JPH1193715A - Internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recirculate an exhaust gas at a low cost by providing an exhaust gas recirculating valve opening mechanism for slightly opening an exhaust port to suck the exhaust gas into a cylinder when the exhaust pressure is higher than the intake pressure in intake process. SOLUTION: When the exhaust valve cam 23 of an exhaust valve recirculation switching device 22 is rotated, a bush rod 25 is raised and lowered, a rocker arm 19 is reciprocated and tilted around the eccentric part 18 of a rocker shaft 17, and an exhaust valve 10 contact with the rocker arm 19 is raised and lowered to open and close an exhaust port 32. The exhaust valve opening and closing cam 23 has a slight exhaust gas recirculating lift 27 provided in the part where the exhaust pressure in an intake are 28 is higher than the intake pressure, and the exhaust valve 10 is lowered in this part to slightly open the exhaust port 32. When the exhaust port 32 is slightly opened in the pressure reversed part where the exhaust pressure in an intake area 26 is higher than the intake pressure, an exhaust gas 9 is forcedly sucked into a cylinder 8 by a differential pressure since the exhaust pressure is higher than the intake pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine, and more particularly, to an internal combustion engine capable of achieving exhaust gas recirculation at low cost.

[0002]

2. Description of the Related Art In an internal combustion engine such as an automobile engine,
2. Description of the Related Art Exhaust gas recirculation is performed by mixing a part of exhaust gas with intake air to suppress combustion and thereby reduce the amount of generated nitrogen oxides and the like.

A conventional internal combustion engine in which exhaust gas recirculation is performed is as shown in FIG.

In FIG. 1, reference numeral 1 denotes a turbocharger, 2 denotes a compressor of the turbocharger 1, 3 denotes air to be taken in and compressed by the compressor 2 of the turbocharger 1, and 4 denotes an intercooler for cooling the air.

[0005] 5 is an intake manifold, 6 is an intake valve of the engine 7, 8 is a cylinder of the engine 7, 9 is exhaust gas from the engine 7, 10 is an exhaust valve of the engine 7, 1
Reference numeral 1 denotes an exhaust manifold, and 12 denotes a turbine of the turbocharger 1.

An exhaust gas recirculation passage 13 is provided between the intake manifold 5 and the exhaust manifold 11.
Reference numeral 14 denotes an exhaust gas recirculation valve provided in the exhaust gas recirculation passage 13.

Reference numeral 15 denotes a piston of the engine 7, and 16 denotes a connecting rod.

According to the above configuration, first, the compressor 3 of the turbocharger 1 sucks and compresses the air 3, guides the compressed air 3 by the compressor 2 to the intercooler 4, cools it, and cools it by the intercooler 4. The air 3 (compressed air) is sent to the intake manifold 5, and the air 3 is distributed and supplied from the intake manifold 5 to each cylinder 8 of the engine 7 via the intake valve 6. Are mixed and burned.

Exhaust gas 9 generated by combustion in each cylinder 8 is passed through an exhaust valve 10 to an exhaust manifold 11.
The exhaust gas 9 collected in the exhaust manifold 11 is sent to the turbine 12 of the turbocharger 1 to drive the turbine 12, and the heat of the exhaust gas 9 as a power source of the compressor 2 of the turbocharger 1. After collecting energy, release it to the atmosphere.

A part of the exhaust gas 9 collected in the exhaust manifold 11 is sent to the intake manifold 5 through the exhaust gas recirculation passage 13 by opening the exhaust gas recirculation valve 14, and the intake manifold 5 is opened. The exhaust gas is mixed with the air 3 in the inside to recirculate the exhaust gas.

As a result, combustion is suppressed, and thus the amount of generated nitrogen oxides and the like is reduced.

[0012]

However, the conventional internal combustion engine has the following problems.

That is, since the exhaust gas recirculation passage 13 and the exhaust gas recirculation valve 14 are provided between the exhaust manifold 11 and the intake manifold 5, the configuration of the apparatus becomes large and the cost is increased accordingly. And the exhaust gas recirculation passage 13 in the engine room.
In addition, there are also problems in installation such as the layout of the equipment.

An object of the present invention is to provide an internal combustion engine capable of achieving exhaust gas recirculation at a low cost in view of the above situation.

[0015]

SUMMARY OF THE INVENTION In the intake stroke, when the exhaust pressure becomes higher than the intake pressure, an exhaust port 32 is provided.
The internal combustion engine is provided with an exhaust gas recirculation valve-opening mechanism 28 that slightly opens the exhaust gas 9 so that the exhaust gas 9 is sucked into the cylinder 8.

According to the above means, the following effects can be obtained.

In the intake stroke, when the exhaust pressure becomes higher than the intake pressure, the exhaust port 32 is slightly opened by the exhaust gas recirculation valve opening mechanism 28 so that the exhaust gas 9 is sucked into the cylinder 8. By doing so, it is possible to achieve exhaust gas recirculation.

As described above, according to the present invention, the exhaust gas can be recirculated with a simple configuration, and the cost can be reduced.

Further, since the exhaust gas recirculation valve opening mechanism 28 can be mounted in the engine, the problem of installation can be solved.

[0020]

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

FIGS. 1 to 3 show an embodiment of the present invention.

The basic structure of an internal combustion engine such as an engine is the same as that shown in FIG. 4, and the same parts are denoted by the same reference numerals and description thereof will be omitted.

In the present invention, an eccentric portion 18 is formed on a rocker shaft 17 provided on the upper portion of the engine 7, and a rocker arm 19 is pivotally supported on the eccentric portion 18 so as to be rotatable.
A link rod 20 is attached to the rocker shaft 17, and an actuator 21 such as an air cylinder for moving the center of the rocker arm 19 up and down by rotating the link rod 20 with the push rod 25 as a fulcrum is connected. The device 22 is configured.

The exhaust valve 10 is attached to one end of the rocker arm 19, and a push rod 25 provided with a tappet 24 that is slidably contacted with an exhaust valve opening / closing cam 23 is attached to the other end of the rocker arm 19. A small amount of the exhaust gas recirculation lift 2 is provided at a portion where the exhaust pressure is higher than the intake pressure in the intake region 26 of the opening / closing cam 23.
7, the exhaust gas recirculation valve opening mechanism 28 is formed.

Reference numeral 29 denotes a compression area of the exhaust valve opening / closing cam 23, reference numeral 30 denotes an expansion area of the exhaust valve opening / closing cam 23, 31
Is an exhaust area of the exhaust valve opening / closing cam 23, and 32 is an exhaust port.

Next, the operation will be described.

First, an actuator 21 such as a cylinder constituting the exhaust gas recirculation switching device 22 is contracted as shown in FIG. 1 to a solid line state, and the rocker shaft 17 is rotated through a link rod 20 by a required angle. Then, the eccentric portion 18 of the rocker shaft 17 is moved downward to bring the rocker arm 19 into the normal operation state shown by the solid line.

When the exhaust valve opening / closing cam 23 is rotated in this state, the push rod 25 is moved up and down by the exhaust valve opening / closing cam 23, and the rocker arm 19 is moved up and down by the push rod 25 to move the eccentric portion 1 of the rocker shaft 17.
The exhaust valve 10 that is reciprocated about the center 8 and is in contact with the rocker arm 19 is moved up and down to open and close the exhaust port 32.

More specifically, the exhaust valve opening / closing cam 23
In the compression region 29 and the expansion region 30, no lift is formed, so that the push rod 25 is not lifted via the tappet 24, and therefore, the exhaust valve 10 keeps the exhaust port 32 closed. ing.

Next, since a large lift is formed in the exhaust area 31 of the exhaust valve opening / closing cam 23, the push rod 25 is lifted via the tappet 24, and the rocker arm 19 moves the eccentric part 18 of the rocker shaft 17 to the eccentric part 18. It tilts clockwise in the figure as the center, and the exhaust valve 10 attached to one end of the rocker arm 19 is lowered, so that the exhaust port 3
Open 2 Thereby, exhaust is performed.

In the intake area 26 of the exhaust valve opening / closing cam 23, since there is usually no lift, the exhaust port 32 is closed as in the compression area 29 and the expansion area 30. However, in the case of the present invention, a slight exhaust gas recirculation lift 27 is provided in a portion where the exhaust pressure in the intake region 26 is higher than the intake pressure, and the exhaust valve 10 is lowered in this portion. Then, the exhaust port 32 is slightly opened.

The operation of the exhaust valve 10 is shown in FIG. FIG. 2 is a graph showing the amount of elevation of the exhaust valve 10. According to FIG. 2, the exhaust valve 10 is located at a part of the intake region 26 as shown by the solid line A.
7, it can be seen that it is raised and lowered. In addition, the broken line B in FIG. 2 indicates the amount of elevation of the intake valve 10.

On the other hand, the exhaust manifold is
Since the exhaust from is merged alternately,
As shown by a solid line C in FIG. 3, the pressure is pulsating. Similarly, in the intake manifold, since the intake to each cylinder 8 is performed alternately, the pressure pulsates as shown by the broken line d in FIG. When the pressure of the pulsating exhaust manifold (exhaust pressure) and the pressure of the pulsating intake manifold (intake pressure) are superimposed and compared as shown in FIG. 3, the pressure of the exhaust manifold is It can be seen that a phenomenon in which the intake manifold pressure alternately reverses occurs regularly. Therefore, when the phenomenon in which the pressure alternately reverses was examined, it was found that the exhaust pressure was higher than the intake pressure in the intake region 26, and a pressure reversal portion occurred.

Therefore, when the exhaust port 32 is slightly opened as described above in the reverse part of the pressure where the exhaust pressure in the intake region 26 becomes higher than the intake pressure, the exhaust pressure is higher than the intake pressure. The exhaust gas 9 is forcibly sucked into the cylinder 8 by the differential pressure, and by utilizing this, it is possible to easily achieve the exhaust gas recirculation.

As described above, exhaust gas recirculation is performed.
If the exhaust gas recirculation is performed when the engine 7 is under a high load, the amount of black smoke in the exhaust gas 9 generated due to lack of oxygen increases, and in such a case, the exhaust gas recirculation is performed. Is preferably not performed.

Therefore, in the present invention, an exhaust gas recirculation switching device 22 is provided so that whether or not to perform exhaust gas recirculation can be selected and arbitrarily switched.

That is, when the exhaust gas recirculation is not performed, the actuator 21 such as a cylinder constituting the exhaust gas recirculation switching device 22 is extended and extended as shown in FIG. Then, the rocker shaft 17 is rotated by a required angle via the link rod 20, the eccentric portion 18 of the rocker shaft 17 is moved upward, and the rocker arm 19 is entirely lifted upward as shown by a virtual line. I do.

Then, the exhaust valve 10 is lifted up together with the rocker arm 19, so that the valve lift of the exhaust valve 10 is as shown by the solid line E in FIG. The exhaust valve 10 is not lowered by the recirculation lift 27 and the exhaust port 32 is not opened, so that the exhaust gas recirculation can be stopped.

As described above, according to the present invention, the exhaust gas can be recirculated with a simple structure, and the cost can be reduced.

Further, by using the exhaust gas recirculation switching device 22, it is possible to arbitrarily switch whether or not to perform the exhaust gas recirculation.

Further, since the exhaust gas recirculation valve opening mechanism 28 and the exhaust gas recirculation switching device 22 are mounted in the engine 7, the installation problem can be solved.

It should be noted that the present invention is not limited to the above-described embodiment, but is not limited to the OHV engine.
It goes without saying that various changes can be made without departing from the spirit of the present invention as well as being applicable to the C engine.

[0043]

As described above, according to the internal combustion engine of the present invention, there is an excellent effect that exhaust gas recirculation can be achieved at low cost.

[Brief description of the drawings]

FIG. 1 is a partially enlarged side view of an example of an embodiment of the present invention.

FIG. 2 is a graph showing the amount of elevation of an intake valve and an exhaust valve.

FIG. 3 is a graph showing changes in intake pressure and exhaust pressure.

FIG. 4 is an overall schematic route diagram of a conventional example.

[Explanation of symbols]

 8 Cylinder 9 Exhaust gas 28 Exhaust gas recirculation valve opening mechanism 32 Exhaust port

Claims (1)

[Claims] In the intake stroke, when the exhaust pressure becomes higher than the intake pressure, the exhaust gas (9) is sucked into the cylinder (8) by slightly opening the exhaust port (32). An internal combustion engine provided with an exhaust gas recirculation valve opening mechanism (28).