JPH04143449A - Exhaust gas recirculation system for internal combustion engine - Google Patents

Abstract

PURPOSE:To reduce the generation of NOx and keep off any power drop by installing an air chamber interconnected to the inside of a cylinder of an internal combustion engine and also an on-off valve, intermitting an interconnected state between the cylinder and the air chamber, while setting up a valve opening mechanism for this on-off valve interlocking with driving of the engine. CONSTITUTION:An air chamber 24, interconnected to a cylinder 14 via an interconnected passage 23, is formed in a cylinder 13, and an on-off valve 25, opening or closing this interconnecting passage 23, and a valve opening mechanism 35 interlocking with drive of an internal combustion engine both are attached to the cylinder head 13. This on-off valve 25 is opened at time of the first half compression stroke as well as at time of the latter half explosion stroke. With the on-off valve 25 opened at the latter half of the explosion stroke, a part of exhaust gas is stored in the air chamber 24, then in this state, after a suction stroke is ended, it shifts to the compression stroke, and at the first half compression stroke, the on-off valve 25 is opened and the exhaust gas stored in the air chamber 24 is discharged into the cylinder 14. With this discharge, oxygen content in compressed air goes down so that a combustion temperature at time of the explosion stroke also goes down. On the other hand, release of the exhaust gas into the cylinder 14 is carried out after the suction stroke is ended, so the absolute value of suction oxygen content is not reduced.

Description

[Detailed description of the invention] Industrial applications The present invention relates to an exhaust gas recirculation device for an internal combustion engine.

Conventional technology Conventionally, in internal combustion engines, EGR (exhaust gas recirculation) has been generally performed to reduce the oxygen concentration in order to reduce 'NOx' in the exhaust gas. An explanation will be given based on Fig. 4. First, a multi-cylinder diesel engine is provided with an intake manifold 1 and an exhaust manifold 2. One end of an intake pipe 3 is connected to the intake manifold 1. An air cleaner 4 is connected to the other end.

On the other hand, one end of an exhaust pipe 5 is connected to the exhaust manifold 2, and a muffler 6 is connected to the other end of the exhaust pipe 5.

Next, an exhaust gas recirculation passage 7 is provided, one end of which is connected to the middle of the exhaust pipe 5 and the other end of which is connected to the other end of the intake pipe 3.
A valve 8 whose opening degree can be freely adjusted is provided in the middle. Note that a controller 1 is used to adjust the opening degree of the valve 8 based on signals from the rotation sensor 9 and the load sensor 10.
1 is provided.

In such a configuration, air sucked from the air cleaner 4 passes through the intake pipe 3 and the intake manifold 1 and is sucked into the cylinder. Then, fuel is injected into the compressed air compressed within the cylinder, and the explosion stroke begins, and the generated exhaust gas is discharged into the atmosphere via the exhaust manifold 2, exhaust pipe 5, and muffler 6.

Here, the opening degree of the valve 8 is adjusted by the controller 11 based on signals from the rotation sensor 9, the load sensor 10, etc., and a part of the exhaust gas flowing in the exhaust pipe 5 passes through the exhaust gas recirculation passage 7 to the intake air. It is fed into pipe 3. As a result, the amount of air taken in from the air cleaner 4 decreases, the oxygen concentration within the cylinder decreases, the combustion temperature decreases, and the amount of NOx generated decreases.

Problems to be Solved by the Invention However, there is a drawback that the output is reduced due to a reduction in the absolute amount of oxygen in the air sucked into the cylinder.

In addition, since the exhaust gas that is recirculated and supplied into the intake pipe 3 contains sludge such as smoke,
This sludge accumulates on the intake pipe 3, intake manifold 1, intake boat in each cylinder, etc., and the intake passage is narrowed, resulting in a decrease in the amount of intake air and a decrease in output.

Furthermore, in order to recirculate the exhaust gas, an exhaust gas recirculation passage 7, a valve 8, a controller 11, a sensor 9,
10 etc. is required, resulting in high cost.

Furthermore, the sludge in the exhaust gas comes into contact with the inner surface of the cylinder during the suction stroke and the compression stroke, resulting in increased wear on the inner surface of the cylinder and the piston ring.

Means for Solving the Problem An air chamber communicated with the inside of a cylinder of an internal combustion engine, and an on-off valve for opening and closing communication between the inside of the cylinder and the air chamber are provided, and an explosion occurs in conjunction with the operation of the internal combustion engine. The valve opening mechanism operates in conjunction with the operation of the internal combustion engine, and opens the on-off valve during the latter half of the explosion stroke. is opened and a portion of the exhaust gas is stored in the air chamber. Further, the on-off valve is opened again during the latter half of the suction stroke or the first half of the compression stroke, and the stored exhaust gas is discharged into the cylinder.

Therefore, the absolute amount of oxygen drawn into the cylinder does not decrease, but the oxygen concentration decreases. Therefore, as the oxygen concentration decreases, the combustion temperature decreases, and the amount of NOx generated decreases, and since the absolute amount of oxygen does not decrease, the output does not decrease.

Embodiment An embodiment of the present invention will be explained based on FIGS. 1 to 3. First, the cylinder head 13 is attached to the cylinder block 12.
A cylinder 14 of an internal combustion engine is provided, in which a piston 15 is slidably provided within the cylinder 14, and a piston ring 16 is attached to the outer periphery of the top side of the piston 15. The cylinder head 13 is formed with an intake boat 17 and an exhaust port 18, and is further provided with an intake valve 19 for opening and closing the intake boat 17 and an exhaust valve 20 for opening and closing the exhaust port 18. A fuel injection valve 22 for injecting fuel into a combustion chamber 21 formed at the top of the cylinder 14 is attached to the cylinder head 13.

Furthermore, an air chamber 24 is formed in the cylinder head 13 and communicated with the inside of the cylinder 14 via a communication passage 23, and an on-off valve 25 for opening and closing the communication passage 23 is attached to the cylinder head 13. Note that the on-off valve 2
A spring 28 is attached to the top side of the valve 5, and the open/close valve 25 is closed by a spring 28 whose end is in contact with the retainer 27 and whose other end is in contact with the upper surface of the cylinder head 13. It is constantly biased in the direction. Further, an adjustment screw 29 is attached to the upper surface of the cylinder head 13 so as to be adjustable in its protrusion and retraction, and is fixed by a lock nut 30 at an arbitrary protrusion and retraction position.

Next, a rocker arm 31 is provided, one end of which rotatably contacts the top of the adjustment screw 29 and the other end of which contacts the top of the on-off valve 25. A roller 33 is rotatably held in a bin 32 provided at the center. The outer circumferential surface of the roller 33 is in contact with the outer circumferential surface of a cam 34 that rotates in conjunction with the operation of the internal combustion engine.
Previously, the adjustment screw 29 and rocker arm 31
The roller 33, cam 34, etc. constitute a valve opening mechanism 35 that opens the on-off valve 25 at a predetermined timing.

In such a configuration, as shown in the timing chart of FIG. 3, during operation of the internal combustion engine, each stroke is repeated in the order of suction, compression, explosion, and exhaust, and the on-off valve 25 is operated during the first half of the compression stroke and the second half of the explosion stroke. The valve is opened at the time. A portion of the exhaust gas is stored in the air chamber 24 by opening the on-off valve 25 during the latter half of the explosion stroke.

Next, a part of the exhaust gas is stored in the air chamber 24 and sucked into the cylinder 14, and after the suction stroke is completed, the compression stroke begins, and the on-off valve 25 is opened again during the first half of the compression stroke. By opening the valve, the exhaust gas stored in the air chamber 24 is released into the cylinder 14.

Here, as the exhaust gas is released into the cylinder 14, the oxygen concentration in the compressed air in the cylinder 14 decreases, and the combustion temperature during the lighting process decreases, causing "NOx
” will be reduced.

On the other hand, since the exhaust gas is released into the cylinder 14 after the suction stroke ends, the absolute amount of oxygen taken in during the suction stroke does not decrease, and the output does not decrease.

In addition, the recirculating exhaust gas does not pass through the intake passage, and the sludge contained in the exhaust gas does not accumulate in the intake passage, so there is no throttling due to sludge accumulation, and this throttling prevents the intake air from flowing. This prevents the output from decreasing. Furthermore, since the sludge in the exhaust gas discharged into the cylinder 14 comes into contact with the inner peripheral surface of the cylinder 14 only during the compression stroke, compared to the conventional example where the sludge comes into contact with the inner peripheral surface of the cylinder 14 even during the intake stroke. This reduces wear on the cylinder 14 and piston ring 16.

Moreover, the cost is reduced because the exhaust gas recirculation passage 7, sensors 9, 10, controller 11, etc. used in the conventional example for recirculating exhaust gas are no longer necessary.

In this embodiment, the explanation has been given by taking as an example the valve opening mechanism 35 that releases the exhaust gas stored in the air chamber 24 into the cylinder 14 by opening the on-off valve 25 during the first half of the compression stroke. The exhaust gas in the air chamber 24 may be released into the cylinder 14 by opening the on-off valve 25 during the latter half of the intake stroke. Even in this case, the absolute amount of oxygen sucked into the cylinder 14 hardly decreases, and a decrease in output due to a decrease in the absolute amount of oxygen does not occur.

Effects of the Invention As described above, the present invention allows a part of the exhaust gas to be stored in the air chamber by opening the on-off valve using the valve-opening mechanism in the latter half of the explosion stroke, and furthermore, in the latter half of the suction stroke or during the compression stroke. By opening the on-off valve using the valve-opening mechanism in the latter half of the stroke, the stored exhaust gas can be released into the cylinder.Therefore, the oxygen concentration of the air compressed in the cylinder decreases, which lowers the combustion temperature. At the same time, it is possible to reduce the amount of If N Q This prevents the sludge contained in the exhaust gas from accumulating in the intake passage and obstructing the intake air. Since the cylinder contacts the circumferential surface mainly only during the compression stroke, it has the effect of reducing wear on the inner circumferential surface of the cylinder, piston rings, etc. due to sludge compared to the conventional example.

[Brief explanation of drawings]

Figures 1 to 3 show one embodiment of the present invention, with Figure 1 being a longitudinal sectional front view, Figure 2 being a bottom view showing the arrangement of intake valves, exhaust valves, and on-off valves, and Figure 3 being a bottom view showing the arrangement of intake valves, exhaust valves, and on-off valves. is a timing chart showing the opening/closing timing of intake valves, exhaust valves, on-off valves, etc.
FIG. 4 is an explanatory diagram of EGR in a conventional example. I4...Cylinder, 24...Air chamber, 25...Opening/closing valve, 35...Valve opening mechanism Applicant Ishikawajima Shibaura Machine Co., Ltd. 7 Figures

Claims (1)

[Claims] An air chamber that communicates with the inside of a cylinder of an internal combustion engine and an on-off valve that connects and disconnects communication between the inside of the cylinder and the air chamber are provided. An exhaust gas recirculation device for an internal combustion engine, characterized in that the exhaust gas recirculation device for an internal combustion engine is provided with a valve opening mechanism that opens the on-off valve at the first half of the compression stroke or during the first half of the compression stroke.