JPS5918129Y2 - 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.

It is well known that by circulating a portion of exhaust gas back into the intake system, the maximum combustion temperature can be lowered and the generation of nitrogen oxides can be suppressed.

However, when exhaust gas recirculation (hereinafter referred to as EGR) is performed,
This is accompanied by the inconvenience of reduced output and increased fuel consumption.

By the way, when the temperature of the engine cooling water or exhaust gas is lower than a predetermined value, and when the negative pressure due to the opening of the throttle valve near the upstream of the throttle valve during idling is low,
Since the amount of nitrogen oxides generated is small, there is no need to perform EGR.

Therefore, it is desirable to detect the operating state of the engine and perform control to perform EGR only when necessary.

As such an EGR control method, for example, the
Prior art techniques using negative pressure based on the opening of a throttle valve are known, as described in Japanese Patent Publication No. 49525 and Japanese Patent Publication No. 47-34422.

However, in these prior art, the engine
When the operating state changes from the operating state in which R is performed to the state in which it is no longer performed, EGR is immediately stopped, which has the disadvantage that NOx cannot be sufficiently suppressed.

On the other hand, there is an exhaust gas purification method in which unburned components such as HC and CO in the exhaust gas are treated by oxidation reaction by means of, for example, providing a thermal reactor in the exhaust system.

In this type of device, when an abnormally large amount of unburned components are generated in the exhaust gas, they are combusted in the exhaust system.
A so-called afterburn phenomenon occurs.

Particularly when there is a sudden deceleration, the negative pressure inside the intake pipe becomes high, and the fuel remaining in various places inside the intake pipe evaporates at once, and this is sucked into the combustion chamber, making the air-fuel mixture rich and causing unburned components. There is a problem in that the amount of heat increases and afterburn occurs.

The prior art described in Japanese Utility Model Application Publication No. 50-134524 is known to solve this problem, but according to this, the above-mentioned drawbacks and the negative pressure actuator of the EGR valve have a throttle valve during idling. The negative pressure passages provided with electromagnetic valves for applying the negative pressure due to the opening degree of the valve near the upstream of the valve and the suction pipe negative pressure during sudden deceleration are communicated, and the passages of the suction pipe negative pressure are connected to each other. The disadvantage was that the structure was complicated, as it required a negative pressure control device.

The present invention integrates the above prior art, and furthermore,
The object of the present invention is to provide an exhaust gas recirculation control device that eliminates the above-mentioned drawbacks of these devices.

In order to achieve this objective, the present invention has valve ports in the negative pressure actuator that selectively guide the negative pressure near the upstream of the throttle valve during idling and the suction pipe negative pressure above a predetermined value during sudden deceleration. A solenoid switching valve is connected to the valve so that when negative pressure is generated in the suction pipe, the valve port on the suction pipe negative pressure side opens, and the valve port on the negative pressure side of the throttle valve of the switching valve is connected to the valve port on the upstream side of the throttle valve. It is characterized in that it is connected to the atmosphere opening port through a negative pressure electromagnetic control valve, and the control valve is controlled by a vehicle speed switch, a cooling water temperature switch, etc.

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

1 is a horizontally opposed four-cylinder engine, 2 is an intake pipe, 3 is an exhaust pipe, 4 is a thermal reactor installed in the exhaust pipe and oxidizes unburned components in the exhaust gas, and 5 is a communication between the exhaust pipe and the intake pipe. This is an EGR pipe that recirculates exhaust gas.

An EGR for controlling EGR is installed in the middle of this EGR pipe 5.
A valve 6 is provided, and the EGR valve 6 is actuated by a negative pressure actuator 7.

The actuator 7 includes a diaphragm 8 connected to the valve body 6a, a negative pressure chamber 9 partitioned by the diaphragm 8, and a spring 10 that pushes the diaphragm 8 to close the valve. is solenoid switching valve 1
It communicates with the valve chamber of No. 1.

The electromagnetic switching valve 11 has valve ports 12 and 13, and has a valve body 1.
4.15 moves due to the excitation of the excitation coil 16 and opens the valve port 1.
2 and 13 can be selectively opened and closed.

One valve port 12 is connected to a negative pressure outlet 19 a opened near the upstream side of the throttle valve 18 at the idle opening position with respect to the mixture passage of the carburetor through a pipe 17 . 13 is communicated with the suction pipe 2 by a pipe 19 at a position downstream of the throttle valve.

Further, a negative pressure switch 21 having a negative pressure chamber 20 communicating with the suction pipe 2 is provided, and when the negative pressure in the suction pipe exceeds a predetermined value due to sudden deceleration, the negative pressure switch 21 switches the diaphragm 22 is deflected against the spring 23, and the switch 21 is closed.

By closing this switch 21, the excitation coil 16 is connected to the power supply 36 via the main switch 35, and the coil 1
6 is energized, the valve body 14.15 moves to the left, and the valve port 12
is closed and the valve port 13 is opened.

The valve port 12 is further connected to the throttle 3 of a throttle device 26 by a pipe 24.
3, a negative pressure control solenoid valve 25, and a passage having a throttle 34 of the device 26 leading thereto, to an atmosphere opening 27 opened upstream of the carburetor mixture passage.

The relay normally closed contact 29 connects the excitation coil 28 of the negative pressure control solenoid valve 25 to a predetermined vehicle speed, for example, 45 km.
/ h or more, a vehicle speed switch 30 that closes is connected in parallel.

Further, a water temperature switch 32 is connected to the circuit of the relay coil 31, which is closed when the engine cooling water temperature reaches a predetermined temperature, for example, 70° C. or higher.

Next, the operation of this device will be explained.

First, when the engine is idling, the throttle valve 18 is closed and the negative pressure outlet 19a is at atmospheric pressure.

Therefore, the negative pressure chamber 9 of the actuator 7 of the EGR valve 6 is also at atmospheric pressure, and the valve body 6a is pressed against the valve seat and closed, and EGR is not performed.

When the throttle valve is opened and the engine speed is increased, the negative pressure outlet 19a becomes a negative pressure on the downstream side of the throttle valve 18.

At this time, regardless of the vehicle speed, if the engine cooling water temperature is low, the water temperature switch 32 is open and the relay contact 29
is closed, the excitation coil 28 of the solenoid valve 25 is energized, and the valve port 3 is energized.
7 is open.

Therefore, the near leak circuit of the pipe 24 passes through both the fringes 33 and 34, and the amount of near leak is large, so that the negative pressure from the negative pressure outlet 19a to the negative pressure chamber 9 is reduced.

The action of the low negative pressure causes the diaphragm 8 to be pulled up and the valve 6 to be slightly separated from the valve seat, opening the valve opening and either a small amount of EGR is performed or no EGR is performed at all.

When the throttle valve is close to fully open, the negative pressure outlet 19
Part a becomes close to atmospheric pressure, valve 6 is completely closed and EGR is started.
stops.

Next, when the vehicle speed is below a predetermined speed and the engine cooling water temperature reaches a predetermined temperature or higher, the water temperature switch 32 closes.
The relay coil 31 is energized and the two contacts open.

As a result, the excitation coil 28 is demagnetized and the valve port 37 is closed.

Therefore, the near leak circuit by the pipe 24 is limited to the crest 33, the amount of near leak decreases, and the negative pressure in the negative pressure chamber 9 increases.

Therefore, the amount of EGR corresponding to the operating state becomes larger than when the water temperature is low.

When the vehicle speed reaches a predetermined speed or higher, the switch 30 is closed, the excitation coil 28 is energized, and the valve port 37 is opened. Therefore, as described above, the negative pressure becomes low and EGR decreases.

Next, when there is a sudden deceleration, the negative pressure inside the suction pipe 2 increases, and when it reaches a predetermined value or higher, the switch 21 closes rapidly and the switching valve 1
The first excitation coil 16 is excited, the valve bodies 14 and 15 move to the left, the valve port 12 closes, and the valve port 13 opens.

Therefore, the high negative pressure within the suction pipe 2 acts on the negative pressure chamber 9 through the pipe 19 and the valve port 13.

At this time, the negative pressure from the negative pressure outlet 19a is cut off, so the EGR valve 6 opens wide due to the negative pressure in the suction pipe 2, and a large amount of EGR is performed, regardless of the engine water temperature or vehicle speed. .

Then, the air-fuel mixture is diluted by the recirculated exhaust gas,
Afterburn is prevented.

When the deceleration ceases, the switch 21 opens and the original state is restored.

Based on the above, according to the present invention, the negative pressure acting on the EGR valve depending on the opening degree of the throttle valve can be controlled depending on the load, vehicle speed,
The amount of EGR is controlled to correspond to the temperature of the cooling water, and the amount of EGR is adjusted so as not to impair fuel efficiency, output, and drivability (NOx
This can suppress the occurrence of
When the condition is such that the EGR valve is not operated, the negative pressure acting on the EGR valve decreases with a delay from the time mentioned above due to the presence of the above-mentioned throttle, so EGR continues for a certain period of time, which causes the exhaust gas to The generation of NOx can be sufficiently suppressed.

Furthermore, during sudden deceleration, the EGR control of the negative pressure by the throttle valve opening is disabled, the EGR valve is rapidly opened by the negative pressure in the suction pipe, and a larger amount of EGR is quickly performed to dilute the air-fuel mixture. It is possible to cope with and prevent afterburn that occurs during sudden deceleration, and this is done by using an EGR device that uses negative pressure associated with the opening of the throttle valve. , the valve port of a single electromagnetic switching valve is switched and commonly used, which has the effect of simplifying the structure.

Furthermore, by performing EGR during deceleration, the effectiveness of engine braking is improved, which is a very favorable effect from the standpoint of safety.

[Brief explanation of the drawing]

The figure is a system diagram showing an embodiment of the present invention.

Claims (1)

[Scope of utility model registration request] An exhaust gas recirculation valve provided in a passage that recirculates part of the exhaust gas into the suction pipe, a negative pressure actuator that operates the valve, and an exhaust gas recirculation valve that communicates with the negative pressure actuator and that is connected to the suction pipe and the idle opening position. an electromagnetic switching valve having a valve port that can communicate with the mixture passage in the vicinity of the upstream of the throttle valve; a valve port of the electromagnetic switching valve that connects to the mixture passage side, and an opening to the atmosphere upstream of the mixture passage; When the negative pressure in the suction pipe exceeds a predetermined value due to sudden deceleration, the electromagnetic switching valve operates to control the above-mentioned mixture. It is connected to a negative pressure switch that closes the valve port to the passage side, and the negative pressure solenoid control valve is opened when the vehicle speed switch closes when the vehicle speed exceeds a predetermined value, and the water temperature switch that closes when the cooling water temperature exceeds a predetermined value is open. An exhaust gas recirculation control device for an internal combustion engine, characterized in that it is opened by closing a vehicle speed switch and closed by closing a water temperature switch.