invention will be specifically described with reference to the accompanying drawings.

As shown in FIG. 1, in an engine E including an exhaust turbocharger and including first to fourth cylinders # 1 to # 4, an intake port 2 opening to a combustion chamber 1 of each cylinder has a branch intake passage. 4 is communicated with the surge tank 5 via air, and air is supplied to the combustion chamber 1 according to the opening degree of the throttle valve 7 provided in the common intake passage 6 upstream of the surge tank 5 in the intake stroke.
Inhale. In the exhaust stroke in which the exhaust port 8 of each cylinder is opened, the exhaust gas in the combustion chamber 1 is exhausted from the branch exhaust passage 9 to the collective exhaust passage 10 by the piston rising.

In the combustion chamber 1 of each cylinder, the intake and exhaust ports 2 and 8 are provided.
In addition, the auxiliary intake port 11 as the auxiliary port referred to in the present invention is opened. And the auxiliary intake port 11
Indicates the auxiliary intake port 11-1 of the first cylinder # 1 whose ignition order is not continuous (note that the number after being connected by a hyphen is the cylinder number. The same applies to the following. However, since it is difficult to enter in the drawing, the description is omitted. .) And the auxiliary intake port 11-4 of the fourth cylinder # 4 through the first communication passage 12 and the second cylinder # 4.
The second auxiliary intake port 11-2 and the auxiliary intake port 11-3 of the third cylinder # 3 are communicated with each other through the second communication passage 13.

As shown in FIGS. 2A to 2D, the valve opening / closing timings of the first cylinder # 1 and the fourth cylinder # 4, which are communicated by the first communication passage 12, are shown respectively.
Auxiliary intake valve G ₁₁ for opening and closing the ~11-4, ..., G ₁₁ is,
The opening / closing timing is set so as to open earlier and close later than the main intake valves G ₁₂ , ..., G ₁₂ that open and close the intake ports 2-1 to 2-4, respectively.

If the valve timing is set as described above, in the compression stroke of the first cylinder # 1 in which the piston turns upward at the crankshaft rotation angle of 180 ° and the main intake valve G ₁₂ is closed,
Before the auxiliary intake valve G ₁₁ is closed, the first communication passage 1
The air compressed as the piston moves upward is stored in No. 2, and the compressed air stored in the first communication passage 12 opens the auxiliary intake valve G _{11 at the} end of the exhaust stroke of the fourth cylinder # 4. At this time, the exhaust gas that flows from the auxiliary intake port 11-4 into the combustion chamber 1 at a high pressure and tends to remain in the combustion chamber 1-4 is exhausted from the exhaust port 8-4 to the branch exhaust passage 9.
-4 to scaveng the combustion chamber 1-4 of the fourth cylinder # 4.

Next, as shown in FIG. 2 (d), the crankshaft rotation angle 5
In the compression stroke of the fourth cylinder # 4 after 40 °, compressed air is stored in the first communication passage 12 while the auxiliary intake valve G ₁₁ is opened, and the stored compressed air is stored in the first cylinder. #
No. 1 exhaust port 8-1 and auxiliary intake port 11-1 overlap each other at the time of intake / exhaust overlap, the exhaust gas that flows into the combustion chamber 1-1 of the first cylinder # 1 vigorously and remains It is pushed out from the combustion chamber 1-1 and scavenged.

Also for the second cylinder # 2 and the third cylinder # 3, the phase difference between the two cylinders is 360 ° in crank angle,
Similar to the connection between the first and fourth cylinders # 1 and # 4, the second communication passage 13
The scavenging of the inside of the combustion chamber 1 by the compressed air is performed through.

By the way, in an engine equipped with a supercharger, the compression pressure itself also rises due to the influence of the supercharging pressure, so the pressure of the compressed air generated in the communication passages 12 and 13 also becomes high, and the scavenging effect is obtained in the light load region. It becomes too strong, and the effect of temperature rise due to residual exhaust gas cannot be expected, which may lead to deterioration of combustion. Therefore, in the present embodiment, as shown in FIG. 1, the opening / closing control valve 18-is provided at the communication portion of the first and second communication passages 12 and 13 to the auxiliary intake ports 11-1, ..., 11-4.
1, ..., 18-4 are provided, are supported by a common drive shaft 19, and the drive shaft 19 is drive-controlled by an actuator 20.

In that case, each on-off control valve 18 is, as shown in FIG.
When the load is light, the valve is fully closed, and when the load is increased from a low load, the opening is increased according to the increase, and the valve is controlled to be fully opened in the high speed and high load region. As a result, when the load is light, the scavenging is stopped by giving priority to the combustibility, and the scavenging is performed when the load becomes higher than a certain level.At a high speed and a high load, a sufficient scavenging effect is obtained. It is possible to improve the knock resistance and achieve a substantially higher compression ratio.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an engine according to an embodiment of the present invention, FIG. 2 (a), FIG. 2 (b), FIG. 2 (c), and FIG.
FIG. 3D is a timing chart showing the valve timings of the main intake valve, the auxiliary intake valve, and the exhaust valve of the first to fourth cylinders, respectively, and FIG. 3 is a graph showing the control characteristics of the opening / closing control valve of FIG. . 1 ... Combustion chamber, 2 ... Intake port, 8 ... Exhaust port, 11 ... Auxiliary intake port, 12, 13 ... First and second communication passages, 17 ... Supercharger, 18-1, ..., 18-4 ... Control valve, 20 ... actuator, G _12, ..., G ₁₂ ... main intake valve, G _11, ..., G ₁₁ ... auxiliary air intake valve.

Claims (1)

[Scope of utility model registration request] 1. A multi-cylinder engine equipped with a supercharger,
Each cylinder of the multi-cylinder engine is provided with an auxiliary port in addition to the intake and exhaust ports, and a communication passage for communicating the auxiliary port of each cylinder with the auxiliary ports of other cylinders in a predetermined relationship. An auxiliary opening / closing valve is provided to open each auxiliary port at least in the latter half of the exhaust stroke and in the early stage of the compression stroke, and at the end of the exhaust stroke of each cylinder, the high pressure generated in another cylinder is passed through the communication passage and the auxiliary port. A scavenging device for an engine, characterized in that a control valve is provided for shutting off the communication between the cylinders through the communication passage when the engine has a light load.