JPS6018610Y2 - Internal combustion engine exhaust gas recirculation control device - Google Patents

Description

[Detailed description of the invention] The present invention is an exhaust gas recirculation device that recirculates part of the exhaust gas to the intake system for the purpose of reducing NOx in the exhaust gas of an internal combustion engine. This invention relates to a device that controls the amount of exhaust gas according to the operating state of an engine.

Conventional control devices for exhaust gas recirculation systems have a diaphragm type recirculation control valve installed in the recirculation passage that connects the exhaust pipe and the intake passage. In conjunction with the provided sensing port, it is configured to open when the engine is idling and under full load, and the negative pressure from the sensing port is guided to the reflux control valve, and the reflux control valve is opened in conjunction with the opening and closing of the throttle valve. Therefore, when the engine load increases from a light load range, a relatively large amount of exhaust gas immediately circulates, making combustion unstable, especially in the low rotation range.

In order to avoid this situation, some models have an orifice installed in the negative pressure extraction passage from the sensing port to the recirculation control valve, but with this configuration, when the load increases, such as when accelerating with the throttle valve wide open, Since the recirculation control valve opens later than the increase in negative pressure at the sensing port, the response of the exhaust gas recirculation to increases in engine load is poor, and the effect of NOx reduction cannot be remotely estimated. .

In order to control the circulation of exhaust gas, the present invention uses two sensing ports in the carburetor, and when the throttle valve is opened from the idling position to a certain opening while the throttle valve is being fully opened, the control valve is momentarily activated. This prevents the throttle valve from opening and allows exhaust gas to be recirculated with a time delay, while if the throttle valve opens further, negative pressure from the sensing port is instantly introduced into the control valve to ensure responsiveness of exhaust gas recirculation. In addition, when the engine decelerates, the circulation of exhaust gas can be suddenly stopped.
2 represents an engine, 2 represents an intake pipe equipped with a carburetor 3, and 4 represents an exhaust pipe. A diaphragm type recirculation control valve 6 is provided in a recirculation passage 5 that connects the exhaust pipe 4 and the intake pipe 2. The valve body 7 of the control valve 6 is biased in a normally closed direction by a spring 9 in a diaphragm chamber 8, and is configured to open against the spring 9 when negative pressure is applied to the diaphragm chamber 8. .

The carburetor 3 has a first sensing port 11 located upstream (from the closed position of the throttle valve 10).
A second sensing port 12 is provided at an upstream location (further than the sensing port 11), and both sensing ports 11 and 12 are connected to the diaphragm chamber 8 of the control valve 6 via negative pressure take-off passages 13 and 14, respectively. When connecting, the negative pressure outlet passage 1 at the first sensing port 11
3 includes an orifice 15 and a first sensing port 11.
A check valve 16 that opens only in the direction from the diaphragm chamber 8 is provided in parallel, while the second sensing port 1
A check valve 17 that opens only in the direction from the diaphragm chamber 8 to the sensing port 12 is provided in the negative pressure take-off passage 14 in FIG.

In this configuration, during idling operation with the throttle valve 10 of the carburetor 3 in the closed position, both sensing ports 11 and 12 are located upstream of the throttle valve 10 and are at atmospheric pressure, so the control Valve 6 does not open and exhaust gas does not flow back into the intake system, but when throttle valve 10 opens, both sensing ports 11 and 12
Alternatively, the negative pressure at either sensing port becomes high and this negative pressure is transmitted to the diaphragm chamber 8 of the control valve 6, so the valve body 7 of the control valve 6 opens against the spring 9, and the air is supplied to the intake system. When the throttle valve 10 is fully open, the negative pressures at both sensing ports 11 and 12 approach atmospheric pressure, so the control valve 6 is closed and the exhaust gas is circulated back to the intake system. Stop.

When the throttle valve 10 is closed between the two sensing ports 11 and 12 during deceleration by suddenly closing the throttle valve 10 from the fully open state, the negative pressure at the second sensing port 12 is atmospheric pressure. On the other hand, the negative pressure in the first sensing port 11 becomes higher, but this negative pressure in the first sensing port 11 is transmitted to the control valve 6 with a delay due to the orifice 15 in the negative pressure extraction passage 13, so that the pressure of the throttle valve 10 increases. The control valve 6 does not open temporarily during the closing movement, and the throttle valve 10 closes to the idling position.

When the throttle 10 is closed to the idling position, the negative pressure in both sensing boats 11 and 12 becomes atmospheric pressure, and this atmospheric pressure flows through the check valve 16 of the negative pressure outlet passage 13 in the first sensing port 11 to the diamond By instantaneously transmitting the signal to the plum chamber 8, the control valve 6 does not open when the throttle valve 10 closes or decelerates, thereby cutting off the recirculation of exhaust gas to the intake system when the engine is decelerating.

Furthermore, when the load increases, such as when the throttle valve 10 is suddenly opened widely from the idling position or the partial position and the load increases, the negative pressure at both sensing ports 11 and 12 becomes high, and this negative pressure is transferred to the second sensing port. Since the negative pressure is instantly transmitted to the diaphragm chamber 8 of the control valve 6 via the check valve 17 in the negative pressure take-out passage 14 at 12, the control valve 6 opens almost simultaneously with the opening of the throttle valve 10 without any delay and flows to the intake system. This is to recirculate the exhaust gas.

Further, during acceleration with the throttle valve 10 slightly opened from the idling position or its vicinity to between the two sensing ports 11.12, that is, during low load rotation, the pressure at the second sensing port 12 is atmospheric pressure, and the pressure at the first sensing port 12 is atmospheric pressure. Negative pressure is generated only at 11 locations, and this negative pressure is at orifice 1.
5 and is transmitted to the diaphragm chamber 8 of the control valve 6, the control valve 6 starts to open slowly due to the delay caused by the orifice 15 and does not open instantaneously.

Next, the throttle valve 10 is connected to the second sensing port 12
When the second sensing port 12 is opened to a certain extent, negative pressure is also generated in the second sensing port 12, and this negative pressure is transmitted to the diaphragm chamber 8 of the control valve 6 without delay. From this point on, the control valve 6
is rapidly opened wide.

In other words, the recirculation of exhaust gas to the intake system gradually increases with a time delay until the engine load reaches a certain level, and increases rapidly without any delay when the engine load exceeds a certain level.

In addition, in the above embodiment, the recirculation control valve 6 was opened and closed directly by the negative pressure of both sensing ports 11 and 12.
The present invention is not limited to this, but as shown in FIG. Needless to say, the present invention can also be applied to an exhaust gas recirculation device provided with an exhaust pressure control valve 19 that is opened.

As described above, according to the present invention, it is possible to improve the responsiveness of exhaust gas recirculation when the engine load increases, so it is possible to effectively reduce NOx by exhaust gas recirculation when the engine load increases. When there is a small load increase, the exhaust gas circulation is delayed and gradually carried out.
It is possible to prevent a decrease in engine output due to the recirculation of exhaust gas in this operating range, and since the recirculation of exhaust gas is immediately cut off when the engine is decelerating, the recirculation of exhaust gas during deceleration can worsen combustion and cause the engine to This has the effect of preventing the operation of the vehicle from stopping.

[Brief explanation of the drawing]

FIG. 1 is a diagram of an apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram of an apparatus according to an embodiment of the present invention. 1...engine, 2...intake pipe, 3...
... Carburetor, 4... Exhaust pipe, 5...
Circulation passage, 6... Circulation control valve, 10...
・Throttle valve, 11, 12...Sensing boat, 13.14...Negative pressure extraction passage, 16.1
7... Check valve, 15... Orifice.

Claims (1)

[Scope of utility model registration request] A recirculation control valve is provided in a recirculation passage that recirculates a portion of the exhaust gas to the intake system, and is normally biased by a spring to open against the spring when negative pressure is applied to the diaphragm chamber. , the diaphragm chamber of the reflux control valve is connected to a first sensing port provided upstream of the closed position of the throttle valve in the carburetor, and a second sensing port provided further upstream of the first sensing port, respectively, and a negative pressure is applied to the diaphragm chamber of the reflux control valve. An orifice and a check valve configured to open only in the direction from the first sensing port to the diaphragm chamber are provided in parallel in the negative pressure extraction passage in the first sensing port, which communicates through the extraction passage; An exhaust gas recirculation control device for an internal combustion engine, wherein a check valve that opens only in the direction from the diaphragm chamber to the second sensing port is provided in the negative pressure extraction passage in the second sensing port.