JPS6041224B2 - Internal combustion engine exhaust gas recirculation control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an exhaust gas recirculation control device for an internal combustion engine.

By circulating a portion of the exhaust gas back into the intake system, combustion can be slowed down, the maximum combustion temperature can be kept low, and the generation of nitrogen oxides can be suppressed.

However, such exhaust gas recirculation (referred to as EGR) reduces combustion efficiency, resulting in disadvantages such as a reduction in output, deterioration in fuel efficiency, and deterioration in drivability. On the other hand, nitrogen oxides are not generated in large amounts throughout the entire operating range, but are generated in large amounts during acceleration. Therefore, in order to increase the amount of EGR during acceleration,
An R reflux control device is provided. However, when the transmission speed reaches high speed during the low gear stage, the exhaust gas temperature becomes abnormally high, and if ECR is performed at that time, a large amount of unburned components due to incomplete combustion will flow into the exhaust system, and the exhaust gas temperature will become abnormally high. The increase in gas temperature causes combustion within an exhaust purification device such as a thermal reactor provided in the exhaust system. Combustion of such a large amount of unburned components may cause the exhaust purification device to overheat, creating a risk of fire or the like. In addition, the related prior art, Tokukan Sho 49-30712, stops exhaust gas recirculation during high speed rotation, so when exhaust gas recirculation is stopped, there is a problem with engine operability due to combustion discontinuity. In Hakama Sekisho 52-30523, the lift amount of the valve body provided in the EGR valve is suppressed during high-speed operation, and the recirculation amount is reduced without completely stopping exhaust gas recirculation. When this happens, the switch is turned on and the IJ lift amount control device of the valve body suddenly operates, so at this point the exhaust gas recirculation range changes suddenly, which again causes the problem of unstable combustion.

Furthermore, in Hakama Kosho 47-I 051, two valve bodies are provided for the EGR valve to suppress the amount of exhaust gas recirculated according to the operating conditions, but it is difficult to set the valve shape, and carbon deposits It cannot be expected to control the actual exhaust gas recirculation amount by such methods. The present invention was made in order to solve such problems.
By controlling the amount of EGR in the exhaust system, we suppress the generation of nitrogen oxides without reducing output, deteriorating fuel efficiency, or drivability. We also limit the amount of EGR, especially during high speed rotation in low gears of the transmission. E that can prevent overheating of exhaust purification equipment
The present invention provides a GR control device. This will be explained below with reference to the drawings.

In the figure, 1 is the engine, 2 is the suction boat, and 3 is the engine.
is an exhaust boat, 4 is an exhaust pipe, 5 is an exhaust purification device such as a thermal reactor, and the exhaust boat 3 is equipped with an EGR pipe 6.
The pipe passes through the EGR valve 7 and connects to the suction passage 8.
is connected to. The ECR valve 7 is composed of a diaphragm 11 that operates a separate body 10, a spring 12 that displaces the diaphragm and closes the valve, and a negative pressure chamber 13 partitioned by the diaphragm 11, and the negative pressure chamber is connected to a negative pressure passage ( Sekiguchi 19 located immediately upstream of the idle position of the throttle valve 17 via the electromagnetic cut-off valve tatami 5 via the pipe) 14
In this case, the suction passage 8 is fitted. Electromagnetic cut-off valve 15
When the electromagnetic coil 21 is energized, the boat 33 enters the atmosphere 16.
The pipe 14 is configured so that it can be opened, and the pipe 14 is configured so that two rivers of air can pass through the pipe 14 through a leak hole 29 by means of a solenoid valve 18.

The electromagnetic coil 21 of the electromagnetic switching valve 15 has a choke switch 22 that closes when the choke is pulled, a water temperature switch 23, an ignition switch 24, and a choke pilot lamp 25.
A resistor 27 is connected in parallel to the water temperature switch 23. The water temperature switch 23 indicates that the engine cooling water temperature is, for example, 35qo.
It is configured so that it closes when the temperature exceeds that limit. On the other hand, the electromagnetic coil 28 of the electromagnetic valve 18 is connected to the battery 26 by a circuit including a remote switch 30, a mission switch 31, and a vehicle speed switch 32 in parallel with both switches. The distance switch 30 closes when the distance reaches a predetermined distance, for example, 35 m/h or more, and the distance switch 32 closes when the speed exceeds, for example, 45 m/h. Further, the mission switch 31 is configured to close when the first gear and the second gear are set. Next, the operation of this device will be explained.

When the choke is pulled during startup, the choke switch 22 closes. When the water temperature is low, the water temperature switch 23 is open, so the choke pilot lamp 25 is connected to the power supply via the resistor 27. Therefore, the choke pilot lamp 25 lights up faintly, and on the other hand, the coil 21 is energized, the boat 33 of the cut-off valve 15 to the atmosphere 16 is opened, the negative pressure chamber 13 is transported to the atmosphere 16, and the negative pressure chamber 13 and the suction passage 8 are cut off. At this time, when the vehicle speed is 35 mm/h or less in the low gear, and if the vehicle speed is 45 mm/h or less even in the high gear, the electromagnetic coil 28 is de-energized, so the cargo pressure passage 14 is cut off from the atmosphere. However, since the switching valve 15 blocks the negative pressure passage 14, the suction negative pressure does not act on the negative pressure chamber 13, and EGR is not performed until the EGR valve 7 is closed. As the warm-up progresses and the water temperature rises, the switch 23 closes, current flows bypassing the resistor 27, and the choke pilot lamp 25 becomes bright, prompting the driver to complete the lowering. inform.

When the driver returns the choke, the choke switch 22 opens, the magnetic coil 21 becomes vertically magnetic, the switching valve 15 closes the boat to the atmosphere, and the intake passage 14 side is closed. At this time, car selection is
When the vehicle speed is less than 35 m/h in the low speed gear, and if the vehicle speed is less than 45 m/h even in the far gear, the electromagnetic coil 28 is de-energized and the negative pressure passage 14 is blocked from the atmosphere. ing. Therefore,
When the throttle valve 17 is opened and the opening 19 is on the downstream side of the throttle valve 17, negative pressure acts on the negative pressure chamber 13 through the pipe 14. This displaces the diaphragm 11, opens the valve, performs EGR, and controls combustion. When the transmission is in the first or second gear, when the speed exceeds 39 m/h, the mission switch 31 and the remote switch 30 close, the electromagnetic coil 28 is energized, and the electromagnetic valve 18 is activated via the leak hole 29. The atmosphere passes through 20'. Therefore, the negative pressure acting on the negative pressure chamber 13 is slowly controlled by the throttling effect of the leak hole 29. The EGR amount gradually decreases. In this way, even in low gears, the engine rotates at high speeds at a relatively low distance, so under such conditions, the amount of EGR is reduced, so combustion is completed, and less unburned components are discharged into the exhaust system. At the same time, the exhaust gas temperature rise can also be suppressed, so overheating of the exhaust gas purification device in the exhaust system is prevented. Furthermore, since the ECR amount does not change suddenly, engine drivability does not deteriorate due to unstable combustion. The mission switch 31 is open when the transmission is in anything other than the first far or second gear, but even in such a case, when the vehicle speed exceeds 45 mm/h, the vehicle speed switch 32 closes.
The electromagnetic coil 28 is energized to leak the EGR valve operating pressure to the atmosphere and gradually control the negative pressure to gradually reduce the EGR amount without reducing it suddenly, resulting in fuel efficiency L output,
Prevents deterioration of drivability. As is clear from the above, according to the present invention, it is possible not only to control the EGR amount according to the driving condition and prevent deterioration of fuel efficiency and drivability, and decrease in output, but also to prevent the engine from rotating at high speed in low gears. In some cases, it is possible to reduce the amount of EGR and prevent overheating of the exhaust gas purification device in the exhaust system.

[Brief explanation of drawings]

The figure is a schematic diagram showing an embodiment of the present invention. 1...Engine, 2...Suction boat, 3...
...Exhaust boat, 4...Exhaust pipe, 5...
Exhaust purification device, 6...・ECR pipe, 7...
・ECR valve, 8... Suction passage, 10...
Valve body, 11...Diaphragm, 12...
・Spring, 13... Negative pressure chamber, 14...
Negative pressure pipe, 15... Sagi magnetic switching valve, 16...
...Atmosphere" 17...Boat, i8...Solenoid valve, 19...Closed, 20...Atmosphere, 21.
...Electromagnetic coil, 22...Choke switch, 2
3...Water temperature switch, 24...Ignition switch, 25...Choke pilot lamp, 26...
・Battery, 27. …．・Resistance, 28... Electromagnetic coil,
29...Leak hole, 30...Car far switch, 32...Car far switch, 31...Mission switch, 33...Boat.

Claims (1)

[Claims] 1. In an exhaust gas recirculation control device in which an EGR valve having a negative pressure chamber that responds to the negative pressure of the intake system is installed in a passage that recirculates part of the exhaust gas to the intake system, the negative pressure chamber is connected to the A negative pressure passage communicates with an opening that opens immediately upstream of the throttle valve at the idle position via an electromagnetic switching valve that is operated by opening and closing, and the vehicle speed and A solenoid valve is provided that opens and closes with a switch that is activated depending on the vehicle speed and transmission gear.
A first switch that closes at a predetermined vehicle speed or higher and a second switch that closes at a second predetermined vehicle speed or higher in a low gear of the transmission.
switches are configured in parallel, and a leak hole is provided on the atmospheric side of the solenoid valve through which negative pressure in the negative pressure passage for controlling the amount of exhaust gas recirculation leaks to the atmosphere when at least one of the switches is closed. An exhaust gas recirculation control device for an internal combustion engine, characterized in that: