JPS6235876Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is aimed at reducing No. ₄ in the exhaust gas of internal combustion engines.
The present invention relates to an exhaust gas recirculation device that recirculates a portion of exhaust gas to the intake system for the purpose of reducing the amount of exhaust gas, and to a device that controls the amount of exhaust gas recirculated to the intake system in accordance with the operating state of the engine.

In order to reduce Nox in the exhaust gas of an internal combustion engine, it is effective to recirculate a portion of the exhaust gas to the intake system, and this is used in various automotive internal combustion engines. The ratio of recirculated exhaust gas to the amount of intake air, that is, the recirculation rate, must be controlled so that it increases in proportion to the engine load. Negative pressure in the vicinity of the closed position of an exhaust gas recirculation control valve and a carburetor throttle valve provided in a recirculation passage connecting the intake system is adjusted according to the exhaust pressure of the engine to act on the exhaust gas recirculation control valve. In an exhaust gas recirculation system of exhaust pressure control type consisting of an exhaust pressure regulating valve, two or more negative pressure ports are provided near the throttle valve closed position of the carburetor, and the throttle valve is connected to the first negative pressure port. In the low load range of the condition, the negative pressure is only in the first negative pressure port, and in the middle to high load condition, in which the throttle valve is located at the second negative pressure port upstream from the first negative pressure port, only the first negative pressure port is applied. In controlling the exhaust gas recirculation rate to increase according to the engine load by activating the exhaust gas recirculation control valve by the negative pressure of the second negative pressure port, the throttle valve In order to prevent the inconvenience caused by introducing atmospheric air from the second negative pressure port located upstream of the negative pressure port, the inside of the negative pressure passage from the second negative pressure port to the exhaust pressure regulating valve is In addition, it has been proposed to provide an orifice or to provide a check valve in series with the orifice that opens from the second negative pressure port toward the exhaust pressure regulating valve.

However, in this prior art, the orifice provided in the negative pressure passage from the second negative pressure port, as in the former case, must have a considerably small diameter in order to restrict the amount of atmospheric air introduced from the second negative pressure port to a small amount. However, if this orifice is made small in diameter, there will be a time delay in the transmission of negative pressure to the exhaust pressure regulating valve when the throttle valve is connected to the second negative pressure port, so exhaust gas recirculation during medium to high loads will be difficult. In addition, if a check valve is installed in series like the latter, the introduction of atmospheric air from the second negative pressure port will be reversed when the throttle valve is connected to the first negative pressure port. Since it is completely blocked by the stop valve and there is no need to make the orifice small in diameter, it is possible to rapidly increase the exhaust gas recirculation rate with the throttle valve connected to the second negative pressure port. When the negative pressure port is closed, atmospheric air is not introduced from the second negative pressure port at all, and the negative pressure is rapidly transmitted to the exhaust pressure regulating valve, causing the recirculation control valve to open rapidly, reducing the amount of exhaust gas recirculation. increases rapidly from the start of reflux, and as a result,
Combustion becomes unstable, drivability worsens, and misfires occur.In short,
In the prior art, it is not possible to control the recirculation of exhaust gas to the intake system so that the recirculation is gradual when the recirculation is opened, and increases sharply in the medium to high load range.

The present invention aims to solve this problem.

For this reason, the present invention provides a pressure-operated exhaust gas recirculation control valve that is normally held closed by a spring in the recirculation passage connecting the intake system and the exhaust system, and that opens when negative pressure is applied to the pressure chamber. and an exhaust pressure regulating valve configured to close a communication pipe to the atmosphere connected to the pressure chamber of the exhaust gas recirculation control valve when the exhaust pressure of the engine increases, and a throttle valve of the carburetor is connected to the communication pipe. An exhaust gas recirculation device comprising a negative pressure passage from a first negative pressure port provided slightly upstream of the closed position of the exhaust gas recirculation device and a negative pressure passage from a second negative pressure port provided further upstream thereof, A check valve and an orifice that open only in the direction toward the second negative pressure port are provided in parallel in the negative pressure passage connecting the second negative pressure port and the communication pipe. .

With this configuration, in a low load range where the throttle valve is applied only to the first negative pressure port, the amount of air regulated by the orifice is introduced from the second negative pressure port into the communication pipe by closing the check valve. Therefore, the opening operation of the exhaust gas recirculation control valve can be performed slowly, while in the medium to high load range where the throttle valve is applied to the second negative pressure port, the negative pressure at the second negative pressure port is When the check valve opens, the exhaust gas recirculation control valve opens quickly and widely because it is quickly transmitted to the communication pipe.

As a result, it is possible to gently control the rapid increase in the amount of recirculation at the start of recirculation of exhaust gas in a low load range, and it is also possible to control a rapid increase in the recirculation rate in a medium to high load range.

An embodiment of the present invention will be described below with reference to the drawings. In the drawings, 1 is an engine, 2 is an intake manifold equipped with a carburetor 4 with an air cleaner 3, 5 is an exhaust pipe,
Reference numeral 6 indicates a diaphragm type exhaust recirculation control valve, and reference numeral 7 indicates an exhaust pressure adjustment valve.
In addition, the outlets are respectively connected to the intake manifold 2 via the reflux passages 10, and the valve body 11 of the reflux control valve 6 is connected to the spring 1 in the diaphragm chamber 12.
3, it is always biased in the closing direction.

The exhaust pressure regulating valve 7 includes a diaphragm 16 that defines an atmosphere communication chamber 14 and an exhaust pressure chamber 15, and communicates the atmosphere communication chamber 14 with an atmosphere communication location such as the air cleaner 3 via an orifice 17.
A communication pipe 19 is provided which is opened and closed by a flap 18 of a diaphragm 16, and a spring 20 keeps the communication pipe 19 open at all times. It is connected to the orifice 8 via a passage 21, and the communication pipe 1
9 is connected to the diaphragm chamber 12 of the recirculation control valve 6 through a passage 22, and is provided in the carburetor 4 at a position slightly upstream of the closed position (idle opening) of the throttle valve 23. Pressure port 2
4 via a negative pressure passage 25, and the communication pipe 19 is connected to the first negative pressure port 24 in the carburetor 4.
Further, it is connected via a negative pressure passage 27 to a second negative pressure port 26 provided at an appropriately upstream site.

There is an orifice 28 in the negative pressure passage 27 leading from the second negative pressure port 26 to the communication pipe 19 of the exhaust pressure regulating valve 7, and an orifice 28 from the exhaust pressure regulating valve 7 to the second negative pressure port 2.
A check valve 29 that opens only in the direction toward 6 is provided in parallel.

In this configuration, when the throttle valve 23 is fully closed and the engine is idling, both negative pressure ports 2
4 and 26 are both located upstream of the throttle valve 23 and are at atmospheric pressure, so negative pressure does not act on the reflux control valve 6, so the reflux control valve 6 does not open and operate, and the intake system Exhaust gas shall not be returned to the Next, the throttle valve 23 is connected to the first negative pressure port 24.
In a low load range where the valve is opened to a certain point, the negative pressure at the first negative pressure port 24 becomes large, and this negative pressure is transmitted to the atmosphere communication chamber 14 of the exhaust pressure regulating valve 7, and the atmosphere communication chamber 14 becomes While the negative pressure is between the negative pressure and the atmospheric pressure due to the orifice 17, the exhaust pressure rises as the exhaust gas from the engine increases, and this exhaust pressure causes the diaphragm 16 to close the communication pipe 19 and close the first Negative pressure port 2
4 acts on the diaphragm chamber 12 of the reflux control valve 6 through the passage 22, so that the reflux control valve 6
The valve body 11 is opened by the negative pressure of the first negative pressure port 24, and the recirculation of exhaust gas to the intake system is started. In a medium to high load range when the throttle valve 23 is opened to a point close to the second negative pressure port 26, the negative pressure at the second negative pressure port 26 also increases, and therefore the diaphragm chamber 12 of the reflux control valve 6 is the first negative pressure port 2
4 and the second negative pressure port 26 act to open the valve body 11 more, the rate of exhaust gas recirculation to the intake system increases.
When the throttle valve 23 is fully open, the negative pressure at both load ports 24 and 26 approaches atmospheric pressure, so the recirculation control valve 6 is closed and the recirculation of exhaust gas to the intake system is cut off.

Then, as mentioned above, the throttle valve 23
In a low load range where the second negative pressure port 26 is located upstream of the throttle valve 23 compared to the negative pressure port 24, the communication pipe 19 of the exhaust pressure regulating valve 7 is connected to the second negative pressure port 26. Atmospheric air regulated by the orifice 28 in the pressure passage 27 is introduced, and the negative pressure acting on the reflux control valve 6 is thereby reduced to the first
The negative pressure is adjusted to a value between the negative pressure of the negative pressure port 24 and atmospheric pressure, and the negative pressure acting on the reflux control valve 12 can be reduced by reducing the diameter of the orifice 28 to the first negative pressure port. The diameter of the orifice 28 can be arbitrarily set so that the negative pressure approaches the negative pressure of the exhaust gas 24, and the atmospheric pressure approaches the atmospheric pressure by increasing the diameter of the orifice 28. This allows the gas recirculation amount to rise slowly, while the throttle valve 23 is connected to the second negative pressure port 2.
6, the check valve 29 in parallel with the orifice 28 opens and the negative pressure in the second negative pressure port 26 is transmitted to the reflux control valve 6 without any time delay. The exhaust gas recirculation rate can be increased quickly according to the load without any time delay, regardless of the fact that the orifice 28 is set so that the recirculation amount increases gradually at the start of recirculation.

That is, in the prior art, if the orifice in the negative pressure passage from the second negative pressure port is made small in diameter, there will be a delay in increasing the reflux rate in the medium to high load range. If a check valve is installed in series in the negative pressure passage from the port, the amount of reflux will increase when reflux starts in the low load range, but
By configuring the orifice 28 and the check valve 29 in parallel in the negative pressure passage 27 from the second negative pressure port 26 as described above, it is possible to gently control the rapid increase in the recirculation amount at the start of recirculation in a low load region. On the other hand, rapid increase control of the reflux rate at medium to high loads can be accurately performed.

Therefore, according to the present invention, it is possible to recirculate exhaust gas to the intake system without causing deterioration of drivability or misfire in a low load range, and without causing insufficient recirculation of exhaust gas in a medium to high load range. It has an effect that can be controlled easily.

[Brief explanation of the drawing]

The drawing is a diagram of an apparatus according to an embodiment of the present invention. 1...engine, 2...intake manifold, 4...
Carburetor, 23...throttle valve, 5...exhaust pipe,
9, 10...Recirculation passage, 6...Exhaust gas recirculation control valve, 7...Exhaust pressure adjustment valve, 19...Communication pipe, 24...
...First negative pressure port, 26...Second negative pressure port, 2
5... Negative pressure passage, 27... Negative pressure passage, 28... Orifice, 29... Check valve.

Claims (1)

[Scope of utility model registration request] A pressure-operated exhaust gas recirculation control valve is provided in a recirculation passage connecting the intake system and the exhaust system, and the valve is normally held closed by a spring and is opened when negative pressure is applied to the pressure chamber. The gas recirculation control valve is equipped with an exhaust pressure regulating valve that closes a communication pipe to the atmosphere connected to the pressure chamber when the exhaust pressure of the engine increases, and the communication pipe is provided with a valve that is connected to the atmosphere at a position that is slightly lower than the closed position of the throttle valve of the carburetor. In an exhaust gas recirculation device comprising a negative pressure passage from a first negative pressure port provided upstream and a negative pressure passage from a second negative pressure port provided further upstream, the second negative pressure port Exhaust gas recirculation control for an internal combustion engine, characterized in that a check valve that opens only in the direction toward the second negative pressure port and an orifice are provided in parallel in the negative pressure passage connecting the communication pipe and the second negative pressure port. Device.